Notably, retrospective cohorts analysis of melanoma patients treated with cytotoxic T-lymphocyte associated protein 4 (CTLA-4) inhibitors revealed a unique signature of cancer-germline antigens that could predict resistance uniquely to blockade of CTLA-4 (not programmed cell death protein 1 or PD-1), and that was associated with autophagy suppression in tumors [52]. This evidence concerns the gene PDCD1 and melanoma.