EXTH-56. INVESTIGATING THE EFFECTS OF INDIRUBINS IN PEDIATRIC DIFFUSE HIGH GRADE GLIOMA MODELS

Abstract Diffuse midline glioma (DMG) is a highly invasive and fatal pediatric brain tumor that arises from glial cells within the pons of the brainstem. Despite focal radiation treatment, DMG continues to have a poor prognosis, with a median survival of less than 10 months. A significant challenge in treating DMG is the blood-brain barrier (BBB), which tightly restricts access to therapeutic agents, preventing drugs from reaching the brain at effective concentrations. Previous studies from the Lawler lab have shown that the indirubin derivative 6-bromoindirubin-3′-acetoxime (BIO-acetoxime/BIA) has anti-invasive properties and can enhance survival in glioblastoma xenograft models. We investigated the effects of BIA on pediatric glioma models using various assays. In an in vitro scratch migration assay, BIA significantly slowed cell migration at a concentration of 1µM in pediatric glioma cells over 72 hours. Additionally, BIA was shown to modulate tumor vasculature and improve drug delivery to tumors by targeting tight junctions in tumor-associated endothelium. BIA treatment increased dextran uptake into 3D BBB models and lowered endothelial cell permeability in vitro by reducing the expression of tight junction proteins, as shown by staining and a decrease in TEER values. Furthermore, BIA’s anti-angiogenic effects were demonstrated through staining, showing significant alterations in angiogenesis-related protein expression. To assess potential synergistic interactions, a drug screen was performed on a panel of pediatric glioma cell lines identifying several FDA-approved drugs that combine well with BIA. Drugs identified in the screen are currently under investigation. Our hypothesis is that BIA could be an effective therapeutic agent for DMG by targeting tumor invasion, angiogenesis, and improving drug potency and delivery through modulation of endothelial cell tight junctions. Future studies will focus on elucidating the underlying mechanisms and developing drug formulations for in vivo studies to assess the translational potential of this approach.