daridorexant-ad-nct07213349

NCT07213349: Daridorexant for Alzheimer's Disease

Overview

This Phase 2 clinical trial (NCT07213349) evaluates daridorexant, a dual orexin receptor antagonist, for the treatment of Alzheimer's disease[@nct07213349]. This represents a fundamentally novel therapeutic approach that targets the sleep-wake cycle to potentially modify disease progression in Alzheimer's disease, addressing a critical unmet need in neurodegeneration research.

Daridorexant (brand name Quviviq) is already FDA-approved for the treatment of insomnia disorder, where it has demonstrated efficacy in improving sleep onset and maintenance["@quviviq"]. This trial extends the application of orexin receptor antagonism to neurodegenerative disease, based on mounting evidence linking orexin system dysfunction to Alzheimer's disease pathology.

Trial Details

| Attribute | Value |
|-----------|-------|
| NCT ID | NCT07213349 |
| Phase | Phase 2 |
| Status | Recruiting |
| Intervention | Daridorexant (Dual Orexin Receptor Antagonist) |
| Condition | Alzheimer's Disease |
| Participants | 240 |
| Sponsor | Idorsia Pharmaceuticals |
| Start Date | 2024 |
| Primary Completion | 2026 |

The Orexin System: Biological Background

Discovery and Structure

NCT07213349: Daridorexant for Alzheimer's Disease

Overview

This Phase 2 clinical trial (NCT07213349) evaluates daridorexant, a dual orexin receptor antagonist, for the treatment of Alzheimer's disease[@nct07213349]. This represents a fundamentally novel therapeutic approach that targets the sleep-wake cycle to potentially modify disease progression in Alzheimer's disease, addressing a critical unmet need in neurodegeneration research.

Daridorexant (brand name Quviviq) is already FDA-approved for the treatment of insomnia disorder, where it has demonstrated efficacy in improving sleep onset and maintenance["@quviviq"]. This trial extends the application of orexin receptor antagonism to neurodegenerative disease, based on mounting evidence linking orexin system dysfunction to Alzheimer's disease pathology.

Trial Details

| Attribute | Value |
|-----------|-------|
| NCT ID | NCT07213349 |
| Phase | Phase 2 |
| Status | Recruiting |
| Intervention | Daridorexant (Dual Orexin Receptor Antagonist) |
| Condition | Alzheimer's Disease |
| Participants | 240 |
| Sponsor | Idorsia Pharmaceuticals |
| Start Date | 2024 |
| Primary Completion | 2026 |

The Orexin System: Biological Background

Discovery and Structure

The orexin system was discovered in 1998 by two independent research groups:

• Orexin A (hypocretin-1): 33 amino acid peptide
• Orexin B (hypocretin-2): 28 amino acid peptide

Orexin Receptors

Two G-protein-coupled receptors mediate orexin signaling:

Orexin-1 receptor (OX1R):

• Primarily coupled to Gq signaling
• Highly expressed in the locus coeruleus, raphe nuclei, and basal forebrain
• Mediates arousal, reward, and emotional responses

• Coupled to both Gq and Gi/o signaling
• Expressed in the hypothalamus, basal forebrain, and tuberomammillary nucleus
• Critical for sleep-wake regulation, particularly REM sleep

Orexin Functions in Normal Physiology

The orexin system serves as a master regulator of arousal:

Dysregulation of orexin signaling is implicated in multiple disorders, including narcolepsy, insomnia, depression, and neurodegenerative diseases[@selbach2017].

Orexin Dysfunction in Alzheimer's Disease

Evidence from Human Studies

Multiple lines of evidence demonstrate orexin system abnormalities in Alzheimer's disease:

Postmortem Studies:

• Reduced orexin neuron numbers in AD patients
• Decreased orexin-A and orexin-B levels in CSF
• Altered orexin receptor expression in AD brain tissue[@isaacs2023]

• Elevated orexin levels in AD CSF compared to controls
• Correlation between orexin levels and disease severity
• Association with sleep disturbances in AD patients

• Reduced orexin receptor binding in AD brains
• Altered functional connectivity in orexin circuits
• Correlations with amyloid and tau pathology

Mechanisms of Orexin Dysfunction

The relationship between orexin and AD pathology operates through multiple mechanisms:

1. Amyloid Regulation:

• Orexin modulates amyloid-beta production through effects on APP processing
• Sleep-wake cycles influence amyloid clearance via the glymphatic system
• Chronic sleep disruption increases amyloid burden[@kang2009]

• Orexin influences tau kinase and phosphatase activity
• Sleep deprivation promotes tau pathology spread
• Orexin receptor signaling affects tau aggregation kinetics

• Orexin modulates microglial activation
• Sleep disruption exacerbates neuroinflammation
• Orexin has anti-inflammatory effects in the brain

• Orexin regulates synaptic plasticity
• Sleep-dependent memory consolidation is impaired in AD
• Orexin antagonists may protect synaptic function[@kumar2020]

Sleep, Glymphatic Clearance, and AD

The Glymphatic System

The glymphatic system is a macroscopic waste clearance system in the brain:

• Discovery: First described in 2012 by Iliff et al.
• Function: Facilitates clearance of interstitial waste products
• Mechanism: Paravascular CSF flow driven by arterial pulsations
• AQP4: Aquaporin-4 water channels on astrocyte end-feet are essential[@iliff2012]

Sleep-Dependent Clearance

Sleep dramatically enhances glymphatic clearance:

Key findings:

• Glymphatic flow increases by 60% during sleep
• NREM sleep, particularly slow-wave sleep, is optimal for clearance
• Sleep deprivation reduces amyloid and tau clearance[@xie2013]

• Sleep disorders increase AD risk
• Sleep quality predicts cognitive decline
• Improving sleep may reduce AD pathology[@nedergaard2013]

Orexin's Role in Glymphatic Clearance

Orexin directly influences glymphatic function:

• Wakefulness: Glymphatic activity is suppressed during wakefulness
• Sleep transition: Orexin decline enables glymphatic activation
• Therapeutic opportunity: Blocking orexin may enhance sleep-dependent clearance

Daridorexant: Pharmacology and Clinical Profile

Molecular Characteristics

Daridorexant (ACT-541468) is a highly selective, brain-penetrant dual orexin receptor antagonist:

| Property | Value |
|----------|-------|
| Target | OX1R and OX2R |
| Affinity (OX1R) | Ki = 0.47 nM |
| Affinity (OX2R) | Ki = 0.91 nM |
| Brain penetration | High (logBB > 0) |
| Half-life | 8-10 hours |
| Bioavailability | 62% |

Clinical Efficacy in Insomnia

Phase 3 clinical trials of daridorexant in insomnia demonstrated:

Primary endpoints:

• Significant reduction in sleep onset latency (LS mean change: -7.5 to -12.4 min)
• Significant improvement in total sleep time (LS mean change: +18.2 to +32.1 min)
• Sustained efficacy at 12 months

• Does not cause next-day residual sedation
• No rebound insomnia upon discontinuation
• Preserves sleep architecture (REM and NREM stages)[@johnson2022]

Safety Profile

The established safety profile of daridorexant supports its evaluation in AD:

• Most common adverse events: headache, somnolence, nausea
• No significant next-day cognitive impairment
• Low risk of complex sleep behaviors
• No abuse potential identified

Rationale for Daridorexant in Alzheimer's Disease

Therapeutic Hypothesis

The clinical trial tests the hypothesis that blocking orexin receptors will:

Supporting Preclinical Data

Animal studies provide evidence for this approach:

Amyloid models:

• Orexin receptor blockade reduces amyloid plaques in APP/PS1 mice
• Improved spatial memory in orexin knockout mice with AD pathology
• Enhanced glymphatic clearance with orexin antagonism[@dugovic2022]

• Reduced tau phosphorylation in orexin-treated neuronal cultures
• Decreased tau propagation with orexin receptor blockade
• Neuroprotective effects in tauopathy models[@moreno2019]

Mechanistic Advantages

Targeting orexin offers several advantages over other AD therapeutic approaches:

Disease modification potential:

• Addresses upstream drivers of pathology (sleep disruption)
• Enhances endogenous clearance mechanisms
• May reduce both amyloid and tau

• Well-characterized pharmacology
• Established safety in humans
• Minimal drug-drug interactions

• Compatible with anti-amyloid antibodies
• May enhance efficacy of other AD therapeutics

Clinical Trial Design

Study Population

Inclusion criteria:

• Age 55-85 years
• Clinical diagnosis of mild-to-moderate AD (MMSE 16-26)
• Confirmed amyloid positivity (PET or CSF)
• Sleep disturbance documented by actigraphy or sleep questionnaire

• Severe medical conditions
• Active psychiatric disease
• Contraindications to MRI
• Prior orexin-targeted therapy

Treatment Arms

The trial uses a randomized, double-blind, placebo-controlled design:

| Arm | Dose | Duration |
|-----|------|----------|
| Placebo | N/A | 52 weeks |
| Daridorexant low dose | 10 mg | 52 weeks |
| Daridorexant high dose | 25 mg | 52 weeks |

Primary Endpoints

Efficacy:

• Change in ADAS-Cog (Alzheimer's Disease Assessment Scale-Cognition)
• Change in Clinical Dementia Rating Sum of Boxes (CDR-SB)

• Incidence of adverse events
• Change in vital signs and laboratory values
• MRI monitoring for ARIA (if applicable)

Secondary Endpoints

• Sleep quality (PSQI - Pittsburgh Sleep Quality Index)
• Amyloid PET change from baseline
• CSF biomarkers (p-tau, t-tau, Aβ42)
• Functional connectivity (fMRI)
• Quality of life measures

Biomarker Sub-studies

The trial incorporates extensive biomarker collection:

Imaging biomarkers:

• Amyloid PET (centiloid scale)
• Tau PET (if available)
• Structural MRI (brain volume)
• Functional connectivity

• CSF: Aβ42/40, p-tau181, t-tau, NfL
• Plasma: p-tau217, GFAP, NfL

• Polysomnography at baseline and endpoint
• Actigraphy throughout the study
• Circadian rhythm markers

Sleep and Cognitive Decline in AD

Bidirectional Relationship

Sleep disturbances and cognitive decline are bidirectionally linked in AD:

Sleep disruption increases AD risk:

• Chronic insomnia increases AD risk by 1.5-3x
• Sleep apnea is an independent risk factor
• Poor sleep quality predicts incident dementia[@brunner2020]

• Neurodegeneration affects sleep circuits
• Circadian rhythm disturbances are common
• Sleep fragmentation worsens with disease progression

Sleep-Dependent Memory Consolidation

Sleep plays a critical role in memory consolidation:

NREM slow-wave sleep:

• Hippocampal replay of day's events
• Memory transfer to neocortical networks
• Synaptic consolidation[@diekelmann2010]

• Emotional memory processing
• Procedural memory consolidation
• Neural plasticity[@rasch2013]

• Slow-wave sleep is reduced early in AD
• REM sleep behavior disorder may occur
• Memory consolidation is notably impaired

Clinical Implications

Improving sleep in AD patients may have multiple benefits:

• Enhanced quality of life
• Reduced caregiver burden
• Potential disease-modifying effects
• Improved response to other therapies

Potential Adverse Effects and Monitoring

Expected Adverse Events

Based on insomnia trials and known orexin biology:

• Headache: Most common, usually mild
• Somnolence: Next-day drowsiness (dose-dependent)
• Nausea: Generally mild and transient
• Dry mouth: Related to orexin's role in salivation

Special Considerations in AD Population

Cognitive effects:

• Monitor for paradoxical agitation
• Assess for falls risk
• Evaluate interaction with AD medications

• Orexin's role in blood pressure regulation
• Monitor for orthostatic hypotension
• Cardiac history should be reviewed

Long-Term Considerations

The 52-week treatment duration allows assessment of:

• Sustained efficacy over time
• Safety with chronic use
• Impact on disease progression
• Biomarker changes

Competitive Landscape

Other Orexin-Targeted Approaches in Development

Several orexin-targeted strategies are being explored for AD:

| Agent | Company | Target | Stage |
|-------|---------|--------|-------|
| Daridorexant | Idorsia | DORA | Phase 2 |
| Suvorexant | Merck | DORA | Phase 2 (planned) |
| Lemborexant | Eisai | DORA | Preclinical |
| ACT-541468 | Idorsia | DORA | Approved (insomnia) |

Differentiating Factors

Daridorexant may offer advantages:

• Selectivity: Higher OX2R affinity than some competitors
• Duration: Optimized half-life for nighttime dosing
• Safety: Established profile in insomnia
• Evidence: Strong mechanistic rationale in AD

Future Directions

Combination Therapy Potential

If successful, daridorexant may be combined with:

• Anti-amyloid antibodies: Lecanemab, donanemab
• Symptomatic treatments: Cholinesterase inhibitors, memantine
• Other disease-modifying agents: Tau-targeted therapies

Biomarker-Driven Approaches

Future trials may incorporate:

• Patient selection: Sleep biomarker-positive patients
• Personalized dosing: Based on sleep and biomarker responses
• Precision medicine: Genotype-guided treatment

Prevention Trials

The orexin mechanism is suitable for prevention:

• Preclinical AD: Asymptomatic individuals with sleep disorders
• At-risk populations: APOE4 carriers with sleep issues
• Long-term intervention: Multi-year treatment studies

Conclusion

The NCT07213349 trial represents a bold approach to Alzheimer's disease treatment by targeting the sleep-wake cycle through orexin receptor blockade. This strategy addresses a fundamental physiological process—sleep-dependent glymphatic clearance—that is impaired in AD and directly contributes to pathological protein accumulation.

The scientific rationale is robust: preclinical data demonstrate that orexin antagonism reduces amyloid and tau pathology, the established safety profile of daridorexant supports evaluation in an older population, and the mechanistic link between sleep and protein clearance provides a clear pathway to disease modification.

If successful, this trial could establish a new therapeutic paradigm for AD, demonstrating that enhancing endogenous brain clearance mechanisms—through improvement of sleep architecture—can slow or potentially modify disease progression. This would represent a significant advance in the treatment of Alzheimer's disease, a condition that remains one of the greatest unmet medical needs in modern medicine.

See Also

• [Alzheimer's Disease](/diseases/alzheimers-disease)
• [Sleep and Neurodegeneration](/mechanisms/sleep-neurodegeneration)
• [Orexin Signaling](/mechanisms/orexin-signaling-pathway)
• [Glymphatic System](/mechanisms/glymphatic-system)
• [Clinical Trials Dashboard](/clinical-trials/dashboard)
• [Amyloid Clearance Mechanisms](/mechanisms/amyloid-clearance)
• [Tau Pathology Mechanisms](/mechanisms/tau-pathology)

External Links

• [ClinicalTrials.gov - NCT07213349](https://clinicaltrials.gov/study/NCT07213349)
• [Quviviq FDA Approval](https://www.accessdata.fda.gov/drugsatfda_docs/nda/2022/214049Orig1s000lbl.pdf)
• [Idorsia Pharmaceuticals](https://www.idorsia.com/)

References