Setmelanotide (Imcivree)

Written by The Peptide Record editorialClinical review not yet completedLast reviewed 12 September 2026

Setmelanotide is the one member of this site's melanocortin family — alongside PT-141, Melanotan I and Melanotan II — with a real, current, and actively expanding FDA approval for obesity itself. It's a genuinely narrow drug: approved only for patients whose obesity is confirmed by genetic testing to come from POMC, PCSK1 or LEPR pathway deficiency, or from acquired hypothalamic damage. Real trial evidence backs both approvals, and the label reads nothing like a tanning or libido drug despite sharing a receptor family with those.

In brief

Should you care? Yes if you've seen PT-141, Melanotan I or Melanotan II on this site — setmelanotide is the melanocortin-family drug with a real, current, obesity-specific approval, not a tanning or libido one.

The short version

FDA-approved (Imcivree, 27 November 2020) for chronic weight management in patients with obesity from confirmed POMC, PCSK1 or LEPR deficiency — genetic testing required.
Expanded 19 March 2026 to acquired hypothalamic obesity, based on a positive placebo-controlled Phase 3 trial.
MC4R-selective — a narrower mechanism than Melanotan II's non-selective MC1/MC3/MC4 activity.

What it is, and its real approval

Setmelanotide is a melanocortin-4 receptor (MC4R) agonist developed by Rhythm Pharmaceuticals. FDA approved it as Imcivree on 27 November 2020 — the first approved therapy for obesity caused by proopiomelanocortin (POMC), proprotein convertase subtilisin/kexin type 1 (PCSK1), or leptin receptor (LEPR) deficiency, three rare genetic disorders that knock out a person's ability to signal fullness through the MC4R pathway. The approval requires genetic testing to confirm one of these deficiencies before prescribing — a real biomarker gate, not a marketing label.

The trial evidence

The pivotal data (Clément et al., Lancet Diabetes Endocrinol 2020;8(12):960-970, PMID 33137293) came from single-arm, open-label Phase 3 trials in patients with confirmed POMC or LEPR deficiency. By week 52 (year 1), 80% of patients with POMC deficiency and 45% of patients with LEPR deficiency had lost at least 10% of body weight, alongside clinically meaningful drops in hunger scores. These are real, if small (fewer than 20 patients total across both deficiency cohorts), single-arm trials in an ultra-rare population.

The 2026 expansion to acquired hypothalamic obesity

On 19 March 2026, FDA approved an expanded Imcivree indication for acquired hypothalamic obesity — weight gain caused by damage to the hypothalamus itself (from a tumor, surgery, or radiation) — in patients 4 years and older, the first approved therapy for this condition. It's backed by the Phase 3 TRANSCEND trial (142 patients: 94 on drug, 48 on placebo), which met its primary endpoint: a placebo-adjusted BMI reduction of 18.4% at 52 weeks (-15.8% on drug vs. +2.6% on placebo, p<0.0001) — a real, controlled, positive randomized result.

Still a genetically or clinically gated drug

Every approved use of setmelanotide requires a specific, confirmed cause of obesity — a genetic mutation or documented hypothalamic injury. It has no approval, and no trial evidence, for general obesity or off-label weight loss outside these populations.

Where it sits in the melanocortin family

Setmelanotide, PT-141 (bremelanotide), Melanotan I (afamelanotide) and Melanotan II all act on melanocortin receptors, but with real pharmacological differences: Melanotan I is MC1-selective (pigmentation), PT-141 and Melanotan II are non-selective across MC1/MC3/MC4 (which is why they carry libido and pigmentation effects together), and setmelanotide is comparatively MC4R-selective. Its label lists skin hyperpigmentation, nausea, vomiting and headache among common adverse reactions — a different profile from PT-141's, despite the shared receptor family.

References

FDA approval of Imcivree (setmelanotide), 27 November 2020.
Clément K et al., "Efficacy and safety of setmelanotide, an MC4R agonist, in individuals with severe obesity due to LEPR or POMC deficiency: single-arm, open-label, multicentre, phase 3 trials," Lancet Diabetes Endocrinol 2020;8(12):960-970, PMID 33137293.
FDA approval of expanded Imcivree indication for acquired hypothalamic obesity, 19 March 2026, based on the Phase 3 TRANSCEND trial (142 patients: 94 setmelanotide, 48 placebo; -18.4% placebo-adjusted BMI reduction at 52 weeks, p<0.0001).