BACKGROUND Paclitaxel plus gemcitabine (PG) combination chemotherapy is a preferred chemotherapeutic regimen for patients with metastatic breast cancer (MBC). Eribulin mesylate is a halichondrin non-taxane inhibitor of microtubule dynamics. A recent pooled analysis with eribulin showed improved overall survival (OS) in various MBC patient subgroups pretreated with anthracycline and taxane. Furthermore, eribulin may have less neurotoxicity than paclitaxel.

PATIENTS AND METHODS This study was a prospective randomised phase II, open-label, two-arm, multicentre study comparing eribulin plus gemcitabine (EG) with PG chemotherapy as a first-line treatment for patients with human epidermal growth factor receptor 2-negative MBC. We hypothesised that EG chemotherapy would not be inferior to PG chemotherapy. The primary end-point was progression-free survival (PFS), which was estimated to be 70% at 6 months for each arm. The secondary end-points were as follows: OS, neuropathic scale, toxicity and clinical benefit rate.

RESULTS A total of 118 patients (median age: 50, 24-66) were enrolled between March 2015 and March 2016 and were randomly assigned to PG (n = 59) or EG (n = 59) chemotherapy. The mean number of metastatic sites was 3 (range 1-8). The 6-month PFS rates for both arms were 72% for EG and 73% for PG (P = 0.457). There was no significant difference in OS between the two groups (not reached versus 21.2 months, P = 0.2234). The median number of chemotherapy cycles for both groups was 10 for EG and 8 for PG (range 2-32). Clinical benefit rates were 44% for EG and 49% for PG. Major toxicities were neutropenia and neurotoxicity. Grade II or above neurotoxicity was more common with PG than with EG (13.6% for EG versus 45.8% for PG, P < 0.0001).

CONCLUSION EG chemotherapy had similar clinical benefits to PG chemotherapy in terms of PFS but less neurotoxicity.

TRIAL REGISTRATION KCSG BR13-11; ClinicalTrials.gov, NCT02263495.