Efficacy of eribulin in patients with metastatic breast cancer (MBC): a pooled analysis by HER2 and ER status
Eribulin has been assessed in two phase 3, open-label trials in patients with locally recurrent or MBC progressing after an anthracycline and taxane. Eribulin significantly increased overall survival (OS) compared with treatment of physician's choice (TPC) in one study and showed a non-significant trend for improved OS vs capecitabine in the other. We present an unplanned pooled analysis of these data.
In the EMBRACE trial, women had received 2–5 lines of chemotherapy for advanced disease. In this ?3rd line setting, patients were randomized 2:1 to eribulin mesylate (1.4mg/m2 iv on days 1 and 8 every 21 days) or TPC. In study 301, patients who had received 0–2 prior chemotherapies for advanced disease were randomized 1:1 to eribulin (as above) or capecitabine (1.25 g/m2 orally b.i.d. days 1–14 every 21 days). We analysed OS (based on survival curve adjusted by study) by 2-sided stratified log-rank tests and Cox regression in the overall intent-to-treat population and in the HER2–, triple negative (TNBC) and HER2+ subgroups. Between-treatment analyses were stratified by region, prior capecitabine use and study (plus HER2 status [overall group] and TNBC [HER2– group]).
1864 patients (median age 54yrs) were included, most had been treated in the 2nd (31.5%) or 3rd line (32.7%) MBC settings. Eribulin provided significantly improved OS vs control overall (15.2 vs 12.8 months, HR=0.85, 95%CI=0.77,0.95, p=0.003), and in HER2– (15.2 vs 12.3 months, HR=0.82, 95%CI=0.72,0.93, p=0.002) and TNBC (12.9 vs 8.2 months, HR=0.74, 95%CI=0.60,0.92, p=0.006) patients, but not HER2+ patients (13.5 vs 12.2 months, HR=0.82, 95%CI=0.62,1.06, p=0.135). As reported before, the eribulin safety profile was similar in the studies.
Eribulin significantly improved OS vs standard therapies in MBC patients with HER2– and TNBC; in patients with HER2+ disease the difference did not reach statistical significance but numbers were smaller.
We would like to gratefully acknowledge Theo Giannopoulos and Susanne Booth at Castle Hill Hospital for their help in acquiring ovarian tissue samples, and Jane Smales for coordinating the clinical aspects of the study. This study is funded by a grant from NC3Rs (Registry File: G1100600).
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