Efforts have been made to enhance the action of T and B cells targeting tumor cells, and immune checkpoint inhibitors targeting programmed cell-death protein 1 (PD1), programmed death ligand 1 (PD-L1), or cytotoxic T-lymphocyte-associated protein 4 may be effective in patients with GC for palliative purposes [18]. Here, PDCD1 is linked to gastric cancer.