PDCD1 and neoplasm: The mechanism by which tumors with high MSI and TMB respond better to PD-1 inhibitor therapy may be that more mutated genes produce more tumor antigens, making the tumor more immunogenic and thus resulting in greater lymphocyte infiltration, and that hypermutated tumors may contain more tumor-specific neoantigens and a greater number of tumor-infiltrating lymphocytes (TILs) 42, 45, 47.