PDCD1 and gastric cancer: For instance, pembrolizumab (anti-PD-1 antibody) has been shown a significant survival benefit in the treatment of GC in many studies and has been approved by the Food and Drug Administration (FDA) as a third-line treatment for PD-L1-positive GC patients as well as patients with unresectable or metastatic, highly microsatellite instability or mismatch repair-deficient (118).