The U.S. Food and Drug Administration has reached a historic milestone in the treatment of Prader-Willi syndrome by approving Vykat XR, manufactured by Soleno Therapeutics, marking the first-ever medication specifically designed to address the intense hunger associated with this rare condition.
The regulatory approval, announced Wednesday, enables the use of Vykat XR in both adults and children aged four and above who experience hyperphagia – the medical term for the uncontrollable hunger that characterizes Prader-Willi syndrome. The treatment comes with a significant price tag, approximately $466,000 annually based on the average patient weight from clinical trials, according to company executives.
This breakthrough addresses a critical need in treating a condition that affects between 10,000 and 20,000 Americans. Prader-Willi syndrome manifests through various cognitive and behavioral symptoms, with the most challenging being an overwhelming hunger drive that often requires caregivers to implement strict security measures around food access to prevent dangerous binge eating episodes that can lead to severe obesity and related health complications.
Until now, treatment options have been limited to supportive care measures and human growth hormone therapy to enhance muscle mass and reduce body fat. While some physicians have prescribed the
anti-seizure medication topiramate off-label to help control appetite, no FDA-approved treatments specifically targeted the hyperphagia component of the syndrome.
The path to Vykat’s approval was unconventional. The drug, previously known as DCCR, is an extended-release formulation of diazoxide, a compound traditionally used to treat low blood sugar. Initially, it failed to meet its primary endpoint in Phase 3 trials five years ago. However, Soleno Therapeutics argued that the COVID-19 pandemic had significantly impacted the trial results, pointing to marked differences in data collected before and after March 2020.
In response, Soleno collaborated with the FDA to develop an innovative solution. They added a new component to the study where patients either continued or discontinued Vykat treatment, measuring changes in hyperphagia levels over time. This approach proved successful in September 2023, leading to the subsequent approval application.
The approval process aligned with calls from experts in the field who, in a 2023 International Journal of Molecular Sciences editorial, advocated for greater flexibility in reviewing treatments for Prader-Willi syndrome. They drew parallels to the FDA’s approach with other serious conditions like ALS and Alzheimer’s disease, where regulatory flexibility has been exercised due to the critical need for treatment options.
The market response to Vykat’s development has been significant, with Soleno’s market capitalization exceeding $2 billion in anticipation of the approval. While a delayed decision in November 2023 created some investor uncertainty, market analysts remained optimistic due to the severe unmet medical need and the FDA’s involvement in designing the successful study protocol.
Financial analysts at Stifel estimate the market potential for Vykat could exceed $1.5 billion annually, citing hyperphagia as the most significant burden for patients with Prader-Willi syndrome. The approval represents a major advancement in addressing a condition that has historically proven challenging for drug developers to target effectively, offering new hope to patients and families affected by this rare genetic disorder.