Tumor cells can achieve immune escape by hijacking inhibitory immune checkpoints, such as programmed cell death-1 protein/ligand (PD-1/PD-L1), cytotoxic T lymphocyte antigen 4 (CTLA4), T cell immunoglobulin and mucin domain-containing protein 3 (TIM-3), which regulates the function and survival of immune cells and facilitates immune suppressive microenvironment (1, 2). The gene discussed is PDCD1; the disease is neoplasm.