PDCD1 and gastric cancer: Furthermore, the availability of potentially relevant predictive biomarkers (HER2, VEGF, FGFR2) and immune checkpoints (T cell immunoreceptor with Ig and ITIM domains [TIGIT], programmed cell death 1 [PD1], cytotoxic T-lymphocyte-associated protein 4 [CTLA4]) (6) in GC provides limited assistance in its diagnosis and treatment.