More recently, KEYNOTE-966, which was a randomized, double-blind, placebo-controlled, phase 3 trial, evaluated patients with advanced, previously untreated biliary tract cancers who were randomized to receive gemcitabine plus cisplatin with pembrolizumab, an anti-programmed cell death-1 (anti-PD-1) antibody, or placebo [13]. Here, PDCD1 is linked to biliary tract neoplasm.