CTLA4 and neoplasm: The presence of neo-antigens would favor the efficacy of therapies aiming at restoring a functional immune anti-tumor activity [56] and this is true when considering both anti-PD-1 and anti-CTLA-4 antibodies, though with different mechanisms of action—i.e., anti-PD-1 being active at the tumor site, and anti-CTLA-4 at the periphery in the lymphoid organs where T cell priming takes place.