ImmunoGen, Inc. (IMGN), a biopharmaceutical company that develops targeted anticancer therapeutics, today announced that the Company has appointed James J. O’Leary, MD, as Vice President and Chief Medical Officer. Dr. O’Leary will lead the clinical development of ImmunoGen’s product candidates.

“Jim has all of the skills to effectively lead the development of our clinical-stage compounds and provide strategic input on our earlier-stage programs,” commented Daniel Junius, President and Chief Operating Officer. “He has experience in all phases of product development – from preclinical to registration – and in clinical drug development for major international markets as well as for the US. We’re particularly pleased that Jim’s background includes experience at the FDA as well as at leading healthcare companies.”

Prior to joining ImmunoGen, Dr. O’Leary was Senior Medical Director, Clinical Oncology at Bayer Corporation, where his responsibilities included leading the global clinical development team for a late-stage anticancer agent. Before joining Bayer in 2006, he was Medical Director, Clinical Oncology at Pfizer Inc. While at Pfizer, Dr. O’Leary led early clinical development teams for two anticancer agents and, later, the global clinical development team for a more advanced compound. Prior to joining Pfizer as Associate Medical Director in 2000, Dr. O’Leary held the position of Medical Reviewer, Division of Oncology Drug Products, at the US Food and Drug Administration (FDA) and was the lead reviewer on Taxol® (paclitaxel) for adjuvant use in the treatment of breast cancer. Dr. O’Leary completed his post-doctoral training in Internal Medicine at Winthrop University Hospital, his Hematology/Oncology fellowship at New York University Medical Center, and was a Sessions Physician at Bellevue Hospital in the Breast and the Oncology Clinics in New York. He earned his medical degree from the State University of New York – Health Science Center at Brooklyn in 1990.

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. The Company’s Tumor-Activated Prodrug (TAP) technology uses antibodies to deliver one of ImmunoGen’s proprietary cell-killing agents specifically to cancer targets. In addition to the Company’s proprietary clinical pipeline, ImmunoGen collaborators Genentech, sanofi-aventis, Biogen Idec, and Biotest also are testing TAP compounds in the clinic, and the naked antibody AVE1642 is in clinical trials through the Company’s collaboration with sanofi-aventis. Other ImmunoGen collaborative partners include Bayer HealthCare and Amgen.

Taxol® is a registered trademark of Bristol-Myers Squibb Company.