BACKGROUND: Bendamustine, a bifunctional alkylating agent with anticipated purin-like properties is active in metastatic breast cancer (MBC) patients. This multicenter phase II trial defines the toxicity and activity of bendamustine in heavily pretreated patients. PATIENTS AND METHODS: Fifty-one patients were included. Patients had a median number of 2 prior chemotherapeutic regimens for MBC (range 0-7) consisting of anthracyclines and taxanes: 26 patients (51%); anthracyclines: nine patients (17.6%); taxanes: seven patients (13.7%); others: five patients (9.8%). Bendamustine was administered four weekly at a dose of 120 mg/m(2) on days 1 and 2. RESULTS: Fifty patients were assessable. Of total, 200 courses were administered. We observed no complete response (CR); 10 patients [20%; 95% confidence interval (CI): 10.0% to 33.7%] achieved a partial response (PR), 14 patients (28%) remained stable for at least 6 months resulting in a clinical benefit rate (CR + PR + stable disease) of 48% (95% CI: 33.7%to 52.6%). Median time to progression was 3.4 months (range 1-51.1). The median duration of remission was 6.6 months (range 1.8-48.7). The treatment was well tolerated with mainly hematologic toxic effects. CONCLUSION: Single-agent bendamustine is an active treatment in patients with MBC independent of the previous treatment. The low toxicity profile favors its use as a single agent.
