Eribulin, trastuzumab, and pertuzumab as first-line therapy for patients with HER2-positive metastatic breast cancer: a phase II, multicenter, collaborative, open-label, single-arm clinical trial

Purpose To examine the efficacy and safety of triple therapy with eribulin, trastuzumab, and pertuzumab in patients with HER2-positive metastatic breast cancer (MBC) who never received any prior therapy in the first-line metastatic/advanced setting. Methods Eribulin 1.4mg/m(2) (days 1 and 8), trastuzumab 8mg/kg over 90min and 6mg/kg over 30min, and pertuzumab 840mg/body over 60min and 420mg/body over 30min were administered intravenously in 21-daycycles. Results 25 women (median age, 57years [range, 41-75years]) received a median of 10cycles (range, 0-34cycles); 24 had performance status (PS) 0, 1 PS 1, 8 stage IV breast cancer, and 17 recurrence. Lung and liver metastases occurred in 9 and 9 patients, respectively. Median time to treatment failure with eribulin was 9.1months (95% confidence interval [CI], 4.3-13.9months), and median progression-free survival was 23.1months (95% CI, 14.4-31.8months). The overall response rate (complete response [CR]+partial response [PR]) was 80.0% (95% CI, 59.3-93.2%), and the clinical benefit rate (CR+PR+stable disease 24weeks) was 84.0% (95% CI, 63.9-95.5%). The most common treatment-emergent adverse events (TEAEs) were alopecia (92.0%), fatigue (68.0%), and sensory peripheral neuropathy (60.0%). Grade 3/4 TEAEs occurred in 11 patients (44.0%). The only grade 4 TEAE was neutrophil count decreased (16.0%). Neither grade 4 peripheral neuropathy nor febrile neutropenia occurred. Conclusions ETP therapy showed acceptable efficacy and safety and is a potential first-line therapy for patients with HER2-positive MBC.