Introduction: Glioblastoma multiforme (GBM) is an aggressive brain tumor, comprising 46% of all malignant primary brain tumors. Despite advancements in surgery, radiation, and chemotherapy, GBM prognosis remains poor, with a median survival of 14–16 months. More effective diagnostic and therapeutic strategies are urgently needed. Previous studies have shown amantadine, a Health Canada-approved drug, is metabolized via Spermidine/spermine acetyl transferase 1 (SAT1). As SAT1 expression is increased in many different cancers, the present studies examined the acetylation of amantadine and related drugs by GBM cells to determine the potential of these agents as biomarker candidates. Methods: The acetylation of spermidine, amantadine, rimantadine and hydroxyl rimantadine were examined using recombinant acetyltransferase enzymes and human GBM cell lines (U251, LN229, MD59K) cultured under normal conditions and following SAT1 induction with N(1),N(11)-diethylnorspermine (DENSpm) (10uM). The formation of acetylated metabolites was determined either indirectly through fluorometric acetyltransferase assay kit or directly by liquid chromatography mass spectroscopy (LCMS) detection methods. The expression of SAT1 and SAT2 in the GBM cells was determined using immunofluorescence and western blot. The permeability of amantadine, rimantadine and their respective acetylated metabolites were also examined a microfluidic culture model of the blood-brain barrier (BBB). Results: The study highlights SAT1-driven acetylation of amantadine and rimantadine, with acetyl rimantadine formation showing as much as 10-times greater accumulation in GB tumor cells and in the SAT1 recombinant enzyme assays compared to amantadine. Permeability of both the drugs and their acetylated metabolites in the microfluidic BBB culture model ranged from 1 x 10-6 to 10-4 cm/s and were consistent with solutes that can readily pass the BBB. While the acetylation of amantadine and rimantadine was selective for SAT1, studies suggest potential for direct acetylation by acetyl CoA that requires further investigation in the context of GBM drug metabolism. Conclusions: Both amantadine and rimantadine may serve as GBM progression biomarkers, with Acetyl rimantadine showing better potential for diagnostic accuracy based on greater acetylated metabolite formation in GBM cells. These findings suggest that rimantadine could be a more effective biomarker candidate for GBM therapy monitoring.