Inclusion Criteria:  Patients aged 18 to 80 Patients with unresectable or metastatic melanoma Patients with ECOG performance of 0-2 Patients able to provide written informed consent and understand the risks associated with MaaT013 Have measurable disease as per RECIST version 1.1, on a tumor evaluation (either CT scan, physical evaluation or ultrasonography) performed less than 2 weeks before screening visit Requiring a treatment with Ipilimumab and PD1 inhibitor (Nivolumab) and having no contraindication to these drugs nor to their excipients Patients unexposed to ipilimumab and anti PD1 or anti PDL1 except if they have received it in the adjuvant setting (if the last dose of Ipilimumab® or anti PD1 or anti PDL1 was received at least 6 months before randomization). Negative pregnancy test (serum) Women of childbearing potential (WOCBP) must agree to follow instructions for method(s) of contraception for the duration of study treatment with nivolumab, ipilimumab and 6 months after the last dose of study treatment (ie, 30 days (duration of ovulatory cycle) plus the time required for the investigational drug to undergo approximately five half-lives) Males who are sexually active with WOCBP must agree to follow instructions for method(s) of contraception for the duration of study treatment with nivolumab, ipilimumab and 7 months after the last dose of study treatment {i.e., 90 days (duration of sperm turnover) plus the time required for the investigational drug to undergo approximately five half-lives.} Hemoglobin ≥9 g/dL Platelets ≥ 100000mm3 Neutrophils ≥ 1500/mm3 Creatinine Clearance ≥ 50mL/mn AST ≤ 3N ALT ≤ 3N Total bilirubin ≤ 1.5N (except subjects with Gilbert Syndrome, who can have total bilirubin < 3.0 mg/dL) Alkaline phosphatase ≤ 3N INR < 1.5 Prothrombin ≥ 70% TCA < 1.2 No Hepatocellular insufficiency  Exclusion Criteria:  Pregnant or breastfeeding women Antibiotics in the last two weeks prior to the FMT Inability to retain enemas Expected to require any other form of systemic or localized anti-neoplastic therapy while on study Active infection requiring systemic therapy. Active, known or suspected autoimmune disease. No health insurance, Patients already included in a clinical research other than an observational study (e.g: registry, cohort). Patient on AME (state medical aid) (unless exemption from affiliation) Patients guardianship/legal protection/curatorship Contraindication to fecal transplantation Known hypersensitivity to Normacol or Moviprep® or equivalent patent medicines enema or one of their components. Fluid-electrolyte disorders with sodium retention (heart failure, hyperaldosteronism, drug-induced edema) Recent acute coronary syndrome or unstable ischemic heart disease Congestive heart failure ≥ Class III or IV as defined by New York Heart Association Hypersensitivity to the active substances or to any of the excipients: Aspartame (E951), Acesulfame, potassium (E950), lemon flavor (maltodextrin, citral, lemon essential oil, lime essential oil, xanthan gum, vitamin E) Gastrointestinal obstruction or perforation Gastric emptying disorders (gastroparesis), Ileus, Phenylketonuria (due to the presence of aspartame), Deficiency in glucose-6-phosphate dehydrogenase (due to the presence of ascorbate), Toxic megacolon, in severe forms of inflammation of the intestinal tract, including Crohn's disease and ulcerative colitis.