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Rhythm's drug shows promise in study to treat brain damage-related obesity
By Bhanvi Satija - 7/9/2025
By Bhanvi Satija
(Reuters) -Rhythm Pharmaceuticals' experimental drug helped patients with a rare form of obesity caused by brain damage cut weight in a small study, the drugmaker said on Monday, sending its shares 24% higher in early trading.
The drug, bivamelagon, was tested in a mid-stage trial to treat patients with acquired hypothalamic obesity, caused by damage to the brain's hypothalamus.
Rhythm estimates there are up to 20,000 people with the condition in the U.S. and European Union.
Eight patients who received the maximum 600 mg dose in the trial showed a reduction of 9.3% in their body mass index, a common measure of body fat based on a person's height and weight.
Patients who received a 400 mg dose showed a reduction of 7.7%, and those on the lowest 200 mg dose, a reduction of 2.7%.
The trial included 28 patients aged 12 years or older.
Rhythm said bivamelagon showed BMI reductions consistent with its lead drug, setmelanotide, sold as Imcivree in the U.S. to treat a genetic form of obesity.
Setmelanotide is also being tested to treat acquired hypothalamic obesity. Both drugs target mechanisms that regulate appetite and energy expenditure.
Wall Street analysts said data shows bivamelagon has a lower tendency for skin darkening than Imcivree and could provide a more convenient oral option for patients.
Bivamelagon could bring in over $1 billion sales by 2032, when Imcivree is expected to lose its patent, Citizens Bank analyst Jonathan Wolleben said.
In the bivamelagon study, four patients reported mild, localized skin darkening. Other side effects were mild diarrhea and nausea, and one patient discontinued treatment after suffering from rectal bleeding.
Rhythm licensed bivamelagon from LG Chem last year.
It plans to discuss with U.S. and European Union regulators the design of its late-stage study and to refine the formulation to improve tolerability.
(Reporting by Bhanvi Satija in Bengaluru; Editing by Sahal Muhammed)