Exhibit 10.1


Confidential
Materials omitted and filed separately with the

Securities and Exchange Commission. 
Asterisks denote omissions.


MOMENTA LETTERHEAD


 


August 4, 2006


Ms. Lita Nelsen, Director

Technology Licensing Office

Massachusetts Institute of Technology

77 Massachusetts Avenue

Cambridge, MA  02139-4307


	
  Re:

  	
   

  	
  Amended and Restated Exclusive Patent License

  	
   

  
	
   

  	
   

  	
  Agreement/M.I.T. License Agreement #4908236

  	
   

  



 


Dear Lita:


This letter is in
reference to the Amended and Restated Exclusive Patent License Agreement by and
between Massachusetts Institute of Technology (“MIT”) and Momenta
Pharmaceuticals, Inc. (“Momenta”) dated as of November 1, 2002 and as amended
by a First Amendment dated November 1, 2002, letter agreements dated September
12, 2003 and October 22, 2003, a Second Amendment dated November 19, 2003, a
Third Amendment dated April 2, 2004, a Fourth Amendment dated July 17, 2004 and
a Fifth Amendment dated August 5, 2006 (collectively, the “MIT-Momenta
Agreement”).  Capitalized terms used
herein and not otherwise defined shall have the meanings given such terms in
the MIT-Momenta Agreement.


As you know, we have
entered into a Collaboration and License Agreement with Sandoz N.V. (formerly
Biochemie West Indies, N.V.) and Sandoz, Inc. (formerly Geneva Pharmaceuticals,
Inc.) (collectively, the “Sandoz Parties”) as of November 1, 2003 relating to
the development and commercialization of enoxaparin (the “Enoxaparin Agreement”),
a copy of which agreement has been previously provided to MIT.  Although we have used technology licensed to
Momenta to characterize enoxaparin, under the terms of the MIT-Momenta
Agreement there would be no royalties payable to MIT under the MIT-Momenta
Agreement as a result of such use because the enoxaparin product under
development does not constitute a LICENSED PRODUCT.


Based upon our
discussions and for good and valuable consideration, receipt of which is
acknowledged by both parties, Momenta hereby agrees to pay to MIT [**] percent
([**]%) of all payments, if any, that it receives from the Sandoz Parties under
Section 4.5 of the Enoxaparin Agreement. 
Such payments shall be made to M.I.T. within sixty (60) days of the end
of each REPORTING PERIOD and in accordance with Section 4.2 of the MIT-Momenta Agreement.









 



 


Ms. Lita Nelsen, Director

August 4, 2006

Page 2


 


Notwithstanding the
foregoing, the parties agree that the foregoing [**] percent ([**]%) payment
shall be payable only with respect to enoxaparin products that do not
constitute LICENSED PRODUCTS.  If COMPANY
should commercialize an enoxaparin product that does constitute a LICENSED
PRODUCT, the foregoing [**] percent ([**]%) payment shall not apply and the
royalty provisions of the MIT-Momenta Agreement governing LICENSED PRODUCTS
shall apply to such enoxaparin product.


If the foregoing
accurately sets forth our agreement, please indicate so by countersigning this
letter in the space provided below.


Sincerely yours,


MOMENTA PHARMACEUTICALS, INC.


	
  By:

  	
  /s/ Alan L. Crane

  	
   

  



 


AGREED:


MASSACHUSETTS INSTITUTE OF TECHNOLOGY


	
  By:

  	
  /s/ Lita Nelson