Neurocrine Biosciences (NASDAQ: NBIX) has entered into a definitive agreement to acquire Soleno Therapeutics for USD 2.9 billion in cash, anchored by Vykat XR (diazoxide choline extended-release tablets), the first and only FDA-approved therapy for hyperphagia in Prader-Willi syndrome. The transaction consolidates a commercially launched orphan drug asset into Neurocrine's existing endocrinology and rare disease franchise, which already includes Ingrezza (valbenazine) and Crenessity (crinecerfont).
Neurocrine will acquire all outstanding shares of Soleno at USD 53.00 per share, representing a 34% premium to Soleno's closing price on April 2, 2026, and a 51% premium to its 30-day volume-weighted average price. The transaction is structured as an all-cash tender offer with no contingent milestone payments or royalty components disclosed. Financing will draw on cash on hand supplemented by a modest amount of pre-payable debt, and the deal carries no financing condition. Both boards have approved the merger, which is expected to close within 90 days, subject to Hart-Scott-Rodino antitrust clearance and customary conditions.
Diazoxide choline and the hypothalamic basis of hyperphagia in PWS
Vykat XR operates through activation of ATP-sensitive potassium ($K_{ATP}$) channels in hypothalamic neurons, which reduces the secretion of appetite-stimulating neuropeptides including Neuropeptide Y (NPY) and Agouti-Related Protein (AgRP). This mechanism directly addresses the neurobiological substrate of hyperphagia, the defining and most clinically consequential feature of Prader-Willi syndrome (PWS). PWS arises from loss of paternally expressed gene function in the chromosome 15q11-q13 region, producing a neurodevelopmental disorder characterized by dysregulated satiety signaling, cognitive impairment, and a range of behavioral and metabolic comorbidities. Hyperphagia in this population is chronic and life-threatening, driving morbidity through obesity, type 2 diabetes, cardiovascular disease, and mortality events including gastric rupture and accidental death from food-seeking behavior.
Prior to Vykat XR's FDA approval in March 2025, no approved pharmacological intervention existed specifically targeting hyperphagia in PWS. The drug is indicated for adults and pediatric patients aged four years and older, and Soleno's pivotal Study C602 — a randomized withdrawal design — demonstrated statistically significant improvement on the Hyperphagia Questionnaire for Clinical Trials (HQ-CT) versus placebo at both 26 weeks (p < 0.001) and 52 weeks (p ≤ 0.003).