This experiment addresses the critical AD knowledge gap: "What is the function of TREM2 variants in AD risk?" (ranked #13 in AD Knowledge Gaps with 30 points). TREM2 R47H increases AD risk 3x, making it a major genetic risk factor.
Related: AD Knowledge Gap #13 | AD Cure Roadmap | Microglial Mechanisms
How do TREM2 variants (particularly R47H) increase AD risk? Can TREM2 activation restore protective microglial function?
TREM2 (Triggering Receptor Expressed on Myeloid Cells 2) is a receptor on microglia that:
The R47H variant reduces ligand binding (lipids, Aβ) by ~40%, impairing these functions.
Approach: Multi-omics characterization of TREM2 function
| Model | N | Analysis |
|---|---|---|
| TREM2 knock-in mice | Variable | RNA-seq, ATAC-seq |
| iPSC microglia (R47H vs WT) | 20 | Single-cell RNA-seq |
| Human postmortem brain | 60 | Spatial transcriptomics |
Phase 1b/2a Trial Design:
| Cohort | N | Treatment |
|---|---|---|
| AD + TREM2 R47H | 30 | AL002 (AbbVie/Alector) |
| AD + TREM2 R47H | 30 | Placebo |
| AD + WT TREM2 | 20 | AL002 |
Primary endpoints:
Key questions:
Methods:
Model: TREM2 R47H knock-in mice
Interventions:
Readouts:
Deliverables:
| System | Use | Strength |
|---|---|---|
| Human iPSC microglia | Primary model | Patient-specific |
| TREM2 R47H knock-in mice | In vivo | Genetic model |
| Postmortem brain tissue | Validation | Human relevance |
| Cerebral organoids with microglia | Development | 3D model |
| Factor | Assessment |
|---|---|
| Technical Feasibility | High — TREM2 antibodies in development |
| Recruitment Feasibility | Moderate — genetic testing required |
| Cost Estimate | $25-35M over 4 years |
| Timeline | 48 months |
| Cross-Disease Value | High — applicable to ALS, PD |
| Component | Cost (USD) |
|---|---|
| Preclinical studies | $8M |
| Clinical trial (Phase 1b/2a) | $15M |
| Biomarker development | $4M |
| Data analysis | $3M |
| Regulatory | $5M |
| Risk | Mitigation |
|---|---|
| Insufficient brain penetration | Select antibodies with good CNS exposure |
| Off-target effects | Careful safety monitoring |
| Genetic heterogeneity | Stratify by TREM2 genotype |