ICI targeting the programmed death receptor (ligand) 1 (PD-1/PD-L1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) axis are widely applied in solid malignancies such as melanoma, lung cancer, renal cell carcinoma, head and neck squamous cell carcinoma, among others. This evidence concerns the gene CTLA4 and melanoma.