BIOM-33. INVESTIGATING MIR-21 AS A NON-INVASIVE PROGNOSTIC BIOMARKER IN GLIOMA PATIENTS IN RESOURCE CONSTRAINT SETTINGS

Abstract BACKGROUND Glioma treatment remains challenging due to high recurrence rates and resistance to treatment. Diagnosis and follow-up in resource-constrained regions often leads to significant patient attrition. Serum microRNA (miRNA) expression profiles are shown to be expressed in tumor tissue and peripheral samples, offering a pathway for non-invasive, repetitive liquid biopsies. miR-21 shows promise in many populations; however, there is a dearth of data from our region. METHODOLOGY we collected 89 intraoperative tumor tissue samples, 42 pre- and post-operative serum samples from glioma patients, and included 10 control tissue samples along with 8 normal serum samples and analyzed for miR-21 expression through qPCR. Serum samples were collected before tumor resection and post-surgery (pre- and post-operative). Correlational analysis with molecular markers IDH, Ki-67, ATRX, p53, and survival curves through the Kaplan-Meier method were calculated in high and low miR-21 expression groups, The hazard ratio was quantitatively determined using Cox regression analysis, considering both univariate associations and multivariate correlations with clinical parameters. RESULTS miR-21 expression in tissue increased with higher grades of glioma (p=0.00064), of patients above 50 years (p=0.0027), and shows a positive correlation with tumor volume (r= 0.22, p=0.081). IDH-wildtype (p=2.06e-03) and high Ki-67 (p=2.50e-03) expression in tumors showed significant upregulation of miR-21 compared to IDH-mutant and low Ki-67. Patients with low miR-21 expression had significantly longer overall survival (OS) than patients with high miR-21 expression (p =0.006). Quantitative hazard analysis indicates that patients in the high expression group have a 2.77 times higher risk of mortality (95% CI: upper - 0.19, lower - 0.92), in comparison to patients in the low expression group (p= 0.008). CONCLUSION Our findings validate the future utility of miR-21 as a serum assay to help diagnose and assess treatment response in different grades of glioma, within our population. Keywords: Glioma, Biomarker, Molecular markers, Liquid biopsy