Impact of the number of prior chemotherapy regimens on outcomes for patients with metastatic breast cancer treated with eribulin: A post hoc pooled analysis.

Javier Cortes,Chris Twelves

doi:10.1111/tbj.13686

Abstract

In a pivotal phase 3 study (Study 305), eribulin mesylate improved overall survival (OS) in patients with previously treated metastatic breast cancer (MBC) compared with treatment of physician's choice (TPC). This post hoc, pooled subgroup analysis of two phase 3 studies (Study 305 and Study 301) reports the influence of the number of prior chemotherapy regimens (0‐6) on OS in patients with locally advanced/MBC randomized to eribulin versus TPC/capecitabine. Patients with ≤ 3 prior chemotherapies for locally advanced/MBC had longer median OS with eribulin (15.3 months) versus control (13.2 months; hazard ratio, 0.858; P = .01).

Highlights

Metastatic breast cancer (MBC) remains incurable, and few cytotoxic agents prolong overall survival (OS)
An exploratory comparative analysis of OS grouped by ≤3 versus >3 prior treatments, and by individual number of prior lines of treatment, for locally advanced/MBC was completed using data pooled from both studies except as noted
This exploratory subgroup analysis of EMBRACE5 and Study 3016 shows that the OS benefit conferred by eribulin over treatment of physician's choice (TPC)/capecitabine is predominantly seen in patients who had fewer prior regimens (≤3) for locally advanced/MBC with a median OS benefit of 2.1 months

Summary

| BACKGROUND

Metastatic breast cancer (MBC) remains incurable, and few cytotoxic agents prolong overall survival (OS). Open-label, phase 3 trials (Study 305/EMBRACE and Study 301 [ClinicalTrials.gov: NCT00388726 and NCT00337103, respectively]) assessed the efficacy and safety of eribulin in pretreated patients with locally recurrent/MBC.[5,6] In a previous pooled analysis of these 2 studies,[7] median OS was 15.2 months (eribulin) versus 12.8 months (control arm: hazard ratio [HR], 0.85; 95% confidence interval [CI] 0.77-0.95; P = .003); OS favored eribulin in all analyzed subgroups including human epidermal growth factor receptor 2 (HER2)-negative disease (HR, 0.82; P = .002), and triple-negative disease (HR, 0.74; P = .006) These findings were supported by another pooled analysis in patients with ≥1 prior chemotherapy regimens.[8] Here, we report an exploratory, post hoc, pooled subgroup analysis of the influence of the number of prior chemotherapy regimens on OS using data from EMBRACE and Study 301

| METHODS

| DISCUSSION

Findings

| CONCLUSIONS