EXHIBIT 10.1


EXECUTION COPY






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EXCHANGE ACT OF 1934, AS AMENDED.


AMENDMENT
TO

CROSS-LICENSE AGREEMENT


THIS AMENDMENT TO CROSS-LICENSE AGREEMENT
(the “Amendment”) is made as of April
25th, 2007 (the “Amendment Effective Date”) between Pfizer
Inc, a Delaware corporation having an office at 235 East 42nd Street, New York,
New York 10017, and its Affiliates (“Pfizer”),
and Medarex, Inc., a New Jersey corporation with a business address at 707
State Road, Princeton, New Jersey 08540 (“Medarex”).  Pfizer and Medarex each may be referred to
herein individually as a “Party”
or collectively as the “Parties.”


RECITALS


A.   Pfizer and Medarex entered into a
Cross-License Agreement dated September 15, 2004 (the “Cross-License
Agreement”).


B.   The Parties now wish to amend the Cross-License
Agreement to include certain additional patent claims and Patents.


NOW,
THEREFORE, in consideration of the foregoing premises and for
other good and valuable consideration, the receipt and sufficiency of which are
acknowledged, the Parties, intending to be legally bound, do hereby agree as
follows:


1.             The definition of
Covered Patent is deleted and replaced with the following new definition:


“Covered
Patent” means any Patent to the extent that it claims (a) an
Antibody, or a group of Antibodies, or the Exploitation of such Antibody or
group of Antibodies, (b) a composition, whether alone or in combination with an
article of manufacture, comprising one or more Antibodies or the Exploitation
of such a composition, (c) a nucleic acid sequence or host cell that
specifically codes for, incorporates, expresses or secretes an Antibody, (d)
the use of such a nucleic acid sequence or host cell to make (including to
manufacture, formulate, purify, express, recover and secrete) an Antibody, (e)
a method of making (including manufacturing, formulating, purifying,
expressing, recovering, and secreting) (i) an Antibody, (ii) a composition
comprising one or more Antibodies or (iii) CTLA-4; (f) a method of using
an Antibody or a composition comprising one or more Antibodies; or (g) CTLA-4.


For the avoidance of doubt, the following language has been deleted
from the definition: “Covered Patents shall not include any Patents to the
extent that they claim any method of manufacturing Licensed Products.”






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2.             Schedule A, Medarex
Patents and Patent Applications, is deleted and replaced with the attached
Schedule A.


3.             Schedule B, Pfizer
Patents and Patent Applications, is deleted and replaced with the attached
Schedule B.


4.             The definitions of
Medarex Patents and Pfizer Patents are amended to read as follows:


“Medarex Patents” means (a) all Covered
Patents Controlled by Medarex (other than through a license from Bristol-Myers
Squibb Company (“BMS”)) or its Affiliates as of the
Amendment Effective Date that would be infringed (and with respect to Patent
applications, would be infringed after issuance) by the Exploitation of a
Pfizer Product in the absence of the license grant set forth in Section 2.1.2,
including the Patents set forth in Schedule A hereto, and (b) all
Covered Patents Controlled by Medarex or its Affiliates (other than through a
license from BMS) that are filed either from such Covered Patents in clause (a)
above or from an application claiming priority therefrom to the extent of
claims not directed to new matter, but in each case ((a) and (b)) excluding any
Medarex Excluded Patents.


“Pfizer Patents” means (a) all Covered
Patents Controlled by Pfizer or its Affiliates as of the Amendment Effective
Date that would be infringed (and with respect to Patent applications, would be
infringed after issuance) by the Exploitation of a Medarex Product in the
absence of the license grant set forth in Section 2.1.1, including the Patents
set forth in Schedule B hereto, and (b) all Covered Patents Controlled
by Pfizer or its Affiliates that are filed either from such Covered Patents in
clause (a) above or from an application claiming priority therefrom to the
extent of claims not directed to new matter, but in each case ((a) and (b))
excluding any Pfizer Excluded Patents.


5.             The definition of Medarex
Excluded Patents and Pfizer Excluded Patents are amended to read as follows:


“Medarex
Excluded Patents” means (a) Mice-Related Patents, (b) Allison
Patents, and (c) claims of any Patents that Medarex or any of its Affiliates
own, have under license or otherwise Control to the extent that they (i)  claim (A) one or more particular Antibodies where such
particular Antibody(ies) is specifically defined by the amino acid sequence of
CDR 1, 2 and 3 of either the heavy or the light chain variable region of such
Antibody(ies) (each such specifically defined Antibody being a “Particular Antibody”) or the Exploitation of such Particular
Antibody(ies), (B) a composition comprising one or more such Particular
Antibodies or the Exploitation of such a composition, (C) a nucleic acid sequence
or host cell that specifically codes for, incorporates, expresses or secretes one
or more Particular Antibodies, (D) the use of a nucleic acid sequence, host
cell or other composition of matter to make (including to manufacture,
formulate, purify, express, recover and secrete) one or more Particular Antibodies,
(E) a method of making (including manufacturing, formulating, purifying,
expressing, recovering, and secreting) one or more Particular Antibodies or a
composition comprising such Particular Antibody(ies), or (F) a method of using one
or more Particular Antibodies or a composition comprising such Particular
Antibody(ies), or  (ii) validly claim priority to a 






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Patent filed on or
before September 15, 2004 and claim one or more Particular Antibodies, whether
specifically or generally, together with, or otherwise in combination with, a
specific therapeutic or prophylactic composition of matter, whether in a fixed
dosage form or as a combination therapy, wherein the composition of matter is
recited in the claim by a specific name, specific compositional description,
specific protein structure or specific chemical structure, or the Exploitation
of the foregoing, or (iii) validly claim priority to a Patent filed after
September 15, 2004 and claim one or more Antibodies, whether specifically or
generally, together with, or otherwise in combination with, one or more
antibodies (other than an Antibody) or fragment(s) thereof, whether in a fixed
dosage form or as a combination therapy, or the Exploitation of the foregoing.  Without limiting the foregoing, Medarex
Excluded Patents shall include any Patents to the extent that they claim or
cover [ * ].


“Pfizer
Excluded Patents” means claims of any Patents that Pfizer or
any of its Affiliates own, have under license or otherwise Control to the
extent that they (a)  claim (i) one
or more Particular Antibodies, or the Exploitation of such Particular Antibody(ies),
(ii) a composition comprising one or more Particular Antibodies or the
Exploitation of such a composition, (iii) a nucleic acid sequence or host cell
that specifically codes for, incorporates, expresses or secretes one or more
Particular Antibodies, (iv) the use of a nucleic acid sequence or host cell or
other composition of matter to make (including to manufacture, formulate,
purify, express, recover and secrete) one or more Particular Antibodies, (v) a
method of making (including manufacturing, formulating, purifying, expressing,
recovering, and secreting) one or more Particular Antibodies or a composition
comprising such Particular Antibody(ies), or (vi) a method of using one or more
Particular Antibodies or a composition comprising such Particular Antibody(ies),  or (b) validly claim priority to a Patent filed on or
before September 15, 2004 and claim one or more Particular Antibodies, whether
specifically or generally, together with, or otherwise in combination with, a
specific therapeutic or prophylactic composition of matter, whether in a fixed
dosage form or as a combination therapy, wherein the composition of matter is
recited in the claim by a specific name, specific compositional description,
specific protein structure or specific chemical structure, or the Exploitation
of the foregoing, or (c) validly claim priority to a Patent filed after
September 15, 2004 and claim one or more Antibodies, whether specifically or
generally, together with, or otherwise in combination with, one or more
antibodies (other than an Antibody) or fragment(s) thereof, whether in a fixed
dosage form or as a combination therapy, or the Exploitation of the foregoing.  Without limiting the foregoing, Pfizer
Excluded Patents shall include any Patents to the extent that they claim or
cover [ * ] including claims that validly
claim priority to [ * ].


6.             Section 2.1.1 is
amended to add the following sentence at the end of the Section: “Nor does
anything in this Agreement provide rights to Medarex or any of its Affiliates
or Sublicensees/Licensees to use any tangible quantities of biological
materials developed by, or on behalf of, Pfizer.”


7.             Section 2.1.2 is
amended to add the following sentence at the end of the Section: “Nor does
anything in this Agreement provide rights to Pfizer or any of its Affiliates or







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Sublicensees/Licensees to
use any tangible quantities of biological materials developed by, or on behalf
of, Medarex.”


8.             Section 3.1(h) is
amended to read as follows:


“; and (h) as of the
Effective Date, to the best of Pfizer’s knowledge,  Schedule
B hereto lists Covered Patents owned or controlled by Pfizer or
its Affiliates and neither Pfizer nor its Affiliates has any agreement or
arrangement with a Third Party with respect to any Covered Patents that affects
its Control of the Pfizer Patents or would otherwise adversely affect Medarex’s
rights with respect to such Covered Patents under this Agreement.”


9.             Section 3.2(h) is
amended to read as follows:


“; and (h) as of the
Effective Date, to the best of Medarex’s knowledge, Schedule
A hereto lists Covered Patents owned or controlled by Medarex or
its Affiliates and neither Medarex nor its Affiliates has any agreement or
arrangement with a Third Party with respect to any Covered Patents that affects
its Control of the Medarex Patents or would otherwise adversely affect Pfizer’s
rights with respect to such Covered Patents under this Agreement.”


10.           For purposes of this
Amendment, the representations, warranties and covenants of the Parties in
Sections 3.1 and 3.2 are made again as of the Amendment Effective Date.  Further, Medarex represents and warrants to
Pfizer as of the Amendment Effective Date that, to Medarex’s knowledge, neither
Medarex nor any of its Affiliates owns or Controls any Patents (other than the
Medarex Patents and other than Patents obtained by a license from BMS) that
would be infringed (or, with respect to Patent applications, would be infringed
after issuance) by the Exploitation of a Pfizer Product and Pfizer represents
and warrants to Medarex as of the Amendment Effective Date that, to Pfizer’s
knowledge, neither Pfizer nor any of its Affiliates owns or Controls any
Patents (other than the Pfizer Patents) that would be infringed (or, with
respect to Patent applications, would be infringed after issuance) by the
Exploitation of a Medarex Product.


11.           This Amendment to
Cross-License Agreement shall not take effect unless and until BMS and Pfizer
shall have concurrently executed that certain License Agreement covering
certain BMS CTLA4 intellectual property.  Pfizer shall promptly notify Medarex in
writing when the License Agreement is executed. 


12.           This Amendment amends
the terms of the Cross-License Agreement and is deemed incorporated into, and
governed by all other terms of, the Cross-License Agreement.  Except as expressly amended hereby, the
Cross-License Agreement is not amended, modified or affected by this Amendment,
and the Cross-License Agreement and the rights and obligations of the Parties
thereunder remain in full force and effect in all respects.


13.           All capitalized terms
used but not defined in this Amendment shall have the meanings ascribed to them
in the Cross-License Agreement.






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RULE 24B-2 OF THE SECURITIES EXCHANGE ACT OF 1934, AS AMENDED.



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14.           This Amendment may be executed in any number of counterparts, each of
which shall be deemed an original but all of which together shall constitute
one and the same instrument.


[Signature Page Follows]






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IN WITNESS
WHEREOF, duly-authorized representatives of the Parties have signed this Amendment
to Cross-License Agreement as a document under seal as of the Amendment Effective
Date.


	
  MEDAREX,
  INC.

  	
   

  	
  PFIZER INC

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
  By: 

  	
  /s/ Ronald
  Pepin, Ph.D.

  	
   

  	
   

  	
  By: 

  	
  /s/ John DeYoung

  	
   

  
	
   

  	
   

  	
   

  
	
  Name: Ronald Pepin, Ph.D.

  	
   

  	
  Name: John DeYoung

  
	
   

  	
   

  	
   

  
	
  Title: Senior
  Vice President,

  	
   

  	
  Title: Attorney-in-Fact

  
	
   

  	
   

  	
   

  
	
  Business
  Development

  	
   

  	
   

  
							







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Schedule
A


Medarex
Patents and Patent Applications


[ * ]






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Schedule
B


Pfizer
Patents and Patent Applications


Note:
The Patents marked with an asterisk on this Schedule B are owned jointly by
Pfizer,  Inc. and Abgenix, Inc.


[ * ]


*U.S. Patent No.
6,682,736


Issued: January
27, 2004


Titled: “Human
Monoclonal Antibodies to CTLA-4”


Inventors: Douglas
Charles HANSON, Mark Joseph NEVEU, Eileen Elliott MUELLER,           

Jeffrey Herbert HANKE, Steven Christopher GILMAN, C. Geoffrey DAVIS, and Jose 

Ramon CORVALAN


Assignee: Abgenix,
Inc. (Fremont, CA) and Pfizer, Inc. (New York, NY)


U.S.S.N.
09/472,087 filed on December 23, 1999


Claiming priority
from U.S.S.N. 60/113,647


[ * ]






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