Although impressive progress has been made with this new therapeutic strategy, only a proportion of patients achieve a complete and sustained response. Studies have already identified predictive factors of treatment response that are now widely recognized. In this study, the investigators aim to identify other response factors not yet evaluated in the literature.

Inclusion Criteria:

• Age ≥ 18 years;
• Unresectable stage III or stage IV melanoma according to the AJCC classification - 8th edition;
• Curative immunotherapy treatment (anti-PD-1 and/or anti-CTLA-4);
• Treatment and follow-up at the Dermatology Department of the Strasbourg University Hospitals;
• Immunotherapy initiated between January 1, 2013, and December 31, 2021.

Exclusion Criteria:

• Primary choroidal melanoma;
• Adjuvant-intent immunotherapy;
• Less than 3 months of follow-up after the start of immunotherapy;
• Change of treatment before the first reassessment;
• Treatment and follow-up at a department other than the Dermatology Department of the Strasbourg University Hospitals.

Adult subject with unresectable stage III or stage IV melanoma according to the AJCC classification - 8th edition;