Exhibit
10.6


Confidential Materials
omitted and filed separately with the


Securities
and Exchange Commission. Asterisks denote omissions.


Momenta Pharmaceuticals,
Inc.


675 West Kendall Street


Cambridge,
MA 02142


October 18, 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, a Fifth Amendment dated
August 5, 2006 and a letter Agreement dated August 10, 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, Momenta has
entered into a Memorandum of Understanding (“MOU”) with Sandoz AG (“Sandoz”)
dated July 25, 2006 relating to the development and commercialization of four
follow-on and/or complex generic products for sale in specified regions of the
world (each, a “Program”).  For
reference, these programs are: 1) injectable versions of enoxaparin (“ENX”) for
the European Union (the “ENX Program”); 2) X; 3) Y; and 4) Z.


In connection with the MOU,
on September 6, 2006, Novartis Pharma AG, an affiliate of Sandoz (“Novartis”),
made an investment in Momenta, purchasing $75,000,000 of the common stock of
Momenta at a premium to market.  Under
the MIT-Momenta Agreement, MIT is entitled to [**]% of CORPORATE PARTNER INCOME
and/or SUBLICENSE INCOME which is received by Momenta in respect of sublicenses
of the LICENSED PROCESSES.  Both
CORPORATE PARTNER INCOME and SUBLICENSE INCOME include premiums received by
Momenta on sales of its equity.









 



As we have discussed, while
we anticipate using the LICENSED PROCESSES for a regulatory or commercial
release specification purpose in connection with the ENX Program, it is not yet
clear whether the LICENSED PROCESSES will have any relevance for the three
other Programs.  Since the premium paid
by Novartis is in respect of all four Programs, MIT and Momenta have agreed
that the appropriate payment to MIT at this point in time is one-fourth of
[**]% of the premium.  Such amount comes
to $[**] (one-fourth of $[**], which is [**]% of the premium of $[**]).


Notwithstanding the
foregoing, should the LICENSED PROCESSES be used for a regulatory, commercial
release specification or any other commercial (that is, excluding basic
research and development) purpose in connection with any of the other three
Programs, Momenta shall pay to MIT an additional $[**] for each such Program up
to a maximum of $[**].  On July 1 and
January 1 of each year, commencing with July 1, 2007, Momenta will update MIT
on its assessment regarding whether the LICENSED PROCESSES will have any
relevance to the remaining Programs.


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/Richard
  P. Shea

  	
   

  
	
   

  	
  Richard P. Shea

  
	
   

  
	
   

  
	
  AGREED:

  
	
   

  
	
  MASSACHUSETTS
  INSTITUTE OF TECHNOLOGY

  
	
   

  
	
   

  
	
  By:

  	
    /s/Lita
  Nelson

  	
   

  
	
   

  	
  Lita L. Nelson,
  Director

  
	
   

  	
  Technology
  Licensing Office

  
						



 



 2