Phase II Study of Eribulin Mesylate Administered Biweekly in Patients With Human Epidermal Growth Factor...

Patients with human epidermal growth factor receptor-2-negative metastatic breast cancer (MBC), whose disease progressed on prior chemotherapy, have a poor prognosis. Eribulin, a microtubule dynamics inhibitor, extends overall survival in previously treated MBC. The most common adverse event associated with eribulin is neutropenia, which may result in dose interruptions or reductions. A modified biweekly dosing schedule of eribulin was assessed for efficacy as well as improvements in hematologic toxicity.

In this open-label, single-arm, multicenter, phase II study, previously treated (2-5 chemotherapy regimens for metastatic disease) patients with human epidermal growth factor receptor-2-negative MBC received intravenous eribulin 1.4 mg/m² over 2 to 5 minutes on days 1 and 15 of each 28-day cycle. The primary study endpoints were objective response rate (ORR; complete response [CR] + partial responses [PR]) and disease control rate (DCR; CR + PR + stable disease [SD]).

Among 58 treated patients, the ORR was 12% (95% confidence interval [CI], 5%-24%), DCR (CR, n = 1; PR, n = 6; SD, n = 30) was 65%, and the median progression-free survival was 3.6 months (95% CI, 2.9-4.1 months). Grade 3 or 4 neutropenia was 31%; 50% of all patients, and 78% of patients with neutropenia (all grades), received hematopoietic growth-factor support.

The efficacy and safety results obtained with a biweekly eribulin schedule in this phase II trial appear similar to those associated with the approved eribulin schedule (1.4 mg/m² on days 1 and 8 of a 21-day cycle) reported in the EMBRACE study.