CTLA4 and neoplasm: One way of triggering or enhancing an anti-tumor reaction is the targeted administration of immunomodulating drugs such as pro-inflammatory cytokines or checkpoint inhibitors such as programmed cell death protein-1 (PD-1), programmed cell death-ligand 1 (PD-L1) and cytotoxic T-lymphocyte associated protein 4 (CTLA-4).