Results of a phase II study of maytansine in patients with breast carcinoma and melanoma.

During the phase I study of maytansine at our institution, some activity was observed against breast carcinoma and melanoma. A phase II study was thus initiated to more thoroughly investigate the activity of this drug against these two tumors. In 33 evaluable patients with melanoma, no complete or partial responses were observed. Twenty-one evaluable patients with breast cancer were entered and only one response (partial) was seen. The toxicity was similar to that observed in the phase I study and consisted mainly of diarrhea, paresthesias, phlebitis, and flu-like symptoms. Myelosuppression was infrequent and was short-lived when it occurred.