Eribulin efficacy in long responder patients with metastatic breast cancer: A multicentric observational study

Eribulin can represent a therapeutic alternative for patients with advanced breast cancer who have received at least one or two lines of anthracyclines-based chemotherapy and taxane therapy. In this observational study, we focused on long-responder patients, i.e. with an objective response or stability ≥ 6 months under eribulin to better characterize them.

Metastatic breast cancer (MBC) patients treated by eribulin in 2nd, 3rd or 4th line between September 2011 and June-2018 were included. The following parameters were assessed: primary tumor and metastasis characteristics, type of response and duration, disease progression, treatment received, toxicities, progression free survival (PFS), overall survival (OS), and prognostic factors of OS and PFS. Special attention was paid to patients with hepatic disease (HD).

Among the 98 patients included, an analysis was conducted on 84 patients (median age 62). Median duration of response was 25.6 weeks (95 IC 22-27.7) with a median number of infusions of 6. Response was similar, irrespective of ERI line number. HD was observed in 70.2 % of patients. Median PFS was 9 months (95 %CI 8-10). Subgroup analysis showed similar PFS, irrespective of HD (p = 0.21) and treatment line (p = 0.46). Median OS was 24 months. (95 % IC 20-31). The main prognostic factors of OS were duration of response (p < 0.001) and, progesterone receptor positiveness was associated to PFS (p = 0.006).

This multicentric, retrospective study highlights eribulin as a potential second-line therapy for MBC with a median response duration of 25 weeks after 6 infusions. The safety and efficacy profiles align with previous studies, supporting its role as a viable treatment option. Notably, the response and PFS were independent of hepatic metastasis, suggesting benefit across various MBC subtypes, including those with liver involvement. However, the retrospective design warrants cautious interpretation, and further prospective studies are needed to confirm these findings and optimize eribulin's use, potentially through molecular profiling for personalized treatment strategies.