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                                                                    EXHIBIT 99.3

                               LICENSE AGREEMENT


     THIS LICENSE AGREEMENT (the "Agreement") is entered into and effective this
18th day of December 1996, by and between HOUSTON BIOTECHNOLOGY INCORPORATED, a
Delaware corporation ("Licensor"), and MEDAREX, INC., a New Jersey corporation
("Licensee", and together with Licensor the "Parties").


                                  WITNESSETH:

     WHEREAS, Licensor is the exclusive worldwide licensee of certain patent
rights owned by Baylor College of Medicine ("Baylor") pursuant to an agreement
between Licensor and Baylor dated as of June 19, 1984, as amended (the "Baylor
License"), and the nonexclusive licensee of certain patent rights owned by
Sanofi, S.A. ("Sanofi"), pursuant to an agreement between Licensor and Sanofi
dated August 19, 1988, as amended (the "Sanofi License," and together with the
Baylor License, the "Third Party Licenses"), and owns certain patent rights in
its own right all of which patent rights are described on Schedule A hereto
(collectively, the "Patent Rights").

     WHEREAS, Licensor has developed a product coming within such Patent Rights,
the 4197X-RA Immunotoxin (the "Immunotoxin"), for the treatment and prevention
of secondary cataracts (or lens capsule opacification), has developed technical
know how related to the manufacture, testing, formulation, packaging and
administration of the Immunotoxin, has conducted and is conducting preclinical
and clinical trials with the Immunotoxin, and is developing the Immunotoxin for
the purpose of obtaining marketing approval of the U.S. Food and Drug
Administration (the "FDA") and similar agencies in major countries around the
world.

     WHEREAS, Licensee desires to obtain from Licensor a transferable, exclusive
license (except as otherwise provided pursuant to any applicable provisions of
the Third Party Licenses) under the Patent Rights and to use the Licensed Know
How to use, further develop, manufacture, sell or otherwise commercialize the
Licensed Product in the Licensed Territory (as those terms are hereinafter
defined), and Licensor is willing to grant such license to Licensee subject to
the terms and conditions of this Agreement;

     WHEREAS, Licensor and Licensee desire to enter into this Agreement to
define the terms and conditions on which Licensor will license the Licensed
Product under the Patent Rights and Licensed Know How to Licensee;

     NOW, THEREFORE, for and in consideration of the mutual covenants and
conditions hereinafter set forth, the parties agree as follows:
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                                 1. DEFINITIONS

     Whenever used in this Agreement, the following terms shall have the
meanings set forth below:

     (a) "Affiliate" shall mean any person or entity that controls, is
controlled by, or is under common control with, any other person or entity.  For
purposes of this definition, "control" means beneficial ownership, directly or
indirectly, of more than fifty percent (50%) of the outstanding voting
securities or equity of such entity (or other equivalent ownership interest with
respect to an entity other than a corporation).

     (b) "Improvement" shall mean any development by Licensor or Licensee,
including know how, that enhances the effectiveness of the Licensed Product,
excluding distinguishable compounds.  For purposes of this Agreement, the
Refined Immunotoxin shall constitute an Improvement to the Licensed Product.

     (c) "Invention" shall mean a patentable discovery related or relating to
the Licensed Product made by Licensor or Licensee during the term of this
Agreement.

     (d) "Licensed Know How" shall mean all information in the possession of
Licensor, in addition to the Patent Rights, relating to the Licensed Product,
whether or not patentable, constituting materials, methods, processes, trade
secrets, techniques and data, and which Licensor is free to license or disclose
to Licensee without violating existing contractual obligations to third parties,
or contractual obligations entered into after the date of this Agreement
pursuant to which new information is obtained, licensed or developed; provided,
however, Licensed Know How shall not include any information independently
developed by Licensee prior to, during or after the term of this Agreement.

     (e) "Licensed Product" shall mean the Immunotoxin and Improvements thereto
(including the Refined Immunotoxin).

     (f) "Licensed Territory" shall mean North America.

     (g) "Refined Immunotoxin" shall mean Licensor's 4197X-RA immunotoxin in its
most refined form, consisting of a murine monoclonal antibody (4197X) conjugated
to a polypeptide toxin, ricin A(RA) chain.  The linkage of ricin A to the
antibody is through a cleavable disulfide bond to form the immunotoxin.  The
linkage is accomplished by chemical derivatization of the antibody with SPDP (N-
succinimidyl 3.(2-pyridyldithio) propionate), followed by reaction with ricin A.

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                                 2. GRANT OF LICENSE

          2.1  Licensor hereby grants to Licensee a transferable, exclusive
license under the Patent Rights to make, have made, import, use, further
develop, distribute, offer for sale, sell and otherwise commercialize directly
or indirectly the Licensed Product in the Licensed Territory and an exclusive
license to use the Licensed Know How in the Licensed Territory (the "License").
Licensee shall have the right and license under the Patent Rights to manufacture
and have manufactured, the Licensed Product (which shall include the right to
use the Licensed Know How in connection with such manufacture).

          2.2  Within thirty (30) days of the date Licensee notifies Licensor of
Licensee's election to manufacture the Licensed Product, or at such other time
or as the Parties agree (the "Notice Date"), Licensor will deliver to Licensee
all Licensed Know How relating to the manufacture of the Licensed Product
existing, as of the Notice Date.  In such event, the Parties shall cooperate
with each other in order that Licensee may initiate the manufacture of the
Licensed Product as soon as practicable and shall take such actions as are
appropriate to achieve such goals.

          2.3  Licensee shall not use the Licensed Product for purposes other
than those specifically authorized herein, nor make any sale of Licensed Product
outside the Licensed Territory.

          2.4  The License granted hereby is transferable by Licensee, directly
or indirectly, and Licensee may grant any sublicenses of the Licensed Product or
the Licensed Know How, subject only to any applicable limitations pursuant to
the Third Party Licenses.

          2.5 The License granted herein shall be subject to termination only as
set forth in Section 6 hereof.


                        3. COOPERATION AMONG THE PARTIES

          3.1  Once each calendar quarter, each Party shall deliver to the other
Party a written report as to such Party's efforts and accomplishments during the
preceding quarter with respect to the Licensed Product and the Licensed Know How
in successfully completing such Party's clinical trials and other activities for
the purpose of obtaining the approval of the FDA or any similar agency for the
manufacture, sale and use of the Licensed Product and such Party's plans for the
succeeding quarter.

          3.2  Each Party hereby grants the other Party a right of access to and
use for the purposes of this Agreement of all experimental or other data in the
possession of or reasonably available to such Party which relate in any manner
to the Licensed Product, including without limitation, all data which Baylor,
Sanofi or such Party have provided to the FDA  or any other

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state, federal, foreign or local regulatory authority which relate in any manner
to the Licensed Product.  Nothing in this section shall require either Party to
violate any confidentiality or other similar obligation.

          3.3  Each Party shall promptly provide the other Party and shall
continue to provide the other Party, during the term of this Agreement, with all
requested information relating to (i) pharmacological, toxicological or clinical
data, (ii) formulative or analytical data, and (iii) such other chemical,
physical or biological data which such Party may now or in the future possess or
control which relates in any manner to the Licensed Product and which such Party
is permitted to disclose to the other Party.

          3.4  In the event either Party develops any Improvement to the
Licensed Product, it shall promptly disclose such Improvement to the other
Party.


                        4. ROYALTY PAYMENTS; COMPLIANCE

          4.1  The Licensee shall not be obligated to make any royalty payments
to Licensor.  Licensee shall make the royalty payments required to be made under
the Baylor License and the Sanofi License directly to Baylor and Sanofi,
respectively.

          4.2  Licensee shall comply with all other provisions of the Third
Party Licenses to the extent they apply to the Licensed Product in the Licensed
Territory.


                                 5. INVENTIONS

          5.1  Any Invention invented by either Party shall be the exclusive
property of such Party and shall be licensed to the other Party without
additional cost.

          5.2  Each Party shall promptly notify the other Party of the existence
of any Invention invented by it.  In the event the Inventing Party elects not to
obtain patents on such Invention outside the territory in which the Inventing
Party has the rights to commercialize the Licensed Product, the Inventing Party
shall provide the other Party the right and opportunity to do so in the
Inventing Party's name and at the other Party's expense prior to any disclosure
thereof.

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                                 6. TERMINATION

          6.1  This Agreement shall continue in full force and effect until
terminated in accordance with a provision of this Section 6.

          6.2 This Agreement shall terminate automatically on the written
agreement of Licensor and Licensee to do so.

          6.3 This Agreement shall terminate automatically upon the termination
of the Baylor License.

          6.4  In the event that either Licensor or Licensee shall commit a
Material Breach (as hereinafter defined) of the terms and conditions of this
Agreement, and shall fail to cure such Material Breach within sixty days of
written notice thereof (except in the case of a Material Breach described in
clause (i) below, with respect to which no notice of breach shall be required
and such Material Breach shall be actionable unless cured within five days from
the date on which performance is required), the nondefaulting party may, at its
option, and without limiting the other remedies available to such party,
terminate this Agreement by sending written notice of termination to the
defaulting party.  For the purposes of this Agreement, a Material Breach shall
be (i) the failure of a Party to pay sums arising under this Agreement owed to
another Party hereto when such payment is due; (ii) the breach by a Party hereto
of a covenant, representation or warranty contained herein, which breach has a
material adverse effect on the ability of the breaching Party to perform its
obligations hereunder; or (iii) the breach by a Party hereto of a covenant,
representation or warranty contained herein, which breach deprives the
nonbreaching Party hereto of a material benefit afforded such nonbreaching party
under this Agreement.

          6.5  Licensor shall notify both Baylor and Sanofi that any notice
given by Baylor or Sanofi to Licensor under the Third Party Licenses shall also
be given to Licensee and a copy of any notice received by either Party under the
Third Party Licenses shall be promptly forwarded to the other Party.  In the
event either Party shall have received a notice from either Baylor or Sanofi
that such Party is in breach of a Third Party License (a "Breaching Party"),
such Breaching Party shall cure said breach within one-half of the time allowed
by the applicable cure period.  If such Breaching Party fails to cure a breach
of a Third Party License within said time period, then and only then, the other
Party (a "Curing Party") may take such action as such Party deems appropriate to
cure such breach.  In such event, the Breaching Party shall have one (1) year
from the date the breach is cured in which to repay the Curing Party three (3)
times the amount expended by the Curing Party to cure said breach (the "Curing
Amount").  If the Breaching Party fails to repay the Curing Party the Curing
Amount within such one (1) year period, the Curing Party shall succeed to all of
the rights, title and interests of the Breaching Party in and to the Third Party
License.  Notwithstanding the foregoing, in the event a Curing Party shall cure
a Breaching Party's breach of a Third Party License more than once then the

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Curing Party shall succeed to all of the rights, title and interests of such
Breaching Party in and to the Third Party License.

          6.6  In the event of termination of the Agreement for any reason
whatsoever, neither Licensor nor Licensee shall thereby be discharged from any
liability or obligation to the other which became due or payable prior to the
effective date of such termination.

          6.7  In the event of termination of the Agreement by Licensor on
account of Licensee's breach of this Agreement and failure to cure such breach:

          (a) If Licensee then possesses Licensed Product or has accepted orders
therefor, Licensee shall have the right to sell its inventories thereof and
market such fully manufactured Licensed Product in order to fulfill such
accepted orders, subject to the obligation of Licensee to pay the earned royalty
therefor as provided in Section 4 of this Agreement;

          (b) Licensee shall discontinue the use, marketing and sale of Licensed
Product, and Licensee shall immediately discontinue use of the words "Baylor"
and "Baylor College of Medicine" or any language which would connect sales of
product by Licensee with or imply the sponsorship of Baylor; and

          (c) All rights licensed by Licensor to Licensee hereunder shall revert
to Licensor, and Licensee agrees to execute all instruments necessary and
desirable to revest said rights in Licensor.

          6.8  This Agreement shall not terminate in the event of the
acquisition of Licensor by a third party or the sale by Licensor of
substantially all of its assets.


                       7.  INFRINGEMENT BY THIRD PARTIES

          7.1  Licensor and Licensee each shall have the right to protect the
rights to the Licensed Products, Patent Rights and Licensed Know How granted
herein in the territory in which such Party has the rights to commercialize the
Licensed Product.

          7.2  When either Licensor or Licensee becomes aware that a third party
is or may be substantially infringing the Licensed Product, Patent Rights and
Licensed Know How, Licensor or Licensee as the case may be, shall give the other
written notice thereof, which notice shall fully describe the actual or
potentially infringing actions by such third party.

          7.3  Within a reasonable period of time following the receipt of the
notice described in Section 7.2 above, Licensor and Licensee agree to consult
with one another in an effort to determine whether a reasonably prudent person
would institute litigation to enforce the Licensed Product, Patent Rights and
Licensed Know How in question in light of all relevant business and

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economic factors (including, but not limited to, the projected cost of such
litigation, the likelihood of success on the merits, the probable amount of any
damage award, the prospects for satisfaction of any judgment against the alleged
infringer, the possibility of counterclaims against Licensor or Licensee, the
diversion of human and economic resources, the impact of any possible adverse
outcome on Licensor or Licensee and the effect any publicity might have on
Licensor and Licensee and the respective reputations and goodwill of Licensor
and Licensee).  The Party in whose territory the infringement has occurred, at
its sole option, may file suit or take such other action as such Party deems
appropriate to enforce the Licensed Product, Patent Rights and Licensed Know How
Licensed hereunder on behalf of itself and the other Party.  If the Party in
whose territory the infringement has occurred shall determine not to take any
such enforcement action, then and only then, the other Party may file suit or
take such other action as it deems appropriate to enforce the Licensed Product,
Patent Rights and Licensed Know How on behalf of itself and the other Party.
Notwithstanding the foregoing, in the event a Third Party License, by its terms,
requires that litigation or other action be instituted to enforce the Licensed
Product, Patent Rights and Licensed Know How, the Party in whose territory the
infringement has occurred shall file suit or take such other action as it deems
appropriate to enforce the Licensed Product, Patent Rights and Licensed Know
How.  If the Party in whose territory the infringement has occurred fails to
take action to enforce the Licensed Product, Patent Rights and the Licensed Know
How as required by the Third Party License, then the provisions of Section 6.5
above relating to a breach under the Third Party License shall apply.

          7.4  Any money damages recovered for an infringement shall go to the
Party bringing and maintaining the enforcement action or otherwise terminating
the infringement.

          7.5  In any enforcement action, including a suit or dispute involving
an infringement the Parties shall cooperate fully, and upon the request and at
the expense of the Party bringing suit against the infringer, the other party
shall make available to the Party bringing suit at reasonable times and under
appropriate conditions all relevant personnel, records, papers, information,
samples, specimens, and the like which are in its possession.


                              8.  INDEMNIFICATION

          8.1  Licensee shall hold harmless and indemnify Licensor and its
Affiliates, officers, directors, employees and agents (collectively, "Licensor
Indemnified Persons") from and against any claims, demands, or causes of action
whatsoever, including without limitation those arising on account of any injury
or death of person or damage to property arising from or related to the exercise
or practice of the License granted hereunder by Licensee or its officers,
employees, agents or representatives; provided, however, that the following is
excluded from Licensee's obligation to indemnify and hold harmless the Licensor
Indemnified Persons:

           (a) the gross negligence of any Licensor Indemnified Person,
including resulting injury or property damage;

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          (b) the willful malfeasance of any Licensor Indemnified Person; or

          (c) any claims that the Licensed Product or Licensed Know How
infringes or otherwise violates the proprietary rights of any third party.

          8.2  Licensor shall hold harmless and indemnify Licensee and its
Affiliates, officers, directors, employees and agents from and against any
claims, demands, or causes of action whatsoever, including without limitation
those arising on account of any injury or death of persons or damage to property
arising from or related to:

          (a) the gross negligence of any Licensor Indemnified Person, including
resulting injury or property damage;

          (b) the willful malfeasance of any Licensor Indemnified Person;

          (c) any Material Breach (or any claim act or omission that would
constitute a Material Breach) by Licensor of any of the terms and conditions of
this Agreement, including without limitation any Material Breach of Licensor's
representations or warranties under this Agreement; or

          (d) any claims that the Licensed Product infringes or otherwise
violates the proprietary rights of any third party.

          8.3  Licensor and Licensee each agree to maintain policies of product
liability insurance covering their respective roles in the design, manufacture
and sale of Licensed Product, in such amounts as they may agree from time to
time.


                           9.  USE OF BAYLOR'S NAME

          9.1  Licensee shall not use any trademark, service mark, trade name,
or the name of "Baylor" or "Baylor College of Medicine" for advertising or other
purposes, without prior express written consent of Baylor.


                         10.  CONFIDENTIAL INFORMATION

          10.1  Licensor and Licensee each agree that all information contained
in documents marked "confidential" that are furnished by one Party to the other
for purposes of this Agreement shall be received in strict confidence, be used
only for the purposes of this Agreement, and not be disclosed by the recipient
Party (except as required by law or court order) its agents or employees without
the prior written consent of the other Party, unless such information:

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          (a) was in the public domain at the time of disclosure;

          (b) later became part of the public domain through no act or omission
of the recipient party, its employees, agents, successors or assigns;

          (c) was lawfully disclosed to the recipient party by a third party
having the right to disclose it, without obligation of confidentiality;

          (d) was independently developed by the recipient party prior to the
time of disclosure; or

          (e) is required to be submitted to a government agency.

          10.2  Each Party's obligation of confidentiality hereunder shall be
fulfilled by using reasonable measures, but no less than the same degree of care
with the other Party's confidential information as it uses to protect its own
confidential information.  This obligation shall apply to each disclosure for
the term of this Agreement and for the term of this Agreement and for three
years thereafter.


                        11.  WARRANTIES AND DISCLAIMERS

          11.1 Licensor hereby represents and warrants to Licensee :

          (a) Licensor is a corporation, validly existing and in good standing
under the laws of the State of Delaware.

          (b) The execution, delivery and authority to execute and deliver this
Agreement have been duly authorized by all necessary action on the part of
Licensor.

          (c) Licensor has the power and authority to execute and deliver this
Agreement and to perform its obligations under this Agreement.

          (d) Except as set forth herein or pursuant to the Codevelopment and
License Agreement between Licensor and Santen Pharmaceutical Co., Ltd. dated
December 29, 1995, Licensor has not encumbered, restricted, transferred or
otherwise burdened the Patent Rights.

          (e) All rights licensed to Licensor by third parties and necessary for
Licensee to exercise the License granted under this Agreement are in current
force and effect.  Licensor covenants and agrees to use commercially reasonable
best efforts to maintain all such third party licenses in full force and effect
during and after the term of this Agreement as necessary for Licensee to
exercise its rights hereunder.

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          11.2  Except as otherwise provided in this Agreement, Licensor hereby
disclaims and negates any and all warranties, whether express or implied, with
respect to the Licensed Product or any rights hereunder transferred, including
but not limited to, an IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR ANY
PARTICULAR PURPOSE.


                                 12.  GENERAL

          12.1  This Agreement constitutes the entire and only agreement between
the parties with respect to the subject matter hereof, and all other prior
negotiations, representations, agreements, and understandings are superseded
hereby.  No agreements altering or supplementing the terms hereof may be made
except by means of a written document signed by the duly authorized
representatives of the parties.

          12.2  All notices, requests, claims, demands and other communications
hereunder shall be in writing and shall be given (and shall be deemed to have
been duly given upon receipt) by delivery in person, by cable, telecopy,
telegram or telex or by registered or certified mail (postage prepaid, return
receipt requested) to the respective parties at the following addresses (or at
such other address for a party as shall be specified by like notice):

                      Houston Biotechnology Incorporated
                      3608 Research Forest Drive
                      The Woodlands, Texas 77381
                      Attn:  Mr. J. Russell Denson
                             President

          In the case of Licensee, notice must be addressed to:

                      Medarex, Inc.
                      1545 Route 22 East
                      Annandale, New Jersey 08801
                      Attn:  Mr. Donald L. Drakeman
                             President

          12.3  Licensee shall comply with all applicable laws and regulations
in connection with its activities pursuant to this Agreement.

          12.4 This Agreement shall be construed and enforced in accordance with
the laws of Delaware.

          12.5  Failure of a party hereto to enforce a right under this
Agreement shall not act as a waiver of that right or the ability to later assert
that right relative to the particular situation involved.

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          12.6 Headings included herein are for convenience only and shall not
be used to construe this Agreement.

          12.7  If any provisions of this Agreement shall be found by a court to
be void, invalid or unenforceable, the same shall be reformed to comply with
applicable law or stricken if not so conformable, so as not to affect the
validity or enforceability of the remainder of this Agreement.

          12.8  It is agreed that the relationship of the Licensee to Licensor
in the performance of this Agreement is as an independent licensee and that the
Licensee is not an agent of Licensor.  Licensee agrees to refrain from
representing itself as being the agent of Licensor in performing or acting
pursuant to this Agreement.  Licensee shall not have the power or authority to
bind or otherwise commit Licensor and shall not attempt to do so.


ENTERED INTO AND EFFECTIVE AS OF THE DATE SET FORTH ABOVE.

                                 HOUSTON BIOTECHNOLOGY INCORPORATED


                                 By: /s/ J. RUSSELL DENSON
                                    ------------------------------------ 
                                    J. Russell Denson
                                    President

                                 MEDAREX, INC.


                                 By: /s/ DONALD L. DRAKEMAN
                                    ------------------------------------ 
                                    Donald L. Drakeman
                                    President

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