Ipilimumab, a cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) inhibitor, is approved for advanced melanoma and is increasingly used in combination with PD-1 inhibitors such as nivolumab and pembrolizumab across various malignancies, including metastatic renal cell carcinoma (mRCC) and non-small cell lung cancer (NSCLC) (1). This evidence concerns the gene CTLA4 and melanoma.