CD274 and gastric cancer: The KEYNOTE-59, open-label, phase II trial, evaluated the safety and efficacy of monotherapy with pembrolizumab, a humanized monoclonal IgG4 kappa antibody that binds to the PD-1 receptor, blocking its interaction with PD-L1 and PD-L2.26 The trial involved a cohort of 259 patients from 16 international locations with previously treated advanced GC or GEJ cancer.26 The objective response rate (ORR) associated with pembrolizumab treatment was 11.6%, 2.3% of the patients had complete response, and the median OS was 5.6 months.