Efficacy and safety evaluation of eribulin-trastuzumab combination therapy with heavily pretreated HER2-positive metastatic breast cancer

Purpose: Eribulin mesylate is a non-taxane microtubule inhibitor which is a synthetic holichondrin B analog that can be used after anthracycline and taxane treatment in patients with metastatic breast cancer. We aimed to analyze the results of eribulin-trastuzumab combination in aggressively pretreated metastatic HER2-positive breast cancer patients. Methods: In this single-center study, the records of 36 patients with HER-2-positive metastatic breast cancer who received at least one cycle of eribulin-trastuzumab in our clinic between 2015 and 2018 were analyzed retrospectively. Kaplan-Meier survival analysis was used for progressionfree survival (PFS), and overall survival (OS) analyzes. Two-sided p values <0.05 were considered statistically significant. Results: A total of 36 patients with metastatic breast cancer were eligible and included in this study. The median age of the patients was 41 years (range 20-60). Most patients were heavily pretreated with a median of 5 (range 3-8) previous chemotherapy lines before eribulin. At the end of the follow up period (February 2018) all patients received a median of 5.5 cycles of eribulin-trastuzumab. Partial response (PR) was achieved in 9 patients (25%) and stable disease (SD) in 17 patients (47%). Median PFS was 4 months (95% CI: 3.8-6.1), and median OS was 10 months (95% CI: 7.5-12.4). The most common adverse events were grade 1-2 anemia (n=12, 33%), neutropenia (n=12, 33%) and grade 3-4 neuropathy (n=4, 11.1%). Conclusion: Eribulin-trastuzumab combination is an effective and safe treatment option with a low toxicity profile for aggressively pre-treated patients with metastatic breast cancer.