CD274 and cancer: Nivolumab, which is a fully human immunoglobulin (Ig) G4 programmed death 1 (PD-1) antibody, selectively inhibits the interaction between PD-1 (which is expressed on activated T cells) and PD-1 ligand 1 (PD-L1) and 2 (PD-L2) (which are expressed on antigen-presenting cells [APCs] and cancer cells) [9].