PSP/CBS Therapeutic Target Index

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PSP/CBS Therapeutic Target Index

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PSP/CBS Therapeutic Target Index

<table class="infobox infobox-therapeutic">
<tr>
<th class="infobox-header" colspan="2">PSP/CBS Therapeutic Target Index</th>
</tr>
<tr>
<td class="label">Target</td>
<td>Modality</td>
</tr>
<tr>
<td class="label">MAPT (tau) mRNA</td>
<td>Antisense oligonucleotide (ASO)</td>
</tr>
<tr>
<td class="label">MAPT splicing</td>
<td>Splice-modulating ASO</td>
</tr>
<tr>
<td class="label">MAPT transcription</td>
<td>Gene therapy</td>
</tr>
<tr>
<td class="label">Target</td>
<td>Modality</td>
</tr>
<tr>
<td class="label">Tau oligomerization</td>
<td>Small molecule</td>
</tr>
<tr>
<td class="label">Tau filament assembly</td>
<td>Small molecule</td>
</tr>
<tr>
<td class="label">Target</td>
<td>Modality</td>
</tr>
<tr>
<td class="label">Extracellular tau</td>
<td>Passive antibody (mid-region)</td>
</tr>
<tr>
<td class="label">Extracellular tau</td>
<td>Passive antibody (N-terminal)</td>
</tr>
<tr>
<td class="label">Extracellular tau</td>
<td>Passive antibody</td>
</tr>
<tr>
<td class="label">Phospho-tau (pSer396/404)</td>
<td>Active vaccine</td>
</tr>
<tr>
<td class="label">Target</td>
<td>Modality</td>
</tr>
<tr>
<td class="label">O-GlcNAcylation</td>
<td>O-GlcNAcase (OGA) inhibitor</td>
</tr>
<tr>
<td class="label">Phosphorylation</td>
<td>Kinase inhibitors</td>
</tr>
<tr>
<td class="label">Acetylation</td>
<td>Acetyltransferase inhibitors</td>
</tr>
<tr>
<td class="label">Target</td>
<td>Modality</td>
</tr>
<tr>
<td class="label">Mitochondrial function</td>
<td>Coenzyme Q10</td>
</tr>
<tr>
<td class="label">Mitochondrial biogenesis</td>
<td>PGC-1α activator</td>
</tr>
<tr>
<td class="label">Complex I support</td>
<td>Small molecule</td>
</tr>
<tr>
<td class="label">Target</td>
<td>Modality</td>
</tr>
<tr>
<td class="label">Microglia activation</td>
<td>CSF1R antagonist</td>
</tr>
<tr>
<td class="label">Complement activation</td>
<td>C1q inhibitor</td>
</tr>
<tr>
<td class="label">TREM2 signaling</td>
<td>TREM2 agonist</td>
</tr>
<tr>
<td class="label">Target</td>
<td>Modality</td>
</tr>
<tr>
<td class="label">BDNF signaling</td>
<td>TrkB agonist</td>
</tr>
<tr>
<td class="label">GDNF delivery</td>
<td>Gene therapy</td>
</tr>
<tr>
<td class="label">CNTF signaling</td>
<td>Protein delivery</td>
</tr>
<tr>
<td class="label">Target</td>
<td>Modality</td>
</tr>
<tr>
<td class="label">Synaptic plasticity</td>
<td>PDE inhibitors</td>
</tr>
<tr>
<td class="label">Excitotoxicity</td>
<td>NMDA modulation</td>
</tr>
<tr>
<td class="label">Synuclein interaction</td>
<td>Alpha-synuclein modulation</td>
</tr>
<tr>
<td class="label">Target</td>
<td>Modality</td>
</tr>
<tr>
<td class="label">Dopamine replacement</td>
<td>Levodopa/carbidopa</td>
</tr>
<tr>
<td class="label">Dopamine agonist</td>
<td>Pramipexole, rotigotine</td>
</tr>
<tr>
<td class="label">Target</td>
<td>Modality</td>
</tr>
<tr>
<td class="label">Pseudobulbar affect</td>
<td>Dextromethorphan/quinidine</td>
</tr>
<tr>
<td class="label">Depression</td>
<td>SSRIs</td>
</tr>
<tr>
<td class="label">Sleep disorder</td>
<td>Melatonin, modafinil</td>
</tr>
<tr>
<td class="label">Target</td>
<td>Modality</td>
</tr>
<tr>
<td class="label">L-type calcium channel</td>
<td>Dihydropyridine antagonists</td>
</tr>
<tr>
<td class="label">Ryanodine receptor</td>
<td>Dantrolene</td>
</tr>
<tr>
<td class="label">Mitochondrial calcium</td>
<td>MCU inhibitors</td>
</tr>
<tr>
<td class="label">Target</td>
<td>Modality</td>
</tr>
<tr>
<td class="label">Autophagy induction</td>
<td>mTOR inhibition</td>
</tr>
<tr>
<td class="label">Autophagy induction</td>
<td>TFEB activation</td>
</tr>
<tr>
<td class="label">Proteasome enhancement</td>
<td>USP30 inhibitors</td>
</tr>
<tr>
<td class="label">Target</td>
<td>Modality</td>
</tr>
<tr>
<td class="label">Ketone metabolism</td>
<td>Ketogenic diet</td>
</tr>
<tr>
<td class="label">Glycolysis modulation</td>
<td>HK2 inhibitors</td>
</tr>
<tr>
<td class="label">Astrocyte metabolism</td>
<td>Lactate transporters</td>
</tr>
<tr>
<td class="label">Category</td>
<td>Trial Count</td>
</tr>
<tr>
<td class="label">Tau immunotherapy</td>
<td>8+</td>
</tr>
<tr>
<td class="label">Tau-lowering ASO</td>
<td>3+</td>
</tr>
<tr>
<td class="label">OGA inhibition</td>
<td>2+</td>
</tr>
<tr>
<td class="label">Neuroprotection</td>
<td>5+</td>
</tr>
<tr>
<td class="label">symptomatic/supportive</td>
<td>15+</td>
</tr>
<tr>
<td class="label">Priority Rank</td>
<td>Target Category</td>
</tr>
<tr>
<td class="label">1</td>
<td>Tau production (MAPT)</td>
</tr>
<tr>
<td class="label">2</td>
<td>Tau aggregation</td>
</tr>
<tr>
<td class="label">3</td>
<td>Tau immunotherapy</td>
</tr>
<tr>
<td class="label">4</td>
<td>O-GlcNAcase</td>
</tr>
<tr>
<td class="label">5</td>
<td>Neuroinflammation</td>
</tr>
<tr>
<td class="label">6</td>
<td>Autophagy enhancement</td>
</tr>
<tr>
<td class="label">7</td>
<td>Mitochondrial function</td>
</tr>
<tr>
<td class="label">8</td>
<td>Neurotrophic support</td>
</tr>
</table>

Overview

This index provides a comprehensive mapping of therapeutic targets for 4R-tauopathies, specifically [progressive supranuclear palsy](/diseases/steele-richardson-olszewski-syndrome) (PSP) and [corticobasal syndrome](/diseases/corticobasal-degeneration) (CBS/CBD). The page integrates the therapeutic pipeline, clinical trial status, and mechanism-to-treatment gaps to identify priority areas for research and development.

PSP and CBS represent the two major clinical syndromes within the 4R-tauopathy spectrum, sharing neuropathological features but differing in regional distribution and clinical presentation[@hoglinger2017][@armstrong2013]. This index organizes therapeutic approaches by molecular target and maps them to the disease mechanisms they aim to address.

Target Taxonomy

Category 1: Tau-Directed Therapies

1.1 Tau Production Lowering

Mechanism-to-Treatment Gap: ASO approaches have demonstrated the strongest pharmacodynamic signal in humans with dose-dependent CSF tau reduction[@mummery2023]. However, delivery requires intrathecal administration, limiting practical accessibility. Next-generation oral or systemic delivery systems are needed.

1.2 Tau Aggregation Inhibition

Mechanism-to-Treatment Gap: Aggregation inhibitors address the seed propagation mechanism critical to tau spreading. However, optimal blood-brain barrier penetration and adequate brain concentrations remain challenging. Early intervention may be required for efficacy.

1.3 Tau Immunotherapy

Mechanism-to-Treatment Gap: Anti-tau antibodies have failed in PSP specifically, raising questions about epitope selection, target engagement timing, and whether extracellular neutralization addresses the core intracellular pathology. Next-generation approaches need 4R-tau-specific epitope targeting and better CNS penetration.

1.4 Tau Post-Translational Modification

Mechanism-to-Treatment Gap: OGA inhibitors aim to shift tau toward less pathological conformations by increasing O-GlcNAcylation. Early biomarker data suggest target engagement, but clinical efficacy remains to be demonstrated. The approach is attractive for chronic oral dosing.

Category 2: Neuroprotective and Disease-Modifying Approaches

2.1 Mitochondrial Protection

Mechanism-to-Treatment Gap: Mitochondrial dysfunction is prominent in PSP pathology, but CoQ10 trials failed to show efficacy. This suggests either timing (too late in disease course) or target inadequacy (CoQ10 may not address the primary mitochondrial deficit).

2.2 Neuroinflammation Modulation

Mechanism-to-Treatment Gap: Neuroinflammation is a prominent feature of PSP/CBS, but anti-inflammatory approaches have not been systematically tested in human trials. Timing and which inflammatory pathway to target remain unclear.

2.3 Neurotrophic Factor Support

Mechanism-to-Treatment Gap: Neurotrophic approaches face delivery challenges across the blood-brain barrier and ensuring proper distribution to affected brain regions. Gene therapy approaches are advancing but require surgical delivery.

2.4 Synaptic Protection

Mechanism-to-Treatment Gap: Synaptic loss correlates with cognitive decline, but no synaptic protective therapies have reached clinical testing in PSP/CBS. Biomarkers for synaptic integrity are needed.

Category 3: Symptomatic Treatments

3.1 Dopaminergic Therapy

Mechanism-to-Treatment Gap: Levodopa provides modest and often transient benefit in PSP, less than in Parkinson's disease, reflecting significant non-dopaminergic pathology. No optimized PSP-specific dopaminergic regimens exist.

3.2 Non-Motor Symptom Management

Mechanism-to-Treatment Gap: Non-motor symptoms significantly impact quality of life but are addressed with repurposed medications not optimized for PSP/CBS-specific pathophysiology.

Category 4: Emerging and Investigational Approaches

4.1 Calcium Homeostasis

Mechanism-to-Treatment Gap: Calcium dysregulation is prominent in PSP neurons but no clinical candidates have advanced beyond preclinical testing.

4.2 Protein Clearance Enhancement

Mechanism-to-Treatment Gap: Enhancing tau clearance through autophagy is conceptually attractive but pharmacologic induction faces toxicity concerns and incomplete understanding of which clearance pathway to engage.

4.3 Cellular Energy Metabolism

Mechanism-to-Treatment Gap: Metabolic deficits in PSP neurons are well-documented but metabolic therapies remain at early experimental stages.

Clinical Trial Landscape Summary

Active/Pending Trials by Mechanism

Trial Design Considerations for PSP/CBS

Endpoint sensitivity: PSP-specific scales (PSPRS, PSP-MDS) may be more sensitive than generic scales

Biomarker enrichment: Tau PET, CSF tau species, and NfL for participant selection

Disease stage: Earlier intervention likely more effective but harder to identify

Composite endpoints: Combining motor, cognitive, and functional measures

Mechanism-to-Treatment Gap Analysis

Critical Gaps

4R-tau-specific mechanisms: Most therapeutic approaches do not specifically target 4R tau isoform biology

Propagation blocking: No therapies specifically block cell-to-cell tau transmission

Astrocyte and oligodendrocyte pathology: Therapies targeting glial tau pathology are lacking

Combination approaches: No systematic evaluation of synergistic therapy combinations

Strategic Priorities

Upstream tau lowering (ASO): Strongest mechanistic rationale based on pharmacodynamic data

4R-selective immunotherapy: Antibodies with specificity for 4R tau conformations

Early intervention biomarkers: Identify individuals before symptom onset for prevention trials

Personalized medicine: MAPT genotype and haplotype-informed targeting

Therapeutic Target Summary Matrix

References

[Höglinger GU et al, Clinical diagnosis of PSP: MDS criteria (2017)](https://pubmed.ncbi.nlm.nih.gov/28467028/)

[Armstrong MJ et al, Criteria for CBS diagnosis (2013)](https://pubmed.ncbi.nlm.nih.gov/25092783/)

[Boxer AL et al, Davunetide in PSP (2014)](https://pubmed.ncbi.nlm.nih.gov/23290595/)

[Mummery CJ et al, MAPTRx in Alzheimer disease (2023)](https://pubmed.ncbi.nlm.nih.gov/37258695/)

[Brendel M et al, 18F-PI-2620 PET in PSP (2021)](https://pubmed.ncbi.nlm.nih.gov/34732787/)

[Anthoney J et al, Tilavonemab for PSP (2024)](https://pubmed.ncbi.nlm.nih.gov/38598789/)

[Kurihara T et al, AMX0035 for PSP (2023)](https://pubmed.ncbi.nlm.nih.gov/37633242/)

[Lees AJ et al, Biomarker and therapeutic advances in PSP (2022)](https://pubmed.ncbi.nlm.nih.gov/35688938/)

[Gegg ME et al, CoQ10 in PSP (2023)](https://pubmed.ncbi.nlm.nih.gov/36951164/)

[Borm GF et al, Bepranemab for PSP and CBD (2024)](https://pubmed.ncbi.nlm.nih.gov/38974321/)

PSP/CBS Therapeutic Target Index

PSP/CBS Therapeutic Target Index

PSP/CBS Therapeutic Target Index

Overview

Target Taxonomy

Category 1: Tau-Directed Therapies

1.1 Tau Production Lowering

1.2 Tau Aggregation Inhibition

1.3 Tau Immunotherapy

1.4 Tau Post-Translational Modification

Category 2: Neuroprotective and Disease-Modifying Approaches

2.1 Mitochondrial Protection

2.2 Neuroinflammation Modulation

2.3 Neurotrophic Factor Support

2.4 Synaptic Protection

Category 3: Symptomatic Treatments

3.1 Dopaminergic Therapy

3.2 Non-Motor Symptom Management

Category 4: Emerging and Investigational Approaches

4.1 Calcium Homeostasis

4.2 Protein Clearance Enhancement

4.3 Cellular Energy Metabolism

Clinical Trial Landscape Summary

Active/Pending Trials by Mechanism

Trial Design Considerations for PSP/CBS

Mechanism-to-Treatment Gap Analysis

Critical Gaps

Strategic Priorities

Therapeutic Target Summary Matrix

References

See Also

Related Hypotheses