DDDR-24. The Role and Therapeutic Targeting of Diazepam Binding Inhibitor (DBI/ACBP) in Epilepsy and Glioma

Abstract Epilepsy significantly impacts quality of life and markedly affects glioma patients. One-third of patients have drug-refractory epilepsy (DRE), indicating a marked unmet need for new therapeutics. Ex vivo analysis of matched perifocal and electrocorticography positive epileptogenic focal tissue from DRE patients (n=11) revealed an enrichment of a unique microglia polarization state that secretes diazepam binding inhibitor (DBI) (log2 FC = 2.45) in the seizing foci. Ex vivo culture of human microglia from the epileptogenic foci confirmed higher DBI secretion relative to the perifocal tissue (85.7 vs 55.7 ng/ml; p<0.0001). DBI increases the firing rate of primary neuronal-glial co-cultures by 22%. Single-cell spatial transcriptomics using Visium HD of glioblastoma patients, including infiltrating margins (n=4), combined with scRNA seq data (n=110), demonstrates DBI upregulation in tumor cells and co-expression with NLGN3. DBI gene expression is associated with gliomagenesis, radial glia signatures, neural signaling pathways such as NLGN3, tumor connectivity, and lipid metabolism. CSF DBI concentrations are elevated in glioblastoma patients relative to normal controls and diminish after surgical resection. Using a novel lipid-conjugate which delivers an siRNA targeting moiety throughout the CNS, a first-in-class therapeutic, Ntx-DBI, was created. In the chronic pilocarpine model of epilepsy, intrathecal administration of Ntx-DBI eliminates seizure-induced mortality (0%; n=10) relative to the Ntx-nontargeting control (Ntx-NTC) (30%; n=10; p=0.03) and reduced spontaneous seizures (Ntx-DBI: 33%; n=3 vs Ntx-NTC: 100%; n=5; p=0.03). In pre-clinical glioma models, Ntx-DBI increases median survival in CT-2A (Ntx-DBI: undefined vs Ntx-NTC: 33 days; p=0.011) and LN229 (Ntx-DBI: undefined vs Ntx-NTC: 47 days; p=0.02). Mechanistically, Ntx-DBI inhibits fatty acid oxidation and promotes catastrophic lipid peroxidation, driving GBM cell death. In conclusion, DBI plays a dual role in epileptogenesis and gliomagenesis, and when targeted, blocks seizure activity, and increases survival across glioma models.