Dose-finding study of docetaxel and doxorubicin in first-line treatment of patients with metastatic breast cancer

Abstract

To determine the maximum tolerated dose (MTD), the dose-limiting toxicity (DLT) and the recommended dose of docetaxel in combination with doxorubicin, and to evaluate the activity in patients with advanced breast cancer. Forty-two women with untreated metastatic breast cancer (79% with visceral metastases; 52% with prior adjuvant anthracycline therapy) were treated with doxorubicin (40-60 mg/m2) i.v. bolus followed one hour later by docetaxel (50-85 mg/m2) one-hour i.v. infusion every three weeks, without G-CSF support. The MTD occurred at the dose level combining 85 mg/m2 of docetaxel and 50 mg/m2 of doxorubicin, with the DLT being neutropenic sepsis. Neutropenia and/or its complications were manageable and no grade 3-4 or severe non-hematological toxicities were observed. Fluid retention was frequent but never severe. With a median cumulative dose of doxorubicin of 392 mg/m2 (240-559 mg/m2) and a median follow-up time of 29 months (9(+)-41), no congestive heart failure was observed. High activity was observed at all dose levels, particularly the last four, with a response rate of 81% (95% confidence interval (95% CI): 62.5-92.5). Median time to progression was 46 weeks (6(+)-62). Two-year survival was 66%, and median survival has not yet been reached. Docetaxel-doxorubicin is feasible, safe and highly active. The incidence of febrile neutropenia without G-CSF requires careful monitoring but is acceptable in this setting. There does not appear to be an increase in the cardiac toxicity of doxorubicin. The recommended doses is either docetaxel 75 mg/m2 and doxorubicin 50 mg/m2 or docetaxel 60 mg/m2 and doxorubicin 60 mg/m2, administered every three weeks.