FDA Approves First Drug for Excess Hunger in Prader-Willi Syndrome

The FDA has approved Vykat XR (diazoxide choline) tablets to treat hyperphagia (excess hunger) in adults and children 4 years of age and older with Prader-Willi syndrome (PWS), a rare genetic disorder.

Susan Hedstrom

“This approval is a testament to the power of persistence, science, and advocacy,” Susan Hedstrom, executive director of the Foundation for Prader-Willi Research, said in a news release. “For years, families and researchers have worked towards a treatment option that truly addresses the complexities of PWS. Today, we take a major step forward in changing the future for individuals navigating hyperphagia associated with PWS.”

Prader-Willi is caused by an abnormality in the gene expression on chromosome 15. A key characteristic is a sensation of hunger accompanied by food preoccupations, an extreme drive to consume food and food-related behavior problems. The disorder can also cause muscle weakness, developmental delays, cognitive impairment and behavioral problems. It affects about one in every 15,000 live births.

Developed by Soleno Therapeutics, Vykat XR is a proprietary extended-release dosage form containing diazoxide choline, the crystalline salt of diazoxide and is administered once daily.

Vykat XR will be available beginning in April 2025 with a list price of $5.92 per milligram. Dosage is by each patient’s weight. The average baseline weight of patients in the company’s clinical was 61 kg, which would equal an average annual cost of $466,200 for the first year, this includes the required titration to reach maintenance dose, according to a company spokesperson.

The company has launched a patient support program, Soleno One, which provides education and resources, as well as support throughout the insurance process. The program includes a $0 copay for commercially insured patients, which company officials said account for about one-third of the payer mix with Prader-Willi. Patients with Medicare account for about 31%and patients with Medicaid account for about 33%

The FDA approval was based on a well-controlled study and safety data from the comprehensive clinical development program. Efficacy was established during the 16-week randomized withdrawal study period of Study 2-RWP, a phase 3 placebo-controlled trial. Investigators found that patients who were randomized to switch to placebo demonstrated a statistically significant worsening of hyperphagia compared with individuals who remained on Vykat XR.

The safety profile was established with more than four years of data across four double-blind and/or open-label studies. The primary safety analyses are based on Study 1 (Study C601), and the most common adverse reactions occurring in greater than or equal to 10% of patients included hypertrichosis (excessive hair growth), edema, hyperglycemia (high glucose levels) and rash.

Diabetes is common among patients with Prader-Willi syndrome, but researchers said hyperglycemia adverse events were generally manageable with adjusting the dosage of Vykat XR or with oral antihyperglycemic agents.