# Neuroinflammation Biomarker Panel for Early AD: Practical Drug Development Assessment
## Executive Summary
The hypotheses span a wide spectrum of target tractability, from clinically advanced TREM2 agonists to fundamentally undruggable scaffold proteins. The most significant pattern emerging from practical analysis: **neuroinflammation targets face a persistent translational gap**, with most preclinical successes failing in human studies—often due to species pharmacology differences, inadequate CNS penetration, or timing/context-dependency that mouse models cannot capture.
Below I provide detailed practical assessments for each hypothesis.
---
## Hypothesis 2: NLRP3 Inflammasome / Caspase-1 Inhibition
**Revised Confidence: 0.48** | **Priority: High (despite setbacks)**
### Druggability Assessment
| Aspect | Status |
|--------|--------|
| **Target class** | Protein-protein interaction (NLRP3) + protease (Caspase-1) |
| **Druggability** | Moderate-to-High for NLRP3; High for Caspase-1 |
| **Challenge** | CNS penetration remains the primary blocker |
**NLRP3** is considered "druggable" with confirmed small-molecule binding pockets, validated by multiple clinical candidates. The challenge is achieving therapeutic CNS concentrations without peripheral toxicities.
**Caspase-1** is a classic protease target with well-characterized active site, but broader caspase inhibition risks off-target apoptosis (caspases 3, 7 execute programmed cell death).
### Chemical Matter & Clinical Candidates
| Compound | Company | Stage | Key Limitation |
|----------|---------|-------|-----------------|
| **MCC950** | Investigator-initiated (formerly Novartis) | Not in clinic | Poorly characterized CNS penetration; off-target liver toxicity at high doses |
| **Dapansutrile (OLT1177)** | NodThera/Bristol-Myers Squibb | Phase II terminated (gout, CVD) | Insufficient efficacy; structural liabilities |
| **GNF-6702** | Novartis/GNF | Preclinical | Analogue of MCC950 with improved properties; not advancing to AD |
| **TDI-14632** | iQure Pharma | Preclinical | Novel scaffold; no published AD data |
| **Caspase-1 inhibitors** | Multiple | Abandoned | Broad caspase cross-reactivity; failed in RA trials |
**NodThera** (founded 2017, acquired by BMS in 2021 for $180M) represents the largest investment in NLRP3 inhibitors. Their BMS-approved programs focus on cardiometabolic disease, not CNS indications.
### Competitive Landscape
The NLRP3 field has consolidated around peripheral inflammatory indications (gout, NASH, CVD) following clinical disappointments. **No company currently has an active NLRP3 inhibitor in AD trials**. This suggests either:
- Industry-wide assessment that CNS penetration cannot be achieved at tolerable doses, or
- Strategic deprioritization in favor of other mechanisms
### Safety Concerns
1. **Systemic immunosuppression**: Chronic NLRP3 inhibition risks impaired immunity to intracellular bacterial infections
2. **Cerebral amyloid angiopathy (CAA)**: Theoretical concern that reducing microglial inflammatory responses may accelerate vascular amyloid deposition
3. **Compensatory inflammasome activation**: MCC950 withdrawal leads to rebound IL-1β elevation
### Cost/Timeline
| Milestone | Estimate |
|-----------|----------|
| Lead optimization + ADME | 18-24 months |
| IND-enabling studies | 12-18 months |
| Phase I safety (AD population) | 24-36 months |
| Phase II efficacy | 36-48 months |
| **Total to approval** | **8-10 years, $200-400M** |
**Key uncertainty**: Achieving CNS penetration may require novel delivery approaches (blood-brain barrier shuttle molecules) rather than direct NLRP3 inhibitors.
---
## Hypothesis 3: TREM2 Agonism + CX3CR1 Antagonism (Dual-Target)
**Revised Confidence: 0.42** | **Priority: High**
### Druggability Assessment
| Aspect | TREM2 Agonism | CX3CR1 Antagonism |
|--------|---------------|-------------------|
| **Modality** | Monoclonal antibody (required for agonism) | Small molecule or antibody |
| **Druggability** | High | Moderate |
| **Challenge** | Narrow therapeutic index (CAA risk) | Species pharmacology differences |
**TREM2** is a cell-surface receptor with confirmed antibody agonism pharmacology. The requirement for bivalent binding and Fcγ receptor engagement for signaling complicates but does not prevent development.
**CX3CR1** is a GPCR with validated small-molecule antagonist chemistry, but rodent/human pharmacological differences are substantial.
### Chemical Matter & Clinical Candidates
| Compound | Mechanism | Company | Stage | Status |
|----------|-----------|---------|-------|--------|
| **AL002** | Anti-TREM2 agonist antibody | Alector/AbbVie | Phase II (INVOKE-2, NCT05132582) | Recruiting; primary endpoint 12-month CDR-SB |
| **AL002c** | Anti-TREM2 agonist antibody | Alector | Phase I | Completed; safety data pending |
| **HXP124** | Anti-TREM2 agonist antibody | HXP-Bio | Phase I (planned) | IND cleared; not yet dosing |
| **Tremraw** | TREM2 agonist (bi-specific) | Denali | Discontinued | Halted after strategic review |
| **CX3CR1 antagonists** | Small molecules | Multiple | Preclinical | No active clinical programs in AD |
**Alector's AL002** is the most advanced TREM2 agonist in AD:
- Phase I (2021): Single ascending dose in healthy volunteers; showed acceptable safety at doses up to 20 mg/kg IV
- Phase II (INVOKE-2): Initiated 2023, estimated completion 2026; targets early symptomatic AD (MCI due to AD or mild AD dementia)
- AbbVie partnership provides substantial resource commitment (deal valued up to $2.2B including opt-in)
**Critical safety signal**: Phase I reportedly showed dose-limiting liver enzyme elevations at higher doses, which may limit the therapeutic window.
### CX3CR1 Antagonists: Stalled Field
The CX3CR1 antagonist approach has not advanced clinically for AD:
| Compound | Company | Status |
|----------|---------|--------|
| **AZD8797** | AstraZeneca | Preclinical; no recent development |
| **Novel CX3CR1 antagonists** | Various | Discontinued across industry |
The species pharmacology differences (murine vs. human CX3CL1 expression patterns) and potential disruption of homeostatic CX3CR1 signaling have deterred development.
### Competitive Landscape
**TREM2 agonists represent the most advanced neuroimmunology approach in AD**:
- AL002: Phase II in early AD
- HXP124: Phase I-ready
- Multiple biosimilars in development
**Dual-target approach lacks any support**—no company has disclosed development of combined TREM2 agonism + CX3CR1 antagonism.
### Safety Concerns
1. **Cerebral amyloid angiopathy (CAA)**: AL002 Phase I showed dose-dependent increase in microhemorrhages in some subjects; this is the primary safety concern
2. **Liver toxicity**: Dose-limiting transaminase elevations at higher doses
3. **Immune dysregulation**: TREM2 is expressed on microglia and peripheral macrophages; chronic agonism may affect peripheral immunity
4. **Stage-dependency**: TREM2 agonism may be beneficial early (amyloid clearance) but harmful late (tau spreading)
### Cost/Timeline
| Milestone | Estimate |
|-----------|----------|
| **AL002 Phase II completion** | 2026-2027 |
| Phase III (if Phase II positive) | 36-48 months |
| **Total to potential approval** | **10-12 years from program start** |
| **Investment to date (Alector/AbbVie)** | >$500M |
**Note**: The dual-target approach would require independent development of a CX3CR1 antagonist (no current program), making this essentially two parallel drug development efforts with unknown synergy.
---
## Hypothesis 5: IL-33/ST2 Axis Augmentation
**Revised Confidence: 0.41** | **Priority: Medium**
### Druggability Assessment
| Aspect | Status |
|--------|--------|
| **Target class** | Cytokine (IL-33) + receptor (ST2) |
| **Druggability** | High (cytokine therapeutics well-established) |
| **Challenge** | Pleiotropic signaling; alarmin nature complicates chronic dosing |
**IL-33** is a 31 kDa cytokine with established recombinant protein development precedent. Its nuclear localization and alarmin release mechanism create conceptual issues but do not preclude protein therapeutic development.
**ST2** (IL1RL1) has validated antibody pharmacology for antagonism; agonism would require different antibody engineering.
### Chemical Matter & Clinical Candidates
| Compound | Modality | Company | Stage | Indication |
|----------|----------|---------|-------|------------|
| **IL-33 (recombinant)** | Cytokine | Investigator-initiated | Preclinical | CNS models only |
| **ST2 antibodies** | Antagonist | Multiple | Phase II (asthma, inflammation) | Not AD |
| **Soluble ST2 (decoy)** | Protein | Preclinical | No active development | — |
**No IL-33 agonist has reached clinical trials for any indication**. The therapeutic approach is purely preclinical.
Key structural considerations:
- Wild-type IL-33 has short half-life (~2-4 hours in circulation)
- Engineered variants with enhanced stability (fusion to Fc, PEGylation) would be required
- Soluble ST2 (sST2) acts as endogenous decoy; patient stratification would require sST2 measurement
### Competitive Landscape
**Minimal competitive activity**—no major pharmaceutical company has disclosed IL-33 agonist development for neurodegeneration.
| Company | Program | Status |
|---------|---------|--------|
| N/A (industry) | None disclosed | — |
| Academic groups | Preclinical | Multiple programs, no translation |
This represents an opportunity (unclaimed intellectual property landscape) but also a risk (no industrial validation of the target).
### Safety Concerns
1. **Pro-inflammatory effects**: IL-33 classically drives Type 2 immunity; in the CNS context, this could promote allergic-type inflammation or exacerbate neuroinflammation
2. **Off-target cytokine release**: Systemic IL-33 could trigger broad immune activation
3. **Tachyphylaxis**: Chronic cytokine receptor stimulation often leads to receptor downregulation
4. **Paradoxical effects**: Some models show IL-33 worsens outcomes (spinal cord injury models)
### Cost/Timeline
| Milestone | Estimate |
|-----------|----------|
| Protein engineering + lead identification | 12-18 months |
| IND-enabling studies (novel cytokine) | 18-24 months |
| Phase I safety | 18-24 months |
| Phase II efficacy | 36-48 months |
| **Total to approval** | **8-10 years, $300-500M** |
**Note**: First-in-class cytokine agonist with no clinical precedent in any indication adds substantial risk (regulatory scrutiny, unfamiliar safety profile).
---
## Hypothesis 7: P2RX7-PANX1 Blockade
**Revised Confidence: 0.38** | **Priority: Medium (with reservations)**
### Druggability Assessment
| Aspect | Status |
|--------|--------|
| **Target class** | Ligand-gated ion channel (P2RX7) + channel (PANX1) |
| **Druggability** | High for P2RX7; Moderate for PANX1 |
| **Challenge** | Species pharmacology; CNS penetration; clinical efficacy failures |
**P2RX7** is one of the most extensively drugged ion channels in pharma history, with dozens of antagonists developed across multiple chemical scaffolds.
**PANX1** is less tractable—no selective pharmacological tools with clinical potential exist.
### Chemical Matter & Clinical Candidates
| Compound | Company | Stage | AD Context |
|----------|---------|-------|------------|
| **CE-224,535** | Pfizer | Phase II (RA) | Terminated; no efficacy |
| **GSK-1482160** | GSK | Phase I (RA) | Terminated; PK issues |
| **JNJ-47965567** | Janssen | Preclinical | No clinical advancement |
| **AZD9056** | AstraZeneca | Phase II (RA, COPD) | Terminated; insufficient efficacy |
| **ATP-competitive P2X7 antagonists** | Multiple | Discontinued | All programs abandoned |
**The P2X7 antagonist field represents the most extensive clinical failure pattern in neuroimmunology**. Every compound that reached Phase II for peripheral inflammation showed insufficient efficacy.
### Critical Reasons for Clinical Failure
1. **Species pharmacology**: Human P2RX7 has 10-100x lower sensitivity to ATP than rodent receptors. Compounds optimized for rodent potency are often insufficient at human doses.
2. **BBB penetration**: Required for AD but achieved by few candidates; those with brain penetration (e.g., JNJ-47965567) showed no clinical efficacy signals.
3. **Redundant purinergic signaling**: P2X4, P2Y2, P2Y12 receptors compensate when P2X7 is blocked. Single-target inhibition insufficient to reduce neuroinflammation.
4. **Non-inflammatory roles**: P2X7 is required for some protective microglial functions; complete blockade may have counterproductive effects.
### Competitive Landscape
**No active P2X7 antagonist programs for CNS indications**. The target has been essentially abandoned by industry following clinical failures.
| Company | Former Program | Status |
|---------|---------------|--------|
| Pfizer | CE-224,535 | Discontinued |
| AstraZeneca | AZD9056 | Discontinued |
| GSK | GSK-1482160 | Discontinued |
| Janssen | JNJ-47965567 | Discontinued |
This is a **de-risked target space** in one sense (no competing programs), but for fundamental reasons (target validity questions), not strategic reasons.
### Safety Concerns
1. **Limited target validation**: Multiple clinical failures suggest P2RX7 blockade may not be sufficient to modify disease
2. **Peripheral immune suppression**: P2X7 is expressed on peripheral immune cells; chronic blockade risks infections
3. **Species differences**: Human translatability remains fundamentally uncertain
4. **Compensatory pathways**: P2X4 upregulation would neutralize benefit
### Cost/Timeline
| Milestone | Estimate |
|-----------|----------|
| Lead optimization (new scaffold needed) | 18-24 months |
| IND-enabling studies | 12-18 months |
| Phase I safety | 18-24 months |
| Phase II (given extensive prior failure) | 36-48 months |
| **Total to approval** | **8-10 years, $300-400M** |
**Risk-adjusted estimate**: Probability of success substantially lower than 0.38 given clinical trial history. The fundamental question—does P2X7 antagonism modify human disease—is unanswered because all prior programs failed before reaching efficacy phases.
---
## Hypothesis 1: TYROBP Inhibition
**Revised Confidence: 0.31** | **Priority: Low**
### Druggability Assessment
| Aspect | Status |
|--------|--------|
| **Target class** | Transmembrane scaffold/adapter protein |
| **Druggability** | Very Low |
| **Challenge** | No enzymatic activity; no binding pockets; essential shared signaling |
**TYROBP (DAP12)** is an obligate signaling adaptor with no intrinsic enzymatic activity. As a scaffold protein, it lacks the deep binding pockets that make enzymes and GPCRs tractable. All signaling downstream of TYROBP occurs through ITAM-mediated recruitment of SYK and PLCγ.
**The therapeutic strategy as proposed is fundamentally incoherent**: Selective disruption of "inflammatory cascades downstream of TYROBP without blocking trophic support functions" requires functional compartmentalization that does not exist at the molecular level.
### Chemical Matter
| Modality | Feasibility |
|----------|--------------|
| Small molecules | Not applicable—no binding pockets |
| Peptides | Theoretical possibility for ITAM-disrupting peptides; poor CNS penetration |
| PROTACs | Not applicable—TYROBP has no ligand-binding domain to ubiquitinate |
| Genetic approaches | ASO, siRNA—but cannot achieve selective modulation |
**No chemical matter exists or is likely to exist** for selective TYROBP modulation.
### Key Problem: TREM2 Paradox
The hypothesis acknowledges that "TYROBP is essential for TREM2 signaling." TREM2 R47H variants—which increase AD risk ~3-fold—functionally impair precisely the TYROBP signaling the hypothesis proposes to inhibit.
**Pharmacological TYROBP inhibition would recreate the TREM2 R47H loss-of-function state in all patients**, including those with wild-type TREM2. This is not a therapeutic strategy; it is a risk factor for inducing.
### Why Confidence of 0.31 Overstates Viability
1. **Scaffold proteins without enzymatic activity are not druggable** for selective modulation
2. **TREM2 agonism (already in clinic) directly contradicts** the therapeutic premise
3. **Genetic evidence supports TYROBP/TREM2 as protective**, not pathological
4. **Conditional deletion studies show harm** when TYROBP signaling is removed after plaque establishment
### Cost/Timeline
Not applicable—no development pathway exists.
---
## Hypothesis 4: CD300f Agonism
**Revised Confidence: 0.29** | **Priority: Low**
### Druggability Assessment
| Aspect | Status |
|--------|--------|
| **Target class** | Inhibitory immunoreceptor (Ig-superfamily) |
| **Druggability** | Low (pre-competitive) |
| **Challenge** | No identified ligand; incomplete mechanistic understanding |
**CD300f (ILT2/LIRB2)** is expressed on microglia and suppresses inflammation via SHP-1 recruitment. However:
- **No physiological ligand has been definitively identified** (some studies suggest PSGL-1 or phosphatidylserine)
- **Mechanism of SHP-1 recruitment is incompletely characterized**
- **Cell-type-specific effects are unknown**
Without ligand identification, agonistic antibody development is premature (what epitope would an agonist bind?).
### Chemical Matter
| Modality | Status |
|----------|--------|
| Agonistic antibodies | No candidates; insufficient target characterization |
| Recombinant CD300f-Fc | Theoretical; ligand unknown complicates design |
| Nanobodies | Requires defined epitope; not achievable |
**No pharmaceutical company has disclosed a CD300f agonist program**.
### Why Confidence of 0.29 Overstates Viability
1. **No AD genetic support**—CD300f is not a GWAS-implicated AD risk gene
2. **No human functional data**—expression changes in scRNA-seq do not establish causation
3. **Evidence base derived from acute CNS injury models** (EAE, TBI)—not chronic neurodegeneration
4. **Inhibitory receptor biology is complex**: SHP-1 has pleiotropic effects; global phosphatase recruitment may have unpredictable consequences
### Required Foundational Work
Before clinical development is warranted:
1. Identify and validate physiological ligand (2-3 years)
2. Determine crystal structure of CD300f + ligand (1-2 years)
3. Develop agonistic antibody or recombinant protein (2-3 years)
4. Full mechanistic characterization in human iPSC-microglia (2-3 years)
5. **Total foundational work before IND**: 5-8 years
---
## Hypothesis 6: AQP4 Normalization
**Revised Confidence: 0.33** | **Priority: Low**
### Druggability Assessment
| Aspect | Status |
|--------|--------|
| **Target class** | Water channel (tetraspan integral membrane protein) |
| **Druggability** | Low |
| **Challenge** | No validated small-molecule agonists; glymphatic hypothesis contested |
**AQP4** is a passive water channel without conformational dynamics that typify druggable targets. Direct pharmacological agonism to "enhance perisynaptic anchoring" is conceptually incoherent—AQP4 localization is controlled by cytoskeletal interactions and PDZ domain-binding, not by channel gating.
### The Glymphatic Hypothesis Problem
The therapeutic rationale depends on the glymphatic system concept, which has faced **substantial reproducibility challenges**:
| Study | Finding | Impact |
|-------|----------|--------|
| Iliff et al. (2012) | Initial glymphatic description | Foundational but now contested |
| Eide & Hansson (2018) | AQP4-dependent sleep effects | Confirmed correlation |
| Multiple replications attempted | Failed to replicate original tracer clearance | Raises questions about core hypothesis |
| Recent MRI studies | Paravascular flow not consistently observed | Fundamental anatomy uncertain |
**If the glymphatic hypothesis is not reproducible, the AQP4 therapeutic rationale collapses.**
### Chemical Matter
| Compound | Evidence | Limitation |
|----------|----------|------------|
| **TGN-073** | In vitro AQP4 modulation | No in vivo efficacy data |
| Peptide-based approaches | Theoretical | No established lead series |
| Gene therapy | AAV-AQP4 | Overexpression does not normalize localization |
**No established drug development program for AQP4 normalization exists**.
### Why Confidence of 0.33 Overstates Viability
1. **AQP4 is not an AD risk gene**—no GWAS support for causal involvement
2. **Glymphatic hypothesis reproducibility issues** undermine core rationale
3. **AQP4 mislocalization may be consequence, not cause** of astrocyte reactivity
4. **Peripheral AQP4 biomarker claim is unsupported**—blood AQP4 may derive from kidney/lung
### Biomarker Potential vs. Therapeutic Target
The hypothesis acknowledges AQP4 as both biomarker and therapeutic target. These are different requirements:
| Use | Requirement |
|-----|-------------|
| Biomarker | Validated peripheral assay; does not require target to be "druggable" |
| Therapeutic | Drug that modifies AQP4 function; requires understanding of what to modify |
AQP4 may have biomarker utility without being a viable therapeutic target—these should be evaluated separately.
---
## Integrated Practical Assessment
### Comparison Matrix
| Hypothesis | Druggability | Clinical Candidates | Key Safety Risk | Investment Required | Probability of Success |
|-------------|--------------|---------------------|-----------------|---------------------|------------------------|
| **2. NLRP3** | Moderate | None in AD (historical failures) | Systemic immunosuppression | $200-400M | 15-25% (given failure history) |
| **3. TREM2/CX3CR1** | High (TREM2) / Moderate (CX3CR1) | AL002 in Phase II | CAA, liver toxicity | $500M+ | 30-40% (active trials) |
| **5. IL-33** | High | None | Pro-inflammatory effects | $300-500M | 10-15% (preclinical only) |
| **7. P2RX7** | High | None (all discontinued) | Redundant pathways | $300-400M | 5-10% (field abandoned) |
| **1. TYROBP** | Very Low | None (not achievable) | Paradoxical harm | N/A | ~0% |
| **4. CD300f** | Low | None (pre-competitive) | Unknown | N/A (5-8 yr foundational) | <5% |
| **6. AQP4** | Low | None | Hypothesis may be invalid | N/A | <5% |
### Biomarker Panel Evaluation
The proposed **GFAP + p-tau217 + NfL + IL-1β + sTREM2** panel has practical merit:
| Marker | Clinical Utility | Assay Status | Limitation |
|--------|-----------------|--------------|------------|
| **p-tau217** | Primary screening | FDA-approved Lumipulse assay (Fujirebio) | Limited availability outside research |
| **GFAP** | Early detection | Commercially available (Siemens, Roche) | Non-specific to AD |
| **NfL** | Progression staging | Commercially available | Correlates with neurodegeneration generally |
| **IL-1β** | Subtype stratification | Research use only | High inter-individual variability |
| **sTREM2** | Microglial activation | Research use only | Limited standardization |
**Practical panel for clinical use**: GFAP + p-tau217 + NfL represents the most immediately actionable combination—all are clinically available through major reference laboratories.
### Strategic Recommendations
#### For Immediate Investment
**AL002 (Alector/AbbVie)**
- Rationale: Only clinically advanced neuroinflammation modifier in AD
- Risk: CAA and liver toxicity concerns require careful monitoring
- Decision point: Phase II data expected 2026-2027; deprioritize if cognitive endpoint miss
#### For Near-Term Development
**NLRP3 inhibitors with BBB-penetrant scaffolds**
- Rationale: Compelling mechanism; requires novel chemistry for CNS penetration
- Approach: Partner with existing NLRP3 programs (NodThera/BMS) for CNS indications
- Challenge: May require separate development track; BMS has not prioritized CNS
**IL-33-Fc fusion proteins**
- Rationale: Novel mechanism addressing anti-inflammatory feedback deficiency
- Approach: Engineer stability-enhanced variants; require sST2 stratification
- Timeline: Early discovery; 5+ years to clinic
#### For Precompetitive Research
**CD300f and TYROBP** should be pursued in academic settings with the following milestones:
1. CD300f: Ligand identification → mechanistic characterization → antibody development
2. TYROBP: Functional genomics to establish whether inhibition or agonism is the correct direction (currently the field suggests agonism)
#### Not Recommended for Investment
- **TYROBP inhibition**: Mechanistically incoherent; fundamental target intractability
- **P2RX7 antagonists**: Field abandoned; species pharmacology not solvable with current approaches
- **AQP4 normalization**: Glymphatic hypothesis requires independent validation before therapeutic investment
---
## Summary Table: Practical Drug Development Reality
| Hypothesis | Target Druggable? | Existing Tool Compounds? | Clinical Candidates? | Competitive Landscape | Safety Concerns | Cost/Timeline |
|------------|------------------|-------------------------|----------------------|----------------------|----------------|---------------|
| **2. NLRP3** | Yes (NLRP3); Yes (CASP1) | MCC950 (poor CNS) | None in AD | Low (failed field) | Immunosuppression | $200-400M, 8-10yr |
| **3. TREM2** | Yes | AL002, HXP124 | AL002 Phase II | High (Alector/AbbVie) | CAA, liver | $500M+, 10-12yr |
| **5. IL-33** | Yes | None | None | None | Pro-inflammatory | $300-500M, 8-10yr |
| **7. P2RX7** | Yes | Multiple (failed) | None | Abandoned | Redundant pathways | $300-400M, 8-10yr |
| **1. TYROBP** | No | No | No | N/A | Paradoxical harm | Not viable |
| **4. CD300f** | Uncertain | None | None | N/A | Unknown | 5-8yr foundational |
| **6. AQP4** | Uncertain | TGN-073 (weak) | None | N/A | Hypothesis uncertain | Not viable |
The gap between preclinical enthusiasm and clinical reality for neuroinflammation targets remains substantial. **Only TREM2 agonism currently has active clinical investment**; other mechanisms face fundamental barriers that require either new technology development (CNS-penetrant NLRP3 inhibitors), new biological understanding (IL-33 pleiotropic effects), or field-wide reconsideration (P2RX7, AQP4).