Over the past decade, anti-cancer immunotherapy with inhibitors of the programmed cell-death 1 receptor or ligand 1 (PD-1/PD-L1) and Cytotoxic T-cell antigen 4 (CTLA-4) has swiftly become standard of care across a wide range of previously untreatable malignancies including non-small cell lung cancer (NSCLC), melanoma and many others. Here, CTLA4 is linked to cancer.