Tumor mutation burden (TMB), neoantigen load (NAL), copy alternation number (CAN), mismatch repair deficiency (dMMR), microsatellite instability (MSI), tumor microenvironment (TME), especially the expression of PD-1/PD-L1 and mutation of some specific genes are considered to be predictive markers of immunotherapy in GC patients [16–18]. The gene discussed is PDCD1; the disease is neoplasm.