NCT07213349: Daridorexant for Alzheimer's Disease
Overview
Mermaid diagram (expand to render)
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
These neuropeptides are produced by a small population of neurons (~70,000 in humans) located primarily in the lateral hypothalamus[@zeitzer2019]. Despite their limited numbers, orexin neurons project widely throughout the brain and regulate numerous physiological functions.
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
Orexin-2 receptor (OX2R):
- 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
The distribution of these receptors explains orexin's pleiotropic effects on wakefulness, arousal, reward processing, and autonomic function[@lord2006].
Orexin Functions in Normal Physiology
The orexin system serves as a master regulator of arousal:
Wakefulness promotion: Orexin neurons fire during active wakefulness, promoting alertness
Sleep suppression: Orexin release decreases during sleep, particularly REM sleep
Energy homeostasis: Integrates metabolic signals to coordinate feeding and arousal
Reward processing: Modulates dopamine release and reward-related behaviors
Autonomic regulation: Controls cardiovascular, respiratory, and metabolic functionsDysregulation 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]
CSF Biomarker Studies:
- Elevated orexin levels in AD CSF compared to controls
- Correlation between orexin levels and disease severity
- Association with sleep disturbances in AD patients
Neuroimaging Studies:
- 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]
2. Tau Phosphorylation:
- Orexin influences tau kinase and phosphatase activity
- Sleep deprivation promotes tau pathology spread
- Orexin receptor signaling affects tau aggregation kinetics
3. Neuroinflammation:
- Orexin modulates microglial activation
- Sleep disruption exacerbates neuroinflammation
- Orexin has anti-inflammatory effects in the brain
4. Synaptic Function:
- 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]
Clinical implications:
- 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
This mechanistic link provides the rationale for orexin receptor antagonists in AD: by inhibiting orexin signaling, daridorexant may improve sleep quality and enhance glymphatic clearance of toxic proteins[@habn2017].
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
Key differentiators:
- 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
This favorable safety profile is particularly important for AD patients, who are often taking multiple medications and are sensitive to cognitive side effects.
Rationale for Daridorexant in Alzheimer's Disease
Therapeutic Hypothesis
The clinical trial tests the hypothesis that blocking orexin receptors will:
Improve sleep quality: Reduce sleep fragmentation and improve sleep continuity
Enhance glymphatic clearance: Increase amyloid and tau removal during sleep
Reduce pathology: Lower brain amyloid and tau burden
Slow progression: Preserve cognitive function over timeSupporting 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]
Tau models:
- 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
Safety advantages:
- Well-characterized pharmacology
- Established safety in humans
- Minimal drug-drug interactions
Combination potential:
- 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
Exclusion criteria:
- 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)
Safety:
- 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
Fluid biomarkers:
- CSF: Aβ42/40, p-tau181, t-tau, NfL
- Plasma: p-tau217, GFAP, NfL
Sleep biomarkers:
- 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]
AD causes sleep disruption:
- 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]
REM sleep:
- Emotional memory processing
- Procedural memory consolidation
- Neural plasticity[@rasch2013]
Impairment in AD:
- 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
Cardiovascular effects:
- 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
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