A phase II, multicenter, single-arm trial of eribulin as first- or second-line chemotherapy for HER2-negative advanced or metastatic breast cancer: evaluation of efficacy, safety, and patient-reported outcomes.

PURPOSE: Although eribulin is a suitable option for early-line treatment of metastatic breast cancer (MBC), data on first- or second-line use of eribulin for human epidermal growth factor receptor 2 (HER2)-negative MBC are still limited. Therefore, we conducted a phase II trial to investigate the efficacy and safety of eribulin for first- or second-line chemotherapy for HER2-negative MBC.

MATERIALS AND METHODS: We performed a phase II, open-label, single-arm, multicenter study in Japan. Eligible patients were women with histologically confirmed HER2-negative MBC without chemotherapy or only one chemotherapy line for MBC. The primary endpoint was the overall response rate (ORR) and the secondary endpoints included the clinical benefit rate (ORR + stable disease for 6 months; CBR), progression-free survival (PFS), overall survival (OS), duration of response (DOR), safety, and health-related quality of life (HRQoL).

RESULTS: A total of 35 patients with HER2-negative MBC were enrolled between March 2013 and February 2017 (data cut-off July 31, 2017). The ORR was 37.1% (95% CI 21.1-53.2%). The CBR was 54.3% (95% CI 37.8-70.8%). The median PFS was 6.2 months (95% CI 2.7-9.4 months) and median OS was 21.4 months (95% CI 11.5-32.9 months). Common grade 3/4 adverse events were neutropenia (42.9%) but febrile neutropenia (2.9%). Although the majority of non-hematological adverse events were mild in severity, one patient died of pneumonitis. In HRQoL analysis, eribulin appeared to maintain HRQoL of many patients.

CONCLUSIONS: Eribulin as first- or second-line chemotherapy is effective and has manageable toxicity for patients with HER2-negative MBC.