Rhythm Pharmaceuticals, Inc. announced the publication of previously disclosed results from its Phase 2 study of setmelanotide for the treatment of hypothalamic obesity. The data are published in the peer-reviewed journal The Lancet Diabetes & Endocrinology. Acquired hypothalamic obesity is a rare form of extreme obesity that occurs following damage to the hypothalamic region of the brain, which includes the melanocortin-4 receptor (MC4R) pathway and is responsible for controlling physiological functions such as hunger and weight regulation.

It most frequently follows the growth or surgical removal of craniopharyngioma, astrocytoma, or other rare brain tumors. Patients experience rapid weight gain, a reduction in energy expenditure, and an increase in hunger leading to severe obesity within six to 12 months following tumor resection. Rhythm enrolled 18 patients in its open-label, 16-week Phase 2 trial designed to evaluate setmelanotide in acquired hypothalamic obesity in patients with a body mass index (BMI) =95th percentile (children 6 to <18 years) or =35 kg/m2 (adults =18 years).

The primary endpoint was the proportion of patients who achieved a 5% or greater reduction in BMI after 16 weeks of treatment. Hunger was also assessed daily, as self-reported by individual patients. As previously disclosed, results demonstrated: 89% (16 of 18) of patients achieved the primary endpoint; 78% (14 of 18) of patients achieved a 10% or greater reduction in BMI at 16 weeks; Mean percent reduction in BMI was 15% from baseline; In pediatric patients (n=13), the mean (standard deviation [SD]) BMI Z score at Week 16 was 2.7 (1.3), a reduction of 1.3 (1.0) points from baseline; and Mean (SD) most hunger score at baseline was 6.6 (1.6), compared with 3.7 (2.5) at Week 16, for a reduction of ?2.9 (2.3) points or 45% for patients =12 years of age (n=11).

The publication also includes preliminary data from Rhythm?s long-term extension of the Phase 2 study that were disclosed at ObesityWeek® 2023. These data show patients with hypothalamic obesity (n=12) achieved mean BMI reduction of approximately 26% at one year on setmelanotide treatment. Consistent with prior experience, setmelanotide was generally well tolerated.

The most common adverse events (AEs) in the primary trial included nausea (61.1%), vomiting (33.3%), skin hyperpigmentation (33.3%), diarrhea (22.2%), and COVID-19 (22.2%). Two patients discontinued due to AEs and a third patient was non-compliant. There were no serious AEs, no AEs that led to study discontinuation during the trial, and no new safety concerns were observed during the long-term extension trial.

In January 2024, Rhythm announced the completion of screening for enrollment in the ongoing pivotal, Phase 3 clinical trial evaluating setmelanotide in patients with acquired hypothalamic obesity. The Company remains on track to obtain topline study results in the first half of 2025.