News

CAMBRIDGE, Mass., May 14, 2001 /PRNewswire/ -- ImmunoGen, Inc. (Nasdaq: IMGN) today announced safety and pharmacokinetic data from 37 patients enrolled in the first human clinical trial of its Tumor-Activated Prodrug (TAP), huC242-DM1/SB-408075, for the treatment of colorectal, pancreatic, and certain non-small-cell lung cancers. In addition, evidence of antitumor activity in several patients was reported.

SB-408075 is a TAP created by conjugating the cytotoxic maytansinoid drug, DM1, with the humanized monoclonal antibody huC242. ImmunoGen has an agreement with GlaxoSmithKline (GSK) to develop and commercialize huC242-DM1/SB-408075.

The results presented yesterday at the 2001 Annual Meeting of American Society of Clinical Oncology in San Francisco demonstrated a dose at which the TAP (SB-408075), is well-tolerated when given as a single bolus every three weeks. Further, no evidence of immunogenicity was detected.

Two patients demonstrated minor responses (reduction of tumor size by approximately one-third) and four additional patients had persistent stable disease for greater than three months. A total of nine patients showed decreases in carcinoembryonic antigen (CEA) levels. CEA is used by physicians to follow the course of colon cancer, to monitor the effect of treatment, and to detect recurrence.

The dose-escalating Phase I/II study was designed to evaluate the pharmacokinetics, maximum tolerated dose and dose-limiting toxicities of huC242-DM1/SB-408075 when administered as a single infusion once every three weeks. The reported results are from patients with either colorectal (32 patients), pancreatic (4 patients) or non-small-cell lung cancer (1 patient). All patients treated had advanced solid malignancies refractory to standard therapy.

Anthony W. Tolcher, M.D., of the Institute for Drug Development of the Cancer Therapy and Research Center (CTRC), San Antonio, Texas, Co-principal Investigator of the study commented on the presentation, "Results of this clinical trial are very promising. This TAP is well-tolerated with side effects that are reversible and easily managed. Further, there have been early signs of activity that are very encouraging."

On-going Clinical Trials for huC242-DM1/SB-408075
Another Phase I/II human clinical study, designed to evaluate the safety of huC242-DM1/SB-408075 when administered on a weekly regimen, is ongoing at the University of Chicago Research Center, under the direction of Richard L. Schilsky, M.D. On May 1, 2001, ImmunoGen and GSK began enrollment in a third Phase I/II human clinical study with huC242-DM1/SB-408075 in a more dose- intensive regimen. This study is being conducted by Anthony W. Tolcher, M.D. and Eric K. Rowinsky, M.D. Both of these studies are designed to test the safety and tolerability of the drug on a more frequent dosing schedule.

Mitchel Sayare, Chairman & CEO of ImmunoGen, Inc., commented, "With the tolerability profile seen in the first study, we can now increase the frequency of drug administration to patients. GlaxoSmithKline continues to proceed on schedule with its clinical development plan."

TAP Technology
ImmunoGen developed its Tumor-Activated Prodrug or TAP technology to address the therapeutic need for improved cancer therapies by delivering highly potent cytotoxic agents directly to tumor cells with minimal harm to healthy tissue. Each TAP product is comprised of a highly potent small molecule effector drug, which is 100- to 1000-fold more potent than existing chemotherapeutics, conjugated to a tumor-targeting monoclonal antibody. The TAPs are designed to act as prodrugs and remain nontoxic while circulating in the body, only activated once they are inside the target cell. In preclinical studies, TAPs have shown therapeutic efficacy and complete cures at doses with no clinical signs of toxicity. [RVJ Chari et al., Proceedings of AACR, 39:4382 (1998)]

About ImmunoGen, Inc.
ImmunoGen, Inc. develops innovative biopharmaceuticals, primarily for cancer treatment. The Company has created potent TAPs, consisting of drugs coupled to monoclonal antibodies for delivery to and destruction of cancer cells. The Company has collaborative arrangements with GlaxoSmithKline, Genentech Inc., Abgenix Inc., British Biotech plc, MorphoSys AG, Avalon Pharmaceuticals, Inc., Raven Biotechnologies and Millennium Pharmaceuticals, Inc.

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 payers; and the uncertainties as to the extent of future government regulation of the pharmaceutical business.