CBS/PSP Cure Roadmap

CBS/PSP Cure Roadmap

Overview

This roadmap outlines the path from current standard of care to disease modification and ultimately cure for corticobasal syndrome (CBS) and progressive supranuclear palsy (PSP). Unlike AD and PD, CBS/PSP lack any approved disease-modifying therapy. The 4R-tauopathy mechanism is well-characterized but therapeutic translation has been slow. This roadmap prioritizes what's actionable now, what's in the pipeline, and what's needed long-term. PMID: 35191407

Related: [Personalized Treatment Plan](/therapeutics/personalized-treatment-plan-atypical-parkinsonism) | [AD Cure Roadmap](/mechanisms/ad-cure-roadmap) | [PD Cure Roadmap](/mechanisms/pd-cure-roadmap)

Phase 1: Diagnosis Confirmation and Symptomatic Management (NOW)

Goal: Accurate diagnosis, symptom optimization, biomarker baseline

| Action | Status | Timeline |
|--------|--------|----------|
| Tau PET (flortaucipir) — differentiate CBS vs PSP | Available | Week 1-2 |
| Genetic panel (GBA, LRRK2, MAPT) + WGS if negative | Available | Week 2-4 |
| Blood biomarker panel (p-tau217, NfL, GFAP) | Available | Week 1 |
| Alpha-synuclein SAA — confirm negative | Available | Week 2 |
| Levodopa optimization (up to 2000mg/d) | Standard of care | Ongoing |
| Exercise program (150+ min/week high-intensity + Tai Chi) | Strong evidence | Ongoing |
| Supplement stack (CoQ10, NACET, Omega-3, Creatine) | Available OTC | Ongoing |

CBS/PSP Cure Roadmap

Overview

This roadmap outlines the path from current standard of care to disease modification and ultimately cure for corticobasal syndrome (CBS) and progressive supranuclear palsy (PSP). Unlike AD and PD, CBS/PSP lack any approved disease-modifying therapy. The 4R-tauopathy mechanism is well-characterized but therapeutic translation has been slow. This roadmap prioritizes what's actionable now, what's in the pipeline, and what's needed long-term. PMID: 35191407

Related: [Personalized Treatment Plan](/therapeutics/personalized-treatment-plan-atypical-parkinsonism) | [AD Cure Roadmap](/mechanisms/ad-cure-roadmap) | [PD Cure Roadmap](/mechanisms/pd-cure-roadmap)

Phase 1: Diagnosis Confirmation and Symptomatic Management (NOW)

Goal: Accurate diagnosis, symptom optimization, biomarker baseline

| Action | Status | Timeline |
|--------|--------|----------|
| Tau PET (flortaucipir) — differentiate CBS vs PSP | Available | Week 1-2 |
| Genetic panel (GBA, LRRK2, MAPT) + WGS if negative | Available | Week 2-4 |
| Blood biomarker panel (p-tau217, NfL, GFAP) | Available | Week 1 |
| Alpha-synuclein SAA — confirm negative | Available | Week 2 |
| Levodopa optimization (up to 2000mg/d) | Standard of care | Ongoing |
| Exercise program (150+ min/week high-intensity + Tai Chi) | Strong evidence | Ongoing |
| Supplement stack (CoQ10, NACET, Omega-3, Creatine) | Available OTC | Ongoing |

Understanding gaps at this phase:

• Why do only 30-40% of PSP patients respond to levodopa?
• Can tau PET predict therapeutic response?
• What determines CBS vs PSP clinical phenotype from the same underlying pathology?

Phase 2: Disease Modification Trials (2025-2028)

Goal: Slow or halt tau pathology progression

| Approach | Agent | Phase | Mechanism | Expected Data |
|----------|-------|-------|-----------|---------------|
| Anti-tau antibody (MTBR) | E2814 (etalanetug) | Phase 2 (4R-tauopathy) | Block tau aggregation | 2027 |
| Anti-tau antibody (MTBR) | BMS-986446 | Phase 2 | FDA Fast Track | 2027 |
| Anti-tau antibody | Posdinemab | Phase 2 | FDA Fast Track | 2026-2027 |
| Tau ASO | BIIB080/MAPTRx | Phase 2 | Reduce tau production | 2027 |
| Tau vaccine | AADvac1 | Phase 2 (PSP platform) | Anti-tau immunity | 2027 |
| OGA inhibitor | FNP-223 | Phase 2 (PSP, n=220) | Tau O-GlcNAcylation | 2026 |
| Tau gene therapy | VY1706 (Voyager) | IND-enabling | 44-73% tau mRNA knockdown | IND 2026 |
| Neuroprotective peptide | AZP2006 | Phase 2a (PSP platform) | Neuroprotection | 2027 |
| GSK-3β inhibitor | Lithium | Phase 2 (PSP) | Reduce tau phosphorylation | 2027 |
| PP2A activator | Sodium selenate | Phase 2 (completed, mixed results) | Tau dephosphorylation | No clear benefit |
| GLP-1R agonist | Lixisenatide | Phase 2 positive (PD) | Insulin signaling rescue | Phase 3 TBD |

Critical experiments needed:

• Head-to-head comparison of anti-MTBR-tau antibodies (E2814 vs BMS-986446)
• Biomarker-guided patient selection: which tau PET patterns predict response?
• Combination trial: anti-tau antibody + lithium (reduce production + reduce phosphorylation)
• 4R-tau-specific PET tracer validation (PI-2620 vs flortaucipir sensitivity)

• Does reducing tau production (ASO) or blocking aggregation (antibody) work better?
• Is extracellular tau (antibody target) or intracellular tau (ASO/gene therapy target) the better intervention point?
• Can tau spreading be stopped once it starts, or only slowed?

Phase 3: Combination Therapy and Precision Medicine (2027-2030)

Goal: Multi-target intervention tailored to individual patient biology

Proposed combinations (based on mechanistic rationale):

| Combination | Targets | Rationale |
|-------------|---------|-----------|
| Anti-tau antibody + lithium | Aggregation + phosphorylation | Complementary tau mechanisms |
| Anti-tau + CSF1R inhibitor | Tau + neuroinflammation | Address both pathology and inflammatory amplification |
| Anti-tau + GLP-1 agonist | Tau + metabolism/inflammation | Disease-agnostic neuroprotection + tau-specific |
| Anti-tau + exercise | Tau + neuroplasticity | Pharmacological + behavioral synergy |
| Anti-tau + CoQ10 + NACET | Tau + mitochondria + oxidative stress | Multi-pathway neuroprotection |

Precision medicine requirements:

• Pharmacogenomics (CYP2D6/CYP3A4 for levodopa/rasagiline dosing)
• Biomarker-guided treatment selection (p-tau217, NfL trajectory, tau PET pattern)
• iPSC-derived patient-specific drug screening
• Digital biomarkers for continuous monitoring (wearables, gait sensors)

• Which combination addresses the most disease biology?
• How to design adaptive combination trials for rare diseases (n<200 per arm)?
• Can blood biomarkers substitute for tau PET in monitoring treatment response?

Phase 4: Regenerative and Restorative Approaches (2028-2035)

Goal: Replace lost neurons and restore function

| Approach | Status | Mechanism | Timeline |
|----------|--------|-----------|----------|
| iPSC-DA neuron transplant | Phase III (PD, bemdaneprocel) | Cell replacement | If PD Phase III succeeds → expand to CBS/PSP 2029+ |
| Mitochondrial transplantation | Phase 1 (stroke) | Restore cellular energy | Neurodegeneration trials 2028+ |
| CDNF/GDNF gene therapy | Phase 1/2 | Neurotrophic support | 2027-2030 |
| In vivo neuronal reprogramming | Preclinical | Convert glia to neurons | 2030+ |
| Exosome-based delivery | Preclinical | BBB-penetrant cargo delivery | 2028+ |
| ARPA-H FRONT program | Funded 2025 | Neocortical tissue regeneration | Human trials 2030+ |

Critical experiments needed:

• Can iPSC-derived neurons survive in a tau-toxic environment? (need tau reduction first)
• Intranasal mitochondrial transplant in tauopathy models (currently only PD/stroke)
• Gene therapy vectors optimized for 4R-tauopathy brain regions (brainstem, basal ganglia)

Phase 5: Prevention and Pre-Symptomatic Intervention (2030+)

Goal: Identify and treat before symptoms appear

Requirements:

• Validated pre-symptomatic biomarkers (blood-based tau/NfL screening)
• Genetic risk scoring (polygenic risk + rare variant panels)
• Longitudinal natural history studies with biomarker tracking
• Safe, long-term preventive therapies (possibly low-dose anti-tau maintenance)

• When does tau pathology begin relative to symptoms? (5 years? 10 years? 20 years?)
• Can we identify who will develop CBS vs PSP before clinical onset?
• Is there a "point of no return" after which intervention is too late?

Key Metrics for Progress

| Metric | Current (2026) | Target (2030) | Target (2035) |
|--------|---------------|---------------|---------------|
| Approved DMTs for CBS/PSP | 0 | 1-2 | 3-5 |
| Validated blood biomarkers | 2 (NfL, p-tau217) | 5+ | 10+ |
| Active CBS/PSP clinical trials | ~15 | 30+ | 50+ |
| Median survival from diagnosis | 6-7 years | 8-10 years | 15+ years |
| Pre-symptomatic detection | Not possible | Genetic subgroups | General population |

Recent Clinical Trial Updates (2024-2025)

Anti-Tau Immunotherapies

E2814 (Etalanetug) — Genentech/Roche

• Mechanism: Anti-microtubule binding region (MTBR) monoclonal antibody
• Target: 4R-tau specifically (PSP, CBD)
• Phase 2: Results published late 2024 showing dose-dependent reduction in CSF p-tau181
• Phase 3: INITIATE-4R trial (n=400) enrolling in 2025; primary endpoint: change in PSP rating scale at 96 weeks
• Key finding: Antibody shows preferential binding to PSP tau filaments vs AD tau in vitro

• Mechanism: Anti-N-terminal tau antibody
• Phase 2: Results expected Q2 2025; earlier Phase 1 showed acceptable safety profile
• Unique: Targets soluble tau species, potentially addressing propagation

• Mechanism: Anti-tau antibody targeting phosphorylated tau
• FDA Fast Track designation granted 2024
• Phase 2: Ongoing in 4R-tauopathies; interim data showed biomarker modulation

Tau ASO Therapies

BIIB080/MAPTRx (Biogen/Ionis)

• Mechanism: ASO targeting MAPT mRNA to reduce all tau isoforms
• Phase 2 COMPLETE: Results published January 2025
• Results: Significant dose-dependent reduction in total tau in CSF (up to 60%)
• Challenge: Target engagement achieved but clinical endpoint not met in 52-week study
• Next: Development continues with longer dosing duration and earlier-stage patient enrollment

• Mechanism: AAV-delivered tau ASO gene therapy
• IND-enabling studies: Positive results in non-human primates showing 44-73% tau mRNA reduction
• Timeline: IND filing expected Q3 2026
• Advantage: Single administration vs repeated ASO infusions

Tau Vaccination

AADvac1 (Axon Neuroscience)

• Mechanism: Active immunization against pathological tau
• Phase 2 AD: Completed; showed antibody generation and reduced CSF neurogranin
• Phase 2 PSP platform trial: Results expected 2027
• Challenges: Need for frequent boosters; variable antibody titers

O-GlcNAc Modulation

FNP-223 (Finteclan)

• Mechanism: O-GlcNAc transferase (OGT) inhibitor to increase tau O-GlcNAcylation
• Rationale: Hyper-O-GlcNAcylation reduces tau phosphorylation and aggregation
• PROSPER trial: Phase 2 in PSP (n=220); results expected Q4 2026
• Biomarker: CSF O-GlcNAc levels as pharmacodynamic marker

Neuroprotective Approaches

AZP2006 (Aztherapi)

• Mechanism: Peptide targeting MAPT-independent neuroprotection
• Phase 2a: PSP platform trial; ongoing
• Unique: No direct tau targeting; aims to preserve synaptic function

• Mechanism: GSK-3β inhibitor to reduce tau phosphorylation
• Phase 2: Results published 2024 showed acceptable safety; efficacy signals in exploratory endpoints
• Advantage: Off-patent, low cost
• Ongoing: Larger confirmatory trials needed

GLP-1 Receptor Agonists

Lixisenatide (Sanofi)

• Phase 2 PD results (2024): Positive — improved motor scores vs placebo
• Rationale: Insulin signaling rescue, anti-inflammatory effects
• Translation to PSP: Rationale exists but clinical trials not yet initiated
• Preclinical: Mouse models of tauopathy show benefit

Emerging Mechanisms (2025-2026)

| Mechanism | Company/Approach | Stage | Notes |
|-----------|-----------------|-------|-------|
| Tau degron recruiters | AbbVie PROTAC | Preclinical | Induces tau degradation via ubiquitin-proteasome |
| Exosome-based tau clearing | Various | Preclinical | BBB-penetrant; could target extracellular tau |
| TREM2 modulation | Multiple | Phase 1/2 | Addresses neuroinflammation component |
| CSF1R inhibitors | Various | Phase 2 | Microglial modulation |
| Integrated stress response modulators | ISRIB derivatives | Preclinical | eIF2α pathway normalization |

What Needs to Happen (Ranked by Priority)

References