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): October 17, 2007

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):

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

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

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

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

ITEM 8.01 OTHER EVENTS

On October 17, 2007, ImmunoGen, Inc. (Nasdaq: IMGN), issued a press release to announce that sanofi-aventis has advanced the Tumor-Activated Prodrug (TAP) compound, SAR3419, into Phase I clinical testing. This event triggers a $1 million milestone payment to ImmunoGen. SAR3419 is a potential new treatment for non-Hodgkin’s lymphoma and other B-cell malignancies, and was created by ImmunoGen and licensed to sanofi-aventis as part of a broader collaboration between the companies.

A copy of the press release is attached hereto as Exhibit 99.1 and is incorporated by reference in this Item 8.01.

ITEM 9.01. FINANCIAL STATEMENTS AND EXHIBITS

(d) The following exhibit is being filed herewith:

Exhibit No.		Exhibit
99.1		Press Release of ImmunoGen, Inc. dated October 17, 2007

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.
		(Registrant)

Date: October 17, 2007		/s/ Daniel M. Junius

		Daniel M. Junius
		Executive Vice President and Chief Financial Officer

EXHIBIT INDEX

Exhibit No.		Exhibit
99.1		Press Release of ImmunoGen, Inc. dated October 17, 2007