Rhythm Pharmaceuticals shares surge 16.45% premarket on positive phase 2 trial results showing setmelanotide's BMI and hyperphagia reductions in Prader-Willi syndrome patients.

Rhythm Pharmaceuticals Inc. (NASDAQ:RYTM) surged 16.45% in premarket trading following the release of preliminary phase 2 trial results for setmelanotide in treating Prader-Willi syndrome (PWS). The trial demonstrated significant reductions in BMI and hyperphagia at both 3- and 6-month intervals, with 6 of 8 patients showing BMI improvements at month 3 and 3 of 5 at month 6. Safety and tolerability remained consistent with the drug’s established profile, and 17 of 18 patients remained on active treatment. The company announced plans to advance setmelanotide to phase 3 trials if the ongoing 52-week study concludes successfully. These positive data reinforced investor confidence in the drug’s potential as a treatment for PWS, a rare genetic disorder with high unmet medical need.