11:42 AM EDT, 07/09/2025 (MT Newswires) -- (Updates with the latest stock move in the headline and the first paragraph.)

Rhythm Pharmaceuticals ( RYTM ) shares jumped nearly 33% in recent Wednesday trading after the company said bivamelagon achieved body mass index reductions in patients in its phase 2 acquired hypothalamic obesity trial.

At 14 weeks of treatment, bivamelagon cut BMI by 9.3%, 7.7% and 2.7% from baseline in the 600 mg, 400 mg and 200 mg groups, respectively, the company said.

BMI for patients in the placebo group rose by 2.2% during the same period, the company added.

The company said bivamelagon's safety and tolerability results were consistent with melanocortin-4 receptor agonism and mechanism of action during the trial's placebo-controlled part.

During that part, one patient stopped therapy because of rectal bleeding, the company said.

The company added that there were instances of mild, localized hyperpigmentation from four patients, including one on placebo.

Rhythm Pharmaceuticals ( RYTM ) said that with the results, it plans to ask for input from US and EU regulators on a phase 3 trial design for bivamelagon.

Price: 86.52, Change: +21.38, Percent Change: +32.81