MELBASE will comprise a virtual Tumor bank collecting samples from the same unresectable stage III and stage IV patients enrolled in the study. These samples will be available in the Biological Resource Centers (CRB) of each participating center and will consist of the primary melanoma (mostly paraffin embedded), metastatic sample (s)(paraffin embedded and frozen) from at least 1 site at inclusion and during evolution, particularly before treatment modification if clinically required, DNA from peripheral blood mononuclear cells, plasma sampled at inclusion and every 6 months during 3 years.