The FDA has approved Soleno Therapeutics' once-daily oral therapy, Vykat XR (diazoxide choline extended-release), for the treatment of hyperphagia in patients with Prader-Willi syndrome. This marks the first FDA-approved treatment for hyperphagia in this population.
Prader-Willi syndrome (PWS) is a rare genetic disorder caused by full or partial deletions on chromosome 15, which affect gene expression regulation. It affects an estimated 50,000 individuals in the U.S. and is characterized by hypotonia in infancy, developmental delays, behavioral challenges, and, notably, hyperphagia beginning in early childhood.
Vykat XR will be available in the U.S. beginning April 2025 for patients aged four years and older with PWS and hyperphagia. The drug will be weight-dosed and is expected to cost an average of $466,200 annually, according to the company.
Hyperphagia in PWS typically develops between ages 4 and 8 and persists into adulthood, contributing to significant morbidity due to rapid weight gain, obesity, cardiovascular complications, and respiratory issues. Life expectancy in affected individuals is estimated at 21 to 29 years.
Vykat XR targets the ATP-sensitive potassium (KATP) channel pathway to reduce hyperphagia by decreasing secretion of appetite-regulating neuropeptides.
Clinical Trial Data
The FDA’s decision followed an extended review process incorporating data from a phase III randomized, placebo-controlled trial (n=127) and a subsequent randomized withdrawal study. In patients with severe hyperphagia, the drug reduced symptom severity; however, the primary endpoint of statistical significance versus placebo was not met in the overall study population.
Long-term follow-up data demonstrated sustained improvements in hyperphagia after at least one year of treatment in patients who continued therapy post-trial.
Additional Context
According to Jennifer Miller, MD, a pediatric endocrinologist at the University of Florida and principal investigator on the trials, hyperphagia in PWS presents significant challenges to daily function and caregiver burden. The approval offers the first regulatory option for addressing this core symptom.
The International Prader-Willi Syndrome Organisation has indicated plans to work with Soleno and international stakeholders to advocate for global access to the therapy.