News

CAMBRIDGE, Mass., May 21, 2002 /PRNewswire-FirstCall via COMTEX/ -- ImmunoGen, Inc. (Nasdaq: IMGN) today announced the presentation of data at the 2002 Annual Meeting of the American Society of Clinical Oncology from Phase I studies conducted with cantuzumab mertansine (huC242-DM1/SB-408075) at the Institute for Drug Development, Cancer Therapy and Research Center (CTRC) in San Antonio, Texas. The principal investigators in the studies are Eric K. Rowinsky, M.D., and Anthony W. Tolcher, M.D.

The two studies examined different dosing regimens. In the first study (referred to as the "Part A Trial" in the poster), a single infusion of cantuzumab mertansine was given once per three weeks; in the second study (the "Part B Trial"), cantuzumab mertansine was administered thrice weekly for three weeks followed by a rest week. The Part A Trial, which is completed, included 37 patients - 32 with colorectal cancer, 4 with pancreatic cancer, and 1 with non-small-cell lung cancer. The Part B Trial, which is still underway, includes 18 patients to date - 12 with colorectal cancer, 3 with non-small-cell lung cancer and 3 with other cancer types. The patients had failed, on average, three prior chemotherapy regimens, with all patients failing at least one prior chemotherapy regimen. Half of the patients had also failed radiation therapy.

The poster notes that the key objectives of this Phase I research were to determine the maximum tolerated dose (MTD) and the dose-limiting toxicities (DLT) for the dosing regimens. It was also designed to characterize product pharmacokinetics, toxicities, and their inter-relationship. Also documented are any preliminary indications of product anti-tumor activity.

Findings

Maximum Tolerated Dose - In the Part A Trial, an MTD of 235 mg/m2/dose was established for the once-per-three-week dosing regimen. The lowest dose studied was 22 mg/m2/dose; the highest was 295 mg/m2/dose. The poster notes that, while the Part B Trial is not completed, and thus the MTD is not finalized, the MTD appears to be 45 mg/m2/dose. The lowest dose studied was 30 mg/m2 thrice weekly; the highest has been 60 mg/m2 thrice weekly.

Dose Limiting Toxicity - The principal DLT was found to be reversible transaminitis. This was found to occur primarily in patients with bulky liver metastases.

Eric K. Rowinsky, M.D., Director of Clinical Research at the Institute for Drug Development, CTRC and Brooke Army Medical Center, said, "These Phase I studies demonstrate that cantuzumab mertansine is very well tolerated on multiple schedules in heavily pretreated patients. The preliminary evidence of anti-tumor activity in refractory patients is also encouraging, warranting further evaluations of the agent in multiple types of malignancies."

John M. Lambert, Ph.D., Senior Vice President, Pharmaceutical Development, ImmunoGen, Inc., commented, "We are pleased with the tolerability profile seen to date with cantuzumab mertansine. The findings from the Phase I studies support continued clinical development of this product candidate."

While no data related to biologic activity in the on-going study were presented, indications of anti-tumor activity reported previously include reductions in the carcinoembryonic antigen (CEA) tumor marker and evidence of disease regression in several heavily pretreated patients.

About Cantuzumab Mertansine

Cantuzumab mertansine is a Tumor-Activated Prodrug (TAP) created by conjugating the cytotoxic agent DM1 with the humanized monoclonal antibody C242. The antibody targets the CanAg receptor found on a number of cancer types, including colorectal, pancreatic, gastric, and non-small-cell lung cancers. ImmunoGen has an agreement with GlaxoSmithKline that enables GlaxoSmithKline to develop and commercialize this product candidate in exchange for milestone payments and royalties on net product sales.

About ImmunoGen, Inc.

ImmunoGen, Inc. develops innovative biopharmaceuticals for the treatment of cancer. The Company's TAP technology couples highly potent cytotoxic agents with tumor-targeting antibodies to create effective new treatments for cancer with minimal damage to normal tissue. Two TAP products developed by ImmunoGen are in clinical trials - cantuzumab mertansine and huN901-DM1/BB-10901; the latter is licensed to British Biotech in certain territories. Several companies are advancing TAP products comprised of ImmunoGen's TAP technology and the partner's antibody - Genentech (Trastuzumab-DM1), Millennium (MLN591DM1) and Boehringer Ingelheim (bivatuzumab mertansine). ImmunoGen also has multi-target agreements with Genentech, Abgenix, and Millennium that can potentially yield multiple additional TAP products.

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; the uncertainties as to the extent of future government regulation of the pharmaceutical business; and other factors described in ImmunoGen's periodic filings with the Securities and Exchange Commission.

SOURCE ImmunoGen, Inc.

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