Five-day continuous-infusion vinblastine in the treatment of breast cancer.

One hundred six evaluable patients with metastatic breast cancer refractory to prior chemotherapy were treated with 5-day intravenous infusions of vinblastine at 1.4 to 2.0 mg/m2/day, through silastic elastomer permanent central venous catheters. Thirty-nine patients achieved objective responses; 5 were considered complete. The overall response rate of 37% was independent of prior exposure to intermittent intravenous vinca alkaloids or prior response to front-line doxorubicin combination chemotherapy. Objective responses were documented in 48% of the patients who received daily doses above 1.7 mg/m2 and in 32% and 29% of those treated with 1.7 mg/m2 or less, respectively (P = 0.10). Myelosuppression was more severe in responders, who received higher average doses, (median average nadir, 850 granulocytes/mm3) than in nonresponders (median, 1300 granulocytes/mm3), but was always rapidly reversible. Infections related to neutropenia were uncommon. Catheter-related toxicities occurred in 13 of 106 patients. Other toxicities were limited. These results confirm that vinblastine given as a continuous 5-day infusion is one of the most effective agents in the treatment of metastatic breast cancer and suggest that its activity is dose-dependent.