A Study of Setmelanotide in Patients With Prader-Willi Syndrome

Key Inclusion Criteria: * Confirmed diagnosis of Prader-Willi Syndrome (PWS) * Age 6 to 65 * BMI ≥30 kg/m2 for patients ≥18 years of age or BMI ≥95th Percentile for age and sex * Agree to use a highly effective form of contraception and follow the study contraception requirements throughout study duration and for 90 days after. * Patient and/or guardian is able to communicate well with the Investigator, understand and comply with the requirements of the study, and understand English and sign the written informed consent. Exclusion Criteria: * Use of weight modulating medications * Abnormal eGFR, ALT, AST, and bilirubin values * Current, clinically significant pulmonary, cardiac, metabolic, or oncologic disease considered severe enough to interfere with the trial and/or confound the results. * Participation in any clinical trial with an investigational drug/device within 3 months or 5 half-lives, whichever is longer, prior to the first trial dose * Hypersensitivity to setmelanotide * Diagnosis of severe psychiatric disorders * Pregnant and/or breastfeeding Other protocol defined Inclusion/Exclusion criteria may apply.