Rhythm Pharmaceuticals reports interim Phase 2 PWS data with 3.06% mean BMI reduction
Rhythm Pharmaceuticals released interim six-month data from an exploratory Phase 2 trial of setmelanotide in Prader-Willi syndrome, with 17 patients on active therapy and a data cut-off of May 7, 2026. The company reported mean BMI reductions, fat loss with preserved lean mass, and hyperphagia improvements, and said the results reinforce its rationale for Phase 3 development in PWS. The trial is small, open-label and ongoing for 52 weeks, so the results do not yet establish efficacy.
Key points
- Mean BMI reduction at Month 6 was -3.06% (n=17), with -3.11% in adults (n=10) and -3.00% in pediatric patients (n=7)
- Mean fat mass change was -4.19% and mean lean mass change was +0.74% across 16 patients with DEXA data
- Eight of 10 patients with moderate to severe hyperphagia achieved a 7-point or greater HQ-CT improvement
- The 52-week trial remains ongoing, with 17 patients on active therapy as of June 12, 2026
The filing
Written by AI on Nov 9, 2026, 8:53 AM ET, from this filing only. Written later: this filing was briefed after the fact, when past filings were added to the site, so the brief may be read with hindsight; the filing itself is the record of what was known on June 15, 2026.
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