Notably, the blockade of immunosuppressive checkpoints, such as T-lymphocyte-associated antigen 4 (CTLA4), programmed cell death 1 (PD1) protein, and programmed cell death-ligand 1 (PD-L1), has demonstrated objective clinical responses in various cancers and other malignant neoplasms [17, 18]. The gene discussed is PDCD1; the disease is cancer.