Eribulin monotherapy improved survivals in patients with ER-positive HER2-negative metastatic breast cancer in the real world: a single institutional review

Despite being routinely prescribed worldwide for several years, data regarding the safety, efficacy, and survival benefit of eribulin in clinical settings for the treatment of metastatic breast cancer (MBC) are limited. This retrospective observational study investigated the survival benefit of eribulin compared with conventional chemotherapy regimens in Japanese women with MBC. Women with estrogen receptor (ER)-positive human epidermal growth factor receptor 2 (HER2)-negative (ER+/HER2−) MBC, including unresectable locally advanced breast cancer, treated at a single institution were included in this study. The primary efficacy measure assessed overall survival (OS), and safety was evaluated as the number of grade 3 and 4 adverse events. Of the 293 patients analyzed, 66 received eribulin (eribulin arm) and 227 received conventional chemotherapeutic agents excluding eribulin (noneribulin arm). The median OS from MBC diagnosis in the eribulin arm was 72.1 months (95 % CI 13.3–168.3) compared with 43.3 months (95 % CI 9.1–202.0) in the noneribulin arm [hazard ratio (HR): 0.67, 95 % CI 0.47–0.96; P = 0.025]. No significant differences were noted in OS between eribulin used as a first-/second-line or third-/>third-line treatment for MBC. No patient discontinued eribulin therapy due to AEs. In the eribulin arm, grade 4 neutropenia and grade 3 febrile neutropenia were observed in 8 (12.1 %) and 4 (6.1 %) patients, respectively. Eribulin therapy has a survival benefit in Japanese women with ER+/HER2− MBC in routine clinical practice, with no unexpected grade 3/4 AEs. Interestingly, eribulin might be beneficial as any line therapy for ER+/HER2− MBC.