Phase 2 study of single-agent IV vinflunine as third-line treatment of metastatic breast cancer after failure of anthracycline-/taxane-based chemotherapy

A multicenter, open-label, phase 2 study evaluated the efficacy and safety of intravenous vinflunine as third-line treatment in patients with progressing metastatic breast cancer (MBC) after failure of anthracycline- and taxane-based chemotherapy. Fifty-six patients with MBC, relapsing after receiving 2 previous treatments for advanced disease, including both anthracyclines and taxanes, received 320 mg/m(2) of vinflunine once every 3 weeks (median number of 2.5 cycles, range: 1-13). According to an independent radiologist, the response rate was 12.5% (95% CI: 5.2-24.1) and 14% (95% CI: 5.3-27.9) (6 partial responses) in the treated and evaluable populations, respectively. Disease control was achieved in 42.9% and 51.2% of the patients, respectively. Median progression-free survival was 2.6 months (95% CI: 1.6-4.0 months) with a median overall survival of 11.4 months (95% CI: 7.4-14.2 months). Duration of response was 6.8 months (95% CI: 5.6 months, upper limit not reached). Leukopenia was the most frequent hematologic toxicity, with grade 3/4 severity in 49.1% of the patients. Grade 3 neutropenia in 30.9%, grade 4 in 40.0% of patients, febrile neutropenia (5.4%), and 1 case of neutropenia infection (1.8%) were reported. Other grade 3 toxicities included anemia (5.5%), fatigue (14.3%), and constipation (7.1%), which were noncumulative. The adverse events associated with vinflunine were predictable and manageable. Vinflunine is an active and well-tolerated agent as third-line treatment of patients with MBC after failure of anthracycline- and taxane-based therapy. These results warrant further investigation of vinflunine monotherapy or in combination for the treatment of MBC.