FDA Approves First Prader-Willi Syndrome Drug to Reduce Insatiable Hunger

The FDA has given the green light to Soleno Therapeutics' innovative drug, Vykat XR, which targets hyperphagia, the overwhelming hunger experienced by individuals diagnosed with Prader-Willi syndrome. Prader-Willi syndrome is a rare condition resulting from random genetic mutations and impacts approximately one in every 15,000 live births worldwide. This disease is not inherited and shows consistent prevalence across various demographics and regions. The newly approved drug, diazoxide choline, is anticipated to be available for patients as soon as next month, as detailed in a recent SEC filing, with an annual cost averaging $466,200.

Prader-Willi syndrome is usually diagnosed at birth due to a notable lack of muscle tone, causing the newborns to be described as "floppy babies." The syndrome's most challenging symptom, hyperphagia, often emerges when the child reaches the age of 8 to 12 years, though it can appear as early as four years of age. According to Soleno's CEO, Anish Bhatnagar, the low muscle tone in these infants is readily apparent, often requiring immediate medical attention. In many Western nations, affected newborns often require intensive care right from birth.

Beyond hyperphagia, Prader-Willi syndrome presents a myriad of other symptoms, including delayed motor development, insufficient growth hormone production, and various speech and behavioral problems. The intense hunger associated with the condition often proves to be the most trying for families. The strain can lead to higher divorce rates among parents and PTSD among siblings who experience the aggressive food-seeking behaviors of those affected. In many cases, families must secure their homes by locking away all food and waste, and those with the means might opt for group homes specific to Prader-Willi patients.

The mental health challenges posed by this rare disease are significant, with many patients requiring antidepressant prescriptions, which unfortunately offer limited relief. Bhatnagar describes the condition as a notably intractable rare disease, with few effective treatment options available until now. Vykat XR represents a potential breakthrough by specifically targeting the intense drive to eat, thus aiming to ease the primary burden faced by patients and their caregivers. The drug functions by engaging the ATP-dependent potassium channel and a hunger mechanism in the hypothalamus to curb appetite. It is administered as a once-daily pill.

While Soleno plans to independently commercialize Vykat XR within the United States, there remains the possibility of partnering for international distribution. The company reported holding $318 million in cash and cash equivalents by the end of 2024, indicating readiness for the drug's market launch. Analysts, such as Stifel’s Paul Matteis, project significant commercial potential for Vykat XR, suggesting it could achieve annual peak sales of at least $1.5 billion. Despite the drug not meeting its primary endpoint in Phase 3 trials, attributed to high placebo responses during the pandemic, the FDA has shown leniency in rare disease drug approvals. A subsequent study demonstrated strong statistical significance, adding to the drug's credibility and potential market success.