Drug Development.

Area of Science:

• Neuroscience
• Pharmacology
• Molecular Biology

Background:

• Brain glial cells, particularly astrocytes and microglia, are key drivers of Alzheimer's disease (AD) pathogenesis.
• EPHB3 is identified as a novel target mediating neuroinflammation through astrocyte-microglia interactions.
• Small molecule EPHB3 inhibitors were developed to target these astrocyte-mediated disease mechanisms.

Purpose of the Study:

• To test the therapeutic hypothesis that EPHB3 inhibition can attenuate reactive astrocyte signatures in AD models.
• To evaluate the potential of EPHB3 inhibitors to decrease neuroinflammation and rescue behavioral deficits.
• To assess the efficacy of novel small molecule EPHB3 inhibitors in mouse models of amyloidosis (5xFAD) and tauopathy (PS19).

Main Methods:

• Synthesis and characterization of small molecule EPHB3 inhibitors using in vitro kinase and cellular NanoBRET assays.
• Demonstration of pharmacokinetic/pharmacodynamic (PK/PD) properties and in vivo efficacy of VT-001 in EAE, 5xFAD, and PS19 models.
• Assessment of VT-001's effects on astrocyte and microglial mechanisms using single-cell RNA-seq, proteomics, and immunofluorescence, alongside behavioral monitoring.

Main Results:

• VT-001 significantly rescued behavioral deficits and attenuated neuroinflammation in EAE, 5xFAD, and PS19 models.
• Efficacy was linked to reduced reactive astrocyte signatures, neuroinflammation genes, and Aβ plaque-induced gene sets.
• VT-001 demonstrated good tolerability and central nervous system (CNS) exposure; a next-generation inhibitor, VT-002, was identified.

Conclusions:

• VT-001 is a potent and selective EPHB3 inhibitor with significant in vivo efficacy in neuroinflammation and neurodegeneration models.
• EPHB3 inhibitors, particularly VT-001, offer a promising therapeutic strategy for neurodegenerative diseases.
• Targeting astrocyte-mediated disease mechanisms via EPHB3 inhibition presents a novel therapeutic opportunity.