CTLA4 and cancer: Tremendous advances have been made in the treatment of cancer patients using ICIs targeting programmed cell death protein 1 (PD-1), programmed death ligand 1 (PD-L1), and cytotoxic T lymphocyte-associated antigen 4 (CTLA-4).3,4,8,38 However, the response rate to ICIs for solid tumors is relatively low.