Nivolumab is a human immunoglobulin G4 (IgG4) monoclonal antibody (HuMAb) that selectively blocks the interaction between programmed cell death 1 (PD-1), which is expressed on activated T cells, and PD-1 ligand 1 (PD-L1) and 2 (PD-L2), which are expressed on immune cells and tumor cells. This evidence concerns the gene PDCD1 and neoplasm.