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Weight loss

Setmelanotide

A daily MC4-receptor agonist for specific rare genetic and acquired hypothalamic obesity—not a general obesity drug.

Moderate
Evidence rating
Evidence review

What the evidence says

Setmelanotide activates the melanocortin-4 receptor downstream of specific disrupted hunger pathways. Current FDA approval is limited to acquired hypothalamic obesity and obesity from Bardet-Biedl syndrome or confirmed POMC, PCSK1, or LEPR deficiency at defined pediatric and adult ages; it is not indicated for ordinary polygenic obesity.[1]

In small phase 3 studies of POMC or LEPR deficiency, 80% and 45% of participants respectively achieved at least 10% weight loss at about one year, alongside reduced hunger. These were open-label rare-disease trials with withdrawal periods, and the denominators were only 10 and 11 participants.[2]

A randomized Bardet-Biedl trial found 32.3% of participants aged 12 or older achieved at least 10% loss after 52 weeks. In a 2026 randomized trial of 142 people with acquired hypothalamic obesity, the placebo-adjusted BMI difference after 52 weeks was about 18.4 percentage points, leading to the expanded indication.[3][4][1]

Daily injection-site reactions and marked skin darkening are common. The label also warns about sexual adverse reactions, depression or suicidal ideation, and benzyl-alcohol toxicity in neonates and low-birth-weight infants. Diagnosis and treatment require specialist supervision, genetic or clinical confirmation, and ongoing response and mental-health monitoring.[1][5]

Potential benefits

  • Can produce substantial weight and hunger reductions in responsive POMC, PCSK1, or LEPR deficiency and Bardet-Biedl syndrome.[2][3]
  • Produces large average BMI reductions in acquired hypothalamic obesity compared with placebo.[4][1]

Side effects and cautions

  • Commonly causes skin hyperpigmentation, injection-site reactions, nausea, headache, vomiting, or spontaneous erections.[1][3]
  • Depression, suicidal ideation, and other sexual adverse reactions require active monitoring.[1]
How we scored it

Evidence breakdown

Large effects occur in genetically or clinically defined target populations, but trials are small for rare disorders, industry-sponsored, and do not support use for ordinary polygenic obesity.

Clinical relevanceHigh

Trials measure body weight, BMI, hunger, hyperphagia, and quality of life.

Study qualityModerate

Randomized evidence exists for Bardet-Biedl and hypothalamic obesity, while monogenic trials are necessarily tiny and partly open-label.

Safety dataModerate

Labeling defines common effects and serious warnings, but exposed populations remain small.

References

Full source list

  1. IMCIVREE prescribing information

    U.S. Food and Drug Administration · 2026

  2. Efficacy and safety of setmelanotide in individuals with severe obesity due to LEPR or POMC deficiency

    Lancet Diabetes & Endocrinology · 2020

  3. Efficacy and safety of setmelanotide in patients with Bardet-Biedl syndrome and Alström syndrome

    Lancet Diabetes & Endocrinology · 2022

  4. Setmelanotide for the Treatment of Acquired Hypothalamic Obesity

    New England Journal of Medicine · 2026

  5. Real-World Efficacy and Safety of Setmelanotide in Adults With Monogenic or Syndromic Obesity

    Obesity · 2025