Mitoxantrone for the treatment of advanced breast cancer: single-agent therapy in previously untreated patients.

Mitoxantrone (dihydroxyanthracenedione) is a substituted anthraquinone with a similar spectrum of activity to adriamycin in experimental tumours. One hundred and thirty-four patients with advanced breast cancer and no prior chemotherapy for advanced disease were treated with mitoxantrone (14 mg/m2 i.v. q 3 weeks), of whom 99 are presently evaluable for response and all for toxicity. Six patients achieved a complete response and 29 a partial response, the overall response rate being 35% (95% confidence limits, 25-45%). Median time to treatment failure was greater than 46 weeks. Mitoxantrone was well tolerated, myelosuppression being the dose-limiting toxicity. The most frequent nonhaematological toxicities were nausea and vomiting (40%), but these were rarely severe. Total alopecia occurred in only 6 patients. Four patients developed clinically significant evidence of cardiotoxicity after cumulative mitoxantrone doses of 174-256 mg/m2. Mitoxantrone offers comparable efficacy and less acute toxicity than the most active currently available single agents in advanced breast cancer.