CTLA4 and neoplasm: It has been reported in literature that some Immune Checkpoints, such as PD-1, PD-L1 and CTLA-4, are expressed not only on immune cells but also on many different types of tumors, and that immunomodulatory mAbs specific for these targets can affect tumor cell viability even in the absence of immune cells [6,28,29,30,31].