8-K: Alkermes' Alixorexton Shines in Narcolepsy Phase 2 Study

Alkermes plc announced detailed positive results from its Vibrance-1 Phase 2 study of alixorexton for narcolepsy type 1, demonstrating significant improvements in wakefulness, cognition, and fatigue.

Summary

• Alixorexton, an investigational oral, selective orexin 2 receptor (OX2R) agonist, showed clinically meaningful and statistically significant improvements in narcolepsy type 1 (NT1) symptoms.
• The Vibrance-1 Phase 2 study, involving 92 NT1 patients, evaluated once-daily doses of 4 mg, 6 mg, and 8 mg over six weeks.
• The primary endpoint, mean sleep latency (MSL) on the Maintenance of Wakefulness Test (MWT), significantly improved across all doses, with patients achieving normative wakefulness (mean sleep latency of approximately 24, 26, and 28 minutes for 4, 6, and 8 mg doses, respectively, from a baseline of ~3 minutes).
• Key secondary endpoint, Epworth Sleepiness Scale (ESS) scores, showed robust improvements, with scores sustained in the normal range (a score of 10) through week 13 from a baseline of 18.5.
• Mean weekly cataplexy rates demonstrated numerical and clinically meaningful improvements across all doses, with statistical significance achieved at the 6 mg dose (p=0.01).
• Over 40% of patients on 6 mg and 8 mg doses achieved 100% reduction in cataplexy during week six.
• Exploratory patient-reported outcomes indicated statistically significant and clinically meaningful improvements in disease severity, fatigue, and cognitive impairment, with most patients reporting mild narcolepsy severity and normalized cognition and fatigue scores at week six.
• Alixorexton was generally well tolerated across all doses, with no serious treatment-emergent adverse events (TEAEs) reported; most TEAEs were mild to moderate and often resolved early in treatment.

Sentiment

Score: 9

Explanation: The clinical trial results are overwhelmingly positive across multiple primary, secondary, and exploratory endpoints, demonstrating strong efficacy and a favorable safety profile. The drug's potential to normalize cognition and fatigue, in addition to improving wakefulness and reducing cataplexy, positions it as a potential best-in-class treatment. The clear path to Phase 3 and expansion into other hypersomnolence disorders further enhances the positive outlook.

Positives

• Alixorexton achieved normative wakefulness on the MWT across all doses tested (4 mg, 6 mg, 8 mg), with mean sleep latencies of approximately 24, 26, and 28 minutes, respectively, from a baseline of ~3 minutes.
• Statistically significant and clinically meaningful improvements were observed in mean sleep latency (p=0.01 for 4mg, p<0.0001 for 6mg and 8mg).
• Robust and clinically meaningful improvements on the Epworth Sleepiness Scale (ESS) were sustained in the normal range (score of 10) for all doses through week 13, from a baseline of 18.5 (p=0.01 for 4mg, p<0.0001 for 6mg and 8mg).
• Mean weekly cataplexy rates showed numerical and clinically meaningful improvements across all doses, with statistical significance at the 6 mg dose (p=0.01).
• More than 40% of patients at the 6 mg and 8 mg doses achieved 100% reduction in cataplexy during week six.
• Statistically significant and clinically meaningful improvements were seen in patient-reported disease severity (NSS-CT), fatigue (PROMIS-Fatigue), and cognitive impairment (BC-CCI).
• Most patients receiving alixorexton reported mild narcolepsy severity at week six.
• Mean cognitive impairment and fatigue scores fell into the lowest severity category or normal range, effectively achieving normalization.
• Alixorexton was generally well tolerated across all doses, with no serious treatment-emergent adverse events (TEAEs) reported.
• Most TEAEs were mild to moderate in severity, and common events like insomnia and blurred vision largely occurred and resolved within the first week or three days of dosing.
• No clinically meaningful changes were observed in hepatic and renal parameters, vital signs, ECGs, or ophthalmic exams.
• Over 95% of patients continued into the open-label extension, indicating good tolerability and patient interest.

Negatives

• The most common treatment-emergent adverse events (TEAEs) included pollakiuria (65% at 4mg, 50% at 6mg, 50% at 8mg), insomnia (17% at 4mg, 32% at 6mg, 33% at 8mg), salivary hypersecretion (22% at 4mg, 23% at 6mg, 29% at 8mg), urinary urgency (9% at 4mg, 18% at 6mg, 17% at 8mg), and blurred vision (9% at 4mg, 5% at 6mg, 29% at 8mg).
• One patient (4%) in the 8 mg dose group discontinued the study drug due to TEAEs.

Risks

• Initial clinical results for alixorexton may not be predictive of results of future stages of ongoing clinical studies, future clinical studies, or real-world results.
• Ongoing or future clinical studies for alixorexton may not be initiated or completed on expected timelines or at all.
• Alixorexton could be shown to be ineffective or unsafe in future studies.
• Potential changes in the cost, scope, and duration of the alixorexton development program.
• General risks and uncertainties described in the company's Annual Report on Form 10-K for the year ended December 31, 2024, and subsequent SEC filings.

Future Outlook

Alkermes plans to initiate a global Phase 3 program for alixorexton in the first quarter of 2026, based on these positive Phase 2 results. The company is also advancing Vibrance-2 (Phase 2 study in narcolepsy type 2) which has completed enrollment, and Vibrance-3 (Phase 2 study in idiopathic hypersomnia) which is currently enrolling. Additionally, Alkermes aims to advance ALKS 4510 and ALKS 7290 into first-in-human studies within 2025, with the goal of delivering novel and differentiated treatments across a broad range of disorders.

Management Comments

• Giuseppe Plazzi, M.D., Ph.D., Neurologist, Director of the Narcolepsy Center at the IRCCS of the Neurological Sciences of Bologna and Professor of Childhood Neuropsychiatry at the University of Modena and Reggio Emilia, stated: 'The detailed Vibrance-1 dataset presented at World Sleep highlights the robust efficacy of once-daily alixorexton in improving wakefulness and reducing excessive daytime sleepiness in patients with narcolepsy type 1, along with its generally well tolerated safety profile. The improvements in patient-reported outcomes, especially those related to fatigue and cognitive function, suggest that alixorexton may offer meaningful relief across a spectrum of symptoms that impact patients. These data underscore alixorexton's potential to be an important new treatment option for narcolepsy type 1 and to reduce the broader disease burden of this complex neurological disorder.'
• Richard Pops, Chief Executive Officer of Alkermes, commented: 'As we seek to unlock a new era of innovation in neuroscience, the compelling results from Vibrance-1 underscore the strength of Alkermes' orexin program. These data represent a significant new contribution to the evidence base supporting the utility of orexin 2 receptor agonists in central disorders of hypersomnolence and support exploration of the broader therapeutic potential of the class across a range of psychiatric and neurological conditions. We believe orexin-targeted therapeutics represent a significant opportunity for growth. We look forward to advancing alixorexton into phase 3 as soon as possible, and ALKS 4510 and ALKS 7290 into first-in-human studies this year, with the goal of delivering novel and differentiated new treatments across a broad range of disorders.'

Industry Context

The positive results for alixorexton position Alkermes at the forefront of a new era of innovation in neuroscience, specifically targeting central disorders of hypersomnolence. Orexin 2 receptor agonists are considered a significant opportunity for growth, as they target the master regulator of wakefulness. Alixorexton's demonstration of clinically meaningful and statistically significant impact on wakefulness, cognition, and fatigue with once-daily dosing, along with normalization of cognitive functioning and fatigue scores, suggests a potential best-in-class profile within this emerging therapeutic area.

Comparison to Industry Standards

• Alixorexton is highlighted as the 'first Orexin 2 Receptor Agonist to Demonstrate Clinically Meaningful and Statistically Significant Impact on Wakefulness, Cognition and Fatigue with Once-Daily Dosing Across a Range of Doses.'
• It is also noted as the 'first once-daily orexin 2 receptor agonist to demonstrate normalization of cognitive functioning and fatigue scores on patient-reported scales in addition to clinically meaningful improvements in severity of symptoms in the NT1 population.' This suggests a superior or more comprehensive efficacy profile compared to existing or other investigational treatments for narcolepsy type 1, which may not address cognition and fatigue to the same extent or achieve normalization.

Stakeholder Impact

• Shareholders: Highly positive due to strong clinical data, de-risking of a key pipeline asset, and potential for significant market opportunity in central disorders of hypersomnolence.
• Patients: Highly positive as alixorexton offers a promising new once-daily treatment option that addresses not only excessive daytime sleepiness and cataplexy but also critical symptoms like fatigue and cognitive impairment, potentially improving overall quality of life.
• Healthcare Providers: Positive, as the drug could provide a novel and effective treatment with a favorable safety profile for a complex neurological disorder.

Next Steps

• Initiate a global Phase 3 program for alixorexton in narcolepsy type 1 in the first quarter of 2026.
• Continue Phase 2 study (Vibrance-3) evaluating alixorexton in adults with idiopathic hypersomnia (IH).
• Advance ALKS 4510 and ALKS 7290 into first-in-human studies in 2025.
• Host an investor webcast and conference call on September 8, 2025, to discuss the data.

Key Dates

Recommendation

The detailed Phase 2 results for alixorexton are exceptionally strong, demonstrating statistically significant and clinically meaningful improvements across all primary and key secondary endpoints, including wakefulness, excessive daytime sleepiness, and cataplexy. Crucially, the drug also showed normalization of patient-reported cognitive function and fatigue, addressing a significant unmet need in narcolepsy type 1. The favorable safety profile, once-daily dosing, and clear progression to a global Phase 3 program in Q1 2026 significantly de-risk this asset. This data positions alixorexton as a potential best-in-class therapy with substantial commercial potential, warranting a strong buy recommendation for long-term investors.

Keywords

Narcolepsy Type 1, Alixorexton, ALKS 2680, Orexin 2 Receptor Agonist, OX2R, Vibrance-1, Phase 2 Study, Clinical Trial Results, Excessive Daytime Sleepiness, Cataplexy, Cognitive Impairment, Fatigue, Neuroscience, Biopharmaceutical, Alkermes