Mitchel Sayare, Ph.D.
Chairman, President and
Chief Executive Officer,
ImmunoGen, Inc.

Walter A. Blättler, Ph.D.
Executive Vice President,
Science and Technology,
ImmunoGen, Inc.

David W. Carter
Chairman and Chief Executive Officer,
Xenogen Corporation

Michael R. Eisenson
Managing Director and
Chief Executive Officer,
Charlesbank Capital Partners, LLC

Stuart F. Feiner
Executive Vice President,
General Counsel and Secretary,
Inco Limited

Mark Skaletsky
Chairman and Chief Executive Officer,
Essential Therapeutics, Inc.

Mitchel Sayare, Ph.D.
President and Chief Executive Officer

Gregg D. Beloff
Vice President,
Finance and Chief Financial Officer

Walter A. Blättler, Ph.D.
Executive Vice President,
Science and Technology

John M. Lambert, Ph.D.
Senior Vice President,
Pharmaceutical Development

Virginia Lavery
Vice President,
Senior Controller and Treasurer

Pauline Jen Ryan
Vice President,
Business Development

ImmunoGen, Inc.
128 Sidney Street
Cambridge, Massachusetts 02139
(617) 995-2500
www.immunogen.com

Tuesday, November 11, 2003
At the Offices of the Company
128 Sidney Street
Cambridge, Massachusetts 02139

Mellon Investor Services LLC
85 Challenger Road
Ridgefield Park, New Jersey 07660
(201) 329-8660
(800) 288-9541
www.melloninvestor.com

Mintz, Levin, Cohn, Ferris, Glovsky and
Popeo, P.C.
Boston, Massachusetts

Ernst & Young LLP
Boston, Massachusetts