P02.16.A IN VIVO TEMPORAL METABOLIC PATTERNS OF GLIOBLASTOMA MICROENVIRONMENT IN A XENOGRAFT MODEL

Abstract BACKGROUND Glioblastoma is marked by a poor prognosis and profound metabolic reprogramming. Mapping its metabolic dynamics is valuable for identifying therapeutic targets. Cerebral open flow microperfusion (cOFM) enables orthotopic implantation of glioma cells and time-resolved, atraumatic sampling of brain interstitial fluid (ISF) directly from the tumor microenvironment (TME) in vivo. Here, ISF and plasma (PL) metabolomics were performed to characterize local and systemic metabolic alterations during tumor progression in a murine xenograft model. MATERIAL AND METHODS Via cOFM, U-87 MG cells were orthotopically implanted in mice, and ISF was sampled from tumor-bearing (GB) and control animals (CTRL) at days 7, 10, and 15 post-implantation (d07, d10 and d15, respectively). PL was collected at baseline (d0) and matched time points. Metabolomics was performed using HILIC UHPLC-HRMS. Data were analyzed using univariate and multivariate methods and subjected to pathway enrichment analysis (PA). RESULTS The ISF metabolome of CTRL and GB exhibited distinct patterns at all time points, primarily driven by differences in the levels of amino acids and glycolysis intermediates, indicating active modulation of tumor energy metabolism. In GB, ISF at d07 and d10 showed elevated fatty acids and lipids compared to CTRLs, a trend no longer evident at d15. Tumor progression was linked to increased markers of inflammation and oxidative stress, and decreased energy substrates. Only in GB, significant correlations were observed between elapsed time and the increase in the levels of kynurenine, as well as the decrease in polyunsaturated fatty acids and glutamine. In contrast to ISF, PL in the GB group showed early (d07-d10) depletion of lipids and fatty acids. In PL, tumor progression over time was correlated with a significant decrease in the levels of carbohydrates, and an increase in the levels of ketone bodies and markers of muscle catabolism. PA of ISF data revealed that significant pathway alterations in the TME expanded from d10 onward, mainly affecting amino acid, lipid, and signaling processes. By d15, broader disruptions emerged in the TME, with many pathways exhibiting metabolic depletion compared to d07. Compared to ISF, PL metabolome changes were concentrated in core metabolic pathways and processes related to nutrient digestion and absorption. Systemic metabolic alterations peaked at d07. Relative to d0, PL at d15 indicated progressive disruption of energy metabolism and the emergence of additional cancer-associated metabolic traits. CONCLUSION Glioblastoma progression drove dynamic, compartment-specific metabolic reprogramming, with early systemic disruption and gradual but extensive remodeling of TME that was marked by evolving metabolic demands and enhanced inflammation-related signaling, indicating critical windows for therapeutic intervention.