CTLA4 and melanoma: In particular, the inhibition of PD-1 and cytotoxic T lymphocyte antigen-4 (CTLA-4), has demonstrated clinical benefit in a number of malignancies [9] such as melanoma [10, 11], lung cancer [12], bladder cancer [13], kidney cancer [14], head and neck cancer [15], hepatocellular carcinoma [16], merkel cell carcinoma [17], Hodgkin lymphoma [18], gastric cancer [19], and microsatellite instability – high (MSI-high) tumors [20].