FDA Approves First Treatment for Prader-Willi Syndrome Hunger, Marking Industry Milestone

The U.S. Food and Drug Administration (FDA) has approved Vykat XR, developed by Soleno Therapeutics, as the first treatment for the insatiable hunger associated with Prader-Willi syndrome. This landmark decision, announced on March 26, 2025, addresses a significant unmet need in the rare disease community and opens up a potentially lucrative market for the biotechnology company.

A Breakthrough for Prader-Willi Patients

Prader-Willi syndrome, affecting an estimated 10,000 to 20,000 people in the United States, is a complex genetic disorder characterized by various cognitive and behavioral symptoms. The most debilitating of these is hyperphagia, an extreme and unrelenting hunger that can lead to life-threatening complications.

Vykat XR, an extended-release formulation of diazoxide, has been approved for use in adults and children aged four years and older. This approval marks the first new therapy for Prader-Willi syndrome since the clearance of human growth hormone 25 years ago, offering hope to patients and caregivers who have long struggled with the disorder's most challenging symptom.

Unconventional Path to Approval

The journey of Vykat XR to FDA approval was far from conventional. The drug, previously known as DCCR, initially failed to meet the primary objective of its Phase 3 trial in 2020. However, Soleno Therapeutics argued that the COVID-19 pandemic had skewed the results and collaborated with the FDA to devise an innovative approach to demonstrate the drug's efficacy.

This approach involved adding a new component to the study, in which patients were randomized to either continue or discontinue Vykat treatment, with hyperphagia levels monitored over time. The success of this evaluation in September 2023 paved the way for Soleno's approval application.

Market Implications and Industry Response

The approval of Vykat XR has significant implications for both patients and the pharmaceutical industry. Analysts at Stifel estimate the market opportunity for the drug to be worth more than $1.5 billion annually, reflecting the high unmet need in Prader-Willi syndrome treatment.

Soleno Therapeutics' market value has surged past $2 billion in anticipation of this approval, despite a brief setback due to a delayed decision in November. The company has not yet disclosed the list price for Vykat XR, but industry observers are keenly awaiting this information given the potential market size.

As the pharmaceutical industry continues to focus on rare diseases and personalized medicine, the approval of Vykat XR serves as a testament to the FDA's willingness to consider flexible approaches in evaluating treatments for complex disorders with limited therapeutic options.