Soleno Therapeutics has announced the FDA approval of Vykat XR (diazoxide choline extended-release tablets) for the treatment of hyperphagia — an intense, persistent hunger — in patients with Prader-Willi syndrome (PWS).
The approval marks the first FDA-approved therapy specifically targeting hyperphagia in this rare genetic disorder.
After a series of failures in the indication, Soleno has achieved a breakthrough with the approval.
The FDA authorized the therapy for patients aged four years and older.
PWS is a complex neurodevelopmental condition that affects approximately one in 15,000 live births in the US.
According to Soleno, there are 10,000 PWS patients in the US. Globally, the condition affects more than 300,000 people.
Individuals with the condition often develop low muscle tone, short stature and intellectual and development issues.
One of its most debilitating symptoms is hyperphagia, which significantly impairs quality of life and places patients at constant risk of obesity-related complications. Until now, there have been no FDA-approved treatments addressing this hallmark symptom.
Vykat XR is an extended-release formulation of diazoxide choline, a potassium channel activator. In the pancreas, potassium channels regulate insulin secretion.
It reduces hunger signals by modulating specific neural pathways associated with satiety and metabolism.
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“Today marks a historic day for the PWS community. The FDA’s approval of Vykat XR represents a monumental step forward in addressing the longstanding unmet needs of individuals living with PWS and their families,” said Stacy Ward, CEO of the Prader-Willi Syndrome Association USA, in the approval announcement.
Soleno CEO Anish Bhatnagar, MD, stated: “The approval of Vykat XR is a significant milestone for Soleno and, most importantly, for the PWS community who have had no options to treat the most disruptive aspect of this disease.”
Since the FDA approved recombinant human growth hormone (rhGH) for PWS in 2000, multiple companies have tried — and failed — to develop a targeted treatment for hyperphagia.
Vykay XR Clinical Trial Results
Data from a randomized, placebo-controlled Phase III trial (Study 2-RWP or Study C602-RWP) support Vykat XR’s approval.
Investigators randomized patients to switch from Vykat XR to placebo during the 16‑week study period as the trial’s primary efficacy measure.
Before the randomized withdrawal phase, all participants had received double-blind and/or open-label Vykat XR treatment for an average of 3.3 years.
Participants who switched to placebo showed a statistically significant worsening of hyperphagia compared to those who continued taking Vykat XR.
The treatment was generally well-tolerated, with a safety profile consistent with previous clinical data.
Across four years of data from four open-label studies, Vykat XR has demonstrated a consistent safety profile.
The most commonly reported side effects (hypertrichosis, edema, hyperglycemia and rash) were observed in approximately 10% of patients.
The company also noted it is exploring access programs to ensure availability for eligible patients upon launch.
Based on the average weight of patients in its clinical trials, Vykat XR will cost $466,200 per year.
Soleno said it expects the treatment to be available next month.
After the late-March approval, shares of the Redwood City, California-based company jumped 37% the following day.
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The Bumpy Road to a Hyperphagia PWS Treatment
Tackling hyperphagia in PWS has been rife with failures in the past several years.
While France’s Alizé Pharma saw promising Phase II results with AZP-531 in 2016, it didn’t advance the candidate. That same year, Boston-based Zafgen’s beloranib showed efficacy in Phase III before being shelved due to safety concerns.
Saniona’s Tesomet (tesofensine + metoprolol), which received FDA Orphan Drug designation in 2021, was discontinued a year later due to funding issues.
On a more positive front, Acadia Pharmaceuticals is developing intranasal carbetocin, a therapy acquired from Levo Therapeutics for $10 million. The FDA rejected it in 2022. Acadia began a Phase III trial for the treatment in hyperphagia for PWS in November 2023.
Aardvark Therapeutics, headquartered in San Diego, is developing small-molecule therapies targeting bitter taste receptors (TAS2Rs) to modulate hunger signals in PWS via local release of gut peptides such as cholecystokinin (CCK) and glucagon-like peptide-1 (GLP-1).
The company’s lead candidate in the indication, ARD-101, is currently in a Phase III trial. Aardvark went public in February this year.
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