CTLA4 and neoplasm: Combinatorial administration of anti-CTLA-4 with IL-2Cx, a complex of IL-2/anti-IL-2 which directs IL-2 to NK and CD8+ T cells but not Tregs, or IL-15/IL-15Ralpha complexes further tips the tumoral effector/regulatory cell ratio in favor of activated NK cells and enhances tumor control (82, 101).