BIOM-34. MULTIPLEX PHENOTYPING OF EXTRACELLULAR VESICLES FOR ANALYSIS OF POTENTIAL BIOMARKERS IN GLIOBLASTOMA PATIENTS

Abstract INTRODUCTION Extracellular vesicles (EVs) carry biological information from their cell of origin that is useful for non-invasive detection tumor biomarkers and disease monitoring. In glioblastoma (GBM), blood circulating EVs are elevated GBM-associated proteins. However, it still challenging to analyze derived translational purposes. Here, we used imaging flow cytometry (IFCM) as a robust strategy perform phenotyping with GBM related surface markers in human plasma. METHODS were isolated via differential ultracentrifugation plasma (a) 40 patients, pre- post-surgery, (b) 11matched relapses (c) 12 healthy donors (HD). EV sizes concentrations evaluated by NTA. (CD9,CD63 CD81) together glioma-related (integrin beta-1 [ITGB1], tenascin C [TNC], Profilin-1 [PFN1], CD44,GPNMB, SPARC, HLA-II or CD133) analyzed IFCM. percentages objects/mL compared among the groups correlated clinical parameters. RESULTS CD9 was predominant tetraspanin all (15-96%), while CD63 had lowest levels (0-33%) strongestdecrease patients after surgery (fold change [FC]=-5.4, p<0.01). Among markers, ITGB1 TNC displayed most significant differences between groups, especially double positives ITGB1+/CD63+and TNC+/CD63+, which decreased removal (FC=-3.5 -12, respectively; p<0.001). Meanwhile,ITGB1+/CD9+and TNC+/CD9+EVs exhibited highest when HD subjects (FC=8.6 17.4;p<0.001) upon recurrence (FC=3.7 10.9, SUMMARY/CONCLUSION We identified antigens potential utility biomarkers. them, highlight promising markers.