The TRANSCEND Trial: Setmelanotide Reduced BMI in Acquired Hypothalamic Obesity, NEJM Data Show

A phase 3 trial testing setmelanotide in acquired hypothalamic obesity, a rare condition caused by damage to the brain's hypothalamus rather than by a genetic mutation, was published in the New England Journal of Medicine on July 9, 2026. The trial, named TRANSCEND, was sponsored by Rhythm Pharmaceuticals and is registered on ClinicalTrials.gov as NCT05774756.

Acquired hypothalamic obesity most often follows a brain tumor such as craniopharyngioma, its surgical treatment, radiation, or another injury to the hypothalamus, the brain region that regulates hunger and energy balance. It is distinct from the genetically defined forms of obesity, such as POMC, PCSK1, or LEPR deficiency and Bardet-Biedl syndrome, for which setmelanotide was first approved. Setmelanotide is a melanocortin-4 receptor (MC4R) agonist, designed to restore appetite-regulating signaling downstream of the hypothalamic pathway that these conditions disrupt.

The trial enrolled 120 participants, with a mean age of 19.9 years and ages ranging from 4 to 66, at sites in multiple countries. Participants were randomly assigned in a 2:1 ratio to receive setmelanotide, dosed at 1.5 to 3.0 mg once daily by subcutaneous injection after a dose-escalation period, or a matching placebo, for 52 weeks. The primary endpoint was the mean percent change in BMI from baseline to week 52.

The least-squares mean change in BMI was -16.5% (95% confidence interval, -19.3 to -13.8) in the setmelanotide group and 3.3% (95% CI, -0.6 to 7.2) in the placebo group, a difference the trial authors reported as statistically significant (p<0.001). A secondary endpoint, the weekly average of participants' maximal daily hunger score, also improved more with setmelanotide than placebo (least-squares mean change -2.73 versus -1.45, p=0.009).

Adverse events were reported in 100% of participants who received setmelanotide and 90% of those who received placebo. Serious adverse events occurred in 28% of the setmelanotide group versus 8% of the placebo group. The most common adverse events with setmelanotide were skin hyperpigmentation, nausea, vomiting, and headache, consistent with effects already described on the drug's label for its other approved indications.

In a July 8, 2026 statement announcing the publication, Rhythm Pharmaceuticals said the trial showed a 19.8 percentage-point placebo-adjusted difference in BMI change, with 80% of setmelanotide-treated participants achieving at least a 5% BMI reduction. Christian Roth, a pediatric endocrinologist and the trial's principal investigator, said in the statement that "patients with acquired hypothalamic obesity and their families face an urgent need for effective treatment options," and that "the results of the TRANSCEND trial demonstrate meaningful and consistent reductions in body mass index as well as improvements in hunger." David Meeker, the company's chairman, president and chief executive, said the NEJM publication "underscores both the strength of the clinical evidence and the potential positive impact of setmelanotide for people living with acquired hypothalamic obesity."

Setmelanotide, sold as Imcivree, is an FDA-approved, prescription-only peptide administered under medical supervision. Its U.S. label already covers acquired hypothalamic obesity in patients 4 years of age and older in addition to the genetically defined conditions for which it was originally approved. This publication reports the full peer-reviewed phase 3 data behind that indication rather than a new regulatory action. The trial results do not apply to obesity generally, and this reporting is not medical or dosing guidance.