Additional Field Force Agreement ? Further Amendment to Extend the Decision to Renew Joint Funding for 2005

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Exhibit 10.11

SCHERING CORPORATION
2000 Galloping Hill Road        Kenilworth, N.J. 07033

Telephone: (908) 298-4000

Confidential Materials omitted and filed separately with the
Securities and Exchange Commission. Asterisks denote such omissions.

November 30, 2004

Mr. Arthur Hiller
Senior Vice President, Sales & Marketing
Millennium Pharmaceuticals, Inc.
40 Landsdowne Street
Cambridge, Massachusetts 02139-4815

Re:

Additional Field Force Agreement — Further Amendment to Extend the Decision to Renew Joint Funding for 2005

Dear Mr. Hiller:

        I am writing with regard to the Addendum, effective June 1, 2003, to the 1995 Collaboration Agreement among Millennium Pharmaceuticals, Inc., Schering Corporation and Schering-Plough, Ltd., including as such Addendum was previously amended (the "Additional Field Force Agreement").

        As you are aware, Schering and Millennium previously agreed to extend until [**] the deadline for a decision by the JSC on whether or not to continue joint funding of the Additional Field Force for the 2005 calendar year. In order to ensure that the parties reach a fully informed decision that reflects the best interests of both companies and the product, Schering is willing to agree to a further extension of the deadline until the JSC meeting scheduled for December 6, 2004, as follows.

        Any capitalized terms that are not expressly defined herein shall have the meaning set forth in the Additional Field Force Agreement.

        The parties hereby agree to t