CTLA4 and melanoma: Ipilimumab, a medication that targets the CTLA-4 protein, was ineffective against melanomas that had deletions (copy number loss) of crucial IFNγ pathway genes including IRF1, IFT1/2, and amplifications (copy number increase) of IFNγ-related pathway inhibitors like SOCS1 and PIAS4 [125].