ICIs increase anti-tumor immunity by blocking intrinsic downregulators of immunity, such as cytotoxic T lymphocyte antigen 4 (CTLA-4), programmed cell death protein-1 (PD-1), and its ligand programmed cell death-ligand 1 (PD-L1) (Postow et al., 2018). This evidence concerns the gene PDCD1 and neoplasm.