Mitoxantrone as first-line chemotherapy in advanced breast cancer: results of a collaborative European study.

Mitoxantrone (Novantrone; dihydroxyanthracenedione) is a substituted anthraquinone with a spectrum of activity similar to doxorubicin in experimental tumors. One hundred and seventy three patients with advanced breast cancer and no prior cytotoxic therapy for advanced disease entered a phase II study of mitoxantrone, 14 mg/m2 i.v. repeated every 3 weeks. At the time of this analysis 116 patients were evaluable. Eight patients achieved a complete response and 27 a partial response, the overall response rate being 30% (95% confidence limits: 22-39%). The median time until response was recorded was 15 weeks. The median duration of response was 74+ weeks and the median time to progression or death for all 116 patients was 22+ weeks. Mitoxantrone was well tolerated with myelosuppression as the dose-limiting toxicity. The most frequent non-haematological toxicities were nausea and vomiting (65%) but they were rarely severe. Total alopecia occurred in only 6% of the patients. Four patients developed clinically significant evidence of cardiotoxicity after cumulative mitoxantrone doses of 174-256 mg/m2. Thus, mitoxantrone offers comparable efficacy and less acute toxicity than the most active single agents currently available in the treatment of advanced breast cancer.