Setmelanotide

What it is

Setmelanotide is an eight-amino-acid cyclic analog of alpha-melanocyte-stimulating hormone. IMCIVREE is the defined FDA-approved product containing setmelanotide acetate; RM-493 is the development code. The active ingredient and the finished drug are related, not interchangeable concepts.

The approval and trial evidence are product-, formulation-, route-, population-, and cause-specific. The ingredient name alone does not establish the acetate salt, concentration, excipients, sterility, stability, storage history, manufacturing controls, or approval of another product.

Why people care

Setmelanotide has a real FDA approval and meaningful rare-obesity trial evidence, including a new acquired-hypothalamic-obesity indication in 2026. Reader confusion arises when that narrow product-and-cause record is shortened to a general weight-loss-peptide claim.

What humans actually show

Setmelanotide is the active peptide in the FDA-approved IMCIVREE product. The March 2026 United States label covers weight reduction in defined acquired hypothalamic obesity, Bardet-Biedl syndrome, and genetically bounded POMC, PCSK1, or LEPR deficiency populations. It is not a general-obesity approval and does not authenticate a compounded or unidentified product.

• approved label — Adults and pediatric patients aged four years and older with acquired hypothalamic obesity due to hypothalamic injury or dysfunction; Route: Subcutaneous IMCIVREE or placebo in the labeled randomized clinical program; Outcome: Percent change in body-mass index after 52 weeks: The label reports a placebo-adjusted least-squares mean BMI difference of -18.40 percentage points, with a 95% confidence interval from -21.94 to -14.85, in a modified intention-to-treat analysis of 142 randomized and treated participants: 94 assigned to IMCIVREE and 48 to placebo. The seam: The result applies to defined acquired hypothalamic obesity, not general obesity; The label reports an expanded 142-person analysis; the July 2026 paper reports the prespecified 120-person pivotal cohort; The sponsor's SEC-filed statement identifies the additional 22 participants as 12 from a Japanese cohort and 10 supplemental participants; The sponsor release reports slightly different topline estimates for the same 142-person population; the final FDA label's FDA-reviewed -18.40 percentage-point placebo-adjusted estimate, -15.84% setmelanotide estimate, and 2.55% placebo estimate govern this draft; The result belongs to the labeled product and trial conditions; A trial-average result does not predict an individual outcome.
• randomized human — The prespecified 120-participant TRANSCEND pivotal cohort—81 assigned to setmelanotide and 39 to placebo—aged four to 66 years with acquired hypothalamic obesity; Route: Subcutaneous setmelanotide or placebo after an escalation period; Outcome: Body-mass-index change and maximal daily hunger score at 52 weeks: The July 2026 paper reports a least-squares mean BMI change of -16.5% with setmelanotide and 3.3% with placebo; among participants aged 12 years and older, the reduction in maximal daily hunger was also greater with setmelanotide. The seam: The paper reports the prespecified pivotal cohort rather than the label's expanded 142-person analysis; The paper's estimates and the label's expanded-population estimates are not interchangeable; The population had defined acquired hypothalamic obesity; The paper was sponsor funded.
• randomized human — People aged six years and older with obesity and Bardet-Biedl syndrome or Alström syndrome; Route: Subcutaneous setmelanotide or placebo for 14 weeks, followed by open-label setmelanotide; Outcome: At least 10% body-weight reduction after 52 weeks of active treatment: Among participants aged 12 years and older with Bardet-Biedl syndrome, 32.3% reached at least 10% body-weight reduction after 52 weeks. The investigators described the Alström syndrome result as inconclusive. The seam: Only the first 14 weeks were placebo controlled; The 52-week responder analysis was not a 52-week parallel placebo comparison; The population had a rare syndromic condition; The current United States label includes Bardet-Biedl syndrome, not Alström syndrome.
• other human — Ten participants with POMC deficiency obesity and eleven with LEPR deficiency obesity in single-arm phase 3 cohorts; Route: Subcutaneous setmelanotide in open-label studies with a withdrawal component; Outcome: At least 10% body-weight reduction at approximately one year: Eight of ten POMC participants and five of eleven LEPR participants met the prespecified weight-loss threshold. The seam: The cohorts were very small; The pivotal treatment periods were open label; The conditions were genetically defined severe early-onset obesity; Results cannot be transferred to general obesity, a benign variant, or an unidentified product.

Mechanistic and nonhuman evidence

• mechanistic — Labeled pharmacology and nonclinical evidence; Route: MC4-receptor agonism; Outcome: Hunger, satiety, energy expenditure, food intake, and pigmentation pathways: The label states that setmelanotide may restore insufficient MC4-pathway activity in the labeled conditions and that MC1-receptor activation increases melanin and skin pigmentation. The seam: The pathway explanation is partly based on nonclinical evidence; Mechanism does not establish efficacy for an unlisted cause of obesity; MC1 activity also relates to labeled pigmentation warnings.

FDA and U.S. status

The March 2026 IMCIVREE label is FDA approved to reduce excess body weight and maintain weight reduction long term in adults and pediatric patients aged four years and older with acquired hypothalamic obesity, and in adults and pediatric patients aged two years and older with Bardet-Biedl syndrome or POMC, PCSK1, or LEPR deficiency meeting the label's genetic-testing boundary. The label expressly excludes general polygenic obesity and other obesity not related to those listed causes. The openFDA record updated July 28, 2026 lists NDA213793 IMCIVREE with Prescription marketing status.

Risks and warning limits

• approved label: The label warns about disturbance in sexual arousal, depression and suicidal ideation, serious hypersensitivity, and skin hyperpigmentation with darkening or development of melanocytic nevi.
• approved label: For acquired hypothalamic obesity, the label adds warnings for acute adrenal insufficiency in patients with secondary adrenal insufficiency and sodium imbalance in patients with central diabetes insipidus or arginine-vasopressin deficiency.
• human trial: Common reactions across labeled programs include skin hyperpigmentation, injection-site reactions, nausea, headache, diarrhea, abdominal pain, vomiting, depression, and spontaneous penile erection; exact frequencies differ by population and trial.

What remains unknown

• A separate peer-reviewed report of the expanded 142-participant analysis was not identified; the July 2026 paper reports the prespecified 120-participant pivotal cohort.
• The cited trials do not establish efficacy in general polygenic obesity or another unlisted cause; the current label expressly excludes those uses.
• The clinical drug-drug-interaction profile is not characterized because the label reports no clinical interaction studies.
• The identity, potency, sterility, stability, and excipient profile of a compounded or unidentified product cannot be inferred from the ingredient name.

Product identity and quality limits

• IMCIVREE is a defined approved setmelanotide-acetate drug product; the name setmelanotide alone does not establish the salt, formulation, excipients, or manufacturing controls.
• FDA states that compounded drugs are not FDA approved. The IMCIVREE label cannot be transferred to a compounded or unidentified material.

What has been studied together

• Setmelanotide with other medicines — no direct evidence: The label reports low in-vitro pharmacokinetic interaction potential but states that no clinical drug-drug-interaction studies have been conducted. This is not clinical compatibility clearance.
• Setmelanotide with therapies for central diabetes insipidus or arginine-vasopressin deficiency — known label boundary: The acquired-hypothalamic-obesity label warns about sodium imbalance in this subgroup and establishes a specific monitoring boundary. It does not establish general safety for a combination or an individual.

What people are hearing

These are claims this profile checks, not established conclusions.

• Claim under review: “IMCIVREE approval means setmelanotide is FDA approved for general obesity.”
• Claim under review: “An MC4-receptor mechanism establishes benefit for any cause of obesity.”
• Claim under review: “A material described as setmelanotide is equivalent to the approved IMCIVREE product.”

Questions readers raise

• No reproducible community sample was collected for this profile.

The community-signal layer is not efficacy or safety evidence. Its current limits are:

• No reproducible community sample has been collected for this profile.
• Self-reports would be subject to selection and reporting bias.
• The identity of a product described in a self-report could not be verified.
• Concurrent medicines, health conditions, diet, and behavior could confound an anecdote.
• Reported outcomes could not be independently verified.
• Anecdotes cannot establish efficacy, safety, approval, product identity, or interaction compatibility.

What would change this answer

• A revised FDA label or approval action would change the exact United States indication, population, age, or warning boundary.
• A future peer-reviewed report of the expanded analysis or additional FDA review material could further document how the 12 Japanese and 10 supplemental participants were incorporated beyond the prespecified 120-person pivotal cohort.
• Clinical interaction studies could change the present no-direct-clinical-interaction-evidence boundary.

Sources and records

• WADA — 2026 Prohibited List

• IMCIVREE (setmelanotide) prescribing information, revised March 2026 — U.S. Food and Drug Administration
• IMCIVREE supplemental approval letter for acquired hypothalamic obesity — U.S. Food and Drug Administration
• Drugs@FDA API exact active-ingredient search for setmelanotide — U.S. Food and Drug Administration
• Compounding and the FDA: Questions and Answers — U.S. Food and Drug Administration
• ClinicalTrials.gov intervention search for setmelanotide — ClinicalTrials.gov
• PubMed search for setmelanotide in human records — National Library of Medicine
• TRANSCEND acquired hypothalamic obesity phase 3 registry — ClinicalTrials.gov
• Setmelanotide for the Treatment of Acquired Hypothalamic Obesity — PubMed
• Rhythm Pharmaceuticals description of the expanded 142-participant TRANSCEND analysis — Rhythm Pharmaceuticals filing with the U.S. Securities and Exchange Commission
• Efficacy and safety of setmelanotide in Bardet-Biedl syndrome and Alström syndrome — PubMed
• Efficacy and safety of setmelanotide in severe obesity due to LEPR or POMC deficiency — PubMed
• Setmelanotide POMC deficiency obesity registry — ClinicalTrials.gov
• Setmelanotide LEPR deficiency obesity registry — ClinicalTrials.gov