CTLA4 and cancer: Current cancer immunotherapy by immune checkpoint blockade therapy (ICT) has been harnessing this fact to unleash the power of T cells by eradicating negative signals such as cytotoxic T lymphocyte associated antigen-4 (CTLA-4), and programmed death-1 (PD-1)/programmed death ligand-1 (PD-L1) that hinder T cell function 1, 3.