TMIC-53. USE OF CEREBRAL OPEN-FLOW MICROPERFUSION TO IDENTIFY POTENTIAL ONCOMETABOLITE, L-2-HYDROXYGLUTARATE, IN GLIOBLASTOMA CHEMOTHERAPY ADAPTATION

Abstract Glioblastoma (GBM) is among the most prevalent and lethal brain tumors, comprising nearly half of all central nervous system malignancies and imparting a median overall survival of only 18-20 months. One major challenge in curing this disease is the limited understanding of how GBM cells biologically respond to treatments like radiotherapy and chemotherapy, including temozolomide (TMZ), in real-time. A significant challenge is observing changes within the tumor interstitial fluid (ISF), which mediates adaptive intercellular signaling between tumor cells and their surrounding tumoral and stromal neighbors. Microfluidic sampling methods, such as cerebral microdialysis and microperfusion, have started to provide valuable insights into the ISF signaling dynamics. These methods enable real-time biomolecular monitoring of this often-neglected component of the tumor microenvironment (TME). We have performed in vivo cerebral open-flow microperfusion (cOFM) pilot studies to identify metabolomic and proteomic changes within the tumor ISF resulting from differential treatment with either TMZ or vehicle control. Among these metabolite and protein changes, we identified an increase in 2-hydroxyglutarate (2-HG). While D-2-HG is a hallmark metabolite of isocitrate dehydrogenase mutant (IDH-mut) tumors, our model utilized the IDH wild-type (IDH-WT) CT2A mouse-syngeneic glioma model. Subsequent analysis of enantiomeric confirmation characterized this to be predominantly L-2-HG. Follow-up in vitro studies have shown that elevated L-2-HG plays a functional role in IDH-WT patient-derived glioma cells via non-canonical HIF1α stabilization and subsequent expression of HRE genes. This suggested that L-2-HG may play a similar role in IDH-WT GBM as D-2-HG plays in IDH-mutant tumors. This study demonstrates the potential of L-2-HG to function as a chemo-responsive oncometabolite in the TME of highly aggressive IDH-WT glioblastoma. By targeting the metabolic and signaling properties of L-2-HG, it may be possible to prevent chemo-resistant adaptations mounted by GBM cells when treated with TMZ.