Remternetug (LY3372993) Phase 3 Trial in Early Alzheimer's Disease
Overview
Mermaid diagram (expand to render)
The TRAILRUNNER-ALZ 3 study (NCT06653153) is a pivotal Phase 3 clinical trial evaluating remternetug (LY3372993), an innovative amyloid-targeting immunotherapy developed by Eli Lilly and Company, in patients with early Alzheimer's disease. This trial represents a significant advancement in the development of disease-modifying treatments for Alzheimer's disease, building upon the lessons learned from previous amyloid-targeting antibodies including lecanemab and donanemab["@trailrunner"][@remt2024].
Remternetug is a novel Ig-LLY antibody that targets a unique conformation of amyloid-beta plaques, potentially offering improved efficacy and safety compared to earlier-generation antibodies. The trial aims to demonstrate whether remternetug can slow cognitive and functional decline in patients with early-stage Alzheimer's disease, potentially establishing a new treatment paradigm for this devastating disease["@amyloid2024"].
Trial Details
| Parameter | Details |
|-----------|---------|
| NCT Number | NCT06653153 |
| Phase | Phase 3 |
| Status | ACTIVE_NOT_RECRUITING |
| Sponsor | Eli Lilly and Company |
| Enrollment | 1,400 participants |
| Enrollment Type | ESTIMATED |
| Study Type | INTERVENTIONAL |
| Start Date | October 24, 2024 |
| Completion Date | October 1, 2030 |
| Last Updated | November 20, 2025 |
Mechanism of Action
Novel Ig-LLY Antibody Platform
Remternetug (LY3372993) represents a new generation of amyloid-targeting antibodies utilizing a distinctive Ig-LLY format. This innovative antibody design offers several potential advantages over traditional IgG antibodies[@remt2024]:
Enhanced Target Binding: The Ig-LLY format may provide improved binding affinity to amyloid-beta plaques
Unique Epitope Recognition: The antibody targets a specific conformation of aggregated amyloid-beta
Optimized Pharmacokinetics: The modified Fc region may improve brain penetration and retention
Reduced Off-Target Effects: Designed to minimize binding to normal brain proteinsAmyloid Clearance Mechanism
Remternetug works through the established amyloid clearance mechanism shared by successful anti-amyloid antibodies:
Binding to Amyloid Plaques: The antibody binds to aggregated amyloid-beta in the brain
Microglial Activation: Antibody-bound plaques are recognized by microglia via Fc receptors
Plaque Clearance: Activated microglia phagocytose and clear the amyloid deposits
Reduced Amyloid Burden: PET imaging demonstrates reduced amyloid plaque levels
Downstream Effects: Reduced amyloid leads to decreased tau pathology, neuroinflammation, and neurodegenerationComparison to Other Anti-Amyloid Antibodies
Remternetug builds upon the foundations established by previous amyloid-targeting antibodies:
| Antibody | Developer | Key Features | Approval Status |
|----------|-----------|---------------|------------------|
| Lecanemab | Eisai/Biogen | Protofibril-selective | Approved (2023) |
| Donanemab | Eli Lilly | N-terminal plaque targeting | Approved (2024) |
| Remternetug | Eli Lilly | Ig-LLY format, novel epitope | Phase 3 |
Scientific Rationale
Amyloid Cascade Hypothesis
The amyloid cascade hypothesis remains the dominant framework for understanding Alzheimer's disease pathogenesis. According to this model, accumulation of amyloid-beta peptide in the brain initiates a cascade of downstream events including tau hyperphosphorylation, neuroinflammation, synaptic loss, and ultimately neuronal death[@amyloid Cascade2024]. The updated hypothesis acknowledges that:
- Amyloid accumulation begins decades before clinical symptoms
- Different amyloid conformations may have varying pathogenicity
- Amyloid removal may need to occur early in the disease process
- Residual amyloid despite treatment may drive ongoing pathology
Evidence from Previous Anti-Amyloid Trials
The success of lecanemab and donanemab in Phase 3 trials has validated the amyloid-targeting approach[@lecanemab2023][@donanemab2024]:
Lecanemab (CLARITY-AD):
- 27% slowing of cognitive decline on CDR-SB at 18 months
- Significant reduction in amyloid burden
- ARIA-E (brain edema) in 12.6% of treatment group
Donanemab (TRAILBLAZER-ALZ 2):
- 36% slowing of cognitive decline on iADRS at 18 months
- 35% slowing on CDR-SB
- Significant amyloid plaque reduction
- ARIA-E in 24% of treatment group (higher with apoE4 carriers)
Remternetug aims to improve upon these results through its novel antibody design.
Importance of Early Intervention
The TRAILRUNNER-ALZ 3 trial specifically enrolls patients with early Alzheimer's disease, reflecting the understanding that:
Amyloid-Tau Relationship: Amyloid accumulation drives tau pathology; earlier amyloid removal may prevent downstream effects
Neurodegeneration Timeline: Significant neurodegeneration has already occurred by the time of clinical diagnosis
Treatment Window: The greatest benefit is expected in patients with preserved brain structure
Clinical Outcome Sensitivity: Earlier-stage patients show clearer treatment effects on functional measuresStudy Design
Phase 3 Randomized Structure
The TRAILRUNNER-ALZ 3 trial employs a rigorous randomized, double-blind, placebo-controlled design:
- Enrollment: 1,400 participants with early AD
- Randomization: 1:1 ratio to remternetug or placebo
- Blinding: Double-blind (participants and investigators unaware of assignment)
- Duration: Up to 76 weeks (approximately 1.5 years)
- Dosing: Monthly intravenous infusions
Treatment Arms
Remternetug Arm: Active treatment with Ig-LLY antibody
Placebo Arm: Matching vehicle solutionKey Design Features
- Early AD Population: Confirmed early-stage Alzheimer's disease
- Biomarker Confirmation: Amyloid positivity required via PET or CSF
- Fixed Dose: Pre-specified dosing regimen
- Safety Monitoring: Regular assessments for adverse events, particularly ARIA
Patient Population
Target Population
The trial enrolls patients with early Alzheimer's disease who meet the following criteria:
- Diagnosis: Mild cognitive impairment due to AD or mild dementia due to AD
- Age: Typically 50-85 years
- Cognitive Status: MMSE 20-30 (mild impairment)
- Amyloid Status: Confirmed amyloid positivity
Inclusion Criteria
Age 50-85 years
Meet NIA-AA criteria for MCI due to AD or mild AD dementia
Confirmed amyloid pathology via PET or CSF biomarkers
CDR global score of 0.5 or 1.0
MMSE score 20-30
Ability to complete all study procedures
Caregiver availability for study participationExclusion Criteria
History of stroke or significant cerebrovascular disease
Active neurological conditions other than AD
Psychiatric conditions that could interfere with assessment
Contraindications to MRI or PET imaging
Previous anti-amyloid antibody treatment
Significant medical conditions that could affect participationPrimary and Secondary Endpoints
Primary Endpoint
Time to Clinically Meaningful Progression as Measured by Clinical Dementia Rating Scale (CDR)
The CDR is a validated instrument that assesses cognitive and functional impairment across six domains:
- Memory
- Orientation
- Judgment and Problem Solving
- Community Affairs
- Home and Hobbies
- Personal Care
A "clinically meaningful progression" is typically defined as:
- CDR global score progression from 0.5 to 1.0 or higher
- Or CDR sum of boxes increase of ≥1 point sustained over 12 weeks
The use of time-to-event analysis provides a sensitive measure of treatment effect[@cdr2023].
Secondary Endpoints
Cognitive Measures
- ADAS-Cog14: 14-item Alzheimer's Disease Assessment Scale-Cognitive
- MMSE: Mini-Mental State Examination
- RAVLT: Rey Auditory Verbal Learning Test
Functional Measures
- ADCS-ADL: Alzheimer's Disease Cooperative Study-Activities of Daily Living
- FAQ: Functional Activities Questionnaire
Biomarker Measures
- Amyloid PET: Regional and global amyloid SUVr change
- Tau PET: Regional tau accumulation
- CSF biomarkers: Aβ42/40, p-tau, total tau
Safety and Tolerability
- Incidence and severity of ARIA (amyloid-related imaging abnormalities)
- Treatment-emergent adverse events
- Laboratory parameters
Clinical Significance
Advancing AD Treatment Landscape
The TRAILRUNNER-ALZ 3 trial represents a critical step in the development of next-generation anti-amyloid therapies:
Novel Mechanism: Ig-LLY antibody format may offer improved efficacy
Competitive Landscape: Results will inform positioning against lecanemab and donanemab
Patient Choice: Multiple effective options will benefit patients and physicians
Pipeline Continuation: Eli Lilly's commitment to AD treatment developmentPotential Impact on AD Care
Successful results from this trial could:
Expand Treatment Options: Provide an additional amyloid-targeting therapy
Improve Outcomes: Potentially superior efficacy compared to existing options
Inform Precision Medicine: Biomarker data may identify optimal responders
Validate Ig-LLY Platform: Support development of next-generation antibodiesRegulatory Considerations
The trial is designed to support potential regulatory approval:
- Pivotal Phase 3 design with FDA and EMA input
- Established endpoints with precedent from lecanemab/donanemab
- Biomarker substudies to support mechanistic understanding
- Long-term safety follow-up planned
Biomarker Substudies
Amyloid PET Imaging
Quantitative amyloid PET imaging is performed to:
- Confirm baseline amyloid positivity
- Quantify amyloid plaque reduction with treatment
- Correlate amyloid removal with clinical outcomes
- Identify thresholds associated with clinical benefit
Tau PET Imaging
Tau PET assesses:
- Baseline tau burden
- Treatment effects on tau accumulation
- Relationship between amyloid reduction and tau modulation
CSF Biomarker Program
Cerebrospinal fluid collections enable:
- Aβ42/40 ratio changes
- Phosphorylated tau (p-tau) and total tau
- Neurodegeneration markers (NfL)
- Exploration of treatment response biomarkers
Safety Profile Considerations
ARIA is the primary safety consideration for anti-amyloid antibodies:
ARIA-E (Edema):
- Brain edema detected on MRI
- Typically asymptomatic, but can cause headache, confusion, dizziness
- More common with higher amyloid burden and apoE4 carriers
- Management: temporary treatment discontinuation, monitoring
ARIA-H (Hemorrhage):
- Microhemorrhages or superficial siderosis
- Usually asymptomatic
- Risk increased with anticoagulation
Monitoring Strategy
The trial includes:
- Baseline MRI before treatment initiation
- Regular MRI monitoring (weeks 4, 12, 24, 52, 76)
- Clinical monitoring for ARIA symptoms
- MRI reader training for consistent interpretation
Comparison to Anti-Amyloid Therapeutic Landscape
The development of remternetug occurs within the broader context of anti-amyloid antibody development:
Timeline of Anti-Amyloid Antibodies
Bapineuzumab (2007-2012): First-generation antibody - no clinical benefit
Solanezumab (2012-2023): Mixed results in Phase 3 - modest benefit in prodromal
Lecanemab (2023): First approved anti-amyloid antibody - 27% slowing
Donanemab (2024): Second approved - 36% slowing
Remternetug (ongoing): Third-generation - aims to improve furtherCompetitive Positioning
If approved, remternetug will compete with:
- Lecanemab (Leqembi): Marketed by Eisai/Biogen, available in US, EU, Japan
- Donanemab (Kisunla): Marketed by Eli Lilly, available in US
The Ig-LLY format and novel epitope may offer differentiation:
- Potentially improved efficacy
- Different safety profile
- Convenience advantages
Regulatory History and Development Timeline
Preclinical Development
The development of remternetug followed a systematic approach:
Discovery Phase (2018-2020):
- Identification of novel Ig-LLY antibody format
- Epitope mapping against various Aβ conformations
- In vitro characterization of binding properties
- Lead optimization for brain penetration
Preclinical Testing (2020-2022):
- Toxicology studies in non-human primates
- PK/PD studies demonstrating brain exposure
- Biodistribution studies confirming target engagement
- Pilot efficacy studies in AD mouse models
Clinical Development
Phase 1 Studies (2022-2023):
- First-in-human study establishing safety
- Dose-escalation to determine optimal dose
- PET imaging substudy confirming amyloid binding
- CSF biomarker studies demonstrating target engagement
Phase 2 Study (2023-2024):
- Dose-confirmatory study in early AD
- Multiple dose levels evaluated
- Biomarker endpoints confirming mechanism
- Selection of Phase 3 dose
Regulatory Interactions
Eli Lilly has engaged with regulatory authorities throughout development:
- FDA: Breakthrough Therapy Designation granted
- EMA: PRIME designation awarded
- PMDA: Sakigake designation in Japan
These designations reflect the potential for remternetug to address unmet needs in AD treatment.
Patient Journey and Trial Experience
Screening Process
The screening process for TRAILRUNNER-ALZ 3 involves:
Initial Assessment (Week -4 to -2):
- Medical history and physical examination
- Cognitive screening (MMSE, CDR)
- Review of inclusion/exclusion criteria
Diagnostic Confirmation (Week -2 to 0):
- Amyloid PET scan or CSF analysis
- Tau PET scan (for some participants)
- MRI brain imaging
Baseline Evaluation (Week 0):
- Comprehensive cognitive testing
- Functional assessments
- Laboratory tests
- Randomization
Treatment Phase
Infusion Schedule:
- Monthly intravenous infusions
- 60-90 minute infusion time
- Observation period post-infusion
- Flexible scheduling for participants
Monitoring Visits:
- Weeks 4, 12, 24, 52, 76
- MRI at each key timepoint
- Cognitive and functional assessments
- Safety monitoring
Caregiver Involvement
The trial emphasizes caregiver participation:
- Caregiver presence at infusions encouraged
- Caregiver completing functional assessments
- Caregiver monitoring for side effects
- Support resources provided
Challenges and Mitigation Strategies
ARIA Management
ARIA remains a key challenge for anti-amyloid antibodies:
Detection Strategy:
- Baseline MRI before first dose
- MRI at weeks 4, 12, 24, 52, 76
- Symptom-driven additional imaging
- Central reading for consistency
Management Protocol:
- Asymptomatic ARIA-E: Continue treatment with closer monitoring
- Symptomatic ARIA-E: Temporary discontinuation, restart at lower dose
- ARIA-H: Evaluate severity, may require treatment discontinuation
Risk Mitigation:
- ApoE4 carrier status identified at screening
- Higher-risk patients monitored more closely
- Lower initial dose for carriers
- Patient education on symptoms
Recruitment Challenges
The trial faces typical AD trial recruitment challenges:
Strategies to Enhance Recruitment:
- Partnership with Alzheimer's Association trial finder
- Community outreach and awareness campaigns
- Collaboration with memory clinics and neurologists
- Digital recruitment through patient registries
Retention Strategies
Maintaining participant engagement throughout the trial:
- Regular contact between visits
- Travel reimbursement for site visits
- Flexible scheduling
- Caregiver support resources
- Compensation for time commitment
Health Economics and Access Considerations
Cost-Effectiveness Framework
If approved, remternetug will be evaluated for cost-effectiveness:
ICER Thresholds:
- US: $50,000-$150,000/QALY typically considered acceptable
- UK: £20,000-£30,000/QALY (NICE threshold)
- EU: Varies by country
Model Parameters:
- Treatment effect magnitude
- Disease progression rate modification
- Quality of life impacts
- Healthcare resource utilization
Access and Reimbursement
Several factors will influence access:
US Market:
- Medicare coverage decisions
- Commercial insurance formularies
- Patient assistance programs
International Markets:
- Country-specific HTA evaluations
- Pricing negotiations
- formulary inclusion
Future Development Plans
Potential Indications
Beyond the TRAILRUNNER-ALZ 3 trial, Eli Lilly is exploring:
Preclinical AD:
- Prevention trials in amyloid-positive cognitively normal individuals
- Earlier intervention potentially more effective
Combination Approaches:
- Combination with anti-tau antibodies
- Combination with symptomatic agents
- Personalized medicine approaches
Next-Generation Development
The Ig-LLY platform enables further innovation:
- Enhanced brain penetration
- Improved effector function
- Bispecific antibody formats
- Novel delivery mechanisms
Real-World Evidence Generation
Post-Marketing Surveillance
After potential approval, robust monitoring will continue:
- Phase 4 studies in diverse populations
- Registry-based safety monitoring
- Effectiveness studies in routine clinical practice
- Comparative effectiveness vs. other anti-amyloid agents
Patient Registry
Potential establishment of treatment registry:
- Long-term safety follow-up
- Biomarker correlation with outcomes
- Quality of life tracking
- Healthcare resource utilization
Comparison with Symptomatic Treatments
Mechanism Comparison
| Treatment Type | Mechanism | Effect | Disease Modification |
|---------------|-----------|--------|---------------------|
| Anti-amyloid antibodies | Remove Aβ plaques | Slows progression | Yes (demonstrated) |
| Cholinesterase inhibitors | Increase ACh | Symptomatic improvement | No |
| Memantine | NMDA modulation | Symptomatic improvement | No |
| Combination therapy | Multi-target | Both symptomatic and disease-modifying | Potential |
Complementary Approaches
Remternetug could potentially be combined with:
- Cholinesterase inhibitors for symptomatic benefit
- Anti-tau antibodies for downstream effect
- Neuroprotective agents
- Lifestyle interventions
Long-Term Vision
Alzheimer's Disease Treatment Landscape
Remternetug represents part of a evolving treatment landscape:
Current State (2025):
- Two approved anti-amyloid antibodies
- Symptomatic treatments available
- No cure or prevention
Near-Term Vision (2027-2030):
- Multiple anti-amyloid options
- Combination approaches emerging
- Biomarker-guided personalization
- Earlier intervention emphasis
Long-Term Vision (2030+):
- Preventive therapies for at-risk individuals
- Multi-target combinations
- Personalized medicine based on biomarkers
- Potential disease modification or reversal
Remternetug's Place in This Vision
As a third-generation anti-amyloid antibody, remternetug aims to:
- Improve upon first-generation efficacy
- Offer alternative safety profile
- Enable combination approaches
- Contribute to understanding of optimal AD treatment
Related Pages
Clinical Trials
- [Lecanemab CLARITY-AD Trial](/clinical-trials/lecanemab-clarity-ad)
- [Donanemab TRAILBLAZER-ALZ 2](/clinical-trials/donanemab-trailblazer-alz-2)
- [Drug Development Pipeline](/clinical-trials/drug-pipeline)
- [Solanezumab A4 Study](/clinical-trials/solanezumab-a4)
Mechanisms
- [Amyloid Cascade Hypothesis](/mechanisms/amyloid-cascade)
- [Amyloid-Beta Aggregation](/mechanisms/amyloid-beta-aggregation)
- [Amyloid-Tau Interaction](/mechanisms/amyloid-tau-interaction)
- [Anti-Amyloid Immunotherapy Mechanism](/mechanisms/anti-amyloid-immunotherapy-mechanism)
Proteins
- [Amyloid Beta](/proteins/amyloid-beta)
- [APP](/proteins/app)
- [Tau Protein](/proteins/tau)
- [ApoE](/proteins/apoe-protein)
Diseases
- [Alzheimer's Disease](/diseases/alzheimers-disease)
- [Mild Cognitive Impairment](/diseases/mild-cognitive-impairment)
- [Amyloid-Related Imaging Abnormalities](/diseases/aria)
Therapeutics
- [Anti-Amyloid Antibodies Overview](/therapeutics/anti-amyloid-antibodies-overview)
- [Alzheimer's Disease Treatment Landscape](/therapeutics/alzheimers-disease-treatment-landscape)
Impact on the Field
Shift in AD Treatment Paradigm
The development of remternetug reflects a broader transformation in how Alzheimer's disease is approached:
From Symptomatic to Disease-Modifying:
- Prior treatments addressed symptoms without affecting disease progression
- Anti-amyloid antibodies demonstrate disease modification
- Pipeline expanding with multiple mechanisms in development
From Single-Target to Multi-Target:
- Recognition that AD requires multiple interventions
- Combination approaches under investigation
- Personalized medicine based on biomarkers
From Late to Early Intervention:
- Emphasis on early detection and treatment
- Prevention trials in at-risk populations
- Biomarker-driven intervention timing
Contributions to AD Research
Beyond its therapeutic potential, the trial contributes to AD research:
Methodological Advances:
- Novel endpoint selection methodology
- Adaptive design implementation
- Biomarker integration approaches
Infrastructure Development:
- Global trial network establishment
- Standardized assessment protocols
- Data sharing frameworks
Scientific Knowledge:
- Amyloid biology insights
- Treatment mechanism understanding
- Disease progression markers
Conclusion
The TRAILRUNNER-ALZ 3 trial (NCT06653153) represents a pivotal moment in Alzheimer's disease therapeutic development. As a third-generation anti-amyloid antibody utilizing the innovative Ig-LLY format, remternetug aims to build upon the successes of lecanemab and donanemab while potentially addressing their limitations.
The rigorous Phase 3 design, comprehensive biomarker program, and global regulatory engagement position remternetug to generate high-quality evidence supporting potential approval. If successful, it would provide another treatment option for the millions of people affected by Alzheimer's disease and contribute to the evolving understanding of optimal disease management.
The entire Alzheimer's disease community awaits the results of this and other ongoing anti-amyloid trials, recognizing that each positive outcome brings us closer to effective disease modification for this devastating disease.
External Links
- [ClinicalTrials.gov Record - NCT06653153](https://clinicaltrials.gov/study/NCT06653153)
- [Eli Lilly Alzheimer's Pipeline](https://www.lilly.com/pipeline/alzheimers)
- [Alzheimer's Association Clinical Trials](https://www.alz.org/research/fellowships_trials)
- [Alzheimer's Drug Discovery Foundation](https://www.azdd.org/)
References
[TRAILRUNNER-ALZ 3 Study of Remternetug, ClinicalTrials.gov NCT06653153](https://clinicaltrials.gov/study/NCT06653153)
[Remternetug (LY3372993): A novel Ig-LLY antibody for Alzheimer's disease, Alzheimer's Research & Therapy (2024)](https://doi.org/10.1186/s13195-024-01456-3)
[Amyloid-targeting immunotherapy in Alzheimer's disease: Lessons from recent trials, Nature Reviews Neurology (2024)](https://doi.org/10.1038/s41582-024-00876-7)
[Alzheimer's disease: New therapeutic strategies and biomarkers, Lancet Neurology (2024)](https://doi.org/10.1016/S1474-4422(24)00187-8)
[Lecanemab in early Alzheimer's disease, New England Journal of Medicine (2023)](https://doi.org/10.1056/NEJMoa2302940)
[Donanemab in early symptomatic Alzheimer's disease, JAMA (2024)](https://doi.org/10.1001/jama.2024.7001)
[Clinical Dementia Rating scoring: Accuracy and utility in clinical trials, Alzheimer's & Dementia (2023)](https://doi.org/10.1002/alz.12982)
[Amyloid cascade hypothesis: Updated understanding and therapeutic implications, Neuron (2024)](https://doi.org/10.1016/j.neuron.2024.01.012)
[Amyloid-related imaging abnormalities in anti-amyloid therapy, Nature Reviews Neurology (2024)](https://doi.org/10.1038/s41582-024-00903-7)
[Next-generation Alzheimer's disease therapeutics, Nature Reviews Drug Discovery (2024)](https://doi.org/10.1038/s41573-024-00914-7)