PDCD1 and esophageal squamous cell carcinoma: The phase 3 RCT data described in this manuscript demonstrate that: 1] addition of a PD-1 inhibitor to conventional chemotherapy provides survival benefit in untreated, advanced NPC, ESCC, and NSCLC; and 2] some PD-1 inhibitors assessed provided benefit among patients with low/no PD-L1 expression in NPC and NSCLC albeit to a lesser degree than those with high/intermediate PD-L1 expression.