News Release: Rhythm Wins FDA Approval for Obesity Drug Imcivree

Rhythm Pharmaceuticals Inc., a company developing medicines for rare genetic disorders of obesity, has won FDA approval for its first product, Imcivree (setmelanotide), following a priority review. The drug is designed to restore a biological pathway that, when disrupted, can lead to constant hunger. The approval covers the treatment of three types of ultrarare early onset obesity tied to pro-opiomelanocortin (POMC), proprotein convertase subtilisin/kexin type 1 (PCSK1) and leptin receptor (LEPR) deficiencies, when confirmed by genetic testing.

In a Phase 2 trial of PWS subjects, setmelanotide failed to show a significant change in hyperphagia, therefore hyperphagia in PWS does not have an FDA indication for treatment with Imcivree. There may be instances where the drug is prescribed for individuals with PWS, but this would be an “off label” use of the medication. Expensive treatment with medications for rare diseases that are not indicated by the FDA would typically require physician justification to convince insurance companies to cover drug costs— and insurance companies might not agree to pay. There are safety considerations as well. When a medication has not completed the clinical trial process, there is incomplete safety data for the drug in certain populations. And the failed study implies that based on current data it is unlikely the drug would help in PWS.

PWSA | USA is supportive of all potential research opportunities in PWS and monitors scientific research.  We advocate for our families by supporting current research efforts and working with researchers and companies actively pursuing research to identify treatments to improve the quality of life for individuals with PWS.

If you have further questions, please call Mary Burr, Medical and Research Coordinator, at 800-926-4797 or email her at

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