PDCD1 and gastric cancer: It is easy to conceive that patients with an immunity_H subtype of stage IV GC will have a greater likelihood of response to anti-PD-1/PD-L1 therapy when compared with patients in other stage IV GC subtypes, because PD-L1 is more noticeably demonstrated in immunity_H, and PD-L1 expression is a predictive biomarker for response to immunotherapy directed to PD-1/PD-L1 [59].