Real-World Effects of MC4R Agonist Therapy in BBS and Severe Genetic Obesity

Real-World Effectiveness, Safety and Patient-reported Outcomes of Setmelanotide in Patients With Bardet-Biedl Syndrome: A Prospective Mono Centric Observational Interventional Study

Bardet-Biedl syndrome (BBS) and other rare disorders associated with impairment of the melanocortin-4 receptor (MC4R) pathway are characterized by severe early-onset obesity, hyperphagia, and substantial morbidity. Setmelanotide, an MC4R agonist, is approved in Europe for selected genetic obesity disorders and reimbursed in Germany for eligible patients. This study aims to evaluate the effectiveness, safety, treatment persistence, metabolic outcomes, and patient-reported outcomes of Setmelanotide under real-world conditions. The registry is designed to allow future inclusion of additional MC4R agonists as they become approved and clinically available. The study will primarily be conducted at University Hospital Essen and will collect longitudinal routine clinical data from pediatric and adult patients receiving MC4R agonist therapy according to approved indications.

The MC4R signaling pathway is a key regulator of appetite and energy balance. Genetic defects affecting this pathway lead to severe obesity syndromes including Bardet-Biedl syndrome and other rare monogenic obesity disorders. Although pivotal clinical trials demonstrated efficacy of Setmelanotide, evidence from routine clinical care remains limited. This study seeks to characterize treatment outcomes in everyday clinical practice, including changes in body weight, BMI, hyperphagia, metabolic parameters, quality of life, treatment adherence, and adverse events. Patients receiving approved MC4R agonist therapy will be followed prospectively. Data will be collected during routine outpatient visits and include anthropometric, clinical, laboratory, and patient-reported measures. The study infrastructure is intended to serve as a platform for future MC4R agonists approved for severe genetic obesity disorders.

Inclusion Criteria:

• clinical phenotype corresponding to Bardet-Biedl Syndrome
• genetic testing with notable finding

Exclusion Criteria:

• patients younger than the age approved for treatment with setmelanotide