Breast Cancer Coverage from Every Angle

KEYNOTE-119 Trial of Pembrolizumab Versus Chemotherapy for Triple-Negative Breast Cancer

By: Cordi Craig
Posted: Thursday, November 7, 2019

Although pembrolizumab monotherapy was associated with lower rates of high-grade toxicities among patients with metastatic triple-negative breast cancer than chemotherapy, it did not significantly improve overall survival, according to the phase III KEYNOTE-119 trial. However, Javier Cortés, MD, PhD, of the Vall d’Hebron Institute of Oncology, Barcelona, and colleagues noted that the treatment effect of pembrolizumab appeared to increase as PD-L1 enrichment increased. The study was presented at the European Society for Medical Oncology (ESMO) Congress 2019 in Barcelona (Abstract LBA21) and published in the Annals of Oncology.

The investigators randomly assigned patients with metastatic triple-negative breast cancer to receive pembrolizumab (n = 312) or physician’s choice of capecitabine, eribulin, gemcitabine, or vinorelbine (n = 310). The investigators stratified patients by PD-L1 status (positive or negative) and explored treatment effects on overall survival among patient groups based on PD-L1 Combined Positive Score (CPS; ≥ 10, ≥ 1, and in all patients).

Pembrolizumab did not significantly improve overall survival, regardless of the PD-L1 CPS (P > .0574). However, the treatment effect appeared to improve with increasing PD-L1 CPS. The hazard ratios of patient groups with a CPS of at least 10, at least 1, and in all patients were 0.78, 0.86, and 0.97, respectively. Pembrolizumab did not improve progression-free survival, safety, or overall response rate.

High-grade adverse events were less common in patients treated with pembrolizumab (14%) than chemotherapy (36%). There was one treatment-related death in the pembrolizumab group and two deaths in the chemotherapy group. 

Disclosure: For full disclosures of the study authors, visit

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