Li Xing, PhD: No financial relationships to disclose
Introduction/Rationale: VAV1 is a highly specific target for immune-mediated diseases. VAV1 functions as a guanine nucleotide exchange factor (GEF) in T- and B-cell receptor signaling and is essential for immune cell activation, proliferation, and inflammatory responses. Despite its therapeutic potential, VAV1 has historically been difficult to target with small molecules due to its multidomain architecture and dual roles as both a GEF and a scaffolding protein involved in GEF-independent signaling pathways. Here, we describe a novel protein degradation strategy using molecular glue degraders (MGDs) to overcome these challenges.
Methods: Endogenous Vav1 protein levels were detected in Jurkat cells by HiBiT assay. In human and mouse whole blood assays, cells were profiled for VAV1 levels in CD3+ T cells with flow cytometry. Label-free mass spectrometry with data-independent acquisition (DIA) proteomics were used to detect protein abundance levels in human PBMC treated with compounds. In vivo pharmacokinetics and efficacies of the compounds upon oral treatment were evaluated in ICR mice and inflammatory disease models including collagen-induced arthritis (CIA), experimental autoimmune encephalomyelitis (EAE) and naïve CD4+ T cell transfer model of inflammatory bowel disease (IBD).
Results: The compounds demonstrated robust VAV1 degradation in both cellular and whole blood assays. The half-maximal degradation concentration (DC50) ranged from sub-nanomolar to low nanomolar, with Dmax values exceeding 95%. Proteomics analysis of human PBMCs confirmed consistent and selective VAV1 degradation. Oral administration of the compounds in animal models resulted in dose-dependent VAV1 degradation and corresponding improvements in disease scores.
Conclusion: We have discovered potent and selective VAV1 molecular glue degraders with favorable in vivo pharmacokinetic and pharmacodynamic properties. Further investigations are needed to explore their potential in treating a range of inflammatory conditions, including neuroinflammation.
