FDA approves Imcivree for acquired hypothalamic obesity in adults and children

The FDA has approved an expanded indication for Imcivree (setmelanotide) to treat acquired hypothalamic obesity in adults and children aged 4 and older, Rhythm Pharmaceuticals said on March 19, 2026. The company said it is the first and only FDA-approved therapy for the condition ^[1].

Acquired hypothalamic obesity is a rare disease marked by accelerated and sustained weight gain caused by injury to the hypothalamus or hypothalamic dysfunction ^[1]. It most often follows the growth or treatment of craniopharyngioma, astrocytoma or other hypothalamic-pituitary tumors, and can also follow traumatic brain injury, stroke or inflammation, according to the company. It can appear as early as six months after hypothalamic injury. Rhythm estimates about 10,000 people in the United States live with the condition ^[1].

Setmelanotide is an MC4R agonist, a different drug class from GLP-1 medicines such as semaglutide and tirzepatide. The MC4R pathway regulates energy expenditure, hunger and body weight, and the company says acquired hypothalamic obesity involves impaired signaling along that pathway ^[1].

What the trial found

The approval rests on the global Phase 3 TRANSCEND trial, which enrolled 142 patients with acquired hypothalamic obesity ^[1]. The study met its primary endpoint with a placebo-adjusted BMI reduction of 18.4%. Patients taking setmelanotide (n=94) had a 15.8% mean reduction in BMI from baseline, while patients on placebo (n=48) had a 2.6% increase at 52 weeks (p<0.0001) ^[1].

The company said setmelanotide was generally well tolerated in the trial. The most common adverse events, affecting more than 20% of participants, were skin hyperpigmentation, nausea, vomiting and headache ^[1].

The label carries warnings beyond those common side effects. Among patients with acquired hypothalamic obesity and secondary adrenal insufficiency, 5% of those treated with Imcivree and no placebo patients reported serious adverse reactions related to acute adrenal insufficiency. Among patients with central diabetes insipidus, hyponatremia occurred in 6% of treated patients and 2% of placebo patients, and hypernatremia in 5% and 4% ^[1]. The label also warns about depression and suicidal ideation, serious hypersensitivity reactions including anaphylaxis, skin hyperpigmentation and new or darkened melanocytic nevi, and spontaneous penile erections. Imcivree is contraindicated in patients with prior serious hypersensitivity to setmelanotide or its ingredients, and the label states it is not indicated for general (polygenic) obesity or other types of obesity unrelated to acquired hypothalamic obesity, Bardet-Biedl syndrome or POMC, PCSK1 or LEPR deficiency ^[1].

Imcivree was already approved in the United States for adults and children aged 2 and older with syndromic or monogenic obesity due to Bardet-Biedl syndrome or POMC, PCSK1 or LEPR deficiency ^[1].

"IMCIVREE is now the first and only FDA-approved therapy for acquired HO, offering a targeted approach that addresses the underlying biology of this disease and meets a critical unmet need for patients who previously had no treatment options," said David Meeker, M.D., Rhythm's chairman, chief executive officer and president ^[1].

Why it matters for patients

People with acquired hypothalamic obesity have had no approved drug treatment, and the company describes the weight gain as caused by hypothalamic injury or dysfunction that impairs MC4R pathway signaling, which controls hunger and energy use ^[1]. The expanded approval gives patients aged 4 and older a therapy aimed at that pathway rather than at appetite hormones that GLP-1 drugs target.

The main measure in the trial was change in BMI. Ashley Shoemaker, M.D., of Vanderbilt Health, said in the announcement that patients treated with setmelanotide had meaningful reductions in BMI and hunger, though hunger was not described as a primary endpoint in the announcement ^[1].

The label directs clinicians to monitor certain patients closely: signs of acute adrenal insufficiency in patients with secondary adrenal insufficiency, serum sodium when fluid intake or hydration changes in patients with central diabetes insipidus, and full-body skin exams before and during treatment to track pigmented lesions ^[1].

Imcivree will be available for patients in the United States immediately, according to the company, which offers a support program called Rhythm InTune for education, insurance navigation at treatment initiation and injection support ^[1]. Pricing and insurance coverage for the new indication have not been disclosed.

What happens next

Rhythm is hosting a conference call at 7 p.m. ET on March 19, 2026, to discuss the approval. A webcast will be archived on the company's investor relations site about two hours after the event and will remain available for 30 days ^[1]. Whether regulators in Europe or the United Kingdom will authorize setmelanotide for acquired hypothalamic obesity has not been reported ^[1].