P.100 Plasma extracellular vesicle sampling from high grade gliomas demonstrates a small RNA signature indicative of disease and identifies lncRNA RPPH1 as a novel biomarker

Abstract

Background: High grade gliomas (HGGs) and cells of the tumour microenvironment secrete extracellular vesicles (EVs) into the plasma that contain genetic and protein cargo which function in paracrine signalling. Isolation of these EVs and their cargo could lead to an important tool that can inform on diagnosis and disease-course of HGGs. Methods: EVs were isolated using Vn96 capture from plasma obtained longitudinally from HGG patients. sRNA was enriched from the EVs, followed by next-generation sequencing, multidimensional scaling, differential expression, and in silico functional enrichment analyses. Results: Over 750 differentially expressed sRNA were identified between HGG and controls. Pathway analysis revealed miRNA highly enriched in both EV and HGG pathways demonstrating the validity of results in capturing a signal from HGG. Other sRNA included several novel HGG plasma-EV biomarkers including lncRNA RPPH1, RNY4, and RNY5. Furthermore, in paired longitudinal patient sampling, RPPH1 informed on surgical resection (decreased on resection) and importantly increased again with clinically defined progression. TCGA analysis demonstrated increased expression of RPPH1 in HGG tissue and additionally, higher expression of RPPH1 was associated with a worse disease-specific prognosis. Conclusions: The present study supports the role of plasma-EV sRNA sampling (and particularly RPPH1) as part of a multi-pronged approach to HGG disease course surveillance.