Phase II multicenter study of larotaxel (XRP9881), a novel taxoid, in patients with metastatic breast cancer who previously received taxane-based therapy

Background: Treatment options are limited for patients with refractory metastatic breast cancer (MBC). Larotaxel (XRP9881) is a novel taxoid with preclinical activity against taxane-resistant breast cancer. The current phase II trial of larotaxel was conducted in women with taxane-treated MBC. Patients and methods: Patients were stratified by response to prior taxane therapy (resistant or nonresistant). Larotaxel 90 mg/m² was administered as a 1-h infusion every 3 weeks. Patients were evaluated for tumor response every two cycles. A blinded external response review committee determined the overall response rate (ORR), duration of response (DOR), and time to progression (TtP) of the disease. Median survival time (MST) and safety were also evaluated. Results: One hundred and thirty patients were treated. In the nonresistant group, the ORR was 42%; median DOR 5.3 months; median TtP 5.4 months; and MST 22.6 months. In the resistant group, the ORR was 19%; median DOR 5.0 months; median TtP 1.6 months; and MST 9.8 months. The most common grade 3/4 adverse events were neutropenia (82%), fatigue (15%), diarrhea (12%), febrile neutropenia (9%), neutropenic infection (8%), and sensory neuropathy (7%). Conclusions: Larotaxel has good activity, manageable toxicity, and a favorable therapeutic index in women with taxane-pretreated MBC.