Alkermes Announces Positive Phase 1b Results Demonstrating Clinical Proof-of-Concept for ALKS 7290 in Adults With Attention-Deficit Hyperactivity Disorder (ADHD)

— ALKS 7290 is the First Orexin 2 Receptor Agonist to Demonstrate Clinically Meaningful Improvements in ADHD Symptoms in Adults —

— ALKS 7290 Was Generally Well Tolerated at All Doses Tested in Healthy Volunteers and Adults With ADHD —

— Phase 2 Study of ALKS 7290 in Adults With ADHD is Enrolling, Data Expected in 2027 —

DUBLIN, September 21, 2026--Alkermes plc (Nasdaq: ALKS) today announced positive topline results from a phase 1 proof-of-concept study evaluating ALKS 7290, the company's novel, investigational orexin 2 receptor (OX2R) agonist in development for the treatment of attention-deficit hyperactivity disorder (ADHD). The study evaluated the safety and tolerability (primary objective) and pharmacokinetics (PK) and pharmacodynamics (PD) of ALKS 7290 in healthy volunteers (n=88) and in adults with ADHD (n=50). In the phase 1 study, ALKS 7290 was generally well tolerated at all doses tested in healthy volunteers and adults with ADHD. In adult participants with ADHD, ALKS 7290 demonstrated dose-dependent, clinically meaningful improvements on exploratory endpoints evaluating change from baseline on established clinical scales, the Adult ADHD Investigator Symptom Rating Scale (AISRS) and Clinical Global Impression-Severity Scale (CGI-S), at day 14 of treatment. These findings represent the first clinical evidence of the effects of an orexin receptor agonist in the treatment of ADHD and further support the dose range selected for the ongoing phase 2 study evaluating the efficacy and safety of ALKS 7290 in adults with ADHD.

"ADHD is a common mental health condition that can have profound effects on multiple aspects of daily life, including academic achievement, career success, relationships and overall physical and emotional well-being. For many patients today, there remains a critical need for differentiated therapies that provide strong, well-tolerated efficacy," said Greg Mattingly, M.D., Founding Partner of St. Charles Psychiatric Associates, President at Midwest Research Group and Associate Clinical Professor in the Department of Psychiatry at the Washington University School of Medicine. "These data provide early evidence supporting the potential of the orexin pathway to influence the brain's neural networks that are linked to ADHD and suggest that ALKS 7290 could represent a meaningful new therapeutic approach for patients."

The phase 1b study enrolled 50 adults with ADHD in a double-blind, placebo-controlled, parallel-group trial with two cohorts. Following a two-week washout of existing ADHD medications, participants were randomized (4:1, active:placebo) within each cohort to receive ALKS 7290 (total daily dose of 20 mg (n=20) or 50 mg (n=20), administered in split doses) or placebo (n=10) for 14 days of inpatient treatment. In addition to safety, tolerability and PK and PD effects, the study evaluated change from baseline across a range of exploratory endpoints to begin to characterize the effects of ALKS 7290 on symptoms of ADHD. The study was not designed or powered to detect statistically significant differences between treatment groups.