High-dose mitoxantrone in metastatic breast cancer: a phase I-II trial.

Eighteen women with metastatic breast cancer entered a phase I-II study of high-dose mitoxantrone (MXT). They were heavily pretreated (mean, 2.3 prior regimens) with drugs including both doxorubicin (14 patients) and MXT at usual doses (three). Doses studied were 16, 20, 25, and 30 mg/m2, repeated every 3-4 weeks. Marked leukopenia was seen at all dose levels (four episodes of infection were successfully treated). Fatigue and malaise were the most common nonhematologic toxic effects. At 25 mg/m2, six of 13 courses resulted in severe fatigue and malaise. MXT is tolerated at doses up to 25 mg/m2 every 3-4 weeks. Cardiac function must be closely monitored. No responses were seen in these heavily pretreated patients.