A phase II, multicenter, single-arm study of tri-weekly low-dose nanoparticle albumin-bound paclitaxel chemotherapy for patients with metastatic or recurrent breast cancer

Background Nanoparticle albumin-bound (nab)-paclitaxel is a solvent-free formulation of paclitaxel that is bound to albumin and has demonstrated improved progression free survival in previous studies of breast cancer. However, it is difficult to treat Japanese patients with metastatic or recurrent breast cancer with the recommended dose of 260 mg/m(2) of (nab)-paclitaxel for more than six cycles due to the occurrence of adverse events. To evaluate the treatment continuity and safety of low-dose nab-paclitaxel, we conducted a phase II study of nab-paclitaxel in patients with metastatic or recurrent breast cancer who had received up to one prior chemotherapy. Patients and methods Treatment included low doses of 180 mg/m(2) nab-paclitaxel that were administered on day 1 of each 3-week cycle to 35 patients. The primary endpoint was the completion rate of six cycles of treatment. Results A total of 35 eligible patients were enrolled and received a median of eight (range 2-24) cycles of low-dose nab-paclitaxel therapy. The completion rate of six cycles of treatment was 66%. ORR and clinical benefit rate was 23 and 71%, respectively. Median PFS was 6.5 months and median OS was 44 months. Adverse events were relatively mild. Commonly observed grade 3/4 adverse events were neutropenia (46%), leukopenia (9%), and hypertension (3%). No grade 3-4 peripheral sensory neuropathy occurred. Conclusion Treatment with a low dose of nab-paclitaxel once every 3 weeks was tolerable and of acceptable safety and might be beneficial for patients with metastatic or recurrent breast cancer.