Pembrolizumab in Triple-Negative Breast Cancer

To the Editor: In the KEYNOTE-355 trial reported by Cortes et al. (July 21 issue),(1) the overall survival benefit of pembrolizumab plus chemotherapy among patients with advanced triple-negative breast cancer whose tumors expressed programmed death ligand 1 (PD-L1) with a combined positive score of 10 or more was quantified mainly on the basis of a hazard ratio of 0.73 and a P value of 0.0185, which barely surpassed the prespecified alpha level of 0.0227. However, it is unclear how the clinical benefit of pembrolizumab plus chemotherapy could be determined on the basis of a ratio alone without the hazard value . . .