305 Extracellular Vesicular mRNA and miRNA Biomarkers in Patients With Glioblastoma

INTRODUCTION: Glioblastoma (GBM) is a highly lethal primary brain cancer that is resistant to conventional immunotherapies. However, currently, there is a lack of reliable biomarkers for clinical practice. Extracellular vesicles (EVs) present in biofluids are a potential biomarker for GBM diagnosis. METHODS: EVs from cell culture medium, healthy donor and GBM patient serum were purified using tangential flow filtration (TFF). Morphology, size, and numbers of EVs were characterized by TEM and qNano, respectively. EVs from healthy donor and GBM patient serum were compared against other cancer EV samples using bulk mRNA and miRNA sequencing analysis. Selected mRNA and miRNA name are not mentioned due to patents being drafted. mRNA and miRNA expression in EVs were quantified by a fluorescent nucleic acid detection method using a biochip platform at a single-EV level. Fluorescence images were recorded using high-resolution total internal reflection fluorescence (TIRF) microscopy. RESULTS: From bulk mRNA and miRNA sequencing and bioinformatics analysis, three miRNA and two mRNA were selected as potential candidate biomarkers for GBM. Subsequently, EVs from the serum of GBM patients (n = 39) were evaluated through our biochip platform. mRNA and miRNA expression of these biomarkers were positive in single EVs, for which we detected colocalization of protein/RNAs or multiple RNAs in subpopulations of EVs. Our platform was benchmarked with a standard PCR method showing 100X more sensitivity. Moreover, levels of expression of the different RNAs were compared to a cohort of serum from healthy donors (n=20), and showing significant differences between the two groups. CONCLUSIONS: Our non-invasive biochip assay outperformed qRT-PCR for EV RNA detection. Selected mRNAs and miRNAs in subpopulations of EVs could be used as potential GBM biomarkers.