Phase II, Multicenter, Single-Arm, Feasibility Study of Eribulin Combined With Capecitabine for Adjuvant Treatment in Estrogen Receptor-Positive, Early-Stage Breast Cancer

Background: The present phase II, open-label, multicenter study explored the feasibility, safety, and tolerability of eribulin, a novel non-taxane microtubule inhibitor, plus capecitabine as adjuvant therapy.

Patients and methods: Postmenopausal women with early-stage, human epidermal growth factor receptor 2 (HER2)-negative, estrogen-receptor (ER)-positive breast cancer received four 21-day cycles of treatment with eribulin mesylate (1.4 mg/m(2) intravenously on days 1 and 8 of each cycle) combined with capecitabine (900 mg/m(2) orally twice daily on days 1-14 of each cycle [standard schedule] or 1500 mg orally twice daily using a 7-days on/7-days off schedule [weekly schedule]). Feasibility was determined by the relative dose intensity (RDI) of the combination using prespecified criteria for 80% of patients achieving an RDI of ≥ 85%, with a lower 95% confidence boundary > 70%.

Results: The mean RDI was 90.6%, and the feasibility rate was 81.3% among women (n = 67, mean age, 61.3 years) receiving the standard schedule and 95.6% and 100% among women (n = 10, mean age 62.3 years) receiving the weekly schedule. Dose reductions, missed doses, and withdrawals due to adverse events (most commonly hand-foot syndrome) ascribed to capecitabine led to a higher RDI (93.5% vs. 87.8%) and feasibility rate (82.8% vs. 71.9%) for eribulin than for capecitabine using the standard dosing schedule. The most common adverse events were alopecia and fatigue.

Conclusion: Eribulin plus capecitabine with standard or weekly dosing schedules is feasible in patients with early-stage, HER2-negative, ER-positive breast cancer. Full-dose eribulin (1.4 mg/m(2) on days 1 and 8) with capecitabine (1500 mg orally twice daily, 7 days on/7 days off) is recommended as a regimen for further evaluation.