News

WALTHAM, Mass.--(BUSINESS WIRE)--July 7, 2008--ImmunoGen, Inc. (Nasdaq: IMGN) today announced the start of patient dosing in a Phase I clinical trial evaluating the Company's IMGN388 targeted anticancer compound for the treatment of solid tumors. IMGN388 uses ImmunoGen's Tumor-Activated Prodrug (TAP) technology with an antibody that binds to an integrin target. ImmunoGen submitted the Investigational New Drug (IND) application for IMGN388 to the US Food and Drug Administration in mid-May 2008 and gained authorization to initiate clinical testing in mid-June 2008.

"We believe IMGN388 offers significant promise for the treatment of solid tumors, as the target for this compound is found on many types of solid tumors and also on endothelial cells in the process of forming new blood vessels," commented John Lambert, PhD, Senior Vice President and Chief Scientific Officer. "IMGN388 can actually attack tumors in two ways - by attaching to cancerous cells that express its target and killing them directly and by disrupting the formation of the new blood vessels that every type of solid tumor needs in order to grow. Thus, the potential opportunity for IMGN388 extends beyond tumors that express its integrin target to an even broader pool of solid tumors."

IMGN388 consists of the Company's DM4 cell-killing agent attached to an antibody that binds specifically to an integrin expressed on a wide range of solid tumors - melanomas, sarcomas and many carcinomas, including lung, bladder, renal cell and thyroid carcinomas.

The Phase I trial (Study 201) underway at South Texas Accelerated Research Therapeutics (START) in San Antonio, TX is designed to assess the tolerability and pharmacokinetics of IMGN388 in patients with solid tumors; efficacy information also will be obtained. Increasing doses of the compound, administered every three weeks, are to be evaluated in new cohorts of patients with solid tumors until the maximum tolerated dose (MTD) is established and the dose-limiting toxicities are identified. Once the MTD is established, enrollment will be limited to patients with tumors that are melanomas, sarcomas or those carcinomas that characteristically express the relevant integrin target.

About ImmunoGen, Inc.

ImmunoGen, Inc. develops targeted anticancer therapeutics using its expertise in cancer biology, monoclonal antibodies, and the creation and attachment of potent cell-killing agents. ImmunoGen's TAP technology uses monoclonal antibodies to deliver one of the Company's proprietary cell-killing agents specifically to cancer targets. ImmunoGen has three TAP compounds in clinical testing - IMGN901, IMGN242 and IMGN388. Four additional TAP compounds - trastuzumab-DM1, AVE9633, SAR3419 and BIIB015 - are in clinical testing through the Company's collaborations with Genentech, sanofi-aventis (two compounds), and Biogen Idec, respectively, and a fifth compound is at IND stage. Also, the naked antibody, AVE1642, is in clinical testing through the Company's collaboration with sanofi-aventis. Additional compounds are in earlier stages of development.

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 development of novel anticancer compounds, including IMGN388. A review of these risks can be found in ImmunoGen's Annual Report on Form 10-K for the fiscal year ended June 30, 2007 and other reports filed with the Securities and Exchange Commission.

CONTACT:
Investors:
ImmunoGen, Inc.
Carol Hausner, 781-895-0600
Executive Director, Investor Relations and Corporate Communications
info@immunogen.com

Media:
KMorrisPR
Kathryn Morris, 845-635-9828
Kathryn@kmorrispr.com