8-K

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d)

OF THE SECURITIES EXCHANGE ACT OF 1934

Date of Report (Date of earliest event reported): March 27, 2006

ImmunoGen, Inc.

(Exact name of registrant as specified in its charter)

Massachusetts	0-17999	04-2726691
(State or other jurisdiction of incorporation)	(Commission File Number)	(IRS Employer Identification No.)

128 Sidney Street, Cambridge, MA 02139

(Address of principal executive offices) (Zip Code)

Registrant's telephone number, including area code: (617) 995-2500

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

oWritten communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

oSoliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

oPre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

oPre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

ITEM 1.01 - AMENDMENT OF A MATERIAL DEFINITIVE AGREEMENT

On March 27, 2006, ImmunoGen, Inc. (NASDAQ: IMGN) and Millennium Pharmaceuticals, Inc. (NASDAQ: MLNM) agreed to amend the Access, Option and License Agreement (the Agreement) executed by the parties on March 30, 2001. The amendment extends the Access Term, as defined in the Agreement, for an additional year, which ends March 30, 2007. In consideration for this extension, Millennium will pay to ImmunoGen an extension fee equal to two hundred and fifty thousand dollars ($250,000).

A copy of the press release is attached to this current report on Form 8-K as Exhibit 99.1.

ITEM 9.01. FINANCIAL STATEMENTS AND EXHIBITS

Exhibit No.	Exhibit
99.1	Press Release of ImmunoGen, Inc. dated March 30, 2006

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SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

	ImmunoGen, Inc.
Date: March 30, 2006	By:	/s/ Karleen M. Oberton
		Senior Corporate Controller (Principal Accounting Officer)

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EX-99.1

Exhibit 99.1

128 Sidney Street, Cambridge, MA 02139-4239             < font id="TAB2" style="LETTER-SPACING: 9pt">    TEL: (617) 995-250    FAX: (617) 995-2510

Contacts:

Investors Carol Hausner Executive Director, Investor Relations and Corporate Communications Tel: (617) 995-2500 info@immunogen.com Media Tony Loke Rx Communications Group, LLC Tel: (917) 322-2164 tloke@rxir.com

For Immediate Release

ImmunoGen, Inc. Announces Extension of Technology Access Agreement

by Millennium Pharmaceuticals, Inc.

CAMBRIDGE, MA, March 30, 2006 - ImmunoGen, Inc. (Nasdaq: IMGN) today announced that Millennium Pharmaceuticals, Inc. has extended the agreement that provides Millennium with certain rights to test ImmunoGen’s Tumor-Activated Prodrug (TAP) technology with antibodies to specific targets and to license the right to use the technology to develop products on the terms defined in the agreement. This agreement was scheduled to expire March 30, 2006 unless extended by Millennium. It is now scheduled to expire March 30, 2007.

About ImmunoGen, Inc.

ImmunoGen, Inc. develops targeted anticancer biopharmaceuticals. The Company’s proprietary TAP technology uses tumor-targeting antibodies to deliver a potent cell-killing agent specifically to cancer cells. Three TAP compounds are in clinical testing - huN901-DM1 and huC242-DM4, which are wholly owned by ImmunoGen, and AVE9633, which is in development by the sanofi-aventis Group. A fourth TAP compound, trastuzumab-DM1 in development by Genentech, now has an effective IND. Genentech, Centocor (a wholly-owned subsidiary of Johnson & Johnson), Biogen Idec, the sanofi-aventis Group, Millennium Pharmaceuticals, Inc., Boehringer Ingelheim, and Abgenix have licensed the right to develop and/or test TAP compounds to specific targets; ImmunoGen also has a broader collaboration with the sanofi-aventis Group.

This press release includes forward-looking statements. For these statements, ImmunoGen claims the protection of the safe harbor for forward-looking statements provided by the Private Securities Litigation Reform Act of 1995. It should be noted that there are risks and uncertainties related to the Company’s development of its own products, as well as to the development of products by our collaborators. A review of these risks can be found in ImmunoGen’s Annual Report on Form 10-K for the fiscal year ended June 30, 2005 and other reports filed with the Securities and Exchange Commission.

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