EXECUTION COPY

               AGREEMENT TO TERMINATE THE COLLABORATION AGREEMENT

         This AGREEMENT TO TERMINATION THE COLLABORATION AGREEMENT (this
"Agreement"), effective December 31, 1999 (the "Effective Date") is made by and
among ABGENIX, INC., a Delaware corporation ("ABX") and JT AMERICA Inc., a New
York corporation ("JTA") and XENOTECH L.P., a California limited partnership
("XT"), with reference to the following facts and circumstances. ABX, JTA and XT
may be referred to herein each individually as a "Party" and jointly as the
"Parties."

                                    RECITALS

         A. WHEREAS, Cell Genesys, Inc. ("CGI"), the predecessor company of ABX,
and JT Immunotech USA, Inc. ("Immunotech"), a wholly-owned subsidiary of JTA
(which is itself a wholly-owned subsidiary of Japan Tobacco Inc. ("JTI")),
formed XT in 1991 to develop genetically modified strains of mice which can
produce fully human monoclonal antibodies ("XenoMouse Animals"), and to
commercialize products generated therefrom;

         B. WHEREAS, CGI, Immunotech and XT entered into that certain
Collaboration Agreement effective June 12, 1991, as amended (the "Collaboration
Agreement"), pursuant to which those parties conducted a sponsored research
project for the development of transgenic animals capable of producing human
monoclonal antibodies;

         C. WHEREAS, CGI, Immunotech and XT entered into that certain Field
License effective June 12, 1991, as amended (the "Prior Field License") to
govern those parties' rights with respect to the use of technology created
pursuant to or practiced in the context of the Collaboration Agreement ("Project
Technology") in the Field (as defined below);

         D. WHEREAS, CGI, Immunotech and XT entered into that certain Expanded
Field License effective June 12, 1991, as amended (the "Expanded Field License")
to govern those parties' rights with respect to the use of Project Technology in
the Expanded Field (as defined in the Expanded Field License);

         E. WHEREAS, CGI assigned to ABX (its wholly-owned subsidiary at such
time), its interest in XT and in the Collaboration Agreement, the Prior Field
License and the Expanded Field License and in 1997, Immunotech merged into JTA
and its interest in XT and in the Collaboration Agreement, the Prior Field
License and the Expanded Field License was assigned to JTA by operation of law;

         F. WHEREAS, XT, JTA and ABX have amended and restated the terms of the
Prior Field License pursuant to the terms of that certain Amended and Restated
Field License entered into between XT, JTA and ABX of even date herewith (the
"Amended and Restated Field License") and have further amended the Expanded
Field License pursuant to that certain Amendment to the Expanded Field License
of even date therewith;

         G. WHEREAS, the Parties desire to terminate the Collaboration Agreement
pursuant to the terms and conditions set forth in this Agreement;


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         NOW THEREFORE, for and in consideration of the covenants, conditions,
and undertakings hereinafter set forth, the Parties agree as follows:

1.       DEFINITIONS

         For purposes of this Agreement, capitalized terms set forth in this
Agreement and not otherwise defined herein shall have the meaning set forth in
the Amended and Restated Field License.

         1.1 "OPTION AGREEMENT" means that certain Multi-Antigen Research
License and Option Agreement by and between JTI and ABX effective December 31,
1999.

2.       EARLY TERMINATION OF THE COLLABORATION AGREEMENT

         2.1 The Parties hereby agree to terminate the Collaboration Agreement
effective as of the Effective Date. Notwithstanding Section 10.6(b) of the
Collaboration Agreement, only the following Sections and Articles shall survive
such termination: Sections 6.1, 6.2 (solely with respect to patent applications
that have been filed prior to the Effective Date), 6.3 (solely with respect to
patents for which a Party has exercised its rights with respect to abandoned
patent applications or patents during the term of the Collaboration Agreement),
6.4, 10.6(a), 10.7, 11.3 (as to activities conducted during the term of the
Collaboration Agreement), 11.4, 11.7, 11.8, and 11.10, 11.11 and 11.13. Except
as expressly provided in this Section 2.1, no other provisions of the
Collaboration Agreement shall survive termination thereof; except that the
confidentiality obligations of Article 8 shall be superseded by and survive as
provided in Article 6 of the Option Agreement.

3.       INDEMNIFICATION

         3.1 BY JTA. Subject to ABX's compliance with Section 3.3, JTA agrees to
indemnify, defend and hold ABX and its Affiliates and their directors, officers,
employees, and agents harmless from and against any losses, claims, damages,
liabilities, or actions resulting directly from any Third Party claims
(collectively, "Liabilities") arising from the breach of any representations,
warranties, covenants or other obligations of JTA under this Agreement, except
to the extent that such Liabilities arise from ABX's breach of any of its
representations, warranties, covenants or other obligations under this
Agreement.

         3.2 BY ABX. Subject to JTA's compliance with Section 3.3, ABX agrees to
indemnify, defend and hold JTA and its Affiliates and their directors, officers,
employees, and agents harmless from and against any Liabilities arising from the
breach of any representations, warranties, covenants or other obligations of ABX
under this Agreement, except to the extent that such Liabilities arise from
JTA's breach of any of its representations, warranties, covenants or other
obligations under this Agreement.

         3.3 INDEMNIFICATION PROCEDURES. If a Party (the "Indemnitee") intends
to claim indemnification under this Article 3, it shall promptly notify the
indemnifying Party (the "Indemnitor") in writing of any Liability in respect of
which the Indemnitee or its directors,


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officers, employees or agents intend to claim such indemnification, and the
Indemnitor shall have the right to participate in, and, to the extent the
Indemnitor so desires, to assume the defense thereof with counsel mutually
satisfactory to the Parties. The indemnity obligation of this Article 3 shall
not apply to amounts paid in settlement of any loss, claim, damage, liability
or action if such settlement is effected without the consent of the
Indemnitor, which consent shall not be withheld or delayed unreasonably. The
failure to deliver written notice to the Indemnitor within a reasonable time
after the commencement of any such action shall not relieve such Indemnitor
of any liability to the Indemnitee under this Article 3, except to the extent
that such failure is prejudicial to its ability to defend such action. The
Party claiming indemnification under this Article 3 and its directors,
officers, employees and agents, shall cooperate fully with the Indemnitor and
its legal representatives in the investigation of any action, claim or
liability covered by this Article 3.

4.       REPRESENTATIONS, WARRANTIES AND COVENANTS

         4.1 REPRESENTATIONS AND WARRANTIES OF ABX. ABX represents and warrants
to JTA that (i) it has the full right and authority to enter into this
Agreement; (ii) it has taken all necessary action on its part to authorize the
execution and delivery of this Agreement and the performance of its obligations
hereunder; (iii) to the knowledge of ABX as of the Effective Date, there are no
existing or threatened actions, suits or claims pending with respect to the
subject matter hereof or the right of ABX to enter into and perform its
obligations under this Agreement; and (iv) it has not entered and during the
term of this Agreement will not enter any other agreement inconsistent or in
conflict with this Agreement.

         4.2 REPRESENTATIONS AND WARRANTIES OF JTA. JTA represents and warrants
to ABX that (i) it has the full right and authority to enter into this
Agreement; (ii) it has taken all necessary action on its part to authorize the
execution and delivery of this Agreement and the performance of its obligations
hereunder; (iii) to the knowledge of JTA as of the Effective Date, there are no
existing or threatened actions, suits or claims pending with respect to the
subject matter hereof or the right of JTA to enter into and perform its
obligations under this Agreement; and (iv) it has not entered and during the
term of this Agreement will not enter any other agreement inconsistent or in
conflict with this Agreement.

5.       MISCELLANEOUS PROVISIONS

         5.1 GOVERNING LAWS. This Agreement shall be interpreted and construed
in accordance with the laws of the State of California, USA, without regard to
conflict of laws principles.

         5.2 WAIVER. It is agreed that no waiver by a Party hereto of any breach
or default of any of the covenants or agreements herein set forth shall be
deemed a waiver as to any subsequent and/or similar breach or default.

         5.3 ASSIGNMENT. Neither this Agreement nor any right or obligation
hereunder may be assigned or delegated, in whole or part, by a Party without the
prior written consent of the


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other Parties; provided that such written consent shall not be required
where: (i) either Party assigns this Agreement to any entity that acquires
substantially all of the assets to which this Agreement relates, (ii) JTA
assigns this Agreement to a Majority-Owned Affiliate of JTI or (iii) ABX
assigns this Agreement to an Affiliate. The terms and conditions of this
Agreement shall be binding on and inure to the benefit of the permitted
successors and assigns of the Parties. Any assignment not in conformance with
this Section 5.3 shall be null, void and of no legal effect. For
clarification this Agreement shall survive any dissolution of XT.

         5.4 INDEPENDENT CONTRACTORS. The relationship of the Parties is that of
independent contractors. The Parties shall not be deemed to be agents, partners
or joint venturers of the others for any purpose as a result of this Agreement
or the transactions contemplated thereby.

         5.5 COMPLIANCE WITH LAWS. In exercising their rights under this
Agreement, the Parties shall fully comply with the requirements of any and all
applicable laws, regulations, rules and orders of any governmental body having
jurisdiction over the exercise of rights under this Agreement.

         5.6 FURTHER ACTIONS. Each Party agrees to execute, acknowledge and
deliver such further instruments and to do all such other acts as may be
necessary or appropriate in order to carry out the purposes and intent of this
Agreement.

         5.7 NOTICES. Any notice, request, approval or consent required or
permitted to be given between the Parties hereto shall be given in writing, and
shall be deemed to have been properly given if delivered in person, transmitted
by telecopy (with machine confirmation of transmission and confirmation by
personal delivery, first class certified mail or courier), or mailed by first
class certified mail to the other Party at the appropriate address set forth
below, or to such other address as may be designated in writing by a Party from
time to time in accordance with this Agreement.

         JT America Inc.:                   JT America Inc.
                                            375 Park Avenue, Suite #1307
                                            New York, NY 10152
                                            Fax: (212) 319-8993
                                            Attn: President

         With copies to:                    Gilbert, Segall and Young LLP
                                            430 Park Avenue
                                            New York, NY  10022
                                            Fax:  (212) 644-4051
                                            Attn:  Neal N. Beaton, Esq.


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                                            Japan Tobacco Inc.
                                            JT Building
                                            2-1 Toranoman 2-chome
                                            Minato-Ku, Tokyo 105
                                            Japan
                                            Fax: 011-81-3-5-479-0321
                                            Attn:   Vice President,
                                                    Pharmaceutical Division

                                            Akros Pharma Inc.
                                            1400 Fashion Island Blvd.
                                            Suite 910
                                            San Mateo, CA  94404
                                            Fax:  (650) 312-8028
                                            Attn:  President

         Abgenix, Inc. or
         Xenotech L.P.                      Abgenix, Inc.
                                            7601 Dumbarton Circle
                                            Fremont, CA  94555
                                            Fax:  (510) 608-6511
                                            Attn:  President

         With a copy to:                    Cooley Godward LLP
                                            3000 El Camino Real
                                            Five Palo Alto Square
                                            Palo Alto, CA  94306-2155
                                            Fax:  (650) 857-0663
                                            Attn:  Robert L. Jones, Esq.

         5.8 SEVERABILITY. In the event that any provision of this Agreement
becomes or is declared by a court of competent jurisdiction to be illegal,
unenforceable or void, this Agreement shall continue in full force and effect
without said provision and the parties shall discuss in good faith appropriate
revised arrangements.

         5.9 FORCE MAJEURE. Nonperformance of any Party shall be excused to the
extent that performance is rendered impossible by strike, fire, earthquake,
flood, governmental acts or orders or restrictions, failure of suppliers, or any
other reason where failure to perform is beyond the reasonable control, and not
caused by the negligence, intentional conduct or misconduct of the
non-performing Party.

         5.10 NO CONSEQUENTIAL DAMAGES. IN NO EVENT SHALL ANY PARTY HERETO BE
LIABLE FOR SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THIS
AGREEMENT OR THE EXERCISE OF ITS RIGHTS HEREUNDER.

         5.11 DISPUTE RESOLUTION; ARBITRATION. The Parties will attempt to
resolve any dispute under this Agreement by mutual agreement, and, if required,
there shall be a face-to-face meeting between the Chief Executive Officer of ABX
and the President of JTA. Any dispute under this Agreement which is not settled
after such meeting shall be finally settled by binding arbitration,


                                       5.



conducted in accordance with the Commercial Arbitration Rules of the American
Arbitration Association by three (3) arbitrators appointed in accordance with
said rules. The arbitration proceedings and all pleadings and written
evidence shall be in the English language. Any written evidence originally in
a language other than English shall be submitted in English translation
accompanied by the original or a true copy thereof. The costs of the
arbitration, including administrative and arbitrators' fees, shall be shared
equally by the parties to the arbitration. Each Party shall bear its own
costs and attorneys' and witness' fees; PROVIDED THAT the prevailing party in
any arbitration, as determined by the arbitration panel, shall be entitled to
an award against the other party in the amount of the prevailing party's
costs and reasonable attorneys' fees. A disputed performance or suspended
performances pending the resolution of the arbitration must be completed
within thirty (30) days following the final decision of the arbitrators. Any
arbitration subject to this Section 5.11 shall be completed within six (6)
months from the filing of notice of a request for such arbitration.

         5.12 COMPLETE AGREEMENT. It is understood and agreed between ABX and
JTA that this Agreement, the Amended and Restated Field License and the Expanded
Field License, as amended on June 28, 1996 and on the Effective Date, constitute
the entire agreement, both written and oral, between the Parties with respect to
the subject matter hereof, and supersede and cancel all prior agreements
respecting the subject matter hereof, either written or oral, expressed or
implied. No amendment or change hereof or addition hereto shall be effective or
binding on either of the Parties unless reduced to writing and executed by the
respective duly authorized representatives of ABX and JTA.

         5.13 COUNTERPARTS. This Agreement may be executed in counterparts, each
of which shall be deemed to be an original and both together shall be deemed to
be one and the same agreement.

         5.14 HEADINGS. The captions to the several Articles and Sections hereof
are not a part of this Agreement, but are included merely for convenience of
reference only and shall not affect its meaning or interpretation.


                                       6.



         IN WITNESS WHEREOF, the Parties have caused this Agreement to be
executed by their respective duly authorized officers as of the day and year
first above written.


         ABGENIX, INC.                                XENOTECH, INC. AS GENERAL
                                                      PARTNER OF XENOTECH, L.P.

         By: /s/ R. Scott Greer                       By: /s/ Raymond M. Withy
            -------------------------------------        -----------------------
            R. Scott Greer                               Raymond M. Withy
            President and Chief Executive Officer        Chairman

         JT AMERICA INC.

         By: /s/ Shuji Kondo
            -------------------------------------
            Shuji Kondo
            President


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