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Rhythm Pharma’s obesity drug shows promise for brain tumor-related weight condition

By Thomson Reuters Aug 4, 2026 | 7:30 AM

Aug 4 (Reuters) – Rhythm Pharmaceuticals said on Tuesday its experimental weekly injectable drug helped reduce body weight in patients with a rare form of ​obesity caused by damage to the brain, according ‌to preliminary data from an ongoing mid-stage study.

Shares of the Boston-based company were up 5% in premarket trading.

Here are the details:

• The company was testing the drug, RM-718, in patients with acquired ‌hypothalamic ​obesity, a condition that can develop ⁠after surgery or treatment ⁠for tumors damages the part of the brain that controls hunger and body weight. It is different from common obesity linked to diet and lifestyle.

• Among ​11 enrolled patients, the seven who completed 16 weeks of treatment saw their body mass index – a measure ⁠of body fat based on ⁠height and weight – fall by an average ​of 11.6%.

• “These encouraging results suggest that RM-718 has the potential ​to deliver clinically meaningful BMI reductions in patients” ‌with the condition, said Rhythm’s CEO David Meeker.

• RM-718 works by activating a brain receptor called MC4R, which helps control hunger and metabolism.

• The company said the level ⁠of BMI reduction was similar to results seen with its other obesity drugs, setmelanotide and bivamelagon, over a similar period.

• ⁠Two patients stopped ‌treatment due to side effects, including ⁠nausea and injection site problems, while one ​patient ‌withdrew from the trial’s extension phase.

• The ​company’s other ⁠drug for acquired hypothalamic obesity, setmelanotide, is sold under the brand name Imcivree as a once-daily injection.

• Separately, Rhythm posted second-quarter total revenue of $71.3 million, up 46.9% from $48.5 million a year earlier.

(Reporting by Kamal Choudhury in Bengaluru; Editing ​by Vijay Kishore)