BIOM-37. EV-TRACK: EXTRACELLULAR VESICLE PROFILING FOR NON-INVASIVE GLIOBLASTOMA DIAGNOSIS AND MONITORING

Abstract Blood-based liquid biopsies are emerging as promising alternatives to classical tissue biopsies and imaging approaches, with considerable potential to facilitate early detection and monitoring of cancer. Nevertheless, their success in brain cancers, unlike in other cancers, has so far been limited, primarily due to the low abundance of tumour-derived analytes in blood as a result of the blood-brain barrier. Here we investigated the use of blood-derived extracellular vesicles (EV) as biomarkers for patients with glioblastoma, the most frequently diagnosed primary malignant brain tumour in adults. EV were isolated from plasma by ultracentrifugation or size exclusion chromatography and subsequently characterised using nanoparticle tracking analysis, digital droplet PCR and nanoflow cytometry. We confirmed previous findings of patients with glioblastoma having higher total EV count than healthy donors. Additionally, we discovered several EV-associated markers on the protein and transcript level that are overexpressed in patients with glioblastoma compared to healthy controls. By performing proteomics analysis, we showed that the marker-carrying EV contain proteins previously linked to enhancement of various cancers. To overcome the scarcity of the tumour-derived EV (tEV) population in blood and to demonstrate its utility in clinical practice, we developed a high-throughput assay using the highly sensitive single molecular array platform (Simoa®) that allows fast and easy detection of total EV and tEV directly in plasma. Therefore, our results introduce a novel blood-based tEV liquid biopsy platform that has the potential to facilitate the current diagnostic and disease monitoring approaches for glioblastoma.