Abstract: The present invention relates to autoantibody biomarkers associated with melanoma. The autoantibody biomarkers can be used to detect or diagnose melanoma and can also be used to inform treatment of melanoma patients, particularly treatment with checkpoint inhibitors. The autoantibody biomarkers can be used in a variety of methods including: methods of selecting melanoma patients for treatment; methods of predicting responsiveness to treatment; methods of predicting survival responsive to treatment; and methods of predicting the risk of immune-related adverse events (irAEs) in patients treated with checkpoint inhibitors.