<?xml version="1.0" encoding="US-ASCII"?>
<!-- Generated by Broadridge Transform (tm) - http://www.broadridge.com -->
<!-- Created: Wed Apr 29 12:08:29 UTC 2026 -->
<linkbase xmlns="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 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="https://xbrl.sec.gov/ecd/2025/ecd-2025.xsd#IndividualsOnly" roleURI="http://xbrl.sec.gov/ecd/role/IndividualsOnly"/>
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default"/>
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain"/>
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension"/>
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member"/>
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" arcroleURI="http://xbrl.org/int/dim/arcrole/all"/>
  <definitionLink xlink:role="http://xbrl.sec.gov/ecd/role/IndividualsOnly" xlink:type="extended">
    <loc xlink:type="locator" xlink:label="ecd_AllIndividualsMember" xlink:href="https://xbrl.sec.gov/ecd/2025/ecd-2025.xsd#ecd_AllIndividualsMember"/>
    <loc xlink:type="locator" xlink:label="cmpx_ThomasSchuetzMember" xlink:href="cmpx-20260610.xsd#cmpx_ThomasSchuetzMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ecd_AllIndividualsMember" xlink:to="cmpx_ThomasSchuetzMember" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="cmpx_VeredBiskerLeibMember" xlink:href="cmpx-20260610.xsd#cmpx_VeredBiskerLeibMember"/>
<!-- [WMV7][yzAMNaDaBq8K1dw57nAIVAwOUwEoVGTt7vQvhMZBIqIuwaS1VgvMvlLFCDH902Vn9yuKxd1mzRHKykoQQG+cuTqERSxMq779gNqTegx/hSLwwN/rRZpC4fCKXKVefInSnBIEKDEVP57TyX8ZMFa0Pkh2L1VGdHrpz5fa/ipgtd7Pb200UU81ywjs512Z3PgHTLC3/BG93PMw5EQ06p5FpAiJ10qlr3LZZDvqR8WuM2WQ54vCTBGWmTDNEcnoQBuhTE2TVmL4owdFZr3ZUmwMz0jf3xk3GK/udQBFvIGpB5yUPVZkdL0hZl3HF3ouMGWQCJYMCyTa9l4ueQswdkqNxFZVlfbSlF0qptggcqgUMiWZHoS76vQkDqdiYrIG1pYr1Ix5] CSR-->
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ecd_AllIndividualsMember" xlink:to="cmpx_VeredBiskerLeibMember" order="4" xbrldt:closed="true"/>
  </definitionLink>
</linkbase>
