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/m² nab-paclitaxel once per week for 3 of 4 weeks; n = 100) or docetaxel (75 mg/m² 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/m² did not show superiority in PFS compared with docetaxel, efficacy outcomes were similar in patients treated with weekly nab-paclitaxel and docetaxel.