ENDO 2026 data show VYKAT XR delivered sustained improvements in hyperphagia and behavioral symptoms in Prader-Willi syndrome, with benefits maintained for up to three years and regained after treatment interruption.
Written By: Samiksha Jadhav, BPharm
Reviewed By: Pharmacally Editorial Team
New data presented at ENDO 2026 strengthen the long-term evidence supporting VYKAT® XR (diazoxide choline extended-release tablets) for hyperphagia in Prader-Willi syndrome (PWS). Patients who resumed treatment after 16-week randomized withdrawal period regained improvements in hyperphagia and behavioral symptoms, while separate analyses showed sustained benefits through three years compared with real-world natural-history data.
The findings, reported by Soleno Therapeutics, a Neurocrine Biosciences company, add to the evidence supporting VYKAT XR, the first FDA-approved therapy for hyperphagia in adults and children aged four years and older with PWS.
Scientific and Clinical Basis
PWS is a rare genetic neurodevelopmental disorder characterized by hyperphagia, an intense and persistent drive to eat that can lead to severe obesity and significant medical complications. VYKAT XR is an extended-release formulation of diazoxide choline that targets pathways involved in appetite regulation.
Trial and Development Details
The latest results come from Study C614 (NCT05701774), a long-term extension study that enrolled 77 participants following a 16-week randomized withdrawal period.
Patients who restarted VYKAT XR after receiving placebo reduced Hyperphagia Questionnaire for Clinical Trials (HQ-CT) scores by a mean 4.5 points at Week 13, with improvements reaching 5.5 points at Week 26 and 6.3 points after two years. Participants who remained on continuous therapy maintained reductions of 2.7 points, 3.3 points, and 3.1 points at the same time points, respectively.
Patients who resumed treatment also showed improvements across all six domains of the Prader-Willi Syndrome Profile (PWSP), while body mass index remained relatively stable over two years of follow-up.
Additional analyses compared outcomes from the VYKAT XR clinical program with participants from the PATH for PWS Natural History Study. Among 125 treated participants and 229 PATH controls, VYKAT XR produced statistically significant improvements in HQ-CT scores at every annual assessment through Year 3 (p<0.0001), with treatment differences of 6.2 points at Year 1, 6.5 points at Year 2, and 6.2 points at Year 3.
A separate behavioral analysis comparing 105 treated participants with 182 PATH controls showed significant improvements across all six PWSP domains through three years. At Year 3, adjusted mean differences favored VYKAT XR across anxiety, rigidity and irritability, compulsivity, aggressive behaviors, disordered thinking, and depression.
Clinical Significance
Neurocrine Biosciences Chief Medical Officer Sanjay Keswani, MD, said the findings complete the Phase 3 development program and further validate VYKAT XR’s long-term clinical value, showing that benefits can be regained after treatment interruption and maintained with continued therapy.
Implications for Long-Term Disease Management
VYKAT XR received FDA approval in March 2025 and is commercially available in the United States. The latest data provide evidence that treatment effects can be sustained over multiple years and support the therapy’s role in addressing one of the most challenging symptoms of Prader-Willi syndrome.
Reference
About the Writer
Samiksha Vikram Jadhav (LinkedIn) is a B. Pharm graduate with a strong academic foundation in pharmaceutical sciences, pharmacology, and drug development. She specializes in pharma market research, with a focused interest in mergers and acquisitions, strategic partnerships, and global pharma and biotech deals. Her work centers on analyzing industry transactions, market positioning, and business strategies, translating complex developments into clear, accurate, and insightful scientific and commercial reporting.