ICIs, which target programmed cell death-1 (PD-1), programmed cell death ligand-1 (PD-L1), and cytotoxic T-lymphocyte-associated protein-4 (CTLA-4), have extended survival in many tumor types, including metastatic melanoma that has historically had poor survival due to low response to traditional cytotoxic regimens. This evidence concerns the gene CTLA4 and neoplasm.