Rhythm Pharmaceuticals’ setmelanotide shows efficacy in Phase 2 PWS trial

Rhythm Pharmaceuticals (RYTM) announced positive preliminary results from its exploratory Phase 2 trial of setmelanotide in patients with Prader-Willi syndrome, or PWS. The company also plans to advance setmelanotide into a Phase 3 registrational trial in PWS, pending successful completion of this Phase 2 trial. Rhythm has initiated a Part D arm in the Phase 1 trial of MC4R agonist RM-718 that will enroll up to 20 patients with PWS. Rhythm anticipates screening the first patient for this 26-week open-label trial of RM-718 in December 2025. The 52-week trial remains ongoing. Setmelanotide therapy demonstrated potential therapeutic benefit with BMI and hyperphagia reductions in patients with PWS at Month 3 and Month 6. Six of 8 patients who reached Month 3 of setmelanotide therapy achieved BMI reductions from baseline; three of 5 patients who reached Month 6 of setmelanotide therapy achieved reductions in BMI, six of 7 evaluable patients who reached Month 3 of setmelanotide therapy achieved meaningful reduction in Hyperphagia Questionnaire for Clinical Trials1 scores. Safety and tolerability results have been consistent with setmelanotide’s well-established clinical profile.