P05.22.B MOLECULAR PROFILING OF GLIOMAS THROUGH LIQUID BIOPSY: INSIGHTS FROM NEXT-GENERATION SEQUENCING

Abstract BACKGROUND Diffuse high grade gliomas are among the most aggressive brain tumors, characterized by high recurrence rates and poor prognosis. Next-Generation Sequencing (NGS) has emerged as a powerful tool for identifying molecular biomarkers, enabling precise diagnosis, prognostic assessment, and targeted therapy selection. This advanced technique, particularly when integrated with liquid biopsy, allows for noninvasive detection of tumor-specific alterations and real-time monitoring of tumor dynamics. Study aims to evaluate the clinical utility of NGS in identifying molecular alterations from plasma-derived cell-free DNA (cfDNA) in patients with diffuse gliomas, with the goal of refining histopathological diagnoses and establishing its feasibility as a noninvasive diagnostic and monitoring tool. MATERIAL AND METHODS NGS was performed on paired cfDNA and corresponding FFPE tumor tissues from 30 cases of HGGs. The targeted panel was designed to encompass 118 genes relevant to central nervous system (CNS) tumors. Library preparation was performed with a QIAGEN custom panel, and sequencing was conducted on the NovaSeq 6000 platform, adhering to standard protocols. The sequencing achieved a coverage depth of 4000x for FFPE DNA and 7000x for cfDNA, with a sensitivity threshold of 5% allele frequency. Variants were annotated using the GRCh37/hg19 reference genome, and concordance between matched FFPE and cfDNA samples was systematically evaluated. RESULTS NGS analysis identified a diverse range of molecular alterations, including single nucleotide variants (SNVs), insertions, deletions, and structural variations. All cfDNA samples revealed at least one detectable somatic mutation, resulting in a 100% concordance with their corresponding FFPE samples. Key diagnostic alterations detected in cfDNA included ATRX, pTERT, TP53, SMO, PDGFRA, ACVR1, MSH3, EGFR and PTEN mutations. CONCLUSION This study emphasizes the promise of liquid biopsy, particularly cfDNA analysis, as an effective non-invasive tool for glioma diagnosis and management. cfDNA demonstrated 100% concordance with FFPE samples for critical mutations such as TP53, SMO, MSH3, and PTEN, confirming its reliability. Liquid biopsy enables early detection, enhances prognostication, and informs therapeutic decisions, offering a real-time, dynamic method for monitoring tumor progression. By facilitating personalized treatment strategies, cfDNA analysis holds the potential to significantly improve clinical outcomes and advance the management of glioma patients.