Rhythm Pharmaceuticals reported preliminary results showing its experimental weekly injectable drug RM-718 helped reduce body weight in patients with acquired hypothalamic obesity, a rare condition caused by brain damage from tumour surgery or treatment. The Boston-based company's shares rose 5% in premarket trading. Among 11 enrolled patients, seven who completed 16 weeks of treatment saw their body mass index fall by an average of 11.6%. The drug works by activating the MC4R brain receptor, which controls hunger and metabolism. Two patients discontinued treatment due to side effects including nausea and injection site problems. Rhythm also sells setmelanotide for the same condition under the brand name Imcivree. Separately, the company reported second-quarter revenue of $71.3 million, up 46.9% from $48.5 million a year earlier.

Rhythm Pharmaceuticals reported second quarter 2026 net product revenue of $71.3 million from global sales of IMCIVREE, marking a 19% sequential increase from the first quarter. The company received over 400 patient start forms for IMCIVREE's acquired hypothalamic obesity indication from approximately 300 prescribers as of 30 June 2026, following FDA approval in March. US revenue reached $51.0 million, representing 72% of product revenue and a 38% sequential increase, driven primarily by acquired hypothalamic obesity demand. The company reported preliminary Phase 2 data showing weekly injectable MC4R agonist RM-718 achieved mean BMI reduction of 11.6% in acquired hypothalamic obesity patients after 16 weeks. Cash, cash equivalents, and short-term investments totalled approximately $330.9 million as of 30 June 2026. The company posted a net loss of $50.4 million for the quarter.

Rhythm Pharmaceuticals has published an updated diagnostic algorithm for Bardet-Biedl syndrome in the American Journal of Medical Genetics, designed to help clinicians achieve faster diagnoses using modern genetic testing. The evidence-based framework simplifies recognition of the complex, multi-organ rare disease across age groups and specialties. The new algorithm could expand identification of eligible patients for Rhythm's IMCIVREE treatment and strengthen relationships with the Bardet-Biedl syndrome community and physicians. This follows Rhythm's recent expanded indication for IMCIVREE in acquired hypothalamic obesity in the US and Europe. Whilst the algorithm may broaden patient identification, investors remain focused on Rhythm's commercial execution, persistent operating losses and reliance on setmelanotide. The company's investment case depends on converting rare genetic obesity awareness into sustainable treatment demand.