SEC Info  
    Home      Search      My Interests      Help      Sign In      Please Sign In

CASI Pharmaceuticals, Inc. – ‘10-K’ for 12/31/18 – ‘EX-101.DEF’

On:  Friday, 3/29/19, at 10:22am ET   ·   For:  12/31/18   ·   Accession #:  1144204-19-16832   ·   File #:  0-20713

Previous ‘10-K’:  ‘10-K’ on 3/29/18 for 12/31/17   ·   Next:  ‘10-K’ on 3/16/20 for 12/31/19   ·   Latest:  ‘10-K’ on 3/28/22 for 12/31/21   ·   5 References:   

Find Words in Filings emoji
 
  in    Show  and   Hints

  As Of               Filer                 Filing    For·On·As Docs:Size             Issuer                      Filing Agent

 3/29/19  CASI Pharmaceuticals, Inc.        10-K       12/31/18   91:7.7M                                   Toppan Merrill/FA

Annual Report   —   Form 10-K   —   Sect. 13 / 15(d) – SEA’34
Filing Table of Contents

Document/Exhibit                   Description                      Pages   Size 

 1: 10-K        Annual Report                                       HTML    592K 
 2: EX-10.20    Material Contract                                   HTML     25K 
 3: EX-10.21    Material Contract                                   HTML     31K 
 4: EX-10.22    Material Contract                                   HTML     34K 
 5: EX-10.23    Material Contract                                   HTML     69K 
 6: EX-10.24    Material Contract                                   HTML     50K 
 7: EX-10.25    Material Contract                                   HTML    152K 
 8: EX-10.26    Material Contract                                   HTML     90K 
 9: EX-21       Subsidiaries List                                   HTML     21K 
10: EX-23.1     Consent of Experts or Counsel                       HTML     25K 
11: EX-23.2     Consent of Experts or Counsel                       HTML     25K 
12: EX-31.1     Certification -- §302 - SOA'02                      HTML     27K 
13: EX-31.2     Certification -- §302 - SOA'02                      HTML     27K 
14: EX-32.1     Certification -- §906 - SOA'02                      HTML     24K 
15: EX-32.2     Certification -- §906 - SOA'02                      HTML     24K 
22: R1          Document and Entity Information                     HTML     59K 
23: R2          Consolidated Balance Sheets                         HTML    105K 
24: R3          Consolidated Balance Sheets [Parenthetical]         HTML     44K 
25: R4          Consolidated Statements of Operations and           HTML     65K 
                Comprehensive Loss                                               
26: R5          Consolidated Statements of Stockholders' Equity     HTML     77K 
27: R6          Consolidated Statements of Cash Flows               HTML    117K 
28: R7          Description of Business                             HTML     60K 
29: R8          Summary of Significant Accounting Policies          HTML     75K 
30: R9          Acquisition of Abbreviated New Drug Applications    HTML     40K 
                From Sandoz                                                      
31: R10         Acquisition of Abbreviated New Drug Application     HTML     29K 
                From Laurus Labs                                                 
32: R11         Investment in Equity Securities                     HTML     54K 
33: R12         Property and Equipment                              HTML     61K 
34: R13         Intangible Assets                                   HTML     63K 
35: R14         Establishment of Casi Wuxi                          HTML     27K 
36: R15         Note Payable                                        HTML     28K 
37: R16         Stockholders' Equity                                HTML     90K 
38: R17         Employee Retirement Plan                            HTML     28K 
39: R18         Stock-Based Compensation                            HTML    310K 
40: R19         Income Taxes                                        HTML    173K 
41: R20         Fair Value Measurements                             HTML    132K 
42: R21         Related Party Transactions                          HTML     32K 
43: R22         License Arrangements                                HTML     33K 
44: R23         Commitments and Contingencies                       HTML     52K 
45: R24         Subsequent Event                                    HTML     27K 
46: R25         Summary of Significant Accounting Policies          HTML    116K 
                (Policies)                                                       
47: R26         Acquisition of Abbreviated New Drug Applications    HTML     33K 
                From Sandoz (Tables)                                             
48: R27         Investment in Equity Securities (Tables)            HTML     48K 
49: R28         Property and Equipment (Tables)                     HTML     59K 
50: R29         Intangible Assets (Tables)                          HTML     63K 
51: R30         Stockholders' Equity (Tables)                       HTML     76K 
52: R31         Stock-Based Compensation (Tables)                   HTML    304K 
53: R32         Income Taxes (Tables)                               HTML    171K 
54: R33         Fair Value Measurements (Tables)                    HTML    116K 
55: R34         Commitments and Contingencies (Tables)              HTML     41K 
56: R35         Description of Business (Details Textual)           HTML     61K 
57: R36         Summary of Significant Accounting Policies          HTML     41K 
                (Details Textual)                                                
58: R37         Acquisition of Abbreviated New Drug Applications    HTML     27K 
                From Sandoz (Details)                                            
59: R38         Acquisition of Abbreviated New Drug Applications    HTML     34K 
                From Sandoz (Details Textual)                                    
60: R39         Acquisition of Abbreviated New Drug Application     HTML     38K 
                From Laurus Labs (Details Textual)                               
61: R40         Investment in Equity Securities (Details)           HTML     29K 
62: R41         Investment in Equity Securities (Details Textual)   HTML     41K 
63: R42         Property and Equipment (Details)                    HTML     36K 
64: R43         Property and Equipment (Details Textual)            HTML     29K 
65: R44         Intangible Assets (Details)                         HTML     33K 
66: R45         Intangible Assets (Details 1)                       HTML     36K 
67: R46         Intangible Assets (Details Textual)                 HTML     23K 
68: R47         Establishment of Casi Wuxi (Details Textual)        HTML     34K 
69: R48         Note Payable (Details Textual)                      HTML     35K 
70: R49         Stockholders' Equity (Details)                      HTML     46K 
71: R50         Stockholders' Equity (Details Textual)              HTML    133K 
72: R51         Employee Retirement Plan (Details Textual)          HTML     25K 
73: R52         Stock-Based Compensation (Details)                  HTML     31K 
74: R53         Stock-Based Compensation (Details 1)                HTML     35K 
75: R54         Stock-Based Compensation (Details 2)                HTML     70K 
76: R55         Stock-Based Compensation (Details 3)                HTML     61K 
77: R56         Stock-Based Compensation (Details Textual)          HTML     60K 
78: R57         Income Taxes (Details)                              HTML     29K 
79: R58         Income Taxes (Details 1)                            HTML     43K 
80: R59         Income Taxes (Details 2)                            HTML     52K 
81: R60         Income Taxes (Details 3)                            HTML     32K 
82: R61         Income Taxes (Details Textual)                      HTML     45K 
83: R62         Fair Value Measurements (Details)                   HTML     34K 
84: R63         Fair Value Measurements (Details 1)                 HTML     32K 
85: R64         Fair Value Measurements (Details Textual)           HTML     27K 
86: R65         Related Party Transactions (Details Textual)        HTML     50K 
87: R66         Commitments and Contingencies (Details)             HTML     35K 
88: R67         Commitments and Contingencies (Details Textual)     HTML     57K 
90: XML         IDEA XML File -- Filing Summary                      XML    148K 
89: EXCEL       IDEA Workbook of Financial Reports                  XLSX     86K 
16: EX-101.INS  XBRL Instance -- casi-20181231                       XML   2.33M 
18: EX-101.CAL  XBRL Calculations -- casi-20181231_cal               XML    125K 
19: EX-101.DEF  XBRL Definitions -- casi-20181231_def                XML    850K 
20: EX-101.LAB  XBRL Labels -- casi-20181231_lab                     XML    954K 
21: EX-101.PRE  XBRL Presentations -- casi-20181231_pre              XML    971K 
17: EX-101.SCH  XBRL Schema -- casi-20181231                         XSD    180K 
91: ZIP         XBRL Zipped Folder -- 0001144204-19-016832-xbrl      Zip    167K 


‘EX-101.DEF’   —   XBRL Definitions — casi-20181231_def


This Exhibit is an XBRL XML File.


                                                                                                                                                                                
<?xml version="1.0" encoding="windows-1252"?>
<!-- DataTracks Rainbow V 3.0 - www.datatracks.com - on 29-March-2019 [02:08:25] {AM} -->
<linkbase xmlns="http://www.xbrl.org/2003/linkbase" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xlink="http://www.w3.org/1999/xlink" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns:xbrldt="http://xbrl.org/2005/xbrldt">
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#ConsolidatedBalanceSheets" roleURI="http://www.entremed.com/role/ConsolidatedBalanceSheets"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#ConsolidatedBalanceSheetsParenthetical" roleURI="http://www.entremed.com/role/ConsolidatedBalanceSheetsParenthetical"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#ConsolidatedStatementsOfOperationsAndComprehensiveLoss" roleURI="http://www.entremed.com/role/ConsolidatedStatementsOfOperationsAndComprehensiveLoss"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#ConsolidatedStatementsOfStockholdersEquity" roleURI="http://www.entremed.com/role/ConsolidatedStatementsOfStockholdersEquity"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#ConsolidatedStatementsOfCashFlows" roleURI="http://www.entremed.com/role/ConsolidatedStatementsOfCashFlows"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#FairValueMeasurementsTables" roleURI="http://www.entremed.com/role/FairValueMeasurementsTables"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#DescriptionOfBusinessDetailsTextual" roleURI="http://www.entremed.com/role/DescriptionOfBusinessDetailsTextual"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#SummaryOfSignificantAccountingPoliciesDetailsTextual" roleURI="http://www.entremed.com/role/SummaryOfSignificantAccountingPoliciesDetailsTextual"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#AcquisitionOfAbbreviatedNewDrugApplicationsFromSandozDetails" roleURI="http://www.entremed.com/role/AcquisitionOfAbbreviatedNewDrugApplicationsFromSandozDetails"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#AcquisitionOfAbbreviatedNewDrugApplicationsFromSandozDetailsTextual" roleURI="http://www.entremed.com/role/AcquisitionOfAbbreviatedNewDrugApplicationsFromSandozDetailsTextual"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#AcquisitionOfAbbreviatedNewDrugApplicationFromLaurusLabsDetailsTextual" roleURI="http://www.entremed.com/role/AcquisitionOfAbbreviatedNewDrugApplicationFromLaurusLabsDetailsTextual"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#InvestmentInEquitySecuritiesDetails" roleURI="http://www.entremed.com/role/InvestmentInEquitySecuritiesDetails"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#InvestmentInEquitySecuritiesDetailsTextual" roleURI="http://www.entremed.com/role/InvestmentInEquitySecuritiesDetailsTextual"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#PropertyAndEquipmentDetails" roleURI="http://www.entremed.com/role/PropertyAndEquipmentDetails"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#PropertyAndEquipmentDetailsTextual" roleURI="http://www.entremed.com/role/PropertyAndEquipmentDetailsTextual"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#IntangibleAssetsDetails" roleURI="http://www.entremed.com/role/IntangibleAssetsDetails"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#IntangibleAssetsDetails1" roleURI="http://www.entremed.com/role/IntangibleAssetsDetails1"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#IntangibleAssetsDetailsTextual" roleURI="http://www.entremed.com/role/IntangibleAssetsDetailsTextual"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#EstablishmentOfCasiWuxiDetailsTextual" roleURI="http://www.entremed.com/role/EstablishmentOfCasiWuxiDetailsTextual"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#NotePayableDetailsTextual" roleURI="http://www.entremed.com/role/NotePayableDetailsTextual"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#StockholdersEquityDetails" roleURI="http://www.entremed.com/role/StockholdersEquityDetails"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#StockholdersEquityDetailsTextual" roleURI="http://www.entremed.com/role/StockholdersEquityDetailsTextual"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#EmployeeRetirementPlanDetailsTextual" roleURI="http://www.entremed.com/role/EmployeeRetirementPlanDetailsTextual"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#StockBasedCompensationDetails" roleURI="http://www.entremed.com/role/StockBasedCompensationDetails"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#StockBasedCompensationDetails1" roleURI="http://www.entremed.com/role/StockBasedCompensationDetails1"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#StockBasedCompensationDetails2" roleURI="http://www.entremed.com/role/StockBasedCompensationDetails2"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#StockBasedCompensationDetails3" roleURI="http://www.entremed.com/role/StockBasedCompensationDetails3"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#StockBasedCompensationDetailsTextual" roleURI="http://www.entremed.com/role/StockBasedCompensationDetailsTextual"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#IncomeTaxesDetails" roleURI="http://www.entremed.com/role/IncomeTaxesDetails"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#IncomeTaxesDetails1" roleURI="http://www.entremed.com/role/IncomeTaxesDetails1"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#IncomeTaxesDetails2" roleURI="http://www.entremed.com/role/IncomeTaxesDetails2"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#IncomeTaxesDetails3" roleURI="http://www.entremed.com/role/IncomeTaxesDetails3"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#IncomeTaxesDetailsTextual" roleURI="http://www.entremed.com/role/IncomeTaxesDetailsTextual"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#FairValueMeasurementsDetails" roleURI="http://www.entremed.com/role/FairValueMeasurementsDetails"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#FairValueMeasurementsDetails1" roleURI="http://www.entremed.com/role/FairValueMeasurementsDetails1"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#FairValueMeasurementsDetailsTextual" roleURI="http://www.entremed.com/role/FairValueMeasurementsDetailsTextual"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#RelatedPartyTransactionsDetailsTextual" roleURI="http://www.entremed.com/role/RelatedPartyTransactionsDetailsTextual"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#CommitmentsAndContingenciesDetails" roleURI="http://www.entremed.com/role/CommitmentsAndContingenciesDetails"/>
<roleRef xlink:type="simple" xlink:href="casi-20181231.xsd#CommitmentsAndContingenciesDetailsTextual" roleURI="http://www.entremed.com/role/CommitmentsAndContingenciesDetailsTextual"/>
<arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
<arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
<arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
<arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
<arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
<arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/notAll" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#notAll"/>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/ConsolidatedBalanceSheets">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_151"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_149"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_151" xlink:to="loc_us-gaap_StatementTable_149" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_dei_LegalEntityAxis_150"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_149" xlink:to="loc_dei_LegalEntityAxis_150" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_157"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_150" xlink:to="loc_dei_EntityDomain_157" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_157_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_150" xlink:to="loc_dei_EntityDomain_157_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AssetsAbstract" xlink:label="loc_us-gaap_AssetsAbstract_152"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_151" xlink:to="loc_us-gaap_AssetsAbstract_152" use="optional" order="5"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AssetsCurrentAbstract" xlink:label="loc_us-gaap_AssetsCurrentAbstract_153"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_152" xlink:to="loc_us-gaap_AssetsCurrentAbstract_153" use="optional" order="6"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_158"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_153" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_158" use="optional" order="7"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:label="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_159"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_153" xlink:to="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_159" use="optional" order="8"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AssetsCurrent" xlink:label="loc_us-gaap_AssetsCurrent_160"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_153" xlink:to="loc_us-gaap_AssetsCurrent_160" use="optional" order="9"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShortTermInvestments" xlink:label="loc_us-gaap_ShortTermInvestments_365702"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_153" xlink:to="loc_us-gaap_ShortTermInvestments_365702" use="optional" order="10"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_161"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_152" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_161" use="optional" order="11"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherAssetsNoncurrent" xlink:label="loc_us-gaap_OtherAssetsNoncurrent_162"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_152" xlink:to="loc_us-gaap_OtherAssetsNoncurrent_162" use="optional" order="12"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_Assets" xlink:label="loc_us-gaap_Assets_163"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_152" xlink:to="loc_us-gaap_Assets_163" use="optional" order="13"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_365706"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_152" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_365706" use="optional" order="14"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_154"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_151" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_154" use="optional" order="15"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LiabilitiesCurrentAbstract" xlink:label="loc_us-gaap_LiabilitiesCurrentAbstract_155"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_154" xlink:to="loc_us-gaap_LiabilitiesCurrentAbstract_155" use="optional" order="16"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccountsPayableCurrent" xlink:label="loc_us-gaap_AccountsPayableCurrent_164"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_155" xlink:to="loc_us-gaap_AccountsPayableCurrent_164" use="optional" order="17"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccountsPayableRelatedPartiesCurrent" xlink:label="loc_us-gaap_AccountsPayableRelatedPartiesCurrent_165"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_155" xlink:to="loc_us-gaap_AccountsPayableRelatedPartiesCurrent_165" use="optional" order="18"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccruedLiabilitiesCurrent" xlink:label="loc_us-gaap_AccruedLiabilitiesCurrent_166"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_155" xlink:to="loc_us-gaap_AccruedLiabilitiesCurrent_166" use="optional" order="19"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LiabilitiesCurrent" xlink:label="loc_us-gaap_LiabilitiesCurrent_167"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_155" xlink:to="loc_us-gaap_LiabilitiesCurrent_167" use="optional" order="20"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NotesPayableCurrent" xlink:label="loc_us-gaap_NotesPayableCurrent_365761"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_155" xlink:to="loc_us-gaap_NotesPayableCurrent_365761" use="optional" order="21"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongTermNotesPayable" xlink:label="loc_us-gaap_LongTermNotesPayable_168"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_154" xlink:to="loc_us-gaap_LongTermNotesPayable_168" use="optional" order="22"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_Liabilities" xlink:label="loc_us-gaap_Liabilities_170"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_154" xlink:to="loc_us-gaap_Liabilities_170" use="optional" order="23"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommitmentsAndContingencies" xlink:label="loc_us-gaap_CommitmentsAndContingencies_171"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_154" xlink:to="loc_us-gaap_CommitmentsAndContingencies_171" use="optional" order="24"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockholdersEquityAbstract" xlink:label="loc_us-gaap_StockholdersEquityAbstract_156"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_154" xlink:to="loc_us-gaap_StockholdersEquityAbstract_156" use="optional" order="25"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PreferredStockValue" xlink:label="loc_us-gaap_PreferredStockValue_172"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_156" xlink:to="loc_us-gaap_PreferredStockValue_172" use="optional" order="26"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockValue" xlink:label="loc_us-gaap_CommonStockValue_173"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_156" xlink:to="loc_us-gaap_CommonStockValue_173" use="optional" order="27"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdditionalPaidInCapital" xlink:label="loc_us-gaap_AdditionalPaidInCapital_174"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_156" xlink:to="loc_us-gaap_AdditionalPaidInCapital_174" use="optional" order="28"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TreasuryStockValue" xlink:label="loc_us-gaap_TreasuryStockValue_175"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_156" xlink:to="loc_us-gaap_TreasuryStockValue_175" use="optional" order="29"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_176"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_156" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_176" use="optional" order="30"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="loc_us-gaap_StockholdersEquity_177"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_156" xlink:to="loc_us-gaap_StockholdersEquity_177" use="optional" order="31"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_365764"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_156" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_365764" use="optional" order="32"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquity" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_178"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_154" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquity_178" use="optional" order="33"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherLiabilitiesNoncurrent" xlink:label="loc_us-gaap_OtherLiabilitiesNoncurrent_365762"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_154" xlink:to="loc_us-gaap_OtherLiabilitiesNoncurrent_365762" use="optional" order="34"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/ConsolidatedBalanceSheetsParenthetical">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_309"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_307"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_309" xlink:to="loc_us-gaap_StatementTable_307" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_dei_LegalEntityAxis_308"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_307" xlink:to="loc_dei_LegalEntityAxis_308" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_310"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_308" xlink:to="loc_dei_EntityDomain_310" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_310_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_308" xlink:to="loc_dei_EntityDomain_310_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PreferredStockParOrStatedValuePerShare" xlink:label="loc_us-gaap_PreferredStockParOrStatedValuePerShare_311"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_309" xlink:to="loc_us-gaap_PreferredStockParOrStatedValuePerShare_311" use="optional" order="5"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PreferredStockSharesAuthorized" xlink:label="loc_us-gaap_PreferredStockSharesAuthorized_312"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_309" xlink:to="loc_us-gaap_PreferredStockSharesAuthorized_312" use="optional" order="6"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PreferredStockSharesIssued" xlink:label="loc_us-gaap_PreferredStockSharesIssued_313"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_309" xlink:to="loc_us-gaap_PreferredStockSharesIssued_313" use="optional" order="7"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PreferredStockSharesOutstanding" xlink:label="loc_us-gaap_PreferredStockSharesOutstanding_314"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_309" xlink:to="loc_us-gaap_PreferredStockSharesOutstanding_314" use="optional" order="8"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockParOrStatedValuePerShare" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_315"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_309" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_315" use="optional" order="9"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockSharesAuthorized" xlink:label="loc_us-gaap_CommonStockSharesAuthorized_316"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_309" xlink:to="loc_us-gaap_CommonStockSharesAuthorized_316" use="optional" order="10"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockSharesIssued" xlink:label="loc_us-gaap_CommonStockSharesIssued_317"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_309" xlink:to="loc_us-gaap_CommonStockSharesIssued_317" use="optional" order="11"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TreasuryStockShares" xlink:label="loc_us-gaap_TreasuryStockShares_318"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_309" xlink:to="loc_us-gaap_TreasuryStockShares_318" use="optional" order="12"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockSharesOutstanding" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_365787"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_309" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_365787" use="optional" order="13"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/ConsolidatedStatementsOfOperationsAndComprehensiveLoss">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_562"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EarningsPerShareBasicAndDiluted" xlink:label="loc_us-gaap_EarningsPerShareBasicAndDiluted_574"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_562" xlink:to="loc_us-gaap_EarningsPerShareBasicAndDiluted_574" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_WeightedAverageNumberOfShareOutstandingBasicAndDiluted" xlink:label="loc_us-gaap_WeightedAverageNumberOfShareOutstandingBasicAndDiluted_575"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_562" xlink:to="loc_us-gaap_WeightedAverageNumberOfShareOutstandingBasicAndDiluted_575" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_560"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_562" xlink:to="loc_us-gaap_StatementTable_560" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_dei_LegalEntityAxis_561"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_560" xlink:to="loc_dei_LegalEntityAxis_561" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_565"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_561" xlink:to="loc_dei_EntityDomain_565" use="optional" order="5"/>
<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_565_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_561" xlink:to="loc_dei_EntityDomain_565_default" use="optional" order="6"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ProductOrServiceAxis" xlink:label="loc_srt_ProductOrServiceAxis_367115"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_560" xlink:to="loc_srt_ProductOrServiceAxis_367115" use="optional" order="7"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ProductsAndServicesDomain" xlink:label="loc_srt_ProductsAndServicesDomain_367116"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_367115" xlink:to="loc_srt_ProductsAndServicesDomain_367116" use="optional" order="8"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ProductsAndServicesDomain" xlink:label="loc_srt_ProductsAndServicesDomain_367116_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_367115" xlink:to="loc_srt_ProductsAndServicesDomain_367116_default" use="optional" order="9"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_ProductSalesMember" xlink:label="loc_casi_ProductSalesMember_367117"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_367116" xlink:to="loc_casi_ProductSalesMember_367117" use="optional" order="10"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevenuesAbstract" xlink:label="loc_us-gaap_RevenuesAbstract_563"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_562" xlink:to="loc_us-gaap_RevenuesAbstract_563" use="optional" order="11"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_Revenues" xlink:label="loc_us-gaap_Revenues_567"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_563" xlink:to="loc_us-gaap_Revenues_567" use="optional" order="12"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CostsAndExpensesAbstract" xlink:label="loc_us-gaap_CostsAndExpensesAbstract_564"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_562" xlink:to="loc_us-gaap_CostsAndExpensesAbstract_564" use="optional" order="13"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GeneralAndAdministrativeExpense" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_569"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_564" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_569" use="optional" order="14"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CostsAndExpenses" xlink:label="loc_us-gaap_CostsAndExpenses_570"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_564" xlink:to="loc_us-gaap_CostsAndExpenses_570" use="optional" order="15"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ResearchAndDevelopmentInProcess" xlink:label="loc_us-gaap_ResearchAndDevelopmentInProcess_365796"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_564" xlink:to="loc_us-gaap_ResearchAndDevelopmentInProcess_365796" use="optional" order="16"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ResearchAndDevelopmentExpense" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_367740"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_564" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_367740" use="optional" order="17"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InterestIncomeExpenseNet" xlink:label="loc_us-gaap_InterestIncomeExpenseNet_571"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_562" xlink:to="loc_us-gaap_InterestIncomeExpenseNet_571" use="optional" order="18"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncreaseDecreaseInDerivativeLiabilities" xlink:label="loc_us-gaap_IncreaseDecreaseInDerivativeLiabilities_572"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_562" xlink:to="loc_us-gaap_IncreaseDecreaseInDerivativeLiabilities_572" use="optional" order="19"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_573"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_562" xlink:to="loc_us-gaap_NetIncomeLoss_573" use="optional" order="20"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AssetsFairValueAdjustment" xlink:label="loc_us-gaap_AssetsFairValueAdjustment_365797"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_562" xlink:to="loc_us-gaap_AssetsFairValueAdjustment_365797" use="optional" order="21"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementOfIncomeAndComprehensiveIncomeAbstract" xlink:label="loc_us-gaap_StatementOfIncomeAndComprehensiveIncomeAbstract_365802"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_562" xlink:to="loc_us-gaap_StatementOfIncomeAndComprehensiveIncomeAbstract_365802" use="optional" order="22"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent" xlink:label="loc_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent_365805"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementOfIncomeAndComprehensiveIncomeAbstract_365802" xlink:to="loc_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent_365805" use="optional" order="23"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ComprehensiveIncomeNetOfTax" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTax_365807"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementOfIncomeAndComprehensiveIncomeAbstract_365802" xlink:to="loc_us-gaap_ComprehensiveIncomeNetOfTax_365807" use="optional" order="24"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/ConsolidatedStatementsOfStockholdersEquity">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_599"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_596"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_599" xlink:to="loc_us-gaap_StatementTable_596" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_597"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_596" xlink:to="loc_us-gaap_StatementClassOfStockAxis_597" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_598"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_597" xlink:to="loc_us-gaap_ClassOfStockDomain_598" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_598_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_597" xlink:to="loc_us-gaap_ClassOfStockDomain_598_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PreferredStockMember" xlink:label="loc_us-gaap_PreferredStockMember_600"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_598" xlink:to="loc_us-gaap_PreferredStockMember_600" use="optional" order="5"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember_601"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_598" xlink:to="loc_us-gaap_CommonStockMember_601" use="optional" order="6"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TreasuryStockMember" xlink:label="loc_us-gaap_TreasuryStockMember_602"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_598" xlink:to="loc_us-gaap_TreasuryStockMember_602" use="optional" order="7"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_603"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_598" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_603" use="optional" order="8"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetainedEarningsMember" xlink:label="loc_us-gaap_RetainedEarningsMember_604"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_598" xlink:to="loc_us-gaap_RetainedEarningsMember_604" use="optional" order="9"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PartnerCapitalComponentsAxis" xlink:label="loc_us-gaap_PartnerCapitalComponentsAxis_365813"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_596" xlink:to="loc_us-gaap_PartnerCapitalComponentsAxis_365813" use="optional" order="10"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PartnerCapitalComponentsDomain" xlink:label="loc_us-gaap_PartnerCapitalComponentsDomain_365814"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PartnerCapitalComponentsAxis_365813" xlink:to="loc_us-gaap_PartnerCapitalComponentsDomain_365814" use="optional" order="11"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PartnerCapitalComponentsDomain" xlink:label="loc_us-gaap_PartnerCapitalComponentsDomain_365814_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PartnerCapitalComponentsAxis_365813" xlink:to="loc_us-gaap_PartnerCapitalComponentsDomain_365814_default" use="optional" order="12"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_365815"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PartnerCapitalComponentsDomain_365814" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_365815" use="optional" order="13"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="loc_us-gaap_StockholdersEquity_605"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_599" xlink:to="loc_us-gaap_StockholdersEquity_605" use="optional" order="14"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharesOutstanding" xlink:label="loc_us-gaap_SharesOutstanding_606"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_599" xlink:to="loc_us-gaap_SharesOutstanding_606" use="optional" order="15"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueOther" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueOther_607"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_599" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueOther_607" use="optional" order="16"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesOther" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesOther_608"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_599" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesOther_608" use="optional" order="17"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_StockIssuedDuringPeriodValuesExerciseOfContingentPurchaseRight" xlink:label="loc_casi_StockIssuedDuringPeriodValuesExerciseOfContingentPurchaseRight_609"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_599" xlink:to="loc_casi_StockIssuedDuringPeriodValuesExerciseOfContingentPurchaseRight_609" use="optional" order="18"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_StockIssuedDuringPeriodSharesExerciseOfContingentPurchaseRight" xlink:label="loc_casi_StockIssuedDuringPeriodSharesExerciseOfContingentPurchaseRight_610"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_599" xlink:to="loc_casi_StockIssuedDuringPeriodSharesExerciseOfContingentPurchaseRight_610" use="optional" order="19"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_611"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_599" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_611" use="optional" order="20"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_612"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_599" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_612" use="optional" order="21"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_AdjustmentsToAdditionalPaidInCapitalPartialSettlementOfContingentPurchaseRightsDerivative" xlink:label="loc_casi_AdjustmentsToAdditionalPaidInCapitalPartialSettlementOfContingentPurchaseRightsDerivative_613"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_599" xlink:to="loc_casi_AdjustmentsToAdditionalPaidInCapitalPartialSettlementOfContingentPurchaseRightsDerivative_613" use="optional" order="22"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts_614"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_599" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts_614" use="optional" order="23"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_615"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_599" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_615" use="optional" order="24"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_616"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_599" xlink:to="loc_us-gaap_NetIncomeLoss_616" use="optional" order="25"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CumulativeEffectOnRetainedEarningsNetOfTax1" xlink:label="loc_us-gaap_CumulativeEffectOnRetainedEarningsNetOfTax1_365809"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_599" xlink:to="loc_us-gaap_CumulativeEffectOnRetainedEarningsNetOfTax1_365809" use="optional" order="26"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationStockOptionsRequisiteServicePeriodRecognition" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationStockOptionsRequisiteServicePeriodRecognition_365810"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_599" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationStockOptionsRequisiteServicePeriodRecognition_365810" use="optional" order="27"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherComprehensiveIncomeForeignCurrencyTranslationGainLossArisingDuringPeriodTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeForeignCurrencyTranslationGainLossArisingDuringPeriodTax_365811"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_599" xlink:to="loc_us-gaap_OtherComprehensiveIncomeForeignCurrencyTranslationGainLossArisingDuringPeriodTax_365811" use="optional" order="28"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_ShareBasedCompensationArrangementByShareBasedPaymentAwardWarrantsExercisesInPeriod" xlink:label="loc_casi_ShareBasedCompensationArrangementByShareBasedPaymentAwardWarrantsExercisesInPeriod_365841"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_599" xlink:to="loc_casi_ShareBasedCompensationArrangementByShareBasedPaymentAwardWarrantsExercisesInPeriod_365841" use="optional" order="29"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_StockIssuedDuringPeriodValueWarrantsExercised1" xlink:label="loc_casi_StockIssuedDuringPeriodValueWarrantsExercised1_365842"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_599" xlink:to="loc_casi_StockIssuedDuringPeriodValueWarrantsExercised1_365842" use="optional" order="30"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/ConsolidatedStatementsOfCashFlows">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_623"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_621"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_623" xlink:to="loc_us-gaap_StatementTable_621" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_dei_LegalEntityAxis_622"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_621" xlink:to="loc_dei_LegalEntityAxis_622" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_632"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_622" xlink:to="loc_dei_EntityDomain_632" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_632_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_622" xlink:to="loc_dei_EntityDomain_632_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_624"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_623" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_624" use="optional" order="5"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_633"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_624" xlink:to="loc_us-gaap_NetIncomeLoss_633" use="optional" order="6"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:label="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_625"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_624" xlink:to="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_625" use="optional" order="7"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DepreciationAndAmortization" xlink:label="loc_us-gaap_DepreciationAndAmortization_634"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_625" xlink:to="loc_us-gaap_DepreciationAndAmortization_634" use="optional" order="8"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GainLossOnDispositionOfAssets" xlink:label="loc_us-gaap_GainLossOnDispositionOfAssets_635"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_625" xlink:to="loc_us-gaap_GainLossOnDispositionOfAssets_635" use="optional" order="9"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensation" xlink:label="loc_us-gaap_ShareBasedCompensation_636"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_625" xlink:to="loc_us-gaap_ShareBasedCompensation_636" use="optional" order="10"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PaidInKindInterest" xlink:label="loc_us-gaap_PaidInKindInterest_637"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_625" xlink:to="loc_us-gaap_PaidInKindInterest_637" use="optional" order="11"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncreaseDecreaseInDerivativeLiabilities" xlink:label="loc_us-gaap_IncreaseDecreaseInDerivativeLiabilities_638"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_625" xlink:to="loc_us-gaap_IncreaseDecreaseInDerivativeLiabilities_638" use="optional" order="12"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:label="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_626"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_625" xlink:to="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_626" use="optional" order="13"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" xlink:label="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_639"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_626" xlink:to="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_639" use="optional" order="14"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsPayable" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsPayable_640"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_626" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsPayable_640" use="optional" order="15"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsPayableRelatedParties" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsPayableRelatedParties_641"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_626" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsPayableRelatedParties_641" use="optional" order="16"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncreaseDecreaseInAccruedLiabilities" xlink:label="loc_us-gaap_IncreaseDecreaseInAccruedLiabilities_642"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_626" xlink:to="loc_us-gaap_IncreaseDecreaseInAccruedLiabilities_642" use="optional" order="17"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AmortizationOfIntangibleAssets" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_365821"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_625" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_365821" use="optional" order="18"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AssetsFairValueAdjustment" xlink:label="loc_us-gaap_AssetsFairValueAdjustment_365824"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_625" xlink:to="loc_us-gaap_AssetsFairValueAdjustment_365824" use="optional" order="19"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_ResearchAndDevelopmentInProcessAcquired" xlink:label="loc_casi_ResearchAndDevelopmentInProcessAcquired_370967"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_625" xlink:to="loc_casi_ResearchAndDevelopmentInProcessAcquired_370967" use="optional" order="20"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_643"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_624" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_643" use="optional" order="21"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_627"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_623" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_627" use="optional" order="22"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:label="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_644"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_627" xlink:to="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_644" use="optional" order="23"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment" xlink:label="loc_us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment_645"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_627" xlink:to="loc_us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment_645" use="optional" order="24"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_646"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_627" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_646" use="optional" order="25"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PaymentsToAcquireIntangibleAssets" xlink:label="loc_us-gaap_PaymentsToAcquireIntangibleAssets_365830"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_627" xlink:to="loc_us-gaap_PaymentsToAcquireIntangibleAssets_365830" use="optional" order="26"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_628"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_623" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_628" use="optional" order="27"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PaymentsOfStockIssuanceCosts" xlink:label="loc_us-gaap_PaymentsOfStockIssuanceCosts_647"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_628" xlink:to="loc_us-gaap_PaymentsOfStockIssuanceCosts_647" use="optional" order="28"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_ProceedsFromIssuanceOfCommonStockAndWarrants" xlink:label="loc_casi_ProceedsFromIssuanceOfCommonStockAndWarrants_648"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_628" xlink:to="loc_casi_ProceedsFromIssuanceOfCommonStockAndWarrants_648" use="optional" order="29"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ProceedsFromStockOptionsExercised" xlink:label="loc_us-gaap_ProceedsFromStockOptionsExercised_649"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_628" xlink:to="loc_us-gaap_ProceedsFromStockOptionsExercised_649" use="optional" order="30"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_650"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_628" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_650" use="optional" order="31"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation" xlink:label="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_365831"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_628" xlink:to="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_365831" use="optional" order="32"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ProceedsFromWarrantExercises" xlink:label="loc_us-gaap_ProceedsFromWarrantExercises_365832"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_628" xlink:to="loc_us-gaap_ProceedsFromWarrantExercises_365832" use="optional" order="33"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease" xlink:label="loc_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease_651"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_623" xlink:to="loc_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease_651" use="optional" order="34"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_652"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_623" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_652" use="optional" order="35"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SupplementalCashFlowInformationAbstract" xlink:label="loc_us-gaap_SupplementalCashFlowInformationAbstract_629"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_623" xlink:to="loc_us-gaap_SupplementalCashFlowInformationAbstract_629" use="optional" order="36"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract" xlink:label="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_630"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract_629" xlink:to="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_630" use="optional" order="37"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_WarrantIssuedToPlacementAgent" xlink:label="loc_casi_WarrantIssuedToPlacementAgent_654"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_630" xlink:to="loc_casi_WarrantIssuedToPlacementAgent_654" use="optional" order="38"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements_655"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_630" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements_655" use="optional" order="39"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_CashFlowNoncashInvestingActivitiesDisclosureAbstract" xlink:label="loc_casi_CashFlowNoncashInvestingActivitiesDisclosureAbstract_631"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract_629" xlink:to="loc_casi_CashFlowNoncashInvestingActivitiesDisclosureAbstract_631" use="optional" order="40"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_DisposalOfFullyDepreciatedPropertyAndEquipmentAtCost" xlink:label="loc_casi_DisposalOfFullyDepreciatedPropertyAndEquipmentAtCost_656"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_casi_CashFlowNoncashInvestingActivitiesDisclosureAbstract_631" xlink:to="loc_casi_DisposalOfFullyDepreciatedPropertyAndEquipmentAtCost_656" use="optional" order="41"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InterestPaid" xlink:label="loc_us-gaap_InterestPaid_365834"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract_629" xlink:to="loc_us-gaap_InterestPaid_365834" use="optional" order="42"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxesPaidNet" xlink:label="loc_us-gaap_IncomeTaxesPaidNet_365835"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract_629" xlink:to="loc_us-gaap_IncomeTaxesPaidNet_365835" use="optional" order="43"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents" xlink:label="loc_us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents_365833"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_623" xlink:to="loc_us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents_365833" use="optional" order="44"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/FairValueMeasurementsTables">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_56"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable_53"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_56" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable_53" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_54"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable_53" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_54" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_55"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_54" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_55" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_55_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_54" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_55_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_57"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_55" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_57" use="optional" order="5"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock_366047"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_56" xlink:to="loc_us-gaap_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock_366047" use="optional" order="6"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock_366072"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_56" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock_366072" use="optional" order="7"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/DescriptionOfBusinessDetailsTextual">
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_DescriptionOfBusinessAndBasisOfPresentationLineItems" xlink:label="loc_casi_DescriptionOfBusinessAndBasisOfPresentationLineItems_91"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_SheduleOfDescriptionOfBusinessAndBasisOfPresentationTable" xlink:label="loc_casi_SheduleOfDescriptionOfBusinessAndBasisOfPresentationTable_78"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_casi_DescriptionOfBusinessAndBasisOfPresentationLineItems_91" xlink:to="loc_casi_SheduleOfDescriptionOfBusinessAndBasisOfPresentationTable_78" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_dei_LegalEntityAxis_79"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_casi_SheduleOfDescriptionOfBusinessAndBasisOfPresentationTable_78" xlink:to="loc_dei_LegalEntityAxis_79" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_80"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_79" xlink:to="loc_dei_EntityDomain_80" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_80_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_79" xlink:to="loc_dei_EntityDomain_80_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementScenarioAxis" xlink:label="loc_us-gaap_StatementScenarioAxis_81"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_casi_SheduleOfDescriptionOfBusinessAndBasisOfPresentationTable_78" xlink:to="loc_us-gaap_StatementScenarioAxis_81" use="optional" order="5"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_82"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementScenarioAxis_81" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_82" use="optional" order="6"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_82_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementScenarioAxis_81" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_82_default" use="optional" order="7"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_83"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_casi_SheduleOfDescriptionOfBusinessAndBasisOfPresentationTable_78" xlink:to="loc_us-gaap_StatementClassOfStockAxis_83" use="optional" order="8"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_94"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_83" xlink:to="loc_us-gaap_ClassOfStockDomain_94" use="optional" order="9"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_94_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_83" xlink:to="loc_us-gaap_ClassOfStockDomain_94_default" use="optional" order="10"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_StockIssuedAxis" xlink:label="loc_casi_StockIssuedAxis_84"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_casi_SheduleOfDescriptionOfBusinessAndBasisOfPresentationTable_78" xlink:to="loc_casi_StockIssuedAxis_84" use="optional" order="11"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_StockIssuedDomain" xlink:label="loc_casi_StockIssuedDomain_95"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_casi_StockIssuedAxis_84" xlink:to="loc_casi_StockIssuedDomain_95" use="optional" order="12"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_StockIssuedDomain" xlink:label="loc_casi_StockIssuedDomain_95_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_casi_StockIssuedAxis_84" xlink:to="loc_casi_StockIssuedDomain_95_default" use="optional" order="13"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_85"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_casi_SheduleOfDescriptionOfBusinessAndBasisOfPresentationTable_78" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_85" use="optional" order="14"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_86"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_85" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_86" use="optional" order="15"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_86_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_85" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_86_default" use="optional" order="16"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaap_SubsequentEventMember_96"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_86" xlink:to="loc_us-gaap_SubsequentEventMember_96" use="optional" order="17"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsidiarySaleOfStockAxis" xlink:label="loc_us-gaap_SubsidiarySaleOfStockAxis_87"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_casi_SheduleOfDescriptionOfBusinessAndBasisOfPresentationTable_78" xlink:to="loc_us-gaap_SubsidiarySaleOfStockAxis_87" use="optional" order="18"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SaleOfStockNameOfTransactionDomain" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_88"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_87" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_88" use="optional" order="19"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SaleOfStockNameOfTransactionDomain" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_88_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_87" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_88_default" use="optional" order="20"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PrivatePlacementMember" xlink:label="loc_us-gaap_PrivatePlacementMember_98"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_88" xlink:to="loc_us-gaap_PrivatePlacementMember_98" use="optional" order="21"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_365845"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_casi_SheduleOfDescriptionOfBusinessAndBasisOfPresentationTable_78" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_365845" use="optional" order="22"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_365846"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_365845" xlink:to="loc_us-gaap_SegmentDomain_365846" use="optional" order="23"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_365846_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_365845" xlink:to="loc_us-gaap_SegmentDomain_365846_default" use="optional" order="24"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_CASIWuxiMember" xlink:label="loc_casi_CASIWuxiMember_365847"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_365846" xlink:to="loc_casi_CASIWuxiMember_365847" use="optional" order="25"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_365851"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_casi_SheduleOfDescriptionOfBusinessAndBasisOfPresentationTable_78" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_365851" use="optional" order="26"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaap_RelatedPartyDomain_365852"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_365851" xlink:to="loc_us-gaap_RelatedPartyDomain_365852" use="optional" order="27"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaap_RelatedPartyDomain_365852_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_365851" xlink:to="loc_us-gaap_RelatedPartyDomain_365852_default" use="optional" order="28"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InvestorMember" xlink:label="loc_us-gaap_InvestorMember_365853"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_365852" xlink:to="loc_us-gaap_InvestorMember_365853" use="optional" order="29"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_100"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_casi_DescriptionOfBusinessAndBasisOfPresentationLineItems_91" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_100" use="optional" order="30"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_StockToBeIssuedShares" xlink:label="loc_casi_StockToBeIssuedShares_108"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_casi_DescriptionOfBusinessAndBasisOfPresentationLineItems_91" xlink:to="loc_casi_StockToBeIssuedShares_108" use="optional" order="31"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_StockAndWarrantsToBeIssuedValue" xlink:label="loc_casi_StockAndWarrantsToBeIssuedValue_109"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_casi_DescriptionOfBusinessAndBasisOfPresentationLineItems_91" xlink:to="loc_casi_StockAndWarrantsToBeIssuedValue_109" use="optional" order="32"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_WarrantsToBeIssued" xlink:label="loc_casi_WarrantsToBeIssued_365854"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_casi_DescriptionOfBusinessAndBasisOfPresentationLineItems_91" xlink:to="loc_casi_WarrantsToBeIssued_365854" use="optional" order="33"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_ProceedsFromIssuanceOfCommonStockAndWarrantsGross" xlink:label="loc_casi_ProceedsFromIssuanceOfCommonStockAndWarrantsGross_365855"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_casi_DescriptionOfBusinessAndBasisOfPresentationLineItems_91" xlink:to="loc_casi_ProceedsFromIssuanceOfCommonStockAndWarrantsGross_365855" use="optional" order="34"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_365858"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_casi_DescriptionOfBusinessAndBasisOfPresentationLineItems_91" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_365858" use="optional" order="35"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_NumberOfWarrantsToPurchaseCommonStockIssuedDuringThePeriod" xlink:label="loc_casi_NumberOfWarrantsToPurchaseCommonStockIssuedDuringThePeriod_365860"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_casi_DescriptionOfBusinessAndBasisOfPresentationLineItems_91" xlink:to="loc_casi_NumberOfWarrantsToPurchaseCommonStockIssuedDuringThePeriod_365860" use="optional" order="36"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_InitialCashInvestment" xlink:label="loc_casi_InitialCashInvestment_365849"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_casi_DescriptionOfBusinessAndBasisOfPresentationLineItems_91" xlink:to="loc_casi_InitialCashInvestment_365849" use="optional" order="37"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_TotalFutureInvestment" xlink:label="loc_casi_TotalFutureInvestment_373085"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_casi_DescriptionOfBusinessAndBasisOfPresentationLineItems_91" xlink:to="loc_casi_TotalFutureInvestment_373085" use="optional" order="38"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/SummaryOfSignificantAccountingPoliciesDetailsTextual">
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_AccountingPoliciesLineItems" xlink:label="loc_casi_AccountingPoliciesLineItems_133"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_AccountingPoliciesTable" xlink:label="loc_casi_AccountingPoliciesTable_123"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_casi_AccountingPoliciesLineItems_133" xlink:to="loc_casi_AccountingPoliciesTable_123" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_126"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_casi_AccountingPoliciesTable_123" xlink:to="loc_srt_RangeAxis_126" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_127"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_126" xlink:to="loc_srt_RangeMember_127" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_127_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_126" xlink:to="loc_srt_RangeMember_127_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MinimumMember" xlink:label="loc_srt_MinimumMember_136"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_127" xlink:to="loc_srt_MinimumMember_136" use="optional" order="5"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MaximumMember" xlink:label="loc_srt_MaximumMember_137"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_127" xlink:to="loc_srt_MaximumMember_137" use="optional" order="6"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_129"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_casi_AccountingPoliciesTable_123" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_129" use="optional" order="7"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_139"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_129" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_139" use="optional" order="8"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_139_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_129" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_139_default" use="optional" order="9"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_130"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_casi_AccountingPoliciesTable_123" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_130" use="optional" order="10"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_131"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_130" xlink:to="loc_us-gaap_EquityComponentDomain_131" use="optional" order="11"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_131_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_130" xlink:to="loc_us-gaap_EquityComponentDomain_131_default" use="optional" order="12"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_OptionsAndWarrantsMember" xlink:label="loc_casi_OptionsAndWarrantsMember_140"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_131" xlink:to="loc_casi_OptionsAndWarrantsMember_140" use="optional" order="13"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_132"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_casi_AccountingPoliciesTable_123" xlink:to="loc_us-gaap_AwardTypeAxis_132" use="optional" order="14"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_141"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_132" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_141" use="optional" order="15"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_141_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_132" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_141_default" use="optional" order="16"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:label="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_366043"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_casi_AccountingPoliciesTable_123" xlink:to="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_366043" use="optional" order="17"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="loc_us-gaap_TypeOfAdoptionMember_366044"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_366043" xlink:to="loc_us-gaap_TypeOfAdoptionMember_366044" use="optional" order="18"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="loc_us-gaap_TypeOfAdoptionMember_366044_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_366043" xlink:to="loc_us-gaap_TypeOfAdoptionMember_366044_default" use="optional" order="19"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccountingStandardsUpdate201602Member" xlink:label="loc_us-gaap_AccountingStandardsUpdate201602Member_366045"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfAdoptionMember_366044" xlink:to="loc_us-gaap_AccountingStandardsUpdate201602Member_366045" use="optional" order="20"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_ClinicalTrialAccruals" xlink:label="loc_casi_ClinicalTrialAccruals_142"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_casi_AccountingPoliciesLineItems_133" xlink:to="loc_casi_ClinicalTrialAccruals_142" use="optional" order="21"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_146"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_casi_AccountingPoliciesLineItems_133" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_146" use="optional" order="22"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InventoryGross" xlink:label="loc_us-gaap_InventoryGross_366078"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_casi_AccountingPoliciesLineItems_133" xlink:to="loc_us-gaap_InventoryGross_366078" use="optional" order="23"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CumulativeEffectOnRetainedEarningsNetOfTax1" xlink:label="loc_us-gaap_CumulativeEffectOnRetainedEarningsNetOfTax1_373089"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_casi_AccountingPoliciesLineItems_133" xlink:to="loc_us-gaap_CumulativeEffectOnRetainedEarningsNetOfTax1_373089" use="optional" order="24"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_OperatingLeaseRightOfUseAssetLiability" xlink:label="loc_casi_OperatingLeaseRightOfUseAssetLiability_373093"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_casi_AccountingPoliciesLineItems_133" xlink:to="loc_casi_OperatingLeaseRightOfUseAssetLiability_373093" use="optional" order="25"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/AcquisitionOfAbbreviatedNewDrugApplicationsFromSandozDetails">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_366139"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_366136"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_366139" xlink:to="loc_us-gaap_StatementTable_366136" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_366137"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_366136" xlink:to="loc_us-gaap_StatementClassOfStockAxis_366137" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_366138"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_366137" xlink:to="loc_us-gaap_ClassOfStockDomain_366138" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_366138_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_366137" xlink:to="loc_us-gaap_ClassOfStockDomain_366138_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_366142"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_366136" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_366142" use="optional" order="5"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_366143"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_366142" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_366143" use="optional" order="6"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_366143_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_366142" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_366143_default" use="optional" order="7"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_AbbreviatedNewDrugApplicationsMember" xlink:label="loc_casi_AbbreviatedNewDrugApplicationsMember_366145"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_366143" xlink:to="loc_casi_AbbreviatedNewDrugApplicationsMember_366145" use="optional" order="8"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_ActivePharmaceuticalIngredientMember" xlink:label="loc_casi_ActivePharmaceuticalIngredientMember_366152"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_366143" xlink:to="loc_casi_ActivePharmaceuticalIngredientMember_366152" use="optional" order="9"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_PurchasePriceForFiniteLivedIntangibleAssetsAcquired" xlink:label="loc_casi_PurchasePriceForFiniteLivedIntangibleAssetsAcquired_366150"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_366139" xlink:to="loc_casi_PurchasePriceForFiniteLivedIntangibleAssetsAcquired_366150" use="optional" order="10"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/AcquisitionOfAbbreviatedNewDrugApplicationsFromSandozDetailsTextual">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_366159"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_366156"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_366159" xlink:to="loc_us-gaap_StatementTable_366156" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_366157"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_366156" xlink:to="loc_us-gaap_StatementClassOfStockAxis_366157" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_366158"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_366157" xlink:to="loc_us-gaap_ClassOfStockDomain_366158" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_366158_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_366157" xlink:to="loc_us-gaap_ClassOfStockDomain_366158_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_366162"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_366156" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_366162" use="optional" order="5"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_366163"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_366162" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_366163" use="optional" order="6"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_366163_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_366162" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_366163_default" use="optional" order="7"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_AbbreviatedNewDrugApplicationsMember" xlink:label="loc_casi_AbbreviatedNewDrugApplicationsMember_366164"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_366163" xlink:to="loc_casi_AbbreviatedNewDrugApplicationsMember_366164" use="optional" order="8"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_ActivePharmaceuticalIngredientMember" xlink:label="loc_casi_ActivePharmaceuticalIngredientMember_366165"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_366163" xlink:to="loc_casi_ActivePharmaceuticalIngredientMember_366165" use="optional" order="9"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:label="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_366167"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_366156" xlink:to="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_366167" use="optional" order="10"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="loc_us-gaap_TypeOfAdoptionMember_366168"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_366167" xlink:to="loc_us-gaap_TypeOfAdoptionMember_366168" use="optional" order="11"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="loc_us-gaap_TypeOfAdoptionMember_366168_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_366167" xlink:to="loc_us-gaap_TypeOfAdoptionMember_366168_default" use="optional" order="12"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ResearchAndDevelopmentInProcess" xlink:label="loc_us-gaap_ResearchAndDevelopmentInProcess_366170"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_366159" xlink:to="loc_us-gaap_ResearchAndDevelopmentInProcess_366170" use="optional" order="13"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_AssetAcquisitionTransactionCosts" xlink:label="loc_casi_AssetAcquisitionTransactionCosts_366171"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_366159" xlink:to="loc_casi_AssetAcquisitionTransactionCosts_366171" use="optional" order="14"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_366172"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_366159" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_366172" use="optional" order="15"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PaymentsToAcquireIntangibleAssets" xlink:label="loc_us-gaap_PaymentsToAcquireIntangibleAssets_366173"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_366159" xlink:to="loc_us-gaap_PaymentsToAcquireIntangibleAssets_366173" use="optional" order="16"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/AcquisitionOfAbbreviatedNewDrugApplicationFromLaurusLabsDetailsTextual">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_366505"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_366502"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_366505" xlink:to="loc_us-gaap_StatementTable_366502" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_366503"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_366502" xlink:to="loc_us-gaap_StatementClassOfStockAxis_366503" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_366504"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_366503" xlink:to="loc_us-gaap_ClassOfStockDomain_366504" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_366504_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_366503" xlink:to="loc_us-gaap_ClassOfStockDomain_366504_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_366506"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_366502" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_366506" use="optional" order="5"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_366507"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_366506" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_366507" use="optional" order="6"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_366507_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_366506" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_366507_default" use="optional" order="7"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_LaurusLabMember" xlink:label="loc_casi_LaurusLabMember_366508"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_366507" xlink:to="loc_casi_LaurusLabMember_366508" use="optional" order="8"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_366515"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_366502" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_366515" use="optional" order="9"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_366516"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_366515" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_366516" use="optional" order="10"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_366516_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_366515" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_366516_default" use="optional" order="11"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_AbbreviatedNewDrugApplicationsMember" xlink:label="loc_casi_AbbreviatedNewDrugApplicationsMember_366518"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_366516" xlink:to="loc_casi_AbbreviatedNewDrugApplicationsMember_366518" use="optional" order="12"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_PurchasePriceOfDrug" xlink:label="loc_casi_PurchasePriceOfDrug_366509"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_366505" xlink:to="loc_casi_PurchasePriceOfDrug_366509" use="optional" order="13"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_UpfrontPaymentForDrug" xlink:label="loc_casi_UpfrontPaymentForDrug_366510"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_366505" xlink:to="loc_casi_UpfrontPaymentForDrug_366510" use="optional" order="14"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_AssetAcquisitionTransactionCosts" xlink:label="loc_casi_AssetAcquisitionTransactionCosts_366512"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_366505" xlink:to="loc_casi_AssetAcquisitionTransactionCosts_366512" use="optional" order="15"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_ContingentConsiderationPaid" xlink:label="loc_casi_ContingentConsiderationPaid_366513"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_366505" xlink:to="loc_casi_ContingentConsiderationPaid_366513" use="optional" order="16"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_366514"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_366505" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_366514" use="optional" order="17"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_RemainingAmountOfFutureContingentConsideration" xlink:label="loc_casi_RemainingAmountOfFutureContingentConsideration_373197"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_366505" xlink:to="loc_casi_RemainingAmountOfFutureContingentConsideration_373197" use="optional" order="18"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/InvestmentInEquitySecuritiesDetails">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_366531"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_366528"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_366531" xlink:to="loc_us-gaap_StatementTable_366528" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_366529"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_366528" xlink:to="loc_us-gaap_StatementClassOfStockAxis_366529" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_366530"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_366529" xlink:to="loc_us-gaap_ClassOfStockDomain_366530" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_366530_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_366529" xlink:to="loc_us-gaap_ClassOfStockDomain_366530_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_366532"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_366528" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_366532" use="optional" order="5"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_366533"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_366532" xlink:to="loc_us-gaap_EquityComponentDomain_366533" use="optional" order="6"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_366533_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_366532" xlink:to="loc_us-gaap_EquityComponentDomain_366533_default" use="optional" order="7"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember_366534"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_366533" xlink:to="loc_us-gaap_CommonStockMember_366534" use="optional" order="8"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AvailableForSaleEquitySecuritiesAmortizedCostBasis" xlink:label="loc_us-gaap_AvailableForSaleEquitySecuritiesAmortizedCostBasis_366535"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_366531" xlink:to="loc_us-gaap_AvailableForSaleEquitySecuritiesAmortizedCostBasis_366535" use="optional" order="9"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AvailableForSaleEquitySecuritiesGrossUnrealizedGain" xlink:label="loc_us-gaap_AvailableForSaleEquitySecuritiesGrossUnrealizedGain_366536"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_366531" xlink:to="loc_us-gaap_AvailableForSaleEquitySecuritiesGrossUnrealizedGain_366536" use="optional" order="10"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InvestmentsFairValueDisclosure" xlink:label="loc_us-gaap_InvestmentsFairValueDisclosure_366537"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_366531" xlink:to="loc_us-gaap_InvestmentsFairValueDisclosure_366537" use="optional" order="11"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/InvestmentInEquitySecuritiesDetailsTextual">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_366544"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_366541"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_366544" xlink:to="loc_us-gaap_StatementTable_366541" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_366542"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_366541" xlink:to="loc_us-gaap_StatementClassOfStockAxis_366542" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_366543"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_366542" xlink:to="loc_us-gaap_ClassOfStockDomain_366543" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_366543_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_366542" xlink:to="loc_us-gaap_ClassOfStockDomain_366543_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_366546"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_366541" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_366546" use="optional" order="5"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_366547"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_366546" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_366547" use="optional" order="6"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_366547_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_366546" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_366547_default" use="optional" order="7"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:label="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_373726"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_366541" xlink:to="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_373726" use="optional" order="8"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="loc_us-gaap_TypeOfAdoptionMember_373727"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_373726" xlink:to="loc_us-gaap_TypeOfAdoptionMember_373727" use="optional" order="9"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="loc_us-gaap_TypeOfAdoptionMember_373727_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_373726" xlink:to="loc_us-gaap_TypeOfAdoptionMember_373727_default" use="optional" order="10"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccountingStandardsUpdate201601Member" xlink:label="loc_us-gaap_AccountingStandardsUpdate201601Member_373728"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfAdoptionMember_373727" xlink:to="loc_us-gaap_AccountingStandardsUpdate201601Member_373728" use="optional" order="11"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_373737"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_366541" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_373737" use="optional" order="12"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_373738"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_373737" xlink:to="loc_us-gaap_EquityComponentDomain_373738" use="optional" order="13"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_373738_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_373737" xlink:to="loc_us-gaap_EquityComponentDomain_373738_default" use="optional" order="14"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember_373739"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_373738" xlink:to="loc_us-gaap_CommonStockMember_373739" use="optional" order="15"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AssetsFairValueAdjustment" xlink:label="loc_us-gaap_AssetsFairValueAdjustment_366549"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_366544" xlink:to="loc_us-gaap_AssetsFairValueAdjustment_366549" use="optional" order="16"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityMethodInvestments" xlink:label="loc_us-gaap_EquityMethodInvestments_373706"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_366544" xlink:to="loc_us-gaap_EquityMethodInvestments_373706" use="optional" order="17"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityMethodInvestmentsFairValueDisclosure" xlink:label="loc_us-gaap_EquityMethodInvestmentsFairValueDisclosure_373723"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_366544" xlink:to="loc_us-gaap_EquityMethodInvestmentsFairValueDisclosure_373723" use="optional" order="18"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_373724"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_366544" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_373724" use="optional" order="19"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_373734"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_366544" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_373734" use="optional" order="20"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/PropertyAndEquipmentDetails">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_367667"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_367664"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_367667" xlink:to="loc_us-gaap_StatementTable_367664" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_367665"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_367664" xlink:to="loc_us-gaap_StatementClassOfStockAxis_367665" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_367666"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_367665" xlink:to="loc_us-gaap_ClassOfStockDomain_367666" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_367666_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_367665" xlink:to="loc_us-gaap_ClassOfStockDomain_367666_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_FurnitureAndEquipmentGross" xlink:label="loc_casi_FurnitureAndEquipmentGross_367668"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_367667" xlink:to="loc_casi_FurnitureAndEquipmentGross_367668" use="optional" order="5"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LeaseholdImprovementsGross" xlink:label="loc_us-gaap_LeaseholdImprovementsGross_367669"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_367667" xlink:to="loc_us-gaap_LeaseholdImprovementsGross_367669" use="optional" order="6"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_367670"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_367667" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_367670" use="optional" order="7"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_367672"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_367667" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_367672" use="optional" order="8"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_367751"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_367667" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_367751" use="optional" order="9"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/PropertyAndEquipmentDetailsTextual">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_372338"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_372335"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_372338" xlink:to="loc_us-gaap_StatementTable_372335" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_372336"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_372335" xlink:to="loc_us-gaap_StatementClassOfStockAxis_372336" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_372337"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_372336" xlink:to="loc_us-gaap_ClassOfStockDomain_372337" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_372337_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_372336" xlink:to="loc_us-gaap_ClassOfStockDomain_372337_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_372340"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_372335" xlink:to="loc_srt_RangeAxis_372340" use="optional" order="5"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_372341"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_372340" xlink:to="loc_srt_RangeMember_372341" use="optional" order="6"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_372341_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_372340" xlink:to="loc_srt_RangeMember_372341_default" use="optional" order="7"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MaximumMember" xlink:label="loc_srt_MaximumMember_372342"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_372341" xlink:to="loc_srt_MaximumMember_372342" use="optional" order="8"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MinimumMember" xlink:label="loc_srt_MinimumMember_372343"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_372341" xlink:to="loc_srt_MinimumMember_372343" use="optional" order="9"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DepreciationDepletionAndAmortization" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_372344"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_372338" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_372344" use="optional" order="10"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_372345"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_372338" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_372345" use="optional" order="11"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/IntangibleAssetsDetails">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_366584"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_366580"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_366584" xlink:to="loc_us-gaap_StatementTable_366580" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_366581"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_366580" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_366581" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_366582"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_366581" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_366582" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_366582_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_366581" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_366582_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_AbbreviatedNewDrugApplicationsMember" xlink:label="loc_casi_AbbreviatedNewDrugApplicationsMember_366583"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_366582" xlink:to="loc_casi_AbbreviatedNewDrugApplicationsMember_366583" use="optional" order="5"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_AbbreviatedNewDrugApplicationsTDFMember" xlink:label="loc_casi_AbbreviatedNewDrugApplicationsTDFMember_366588"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_366582" xlink:to="loc_casi_AbbreviatedNewDrugApplicationsTDFMember_366588" use="optional" order="6"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsGross" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_366585"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_366584" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_366585" use="optional" order="7"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_366586"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_366584" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_366586" use="optional" order="8"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_366587"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_366584" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_366587" use="optional" order="9"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/IntangibleAssetsDetails1">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_366596"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_366593"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_366596" xlink:to="loc_us-gaap_StatementTable_366593" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_367150"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_366593" xlink:to="loc_us-gaap_StatementClassOfStockAxis_367150" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_367151"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_367150" xlink:to="loc_us-gaap_ClassOfStockDomain_367151" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_367151_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_367150" xlink:to="loc_us-gaap_ClassOfStockDomain_367151_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_366597"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_366596" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_366597" use="optional" order="5"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_366598"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_366596" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_366598" use="optional" order="6"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_366599"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_366596" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_366599" use="optional" order="7"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive_366606"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_366596" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive_366606" use="optional" order="8"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive_366611"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_366596" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive_366611" use="optional" order="9"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear_367673"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_366596" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear_367673" use="optional" order="10"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/IntangibleAssetsDetailsTextual">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_366625"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_366622"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_366625" xlink:to="loc_us-gaap_StatementTable_366622" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:label="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_366626"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_366622" xlink:to="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_366626" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="loc_us-gaap_TypeOfAdoptionMember_366627"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_366626" xlink:to="loc_us-gaap_TypeOfAdoptionMember_366627" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="loc_us-gaap_TypeOfAdoptionMember_366627_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_366626" xlink:to="loc_us-gaap_TypeOfAdoptionMember_366627_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_366629"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_366625" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_366629" use="optional" order="5"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/EstablishmentOfCasiWuxiDetailsTextual">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_366646"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_366643"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_366646" xlink:to="loc_us-gaap_StatementTable_366643" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_dei_LegalEntityAxis_366647"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_366643" xlink:to="loc_dei_LegalEntityAxis_366647" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_366648"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_366647" xlink:to="loc_dei_EntityDomain_366648" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_366648_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_366647" xlink:to="loc_dei_EntityDomain_366648_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_CASIWuxiMember" xlink:label="loc_casi_CASIWuxiMember_366649"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_366648" xlink:to="loc_casi_CASIWuxiMember_366649" use="optional" order="5"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_366652"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_366643" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_366652" use="optional" order="6"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_366653"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_366652" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_366653" use="optional" order="7"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_366653_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_366652" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_366653_default" use="optional" order="8"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_AbbreviatedNewDrugApplicationsMember" xlink:label="loc_casi_AbbreviatedNewDrugApplicationsMember_366654"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_366653" xlink:to="loc_casi_AbbreviatedNewDrugApplicationsMember_366654" use="optional" order="9"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_367733"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_366643" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_367733" use="optional" order="10"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_367734"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_367733" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_367734" use="optional" order="11"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_367734_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_367733" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_367734_default" use="optional" order="12"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaap_SubsequentEventMember_367735"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_367734" xlink:to="loc_us-gaap_SubsequentEventMember_367735" use="optional" order="13"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_InvestmentCommitment" xlink:label="loc_casi_InvestmentCommitment_367728"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_366646" xlink:to="loc_casi_InvestmentCommitment_367728" use="optional" order="14"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_PaymentsToBePaidWithinThreeYears" xlink:label="loc_casi_PaymentsToBePaidWithinThreeYears_367738"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_366646" xlink:to="loc_casi_PaymentsToBePaidWithinThreeYears_367738" use="optional" order="15"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_FutureInvestment" xlink:label="loc_casi_FutureInvestment_372365"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_366646" xlink:to="loc_casi_FutureInvestment_372365" use="optional" order="16"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_SelectedAndasToBeTransferred" xlink:label="loc_casi_SelectedAndasToBeTransferred_372367"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_366646" xlink:to="loc_casi_SelectedAndasToBeTransferred_372367" use="optional" order="17"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_InitialCashInvestment" xlink:label="loc_casi_InitialCashInvestment_373170"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_366646" xlink:to="loc_casi_InitialCashInvestment_373170" use="optional" order="18"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/NotePayableDetailsTextual">
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_NotesPayableLineItems" xlink:label="loc_casi_NotesPayableLineItems_220"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_ScheduleOfNotesPayableTable" xlink:label="loc_casi_ScheduleOfNotesPayableTable_216"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_casi_NotesPayableLineItems_220" xlink:to="loc_casi_ScheduleOfNotesPayableTable_216" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_217"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_casi_ScheduleOfNotesPayableTable_216" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_217" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaap_RelatedPartyDomain_218"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_217" xlink:to="loc_us-gaap_RelatedPartyDomain_218" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaap_RelatedPartyDomain_218_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_217" xlink:to="loc_us-gaap_RelatedPartyDomain_218_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_SpectrumPharmaceuticalsMember" xlink:label="loc_casi_SpectrumPharmaceuticalsMember_221"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_218" xlink:to="loc_casi_SpectrumPharmaceuticalsMember_221" use="optional" order="5"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_219"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_casi_ScheduleOfNotesPayableTable_216" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_219" use="optional" order="6"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_222"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_219" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_222" use="optional" order="7"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_222_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_219" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_222_default" use="optional" order="8"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_224"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_casi_NotesPayableLineItems_220" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_224" use="optional" order="9"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_DebtInstrumentInitialDiscountUponIssuance" xlink:label="loc_casi_DebtInstrumentInitialDiscountUponIssuance_225"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_casi_NotesPayableLineItems_220" xlink:to="loc_casi_DebtInstrumentInitialDiscountUponIssuance_225" use="optional" order="10"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_226"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_casi_NotesPayableLineItems_220" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_226" use="optional" order="11"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InterestExpense" xlink:label="loc_us-gaap_InterestExpense_372358"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_casi_NotesPayableLineItems_220" xlink:to="loc_us-gaap_InterestExpense_372358" use="optional" order="12"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/StockholdersEquityDetails">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_477"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_474"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_477" xlink:to="loc_us-gaap_StatementTable_474" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_475"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_474" xlink:to="loc_us-gaap_StatementClassOfStockAxis_475" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_476"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_475" xlink:to="loc_us-gaap_ClassOfStockDomain_476" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_476_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_475" xlink:to="loc_us-gaap_ClassOfStockDomain_476_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_WarrantMember" xlink:label="loc_us-gaap_WarrantMember_478"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_476" xlink:to="loc_us-gaap_WarrantMember_478" use="optional" order="5"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityinstrumentsOtherThanOptionsOutstandingNumber" xlink:label="loc_casi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityinstrumentsOtherThanOptionsOutstandingNumber_479"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_477" xlink:to="loc_casi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityinstrumentsOtherThanOptionsOutstandingNumber_479" use="optional" order="6"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_480"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_477" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_480" use="optional" order="7"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExerciseInPeriod" xlink:label="loc_casi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExerciseInPeriod_481"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_477" xlink:to="loc_casi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExerciseInPeriod_481" use="optional" order="8"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_482"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_477" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_482" use="optional" order="9"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisable" xlink:label="loc_casi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisable_484"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_477" xlink:to="loc_casi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisable_484" use="optional" order="10"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingNumberWeightedAverageExercisePrice1" xlink:label="loc_casi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingNumberWeightedAverageExercisePrice1_485"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_477" xlink:to="loc_casi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingNumberWeightedAverageExercisePrice1_485" use="optional" order="11"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageExercisePrice" xlink:label="loc_casi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageExercisePrice_486"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_477" xlink:to="loc_casi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageExercisePrice_486" use="optional" order="12"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisePrice" xlink:label="loc_casi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisePrice_487"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_477" xlink:to="loc_casi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisePrice_487" use="optional" order="13"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriodWeightedAverageExercisePrice" xlink:label="loc_casi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriodWeightedAverageExercisePrice_488"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_477" xlink:to="loc_casi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriodWeightedAverageExercisePrice_488" use="optional" order="14"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisableWeightedAverageExercisePrice" xlink:label="loc_casi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisableWeightedAverageExercisePrice_490"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_477" xlink:to="loc_casi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisableWeightedAverageExercisePrice_490" use="optional" order="15"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/StockholdersEquityDetailsTextual">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_358"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_345"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_358" xlink:to="loc_us-gaap_StatementTable_345" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_346"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_345" xlink:to="loc_us-gaap_StatementClassOfStockAxis_346" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_359"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_346" xlink:to="loc_us-gaap_ClassOfStockDomain_359" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_359_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_346" xlink:to="loc_us-gaap_ClassOfStockDomain_359_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_WarrantMember" xlink:label="loc_us-gaap_WarrantMember_366989"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_359" xlink:to="loc_us-gaap_WarrantMember_366989" use="optional" order="5"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsidiarySaleOfStockAxis" xlink:label="loc_us-gaap_SubsidiarySaleOfStockAxis_348"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_345" xlink:to="loc_us-gaap_SubsidiarySaleOfStockAxis_348" use="optional" order="6"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SaleOfStockNameOfTransactionDomain" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_349"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_348" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_349" use="optional" order="7"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SaleOfStockNameOfTransactionDomain" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_349_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_348" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_349_default" use="optional" order="8"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_SecuritiesPurchaseAgreementsMember" xlink:label="loc_casi_SecuritiesPurchaseAgreementsMember_365"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_349" xlink:to="loc_casi_SecuritiesPurchaseAgreementsMember_365" use="optional" order="9"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PrivatePlacementMember" xlink:label="loc_us-gaap_PrivatePlacementMember_366"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_349" xlink:to="loc_us-gaap_PrivatePlacementMember_366" use="optional" order="10"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_SalesAgreementMember" xlink:label="loc_casi_SalesAgreementMember_367023"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_349" xlink:to="loc_casi_SalesAgreementMember_367023" use="optional" order="11"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_350"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_345" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_350" use="optional" order="12"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_351"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_350" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_351" use="optional" order="13"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_351_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_350" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_351_default" use="optional" order="14"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaap_SubsequentEventMember_367"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_351" xlink:to="loc_us-gaap_SubsequentEventMember_367" use="optional" order="15"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_352"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_345" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_352" use="optional" order="16"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaap_RelatedPartyDomain_353"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_352" xlink:to="loc_us-gaap_RelatedPartyDomain_353" use="optional" order="17"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaap_RelatedPartyDomain_353_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_352" xlink:to="loc_us-gaap_RelatedPartyDomain_353_default" use="optional" order="18"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InvestorMember" xlink:label="loc_us-gaap_InvestorMember_368"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_353" xlink:to="loc_us-gaap_InvestorMember_368" use="optional" order="19"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_AgentWarrantsMember" xlink:label="loc_casi_AgentWarrantsMember_369"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_353" xlink:to="loc_casi_AgentWarrantsMember_369" use="optional" order="20"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_HcWainwrightCoLlcMember" xlink:label="loc_casi_HcWainwrightCoLlcMember_370"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_353" xlink:to="loc_casi_HcWainwrightCoLlcMember_370" use="optional" order="21"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementScenarioAxis" xlink:label="loc_us-gaap_StatementScenarioAxis_354"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_345" xlink:to="loc_us-gaap_StatementScenarioAxis_354" use="optional" order="22"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_355"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementScenarioAxis_354" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_355" use="optional" order="23"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_355_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementScenarioAxis_354" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_355_default" use="optional" order="24"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_356"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_345" xlink:to="loc_srt_RangeAxis_356" use="optional" order="25"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_357"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_356" xlink:to="loc_srt_RangeMember_357" use="optional" order="26"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_357_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_356" xlink:to="loc_srt_RangeMember_357_default" use="optional" order="27"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MaximumMember" xlink:label="loc_srt_MaximumMember_372"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_357" xlink:to="loc_srt_MaximumMember_372" use="optional" order="28"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_MeasurementInputTypeAxis" xlink:label="loc_us-gaap_MeasurementInputTypeAxis_365678"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_345" xlink:to="loc_us-gaap_MeasurementInputTypeAxis_365678" use="optional" order="29"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_MeasurementInputTypeDomain" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_365679"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_365678" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_365679" use="optional" order="30"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_MeasurementInputTypeDomain" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_365679_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_365678" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_365679_default" use="optional" order="31"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_MeasurementInputExpectedTermMember" xlink:label="loc_us-gaap_MeasurementInputExpectedTermMember_365680"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_365679" xlink:to="loc_us-gaap_MeasurementInputExpectedTermMember_365680" use="optional" order="32"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_MeasurementInputRiskFreeInterestRateMember" xlink:label="loc_us-gaap_MeasurementInputRiskFreeInterestRateMember_367019"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_365679" xlink:to="loc_us-gaap_MeasurementInputRiskFreeInterestRateMember_367019" use="optional" order="33"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_MeasurementInputPriceVolatilityMember" xlink:label="loc_us-gaap_MeasurementInputPriceVolatilityMember_367020"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_365679" xlink:to="loc_us-gaap_MeasurementInputPriceVolatilityMember_367020" use="optional" order="34"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_StockToBeIssuedShares" xlink:label="loc_casi_StockToBeIssuedShares_373"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_358" xlink:to="loc_casi_StockToBeIssuedShares_373" use="optional" order="35"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1" xlink:label="loc_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_376"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_358" xlink:to="loc_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_376" use="optional" order="36"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_FairValueOfWarrantIssued" xlink:label="loc_casi_FairValueOfWarrantIssued_378"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_358" xlink:to="loc_casi_FairValueOfWarrantIssued_378" use="optional" order="37"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_FairValueAssumptionsFairValue" xlink:label="loc_casi_FairValueAssumptionsFairValue_379"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_358" xlink:to="loc_casi_FairValueAssumptionsFairValue_379" use="optional" order="38"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_FairValueAssumptionsExpectedTerms" xlink:label="loc_casi_FairValueAssumptionsExpectedTerms_380"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_358" xlink:to="loc_casi_FairValueAssumptionsExpectedTerms_380" use="optional" order="39"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_FairValueAssumptionsRiskFreeInterestRates" xlink:label="loc_casi_FairValueAssumptionsRiskFreeInterestRates_381"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_358" xlink:to="loc_casi_FairValueAssumptionsRiskFreeInterestRates_381" use="optional" order="40"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_384"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_358" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_384" use="optional" order="41"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SaleOfStockPricePerShare" xlink:label="loc_us-gaap_SaleOfStockPricePerShare_386"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_358" xlink:to="loc_us-gaap_SaleOfStockPricePerShare_386" use="optional" order="42"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_WarrantsToBeIssued" xlink:label="loc_casi_WarrantsToBeIssued_387"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_358" xlink:to="loc_casi_WarrantsToBeIssued_387" use="optional" order="43"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_NetProceedsFromIssuanceOfCommonStock" xlink:label="loc_casi_NetProceedsFromIssuanceOfCommonStock_388"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_358" xlink:to="loc_casi_NetProceedsFromIssuanceOfCommonStock_388" use="optional" order="44"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_StockAndWarrantsToBeIssuedValue" xlink:label="loc_casi_StockAndWarrantsToBeIssuedValue_391"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_358" xlink:to="loc_casi_StockAndWarrantsToBeIssuedValue_391" use="optional" order="45"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights" xlink:label="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_392"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_358" xlink:to="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_392" use="optional" order="46"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_393"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_358" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_393" use="optional" order="47"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight" xlink:label="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight_395"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_358" xlink:to="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight_395" use="optional" order="48"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_ClassOfWarrantOrRightExpirationDate" xlink:label="loc_casi_ClassOfWarrantOrRightExpirationDate_396"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_358" xlink:to="loc_casi_ClassOfWarrantOrRightExpirationDate_396" use="optional" order="49"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfWarrantOrRighstDateFromWhichWarrantsOrRightsExercisable" xlink:label="loc_us-gaap_ClassOfWarrantOrRighstDateFromWhichWarrantsOrRightsExercisable_397"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_358" xlink:to="loc_us-gaap_ClassOfWarrantOrRighstDateFromWhichWarrantsOrRightsExercisable_397" use="optional" order="50"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueOther" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueOther_398"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_358" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueOther_398" use="optional" order="51"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_AgentWarrantsPercentage" xlink:label="loc_casi_AgentWarrantsPercentage_399"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_358" xlink:to="loc_casi_AgentWarrantsPercentage_399" use="optional" order="52"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_AggregateSalesPrice" xlink:label="loc_casi_AggregateSalesPrice_400"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_358" xlink:to="loc_casi_AggregateSalesPrice_400" use="optional" order="53"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesOther" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesOther_402"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_358" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesOther_402" use="optional" order="54"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_PricePerShareAndWarrant" xlink:label="loc_casi_PricePerShareAndWarrant_404"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_358" xlink:to="loc_casi_PricePerShareAndWarrant_404" use="optional" order="55"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_FairValueAssumptionsExpectedVolatilityRates" xlink:label="loc_casi_FairValueAssumptionsExpectedVolatilityRates_365694"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_358" xlink:to="loc_casi_FairValueAssumptionsExpectedVolatilityRates_365694" use="optional" order="56"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockSharesAuthorized" xlink:label="loc_us-gaap_CommonStockSharesAuthorized_366669"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_358" xlink:to="loc_us-gaap_CommonStockSharesAuthorized_366669" use="optional" order="57"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TreasuryStockShares" xlink:label="loc_us-gaap_TreasuryStockShares_366670"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_358" xlink:to="loc_us-gaap_TreasuryStockShares_366670" use="optional" order="58"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_NumberOfWarrantsToPurchaseCommonStockIssuedDuringThePeriod" xlink:label="loc_casi_NumberOfWarrantsToPurchaseCommonStockIssuedDuringThePeriod_366671"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_358" xlink:to="loc_casi_NumberOfWarrantsToPurchaseCommonStockIssuedDuringThePeriod_366671" use="optional" order="59"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_ProceedsFromIssuanceOfCommonStockAndWarrantsGross" xlink:label="loc_casi_ProceedsFromIssuanceOfCommonStockAndWarrantsGross_366672"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_358" xlink:to="loc_casi_ProceedsFromIssuanceOfCommonStockAndWarrantsGross_366672" use="optional" order="60"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PreferredStockSharesAuthorized" xlink:label="loc_us-gaap_PreferredStockSharesAuthorized_366977"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_358" xlink:to="loc_us-gaap_PreferredStockSharesAuthorized_366977" use="optional" order="61"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_FairValueAssumptionsTerm" xlink:label="loc_casi_FairValueAssumptionsTerm_367003"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_358" xlink:to="loc_casi_FairValueAssumptionsTerm_367003" use="optional" order="62"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_FairValueAssumptionsRate" xlink:label="loc_casi_FairValueAssumptionsRate_367009"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_358" xlink:to="loc_casi_FairValueAssumptionsRate_367009" use="optional" order="63"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_RemainingDollarAmountAvailableUnderSalesAgreement" xlink:label="loc_casi_RemainingDollarAmountAvailableUnderSalesAgreement_367022"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_358" xlink:to="loc_casi_RemainingDollarAmountAvailableUnderSalesAgreement_367022" use="optional" order="64"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/EmployeeRetirementPlanDetailsTextual">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_580"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_578"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_580" xlink:to="loc_us-gaap_StatementTable_578" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_579"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_578" xlink:to="loc_us-gaap_StatementClassOfStockAxis_579" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_581"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_579" xlink:to="loc_us-gaap_ClassOfStockDomain_581" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_581_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_579" xlink:to="loc_us-gaap_ClassOfStockDomain_581_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DefinedBenefitPlanContributionsByEmployer" xlink:label="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_582"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_580" xlink:to="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_582" use="optional" order="5"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/StockBasedCompensationDetails">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_410"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_407"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_410" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_407" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_408"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_407" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_408" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_409"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_408" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_409" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_409_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_408" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_409_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ResearchAndDevelopmentExpenseMember" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseMember_412"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_409" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpenseMember_412" use="optional" order="5"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GeneralAndAdministrativeExpenseMember" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpenseMember_413"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_409" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpenseMember_413" use="optional" order="6"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensation" xlink:label="loc_us-gaap_ShareBasedCompensation_414"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_410" xlink:to="loc_us-gaap_ShareBasedCompensation_414" use="optional" order="7"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/StockBasedCompensationDetails1">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_420"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_418"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_420" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_418" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_419"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_418" xlink:to="loc_us-gaap_StatementClassOfStockAxis_419" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_421"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_419" xlink:to="loc_us-gaap_ClassOfStockDomain_421" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_421_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_419" xlink:to="loc_us-gaap_ClassOfStockDomain_421_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_422"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_420" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_422" use="optional" order="5"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_423"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_420" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_423" use="optional" order="6"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_424"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_420" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_424" use="optional" order="7"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_426"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_420" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_426" use="optional" order="8"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/StockBasedCompensationDetails2">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_433"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_429"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_433" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_429" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_dei_LegalEntityAxis_430"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_429" xlink:to="loc_dei_LegalEntityAxis_430" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_434"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_430" xlink:to="loc_dei_EntityDomain_434" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_434_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_430" xlink:to="loc_dei_EntityDomain_434_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis" xlink:label="loc_us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis_431"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_429" xlink:to="loc_us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis_431" use="optional" order="5"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain" xlink:label="loc_us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain_432"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis_431" xlink:to="loc_us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain_432" use="optional" order="6"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain" xlink:label="loc_us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain_432_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis_431" xlink:to="loc_us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain_432_default" use="optional" order="7"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember_435"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain_432" xlink:to="loc_us-gaap_EmployeeStockOptionMember_435" use="optional" order="8"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_436"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_433" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_436" use="optional" order="9"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_437"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_433" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_437" use="optional" order="10"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_438"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_433" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_438" use="optional" order="11"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod_439"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_433" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod_439" use="optional" order="12"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_440"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_433" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_440" use="optional" order="13"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_442"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_433" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_442" use="optional" order="14"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_443"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_433" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_443" use="optional" order="15"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_444"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_433" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_444" use="optional" order="16"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_445"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_433" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_445" use="optional" order="17"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice_446"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_433" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice_446" use="optional" order="18"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_447"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_433" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_447" use="optional" order="19"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_449"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_433" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_449" use="optional" order="20"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_450"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_433" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_450" use="optional" order="21"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_451"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_433" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_451" use="optional" order="22"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_452"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_433" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_452" use="optional" order="23"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_453"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_433" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_453" use="optional" order="24"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_366796"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_433" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_366796" use="optional" order="25"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/StockBasedCompensationDetails3">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_459"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_456"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_459" xlink:to="loc_us-gaap_StatementTable_456" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_457"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_456" xlink:to="loc_us-gaap_StatementClassOfStockAxis_457" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_458"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_457" xlink:to="loc_us-gaap_ClassOfStockDomain_458" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_458_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_457" xlink:to="loc_us-gaap_ClassOfStockDomain_458_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_RangeOneMember" xlink:label="loc_casi_RangeOneMember_460"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_458" xlink:to="loc_casi_RangeOneMember_460" use="optional" order="5"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_RangeTwoMember" xlink:label="loc_casi_RangeTwoMember_461"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_458" xlink:to="loc_casi_RangeTwoMember_461" use="optional" order="6"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_RangeThreeMember" xlink:label="loc_casi_RangeThreeMember_462"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_458" xlink:to="loc_casi_RangeThreeMember_462" use="optional" order="7"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_RangeFourMember" xlink:label="loc_casi_RangeFourMember_463"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_458" xlink:to="loc_casi_RangeFourMember_463" use="optional" order="8"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_RangeFiveMember" xlink:label="loc_casi_RangeFiveMember_464"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_458" xlink:to="loc_casi_RangeFiveMember_464" use="optional" order="9"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit_465"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_459" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit_465" use="optional" order="10"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit_466"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_459" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit_466" use="optional" order="11"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions_467"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_459" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions_467" use="optional" order="12"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2" xlink:label="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2_468"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_459" xlink:to="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2_468" use="optional" order="13"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1" xlink:label="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1_469"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_459" xlink:to="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1_469" use="optional" order="14"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions_470"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_459" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions_470" use="optional" order="15"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1" xlink:label="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1_471"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_459" xlink:to="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1_471" use="optional" order="16"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/StockBasedCompensationDetailsTextual">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_505"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_493"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_505" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_493" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanNameAxis" xlink:label="loc_us-gaap_PlanNameAxis_494"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_493" xlink:to="loc_us-gaap_PlanNameAxis_494" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain_495"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_494" xlink:to="loc_us-gaap_PlanNameDomain_495" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain_495_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_494" xlink:to="loc_us-gaap_PlanNameDomain_495_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_LongTermIncentivePlan2011Member" xlink:label="loc_casi_LongTermIncentivePlan2011Member_506"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_495" xlink:to="loc_casi_LongTermIncentivePlan2011Member_506" use="optional" order="5"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_496"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_493" xlink:to="loc_srt_RangeAxis_496" use="optional" order="6"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_497"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_496" xlink:to="loc_srt_RangeMember_497" use="optional" order="7"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_497_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_496" xlink:to="loc_srt_RangeMember_497_default" use="optional" order="8"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MaximumMember" xlink:label="loc_srt_MaximumMember_507"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_497" xlink:to="loc_srt_MaximumMember_507" use="optional" order="9"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MinimumMember" xlink:label="loc_srt_MinimumMember_508"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_497" xlink:to="loc_srt_MinimumMember_508" use="optional" order="10"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TitleOfIndividualAxis" xlink:label="loc_us-gaap_TitleOfIndividualAxis_498"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_493" xlink:to="loc_us-gaap_TitleOfIndividualAxis_498" use="optional" order="11"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_499"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TitleOfIndividualAxis_498" xlink:to="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_499" use="optional" order="12"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_499_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TitleOfIndividualAxis_498" xlink:to="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_499_default" use="optional" order="13"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_ExecutiveChairmanMember" xlink:label="loc_casi_ExecutiveChairmanMember_510"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_499" xlink:to="loc_casi_ExecutiveChairmanMember_510" use="optional" order="14"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_500"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_493" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_500" use="optional" order="15"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_511"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_500" xlink:to="loc_us-gaap_EquityComponentDomain_511" use="optional" order="16"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_511_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_500" xlink:to="loc_us-gaap_EquityComponentDomain_511_default" use="optional" order="17"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_501"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_493" xlink:to="loc_us-gaap_AwardTypeAxis_501" use="optional" order="18"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_502"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_501" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_502" use="optional" order="19"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_502_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_501" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_502_default" use="optional" order="20"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_PerformanceBasedOptionMember" xlink:label="loc_casi_PerformanceBasedOptionMember_513"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_502" xlink:to="loc_casi_PerformanceBasedOptionMember_513" use="optional" order="21"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_503"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_493" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_503" use="optional" order="22"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_504"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_503" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_504" use="optional" order="23"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_504_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_503" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_504_default" use="optional" order="24"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_515"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_505" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_515" use="optional" order="25"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_516"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_505" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_516" use="optional" order="26"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensation" xlink:label="loc_us-gaap_ShareBasedCompensation_517"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_505" xlink:to="loc_us-gaap_ShareBasedCompensation_517" use="optional" order="27"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_UnrecognizedShareBasedCompensationCostExpectedToBeRecognizedOverWeightedAveragePeriod" xlink:label="loc_casi_UnrecognizedShareBasedCompensationCostExpectedToBeRecognizedOverWeightedAveragePeriod_525"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_505" xlink:to="loc_casi_UnrecognizedShareBasedCompensationCostExpectedToBeRecognizedOverWeightedAveragePeriod_525" use="optional" order="28"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_UnrecognisedShareBasedCompensationCostExpectedToBeRecognizedOverWeightedAveragePeriod" xlink:label="loc_casi_UnrecognisedShareBasedCompensationCostExpectedToBeRecognizedOverWeightedAveragePeriod_526"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_505" xlink:to="loc_casi_UnrecognisedShareBasedCompensationCostExpectedToBeRecognizedOverWeightedAveragePeriod_526" use="optional" order="29"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantedExpireTerms" xlink:label="loc_casi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantedExpireTerms_527"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_505" xlink:to="loc_casi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantedExpireTerms_527" use="optional" order="30"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber_528"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_505" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber_528" use="optional" order="31"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_ShareBasedPaymentCashReceivedFromStockOptionExercises" xlink:label="loc_casi_ShareBasedPaymentCashReceivedFromStockOptionExercises_372429"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_505" xlink:to="loc_casi_ShareBasedPaymentCashReceivedFromStockOptionExercises_372429" use="optional" order="32"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_PerformanceShareBasedCompensationExpense" xlink:label="loc_casi_PerformanceShareBasedCompensationExpense_372437"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_505" xlink:to="loc_casi_PerformanceShareBasedCompensationExpense_372437" use="optional" order="33"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/IncomeTaxesDetails">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_259"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_256"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_259" xlink:to="loc_us-gaap_StatementTable_256" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_257"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_256" xlink:to="loc_us-gaap_StatementClassOfStockAxis_257" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_260"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_257" xlink:to="loc_us-gaap_ClassOfStockDomain_260" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_260_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_257" xlink:to="loc_us-gaap_ClassOfStockDomain_260_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementScenarioAxis" xlink:label="loc_us-gaap_StatementScenarioAxis_258"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_256" xlink:to="loc_us-gaap_StatementScenarioAxis_258" use="optional" order="5"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_261"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementScenarioAxis_258" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_261" use="optional" order="6"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_261_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementScenarioAxis_258" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_261_default" use="optional" order="7"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic_262"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_259" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic_262" use="optional" order="8"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign_263"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_259" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign_263" use="optional" order="9"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_264"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_259" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_264" use="optional" order="10"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/IncomeTaxesDetails1">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_269"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_267"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_269" xlink:to="loc_us-gaap_StatementTable_267" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_268"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_267" xlink:to="loc_us-gaap_StatementClassOfStockAxis_268" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_271"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_268" xlink:to="loc_us-gaap_ClassOfStockDomain_271" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_271_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_268" xlink:to="loc_us-gaap_ClassOfStockDomain_271_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredTaxAssetsLiabilitiesNetAbstract" xlink:label="loc_us-gaap_DeferredTaxAssetsLiabilitiesNetAbstract_270"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_269" xlink:to="loc_us-gaap_DeferredTaxAssetsLiabilitiesNetAbstract_270" use="optional" order="5"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwards" xlink:label="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards_272"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxAssetsLiabilitiesNetAbstract_270" xlink:to="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards_272" use="optional" order="6"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsResearch" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsResearch_273"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxAssetsLiabilitiesNetAbstract_270" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsResearch_273" use="optional" order="7"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredTaxAssetsGoodwillAndIntangibleAssets" xlink:label="loc_us-gaap_DeferredTaxAssetsGoodwillAndIntangibleAssets_274"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxAssetsLiabilitiesNetAbstract_270" xlink:to="loc_us-gaap_DeferredTaxAssetsGoodwillAndIntangibleAssets_274" use="optional" order="8"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost_275"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxAssetsLiabilitiesNetAbstract_270" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost_275" use="optional" order="9"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredTaxAssetsOther" xlink:label="loc_us-gaap_DeferredTaxAssetsOther_276"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxAssetsLiabilitiesNetAbstract_270" xlink:to="loc_us-gaap_DeferredTaxAssetsOther_276" use="optional" order="10"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredTaxAssetsValuationAllowance" xlink:label="loc_us-gaap_DeferredTaxAssetsValuationAllowance_277"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxAssetsLiabilitiesNetAbstract_270" xlink:to="loc_us-gaap_DeferredTaxAssetsValuationAllowance_277" use="optional" order="11"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredTaxAssetsNet" xlink:label="loc_us-gaap_DeferredTaxAssetsNet_278"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxAssetsLiabilitiesNetAbstract_270" xlink:to="loc_us-gaap_DeferredTaxAssetsNet_278" use="optional" order="12"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/IncomeTaxesDetails2">
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_EffectiveIncomeTaxRateReconciliationLineItemsLineItems" xlink:label="loc_casi_EffectiveIncomeTaxRateReconciliationLineItemsLineItems_283"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_EffectiveIncomeTaxRateReconciliationLineItemsTable" xlink:label="loc_casi_EffectiveIncomeTaxRateReconciliationLineItemsTable_281"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_casi_EffectiveIncomeTaxRateReconciliationLineItemsLineItems_283" xlink:to="loc_casi_EffectiveIncomeTaxRateReconciliationLineItemsTable_281" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_282"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_casi_EffectiveIncomeTaxRateReconciliationLineItemsTable_281" xlink:to="loc_us-gaap_StatementClassOfStockAxis_282" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_284"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_282" xlink:to="loc_us-gaap_ClassOfStockDomain_284" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_284_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_282" xlink:to="loc_us-gaap_ClassOfStockDomain_284_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate" xlink:label="loc_us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate_285"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_casi_EffectiveIncomeTaxRateReconciliationLineItemsLineItems_283" xlink:to="loc_us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate_285" use="optional" order="5"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_EffectiveIncomeTaxRateReconciliationEffectOfTaxLawChangeAmount" xlink:label="loc_casi_EffectiveIncomeTaxRateReconciliationEffectOfTaxLawChangeAmount_286"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_casi_EffectiveIncomeTaxRateReconciliationLineItemsLineItems_283" xlink:to="loc_casi_EffectiveIncomeTaxRateReconciliationEffectOfTaxLawChangeAmount_286" use="optional" order="6"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes" xlink:label="loc_us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes_287"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_casi_EffectiveIncomeTaxRateReconciliationLineItemsLineItems_283" xlink:to="loc_us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes_287" use="optional" order="7"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxReconciliationTaxCreditsResearch" xlink:label="loc_us-gaap_IncomeTaxReconciliationTaxCreditsResearch_288"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_casi_EffectiveIncomeTaxRateReconciliationLineItemsLineItems_283" xlink:to="loc_us-gaap_IncomeTaxReconciliationTaxCreditsResearch_288" use="optional" order="8"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_IncomeTaxReconciliationTaxCreditsExpirations" xlink:label="loc_casi_IncomeTaxReconciliationTaxCreditsExpirations_289"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_casi_EffectiveIncomeTaxRateReconciliationLineItemsLineItems_283" xlink:to="loc_casi_IncomeTaxReconciliationTaxCreditsExpirations_289" use="optional" order="9"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxReconciliationNondeductibleExpense" xlink:label="loc_us-gaap_IncomeTaxReconciliationNondeductibleExpense_290"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_casi_EffectiveIncomeTaxRateReconciliationLineItemsLineItems_283" xlink:to="loc_us-gaap_IncomeTaxReconciliationNondeductibleExpense_290" use="optional" order="10"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance" xlink:label="loc_us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance_291"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_casi_EffectiveIncomeTaxRateReconciliationLineItemsLineItems_283" xlink:to="loc_us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance_291" use="optional" order="11"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxReconciliationOtherAdjustments" xlink:label="loc_us-gaap_IncomeTaxReconciliationOtherAdjustments_292"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_casi_EffectiveIncomeTaxRateReconciliationLineItemsLineItems_283" xlink:to="loc_us-gaap_IncomeTaxReconciliationOtherAdjustments_292" use="optional" order="12"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxReconciliationChangeInEnactedTaxRate" xlink:label="loc_us-gaap_IncomeTaxReconciliationChangeInEnactedTaxRate_293"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_casi_EffectiveIncomeTaxRateReconciliationLineItemsLineItems_283" xlink:to="loc_us-gaap_IncomeTaxReconciliationChangeInEnactedTaxRate_293" use="optional" order="13"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_294"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_casi_EffectiveIncomeTaxRateReconciliationLineItemsLineItems_283" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_294" use="optional" order="14"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/IncomeTaxesDetails3">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_299"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_297"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_299" xlink:to="loc_us-gaap_StatementTable_297" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_298"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_297" xlink:to="loc_us-gaap_StatementClassOfStockAxis_298" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_300"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_298" xlink:to="loc_us-gaap_ClassOfStockDomain_300" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_300_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_298" xlink:to="loc_us-gaap_ClassOfStockDomain_300_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_UnrecognizedTaxBenefits" xlink:label="loc_us-gaap_UnrecognizedTaxBenefits_301"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_299" xlink:to="loc_us-gaap_UnrecognizedTaxBenefits_301" use="optional" order="5"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions_302"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_299" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions_302" use="optional" order="6"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions_303"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_299" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions_303" use="optional" order="7"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions_366149"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_299" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions_366149" use="optional" order="8"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/IncomeTaxesDetailsTextual">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxContingencyLineItems" xlink:label="loc_us-gaap_IncomeTaxContingencyLineItems_329"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxContingencyTable" xlink:label="loc_us-gaap_IncomeTaxContingencyTable_321"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_329" xlink:to="loc_us-gaap_IncomeTaxContingencyTable_321" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_322"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeTaxContingencyTable_321" xlink:to="loc_us-gaap_AwardTypeAxis_322" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_330"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_322" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_330" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_330_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_322" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_330_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TaxCreditCarryforwardAxis" xlink:label="loc_us-gaap_TaxCreditCarryforwardAxis_323"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeTaxContingencyTable_321" xlink:to="loc_us-gaap_TaxCreditCarryforwardAxis_323" use="optional" order="5"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TaxCreditCarryforwardNameDomain" xlink:label="loc_us-gaap_TaxCreditCarryforwardNameDomain_324"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TaxCreditCarryforwardAxis_323" xlink:to="loc_us-gaap_TaxCreditCarryforwardNameDomain_324" use="optional" order="6"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TaxCreditCarryforwardNameDomain" xlink:label="loc_us-gaap_TaxCreditCarryforwardNameDomain_324_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TaxCreditCarryforwardAxis_323" xlink:to="loc_us-gaap_TaxCreditCarryforwardNameDomain_324_default" use="optional" order="7"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ResearchMember" xlink:label="loc_us-gaap_ResearchMember_331"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxCreditCarryforwardNameDomain_324" xlink:to="loc_us-gaap_ResearchMember_331" use="optional" order="8"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_StatementGeographicalAxis" xlink:label="loc_srt_StatementGeographicalAxis_325"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeTaxContingencyTable_321" xlink:to="loc_srt_StatementGeographicalAxis_325" use="optional" order="9"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_SegmentGeographicalDomain" xlink:label="loc_srt_SegmentGeographicalDomain_326"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_325" xlink:to="loc_srt_SegmentGeographicalDomain_326" use="optional" order="10"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_SegmentGeographicalDomain" xlink:label="loc_srt_SegmentGeographicalDomain_326_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_325" xlink:to="loc_srt_SegmentGeographicalDomain_326_default" use="optional" order="11"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementScenarioAxis" xlink:label="loc_us-gaap_StatementScenarioAxis_327"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeTaxContingencyTable_321" xlink:to="loc_us-gaap_StatementScenarioAxis_327" use="optional" order="12"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_328"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementScenarioAxis_327" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_328" use="optional" order="13"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_328_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementScenarioAxis_327" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_328_default" use="optional" order="14"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxAuthorityAxis" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_367741"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeTaxContingencyTable_321" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_367741" use="optional" order="15"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_367742"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_367741" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_367742" use="optional" order="16"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_367742_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_367741" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_367742_default" use="optional" order="17"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StateAndLocalJurisdictionMember" xlink:label="loc_us-gaap_StateAndLocalJurisdictionMember_367743"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_367742" xlink:to="loc_us-gaap_StateAndLocalJurisdictionMember_367743" use="optional" order="18"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ForeignCountryMember" xlink:label="loc_us-gaap_ForeignCountryMember_367744"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_367742" xlink:to="loc_us-gaap_ForeignCountryMember_367744" use="optional" order="19"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_UnrecognizedTaxBenefits" xlink:label="loc_us-gaap_UnrecognizedTaxBenefits_335"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_329" xlink:to="loc_us-gaap_UnrecognizedTaxBenefits_335" use="optional" order="20"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLossCarryforwards" xlink:label="loc_us-gaap_OperatingLossCarryforwards_336"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_329" xlink:to="loc_us-gaap_OperatingLossCarryforwards_336" use="optional" order="21"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TaxCreditCarryforwardAmount" xlink:label="loc_us-gaap_TaxCreditCarryforwardAmount_339"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_329" xlink:to="loc_us-gaap_TaxCreditCarryforwardAmount_339" use="optional" order="22"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLossCarryforwardsLimitationsOnUse" xlink:label="loc_us-gaap_OperatingLossCarryforwardsLimitationsOnUse_340"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_329" xlink:to="loc_us-gaap_OperatingLossCarryforwardsLimitationsOnUse_340" use="optional" order="23"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate_341"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_329" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate_341" use="optional" order="24"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_EffectiveIncomeTaxRateReconciliationEffectOfTaxLawChangeAmount" xlink:label="loc_casi_EffectiveIncomeTaxRateReconciliationEffectOfTaxLawChangeAmount_342"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_329" xlink:to="loc_casi_EffectiveIncomeTaxRateReconciliationEffectOfTaxLawChangeAmount_342" use="optional" order="25"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/FairValueMeasurementsDetails">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_366058"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_366055"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_366058" xlink:to="loc_us-gaap_StatementTable_366055" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_366056"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_366055" xlink:to="loc_us-gaap_StatementClassOfStockAxis_366056" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_366057"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_366056" xlink:to="loc_us-gaap_ClassOfStockDomain_366057" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_366057_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_366056" xlink:to="loc_us-gaap_ClassOfStockDomain_366057_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_366061"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_366055" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_366061" use="optional" order="5"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_366062"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_366061" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_366062" use="optional" order="6"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_366062_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_366061" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_366062_default" use="optional" order="7"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_366063"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_366062" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_366063" use="optional" order="8"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_366064"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_366062" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_366064" use="optional" order="9"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_366065"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_366062" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_366065" use="optional" order="10"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue_366059"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_366058" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue_366059" use="optional" order="11"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DerivativeLiabilitiesNoncurrent" xlink:label="loc_us-gaap_DerivativeLiabilitiesNoncurrent_366060"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_366058" xlink:to="loc_us-gaap_DerivativeLiabilitiesNoncurrent_366060" use="optional" order="12"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/FairValueMeasurementsDetails1">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_241"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable_239"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_241" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable_239" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_240"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable_239" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_240" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_242"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_240" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_242" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_242_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_240" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_242_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_243"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_241" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_243" use="optional" order="5"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements_244"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_241" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements_244" use="optional" order="6"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPeriodIncreaseDecrease" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPeriodIncreaseDecrease_245"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_241" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPeriodIncreaseDecrease_245" use="optional" order="7"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/FairValueMeasurementsDetailsTextual">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_251"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_249"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_251" xlink:to="loc_us-gaap_StatementTable_249" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_250"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_249" xlink:to="loc_us-gaap_StatementClassOfStockAxis_250" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_252"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_250" xlink:to="loc_us-gaap_ClassOfStockDomain_252" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_252_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_250" xlink:to="loc_us-gaap_ClassOfStockDomain_252_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_366117"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_249" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_366117" use="optional" order="5"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaap_RelatedPartyDomain_366118"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_366117" xlink:to="loc_us-gaap_RelatedPartyDomain_366118" use="optional" order="6"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaap_RelatedPartyDomain_366118_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_366117" xlink:to="loc_us-gaap_RelatedPartyDomain_366118_default" use="optional" order="7"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_SpectrumMember" xlink:label="loc_casi_SpectrumMember_366119"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_366118" xlink:to="loc_casi_SpectrumMember_366119" use="optional" order="8"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_ContingentRightsDescriptionOfTermsOnExpiry" xlink:label="loc_casi_ContingentRightsDescriptionOfTermsOnExpiry_366077"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_251" xlink:to="loc_casi_ContingentRightsDescriptionOfTermsOnExpiry_366077" use="optional" order="9"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_StockIssuedDuringPeriodSharesExerciseOfContingentPurchaseRight" xlink:label="loc_casi_StockIssuedDuringPeriodSharesExerciseOfContingentPurchaseRight_372377"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_251" xlink:to="loc_casi_StockIssuedDuringPeriodSharesExerciseOfContingentPurchaseRight_372377" use="optional" order="10"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/RelatedPartyTransactionsDetailsTextual">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_186"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_181"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_186" xlink:to="loc_us-gaap_StatementTable_181" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_182"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_181" xlink:to="loc_us-gaap_StatementClassOfStockAxis_182" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_187"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_182" xlink:to="loc_us-gaap_ClassOfStockDomain_187" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_187_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_182" xlink:to="loc_us-gaap_ClassOfStockDomain_187_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_183"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_181" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_183" use="optional" order="5"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaap_RelatedPartyDomain_184"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_183" xlink:to="loc_us-gaap_RelatedPartyDomain_184" use="optional" order="6"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaap_RelatedPartyDomain_184_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_183" xlink:to="loc_us-gaap_RelatedPartyDomain_184_default" use="optional" order="7"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_SpectrumMember" xlink:label="loc_casi_SpectrumMember_188"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_184" xlink:to="loc_casi_SpectrumMember_188" use="optional" order="8"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_EmergingTechnologyPartnersLLCMember" xlink:label="loc_casi_EmergingTechnologyPartnersLLCMember_365925"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_184" xlink:to="loc_casi_EmergingTechnologyPartnersLLCMember_365925" use="optional" order="9"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_185"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_181" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_185" use="optional" order="10"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_189"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_185" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_189" use="optional" order="11"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_189_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_185" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_189_default" use="optional" order="12"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ProductOrServiceAxis" xlink:label="loc_srt_ProductOrServiceAxis_365939"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_181" xlink:to="loc_srt_ProductOrServiceAxis_365939" use="optional" order="13"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ProductsAndServicesDomain" xlink:label="loc_srt_ProductsAndServicesDomain_365941"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_365939" xlink:to="loc_srt_ProductsAndServicesDomain_365941" use="optional" order="14"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ProductsAndServicesDomain" xlink:label="loc_srt_ProductsAndServicesDomain_365941_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_365939" xlink:to="loc_srt_ProductsAndServicesDomain_365941_default" use="optional" order="15"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_EVOMELAMember" xlink:label="loc_casi_EVOMELAMember_365948"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_365941" xlink:to="loc_casi_EVOMELAMember_365948" use="optional" order="16"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_MARQIBOMember" xlink:label="loc_casi_MARQIBOMember_367747"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_365941" xlink:to="loc_casi_MARQIBOMember_367747" use="optional" order="17"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_365950"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_181" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_365950" use="optional" order="18"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_365971"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_365950" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_365971" use="optional" order="19"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_365971_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_365950" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_365971_default" use="optional" order="20"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ResearchAndDevelopmentExpenseMember" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseMember_365972"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_365971" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpenseMember_365972" use="optional" order="21"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GeneralAndAdministrativeExpenseMember" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpenseMember_366002"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_365971" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpenseMember_366002" use="optional" order="22"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BalanceSheetLocationAxis" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_365979"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_181" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_365979" use="optional" order="23"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_365980"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_365979" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_365980" use="optional" order="24"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_365980_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_365979" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_365980_default" use="optional" order="25"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PrepaidExpensesAndOtherCurrentAssetsMember" xlink:label="loc_us-gaap_PrepaidExpensesAndOtherCurrentAssetsMember_365982"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_365980" xlink:to="loc_us-gaap_PrepaidExpensesAndOtherCurrentAssetsMember_365982" use="optional" order="26"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TitleOfIndividualAxis" xlink:label="loc_us-gaap_TitleOfIndividualAxis_365984"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_181" xlink:to="loc_us-gaap_TitleOfIndividualAxis_365984" use="optional" order="27"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_365991"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TitleOfIndividualAxis_365984" xlink:to="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_365991" use="optional" order="28"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_365991_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TitleOfIndividualAxis_365984" xlink:to="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_365991_default" use="optional" order="29"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BoardOfDirectorsChairmanMember" xlink:label="loc_us-gaap_BoardOfDirectorsChairmanMember_365993"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_365991" xlink:to="loc_us-gaap_BoardOfDirectorsChairmanMember_365993" use="optional" order="30"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ChiefExecutiveOfficerMember" xlink:label="loc_us-gaap_ChiefExecutiveOfficerMember_365994"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_365991" xlink:to="loc_us-gaap_ChiefExecutiveOfficerMember_365994" use="optional" order="31"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccountsPayableRelatedPartiesCurrent" xlink:label="loc_us-gaap_AccountsPayableRelatedPartiesCurrent_191"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_186" xlink:to="loc_us-gaap_AccountsPayableRelatedPartiesCurrent_191" use="optional" order="32"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessDevelopment" xlink:label="loc_us-gaap_BusinessDevelopment_365924"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_186" xlink:to="loc_us-gaap_BusinessDevelopment_365924" use="optional" order="33"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PurchaseObligation" xlink:label="loc_us-gaap_PurchaseObligation_365935"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_186" xlink:to="loc_us-gaap_PurchaseObligation_365935" use="optional" order="34"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty" xlink:label="loc_us-gaap_RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty_365974"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_186" xlink:to="loc_us-gaap_RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty_365974" use="optional" order="35"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RelatedPartyTransactionPurchasesFromRelatedParty" xlink:label="loc_us-gaap_RelatedPartyTransactionPurchasesFromRelatedParty_365975"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_186" xlink:to="loc_us-gaap_RelatedPartyTransactionPurchasesFromRelatedParty_365975" use="optional" order="36"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_AdvancePaymentOnContractForPurchase" xlink:label="loc_casi_AdvancePaymentOnContractForPurchase_372386"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_186" xlink:to="loc_casi_AdvancePaymentOnContractForPurchase_372386" use="optional" order="37"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/CommitmentsAndContingenciesDetails">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_533"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_531"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_533" xlink:to="loc_us-gaap_StatementTable_531" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_532"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_531" xlink:to="loc_us-gaap_StatementClassOfStockAxis_532" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_534"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_532" xlink:to="loc_us-gaap_ClassOfStockDomain_534" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_534_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_532" xlink:to="loc_us-gaap_ClassOfStockDomain_534_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableCurrent" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableCurrent_535"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_533" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableCurrent_535" use="optional" order="5"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInTwoYears" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInTwoYears_536"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_533" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInTwoYears_536" use="optional" order="6"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInThreeYears" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInThreeYears_537"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_533" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInThreeYears_537" use="optional" order="7"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInFourYears" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInFourYears_538"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_533" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInFourYears_538" use="optional" order="8"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableThereafter" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableThereafter_540"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_533" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableThereafter_540" use="optional" order="9"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsReceivable" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivable_541"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_533" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivable_541" use="optional" order="10"/>
</definitionLink>
<definitionLink xlink:type="extended" xlink:role="http://www.entremed.com/role/CommitmentsAndContingenciesDetailsTextual">
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_549"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_544"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_549" xlink:to="loc_us-gaap_StatementTable_544" xbrldt:contextElement="segment" xbrldt:closed="true" use="optional" order="1"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_545"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_544" xlink:to="loc_us-gaap_StatementClassOfStockAxis_545" use="optional" order="2"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_546"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_545" xlink:to="loc_us-gaap_ClassOfStockDomain_546" use="optional" order="3"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_546_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_545" xlink:to="loc_us-gaap_ClassOfStockDomain_546_default" use="optional" order="4"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_PhaseOneMember" xlink:label="loc_casi_PhaseOneMember_550"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_546" xlink:to="loc_casi_PhaseOneMember_550" use="optional" order="5"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_PhaseTwoMember" xlink:label="loc_casi_PhaseTwoMember_551"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_546" xlink:to="loc_casi_PhaseTwoMember_551" use="optional" order="6"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_PhaseThreeMember" xlink:label="loc_casi_PhaseThreeMember_552"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_546" xlink:to="loc_casi_PhaseThreeMember_552" use="optional" order="7"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_547"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_544" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_547" use="optional" order="8"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_548"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_547" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_548" use="optional" order="9"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_548_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_547" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_548_default" use="optional" order="10"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaap_SubsequentEventMember_553"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_548" xlink:to="loc_us-gaap_SubsequentEventMember_553" use="optional" order="11"/>
<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_dei_LegalEntityAxis_365892"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_544" xlink:to="loc_dei_LegalEntityAxis_365892" use="optional" order="12"/>
<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_365893"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_365892" xlink:to="loc_dei_EntityDomain_365893" use="optional" order="13"/>
<loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_365893_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_365892" xlink:to="loc_dei_EntityDomain_365893_default" use="optional" order="14"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_SpectrumMember" xlink:label="loc_casi_SpectrumMember_365896"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_365893" xlink:to="loc_casi_SpectrumMember_365896" use="optional" order="15"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_CASIWuxiMember" xlink:label="loc_casi_CASIWuxiMember_365900"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_365893" xlink:to="loc_casi_CASIWuxiMember_365900" use="optional" order="16"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ProductOrServiceAxis" xlink:label="loc_srt_ProductOrServiceAxis_365897"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_544" xlink:to="loc_srt_ProductOrServiceAxis_365897" use="optional" order="17"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ProductsAndServicesDomain" xlink:label="loc_srt_ProductsAndServicesDomain_365898"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_365897" xlink:to="loc_srt_ProductsAndServicesDomain_365898" use="optional" order="18"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ProductsAndServicesDomain" xlink:label="loc_srt_ProductsAndServicesDomain_365898_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_365897" xlink:to="loc_srt_ProductsAndServicesDomain_365898_default" use="optional" order="19"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_EVOMELAMember" xlink:label="loc_casi_EVOMELAMember_365899"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_365898" xlink:to="loc_casi_EVOMELAMember_365899" use="optional" order="20"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_StatementGeographicalAxis" xlink:label="loc_srt_StatementGeographicalAxis_365902"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_544" xlink:to="loc_srt_StatementGeographicalAxis_365902" use="optional" order="21"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_SegmentGeographicalDomain" xlink:label="loc_srt_SegmentGeographicalDomain_365903"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_365902" xlink:to="loc_srt_SegmentGeographicalDomain_365903" use="optional" order="22"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_SegmentGeographicalDomain" xlink:label="loc_srt_SegmentGeographicalDomain_365903_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_365902" xlink:to="loc_srt_SegmentGeographicalDomain_365903_default" use="optional" order="23"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_RockvilleMDOfficeMember" xlink:label="loc_casi_RockvilleMDOfficeMember_365904"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_365903" xlink:to="loc_casi_RockvilleMDOfficeMember_365904" use="optional" order="24"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BalanceSheetLocationAxis" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_365905"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_544" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_365905" use="optional" order="25"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_365906"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_365905" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_365906" use="optional" order="26"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_365906_default"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_365905" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_365906_default" use="optional" order="27"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PrepaidExpensesAndOtherCurrentAssetsMember" xlink:label="loc_us-gaap_PrepaidExpensesAndOtherCurrentAssetsMember_365907"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_365906" xlink:to="loc_us-gaap_PrepaidExpensesAndOtherCurrentAssetsMember_365907" use="optional" order="28"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_BusinessCombinationConsiderationMilestoneAchievement" xlink:label="loc_casi_BusinessCombinationConsiderationMilestoneAchievement_554"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_549" xlink:to="loc_casi_BusinessCombinationConsiderationMilestoneAchievement_554" use="optional" order="29"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_PurchaseObligationToPurchaseMaterials" xlink:label="loc_casi_PurchaseObligationToPurchaseMaterials_555"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_549" xlink:to="loc_casi_PurchaseObligationToPurchaseMaterials_555" use="optional" order="30"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LeaseAndRentalExpense" xlink:label="loc_us-gaap_LeaseAndRentalExpense_556"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_549" xlink:to="loc_us-gaap_LeaseAndRentalExpense_556" use="optional" order="31"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDue" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDue_365913"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_549" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDue_365913" use="optional" order="32"/>
<loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PurchaseCommitmentRemainingMinimumAmountCommitted" xlink:label="loc_us-gaap_PurchaseCommitmentRemainingMinimumAmountCommitted_367689"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_549" xlink:to="loc_us-gaap_PurchaseCommitmentRemainingMinimumAmountCommitted_367689" use="optional" order="33"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_AdvancePaymentOnContractForPurchase" xlink:label="loc_casi_AdvancePaymentOnContractForPurchase_372385"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_549" xlink:to="loc_casi_AdvancePaymentOnContractForPurchase_372385" use="optional" order="34"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_InitialCashInvestment" xlink:label="loc_casi_InitialCashInvestment_373097"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_549" xlink:to="loc_casi_InitialCashInvestment_373097" use="optional" order="35"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_TotalFutureInvestment" xlink:label="loc_casi_TotalFutureInvestment_373098"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_549" xlink:to="loc_casi_TotalFutureInvestment_373098" use="optional" order="36"/>
<loc xlink:type="locator" xlink:href="casi-20181231.xsd#casi_PropertiesSubjectToGroundLeases" xlink:label="loc_casi_PropertiesSubjectToGroundLeases_373224"/>
<definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_549" xlink:to="loc_casi_PropertiesSubjectToGroundLeases_373224" use="optional" order="37"/>
</definitionLink>
</linkbase>


5 Subsequent Filings that Reference this Filing

  As Of               Filer                 Filing    For·On·As Docs:Size             Issuer                      Filing Agent

 3/28/24  CASI Pharmaceuticals, Inc.        20-F       12/31/23  142:21M                                    Toppan Merrill Bridge/FA
 4/26/23  CASI Pharmaceuticals, Inc.        20-F       12/31/22  129:16M                                    Toppan Merrill Bridge/FA
 4/26/23  CASI Pharmaceuticals, Inc. (DE)   20-F       12/31/22  129:16M                                    Toppan Merrill Bridge/FA
 3/28/22  CASI Pharmaceuticals, Inc. (DE)   10-K       12/31/21  104:11M                                    Toppan Merrill Bridge/FA
 3/30/21  CASI Pharmaceuticals, Inc. (DE)   10-K       12/31/20  109:13M                                    Toppan Merrill Bridge/FA
Top
Filing Submission 0001144204-19-016832   –   Alternative Formats (Word / Rich Text, HTML, Plain Text, et al.)

Copyright © 2024 Fran Finnegan & Company LLC – All Rights Reserved.
AboutPrivacyRedactionsHelp — Tue., May 14, 12:43:43.2am ET