CTLA4 and cancer: Cytotoxic T-lymphocyte-associated antigen 4, programmed death 1 (PD-1), and programmed death-ligand 1 are most extensively studied among all inhibitory receptors.[16,17] Anti-cytotoxic T-lymphocyte-associated antigen 4 and PD-1/programmed death-ligand 1 antibodies like ipilimumab,[18] pembrolizumab, and nivolumab[19,20] have been approved by the US Food and Drug Administration for clinical application as immunotherapies.[21] Despite the pronounced efficacy of such medications, there is still a large number of cancer patients who cannot benefit from immunotherapy.