Supplementary Material for: Clinical Improvements With Setmelanotide in a 2-Year-Old Patient With Hyperphagia and Obesity due to Leptin Receptor Deficiency: A Case Report

Introduction: Dysregulation of the melanocortin-4 receptor (MC4R) pathway can lead to severe hyperphagia and early-onset obesity. Symptoms may present before age 6 years, but there is limited clinical data on treatment outcomes in very young children. Setmelanotide, an MC4R agonist, is approved for patients age ≥2 years with rare MC4R pathway disease due to Bardet-Biedl syndrome, pro-opiomelanocortin or proprotein convertase subtilisin/kexin type 1 deficiency or leptin receptor (LEPR) deficiency. This case report describes the use of setmelanotide in a 2-year-old child with hyperphagia and obesity due to LEPR deficiency.
Case Description: The patient presented with early-onset hyperphagia, rapid weight gain, and obesity-associated delays in motor development. Following a medical assessment in May 2021 he was diagnosed with LEPR deficiency. Setmelanotide treatment via subcutaneous injection was initiated in March 2023 (patient age 2 years 4 months) at a dose of 0.5 mg/day, increased to 2.5 mg/day in 0.5 mg increments, and the patient was followed for 23 months. Following treatment initiation, significant clinical improvements were observed, including reductions in hyperphagia, food intake and cravings, and body mass index (BMI). Motor skill function also improved, with the child achieving milestones such as crawling and kneeling. Reported adverse events included skin rash and skin hyperpigmentation.
Conclusion: Setmelanotide treatment started in a 2-year-old patient and continued for 23 months led to reductions in hyperphagia and food-seeking behavior, as well as improved motor skill function, BMI, and blood lipids. These findings support the use of setmelanotide in young children with hyperphagia and obesity due to LEPR deficiency.