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                                                                  Exhibit 10.1

                CONFIDENTIAL TREATMENT REQUESTED BY ABGENIX, INC.


                        RESEARCH COLLABORATION AGREEMENT


      THIS RESEARCH COLLABORATION AGREEMENT dated as of July 15, 1998 (this
"Agreement"), is entered into between ABGENIX, INC., a Delaware corporation
("Abgenix"), having a place of business at 7601 Dumbarton Circle, Fremont,
California 94555, and MILLENNIUM BIOTHERAPEUTICS, INC., a Delaware corporation
("MBio"), having a place of business at 620 Memorial Drive, Cambridge,
Massachusetts 02139, with respect to the following facts:

      WHEREAS, Abgenix and MBio are interested in negotiating a research license
and option agreement (the "Research License and Option Agreement") regarding the
generation of human monoclonal antibodies to [***] (the "Antigen") where the
antibodies to the Antigen are generated through the use of certain Abgenix
technology; and

      WHEREAS, in connection with, and during the conduct of, such negotiations,
the parties desire to conduct a research program pursuant to which (a) MBio will
immunize, with the Antigen, certain of Abgenix's transgenic mice which are
capable of producing human antibodies when immunized with antigen (the
"XenoMouse(TM) Animals") provided by Abgenix to MBio and will generate
antibodies therefrom, (b) MBio will conduct certain analyses and
characterizations of such antibodies, and (c) the parties will review and
analyze the data and results of such research activities.

      NOW, THEREFORE, in consideration of the foregoing premises and the mutual
covenants herein contained, the parties hereby agree as follows:

      1. Definitions. For purposes of this Agreement, the terms defined in this
Section 1 shall have the respective meanings set forth below:

           "Abgenix Materials" shall mean, collectively, (a) the XenoMouse
Animals and other materials specified in Exhibit A hereto, as well as any
derivatives, progeny, modifications or improvements thereto developed, created,
synthesized or designed therefrom, and any genetic material

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therefrom; and (b) any XenoMouse Animals immunized with the Antigen; provided,
however, the Abgenix materials shall not include Research Materials and
Inventions.

           "Confidential Information" shall mean, with respect to a party, all
information of any kind whatsoever (including without limitation, compilations,
data, formulae, models, patent disclosures, procedures, processes, projections,
protocols, results of experimentation and testing, specifications, strategies
and techniques), and all tangible and intangible embodiments thereof of any kind
whatsoever (including without limitation, apparatus, biological or chemical
materials, animals, cells, compositions, documents, drawings, machinery, patent
applications, records, reports), which is owned or controlled by such party and
is disclosed by such party to the receiving party and is marked, identified as
or otherwise acknowledged to be confidential at the time of disclosure to the
receiving party. Notwithstanding the foregoing, Confidential Information of a
party shall not include information which the receiving party can establish by
written documentation (a) to have been publicly known prior to disclosure of
such information by the disclosing party to the receiving party, (b) to have
become publicly known, without fault on the part of the receiving party,
subsequent to disclosure of such information by the disclosing party to the
receiving party, (c) to have been received by the receiving party at any time
from a source, other than the disclosing party, rightfully having possession of
and the right to disclose such information free of confidentiality obligations,
(d) to have been otherwise known by the receiving party free of confidentiality
obligations prior to disclosure of such information by the disclosing party to
the receiving party, or (e) to have been independently developed by employees or
agents of the receiving party without access to or use of such information
disclosed by the disclosing party to the receiving party. The parties
acknowledge that the foregoing exceptions shall be narrowly construed and that
the obligations imposed upon each party under Section 6 below shall be relieved
solely with respect to such Confidential Information of the disclosing party
which falls within the above exceptions and not with respect to related
portions, other combinations, or characteristics of the Confidential Information
of the disclosing party including, without limitation, advantages, operability,
specific purposes, uses and the like.

           "Materials" shall mean, collectively, the Abgenix Materials and the
Research Materials and Inventions.



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           "Research" shall mean the interim research program described in
Exhibit B hereto.

           "Research Materials and Inventions" shall mean [***] which results
from the performance of the Research by MBio.

           "Xenotech" shall mean Xenotech L.P., a California limited
partnership.

      2.   Research.

           a. Abgenix shall transfer to MBio the XenoMouse Animals and other
materials specified in Exhibit A hereto for the sole purpose of performing the
Research. MBio shall use the Abgenix Materials for the sole purpose of
performing the Research, at its address listed above, under commercially and
scientifically reasonable containment conditions, and not for any commercial,
business or other use or purpose without the prior express written consent of
Abgenix. MBio shall not transfer or provide access to the Abgenix Materials
transferred to it by Abgenix hereunder to any other person or entity or to any
location other than its address set forth above, without the prior express
written consent of Abgenix (which consent may be conditioned inter alia upon
such person or entity duly executing and delivering Abgenix's standard


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form of material transfer agreement therefor); provided, however, that MBio
shall have the right to transfer the Research Materials and Inventions to
Abgenix. MBio shall limit access to the Abgenix Materials to those of its
employees working on its premises, to the extent such access is reasonably
necessary in connection with its activities as expressly authorized by this
Agreement.

           b. MBio shall conduct the Research under the direct supervision of
[***], who shall be the primary contact for MBio regarding the Research. MBio
shall provide Abgenix with reasonable access to such persons (in person, by
telephone or otherwise as reasonably requested), on reasonable notice and during
normal business hours, to discuss the status of the Research and the results
thereof.

           c. In consideration for Abgenix's resources and efforts expended in
connection with the transfer of the Abgenix Materials, upon execution of this
Agreement, MBio shall pay to Abgenix the sum of [***].

      3. Further Restrictions on Use and Control over the XenoMouse Animals.
Abgenix is willing to transfer the XenoMouse Animals to MBio solely on the terms
and conditions contained in this Agreement. The XenoMouse Animals contain
technology and intellectual property which has been licensed to Abgenix under
specific terms and conditions set forth in certain licensing agreements with
third parties, including without limitation Xenotech. The transfer of the
XenoMouse Animals and the use of XenoMouse Animals by MBio is made expressly
subject to the following terms and conditions:

           a. all XenoMouse Animals transferred to MBio shall be the sole
property of Abgenix, and the transfer of physical possession to MBio, and/or
possession or use by MBio of XenoMouse Animals shall not be, nor be construed
as, a sale, lease, offer to sell or lease, or other transfer of title to or any
interest in any XenoMouse Animals;

           b. all XenoMouse Animals shall remain in the control of MBio, and
MBio shall not (and shall not attempt or purport to) transfer the XenoMouse
Animals to any third party, without the prior express written consent of Abgenix
(which may be conditioned inter alia upon such third party duly


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executing and delivering Abgenix's standard form of material transfer agreement
therefor);

           c. MBio shall not directly or indirectly use or attempt to use the
XenoMouse Animals or any derivatives, information or biological or chemical
materials derived from, based upon or related thereto to reproduce, generate,
create or produce, through breeding, reverse-engineering, genetic manipulation
or otherwise, the XenoMouse Animals or other transgenic mice or other transgenic
animals;

           d. the XenoMouse Animals shall be delivered to MBio solely for the
purpose of immunizing the XenoMouse Animals with the Antigen as specified in
Exhibit B, and MBio shall not use the XenoMouse Animals for any purpose other
than immunizing the XenoMouse Animals with the Antigen and subsequent use of
such immunized XenoMouse Animals as reasonably necessary solely for purposes of
conducting the Research;

           e. MBio shall not (and shall not attempt or purport to) transfer,
assign, sell, have sold, lease, offer to sell or lease, otherwise transfer title
to, or otherwise distribute or license, sublicense or otherwise commercialize or
exploit, any XenoMouse Animals or any interest in any XenoMouse Animals;

           f. MBio shall not directly or indirectly use the XenoMouse Animals to
make or use antibodies to CD4;

           g. Other than Research Materials and Inventions as defined in Section
1 and as provided in Section 7(b) of this Agreement, Abgenix shall own all
right, title and interest in and to all discoveries, inventions, materials,
products, derivatives, know-how and information (whether or not patentable),
together with all patent rights and other intellectual property rights therein,
which are conceived, made, created or developed by MBio (and any of its agents
or employees) through any use of the XenoMouse Animals which is not in
accordance with the terms and conditions set forth in this Agreement; and

           h. Xenotech shall be a third-party beneficiary of the obligations and
commitments by MBio set forth in items (a) through (f) above.



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      4. Reports. MBio shall keep Abgenix informed of all uses made of the
Abgenix Materials provided to it. MBio shall provide Abgenix with reasonable
access to all source data and information resulting from the Research and shall
provide Abgenix with summary written reports of the Research upon reasonable
request by Abgenix.

      5. Publication. Unless otherwise agreed to in writing by Abgenix or
otherwise provided in Section 6 below, neither party shall have the right to
disclose to third parties, or to otherwise publish, the Research Materials and
Inventions, the reports described in Section 4 above (or any data or information
contained therein), or the source data and information described in Section 4
above.

      6.   Confidentiality.

           a. During the term of this Agreement and for a period of five (5)
years following the expiration or earlier termination hereof, each party shall
maintain in confidence the Confidential Information of the other party, and
shall not disclose, use or grant the use of the Confidential Information of the
other party except on a need-to-know basis to such party's directors, officers
and employees, and to such party's consultants working on such party's premises,
to the extent such disclosure is reasonably necessary in connection with such
party's activities as expressly authorized by this Agreement. To the extent that
disclosure to any person is authorized by this Agreement, prior to disclosure, a
party shall obtain written agreement of such person to hold in confidence and
not disclose, use or grant the use of the Confidential Information of the other
party except as expressly permitted under this Agreement. Each party shall
notify the other party promptly upon discovery of any unauthorized use or
disclosure of the other party's Confidential Information. Upon the expiration or
earlier termination of this Agreement, each party shall return to the other
party all tangible items regarding the Confidential Information of the other
party and all copies thereof; provided, however, that each party shall have the
right to retain one (1) copy for its legal files for the sole purpose of
determining its obligations hereunder.

           b. Notwithstanding anything to the contrary in this Agreement, for
purposes of this Agreement, the Abgenix Materials and all oral or written
communications received by


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MBio regarding the Abgenix Materials are, and shall remain, Confidential
Information of Abgenix.

           c. Notwithstanding anything to the contrary in this Agreement, for
purposes of this Agreement, the Research Materials and Inventions and all oral
or written communications received by MBio regarding the Research Materials and
Inventions are, and shall remain, Confidential Information of Abgenix and MBio.

           d. Neither party shall disclose any terms or conditions of this
Agreement to any third party without the prior consent of the other party;
provided, however, that a party may disclose the terms or conditions of this
Agreement, (i) on a need-to-know basis to its affiliated companies including,
but not limited to, for MBio, Millennium Pharmaceuticals, Inc., Millennium
Information, Inc., Millennium Predictive Medicine, Inc., plus any future
affiliated companies that own a majority of the stock of MBio or that MBio owns
a majority of the stock thereof and for Abgenix, Xenotech L.P. plus any future
affiliated companies that own a majority of the stock of Abgenix or that Abgenix
owns a majority of the stock thereof) and to its/their legal and financial
advisors to the extent such disclosure is reasonably necessary in connection
with such party's activities as expressly permitted by this Agreement, (ii) to a
third party in connection with (A) an equity investment in such party by a third
party, (B) a merger, consolidation or similar transaction entered into by such
party, or (C) the sale of all or substantially all of the assets of such party,
and (iii) as may, in the reasonable opinion of such party's counsel, be required
by applicable law, regulation or court order, including without limitation, a
disclosure in connection with such party's filing of a registration statement or
other filing with the United States Securities and Exchange Commission (in which
event such party will first consult with the other party with respect to such
disclosure). Notwithstanding the foregoing, prior to execution of this Agreement
Abgenix and MBio shall agree upon the substance of information that can be used
to describe the terms of this transaction, and each party may disclose such
information, as modified by written agreement of Abgenix and MBio from time to
time, without the consent of the other.

           e. The confidentiality obligations under this Section 6 shall not
apply to the extent that a party is required to disclose Confidential
Information of the other



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party by applicable law, regulation or order of a governmental agency or a court
of competent jurisdiction; provided, however, that such party shall provide
written notice thereof to the other party and sufficient opportunity to object
to any such disclosure or to request confidential treatment thereof.

      7. Ownership and Control of Materials.

           a. All right, title and interest to the Abgenix Materials and all
patent rights and other intellectual property rights therein shall belong solely
to Abgenix. MBio shall not (and shall not attempt or purport to) transfer,
assign, sell, have sold, lease, offer to sell or lease, otherwise transfer title
to, or otherwise distribute or license, sublicense or otherwise commercialize or
exploit, any Abgenix Materials, unless Abgenix otherwise expressly agrees in
writing. Promptly upon the earlier of (i) completion of the Research or (ii) the
expiration or termination of this Agreement, MBio shall destroy or return to
Abgenix all remaining Abgenix Materials (as Abgenix shall direct), unless
Abgenix otherwise expressly agrees in writing prior to such completion,
expiration or termination. MBio shall not (and shall not attempt or purport to)
file or prosecute in any country any patent application which claims or purports
to claim the Abgenix Materials or any use thereof, without the prior express
written consent of Abgenix.

           b. Unless the parties otherwise expressly agree in writing, [***].
MBio shall use the Research Materials and Inventions, at is address listed
above, for the sole purposes of performing the Research, at its the address
listed above, under commercially and scientifically reasonable containment
conditions, and not for any commercial, business or other use or purpose without
the prior express written consent of Abgenix. Neither party shall transfer or
provide access to the Research Materials and Inventions to any third party or to
any location other than its address set forth above, without the prior express
written consent of the other party. Neither party shall (and neither party shall
attempt or purport to) transfer, assign, sell, have sold, lease, offer to sell
or lease, otherwise transfer title to, or otherwise distribute or license,
sublicense or otherwise commercialize or exploit, any Research Materials and
Inventions (or any products derived thereof), unless the other party otherwise
expressly agrees in


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writing. Promptly upon the expiration or earlier termination of the term of this
Agreement, each party shall destroy all remaining Research Materials and
Inventions, unless the parties otherwise expressly agree in writing prior to
such expiration or termination. Neither party shall (and neither party shall
attempt or purport to) file or prosecute in any country any patent application
which claims or purports to claim the Research Materials and Inventions or any
use thereof unless and until the parties duly execute and deliver the Research
License and Option Agreement in accordance with Section 12 below, without the
prior express written consent of the other party.

      8. No Warranty. The Materials are being provided for research purposes
only solely to facilitate the Research. THE MATERIALS ARE BEING SUPPLIED "AS
IS," WITH NO WARRANTIES, EXPRESS OR IMPLIED, AND ABGENIX EXPRESSLY DISCLAIMS ANY
WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR
NONINFRINGEMENT.

      9. Care in Use of the Materials. The parties acknowledge that the
Materials are experimental in nature and may have unknown characteristics. Each
party agrees to use prudence and reasonable care in the use, handling, storage,
transportation, disposition, and containment of the Materials provided by the
other party. MBio shall not administer the Materials to humans, or file or
submit any regulatory application or other submission to obtain approval
therefor, under any circumstances.

      10. Indemnification. MBio shall indemnify and hold harmless Abgenix from
and against all losses, liabilities, damages and expenses (including reasonable
attorneys' fees and costs) resulting from any claims, demands, actions or other
proceedings by any third party arising from (i) the material breach of any
representation, warranty or covenant by MBio under this Agreement, (ii) the
performance of the Research by MBio, (iii) any use, handling or storage by MBio
of the Abgenix Materials, (iv) any use, handling or storage by MBio of the
Research Materials and Inventions, or (v) any use by MBio of the Confidential
Information of Abgenix. Abgenix shall indemnify and hold harmless MBio from and
against all losses, liabilities, damages and expenses (including reasonable
attorneys' fees and costs) resulting from any claims, demands, actions or other
proceedings by any third party arising from any use by Abgenix of the
Confidential Information of MBio.



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      11. Compliance with Laws. MBio shall use the Materials in compliance with
all applicable laws, guidelines and regulations which are applicable to the
Materials or the use thereof, including without limitation any biosafety
procedures and all safety precautions accompanying the Materials.

      12. Negotiation of Research License and Option Agreement.

           a. During the term of this Agreement, the parties shall negotiate in
good faith, and attempt to reach mutual agreement upon and enter into, the
Research License and Option Agreement. The Research License and Option
Agreement, if entered into between the parties, shall include the terms set
forth on Exhibit C and shall include such other terms and conditions as the
parties mutually agree, including, but not limited to, provisions relating to
intellectual property, confidentiality, publication, representations and
warranties of each party, diligence, indemnification and reporting. During the
term of this Agreement, Abgenix will not engage in negotiations with any third
party, or enter into any agreements with any third party, regarding a
collaboration, license or commercialization of human monoclonal antibodies,
generated through the use of the XenoMouse technology, to Antigen.


           b. The obligations of Abgenix relating to the negotiations described
above or the Research License and Option Agreement are limited to the extent
that Abgenix has, and hereafter will have, the right to grant licenses and other
rights to the XenoMouse Animals and related technology. However, Abgenix
represents and warrants to MBio that it has no present knowledge of any reason
that it does not have the right to grant licenses and other rights to the
XenoMouse Animals to MBio, consistent with the terms and conditions of this
Agreement and the terms contemplated under Exhibit C hereto.

      13. No Conflict. Each party represents that this Agreement does not, and
during the term of this Agreement will not, conflict with any other right or
obligation provided under any other agreement or obligation that such party has
with any third party.



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      14. Term of Agreement. This Agreement shall remain in effect for sixty
(60) days from the date of this Agreement, or such other date as the parties
mutually agree upon in writing. Upon the expiration of this Agreement, Sections
2(a) (other than the first sentence thereof), 3, 5, 6, 7 and 10 shall survive.

      15. Assignment. MBio shall not assign its rights or obligations under this
Agreement, in whole or in part, by operation of law or otherwise, without the
prior express written consent of the Abgenix; provided, however, that MBio may,
without such consent, assign this Agreement and its rights and obligations
hereunder in connection with the transfer or sale of all or substantially all of
its business, or in the event of its merger or consolidation or change in
control or similar transaction. Any permitted assignee shall assume all
obligations of its assignor under this Agreement. Any purported assignment in
violation of this Section 15 shall be void.

      16. Waivers and Amendments. No change, modification, extension,
termination or waiver of this Agreement, or any of the provisions herein
contained, shall be valid unless made in writing and signed by duly authorized
representatives of the parties.



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      17. General. This Agreement contains the entire agreement between the
parties regarding the subject matter of this Agreement and supersedes any
previous understandings, representations, acknowledgements, commitments or
agreements, oral or written, regarding such subject matter. This Agreement shall
be governed by and construed under laws of the State of California, without
regard to its conflicts of laws principles.

      IN WITNESS THEREOF, the parties have caused this Agreement to be duly
executed and delivered as of the date first set forth above.

ABGENIX, INC.                          MILLENNIUM BIOTHERAPEUTICS, INC.

BY: /s/ Raymond Withy                  BY: /s/ John Maraganore
   --------------------------             -----------------------------
   (Signature)                            (Signature)

   Raymond M. Withy, Ph.D.                John Maraganore, Ph.D.

   Vice President,                        Vice President,
   Corporate Development                  General Manager



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                                    Exhibit A

                                Abgenix Materials

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                                    Exhibit B

                                Research Program




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                                    Exhibit C

             Key Terms of the Research License and Option Agreement

I.    Research License and Option Fee

MBIO would pay to Abgenix [***].

II:   Option to Obtain a Product License

With the Agreement execution fee specified in Section 2(c) of the Research
Collaboration Agreement and the above payment of [***], and provided that the
Research License and Option Agreement is executed pursuant to this Agreement,
MBio would secure an option period where Abgenix would reserve exclusivity on
Antigen for MBio. That option period shall extend until [***]. At the end of
this time period or earlier, upon MBio's sole election, MBio would have the
right to obtain a product license by exercising its option and making the
Product License Fee payment, or Abgenix would be released from such exclusivity
on the Antigen.

III.      Product License Fee

MBio would pay to Abgenix [***] upon the exercise of the option for an exclusive
product license.

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V.   Development Milestones

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VI.   Royalties on Woldwide Net Sales

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VIII.  Other:  Terms and Conditions

The Research License and Option Agreement, if entered into between the parties,
shall include the terms set forth on Exhibit C and shall include such other
terms and conditions as the parties mutually agree, including, but not limited
to, provisions relating to intellectual property, confidentiality, publication,
representations and warranties of each party, diligence, indemnification and
reporting.






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