— 26 Abstracts Accepted Demonstrate Alkermes' Commitment to Advancing Understanding and Treatment of Narcolepsy and Idiopathic Hypersomnia —

— Detailed Positive Results from Vibrance-2 Phase 2 Study of Alixorexton, an Orexin 2 Receptor Agonist, in Patients With Narcolepsy Type 2 to be Shared in Oral Presentation —

Alkermes plc (NASDAQ:ALKS) today announced plans to present new data from its industry-leading portfolio of sleep medicine research at SLEEP 2026, the 40^th annual meeting of the Associated Professional Sleep Societies (APSS), taking place June 14-17, 2026 in Baltimore, MD. The company will present 26 abstracts, including posters featuring LUMRYZ^® (sodium oxybate) extended-release oral suspension, now part of Alkermes' sleep portfolio following the acquisition of Avadel Pharmaceuticals plc in February 2026, and alixorexton, Alkermes' novel, investigational, oral, selective orexin 2 receptor (OX2R) agonist in development for narcolepsy type 1 (NT1), narcolepsy type 2 (NT2) and idiopathic hypersomnia (IH).

The company will present detailed results from the alixorexton Vibrance-2 study, the first large phase 2 clinical trial to demonstrate positive results with an OX2R agonist in patients with NT2 (n=93). The data will be shared in an oral presentation by Richard Bogan, M.D., FCCP, FAASM, Principal of Bogan Sleep Consultants, LLC and Associate Clinical Professor at the University of South Carolina School of Medicine. Primary and secondary efficacy and safety data, and exploratory patient-reported outcomes related to fatigue and cognition from the eight-week randomized, double-blind treatment period and optional five-week open-label extension, will be presented.

Abstracts accepted for late-breaking poster presentations include:

Baseline characteristics from the phase 3 REVITALYZ^SM study evaluating the investigational use of LUMRYZ in adults with IH, for which positive topline results were recently announced; and
Two posters detailing the study designs and methods for the Brilliance Studies, a phase 3 clinical trial program evaluating the safety and efficacy of alixorexton compared to placebo in patients with NT1 and NT2.

"SLEEP 2026 is a defining moment for Alkermes as we strengthen our leadership in sleep medicine. Alkermes data being presented at SLEEP highlight the scope and scale of our scientific research in the field of sleep medicine and underscore our commitment to advancing care for people living with narcolepsy and idiopathic hypersomnia," said Craig Hopkinson, M.D. (MBChB), Chief Medical Officer and Executive Vice President, Research & Development at Alkermes. "We look forward to sharing detailed data from our alixorexton Vibrance-2 phase 2 study with clinicians, including findings related to fatigue and cognitive impairment in this population, and sharing compelling new data further characterizing the profile of LUMRYZ. As we apply our neuroscience expertise to deepen our collective understanding of narcolepsy and idiopathic hypersomnia, our goal is to advance differentiated treatment approaches for patients impacted by these complex diseases."

Additional highlights to be presented at SLEEP 2026 include:

Alixorexton clinical development

Exploratory findings from the Vibrance-1 phase 2 study evaluating the impact of alixorexton compared to placebo on quality-of-life measures in patients with NT1.

LUMRYZ real-world evidence

Posters showing real-world experience and patient survey findings from REFRESH, a prospective multicenter, real-world study in patients with narcolepsy, including those who switched to LUMRYZ from a twice-nightly oxybate and those new to oxybate treatment or returning to oxybate treatment after discontinuing a twice-nightly oxybate.

Research advancing understanding of hypersomnolence disorders

Findings from the ASPIRE survey study evaluating the impact of cognitive impairment and fatigue on work productivity and health-related quality of life in people with NT1, NT2 and IH.
Data from a claims database describing estimated prevalence of central disorders of hypersomnolence (CDoH), treatment patterns, and differences in treatment patterns across social determinants of health, including age, race, ethnicity and income level.
Findings from a survey of people with idiopathic hypersomnia featuring data regarding patient experiences and preferences for oxybate treatment.

The SLEEP 2026 abstracts are available on the SLEEP Meeting website: https://www.sleepmeeting.org/abstract-supplements/

A full list of Alkermes' presentations at SLEEP 2026 follows:

Title

Session Date and Time

Oral Presentation

Vibrance-2: A Randomized Phase 2 Study Evaluating Efficacy and Safety of the Orexin 2 Receptor Agonist Alixorexton in Patients with Narcolepsy Type 2

Session O-23

Wednesday, June 17 from 4:15-4:30 p.m.

Poster Presentations

Improvements in Quality of Life in Patients with Narcolepsy Type 1 Treated with the Orexin 2 Receptor Agonist Alixorexton

Poster #373

Monday, June 15 from 10:00-10:45 a.m.

Safety and Efficacy of the Orexin 2 Receptor Agonist Alixorexton in Patients With Narcolepsy Type 1: The Phase 2 Vibrance-1 Study

Poster #385

Monday, June 15 from 10:00-10:45 a.m.

Drug Class Utilization and Age-Related Trends in Narcolepsy and Idiopathic Hypersomnia: A Claims Database Analysis

Poster #376

Monday, June 15 from 11:00-11:45 a.m.

Polysomnographic Findings in Pediatric Patients With Narcolepsy Type 1 and Narcolepsy Type 2: A Retrospective Review

Poster #307