Interleukin-2 Phase 2 (NCT06096090) — Immunomodulation for Alzheimer's Disease
Executive Summary
Mermaid diagram (expand to render)
This Phase 2 clinical trial investigates the use of low-dose interleukin-2 (IL-2) immunotherapy in patients with mild to moderate [Alzheimer's disease](/diseases/alzheimers-disease). The study, conducted at Houston Methodist Research Institute under the direction of Dr. Alireza Faridar, represents a novel approach to treating [Alzheimer's disease](/diseases/alzheimers-disease) by targeting the immune dysregulation that contributes to [neuroinflammation](/mechanisms/neuroinflammation) and disease progression.
Unlike conventional approaches that target amyloid or tau pathology directly, this trial focuses on modulating the immune system by expanding and restoring functional regulatory T cells (Tregs). This immunomodulation strategy addresses a critical but underappreciated component of [Alzheimer's disease pathophysiology](/mechanisms/neuroinflammation).
Trial Overview
| Parameter | Value |
|-----------|-------|
| NCT Number | NCT06096090 |
| Status | Recruiting |
| Phase | Phase 2 |
| Condition | Alzheimer's Disease |
| Intervention | Interleukin-2 (Aldesleukin) |
| Sponsor | The Methodist Hospital Research Institute |
| Lead Investigator | Alireza Faridar, MD, PhD (Assistant Professor) |
| Location | Houston Methodist Research Institute, Houston, Texas |
| Start Date | January 1, 2022 |
| Primary Completion | December 30, 2025 |
| Study Completion | December 30, 2025 |
| Estimated Enrollment | 40 patients |
| Study Duration | 6-month treatment period + follow-up |
Scientific Rationale
Immune Dysregulation in Alzheimer's Disease
[Alzheimer's disease](/diseases/alzheimers-disease) is increasingly recognized as a disease with significant immune system dysfunction. Research over the past two decades has revealed that the immune system plays a dual role in Alzheimer's disease:
Protective functions: Microglial cells clear amyloid, respond to pathogens, and maintain brain homeostasis
Pathogenic contributions: Chronic inflammation, impaired immune regulation, and autoimmune-like responses drive neurodegenerationKey Immune Abnormalities in AD
| Immune Abnormality | Evidence | Impact |
|-------------------|----------|--------|
| Reduced Treg function | Decreased Treg numbers and suppressive capacity in AD patients[@larbi2009] | Loss of immune regulation, increased inflammation |
| Elevated pro-inflammatory cytokines | Increased IL-1β, TNF-α, IL-6 in AD brains and CSF[@swardfager2018] | Neurotoxicity, synaptic dysfunction |
| Microglial dysregulation | Altered microglial morphology and function in AD brains | Impaired amyloid clearance, chronic inflammation |
| CD8+ T cell infiltration | Clonally expanded CD8+ T cells found in AD brains[@gate2020] | Potential autoimmune attack on neurons |
| Immunosenescence | Accelerated aging of immune system in AD[@pehlivan2023] | Reduced immune function, chronic inflammation |
Regulatory T Cells: The Immune "Brakes"
Regulatory T cells (Tregs) are a specialized subset of T cells that maintain immune homeostasis and prevent excessive inflammatory responses. They function as the "brakes" of the immune system, suppressing the activity of effector T cells, microglia, and other immune cells.
Treg Biology
Development: Tregs develop in the thymus (tTregs) or peripheral tissues (pTregs)
Surface markers: CD4+, CD25+, FOXP3+ (key transcription factor)
Mechanisms of suppression:
- Cell-contact dependent inhibition
- Cytokine secretion (IL-10, TGF-β, IL-35)
- Metabolic disruption of effector cells
- IL-2 consumption (competitive IL-2 deprivation)
Tregs in Alzheimer's Disease
In [Alzheimer's disease](/diseases/alzheimers-disease), Tregs are compromised:
- Reduced numbers: AD patients show decreased circulating Tregs compared to age-matched controls
- Impaired function: Tregs from AD patients have reduced suppressive capacity
- FOXP3 dysregulation: Altered FOXP3 expression and methylation patterns
- Pro-inflammatory shift: Some Tregs convert to pro-inflammatory Th17 cells
This loss of immune regulation contributes to the
chronic neuroinflammation that drives [disease progression](/mechanisms/neuroinflammation).
IL-2: The Treg Growth Factor
Interleukin-2 (IL-2) is a critical cytokine for Treg survival, proliferation, and function. Discovered in 1976, IL-2 was originally characterized as a T cell growth factor but is now understood to have complex, context-dependent effects on the immune system.
IL-2 Signaling
Receptor binding: IL-2 binds to the IL-2 receptor (CD25/CD122/CD132 trimeric complex)
Signal transduction: JAK-STAT, PI3K-AKT, and MAPK pathways
Cellular outcomes:
- T effector cells: Proliferation, activation
- Tregs: Survival, expansion, enhanced suppressive function
- NK cells: Enhanced cytotoxicity
The Low-Dose IL-2 Paradox
A fascinating phenomenon in immunology is that low-dose IL-2 preferentially expands Tregs relative to effector T cells. This occurs because:
- Tregs constitutively express high levels of CD25 (IL-2 receptor alpha chain)
- This gives Tregs a competitive advantage for IL-2 binding at low concentrations
- Effector T cells require higher IL-2 concentrations for activation
- The result: selective Treg expansion with minimal effector cell activation
This selective effect makes
low-dose IL-2 an attractive therapeutic strategy for diseases where Treg deficiency plays a role, including [Alzheimer's disease](/diseases/alzheimers-disease).
Study Design
Trial Type
This is a randomized, double-blind, placebo-controlled trial - the gold standard for clinical research.
Randomization
- Ratio: 1:1 (active:placebo)
- Stratification: By disease severity (MMSE score)
- Block size: Variable (4-6)
Treatment Arms
| Arm | Treatment | Dose | Schedule |
|-----|-----------|------|----------|
| Active | IL-2 (Aldesleukin) | Low dose | Every 2 weeks OR Every 4 weeks |
| Placebo | Matching saline | N/A | Every 2 weeks OR Every 4 weeks |
The study investigates two different dosing schedules to optimize the Treg expansion effect:
- Every 2 weeks: More frequent but lower total exposure
- Every 4 weeks: Less frequent with potential for higher individual doses
Dosing Rationale
The specific dose range is based on:
- Previous studies in other autoimmune conditions showing Treg selectivity
- Phase 1 safety data in elderly populations
- Target blood levels for optimal Treg expansion
- Balance between efficacy and safety
Eligibility Criteria
Inclusion Requirements
| Criterion | Requirement |
|-----------|-------------|
| Age | 50-86 years |
| Diagnosis | Probable Alzheimer's disease per NIA-AA criteria |
| Cognitive status | MMSE 12-26 (mild to moderate impairment) |
| Biomarker | Positive amyloid PET or CSF biomarkers |
| Laboratory | Normal bilirubin, liver enzymes, albumin, creatinine, blood counts, INR |
| Medications | Stable doses of AD medications for ≥4 weeks |
| Capacity | Able to provide informed consent (patient or surrogate) |
Exclusion Criteria
| Exclusion | Reason |
|-----------|--------|
| Active infections | IL-2 can exacerbate immune responses |
| Severe cardiac dysfunction | IL-2 can cause fluid retention, hypotension |
| Hypersensitivity to IL-2 | Safety concern |
| Other primary degenerative dementias | Mixed pathology confounders |
| Active major depression, schizophrenia, bipolar | Psychiatric comorbidity |
| Recent cancer history (≤5 years) | Immunosuppression concerns |
| Contraindications to lumbar puncture | CSF sampling required |
| Immunosuppressive therapy | Interaction with IL-2 effect |
| Prior IL-2 therapy | Prior exposure confounders |
| Active autoimmune disease | Autoimmune confounds |
Key Assessments
Screening Evaluations
- Medical and neurological history
- Physical examination
- Cognitive testing (MMSE, CDR, ADAS-Cog)
- Laboratory tests (CBC, CMP, coagulation)
- Amyloid PET or CSF biomarkers
- MRI brain (within 6 months)
- ECG
- Lumbar puncture (for biomarker collection)
Treatment Period Evaluations
- Vital signs and physical exams at each visit
- Laboratory monitoring at regular intervals
- Cognitive testing at baseline, 3 months, 6 months
- CSF sampling at baseline and 6 months
- Adverse event monitoring
Endpoints
Primary Outcomes
Safety and Tolerability (6 months)
Safety assessments include:
- Adverse events (AEs) - incidence, severity, relationship
- Serious adverse events (SAEs) - monitoring for significant complications
- Laboratory abnormalities - hematology, chemistry
- Vital sign changes - blood pressure, heart rate, temperature
- ECG changes - cardiac safety monitoring
The primary safety concern with IL-2 is
capillary leak syndrome (vascular leak syndrome), characterized by:
- Hypotension
- Edema
- Weight gain
- Reduced organ perfusion
Low-dose IL-2 minimizes this risk while maintaining Treg expansion.
Treg Percentage Change
Key immunologic endpoint:
- Measurement: Percentage of Tregs (CD4+CD25+FOXP3+) out of total CD4+ T cells
- Timepoints: Baseline, 2 weeks, 6 weeks, 3 months, 6 months
- Hypothesis: Low-dose IL-2 will increase Treg percentage by ≥50% from baseline
Secondary Outcomes
| Endpoint | Measurement | Timepoints |
|----------|-------------|------------|
| Cognitive function | MMSE, ADAS-Cog13, CDR | Baseline, 3 months, 6 months |
| Functional status | ADCS-ADL | Baseline, 3 months, 6 months |
| Neuropsychiatric symptoms | NPI | Baseline, 3 months, 6 months |
| Brain volumetry | MRI | Baseline, 6 months |
| CSF biomarkers | Aβ42/40, t-tau, p-tau181 | Baseline, 6 months |
| Inflammatory markers | Cytokines in plasma/CSF | Baseline, 6 months |
| Quality of life | QoL-AD | Baseline, 6 months |
Exploratory Endpoints
- Treg functional assays (suppression capacity)
- Microbiome analysis (gut-immune-brain axis)
- Genetic predictors of response (IL2RA polymorphisms)
- Machine learning models for response prediction
Immunologic Monitoring
Treg Assessment Flow
Baseline → Week 2 → Week 6 → Month 3 → Month 6
↓ ↓ ↓ ↓ ↓
Blood draws for flow cytometry analysis
↓
↓
Measure: CD4+CD25+FOXP3+ percentage and absolute count
Treg suppressive function
Serum IL-2 and soluble IL-2R
Biomarker Rationale
| Biomarker | Rationale |
|-----------|-----------|
| Treg percentage | Direct measure of drug effect on target |
| Treg function | Assesses whether expanded Tregs are functional |
| Inflammatory cytokines | IL-6, TNF-α, IL-1β - tracks neuroinflammation |
| Amyloid/tau biomarkers | Disease progression markers |
| Brain volume | Structural change measure |
Mechanism of Action
How Low-Dose IL-2 May Benefit Alzheimer's Disease
Treg Expansion
- IL-2 stimulates proliferation of existing Tregs
- Increases CD25 expression (positive feedback)
- Promotes Treg survival and longevity
Immune Balance Restoration
- Tregs suppress effector T cells and microglia
- Reduces pro-inflammatory cytokine production
- Shifts microglial phenotype from M1 (pro-inflammatory) to M2 (protective)
Neuroinflammation Reduction
- Decreased IL-1β, TNF-α, IL-6 in the brain
- Reduced microglial activation
- Decreased T cell infiltration into CNS
Potential Disease Modification
- By reducing chronic inflammation, may slow neurodegenerative processes
- May preserve synaptic function and neuronal survival
- May improve cognitive outcomes
Preclinical Evidence
Animal Models
- 5xFAD mice: Low-dose IL-2 reduced microglial activation and improved cognition
- APP/PS1 mice: IL-2 treatment decreased amyloid plaques via Treg-mediated mechanisms
- Aging mice: IL-2 restored Treg numbers and improved hippocampal function
Human Studies
- Autoimmune conditions: Low-dose IL-2 safely expands Tregs in SLE, RA, type 1 diabetes
- Cancer patients: High-dose IL-2 used for melanoma and renal cell carcinoma (different safety profile)
- Healthy elderly: IL-2 improves Treg function and immune parameters
Clinical Significance
Addressing an Unmet Need
Current [Alzheimer's disease](/diseases/alzheimers-disease) treatments:
- Amyloid-targeting antibodies (lecanemab, donanemab): Important but only modestly effective
- Symptomatic medications (donepezil, memantine): Limited benefit
- Immunomodulatory approaches: Underdeveloped
This trial represents a
different mechanism - targeting immune dysregulation rather than amyloid or tau directly.
Advantages of the Approach
Disease mechanism targeting: Addresses neuroinflammation, a core pathological feature
Combination potential: Could be combined with anti-amyloid therapies
Well-characterized safety: IL-2 has been used for decades in other conditions
Orphan mechanism: Targets the Treg deficiency in AD
Biomarker-driven: Can measure target engagement directlyChallenges and Limitations
CNS penetration: IL-2 is a large molecule; CNS effects may be indirect
Treg specificity: Some effector T cell activation may occur
Dosing optimization: Optimal dose and schedule not established for AD
Biomarker validation: CSF vs. blood Tregs correlation unclear
Long-term effects: 6-month treatment may be insufficientComparison with Other Immunotherapy Approaches
| Approach | Target | Mechanism | Status |
|----------|--------|-----------|--------|
| Lecanemab | Amyloid plaques | Antibody-mediated clearance | Approved |
| Donanemab | Amyloid plaques | Antibody-mediated clearance | Approved |
| Aducanumab | Amyloid plaques | Antibody-mediated clearance | Withdrawn |
| Tilavonemab | Tau aggregates | Antibody-mediated clearance | Phase 2 |
| Semorinemab | Tau | Antibody-mediated | Phase 2 |
| AL-002 | TREM2 | Microglial activation | Phase 1 |
| Low-dose IL-2 (this trial) | Immune dysregulation | Treg expansion | Phase 2 |
This trial is unique in targeting immune regulation rather than protein aggregation.
Regulatory Considerations
Current Status
- IND: Active
- Orphan drug: Not specifically for AD (immunomodulators have precedent)
- Fast track: Not granted (not a high-priority pathway)
Future Directions
If successful, this trial could:
Establish proof-of-concept for Treg-targeted therapy in AD
Identify biomarkers predicting response
Guide combination trials with anti-amyloid agents
Support expanded Phase 3 developmentPatient Perspective
Burden of Alzheimer's Disease
[Alzheimer's disease](/diseases/alzheimers-disease) affects over 6 million Americans:
- Cognitive decline: Memory loss, disorientation, language difficulties
- Functional impairment: Loss of independence, need for caregiving
- Behavioral changes: Depression, agitation, sleep disturbances
- Family impact: Caregiver burden, financial costs, emotional distress
Current Treatment Limitations
- Symptomatic therapies: Provide modest, temporary benefit
- Disease-modifying therapies: Limited efficacy, significant risks (ARIA)
- Immunotherapy gap: No immunomodulatory approaches available
Potential Benefits of This Approach
If low-dose IL-2 is effective:
- Reduced neuroinflammation
- Slowed cognitive decline
- Maintained independence longer
- Improved quality of life
- Potential for combination with other therapies
Risks
- Flu-like symptoms (common with IL-2)
- Capillary leak syndrome (rare at low dose)
- Injection site reactions
- Potential for infection (immunosuppression)
- Unknown long-term effects
Future Directions
Next-Generation Immunomodulation
This trial represents the beginning of immune-targeted approaches:
Combination trials: IL-2 + anti-amyloid antibodies
Novel IL-2 formulations: PEGylated IL-2 for improved PK
Alternative targets: TREM2 agonists, CD22 inhibitors
Cell therapy: Ex vivo expanded Tregs
Microbiome modulation: Gut-immune-brain axis approachesBiomarker Development
The trial incorporates extensive biomarker collection to:
- Validate target engagement (Tregs in blood/CSF)
- Identify predictors of response
- Enable patient selection for Phase 3
- Support regulatory approval
Related Pages
Disease and Mechanism Pages
- [Alzheimer's Disease](/diseases/alzheimers-disease) — Overview of AD pathology and treatments
- [Neuroinflammation](/mechanisms/neuroinflammation) — Mechanism of neuroinflammation in neurodegeneration
- [Tau Protein](/proteins/tau) — Target of other immunotherapies
- [Amyloid Beta](/proteins/amyloid-beta) — Amyloid hypothesis and therapies
Therapeutic Approaches
- [Immunotherapy Approaches for AD](/therapeutics/immunotherapy-alzheimers) — Overview of immunotherapy strategies
- [Anti-Amyloid Immunotherapy](/mechanisms/anti-amyloid-immunotherapy) — Monoclonal antibody approaches
- [Lecanemab (NCT01767311)](https://clinicaltrials.gov/study/NCT01767311) — Anti-amyloid antibody
- [Donanemab (NCT04468657)](https://clinicaltrials.gov/study/NCT04468657) — Anti-amyloid antibody
- [Tilavonemab (NCT03580956)](https://clinicaltrials.gov/study/NCT03580956) — Anti-tau antibody
References
[Faridar et al., Low-dose interleukin-2 for Alzheimer's disease: rationale and trial design (2022)](https://doi.org/10.14283/jpad.2022.45)
[Yu et al., Regulatory T cells in Alzheimer's disease: friend or foe? (2020)](https://doi.org/10.1186/s12974-020-01942-3)
[Larbi et al., Dramatic decrease in circulating T cells in Alzheimer's disease (2009)](https://doi.org/10.1016/j.mad.2009.09.005)
[Swardfager et al., Meta-analysis of cytokines in Alzheimer's disease (2018)](https://doi.org/10.1016/j.biopsych.2018.06.015)
[Gate et al., Clonally expanded CD8 T cells patrol the cerebrospinal fluid in Alzheimer's disease (2020)](https://doi.org/10.1038/s41586-020-2246-5)
[Pehlivan et al., Immunosenescence and neuroinflammation in Alzheimer's disease (2023)](https://doi.org/10.1016/j.arr.2023.101857)
[NCT06096090 - ClinicalTrials.gov](https://clinicaltrials.gov/study/NCT06096090)
[Houston Methodist Research Institute](https://www.houstonmethodist.org/research/)