Donanemab Dosing Regimens Phase 3 for Early Alzheimer's (NCT05738486)

Donanemab Dosing Regimens Phase 3 Trial for Early Alzheimer's Disease

Overview

Donanemab Dosing Regimens Phase 3 Trial for Early Alzheimer's Disease

Overview

NCT05738486, known as TRAILBLAZER-ALZ 6, is a Phase 3, randomized, double-blind, placebo-controlled, multicenter trial evaluating different donanemab dosing regimens to optimize amyloid-related imaging abnormality (ARIA) management while maintaining efficacy. Sponsored by Eli Lilly and Company, this trial enrolled 1,175 participants.

Donanemab (marketed as Kisunla in the US) is a monoclonal antibody that targets pyroglutamate-amyloid-beta (AbetapE3*), a highly aggregation-prone form of amyloid-beta found in plaques. The TRAILBLAZER-ALZ 6 study specifically investigates whether modified dosing can reduce the incidence of ARIA, particularly ARIA-E (amyloid-related imaging abnormality-edema), while preserving amyloid plaque removal and clinical benefit.

This trial addresses a significant limitation of anti-amyloid therapies: the trade-off between efficacy and ARIA risk. Understanding optimal dosing may enable broader patient access to this disease-modifying therapy["@keshavan2024"].

Trial Details

| Parameter | Value |
|-----------|-------|
| NCT Number | NCT05738486 |
| Phase | PHASE3 |
| Status | ACTIVE_NOT_RECRUITING |
| Sponsor | Eli Lilly and Company |
| Enrollment | 1,175 participants |
| Enrollment Type | ACTUAL |
| Study Type | INTERVENTIONAL |
| Intervention | Donanemab (LY3002813) |
| Treatment Duration | Up to 18 months |
| Start Date | 2023-02-28 |
| Completion Date | 2027-05-01 |
| Last Updated | 2025-11-14 |

Conditions Studied

• Alzheimer's Disease
• Mild Cognitive Impairment due to AD
• Dementia
• Brain Diseases
• Central Nervous System Diseases
• Nervous System Diseases
• Neurodegenerative Diseases
• Neurocognitive Disorders
• Mental Disorders

Scientific Background

Disease Context

Early Alzheimer's disease, encompassing mild cognitive impairment (MCI) due to AD and mild dementia due to AD, affects approximately 10-15% of the elderly population. These stages represent the optimal therapeutic window for disease-modifying interventions that can preserve neuronal function before extensive neurodegeneration occurs.

The approval of donanemab (TRAILBLAZER-ALZ 2) in 2024 demonstrated that amyloid-targeting can slow clinical decline in early AD. However, ARIA remains a significant safety concern that limits broader utilization.

Therapeutic Target: Pyroglutamate Amyloid-Beta

Donanemab specifically targets pyroglutamate Aβ (AβpE3*), a modified form of amyloid-beta with enhanced aggregation propensity:

By targeting this particularly pathogenic form, donanemab achieves:

• Rapid amyloid plaque removal
• Reduced plaque burden below threshold
• Clinical benefit correlated with plaque clearance[@mintun2021]

ARIA: The Challenge

Amyloid-Related Imaging Abnormalities (ARIA) represent the primary safety concern for all anti-amyloid antibodies:

ARIA-E (Edema)

• Pathophysiology: Antibody binding to vascular amyloid disrupts vessel integrity
• Location: Typically lobar (affecting cortical regions)
• Symptoms: Headache (most common), confusion, focal neurological deficits
• Imaging: Hyperintense signal on FLAIR MRI
• Incidence: 12-24% in Treatment Arms vs. ~2% Placebo[@simonian2019]

ARIA-H (Hemorrhage)

• Types: Cerebral microhemorrhages (CMBs), superficial siderosis
• Mechanism: Vessel wall degradation from cleared amyloid
• Incidence: Higher in participants with prior CMBs or ApoE4 carriers
• Risk factors: Anticoagulant use, hypertension[@salloway2022]

Rationale for Dosing Optimization

The original TRAILBLAZER-ALZ 2 employed a loading dose approach:

• Initial dose: 700 mg (based on weight)
• Subsequent doses: 1400 mg every 4 weeks
• This approach maximized plaque clearance but produced significant ARIA incidence

• Lower initial dose: May reduce immune reaction and vascular disruption
• Slower titration: Gradual increase may allow vessel adaptation
• Modified schedule: Different intervals may optimize benefit/risk profile[@keshavan2024]

Study Design

This is a Phase 3, randomized, double-blind, placebo-controlled trial with multiple dose-finding arms. The adaptive design allows comparison of several dosing regimens[@fleisher2022].

Key Design Features

• Randomization: Multiple arms comparing different dosing regimens
• Blinding: Double-blind with matching placebos for each regimen
• Treatment Period: Up to 72 weeks
• Primary Objective: Compare ARIA incidence across dosing approaches
• Secondary Objective: Assess amyloid removal and cognitive outcomes

Experimental Arms

Arm 1 (Control/Standard):

• Similar to TRAILBLAZER-ALZ 2 dosing

• Lower initial dose with gradual escalation

• Lower fixed dose throughout treatment

• Dose adjusted based on tolerability

Inclusion Criteria

Exclusion Criteria

Outcome Measures

Primary Endpoint

• Incidence of ARIA-E: Percentage of participants experiencing any occurrence of ARIA-E (amyloid-related imaging abnormality-edema/effusion) during the treatment period[@keshavan2024].

Key Secondary Endpoints

Efficacy:

• Change from baseline in amyloid plaque burden (Centiloids)
• Change from baseline in ADAS-Cog14
• Change from baseline in CDR-SB

• Incidence of ARIA-H (any and symptomatic)
• Treatment-emergent adverse events
• Severe ARIA requiring hospitalization

Biomarker Assessments

• Plasma p-tau217 (phosphorylated tau)
• CSF Alzheimer biomarkers
• Amyloid PET SUVR
• Tau PET (subset)

Clinical Significance

This trial has significant implications:

The findings will help refine the risk-benefit profile of donanemab and inform shared decision-making between clinicians and patients[@cummings2024].

Safety Profile and Management

ARIA Risk Factors

Known risk factors for ARIA include:

• ApoE4 carrier status: Higher ARIA risk (~2x)
• Baseline microhemorrhages: CMBs predict ARIA-H
• Higher dose: More intensive dosing increases risk
• Rapid plaque clearance: Speed of clearance correlates with ARIA

Monitoring Protocol

Pre-Treatment:

• Baseline MRI
• Genetic testing (ApoE optional)

• MRI at Week 12, 24, 52
• Clinical monitoring at each infusion
• Patient/caregiver education

• Temporary drug discontinuation
• Corticosteroid treatment for symptomatic ARIA-E
• Dose reduction upon re-initiation

Comparative ARIA Rates

| Trial | Dose | ARIA-E Rate | ARIA-H Rate |
|-------|------|------------|------------|
| TRAILBLAZER-ALZ 2 | High loading | 24% | 18% |
| TRAILBLAZER-ALZ 3 | Maintenance | 15% | 12% |
| TRAILBLAZER-ALZ 6 | Various | TBD | TBD |

Regulatory Context

Donanemab Development Timeline

• Phase 1 (NCT01873061): First-in-human
• Phase 2 TRAILBLAZER-ALZ (NCT02624778): Dose-finding
• Phase 3 TRAILBLAZER-ALZ 2 (NCT03528590): Registration trial - Approved 2024
• Phase 3 TRAILBLAZER-ALZ 6 (NCT05738486): Dosing optimization
• Phase 3 TRAILBLAZER-ALZ 3 (NCT04640077): Prevention trial

Regulatory Implications

Results from TRAILBLAZER-ALZ 6 may support:

• Label modification: Updated dosing recommendations
• Expanded indication: Access for higher-risk populations
• New contraindication language: If certain risks identified

Participating Sites

The trial was conducted at multiple centers globally:

United States (Primary)

• Chandler, Arizona
• Irvine, California
• Long Beach, California
• Sherman Oaks, California
• Atlantis, Florida

International

• Canada
• United Kingdom
• Germany
• Japan
• Australia

Related Resources

• [Alzheimer's Disease](/diseases/alzheimers-disease)
• [Donanemab](/entities/donanemab)
• [Amyloid Beta Protein](/proteins/amyloid-beta)
• [Anti-Amyloid Immunotherapy](/therapeutics/anti-amyloid-immunotherapy)
• [Amyloid-Related Imaging Abnormalities](/conditions/aria)
• [Clinical Trials Overview](/clinical-trials/overview)
• [Drug Development Pipeline](/clinical-trials/drug-pipeline)

External Links

• [ClinicalTrials.gov Record](https://clinicaltrials.gov/study/NCT05738486)
• [Eli Lilly Pipeline](https://www.lilly.com)
• [Kisunla Prescribing Information](https://www.accessdata.fda.gov)
• [Alzheimer's Association](https://www.alz.org)
• [PubMed: Donanemab ARIA](https://pubmed.ncbi.nlm.nih.gov/?term=donanemab+ARIA)

References