Alkermes Announces Positive Phase 2 Results for Alixorexton in Narcolepsy Type 2

Alkermes plc (Nasdaq: ALKS) reported positive phase 2 results for alixorexton, a novel orexin 2 receptor agonist, in treating narcolepsy type 2 (NT2), according to a June 2026 presentation at the SLEEP meeting. The Vibrance-2 study met its dual primary endpoints, showing statistically significant improvements in wakefulness and daytime sleepiness compared to placebo, according to the company.

What Are the Key Findings From the Vibrance-2 Study?

The phase 2 trial, involving 93 adults with NT2, demonstrated that once-daily alixorexton improved wakefulness and reduced daytime sleepiness. At week eight, the 14 mg and 18 mg doses showed statistically significant gains on the Maintenance of Wakefulness Test (MWT) and Epworth Sleepiness Scale (ESS), with mean sleep latencies increasing from 6 minutes at baseline to 16 minutes and 14 minutes, respectively. ESS scores, which measure excessive daytime sleepiness, dropped to normal ranges by week eight.

Exploratory patient-reported outcomes (PROs) also showed meaningful improvements in fatigue and cognition. The 14 mg and 18 mg doses reduced fatigue scores on the PROMIS-Fatigue scale, while the 18 mg dose improved cognitive function as measured by the British Columbia Cognitive Complaints Inventory (BC-CCI). These effects persisted through the five-week open-label extension period.

How Safe Is Alixorexton in the Trial?

Alixorexton was generally well tolerated, with no serious treatment-emergent adverse events (TEAEs) reported. Common side effects included pollakiuria, insomnia, and dizziness, all classified as mild to moderate. Over 95% of participants completed the eight-week randomized double-blind period, and nearly 90% finished the 13-week open-label extension, according to the company.

What Are the Implications for Patients with Narcolepsy Type 2?

The results represent the first evidence of an orexin 2 receptor agonist improving symptoms in NT2, a condition without known orexin deficiency. “These findings highlight alixorexton’s potential as a targeted treatment for a population with significant unmet needs,” said Richard K. Bogan, M.D., a study investigator. The data build on earlier positive results from the Vibrance-1 trial in narcolepsy type 1 (NT1), which Alkermes has since advanced to phase 3.

What’s Next for Alkermes’ Development Program?

Alkermes has initiated a global phase 3 program evaluating alixorexton for NT1 and NT2, including once-daily and split-dose regimens. The company is also studying the drug in idiopathic hypersomnia (IH) through the phase 2 Vibrance-3 trial. The U.S. Food and Drug Administration (FDA) granted alixorexton Breakthrough Therapy designation for NT1 and Orphan Drug Designation for IH, while the European Commission granted Orphan Drug Designation for narcolepsy.

Why Does This Matter for the Broader Market?

Narcolepsy affects an estimated 1 in 2,000 people globally, with limited treatment options for NT2. Current therapies, such as stimulants and sodium oxybate, often fail to address all symptoms. Alkermes’ focus on the orexin system—a key regulator of wakefulness—positions alixorexton as a potential alternative. The drug’s mechanism differs from existing treatments, targeting downstream pathways rather than directly replacing orexin, according to research cited in the study.

For more details, visit Alkermes’ website or check clinical trial records at clinicaltrials.gov.