Despite being standard of care, there are still many medical requirements related to immune checkpoint blocker based therapies such as identify patients susceptible to respond with the less adverse events, evaluate the clinical benefit of adjuvant treatment /risk of relapse and design new strategies for non-responder patients. Thus, this project aims at understanding the impact of anti-PD1 on the immune system through investigation of the phenotypic, functional, metabolic and transcriptomic profiles of circulating DC subsets and effectors in response to anti-PD1 therapy in melanoma patients. The primary objective of the study is to identify the biomarkers of response to anti-PD1 according to the type of patient before the start of the treatment.