Pembrolizumab vs Investigator-Choice Chemotherapy for Metastatic Triple-Negative Breast Cancer
In this large, international, phase III trial, patients with progressive metastatic triple-negative breast cancer were randomized to receive pembrolizumab or investigator’s choice of single-agent chemotherapy in the second- or third-line setting. Median overall survival was 9.9 months with pembrolizumab versus 10.8 months with chemotherapy. Survival remained similar between treatment groups in the prespecified analyses evaluating patients with PD-L1 combined positive score (CPS) of ≥10 or ≥1. However, post hoc exploratory analysis of patients with CPS ≥20 suggested benefit with pembrolizumab over chemotherapy (14.9 vs 12.5 months). The objective response rates were similar between groups, with higher response rates seen with increasing CPS in the pembrolizumab group. The median duration of response was 12.2 months with pembrolizumab and 8.3 months with chemotherapy.