Alkermes (NASDAQ:ALKS) shares fell 15% after the company released topline results from its Vibrance-2 Phase 2 trial of alixorexton in patients with narcolepsy type 2. Despite demonstrating strong efficacy, the data failed to fully convince investors.
The Dublin-based biopharma firm reported that alixorexton met both primary endpoints, showing statistically significant improvements in wakefulness and excessive daytime sleepiness compared with placebo. The once-daily oral orexin 2 receptor agonist delivered meaningful clinical benefits across all tested doses, with the 14 mg and 18 mg doses reaching statistical significance on the Maintenance of Wakefulness Test (MWT), and the 18 mg dose also hitting significance on the Epworth Sleepiness Scale (ESS).
However, despite these favorable results, investors reacted negatively, possibly due to uncertainties discussed during the company’s analyst call. Alkermes said that about 95% of participants completed the eight-week double-blind phase and moved into the ongoing open-label extension study.
“Alixorexton is the first and only oral orexin 2 receptor agonist to demonstrate efficacy in large randomized, double-blind, multi-week phase 2 studies across a range of once-daily doses in patients with narcolepsy type 1 and type 2,” said Craig Hopkinson, Chief Medical Officer at Alkermes.
The company added that the treatment was generally well tolerated across all dose levels, with most side effects rated mild to moderate. The most common adverse events included pollakiuria, insomnia, urinary urgency, dizziness, and headache.
Evercore ISI analyst Umer Raffat commented, “ALKS just hit their Ph 2 narcolepsy type 2 trial. The first objective on this study was to not fall in the Takeda -861 mold of being limited to type 1 only … and ALKS clearly accomplished that.”
Alkermes said it will present full trial data at an upcoming scientific meeting and plans to launch a global Phase 3 program for alixorexton in early 2026, aiming to advance development of what could become a first-in-class treatment for both narcolepsy subtypes.