PDCD1 and neoplasm: However, at present, ICIs are not suitable for everyone, and patient selection for ICIs depends mainly on some molecular biomarkers currently, such as programmed cell death protein 1 (PD-1), programmed death-ligand 1 (PD-L1), tumor mutational burden (TMB), CD8+ T cell infiltration, Tim-3, and so on (76–78).