CTLA4 and neoplasm: Single-agent checkpoint inhibitors can reverse tumor-induced downregulation of T-cell function by blocking the engagement of checkpoint receptors like cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and programmed-death-1(PD-1) on the surface of T-cells with their cognate ligands expressed on tumor cells.4, 5, 6 This allows activation of the cytotoxic T-cell via engagement of the T-cell receptor (TCR) with antigenic peptides presented in the class I major histocompatibility complex (MHC) on tumor cells.