A phase II, multicenter, single-arm trial of eribulin as first-line chemotherapy for HER2-negative locally advanced or metastatic breast cancer

The treatment goals for metastatic breast cancer (MBC) are prolonging survival and improving the quality of life. Eribulin, a non-taxane tubulin inhibitor, demonstrated improved survival in previous studies and also showed mild toxicity when used in late-line therapy for MBC. We conducted a phase II study to investigate the efficacy of eribulin mesylate as the first-line chemotherapy for human epidermal growth factor receptor 2 (HER2)-negative MBC. This was a phase II, open-label, single-arm, multicenter trial conducted in Japan. Patients with HER2-negative MBC received intravenous eribulin (1.4 mg/m 2 on days 1 and 8 of each 21-day cycle). The primary efficacy outcome was overall response rate (ORR). Secondary outcomes included time to treatment failure, progression-free survival (PFS), overall survival (OS), and safety. A total of 35 patients were enrolled and received a median of 8 (range 1–21) cycles of eribulin therapy. ORR and clinical benefit rate were 54.3 and 62.9 %, respectively. Median PFS was 5.8 months and median OS was 35.9 months. Grade 3 or 4 neutropenia was observed in 63 % of patients. The majority of non-hematological adverse events were mild in severity. The present trial demonstrated that eribulin has antitumor activity comparable with other key established cytotoxic agents with acceptable safety and tolerability. Thus, eribulin as first-line chemotherapy might be beneficial for patients with HER2-negative MBC.