It is also expressed on other immunecells such as B lymphocytes, natural killer (NK) cells, and myeloid derivedsuppressor cells (MDSCs).27,28 Interaction betweenPD-1 and its ligands, PD-L1 and PD-L2, on tumor cells leads todownregulation of T-cell response in the tumor microenvironment29,30 (Figure 1). This evidence concerns the gene CD274 and neoplasm.