ImmunoGen, Inc. Announces Presentation Of HuN901-DM1; Clinical Activity Reported Includes Sustained Complete Remission And Stable Disease

ImmunoGen, Inc. (Nasdaq: IMGN) today announced the presentation of encouraging clinical findings with the Company's huN901-DM1 Tumor-Activated Prodrug (TAP) compound at the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics underway in Philadelphia, PA. As reported today, clinical activity seen with huN901-DM1 in this study includes a complete remission lasting at least 15 weeks and stable disease lasting up to 18 weeks. Today's poster presentation (#B97) features the first data to be reported from this on-going Phase I clinical trial evaluating huN901-DM1 when administered daily for three consecutive days in a 21-day cycle to patients with CD56-expressing solid tumors. In this dose-escalation study, new cohorts of patients receive progressively higher doses of huN901-DM1 until the maximum tolerated dose is established. All study patients have relapsed or refractory small-cell lung cancer (SCLC) or other CD56-expressing solid tumors. HuN901-DM1 is the only anticancer agent administered. A sustained complete remission was reported with one of the four patients treated at a dose level of 36 mg/m2/day (108 mg/m2 over three consecutive days) or higher for which response information is available. This patient was diagnosed with Merkel cell cancer in late 2003, underwent surgery, radiation therapy, and chemotherapy, but her cancer had reappeared by late 2004. After commencing treatment with huN901-DM1 through this study, she has been in complete remission for at least 15 weeks. Stable disease lasting 6 to 18 weeks was reported in an additional five patients. Response information was available for twenty-one patients at the time of the poster presentation, inclusive of patients receiving the lowest dose levels tested. To date, five dose levels - 4, 8, 16, 24, and 36 mg/m2/day - have been assessed without establishing the maximum tolerated dose, and evaluation of 48 mg/m2/day is underway. HuN901-DM1 has been generally well tolerated. Four individuals had serious adverse events that were considered to be at least possibly drug-related (one patient each): fatigue, constipation, pancreatitis, and hypotension plus myocardial infarction. No clinically significant myelosuppression or serious infusion reactions were reported, nor was thyroid or adrenal dysfunction reported.