Real-world analysis of eribulin in metastatic breast cancer (MBC): An assessment of time to treatment failure (TTF) in a community oncology setting.

174 Background: There have been important advances in the treatment of patients with MBC. However, certain patient subgroups such as whose who are triple negative remain a therapeutic challenge. Eribulin is the newest cytotoxic to gain regulatory approval for MBC in the Unites States. In this analysis, the safety and efficacy of eribulin in TNBC patients and those with prior anthracycline exposure were assessed in an early cohort treated in a U.S. community oncology setting. Methods: Ninety patients treated in eight community oncology clinics across the U.S. were identified. Patients were followed from the first cycle of eribulin until disease progression, discontinuation due to toxicity, or death. Data collection included baseline patient and disease characteristics, prior and subsequent anticancer therapy, use of supportive care drugs, number and type of dose limiting toxicity, delivered dose intensity, duration of eribulin therapy and time to treatment failure (TTF). Results: Eribulin was administered after a median of three prior lines of chemotherapy (range 0 to 15). The drug was delivered as a single agent in 79 of 90 patients (88%) at the clinically approved dosage of 1.4 mg/m2on days 1 and 8 of a 21 day cycle. Patients received a median of 4 cycles (1 to 16) for an overall mean duration of 2.9 months (0 to 14.2 months). Approximately 17 of 90 patients (18.9%) were identified as triple negative and 57 of 90 (63.3%) had received prior anthracycline treatment. The median TTF (inter quartile range) was 4 mon (2.3 to 5.6) in all patients. There were no significant differences in TTF by triple negative status (HR=0.1.22, p = 0.49) and prior exposure to anthracyclines (HR=0.78, p = 0.15). In all patients, the most common dose limiting toxicities were neutropenia (32%), anemia (31%), neuropathy (21%) and febrile neutropenia (8.9%). These events led to the premature discontinuation of eribulin in 8 of 90 patients (8.9%). Conclusions: TTF with eribulin was comparable regardless of triple negative status and prior exposure to anthracyclines. These findings are consistent with results from previous clinical studies and warrant further real-world analyses in a larger population.