<PAGE>
                                                                    Exhibit 10.2

                                            ***TEXT OMITTED AND FILED SEPARATELY
                                                CONFIDENTIAL TREATMENT REQUESTED


                             COLLABORATION AGREEMENT

                                     Effective:  July 9, 2001 ("Effective Date")

      EPIMMUNE INC., having a principal place of business at 5820 Nancy Ridge
Drive, San Diego, CA 92121 ("EPMN"), and GENENCOR INTERNATIONAL, INC., having a
principal place of business at 925 Page Mill Road, Palo Alto, CA 94304-1013
("GCOR") (collectively referred to herein as the "Parties") agree as follows:

      WHEREAS, the Parties have entered into that certain License Agreement of
even date herewith (the "License Agreement") and that certain Securities
Purchase Agreement of even date herewith; and

      WHEREAS, the Parties have entered into that certain Interim Research
Agreement effective April 2, 2001 (the "Interim Research Agreement"), and in
connection with the License Agreement the Parties wish to extend the research
and development as initiated in said Interim Research Agreement on the terms and
conditions set forth herein;

      NOW THEREFORE, the Parties agree as follows:

                                    ARTICLE I
                                   DEFINITIONS

1.1 "Biological Material" shall mean materials such as epitopes, constructs,
    expression systems, vectors, DNA or protein, polypeptides, cells, strains,
    mice and the like.

1.2 "Invention" shall mean any invention or discovery, patentable or otherwise,
    which arises out of the Program, and which is first conceived and/or reduced
    to practice during the Collaboration Term.

1.3 "Program" shall mean the research and development activities relating to the
    development of Licensed Products conducted by EPMN and GCOR under this
    Agreement during the Collaboration Term. The Program will be conducted
    pursuant to the Work Plan.

1.4 "Project" shall mean the specific projects for each Virus within the overall
    Program.

1.5 "Project Leader" shall mean the person appointed by EPMN ("EPMN Project
    Leader") and GCOR ("GCOR Project Leader") and approved by the Steering
    Committee to lead the technical efforts for a specified Project.

1.6 "Steering Committee" shall have the meaning set forth in Section 3.1.


                                       1.
<PAGE>
1.7 "Work Plan" shall mean the detailed plan relating to the conduct of the
    Program developed and agreed to in writing by the Parties, as may be amended
    by written agreement of the Parties. The Work Plan will include such detail
    as the objectives of the Program, the research and development plan,
    staffing, timelines, deliverables of the Program and the like. The Work Plan
    is set forth on Exhibit A attached hereto and incorporated herein.

All other capitalized terms shall have the meaning set forth in the License
Agreement.

                                   ARTICLE II


                    RESEARCH AND DEVELOPMENT COLLABORATION

2.1 Scope of the Collaboration. The Parties hereby undertake to jointly carry
    out the Program in accordance with the Work Plan attached as Exhibit A
    hereto with the purpose of developing Licensed Products for use and sale
    within the Licensed Field. The Parties from time to time as recommended by
    the Steering Committee may adjust the Work Plan by mutual written agreement.

2.2 Interim Research Agreement. Upon the Effective Date of this Agreement, the
    Interim Research Agreement shall terminate and the Interim Project (as
    defined in the Interim Research Agreement) will be incorporated into the
    Program as reflected in the Work Plan.

2.3 Performance. Payment of the funding by GCOR in accordance with Sections 4.1
    and 4.2 shall be a condition to EPMN's obligation to perform the work set
    out in the Work Plan, and shall be a basis for termination of this Agreement
    by EPMN under Section 8.2 if such payments are not timely made. Adequate and
    appropriate staffing by EPMN in accordance with Section 4.3 shall be a
    condition to GCOR's obligation to make payments pursuant to Section 4.2, and
    shall be a basis for termination of the Agreement by GCOR under Section 8.2
    if such staffing is not adequately provided. Performance of the work to be
    conducted by EPMN in accordance with Section 2.4 and timely delivery of the
    deliverables set forth for EPMN in the Work Plan and Section 2.5 hereof,
    shall be a condition to GCOR's obligation to make payments pursuant to
    Section 4.2, and shall be a basis for termination of this Agreement by GCOR
    under Section 8.2.

2.4 Performance Obligations. The Collaboration shall be conducted at and/or
    coordinated from the facilities of each Party under the direction and
    supervision of the Steering Committee. Each Party shall use commercially
    reasonable efforts to diligently carry out and perform its tasks and duties
    under the Program within the time periods set out in the Work Plan. As used
    herein "commercially reasonable efforts" means, unless the Parties agree
    otherwise, those efforts consistent with the exercise of prudent scientific,
    clinical and business judgment, as applied to other products of similar
    scientific and commercial potential. Each Party shall be responsible for the
    administrative management and, subject to the funding


                                       2.
<PAGE>
    obligations of GCOR under Section 4.1, fiscal control and all other expenses
    incurred by it for tasks and duties assigned to it in the Program. Prior to
    any extraordinary expense to be incurred by EPMN, the Steering Committee
    shall review the nature and necessity of such extraordinary expense and may
    make a recommendation to GCOR for its payment of such extraordinary expense.

2.5 Deliverables. EPMN will use commercially reasonable efforts to deliver to
    GCOR the deliverables to be provided to GCOR in accordance with the Work
    Plan. GCOR will use commercially reasonable efforts to deliver to EPMN the
    deliverables to be provided to EPMN in accordance with the Work Plan

2.6 Interim Reports. The Project Leaders and such members of the Project teams
    as deemed appropriate shall have teleconference calls at least once every
    two weeks. The EPMN Project Leader will provide a bi-monthly report of
    progress towards goals of the applicable Project to the GCOR Project Leader,
    with a copy to the Steering Committee, due promptly after the end of the
    relevant two-month reporting period. Periodically and at least quarterly,
    the Project Leaders shall report progress on their Project to the Steering
    Committee.

2.7 Final Report. Promptly after the expiration or termination of the
    Collaboration Term, EPMN will provide GCOR a final written report detailing
    all information, data and results arising from the Program (the "Final
    Report"). GCOR shall own the Final Report and notwithstanding Article VII
    hereof shall have the right to use and disclose the contents of the Final
    Report for any purpose.

2.8 Disclaimer. NEITHER PARTY GUARANTEES THE OUTCOME OF ANY WORK PERFORMED
    PURSUANT TO THIS AGREEMENT. EXCEPT AS EXPRESSLY SET FORTH IN THIS AGREEMENT,
    THE LICENSE AGREEMENT AND THE SECURITIES PURCHASE AGREEMENT, NEITHER PARTY
    MAKES ANY REPRESENTATION OR WARRANTY TO THE OTHER PARTY OF ANY NATURE,
    EXPRESS OR IMPLIED, INCLUDING, WITHOUT LIMITATION, ANY WARRANTY OF
    NONINFRINGMENT, MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

                                   ARTICLE III
                               STEERING COMMITTEE

3.1 Membership. A committee (the "Steering Committee") consisting of three (3)
    members appointed by EPMN and three (3) members appointed by GCOR shall be
    established in order to monitor and coordinate the joint collaboration
    efforts under this Agreement including the Program. The Steering Committee
    members of a Party shall collectively have one (1) vote total on any matter
    within the scope of the Program coming before the Steering Committee. The
    Steering Committee may invite additional non-voting representatives from
    both Parties to participate in meetings as deemed necessary and appropriate.


                                       3.
<PAGE>
3.2 Responsibilities. The Steering Committee shall have general responsibility,
    subject to the provisions of Section 3.4 below, for directing the research
    and development efforts under the Program and for monitoring the work done
    under the Program. The Steering Committee shall in good faith discuss
    matters related, but not limited, to:

                  -     Goals of the Collaboration;
                  -     Setting of priorities and time frames for the
                        performance of certain activities and deliverables
                        outlined in the Work Plan;
                  -     Possible changes to, expansion of or abandonment of the
                        Work Plan;
                  -     Possible conflicts of interest;
                  -     Inclusion of any third parties or any intellectual
                        property rights or know-how belonging to third parties
                        in a Project;
                  -     Review any proposed extraordinary expenses by EPMN
                        relating to or necessitated by its performance under the
                        Work Plan and make a recommendation to GCOR regarding
                        payment of such extraordinary expenses;
                  -     Determine achievement of R&D-based milestones;
                  -     Personnel requirements for each goal or Project within
                        the Program; and
                  -     Funding requirements for each goal or Project within the
                        Program subject to the funding obligations set forth in
                        this Agreement.

3.3 Meetings. The Steering Committee shall hold meetings at such times and
    places as shall be determined by a majority of the entire membership of the
    Steering Committee, provided that in no event shall such meetings be held
    less frequently than once every quarter. Such meetings may be held in person
    or by telephone conference, provided that any decision made during a
    telephone conference is evidenced by a confirmed writing signed by one or
    more of the members of the Steering Committee from each Party. The Steering
    Committee shall keep minutes of each of its meeting, which shall include a
    description of all actions approved and any action items to be addressed.

3.4 Votes. Actions to be taken by the Steering Committee pursuant to the terms
    of this Agreement shall only be taken following the unanimous vote of the
    Steering Committee. The Steering Committee shall attempt to have all
    decisions approved by all members of the Steering Committee. If the Steering
    Committee is unable to reach a unanimous decision, such matters shall be
    referred to the management of each Party for consideration and action. While
    the Steering Committee may take actions to coordinate the efforts taken by
    each Party under the Program and to make recommendations concerning the
    matters set forth in Section 3.2, the Steering Committee shall not have any
    authority to enter into any contract or to amend the terms and condition of
    this Agreement or the License Agreement or incur any liability on behalf of
    either Party but shall be required to refer any such matters to, and obtain
    authorization from, the respective management of each Party.


                                       4.
<PAGE>
    Notwithstanding the creation of the Steering Committee, each Party shall
    retain the rights, powers and discretion granted to it under this Agreement
    and such Steering Committee shall not be delegated with any such rights,
    powers or discretion unless the Parties expressly agree in writing.

3.5 Expenses. Each Party shall bear all expenses of its representatives related
    to the Steering Committee and the attendance at any meetings of the Steering
    Committee.

                                   ARTICLE IV
                                     FUNDING

4.1 Funding. Subject to the terms and conditions set forth herein, during the
    Collaboration Term GCOR shall fund annually up to [...***...] EPMN full time
    equivalents (FTE) at [...***...] for the work performed under the Work Plan.
    This payment is based on the [...***...] expended by EPMN in support of the
    Program.

4.2 R&D Expense Payments. GCOR agrees to make [...***...] to EPMN within
    [...***...] of the date GCOR receives the last of EPMN's [...***...]
    expended on behalf of the Program during the previous [...***...]. Promptly
    (and in any event within [...***...]) after the Effective Date hereof and
    receipt of EPMN's [...***...] expended on the Interim Research Project, GCOR
    will pay EPMN the balance due for the work performed on the Interim Research
    Project.

4.3 Staffing. Staffing levels will be mutually agreed to by the Parties in
    writing through the operation of the Steering Committee and based on the
    needs of the Program. The overall levels of personnel allocated to the
    Program will be reviewed and adjusted quarterly by the Steering Committee to
    reflect the needs of the Program. There will be a designated Project Leader
    from each Party for each Project within the Program. The EPMN Project Leader
    for each Project may not be changed without the prior consent of GCOR, which
    will not unreasonably be withheld. The Steering Committee will review
    quarterly the EPMN personnel working on the Program.

4.4 GCOR Costs. GCOR will pay [...***...] for work on the Program, [...***...].

4.5 Late Payments. In the event that any payment due hereunder is not made when
    due, the payment shall accrue interest from the date due at the rate of
    [...***...]; provided, however, that in no event shall such rate exceed the
    maximum legal annual interest rate. The payment of such interest shall not
    limit a Party from exercising any other rights it may have as a consequence
    of the lateness of any payment.


                                               *CONFIDENTIAL TREATMENT REQUESTED
                                       5.
<PAGE>
                                    ARTICLE V
                              R&D-BASED MILESTONES

5.1 R&D-Based Milestones. Upon determination by the Steering Committee, based on
    its review of the scientific data and results of the Program, that a
    particular milestone was achieved, GCOR will make certain non-refundable,
    lump sum payments to EPMN ("R&D Milestone Payments"). The technical
    criteria, timelines or other factors affecting payment and the relevant
    payment amounts are provided in Table I.

5.2 Timing of Payment. Promptly, and no later than [...***...] after the
    Steering Committee determines that a milestone has been met, GCOR shall pay
    EPMN the applicable R&D Milestone Payment.

                                     TABLE I

<TABLE>
<CAPTION>
        ----------------------------------------------------------------
        Technical Target for   Time of achievement   Amount of Milestone
        each Project           of Target             Payment to EPMN
        ----------------------------------------------------------------
<S>                            <C>                   <C>
        HBV Project
        EpiGene II HBV         [...***...]           [...***...]
        validated for
        immunogenicity
        ----------------------------------------------------------------
        HPV Project
        EpiGene CTL Cassette   [...***...]           [...***...]
        for HPV
        16/18/45/31/33/58/52

        ----------------------------------------------------------------
        HCV Project
        EpiGene CTL Cassette   [...***...]           [...***...]
        of HCV conserved
        sequences validated
        for immunogenicity

        ----------------------------------------------------------------
</TABLE>

*       "Work Plan Date" shall mean the date for achievement of the applicable
milestone as set forth in the Work Plan as of the Effective Date.

                                   ARTICLE VI
                 OWNERSHIP OF RESULTS AND INTELLECTUAL PROPERTY

6.1 EPMN Technology. EPMN Technology shall continue to be owned or Controlled by
    EPMN, subject to the licenses granted to GCOR pursuant to the License
    Agreement.


                                               *CONFIDENTIAL TREATMENT REQUESTED
                                       6.
<PAGE>
6.2 Inventions and Patent Rights. The inventing Party shall own Inventions and
    Patent Rights relating thereto. Subject to the licenses granted to GCOR and
    EPMN pursuant to the License Agreement, EPMN shall own all Sole
    Collaboration Patent Rights and EPMN and GCOR shall jointly own all Joint
    Collaboration Patent Rights. Inventorship shall be determined in accordance
    with US Patent Law. Any disputes regarding inventorship shall be brought to
    the Steering Committee, who acting on advice of counsel will try to resolve
    such disputes in a manner consistent with maintaining the validity of the
    Patent Right. Each Party shall promptly notify the other Party of any
    Inventions made pursuant to this Agreement, such notice to include a copy of
    an invention report or disclosure form.

6.3 Preparation and Prosecution of Sole Collaboration Patent Rights. After
    notice to GCOR, EPMN shall be entitled to apply for patent protection in its
    own name and at its own expense for any Sole Collaboration Patent Rights.
    EPMN shall routinely and at least [...***...] provide GCOR (throuGH the
    Steering Committee) with information on the status of said Sole
    Collaboration Patent Rights including reports on the filing, prosecution and
    issuance of such. EPMN will provide GCOR an opportunity to discuss and will
    consider in good faith GCOR's suggestions regarding major prosecution events
    with respect to the Sole Collaboration Patent Rights. Such major prosecution
    events shall include substantive amendments to claims, response to final
    rejections and notices of allowance, filing decisions in the US as well as
    foreign patent offices, oppositions, revocations, re-examination or other
    substantive prosecution matters with respect to the Sole Collaboration
    Patent Rights. In the event that EPMN desires to abandon any patent
    application or patent included within the Sole Collaboration Patent Rights,
    EPMN shall provide reasonable prior written notice to GCOR of such intention
    to abandon, and at GCOR's request assign or otherwise transfer to GCOR all
    of EPMN's right, title and interest in and to the Sole Collaboration Patent
    Rights designated in such notice and shall execute all documents necessary
    to effect such assignment or transfer.

6.4 Preparation and Prosecution of Joint Collaboration Patent Rights. EPMN and
    GCOR shall jointly agree to apply for patent protection in their joint names
    for any Joint Collaboration Patent Rights. In the event the Parties agree to
    file Joint Collaboration Patent Rights, the Parties will agree which Party
    is in a better position to prepare, file and prosecute such Patent Rights.
    In absence of an agreement, an independent attorney, mutually agreeable to
    the Parties, will file Joint Collaboration Patent Rights. GCOR will bear the
    external expense for preparing, filing and prosecuting the Joint
    Collaboration Patent Rights. In the event that one Party desires to abandon
    any patent application or patent included within the Joint Collaboration
    Patent Rights (including any election by GCOR to discontinue payment of
    expenses with respect to any patent application or patent included within
    the Joint Collaboration Patent Rights), such Party shall provide reasonable
    prior written notice to the other Party of such intention to abandon, and at
    the request of the other Party, assign or otherwise transfer to such other
    Party all of such Party's right, title and interest in and to the Joint
    Collaboration Patent Rights


                                               *CONFIDENTIAL TREATMENT REQUESTED
                                       7.
<PAGE>
    designated in such notice and shall execute all documents necessary to
    effect such assignment or transfer.

6.5 Patent Enforcement. In the event of third party infringement of
    Collaboration Patent Rights, the Parties shall comply with the terms of
    Section 8.2 in the License Agreement.

                                   ARTICLE VII
                                 CONFIDENTIALITY

7.1 Confidentiality. Sections 11.1 and 11.2 of the License Agreement shall
    control the disclosure of any Confidential Information made by either Party
    hereunder.

7.2 Biological Material. Any Biological Material made available to a party
    ("Receiving Party") by the other party ("Delivering Party") is made
    available for research purposes within the Program only and shall not be
    used for any other purpose without the prior written consent of the
    Delivering Party. Biological Material provided hereunder will not be used
    for experiments in which human beings are subjected to the Biological
    Material, nor for research purposes other than the Program, for third
    parties, nor will Biological Material be transferred to any party outside
    the Receiving Party without the prior written consent of the Delivering
    Party. The Receiving Party obtains no rights or license in the transferred
    Biological Material nor may the Receiving Party file any patent applications
    claiming such Biological Material without the Delivering Party's prior
    consent. The Receiving Party will handle such Biological Material in
    compliance with all laws, regulations and guidelines applicable to the
    Biological Material and its use. The Biological Material is experimental in
    nature, and is provided AS IS without any warranties with respect to
    performance or fitness for particular purpose, or to completeness and
    accuracy of information accompanying the Biological Material. The Receiving
    Party acknowledges that the Biological Material is provided AS IS and
    without any representation or warranty, express or implied unless otherwise
    agreed by the Parties.

                                  ARTICLE VIII
                              TERM AND TERMINATION

8.1 Term. This Agreement, unless terminated sooner as provided elsewhere herein,
    shall expire on September 1, 2003, which term can be extended by mutual
    agreement of the Parties.

8.2 Termination Due to Material Breach. If a Party to this Agreement commits a
    material breach of any provision of this Agreement (including but not
    limited to Articles II, IV, VI and VII) and fails to remedy such breach
    within [...***...] with respect to the breach of any payment obligation)
    after written notice thereof from the other Party stating the intent to
    terminate, the Party not in default may, at its option, terminate this
    Agreement by giving written notice to the Party in default.


                                               *CONFIDENTIAL TREATMENT REQUESTED
                                       8.
<PAGE>
8.3 Termination Due to Termination of the License Agreement. If a Party to this
    Agreement terminates the License Agreement as a result of the other Party's
    commission of a material breach thereof and failure to cure same within the
    applicable terms of the License Agreement, the Party so terminating the
    License Agreement shall be permitted to terminate this Agreement.

8.4 Effect of Termination by GCOR. In the event of termination by GCOR pursuant
    to Sections 8.2 or 8.3, GCOR shall pay to EPMN all payments for [...***...]
    actually expended by EPMN as of the effective date of terminatION but shall
    have no further obligation to make payment for work that was not performed
    as of the effective date of termination. GCOR may at its discretion and
    cost, ask EPMN to continue to work on the Program for no more than
    [...***...] in order to wind down all research and development efforts. Upon
    such termination, EPMN shall promptly provide the Final Report of Section
    2.7 to GCOR. In the event of such termination, the provisions of Section
    10.5.3 of the License Agreement shall apply.

8.5 Effect of Termination by EPMN. In the event of termination by EPMN pursuant
    to Section 8.2 or 8.3, GCOR shall pay to EPMN all payments for [...***...]
    actually expended by EPMN as of the effective date of termination. In the
    event of such termination, the provisions of Section 10.5.1 of the License
    Agreement shall apply.

8.6 Survival. Expiration or termination of this Agreement shall not terminate
    any obligation of either Party to the other Party, including any payment
    obligation, that has accrued prior to the date of expiration or termination.
    The provisions contained in Sections 2.7, 6.1, 6.2, 8.4, 8.5, 8.6 and 8.7
    and Articles VII and IX of this Agreement shall survive its expiration or
    earlier termination.

8.7 Remedies. In the event of any breach of any provision of this Agreement, in
    addition to the termination rights set forth herein, each Party shall have
    all other rights and remedies at law or equity to enforce this Agreement.

                                   ARTICLE IX
                                  MISCELLANEOUS

9.1 Force Majeure. Each of the Parties hereto shall be excused from the
    performance of its obligations hereunder (other than payment obligations)
    and shall not be liable for damages to the other in the event that such
    performance is prevented by circumstances beyond its effective control. Such
    excuse from performance shall continue for as long as the condition
    responsible for such excuse continues and for a period of thirty (30) days
    thereafter, provided that if such excuse continues for a period of one
    hundred and eighty (180) days, the Party whose performance is not being
    prevented shall be entitled to terminate this Agreement. For the purpose of
    this Agreement circumstances beyond the effective control of the Party which
    excuse said Party from performance shall include, without limitation, acts
    of God, enactments, regulations or laws of any government, injunctions or
    judgment of any court, war, civil commotion, destruction of facility or
    materials by fire, earthquake,


                                               *CONFIDENTIAL TREATMENT REQUESTED
                                       9.
<PAGE>
    Tsunami, storm or other casualty, plague of epic proportions, famine, labor
    disturbances and failure of public utilities or common carrier.

9.2 Independent Contractors. Nothing in this Agreement is intended or shall be
    deemed to constitute a partnership, agency, employment or joint venture
    relationship between the Parties. All activities by the Parties hereunder
    shall be performed by the Parties as independent parties. Neither Party
    shall incur any debts or make any commitment for or on behalf of the other
    Party except to the extent, if at all, specifically provided herein or
    subsequently agreed upon.

9.3 Assignment. This Agreement shall not be assignable by either Party without
    the prior written consent of the other Party, such consent not to be
    unreasonably withheld or delayed, except a Party may make such an assignment
    without the other Party's consent to Affiliates or to a successor to
    substantially all of the business assets relating to the Licensed Field of
    such Party, whether by merger, sale of stock, sale or transfer of assets or
    other transaction; provided, however, that in the event of such transaction,
    no intellectual property rights of any Affiliate or third party that is an
    acquiring party shall be included in the technology licensed hereunder. This
    Agreement shall be binding upon and inure to the benefit of the Parties'
    successors, legal representatives and assigns.

9.4 Amendments of Agreement. This Agreement may be amended or modified or one or
    more provisions hereof waived only by a written instrument signed by both
    Parties.

9.5 Severability. In the event that any one or more of the provisions of this
    Agreement should for any reason be held by any court or authority having
    jurisdiction over this Agreement and the Parties to be invalid, illegal or
    unenforceable, such provisions shall be deleted in such jurisdiction;
    elsewhere this Agreement shall not be affected.

9.6 Article Headings. The section headings contained in this Agreement are for
    convenience only and are to be of no force or effect in construing and
    interpreting this Agreement.

9.7 Notices. Any notice, report, request, approval, payment, consent or other
    communication required or permitted to be given under this Agreement shall
    be in writing and shall for all purposes be deemed to be fully given and
    received, if delivered in person or sent by registered mail, postage prepaid
    or by facsimile transmission to the respective parties at the following
    addresses:

                  If to EPMN:       EPIMMUNE INC.
                                    5820 Nancy Ridge Drive
                                    San Diego, CA  92121
                                    Attention:  Chief Executive Officer
                                    Fax No:  858-860-2600


                                      10.
<PAGE>
                  If to GCOR:       GENENCOR INTERNATIONAL, INC.
                                    925 Page Mill Road
                                    Palo Alto, CA  94304
                                    Attention:  General Counsel
                                    Fax No:  650-845-6507

    Either party may change its address for the purpose of this Agreement by
    giving the other Party written notice of its new address.

9.8 Non-Waiver For Failure To Enforce Compliance. The express or implied waiver
    by either Party of a breach of any provision of this Agreement shall not
    constitute a continuing waiver of other breaches of the same or other
    provisions of this Agreement.

9.9 Applicable Law. This Agreement shall be construed and interpreted in
    accordance with the laws of the State of California without regard to
    conflict of law provisions.

9.10 Counterparts. This Agreement may be executed in one or more counterparts,
    each of which is an original but all of which, taken together, shall
    constitute one and the same instrument.

   AS WITNESS the hands of authorized signatories for the Parties on the date
first mentioned above.


EPIMMUNE INC.


By:   /s/ Robert J. De Vaere
     ----------------------------
     Robert J. De Vaere
     Vice President, Finance and
     Chief Financial Officer


GENENCOR INTERNATIONAL, INC.

By:   /s/ Debby Jo Blank
     ----------------------------
          Debby Jo Blank

Title:    CBO
      ---------------------------


                                      11.
<PAGE>
                                   APPENDIX A
                                    WORK PLAN

[...***...]    9 Pages


                                               *CONFIDENTIAL TREATMENT REQUESTED