CTLA4 and neoplasm: This allows the tumor-reactive T-cells to mount an effective anticancer response (Figure 1).10,11 There are currently three well-studied immune targets with good clinical data and approved therapeutic agents that are widely used: cytotoxic T-lymphocyte–associated protein 4 (CTLA-4), programmed death-1 protein (PD-1), and programmed death-1 ligand.10,11 CTLA-4 is an inhibitory receptor belonging to the CD28 Ig subfamily, which is constitutively expressed on the surface of immunosuppressive T-regulatory cells.