FDA approves setmelanotide for acquired hypothalmic obesity in patients 4 years and older

The FDA has approved an expanded indication for setmelanotide (Imcivree) to treat acquired hypothalamic obesity (HO) in adults and pediatric patients 4 years and older.

The approval, announced March 19, 2026, by Rhythm Pharmaceuticals, makes setmelanotide the first FDA-approved therapy for this rare condition, which is characterized by accelerated and sustained weight gain following injury to or dysfunction of the hypothalamus.¹

“Setmelanotide has shown effectiveness in targeting the underlying biology of acquired HO,” said Ashley Shoemaker, MD, MSCI, associate professor of pediatrics and pediatric endocrinology at Vanderbilt Health. “Patients treated with setmelanotide experienced meaningful reductions in BMI and hunger, demonstrating the therapy’s ability to deliver clinically significant outcomes in both children and adult patients. Acquired HO is a severe disease that requires early and proactive management. With the availability of Imcivree, physicians can offer a targeted therapy.”¹

Acquired HO most commonly follows the growth or treatment of craniopharyngioma, astrocytoma, or other hypothalamic-pituitary tumors, though traumatic brain injury, stroke, and inflammatory causes are also recognized. Hypothalamic injury disrupts MC4R pathway signaling, impairing the regulation of hunger and energy expenditure and driving rapid weight gain that is resistant to conventional dietary and lifestyle interventions. Rhythm Pharmaceuticals estimates that approximately 10,000 people in the US are living with the condition.¹

Mechanism and prior approvals

Setmelanotide is an MC4R agonist designed to restore impaired signaling along the MC4R pathway. The FDA first approved setmelanotide in 2020 for adults and pediatric patients 6 years and older with obesity due to POMC, PCSK1, or LEPR deficiency, and subsequently for Bardet-Biedl syndrome.³ The acquired HO approval is the first indication extending setmelanotide to an obesity phenotype driven by structural rather than genetic disruption of the MC4R pathway. The current approval also extends eligibility to patients as young as 4 years; previously, the minimum age was 6 years.

Phase 3 TRANSCEND trial

The approval was supported by data from the global, randomized, double-blind, placebo-controlled phase 3 TRANSCEND trial, which enrolled 142 patients with acquired HO 4 years and older. Participants were randomly assigned 2:1 to receive once-daily subcutaneous setmelanotide, titrated to 1.5 to 3.0 mg based on age, weight, and tolerability, or placebo for 52 weeks.¹

The trial met its primary end point. Patients treated with setmelanotide (n = 94) achieved a mean body mass index (BMI) reduction of 15.8% from baseline at 52 weeks compared with a mean increase of 2.6% in the placebo arm (n = 48), for a placebo-adjusted BMI reduction of 18.4% (P < .0001).¹ These results built on earlier phase 2 findings published in Lancet Diabetes and Endocrinology, in which 89% of 18 patients met the primary end point of at least a 5% BMI reduction after 16 weeks of treatment, with a mean BMI reduction of 15% across the study population.²

Safety

Setmelanotide was generally well tolerated in the TRANSCEND study. Adverse events occurring in more than 20% of participants included skin hyperpigmentation, nausea, vomiting, and headache.¹

Several safety considerations are relevant to the pediatric population. Patients with acquired HO and secondary adrenal insufficiency experienced serious adverse reactions related to acute adrenal insufficiency in 5% of setmelanotide-treated patients. Sodium imbalances, including both hyponatremia and hypernatremia, were observed in patients with concomitant central diabetes insipidus. Depression and suicidal ideation have been reported with setmelanotide across indications and warrant monitoring in all patients.¹

References

1. Rhythm Pharmaceuticals announces FDA approval of Imcivree (setmelanotide) for patients with acquired hypothalamic obesity. News release. Rhythm Pharmaceuticals. March 19, 2026. Accessed March 19, 2026. https://ir.rhythmtx.com/news-releases/news-release-details/rhythm-pharmaceuticals-announces-fda-approval-imcivreer-1
2. Roth CL, Schulten S, Meeker D, et al. Setmelanotide for the treatment of acquired hypothalamic obesity: a phase 2, open-label, multicentre trial. Lancet Diabetes Endocrinol. 2024;12(6):385-393. doi:10.1016/S2213-8587(24)00085-8
3. Walter K. FDA approves setmelanotide for obesity caused by genetic deficiencies. HCPLive. November 27, 2020. Accessed March 19, 2026. https://www.hcplive.com/view/fda-setmelanotide-obesity-genetic-deficiencies