A phase I-II study of continuous 5-day infusion mitomycin-C.

A phase I-II study was undertaken to establish the maximum-tolerated dose of a continuous 5-day infusion of mitomycin-C and its efficacy in patients with advanced metastatic drug-resistant breast and gastrointestinal malignancies. The dose-limiting toxicity was myelosuppression, predominantly thrombocytopenia, and was severe and cumulative. Nonhematologic toxicity was infrequent, and no renal or cardiac toxicity was seen. For patients with breast cancer who had received extensive prior therapy, 3 mg/m2/day for 5 days repeated every 6-8 weeks were well-tolerated doses; and for patients with gastrointestinal cancer, the maximum-tolerated dose was 4 mg/m2/day. One patient with breast cancer had a partial response lasting 4 months, and no responses were observed in patients with gastrointestinal cancer. The administration of mitomycin-C by continuous infusion did not appear to have improved its therapeutic index.