Mitomycin C and mitoxantrone in anthracycline-pretreated advanced breast cancer patients. A phase II study.

Twenty-one patients with anthracycline-pretreated advanced breast cancer were treated with mitomycin C plus mitoxantrone (MM), 10 mg/m2, on day 1 of a 28-day cycle. All patients were evaluated for toxicity and response. Overall, 83 cycles were administered, with a median number of 4 cycles per patient. Hematologic toxicity, not requiring hospitalization, was the major side effect. Vomiting occurred in 19.2% of cycles. Objective response rate was 33.3% (95% confidence interval: 12.2-53.1%); best responses were 1 complete and 6 partial; also 7 stable and 7 progressive disease were recorded. The best responding site was the viscera, the worst was bone. Responses were seen preferentially in second- rather than in third-line therapy and in patients who had responded to previous chemotherapy, although differences were not statistically significant. Kaplan-Meier estimated median time to progression and overall survival were 26 weeks (range: 2-67 weeks) and 35 weeks (range: 6-79 weeks), respectively. In conclusion the MM regimen showed acceptable toxicity and appreciable activity in anthracycline-pretreated advanced breast cancer.