Phase II clinical trial of ixabepilone (BMS-247550), an epothilone B analog, as first-line therapy in patients with metastatic breast cancer previously treated with anthracycline chemotherapy

Purpose: There is a need for new agents to treat metastatic breast cancer (MBC) in patients for whom anthracycline therapy has failed or is contraindicated. This study was conducted to assess the efficacy and safety of the novel antineoplastic, the epothilone B analog ixabepilone, in patients with MBC previously treated with an adjuvant anthracycline. Patients and Methods: Patients were age ≥ 18 years and had received a prior anthracycline-based regimen as adjuvant treatment. Ixabepilone as first-line metastatic chemotherapy was administered as a 40 mg/m² intravenous infusion during 3 hours every 3 weeks. The primary efficacy end point was objective response rate (ORR). Secondary efficacy end points included duration of response, time to response, time to progression, and survival. Results: All 65 patients were assessable for response. Their median age was 52 years (range, 33 to 80 years). ORR was 41.5% (95% CI, 29.4% to 54.4%), median duration of response was 8.2 months (95% CI, 5.7 to 10.2 months), and median time to response was 6 weeks (range, 5 to 17 weeks). Median survival was 22.0 months (95% CI, 15.6 to 27.0 months). Treatment-related adverse events were manageable and mostly grades 1/2: the most common of these (other than alopecia) was mild to moderate neuropathy, which was primarily sensory and mostly reversible in nature. Conclusion: Ixabepilone is efficacious and has a predictable and manageable safety profile in women with MBC previously treated with an adjuvant anthracycline.