CTLA4 and melanoma: So far, only limited IO-IO combinations have been approved for the treatment of solid tumors including ipilimumab (anti-CTLA4) with nivolumab for patients with melanoma, mesothelioma, hepatocellular carcinoma, renal cell carcinoma, non-small cell lung cancer and colorectal cancer, and relatlimab (anti-LAG3) combined with nivolumab (anti-PD1) for untreated unresectable or metastatic melanoma [42, 43].