Phase II study of divided-dose vinblastine in advanced breast cancer patients.

The pharmacokinetics of a 5-day, continuous infusion of vinblastine have been reproduced by an i.v. divided bolus at 0 and 48 h [10]; this schedule can be easily applied to outpatients. We treated 26 evaluable patients with refractory, advanced breast cancer with 3.5-4 mg/m2 vinblastine given i.v. by a divided bolus at 0 and 48 h of 21-day cycles. Neurotoxicity and myelosuppression were the main side effects: severe constipation and peripheral neurotoxicity developed in 14% and 3% of the patients, respectively; severe leukopenia and thrombocytopenia occurred in 24% and 10% of the patients, respectively. One partial response, 14 no changes, and 11 progressions were obtained. Our results do not support the use of vinblastine in divided doses in treating this disease.