Mitoxantrone in advanced breast cancer: a phase II trial of the Southwest Oncology Group

124 patients with metastatic breast cancer were entered into this phase II trial of mitoxantrone (DHAD). Patients were stratified prior to treatment as good or poor risk, and whether they had received previous therapy with an anthracycline derivative. Mitoxantrone was given every 21 days at a starting dose of 12 mg/m2 for good risk patients and 10 mg/m2 for poor risk patients. Among the group who had not received anthracyclines, 12 are fully or partially evaluable for response with five classified as good risk. One complete response, ongoing at 52 weeks was seen in this group. Of the seven poor risk patients, stable disease was seen in two. 103 patients with prior anthracycline exposure are fully or partially evaluable, 31 good risk and 72 poor risk. There were three partial responses in each group. Toxicity was primarily myelosuppression, and was more severe in the poor risk group. Mitoxantrone when used on this schedule has minimal activity among heavily pretreated patients with metastatic breast cancer.