ImmunoGen, Inc. Announces Updated Guidance for 2011 Fiscal Year

ImmunoGen, Inc. (Nasdaq: IMGN), a biotechnology company that develops targeted antibody-based anticancer products, today announced updated guidance for the Company’s fiscal year ending June 30, 2011.

Net cash used in operations is expected to be between $0 and $4 million, with a net loss expected to total between $60 and $64 million. Cash and marketable securities at its fiscal year end of June 30, 2011 are expected to total between $106 and $110 million, which should be sufficient to fund operations through the Company’s 2013 fiscal year.

About ImmunoGen, Inc.

ImmunoGen, Inc. develops targeted anticancer therapeutics using the Company’s expertise in tumor biology, monoclonal antibodies and potent cancer-cell killing agents. The Company’s TAP technology uses monoclonal antibodies to deliver one of ImmunoGen’s proprietary cancer-cell killing agents specifically to tumor cells. There are currently seven TAP compounds in the clinic, with a wealth of clinical data reported with the technology. ImmunoGen collaborative partners include Amgen, Bayer Schering Pharma, Biogen Idec, Biotest, Genentech (a member of the Roche Group), Novartis, and sanofi-aventis. The most advanced compound using ImmunoGen’s TAP technology, T-DM1, is in Phase III testing through the Company’s collaboration with Genentech. More information about ImmunoGen can be found at www.immunogen.com.

This press release includes forward-looking statements based on management's current expectations. These statements include, but are not limited to, ImmunoGen's expectations related to: the Company's net loss, cash used in operations and capital expenditures in its 2011 fiscal year; its cash and marketable securities as of June 30, 2011; and the Company’s cash sufficiency through its 2013 fiscal year. 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. Various factors could cause ImmunoGen's actual results to differ materially from those discussed or implied in the forward-looking statements, and you are cautioned not to place undue reliance on these forward-looking statements, which are current only as of the date of this release. Factors that could cause future results to differ materially from such expectations include, but are not limited to: the difficulties inherent in the development of novel pharmaceuticals, including uncertainties as to the timing, expense and results of preclinical studies, clinical trials and regulatory processes; ImmunoGen's ability to financially support its product programs; ImmunoGen's dependence on collaborative partners; industry merger and acquisition activity; and other factors more fully described in ImmunoGen's Annual Report on Form 10-K for the fiscal year ended June 30, 2010 and other reports filed with the Securities and Exchange Commission.