Randomized phase II study of nab‐paclitaxel as first‐line chemotherapy in patients with HER2‐negative metastatic breast cancer

Weekly administration of nanoparticle albumin‐bound paclitaxel (nab‐paclitaxel) has been shown to be a safe and effective treatment for metastatic breast cancer (MBC) in clinical studies. We conducted a multicenter, randomized, open‐label phase II study to compare the efficacy and safety of weekly nab‐paclitaxel and docetaxel in Japanese patients with human epidermal growth factor receptor 2‐negative MBC. The primary endpoint was progression‐free survival (PFS). Patients were randomized to receive nab‐paclitaxel (150 mg/m(2) nab‐paclitaxel once per week for 3 of 4 weeks; n = 100) or docetaxel (75 mg/m(2) docetaxel every 3 weeks; n = 100). The median PFS by independent radiologist assessment was 9.8 months (90% confidence interval [CI]: 8.5–11.2) for nab‐paclitaxel and 11.2 months (90% CI: 8.4–13.8) for docetaxel (hazard ratio: 1.25, P = 0.363), and the median overall survival was 42.4 months and 34.0 months, respectively. The overall response rate was 56.1% for nab‐paclitaxel and 52.5% for docetaxel. Adverse events in both treatment arms were similar to previous reports. Neutropenia was the most common adverse event in both arms, with 35.0% of patients in the nab‐paclitaxel arm and 89.0% in the docetaxel arm experiencing grade 4 neutropenia. Grade 3 peripheral sensory neuropathy occurred in 22.0% of patients in the nab‐paclitaxel and 5.0% in the docetaxel arm. In this study, although weekly nab‐paclitaxel 150 mg/m(2) did not show superiority in PFS compared with docetaxel, efficacy outcomes were similar in patients treated with weekly nab‐paclitaxel and docetaxel.