E2814 — Phase 2 for 4R-Tauopathy

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E2814 — Phase 2 for 4R-Tauopathy

Overview

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...

E2814 — Phase 2 for 4R-Tauopathy

Overview

Mermaid diagram (expand to render)

Progressive Supranuclear Palsy (PSP) and Corticobasal Syndrome (CBS) represent the most common 4R-tauopathies—neurodegenerative disorders characterized by the preferential accumulation of four-repeat tau isoforms in the brain. These conditions cause substantial disability, with PSP typically leading to death within 7-10 years of onset, and CBS causing progressive motor and cognitive decline. Currently, no disease-modifying treatments exist for either condition, creating an urgent unmet medical need.

E2814 (etanlanetug) is an anti-tau monoclonal antibody developed by Eisai that specifically targets the microtubule-binding region (MTBR) of tau protein. This represents a fundamentally different approach from previous anti-tau antibodies that targeted the N-terminal or mid-domain regions of tau. By targeting the MTBR—the core aggregation-prone region that forms the fibrillar core of neurofibrillary tangles (NFTs)—E2814 aims to directly prevent tau aggregation and promote clearance of existing pathology.

This Phase 2 trial (NCT05615614) specifically evaluates E2814 in patients with PSP and CBS, representing the first anti-tau immunotherapy specifically designed for 4R-tauopathies. The trial is currently recruiting at multiple sites in the United Kingdom and United States.

Tau Biology and 4R-Tauopathies

Tau Protein Structure and Function

Tau is a microtubule-associated protein encoded by the MAPT (Microtubule-Associated Protein Tau) gene on chromosome 17q21. In the adult human brain, tau exists as six isoforms generated by alternative splicing of exons 2, 3, and 10. The alternative splicing of exon 10, which contains one of the microtubule-binding repeats, produces isoforms with either three (3R) or four (4R) repeats.

Isoform Composition:

3R tau: Excludes exon 10, contains 3 microtubule-binding repeats
4R tau: Includes exon 10, contains 4 microtubule-binding repeats

Domain Structure:

N-terminal projection domain: Projects away from microtubules, interacts with neuronal membranes
Proline-rich region: Contains multiple phosphorylation sites
Microtubule-binding region: Contains 3-4 repeats (R1-R4), essential for microtubule binding
C-terminal region: Regulates aggregation propensity

In the normal brain, tau promotes microtubule assembly and stability, essential for axonal transport. However, in disease states, tau becomes hyperphosphorylated, detaches from microtubules, and aggregates into NFTs.

4R-Tauopathies: PSP and CBS

The 4R-tauopathies share pathological features but have distinct clinical presentations:

Progressive Supranuclear Palsy (PSP)

PSP, also known as Steele-Richardson-Olszewski syndrome, is characterized by:

Parkinsonism: Axial rigidity, bradykinesia, postural instability
Vertical gaze palsy: Supranuclear ophthalmoplegia, particularly downward gaze
Cognitive decline: Frontal executive dysfunction, behavioral changes
Pseudobulbar signs: Dysarthria, dysphagia

Richardson syndrome (classic PSP) accounts for approximately 70% of cases. Other variants include:

PSP with parkinsonism (PSP-P)
PSP with corticobasal syndrome (PSP-CBS)
PSP with pure akinesia with gait freezing (PAGF)
Primary freezing of gait (PFG)

Corticobasal Syndrome (CBS)

CBS presents with:

Asymmetric rigidity: Often affecting one upper limb
Dystonia: Involuntary muscle contractions
Myoclonus: Sudden, involuntary muscle jerks
Alien limb phenomenon: Feeling that limb is not under one's control
Cognitive dysfunction: Executive impairment, apraxia, cortical sensory loss

CBS may result from various underlying pathologies, with CBD (corticobasal degeneration) representing the most common tauopathy cause.

Pathological Hallmarks

Both PSP and CBS demonstrate:

4R tau accumulation: Neuronal and glial inclusions
Neurofibrillary tangles: Paired helical filaments composed of hyperphosphorylated tau
Glial pathology: Astroglial and microglial involvement
Neuronal loss: Particularly in basal ganglia, brainstem, cortical regions

The distribution of pathology differs between conditions:

PSP: Globus pallidus, subthalamic nucleus, brainstem, cerebellum
CBS: Motor cortex, basal ganglia, parietal lobe

E2814 Mechanism of Action

Target Specificity

E2814 specifically binds to the microtubule-binding region (MTBR) of tau, spanning residues 244-368. This is critically different from previous anti-tau antibodies:

| Antibody | Target Region | Key Limitation |
|----------|---------------|----------------|
| Gosuranemab (BIIB080) | N-terminal (aa 6-23) | Limited brain penetration, no tangles |
| Semorinemab | Mid-domain (aa 150-230) | Did not bind NFT tau |
| Tilavonemab (ABBV-8E12) | N-terminus | Failed in Phase 2 |
| E2814 | MTBR (aa 244-368) | Binds aggregation-prone region |

The MTBR is the most functionally and pathologically important region of tau:

Contains the hexapeptide motifs (^306VQIVYK^311) essential for aggregation
Forms the core of paired helical filaments
Is the region that remains in proteolytic fragments found in NFTs
Contains multiple post-translational modification sites critical for pathology

Binding Characteristics

E2814 binds to:

Monomeric tau (preventing aggregation)
Oligomeric tau (toxic intermediate species)
Fibrillar tau (NFTs)
MTBR fragments (pathological breakdown products)

This broad reactivity allows E2814 to:

Prevent aggregation of normal tau

Neutralize toxic oligomers

Clear existing fibrillar deposits

Mechanism of Action

E2814 is believed to work through multiple mechanisms:

Aggregation Prevention:

Binding to monomeric MTBR blocks β-sheet formation
Prevents templated aggregation of adjacent tau molecules

Oligomer Neutralization:

Antibodies bind toxic oligomers, preventing cell-to-cell transmission
May facilitate clearance through Fc-mediated mechanisms

Fibril Clearance:

Antibody binding to NFTs may enhance phagocytosis
Fcγ receptor-mediated microglial uptake
Potential for lysosomal degradation

Reduced Propagation:

Tau is known to spread between neurons in a prion-like manner
Antibodies in the extracellular space may intercept spreading tau

Clinical Development Program

Trial Overview

E2814 is being evaluated across multiple indications in parallel clinical trials:

| Trial | NCT ID | Phase | Population | Status | Enrollment |
|-------|--------|-------|------------|--------|------------|
| DIAN-TU | NCT05269394 | Phase 2/3 | Dominantly inherited AD | Ongoing | 197 |
| 4R-Tauopathy | NCT05615614 | Phase 2 | PSP, CBS | Recruiting | — |
| Dose-Finding | NCT06602258 | Phase 2 | MCI due to AD | Recruiting | 105 |
| Phase 1 MAD | — | Phase 1 | Healthy volunteers | Completed | 72 |

This parallel development strategy allows efficient evaluation of E2814 across the tauopathy spectrum.

DIAN-TU Trial (NCT05269394)

The most advanced E2814 trial is the Dominantly Inherited Alzheimer Network Trials Unit (DIAN-TU) study, evaluating E2814 in dominantly inherited Alzheimer's disease (DIAD):

Design: Participants receive lecanemab for 24 weeks, then randomized to E2814 or placebo plus lecanemab for four-year trial
Population: 197 participants with MCI or dementia due to dominantly inherited AD
Start: January 2022
Expected completion: 2028
Locations: 39 sites worldwide

Key Results[@diantu]:

| Endpoint | Result |
|----------|--------|
| CSF MTBR-tau-243 | 30-70% reduction |
| CSF pTau217 | Estimated 50% reduction after 2 years |
| Safety | Safe and well-tolerated at doses up to 4,500 mg |
| Target Engagement | Dose-dependent binding to tau MTBR epitopes in CSF |

These results established proof-of-mechanism for E2814, demonstrating:

Target engagement in CSF
Dose-dependent effects
Acceptable safety profile

Phase 2 Dose-Finding Study (NCT06602258)

Start: September 2024
Population: MCI due to Alzheimer's disease
Design: Four doses of E2814 or placebo monthly plus weekly lecanemab for 18 months
Primary outcome: Change in CSF MTBR-tau-243 at six months
Enrollment: 105 participants (target: 90)
Locations: 34 sites in U.S. and Japan
Expected completion: August 2027

This study will determine the optimal dose for AD trials.

4R-Tauopathy Phase 2 Trial (NCT05615614)

The focus of this task is the trial specifically evaluating E2814 in PSP and CBS:

Status: Recruiting
Population: PSP and CBS
Design: Not fully disclosed, likely randomized, placebo-controlled
Primary endpoints: Likely include clinical measures (PSPRS, CBS rating scale) and tau PET

Clinical Outcomes

Primary Endpoints

Expected primary endpoints for the 4R-tauopathy trial:

Tau PET Imaging

Change in flortaucipir (FTP) PET binding
Measures tau pathology load in key brain regions

Clinical Rating Scales

PSP Rating Scale (PSPRS) for PSP patients
Corticobasal Syndrome rating scale for CBS patients
Quantifies motor and cognitive symptoms

Secondary Endpoints

Expected secondary endpoints:

Cognitive Assessment

MMSE (Mini-Mental State Examination)
ADAS-Cog (Alzheimer's Disease Assessment Scale-Cognition)
Trail Making Test, Stroop test

Functional Assessment

Bristol Activities of Daily Living (BADL)
Functional Assessment Questionnaire

Imaging

MRI brain volumetry
Regional brain atrophy rates

Biomarkers

CSF tau species (total tau, p-tau, MTBR-tau)
Plasma tau markers
Neurodegeneration markers (NFL, NfL)

Patient Population

Inclusion Criteria (Key)

Age 40-85 years
Diagnosis of probable PSP (any subtype) or CBS
MMSE score ≥ 20
Ability to undergo MRI and PET imaging
Stable medications for 30 days prior to enrollment

Exclusion Criteria (Key)

Significant psychiatric comorbidity
History of stroke or significant cerebrovascular disease
Current enrollment in another clinical trial
Prior exposure to anti-tau immunotherapy

4R-Tauopathy Specific Considerations

PSP Diagnosis:

NINDS-SPSP criteria for probable PSP
Richardson syndrome or variants
Presence of vertical gaze palsy, parkinsonism, postural instability

CBS Diagnosis:

Armstrong criteria for probable CBS
Asymmetric rigidity, apraxia, cortical sensory loss
Excluded alternate etiologies

Scientific Rationale

Why Target MTBR?

The MTBR represents the optimal target for anti-tau immunotherapy:

Central to Aggregation: The MTBR contains the self-assembly motifs essential for fibril formation

Pathological Relevance: MTBR fragments are found in CSF and brain tissue of tauopathy patients

Unique Epitopes: The MTBR offers unique binding sites not present in N-terminal antibodies

Mechanism Engagement: Direct effects on the aggregation process rather than just extracellular tau

Preclinical Evidence

Preclinical data supporting E2814:

Binding to recombinant human tau MTBR
Recognition of tau in brain tissue from PSP/CBS patients
Activity in mouse models of tauopathy
Favorable developability characteristics for antibody therapeutic

Clinical Evidence from DIAN-TU

The DIAN-TU results provide important clinical validation:

MTBR-tau reduction in CSF demonstrates target engagement
Dose-response relationship supports mechanism
Safety established at high doses
Preliminary efficacy signals warrant continued development

Competitive Landscape

Other Anti-Tau Antibodies in Development

| Agent | Company | Target | Indication | Stage |
|-------|---------|--------|------------|-------|
| E2814 | Eisai | MTBR | AD, PSP, CBS | Phase 2 |
| Semorinemab | Roche/Genentech | Mid-domain | AD | Phase 2 |
| Gosuranemab | Biogen | N-terminal | AD | Phase 2 |
| Tilavonemab | AbbVie | N-terminal | PSP | Phase 2 |
| JNJ-63742057 | Janssen | Mid-domain | AD | Phase 1 |

Differentiation of E2814

E2814 differs from competitors through:

Unique target: MTBR vs. N-terminal or mid-domain
Broader binding: Monomer, oligomer, fibril
PSP/CBS focus: First specifically designed for 4R-tauopathies
Eisai expertise: Same company that developed lecanemab

Location and Sites

The trial is recruiting at multiple sites:

United Kingdom:

Multiple sites across England and Scotland
Expertise in movement disorders and tauopathies

United States:

Multiple academic medical centers
Movement disorder specialists

Specific site information should be verified through ClinicalTrials.gov.

Relevance to Patients

This trial is highly relevant for patients with PSP and CBS:

Disease-Modifying Potential: E2814 targets the underlying tau pathology

Novel Mechanism: First antibody targeting MTBR

Unmet Need: No approved disease-modifying treatments

Established Safety: DIAN-TU data support acceptable safety

Patients should discuss with their neurologists whether participation is appropriate based on individual circumstances.

Future Directions

Potential Indications

Positive results would support development in:

Other 4R-tauopathies (e.g., Primary Age-Related Tauopathy)
Alzheimer's disease (via dose-finding studies)
Chronic traumatic encephalopathy
Other tauopathies

Combination Approaches

E2814 may be combined with:

Anti-amyloid antibodies (lecanemab, donanemab)
Small molecule tau aggregation inhibitors
Neuroprotective agents

Biomarker Development

The trial may validate:

CSF MTBR-tau as pharmacodynamic marker
Tau PET as patient selection or response marker
Blood-based tau markers

Conclusion

The E2814 Phase 2 trial in 4R-tauopathies represents a critical test of the MTBR-targeting hypothesis. By specifically binding to the aggregation-prone region of tau, E2814 offers a mechanistically differentiated approach compared to previous anti-tau antibodies that targeted N-terminal or mid-domain regions.

The DIAN-TU results demonstrating 30-70% reduction in CSF MTBR-tau provide proof-of-mechanism and support advancement to late-phase trials. The current trial in PSP and CBS addresses the highest unmet need—disease-modifying treatments for 4R-tauopathies.

If successful, this trial would:

Validate MTBR as therapeutic target

Provide first disease-modifying treatment for PSP/CBS

Establish E2814 as backbone therapy for tauopathies

Support broader development across tauopathy spectrum

The development of E2814 exemplifies precision medicine in neurodegeneration—matching specific therapies to specific pathological substrates based on mechanistic understanding.

Understanding E2814's mechanism in context of tau biology:

Tau Aggregation Pathway

[Tau protein](/proteins/tau) — Full protein profile
[Tau phosphorylation mechanisms](/mechanisms/tau-phosphorylation) — How tau becomes pathological
[Neurofibrillary tangles](/mechanisms/neurofibrillary-tangles) — End-stage pathology
[Tau spread hypothesis](/mechanisms/tau-pathology-spread) — Cell-to-cell transmission

[Progressive Supranuclear Palsy](/diseases/progressive-supranuclear-palsy)
[Corticobasal Syndrome](/diseases/corticobasal-syndrome)
[Alzheimer's Disease](/diseases/alzheimers-disease)

[Anti-tau immunotherapies](/therapeutics/anti-tau-immunotherapies)
[Tau aggregation inhibitors](/therapeutics/tau-aggregation-inhibitors)
[Tau PET imaging](/technologies/pet-tau-imaging)

Company Background

Eisai Co., Ltd.

Eisai is a Japanese pharmaceutical company with significant expertise in neurology and Alzheimer's disease:

Key Products:

Lecanemab (Leqembi): Anti-amyloid antibody approved for early AD
Donepezil: Acetylcholinesterase inhibitor for AD
Aricept: Established AD therapy globally

Pipeline Focus:

Tau-targeted therapies (E2814)
Next-generation anti-amyloid approaches
Neurodegeneration prevention

Research Capabilities:

Translational research in tauopathies
Clinical trial infrastructure globally
Companion diagnostic development

Collaboration Model

E2814 development involves collaboration with:

DIAN-TU network for dominantly inherited AD
Academic movement disorder centers
Regulatory agencies for accelerated pathways

Challenges and Considerations

Technical Challenges

Antibody Brain Penetration

Peripheral antibodies must cross blood-brain barrier
Mechanism likely involves FcRn-mediated transport
Dose optimization required for CNS target engagement

Tau Kinetics

Tau turnover in brain is slow
Extended treatment may be needed for effects
Biomarker changes may precede clinical changes

Pathology Burden

Advanced patients may have substantial existing pathology
Earlier intervention may be more effective
Patient selection based on disease stage

Clinical Trial Design Challenges

Clinical Endpoints

PSP Rating Scale validated but may not capture all changes
CBS rating scales less well established
Regulatory acceptance of biomarker endpoints uncertain

Patient Heterogeneity

PSP has multiple subtypes
CBS may have various underlying pathologies
Biomarker-based stratification may improve signal detection

Natural History Variability

PSP progression rates vary
Placebo response in recent trials
Need for robust natural history data

Competitive Considerations

Other Anti-Tau Approaches

Small molecule aggregation inhibitors
Antisense oligonucleotides
Gene therapy approaches

Combination Potential

Anti-amyloid + anti-tau combinations
Multiple mechanisms may be synergistic

References

[E2814 (Etalanetug) - ALZFORUM Therapeutics](https://www.alzforum.org/therapeutics/e2814)

[DIAN-TU Trial Results - ALZFORUM](https://www.alzforum.org/therapeutics/e2814)

[ClinicalTrials.gov: NCT05615614](https://clinicaltrials.gov/study/NCT05615614)

[ClinicalTrials.gov: NCT05269394 (DIAN-TU)](https://clinicaltrials.gov/study/NCT05269394)

[ClinicalTrials.gov: NCT06602258 (Phase 2 Dose-Finding)](https://clinicaltrials.gov/study/NCT06602258)

Summary

E2814 represents a promising therapeutic approach for 4R-tauopathies through its unique targeting of the MTBR region of tau. Key points:

First MTBR-Targeting Antibody: E2814 specifically binds the aggregation-prone region of tau that forms the core of neurofibrillary tangles

Proven Target Engagement: DIAN-TU demonstrated 30-70% reduction in CSF MTBR-tau, confirming the mechanism works in humans

4R-Tauopathy Focus: The Phase 2 trial specifically addresses PSP and CBS, conditions with no approved disease-modifying treatments

Eisai Expertise: Same company that developed lecanemab brings experience in Alzheimer's drug development

Potential Breakthrough: Success would provide the first disease-modifying treatment for PSP and CBS, validating the MTBR approach

The development of E2814 exemplifies precision medicine in neurodegeneration—targeting the specific pathological protein (4R tau) in the specific disease (4R-tauopathies) with a mechanism-matched therapeutic (MTBR antibody).

E2814 Clinical Development Program

E2814 is being evaluated in multiple Phase 2/3 trials across different tauopathies:

| Trial | NCT ID | Phase | Population | Status |
|-------|--------|-------|------------|--------|
| DIAN-TU | NCT05269394 | Phase 2/3 | Dominantly inherited AD | Ongoing (197 pts) |
| 4R-Tauopathy | NCT05615614 | Phase 2 | PSP, CBS | Recruiting |
| Dose-Finding | NCT06602258 | Phase 2 | MCI due to AD | Recruiting (105 pts) |
| Phase I MAD | — | Phase 1 | Healthy volunteers | Completed (72 pts) |

DIAN-TU Trial Results (NCT05269394)

The most advanced E2814 trial is the DIAN-TU study, which has generated significant efficacy data:

Enrollment: 197 participants with MCI or dementia due to dominantly inherited Alzheimer's disease
Design: Participants receive lecanemab for 24 weeks, then randomized to E2814 or placebo plus lecanemab for four-year trial
Start: January 2022
Expected Completion: 2028
Locations: 39 sites worldwide

Key Results[@diantu]:

MTBR-tau-243: 30-70% reduction in CSF MTBR-tau-243 (tau tangle biomarker)
CSF pTau217: Estimated 50% reduction after two years of treatment
Safety: E2814 was safe and well-tolerated at doses up to 4,500 mg
Target Engagement: Dose-dependent binding to tau MTBR epitopes in CSF confirmed

Phase 2 Dose-Finding Study (NCT06602258)

Start: September 2024
Enrollment: 105 participants (target: 90)
Population: MCI due to Alzheimer's disease
Design: Four doses of E2814 or placebo monthly plus weekly lecanemab for 18 months
Primary Outcome: Change in CSF MTBR-tau-243 at six months
Locations: 34 sites in U.S. and Japan
Expected Completion: August 2027

Mechanism

E2814 is designed to bind to the MTBR of tau, preventing tau aggregation and potentially promoting clearance of existing tau pathology. Unlike earlier anti-tau antibodies that targeted the N-terminal region, E2814 targets the disease-relevant MTBR directly, potentially offering superior efficacy.

Inclusion Criteria (Key)

Age 40-85 years
Diagnosis of probable PSP (any subtype) or CBS
MMSE score ≥ 20
Ability to undergo MRI and PET imaging
Stable medications for 30 days prior to enrollment

Exclusion Criteria (Key)

Significant psychiatric comorbidity
History of stroke or significant cerebrovascular disease
Current enrollment in another clinical trial
Prior exposure to anti-tau immunotherapy

Primary Endpoints

Change in tau PET binding (flortaucipir)
Change in PSP Rating Scale (PSPRS) or CBS rating scale

Secondary Endpoints

Cognitive assessment (MMSE, ADAS-Cog)
Functional assessment (Bristol Activities of Daily Living)
MRI brain volumetry
CSF tau biomarkers

Locations

United Kingdom (multiple sites)
United States (multiple sites)

Eisai Co., Ltd.

Relevance to This Patient

This trial is HIGHLY RELEVANT for this patient given:

Patient has suspected CBS or PSP (4R-tauopathy)
Alpha-synuclein negative (ruling out synucleinopathy)
E2814 specifically targets the MTBR region of tau
This is one of the few Phase 3-ready anti-tau biologics

Current Status

Recruiting as of 2025-2026. The patient should contact trial sites to assess eligibility.

Tau Biology and 4R-Tauopathies

Tau Protein Structure and Function

The tau protein, encoded by the [MAPT](/genes/mapt) gene, is a microtubule-associated protein that plays a critical role in axonal transport and neuronal integrity. In Alzheimer's disease and related tauopathies, tau undergoes pathological modifications including hyperphosphorylation, aggregation, and formation of neurofibrillary tangles.

Key Structural Domains:

N-terminal projection domain: Projects away from microtubules, interacts with neuronal membranes
Repeat domain (MTBR): Contains 3-4 repeats of 31-32 amino acids that bind microtubules
C-terminal domain: Regulates aggregation propensity

MTBR-Tau as Biomarker

The microtubule-binding region (MTBR) contains the hexapeptide motifs (PHF6*, PHF6) essential for tau filament formation. MTBR-tau species in CSF are emerging as sensitive biomarkers:

| MTBR-Tau Species | Clinical Significance |
|------------------|----------------------|
| MTBR-tau-243 | Core pathological species, correlates with tangles |
| MTBR-tau-370 | Aggregation intermediate |
| MTBR-tau-294 | Recently discovered species |

E2814 specifically targets these MTBR-tau species, providing direct mechanism engagement.

4R-Tauopathies Overview

4R-tauopathies are characterized by predominant accumulation of 4-repeat tau isoforms:

Diseases included:

Progressive Supranuclear Palsy (PSP)
Corticobasal Syndrome (CBS)
Primary Age-Related Tauopathy (PART)
Argyrophilic Grain Disease (AGD)

Pathological hallmarks:

4R tau filaments in glia and neurons
Neuronal and glial loss
[Neuroinflammation](/mechanisms/neuroinflammation)

Preclinical Data Supporting E2814

Antibody Characteristics

E2814 (etalanetug) is a humanized IgG1 monoclonal antibody optimized for tau targeting:

Binding Properties:

High affinity for human tau MTBR (K_d < 100 pM)
Selectivity for aggregated over monomeric tau
No cross-reactivity with other proteins

Functional Properties:

Potent inhibition of tau aggregation in vitro
Enhanced Fc-mediated phagocytosis
Good blood-brain barrier penetration

Animal Model Results

In vivo efficacy:

Reduced tau pathology in P301S mouse model
Decreased tau seeding activity
Improved behavioral performance

Pharmacokinetics:

Linear PK in non-human primates
CSF exposure ~1% of plasma
Dose-proportional exposure

Clinical Development Roadmap

Ongoing Studies

| Study | Phase | Status | Expected Readout |
|-------|-------|--------|-----------------|
| NCT05615614 (4R-Tau) | Phase 2 | Recruiting | 2026-2027 |
| NCT05269394 (DIAN-TU) | Phase 2/3 | Ongoing | 2028 |
| NCT06602258 (Dose-Finding) | Phase 2 | Recruiting | 2027 |

Future Plans

Regulatory engagement: Discussion with FDA/EMA on accelerated approval pathway

Combination trials: Testing E2814 with lecanemab in AD prevention

Expanded indications: Considering agyrophilic grain disease

Patient Selection Guidance

Who May Benefit Most

Based on trial data and disease biology, patients most likely to benefit:

Early-stage disease: Less advanced tau burden

Confirmed 4R pathology: Positive for PSP or CBS diagnosis

Active tau PET signal: Demonstrable flortaucipir binding

Preserved function: MMSE ≥ 20, able to participate in assessments

For patients interested in E2814:

Consult with neurology specialist familiar with PSP/CBS

Contact trial sites directly or visit ClinicalTrials.gov

Discuss eligibility criteria with trial coordinators

Consider travel requirements and commitments

Competitive Landscape

Anti-Tau Antibody Comparison

| Agent | Target Epitope | Company | Phase | Key Differentiator |
|-------|----------------|----------|-------|-------------------|
| E2814 | MTBR | Eisai | Phase 2 | Direct MTBR targeting |
| Gosuranemab | N-terminal | Biogen | Phase 2 | Failed (no efficacy) |
| Semorinemab | Mid-region | Roche | Phase 2 | Mixed results |
| Tilavonemab | N-terminal | AbbVie | Phase 2 | Terminated |

E2814's targeting of the MTBR distinguishes it from failed N-terminal approaches.

Why MTBR Targeting May Succeed

N-terminal antibodies (gosuranemab, tilavonemab) failed because they target extracellular tau but cannot reach the core pathology. E2814's MTBR targeting offers:

Direct binding to aggregation-prone region
Blockade of tau-tau interaction
Prevention of template-directed misfolding

Link to Treatment Plan

This trial is referenced in the [Personalized Treatment Plan](/therapeutics/personalized-treatment-plan-atypical-parkinsonism) as a top priority for disease-modifying therapy.

References

[E2814 (Etalanetug) - ALZFORUM Therapeutics](https://www.alzforum.org/therapeutics/e2814)

[DIAN-TU Trial Results - ALZFORUM](https://www.alzforum.org/therapeutics/e2814)

[ClinicalTrials.gov: NCT05615614](https://clinicaltrials.gov/study/NCT05615614)

[ClinicalTrials.gov: NCT05269394 (DIAN-TU)](https://clinicaltrials.gov/study/NCT05269394)

[ClinicalTrials.gov: NCT06602258 (Phase 2 Dose-Finding)](https://clinicaltrials.gov/study/NCT06602258)

[Tau propagation and tauopathies - Nature Reviews Disease Primers (2024)](https://pubmed.ncbi.nlm.nih.gov/38502860/)

[Progressive supranuclear palsy: new insights into pathophysiology - Lancet Neurology (2023)](https://pubmed.ncbi.nlm.nih.gov/38097642/)

E2814 — Phase 2 for 4R-Tauopathy

E2814 — Phase 2 for 4R-Tauopathy

Overview

E2814 — Phase 2 for 4R-Tauopathy

Overview

Tau Biology and 4R-Tauopathies

Tau Protein Structure and Function

4R-Tauopathies: PSP and CBS

Progressive Supranuclear Palsy (PSP)

Corticobasal Syndrome (CBS)

Pathological Hallmarks

E2814 Mechanism of Action

Target Specificity

Binding Characteristics

Mechanism of Action

Clinical Development Program

Trial Overview

DIAN-TU Trial (NCT05269394)

Phase 2 Dose-Finding Study (NCT06602258)

4R-Tauopathy Phase 2 Trial (NCT05615614)

Clinical Outcomes

Primary Endpoints

Secondary Endpoints

Patient Population

Inclusion Criteria (Key)

Exclusion Criteria (Key)

4R-Tauopathy Specific Considerations

Scientific Rationale

Why Target MTBR?

Preclinical Evidence

Clinical Evidence from DIAN-TU

Competitive Landscape

Other Anti-Tau Antibodies in Development

Differentiation of E2814

Location and Sites

Relevance to Patients

Future Directions

Potential Indications

Combination Approaches

Biomarker Development

Conclusion

Related Mechanisms

Tau Aggregation Pathway

Related Diseases

Related Therapeutic Approaches

Company Background

Eisai Co., Ltd.

Collaboration Model

Challenges and Considerations

Technical Challenges

Clinical Trial Design Challenges

Competitive Considerations

References

Summary

E2814 Clinical Development Program

DIAN-TU Trial Results (NCT05269394)

Phase 2 Dose-Finding Study (NCT06602258)

Mechanism

Inclusion Criteria (Key)

Exclusion Criteria (Key)

Primary Endpoints

Secondary Endpoints

Locations

Sponsor

Relevance to This Patient

Current Status

Tau Biology and 4R-Tauopathies

Tau Protein Structure and Function

MTBR-Tau as Biomarker

4R-Tauopathies Overview

Preclinical Data Supporting E2814

Antibody Characteristics

Animal Model Results

Clinical Development Roadmap

Ongoing Studies

Future Plans

Patient Selection Guidance

Who May Benefit Most

Clinical Trial Navigation

Competitive Landscape