Phase II study of mitoxantrone, leucovorin, and infusional fluorouracil for treatment of metastatic breast cancer.

A new combination of mitoxantrone, folinic acid (leucovorin), and infusional fluorouracil (5-FU) was administered to 57 previously treated patients with metastatic breast cancer to evaluate the response rate, response duration, and toxicity of this regimen. Fifty-three patients who received 313 courses of therapy were assessable for response and toxicity. Median age was 48 years (range, 33 to 80 years), and the patients had received an average of 1.5 chemotherapy regimens before this study. Of 53 assessable patients, 24 (45%, or 42% of all entered patients) experienced partial responses (PRs) with a median duration of 6 months (range, 2 to 13 months). Nine (69%) of 13 assessable patients without prior doxorubicin treatment responded, compared with 15 (38%) of 40 with prior doxorubicin (P less than .05). Toxicity was generally mild with dose reductions necessitated more often by mucositis and/or diarrhea than by myelosuppression. One patient with prior high-dose doxorubicin treatment developed congestive heart failure. The combination of mitoxantrone, leucovorin, and infusional 5-FU is an active and well-tolerated regimen for metastatic breast cancer and deserves further evaluation in patients without prior doxorubicin therapy.