Alkermes has reported positive detailed results from the phase 2 Vibrance-2 study of alixorexton in adults with narcolepsy type 2, showing significant improvements in wakefulness and excessive daytime sleepiness compared with placebo.
The findings, presented at SLEEP 2026 in Baltimore, mark the first large phase 2 study of an orexin 2 receptor agonist to demonstrate clinically meaningful and statistically significant benefits in narcolepsy type 2, a condition in which orexin deficiency is not typically seen. Alixorexton is an investigational once-daily oral selective orexin 2 receptor agonist currently in development for narcolepsy type 1, narcolepsy type 2 and idiopathic hypersomnia.
Vibrance-2 was a randomised, double-blind, placebo-controlled dose-ranging trial involving 93 adults with narcolepsy type 2. Participants received alixorexton at doses of 10 mg, 14 mg or 18 mg, or placebo, once daily for eight weeks, followed by a five-week open-label extension.
The drug met both dual primary endpoints at week eight. On the Maintenance of Wakefulness Test, alixorexton improved mean sleep latency compared with placebo across all doses, with statistically significant effects at 14 mg and 18 mg. Participants had a baseline mean sleep latency of around six minutes, rising to approximately 14 to 16 minutes at week eight depending on dose.
Alixorexton also improved excessive daytime sleepiness as measured by the Epworth Sleepiness Scale, with clinically meaningful benefits across all doses and statistical significance at the 18 mg dose. By week 13, mean Epworth scores across all dose groups were within the normal range.
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Exploratory patient-reported outcomes suggested additional benefits for fatigue and cognition. Improvements in fatigue and cognitive complaints emerged as early as week two and were sustained through week 13.
Alixorexton was generally well tolerated across all doses, with no serious treatment-emergent adverse events reported. The most common adverse events included pollakiuria, insomnia, urinary urgency, dizziness and headache. More than 95% of participants completed the double-blind phase.
Alkermes has already launched a global phase 3 programme in narcolepsy type 1 and type 2. If confirmed in larger trials, alixorexton could become an important new treatment option for central disorders of hypersomnolence.
This news item has been summarised using AI and checked by humans before publication.
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