In this context, the aim of our program is to identify and validate an immune signature predictive of anti-PD-1 benefit in the treatment of advanced melanoma patients. To this aim, tumor samples from 120 melanoma patients enrolled prospectively, treated with anti-PD1 mAb alone or combined with anti CTLA4, will be collected as well as the corresponding peripheral blood mononuclear cells (PBMC). Tumor infiltration with immune cells will be characterized on paraffin embedded melanoma samples. The investigators will also perform whole-exome sequencing on tumors and matched PBMC samples. Our primary objective is to develop a combined immuno-signature based on an immuno-score (CD3, CD8, CD45RO…) to quantify the in situ immune populations with a dedicated image analysis system combined with the simultaneous detection of CD8-PD-1 and PD-L1 by immunofluorescence in baseline tumor samples. This will permit to predict 1-year survival of patients with advanced melanoma treated with anti-PD1 and transfer in patient's care.