Open-Label Extension Study of Setmelanotide

Key Inclusion Criteria: * Males and females ≥2 years of age who have completed a previous setmelanotide clinical study and who have a condition or indication for which Rhythm plans further clinical development. * Agree to use a highly effective form of contraception and follow the study contraception requirements throughout study duration and for 90 days after. * Demonstrated clinical benefit in the previous setmelanotide study, as determined by the Investigator. Key Exclusion Criteria: * Any gene variant, syndromic, or acquired disease for which setmelanotide is currently approved in the United States (i.e., patients eligible for commercial setmelanotide (IMCIVREE®). * Any new or worsening depression resulting in suicidal thoughts and/or behaviors. * Discontinuation from a previous setmelanotide study. * History or close family history (parents or siblings) of melanoma. * Pregnant and/or breastfeeding women Other protocol defined Inclusion/Exclusion criteria may apply.