Stock Markets March 20, 2026

Rhythm Shares Rally After FDA Clears IMCIVREE for Acquired Hypothalamic Obesity

Regulatory nod expands approved uses of setmelanotide and brings first FDA-approved treatment option for acquired hypothalamic obesity to U.S. patients

By Maya Rios RYTM
Rhythm Shares Rally After FDA Clears IMCIVREE for Acquired Hypothalamic Obesity
RYTM

Rhythm Pharmaceuticals saw its stock rise after the FDA approved IMCIVREE (setmelanotide) to treat acquired hypothalamic obesity in patients aged 4 years and older, based on positive Phase 3 TRANSCEND trial results showing a statistically significant placebo-adjusted reduction in BMI. The drug will be available to U.S. patients immediately.

Key Points

  • FDA approved IMCIVREE (setmelanotide) for acquired hypothalamic obesity in patients aged 4 years and older, making it the first FDA-approved therapy for this condition.
  • Approval was based on the Phase 3 TRANSCEND trial of 142 patients, which met its primary endpoint with a -18.4% placebo-adjusted reduction in BMI; treated patients showed a -15.8% BMI change versus a +2.6% increase for placebo at 52 weeks.
  • IMCIVREE is already approved in the U.S. and Europe for certain syndromic or monogenic obesity indications and will be available to U.S. patients immediately; the company estimates roughly 10,000 people in the U.S. live with acquired hypothalamic obesity.

Shares of Rhythm Pharmaceuticals (NASDAQ:RYTM) climbed 11% on Friday morning after the U.S. Food and Drug Administration granted approval for IMCIVREE (setmelanotide) to treat acquired hypothalamic obesity. The decision designates IMCIVREE as the first and only FDA-approved therapy for this form of obesity, which is driven by hypothalamic injury or dysfunction and marked by rapid, sustained weight gain.

IMCIVREE is indicated to reduce excess body weight and to help maintain that reduction over the long term in both adults and pediatric patients aged 4 years and older with acquired hypothalamic obesity. Rhythm said the treatment will be available to patients in the United States immediately.

The approval was supported by data from the global Phase 3 TRANSCEND trial, which enrolled 142 patients diagnosed with acquired hypothalamic obesity. The trial met its primary endpoint, producing a statistically significant placebo-adjusted reduction in body mass index of -18.4%. At 52 weeks, participants receiving setmelanotide experienced an average -15.8% reduction in BMI, while those on placebo showed a +2.6% increase.

Acquired hypothalamic obesity most commonly follows tumors, their treatment, or other forms of hypothalamic injury or dysfunction. Rhythm estimates there are about 10,000 people in the United States living with the condition.

The TRANSCEND trial also identified safety findings. The most frequently reported adverse reactions among treated patients included:

  • skin hyperpigmentation
  • nausea
  • vomiting
  • headache

IMCIVREE already has approved uses in adult and pediatric patients aged 2 years and older for certain syndromic or monogenic forms of obesity. Those indications cover obesity due to Bardet-Biedl syndrome or deficiencies in Pro-opiomelanocortin, proprotein convertase subtilisin/kexin type 1, or the leptin receptor.

From a market perspective, the FDA approval represents an expansion of IMCIVREE's labeled population to include acquired hypothalamic obesity and signals immediate commercial availability in the U.S. While the patient population is estimated to be small, the designation as the first FDA-approved therapy for this condition is a regulatory milestone for the company.


Note: This report presents the trial results, labeled indications, safety profile and the company-provided estimate of patient population as stated by Rhythm Pharmaceuticals. The article does not add facts beyond those reported by the company and the TRANSCEND study outcomes noted above.

Risks

  • Adverse reactions reported in the trial included skin hyperpigmentation, nausea, vomiting and headache - safety considerations that could affect uptake among patients and prescribers.
  • The estimated U.S. patient population for acquired hypothalamic obesity is small, which may limit the immediate commercial scale of the approval and has implications for revenue expectations.
  • Market response to the approval may be influenced by real-world tolerability and prescribing patterns; the article reports only trial outcomes and company estimates without longer-term real-world data.

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