Vinflunine: a new active drug for second-line treatment of advanced breast cancer. Results of a phase II and pharmacokinetic study in patients progressing after first-line anthracycline/taxane-based chemotherapy

To evaluate the single agent activity, pharmacokinetics and tolerability of the novel tubulin targeted agent vinflunine (VFL) (320 mg m(-2) q 21 days) as second-line chemotherapy in patients with metastatic breast carcinoma (MBC). All patients had disease progression after anthracycline/taxane (A/T) therapy. They could have received a nonanthracycline adjuvant treatment and subsequently received a first-line A/T combination for advanced/metastatic disease; or relapsed 46 months after completion of adjuvant A/T therapy and were subsequently treated with the alternative agent; or relapsed within 6 months from an adjuvant A/T combination. Objective response was documented in 18 of 60 patients enrolled (RR: 30% (95% confidence interval (CI): 18.9-43.2%)). Among the responders, seven patients had relapsed during a period of < 3 months from taxane-based regimen yielding a RR of 33.3%. The median duration of response was 4.8 months (95% CI: 4.2-7.2), median progression-free survival was 3.7 months (95% CI: 2.8-4.2) and median overall survival was 14.3 months (95% CI: 9.2-19.6). The most frequent adverse event was neutropenia (grade 3 in 28.3% and grade 4 in 36.7% of patients). No febrile neutropenia was observed. Fatigue (grade 3 in 16.7% of patients) and constipation (grade 3 in 11.7% of patients) were also common; these were non-cumulative and manageable permitting achievement of a good relative dose intensity of 93.5%. Vinflunine is an active agent with acceptable tolerance in the management of MBC patients previously treated with (A/T)-based regimens. These encouraging phase II results warrant further investigation of this novel agent in combination with other active agents in this setting or in earlier stages of disease.