The pronounced clinical activity of checkpoint inhibitors including antibodies directed against CTLA-4 [2], PD-1 [4, 78] and PD-L1 [5, 79] has transformed the care of several cancers including melanoma, renal cell carcinoma, NSCLC, bladder cancer, head and neck cancer, Hodgkin lymphoma, and others. Here, CTLA4 is linked to melanoma.