Interim FDG PET-CT in Melanoma Metastatic Patient's Treated by Anti-PD1 Therapy

Inclusion Criteria: * Age greater than or equal to 18 years, * Patient with advanced melanoma proved histologically, not BRAF mutated, BRAFV600 mutated and wild mutated, cutaneous or unknown primary melanoma having an indication of treatment with anti-PD-1 immunotherapy by nivolumab or Pembrolizumab, * Patient having social insurance, * Patient who has signed informed consent. Exclusion Criteria: * Age less than 18 years, * Patient with ocular or mucosal melanoma, * Contraindication to PET CT examination: Severe claustrophobia, unbalanced diabetes (fasting hairy blood glucose ≥ 11 mmol), * Patient with only metastatic lesions less than 8 mm in size, with the exception of pulmonary nodules, * HIV and/or HCV (hepatitis C virus) and/or HBV (hepatitis B virus) positive serology, active autoimmune disease, * Withdrawal of informed consent, * Metastatic disease not confirmed histologically.