ImmunoGen Inc announced that British Biotech is starting the Phase II portion of the Phase I/II study being conducted in the United States with huN901-DM1 (BB-10901), a monoclonal antibody-based chemotherapy agent designed for the treatment of small-cell lung cancer (SCLC).

In the Phase I portion of this study, the maximum tolerated dose was found to be 60 mg/m2 when huN901-DM1 was administered once weekly for four weeks followed by two weeks off treatment. At this dose level and below, toxicities were modest (in particular, no hematologic toxicity was observed) and preliminary evidence of antitumor activity was noted. These findings were presented recently at the "Molecular Targets and Cancer Therapeutics" symposium organized by the European Organization for Research and Treatment of Cancer (EORTC), the National Cancer Institute (NCI), and the American Association for Cancer Research (AACR).

The Phase II portion of this study will provide an initial evaluation of the efficacy of the 60 mg/m2 dose of huN901-DM1 when administered with this same weekly dosing schedule to patients with relapsed SCLC. The information gained will be used in conjunction with the findings from the Phase I study now underway in the United Kingdom to determine the dosing schedule to be used in anticipated future trials with this product candidate. huN901-DM1 is administered on a more frequent basis in the U.K. study.

huN901-DM1 is a conjugate of the cytotoxic maytansinoid drug, DM1, with the humanized monoclonal antibody, huN901. The drug is designed to selectively kill certain types of cancer cells including those found in small-cell lung cancer tumors. British Biotech acquired rights to develop and commercialise huN901-DM1 for Europe and Japan under an agreement with ImmunoGen in May 2000. ImmunoGen retained commercialization rights for the U.S. and the rest of the world.