Observational Study of Patients With Advanced Melanoma (Skin Cancer) to Assess if IOpener®-Melanoma Test Can Predict Response to Immunotherapy.

Inclusion Criteria: * First line treatment for unresectable stage III or IV cutaneous melanoma (according to AJCC version 8) with anti-PD1 monotherapy (nivolumab or pembrolizumab) or anti-PD1 + anti-CTL4A combination therapy (nivolumab and ipilimumab). * Anticipated life expectancy exceeding 3 months. * Aged 18 years or older and able to provide written informed consent. Patients who have completed adjuvant treatment with anti-PD1 immunotherapy at least 6 months ago can be included. Exclusion Criteria: * Prior treatment for irresectable stage III or stage IV melanoma with BRAF/MEK inhibitors. * Presence of progressive/symptomatic brain metastases at baseline. * WHO performance score ≥ 2. * Adjuvant treatment with anti-PD1 immunotherapy received within the last 6 months. * Patients undergoing experimental treatments or therapies. * Presence of any medical or other condition that in the opinion of the investigator(s) would preclude the participation in a clinical study. * Unwillingness or inability to comply with study and follow-up procedures.