News

CAMBRIDGE, Mass.--(BUSINESS WIRE)--Jan. 8, 2004--ImmunoGen, Inc. (Nasdaq: IMGN)

-- ImmunoGen to Advance Cantuzumab Mertansine into Phase II

Testing and Regain Control of huN901-DM1 from Vernalis

ImmunoGen, Inc. (Nasdaq: IMGN), a biotechnology company that develops targeted anticancer products, announced today that the Company will advance both of its clinical stage Tumor-Activated Prodrug (TAP) compounds - cantuzumab mertansine and huN901-DM1 - into proof-of-concept trials managed by ImmunoGen.

ImmunoGen will advance cantuzumab mertansine into Phase II proof-of-concept studies. Previously, the Company had indicated its intention to advance the compound into the next stages of clinical testing with a partner. ImmunoGen's collaboration with Aventis has enabled the Company to retain the rights to cantuzumab mertansine and advance the compound into Phase II testing on its own.

Additionally, ImmunoGen will take over future development of huN901-DM1 from Vernalis (formerly British Biotech). Vernalis will continue the two huN901-DM1 clinical studies currently underway, but has now relinquished its rights to the product. ImmunoGen is preparing to initiate its own clinical trial with huN901-DM1 in the United States.

Mitchel Sayare, Ph.D., Chairman and CEO, commented, "Both of these compounds have the potential to become significant anticancer products. Now that we have the partnership with Aventis in place - and the funding it provides - we can advance these compounds into well-designed proof-of-concept studies. This decision will have little impact on our burn rate over the next six months, but is expected to result in some increase in our burn rate in our fiscal year ending June 30, 2005."

ImmunoGen's TAP technology uses a tumor-targeting antibody to deliver a highly potent cell-killing agent specifically to cancer cells. In addition to cantuzumab mertansine and huN901-DM1, two partner-developed TAP compounds have advanced into clinical testing.

Cantuzumab Mertansine

ImmunoGen developed cantuzumab mertansine for the treatment of cancers that express CanAg, such as colon, pancreatic, gastric, other abdominal cancers, and many non-small-cell lung cancers. Cantuzumab mertansine is composed of ImmunoGen's huC242 antibody, to target the compound to CanAg-positive cancer cells, and DM1, to kill the targeted cancer cells. ImmunoGen developed the potent cell-killing agent DM1 specifically for antibody-guided delivery to cancer cells.

In Phase I studies cantuzumab mertansine was found to be well tolerated, evidence of anticancer activity was reported, and essential dosing information was obtained. The next step is for the compound to be evaluated in patients with specific types of CanAg-expressing cancers in Phase II trials. Initiation of cantuzumab mertansine proof-of-concept trials requires production of clinical materials. Due to the time required for the various steps in the production process (e.g., antibody production and release; release of final conjugated product), patient dosing is expected to begin in 12 to 18 months. During this time, ImmunoGen will finalize its study plans, reconfirm that the compound's formulation is optimized, and complete protocol development and study center preparation.

huN901-DM1

huN901-DM1 is composed of ImmunoGen's huN901 antibody, which targets CD56, and DM1. This compound was developed by ImmunoGen for the treatment of CD56-expressing cancers such as small-cell lung cancer and cancers of neuroendocrine origin. CD56 also is expressed in multiple myeloma and acute myeloid leukemia malignancies.

In May 2000 ImmunoGen licensed to British Biotech the rights to develop and commercialize huN901-DM1 for Europe and Japan; British Biotech also was responsible for developing the product for marketing approval in the U.S. In 2003, British Biotech merged with RiboTargets, Ltd. and the combined entity subsequently merged with Vernalis Group plc to become Vernalis plc. As a result of these changes, ImmunoGen and Vernalis have renegotiated their agreement on huN901-DM1. ImmunoGen will take over future development of the compound. Vernalis, which has agreed to relinquish its rights to the product, will complete the U.K. Phase I clinical study of huN901-DM1 currently underway and will continue the U.S. Phase I/II study until June 30, 2004. If the U.S. Phase I/II study is not completed as of that date, ImmunoGen will assume responsibility for it.

ImmunoGen is preparing to initiate its own huN901-DM1 proof-of-concept study in the U.S. The Company intends to study the compound in CD56-expressing hematologic malignancies (multiple myeloma and/or acute myeloid leukemia) as strong interest has been expressed by clinicians to test the compound in these cancers. Study initiation is expected in 2004.

About ImmunoGen, Inc.

ImmunoGen, Inc. develops targeted anticancer therapeutics. The Company's proprietary TAP technology uses tumor-targeting antibodies to deliver a potent cell-killing agent specifically to cancer cells. Two ImmunoGen-developed TAP products have begun clinical evaluation: cantuzumab mertansine and huN901-DM1. ImmunoGen out-licenses its TAP technology in exchange for upfront, milestone, and manufacturing payments plus royalties. Companies developing products using ImmunoGen's TAP technology include Boehringer Ingelheim (bivatuzumab mertansine), Millennium Pharmaceuticals (MLN2704), and Genentech (Trastuzumab-DM1); ImmunoGen also has multitarget agreements with Genentech, Abgenix, and Millennium. In July 2003, ImmunoGen and Aventis announced a collaboration to discover, develop, and commercialize antibody-based anticancer therapeutics. The agreement provides ImmunoGen with committed funding and also includes milestone payments, royalties, and co-promotion rights.

This press release includes forward-looking statements based on management's current expectations. 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 the Company'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 success of the Company's research and clinical development processes; the difficulties inherent in the development of pharmaceuticals, including uncertainties as to the timing, expense and results of preclinical studies and clinical trials; the Company's dependence upon existing and potential collaborative partners; uncertainty as to whether the Company's potential products or those of the Company's collaborators will succeed in entering human clinical trials and uncertainty as to the results of such trials; the risk that the Company and/or its collaborators may not be able to obtain regulatory approvals necessary to commercialize their product candidates; the potential development by competitors of competing products and technologies; uncertainty whether the Company's TAP technology will produce safe, effective and commercially viable products; and other factors more fully described in ImmunoGen's Annual Report on Form 10-K for the fiscal year ended June 30, 2003 and other current reports filed with the Securities and Exchange Commission.

CONTACT: Investors:
ImmunoGen, Inc.
Carol Hausner, 617-995-2500
info@immunogen.com
or
Media:
Rx Communications Group, LLC
Pete Holmberg, 917-322-2164
pholmberg@rxir.com

SOURCE: ImmunoGen, Inc.