Outcome of eribulin as a late treatment line for Thai metastatic breast cancer patients

Background: We report the safety and efficacy of eribulin as a late treatment line in Thai metastatic breast cancer (MBC) patients. Patients and methods: A total of 30 MBC patients treated with eribulin between January 2014 and January 2017 were retrospectively analyzed. The patients were scheduled to receive 1.4 mg/m2 of eribulin on day 1, day 8 and subsequently every 21 days. All patients had previously received at least three chemotherapy regimens including anthracycline and taxane. Response rate and progression-free survival (PFS) were analyzed. Results: The median age was 56 years (range, 40-74 years), with a median follow-up time of 5.7 months (range, 0.2-25 months). The overall response rate was 30% (nine patients): four patients had triple-negative breast cancer, three patients had luminal B breast cancer and two patients had luminal A breast cancer. The median PFS was 2.9 months (range, 0.2-14 months). The median number of previous chemotherapy regimens was 4 (range, 3-9). Univariate analysis showed that the number of regimens (four or fewer) prior to eribulin was statistically associated with superior PFS (P = 0.009). Multivariate analysis also showed similar statistical association between number of prior regimens (four or fewer) and better PFS adjusted by age group (≥50 years; hazard ratio = 1.29; 95% CI: 1.0-1.65; P = 0.046). There were no toxic deaths or grade 4 toxicities. Nine (30%) patients had grade 3 anemia toxicities, and the other common toxicities were leukopenia and neutropenia. Four (13%) patients required dose reduction and 16 (53%) patients required dose delay because of toxicities. Conclusion: Eribulin is an effective drug for heavily pretreated MBC patients with tolerable toxicities. The benefit was superior in patients who received fewer than four previous chemotherapy regimens.