News

CAMBRIDGE, Mass., Jan 4, 2002 /PRNewswire via COMTEX/

ImmunoGen, Inc. (Nasdaq: IMGN) today announced that the U.S. Patent and Trademark Office has issued the Company U.S. Patent 6,333,410 B1, which covers the preparation and purification of thiol-containing maytansinoids, such as DM1. DM1 is the lead small molecule effector drug used in the Company's Tumor-Activated Prodrug (TAP) technology.

"An important part of our corporate strategy is to consider all of the steps necessary to turn our innovative TAP technology into significant commercial products," said Mitchel Sayare, Ph.D., Chairman and CEO of ImmunoGen, Inc. "Our development of a patent-protected method of DM1 production is consistent with this strategy."

ImmunoGen's TAP technology is designed to deliver a highly potent cell- killing agent, such as DM1, specifically to cancer cells with minimal harm to healthy tissue. Each TAP product is comprised of the cytotoxic effector molecules bound to a selective, cancer-targeting monoclonal antibody. The antibody delivers the effector molecules specifically to the targeted cancer. Once the TAP product has bound to the cancer cell, it is internalized into the cell, the effector molecules are released and the cancer cell is killed.

"This patent provides ImmunoGen with another level of protection on our DM1 technology," said Walter Blattler, Ph.D., Executive Vice President, Science and Technology, ImmunoGen, Inc. "DM1 is now patent protected not only on its composition and use, but now also by means of production."

About ImmunoGen, Inc.

ImmunoGen, Inc. develops innovative biopharmaceuticals, primarily for cancer treatment. The Company has created potent tumor-activated prodrugs, consisting of drugs coupled to monoclonal antibodies, for delivery to and destruction of cancer cells. The Company has partnerships with GlaxoSmithKline, Genentech, British Biotech, Abgenix, Millennium, Boehringer Ingelheim, MorphoSys, Avalon Pharmaceuticals and Raven Biotechnologies. Two TAP products are currently in clinical trials, with additional products expected to start trials in 2002.

This press release includes forward-looking statements based on management's current expectations. Factors that could cause future results to differ materially from such expectations include, but are not limited to: the success of the Company's research strategy; the applicability of the discoveries made therein; the difficulties inherent in the development of pharmaceuticals, including uncertainties as to the timing and results of preclinical studies; delayed achievements of milestones; reliance on collaborators; uncertainty as to whether the Company's potential products will succeed in entering human clinical trials and uncertainty as to the results of such trials; uncertainty as to whether adequate reimbursement for these products will exist from the government, private healthcare insurers and third-party payors; and the uncertainties as to the extent of future government regulation of the pharmaceutical business.

Contacts:

ImmunoGen, Inc.

Investors
Carol Hausner
Senior Director, Investor Relations and Corporate Communications
Tel: (617) 995-2500
info@immunogen.com

Media
Pete Holmberg
Rx Communications Group, LLC
Tel: (917) 501-7434
pholmberg@rxir.com

SOURCE ImmunoGen, Inc.