Eribulin Mesylate in Pretreated Breast Cancer Patients: A Multicenter Retrospective Observational Study

Background: Eribulin was recently approved in patients progressing after being treated with anthracyclines and taxanes and after two or more chemotherapy lines for advanced disease. Objectives: This multicenter observational retrospective study was performed in order to evaluate activity and tolerability of eribulin in real-world patient population. Methods: 133 advanced breast cancer patients pretreated with ≥ 2 chemotherapy lines for metastatic disease were retrospectively enrolled in the observational trial in 11 italian cancer centres. Results: A median of 5 cycles of eribulin (range, 1-15) were administered. Twenty-eight partial responses were observed, for an overall response rate of 21.1% (95%CI,14.1-28.0). A stable disease was recorded in 57 patients (42.8%), and a clinical benefit (response or stable disease lasting ≥ six months) was observed in 51 patients (38.3%, 95%CI, 30.1-46.6). The subgroup analysis showed that a significant improvement in term of partial response and clinical benefit was achieved when eribulin was administered in HER-2 negative tumors (p=0.01 and p=0.004, respectively) and when it is given as third-line (p=0.09 and p=0.02, respectively). Toxicity was manageable; fatigue is the most common side effect observed, usually of low-grade, and clearly cumulative-dose related. Conclusions: In this retrospective, observational analysis eribulin confirmed its efficacy and manageable tolerability even in real-world population and in heavily pretreated patients.