News

MIAMI BEACH, Fla., Nov. 1, 2001 /PRNewswire/ -- ImmunoGen, Inc. (Nasdaq: IMGN) today announced very favorable safety data from the initial 27 patients enrolled in a 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 anti-tumor activity in several patients was reported. These preliminary findings were presented today at the 2001 American Association for Cancer Research -- National Cancer Institute - European Organization for Research and Treatment of Cancer International Conference on Molecular Targets and Cancer Therapeutics (AACR- NCI-EORTC).

The dose-escalating, multi-dose Phase I/II study was designed to characterize the safety and pharmacokinetic profile and determine the maximum tolerated dose and dose-limiting toxicities of huC242-DM1/SB-408075 when administered weekly. These results will help to determine the protocols for broader Phase II clinical trials. The study is being conducted by ImmunoGen's development partner, GlaxoSmithKline, at the University of Chicago Cancer Research Center under the direction of Richard L. Schilsky, M.D. All patients treated had advanced disease refractory to standard therapy. Patients had received a median of two prior chemotherapy regimens. Patients were treated with huC242-DM1/SB-408075 at doses ranging from 40 mg/m2 to 138 mg/m2. The maximum tolerated dose was determined to be 115 mg/m2. Dose-limiting toxicities were fatigue and asymptomatic, reversible elevation of liver enzymes.

"These data add to the excitement that we feel for the potential of this product candidate. It is gratifying that huC242-DM1/SB-408075 is tolerated so well in these very sick patients," commented John M. Lambert, Ph.D., Senior Vice President, Pharmaceutical Development of ImmunoGen, Inc. "A manageable toxicity profile is a critical issue in cancer drug development. Combined with the promising evidence of biological activity seen to date, we are very enthusiastic about the potential for huC242-DM1/SB-408075."

The reported results are from patients with various forms of cancer: colorectal (18 patients), pancreatic (4 patients), unknown primary (3 patients), non-small-cell lung (1 patient) and peritoneal cancer (1 patient). Patient enrollment in the study is continuing to include a total of 48 evaluable patients. Additional patients are being dosed at 115 mg/m2 administered weekly.

Promising evidence of anti-tumor activity was observed. One patient, diagnosed with diffuse peritoneal disease and producing massive ascites, experienced complete resolution of ascites production. It was also observed that this patient had no evidence of disease progression after 42 weeks. A patient with pancreatic cancer had persistent, stable disease for 24 weeks. Another patient with advanced adenocarcinoma of unknown primary origin experienced a 66% reduction in total tumor mass after five weeks of treatment, although the disease eventually progressed.

Another Phase I/II human clinical study, designed to evaluate huC242- DM1/SB-408075 in a more dose-intensive regimen, is ongoing at the Institute for Drug Development of the Cancer Therapy and Research Center (CTRC), San Antonio, Texas. This study is being conducted by Anthony W. Tolcher, M.D. and Eric K. Rowinsky, M.D.

HuC242-DM1/SB-408075 is a TAP created by conjugating the cytotoxic maytansinoid drug, DM1, with the humanized monoclonal antibody C242. ImmunoGen has an agreement with GlaxoSmithKline to develop and commercialize huC242- DM1/SB-408075.

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 being activated once they are inside the target cell. Two TAPs are in human clinical trials.

About ImmunoGen, Inc.

ImmunoGen, Inc. develops innovative biopharmaceuticals, primarily for cancer treatment. The Company has created potent tumor-activated prodrugs, consisting of drugs coupled to monoclonal antibodies for delivery to and destruction of cancer cells. In addition to GlaxoSmithKline, the Company has collaborative arrangements with Genentech, Abgenix, Millennium, British Biotech, MorphoSys, Avalon Pharmaceuticals, and Raven Biotechnologies.

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