Clinical usefulness of eribulin as first- or second-line chemotherapy for recurrent HER2-negative breast cancer: a randomized phase II study (JBCRG-19).

Background: Anthracycline (A) or taxane T-based regimens are the standard early-line chemotherapy for metastatic breast cancer (BC). A previous study has shown a survival benefit of eribulin in heavily pretreated advanced/recurrent BC patients. The present study aimed to compare the benefit of eribulin with treatment of physician's choice (TPC) as first- or second-line chemotherapy for recurrent HER2-negative BC.

Methods: Patients with recurrent HER2-negative BC previously receiving anthracycline and taxane AT-based chemotherapy in the adjuvant or first-line setting were eligible for this open-label, randomized, parallel-group study. Patients were randomized 1:1 by the minimization method to receive either eribulin (1.4 mg/m on day one and eight of each 21-day cycle) or TPC (paclitaxel, docetaxel, nab-paclitaxel or vinorelbine) until disease progression or unacceptable toxicity. The primary endpoint was progression-free survival (PFS). Secondary endpoints included time to treatment failure (TTF), overall response rate (ORR), duration of response, and safety (UMIN000009886).

Results: Between May 2013 and January 2017, 58 patients were randomized, 57 of whom (26 eribulin and 31 TPC) were analyzed for efficacy. The median PFS was 6.6 months with eribulin versus 4.2 months with TPC (hazard ratio: 0.72 [95% confidence interval (CI), 0.40-1.30], p = 0.276). Median TTF was 6.0 months with eribulin versus 3.6 months with TPC (hazard ratio: 0.66 [95% CI, 0.39-1.14], p = 0.136). Other endpoints were also similar between groups. The most common grade ≥ 3 adverse event was neutropenia (22.2% with eribulin versus 16.1% with TPC).

Conclusions: Eribulin seemed to improve PFS or TTF compared with TPC without statistical significance. Further validation studies are needed.