RELEASE
      AGREEMENT

     

    I
      understand that my employment with Sunesis Pharmaceuticals, Inc. (the
“Company”)
      is
      terminating effective August 4, 2008. I further understand that between now
      and
      that date, I shall receive full pay and benefits from the Company pursuant
      to
      the Notice of Termination I received from the Company on June 3,
      2008.

     

    I
      further
      understand that if I sign this Release Agreement (the “Release”)
      and
      allow it to become effective, then the Company shall provide me with the
      following severance benefits under the terms of my Amended and Restated
      Executive Severance Benefits Agreement dated as of May 28, 2008: (1) a lump-sum
      payment equal to six (6) months’
      of my base salary, less standard payroll deductions and withholdings, payable
      within thirty (30) days after the Effective Date of this Release; (2) provided
      I
      timely elect continued coverage under COBRA (as defined in my
      Amended and Restated Executive Severance Benefits Agreement),
      payment
      of the premiums to continue my group health insurance coverage, including
      coverage for my eligible dependents, for a maximum period of six (6) months
      following my termination (or such lesser number of months as my dependents
      and I
      are eligible for such coverage); and (3) the vesting of my outstanding Stock
      Awards (as defined in my Amended and Restated
      Executive Severance Benefits Agreement)
      shall be
      accelerated such that as of my termination date, those Stock Awards that would
      have vested in the ordinary course over the twelve (12) month period following
      the date of my termination had I remained continuously employed by the Company
      during such period shall be fully vested and exercisable.

     

    I
      further
      understand that if I sign this Release and allow it to become effective, then
      the Company shall provide me with the following additional severance benefits:
      (1) six (6) months of outplacement assistance through Lee Hecht Harrison, under
      the terms of the Company’s contract with Lee Hecht Harrison; and (2) a bonus
      payment equal to 12.5% of my annual base salary, less standard payroll
      deductions and withholdings, payable in a lump-sum within thirty (30) days
      after
      the Effective Date of this Release.

     

    I
      understand that this Release, together with the Amended and Restated Executive
      Severance Benefits Agreement between me and the Company, constitutes the
      complete, final and exclusive embodiment of the entire agreement between me
      and
      the Company with regard to the subject matter hereof. I am not relying on any
      promise or representation by the Company that is not expressly stated therein.
      Certain
      capitalized terms used in this Release are defined in my Amended and Restated
      Executive Severance Benefits Agreement, which I have executed and of which
      this
      Release is a part.

     

    1.
       Proprietary
      Information Obligations. I
      hereby
      confirm my obligations under my Nondisclosure Agreement with the Company dated
      as of December 8, 1999 and my Confidential Information and Invention Assignment
      Agreement with the Company dated as of February 14, 2000.

     

    
      
        
        

      

      
        1.

        
          

        

      

      
        
        

      

    

    2. General
      Release.
      In
      exchange for severance benefits and other consideration provided to me hereunder
      and under the Amended and Restated Executive Severance Benefits Agreement that
      I
      am not
      otherwise entitled to receive, I hereby generally and completely release the
      Company and its current and former directors, officers, employees, stockholders,
      shareholders, partners, agents, attorneys, predecessors, successors, parent
      and
      subsidiary entities, insurers, affiliates, and assigns (collectively, the
“Released
      Parties”)
      from
      any and all claims, liabilities and obligations, both known and unknown, that
      arise out of or are in any way related to events, acts, conduct, or omissions
      occurring prior to my signing this Release (collectively, the “Released
      Claims”).
      The
      Released Claims include, but are not limited to: (1) all claims arising out
      of
      or in any way related to my employment with the Company or its affiliates,
      or
      the termination of that employment; (2) all claims related to my compensation
      or
      benefits, including salary, bonuses, commissions, vacation pay, expense
      reimbursements, severance pay, fringe benefits, stock, stock options, or any
      other ownership interests in the Company or its affiliates; (3) all claims
      for
      breach of contract, wrongful termination, and breach of the implied covenant
      of
      good faith and fair dealing; (4) all tort claims, including claims for fraud,
      defamation, emotional distress, and discharge in violation of public policy;
      and
      (5) all federal, state, and local statutory claims, including claims for
      discrimination, harassment, retaliation, attorneys’ fees, or other claims
      arising under the federal Civil Rights Act of 1964 (as amended), the federal
      Americans with Disabilities Act of 1990, the federal Age Discrimination in
      Employment Act of 1967 (as amended) (“ADEA”),
      the
      federal Employee Retirement Income Security Act of 1974 (as amended), and the
      California Fair Employment and Housing Act (as amended). Notwithstanding the
      foregoing, the following are not included in the Released Claims (the
“Excluded
      Claims”):
      (1)
      any rights or claims for indemnification I may have pursuant to any written
      indemnification agreement with the Company to which I am a party, the charter,
      bylaws, or operating agreements of the Company, or under applicable law; or
      (2)
      any rights which are not waiveable as a matter of law. In addition, nothing
      in
      this Release prevents me from filing, cooperating with, or participating in
      any
      proceeding before the Equal Employment Opportunity Commission, the Department
      of
      Labor, or the California Department of Fair Employment and Housing, except
      that
      I hereby waive my right to any monetary benefits in connection with any such
      claim, charge or proceeding. I hereby represent and warrant that, other than
      the
      Excluded Claims, I am not aware of any claims I have or might have against
      any
      of the Released Parties that are not included in the Released
      Claims.

     

    3. ADEA
      Waiver.
      I
      acknowledge that I am knowingly and voluntarily waiving and releasing any rights
      I may have under the ADEA. I also acknowledge that the consideration given
      for
      the Released Claims is in addition to anything of value to which I was already
      entitled. I further acknowledge that I have been advised by this writing, as
      required by the ADEA, that: (a) the Released Claims do not apply to any rights
      or claims that arise after the date I sign this Release; (b) I should consult
      with an attorney prior to signing this Release (although I may choose
      voluntarily not to do so); (c) I have at least forty-five (45) days to consider
      this Release (although I may choose to voluntarily sign it sooner); (d) I have
      seven (7) days following the date I sign this Release to revoke the Release
      by
      providing written notice to an officer of the Company; and (e) the Release
      will
      not be effective until the date upon which the revocation period has expired
      unexercised, which will be the eighth day after I sign this Release
      (“Effective
      Date”).
      I
      have received with this Release all of the information required by the ADEA,
      including without limitation a detailed list of the job titles and ages of
      all
      employees who were terminated in this group termination and the ages of all
      employees of the Company in the same job classification or organizational unit
      who were not terminated, along with information on the eligibility factors
      used
      to select employees for the group termination and any time limits applicable
      to
      this group termination program.

     

    
      
        
        

      

      
        2.

        
          

        

      

      
        
        

      

    

    4. Section
      1542 Waiver. I
      acknowledge that I have read and understand Section 1542 of the California
      Civil
      Code which reads as follows: “A
      general release does not extend to claims which the creditor does not know
      or
      suspect to exist in his or her favor at the time of executing the release,
      which
      if known by him or her must have materially affected his or her settlement
      with
      the debtor.”
      I hereby
      expressly waive and relinquish all rights and benefits under that section and
      any law of any jurisdiction of similar effect with respect to my release of
      any
      claims I may have against the Company.

     

    5. Representations.
      I hereby
      represent that I have been paid all compensation owed and for all hours worked,
      I have received all the leave and leave benefits and protections for which
      I am
      eligible, and I have not suffered any on-the-job injury for which I have not
      already filed a workers’ compensation claim.

     

    6. Non-Disparagement.
      I hereby
      agree not to disparage the Company, or its officers, directors, employees,
      shareholders or agents, in any manner likely to be harmful to its or their
      business, business reputation, or personal reputation; provided,
      however,
      that I
      will respond accurately and fully to any question, inquiry or request for
      information when required by legal process.

     

    I
      acknowledge that to become effective, I must sign and return this Release to
      the
      Company on or after my termination date of August 4, 2008 (or such earlier
      date
      as I cease to be employed by the Company), and I must not revoke it
      thereafter.

     

    Robert
      S. McDowell, Ph.D.

    /s/
      Robert McDowell

     

    Date:
      August 4, 2008

     

     

    
      
        
        

      

      
        3.