CTLA4 and neoplasm: Immune checkpoint inhibitors include anti-CTLA4, anti PD-1 and anti-programmed death ligand 1 (PD-L1) antibodies, which target CTLA4 and PD-1 receptors on the surface of T cells, and PD-L1 expressed on the surface of tumor cells, blocking the subsequent inhibitory signal, and resulting in increased T cell activation and anti-tumor immune response (Figure 2).