Alkermes Plc Phase‑2 Narcolepsy Trial Success and Market Reaction
Alkermes Plc (NASDAQ:ALKS) saw its shares rise 3.1% on Wednesday following the release of positive data from the phase‑2 Vibrance‑2 study of alixorexton, an investigational oral selective orexin‑2 receptor agonist for narcolepsy type 2. The trial enrolled 93 adult participants and met both primary endpoints, delivering statistically significant and clinically meaningful improvements in wakefulness and excessive daytime sleepiness compared with placebo at week eight.
The once‑daily alixorexton demonstrated dose‑dependent enhancements on the Maintenance of Wakefulness Test (MWT) and the Epworth Sleepiness Scale (ESS). Baseline mean sleep latency was approximately six minutes. At week eight, mean sleep latencies increased to roughly 16 minutes for the 10 mg dose and to about 14 minutes for both the 14 mg and 18 mg doses. The 14 mg and 18 mg doses achieved statistical significance on the MWT, while the 18 mg dose also reached statistical significance on the ESS. Baseline mean ESS score was around 17, indicating severe excessive daytime sleepiness; by week eight, the majority of participants across all dose groups reported normal or mild levels of sleepiness.
Patient‑reported wakefulness benefits were sustained throughout a five‑week open‑label extension, and exploratory outcomes showed clinically meaningful improvements in fatigue and cognition. Safety data indicated that alixorexton was generally well tolerated at all dose levels, with no serious treatment‑emergent adverse events reported. The most frequently observed adverse events were pollakiuria, insomnia, micturition urgency, dizziness, and headache.
Treatment adherence was high, with more than 95% of participants completing the eight‑week double‑blind period and nearly 90% completing the subsequent 13‑week open‑label extension. Alixorexton is also being developed for narcolepsy type 1 and idiopathic hypersomnia.
Market Impact: The trial’s success prompted a 3.1% increase in Alkermes’ share price, reflecting investor optimism about the drug’s potential to address unmet needs in narcolepsy and related sleep disorders.