Integrating Molecular Profiling into Glioma Diagnosis: Implications of the WHO-CNS5-2021 Classification of Adult-Type Diffuse Gliomas in Colombian Patients

Omar Echeverría¹Andrés Felipe Patiño-Aldana²Ana María Chinchilla¹Nora Constanza De Jesús Contreras¹Stevan Peralta¹Nicolas Caballero¹Hanna Valentina Tovar²José Manuel Palacio²Veronica Uribe¹Matteo Mineo-Pachon¹Fernando Velandia³William Mauricio Riveros Castillo⁴Nattaly Valero¹Daniel Silgado⁵Alejandro Oyono Ondo-Méndez²DORA JANETH FONSECA-MENDOZA^1*

• ¹School of Medicine and Health Sciences, Center for Research in Genetics and Genomics (CIGGUR), Institute of Translational Medicine (IMT), Universidad del Rosario, Bogotá D.C., Colombia, bogota, Colombia
• ²School of Medicine and Health Sciences, Clinical Research Group, Universidad del Rosario, Bogotá, Colombia, bogota, Colombia
• ³Consultant neuropathologist, bogota, Colombia
• ⁴Neurosurgery Department, Hospital Universitario Mayor Méderi and Samaritana University Hospital, School of Medicine and Health Sciences, Universidad del Rosario, Bogotá, Colombia., Bogota, Colombia
• ⁵Department of Molecular Diagnosis, Genética Molecular de Colombia SAS, Bogotá, Colombia, Bogota, Colombia

Introduction: Gliomas are the most frequent type of primary malignant central nervous system (CNS) tumors, representing a group of heterogeneous neoplasms with variable clinical behavior that require adequate diagnostic accuracy. The identification of molecular biomarkers has recently gained significance for the diagnosis, prognosis, and treatment of CNS tumors; the application of current clinical guidelines is necessary. Our study performed a molecular characterization of gliomas in a cohort of Colombian patients using the recommendations of the 2021 World Health Organization (WHO) CNS 5 classification. Materials and Methods: We analyzed 22 Colombian patients with CNS tumors. Molecular techniques including Sanger sequencing, Multiplex Ligation-dependent Probe Amplification (MLPA) and Methylation-Specific MLPA (MS-MLPA) were used to identify mutations in IDH1, IDH2, TERT, and EGFR, as well as 1p/19q codeletion and MGMT promoter methylation status. Results: Our results demonstrated a 23% discordance rate between histopathologic and molecular classifications, with most of the discrepancies due to an initial histopathologic classification of glioblastomas, which were molecularly reclassified as astrocytomas. In addition, molecular profiling allowed us to identify non-canonical mutations, including IDH1 p.R132S, which has shown an impact on patient prognosis. Discussion: We highlight the importance of incorporating molecular methods to improve diagnostic accuracy and achieve personalized treatments for gliomas, as proposed by the current 2021 WHO CNS 5 tumor classification guidelines. Performing new studies with larger patient cohorts integrating clinical data is necessary to determine the behavior, epidemiology, and therapeutic outcomes of this type of tumor more comprehensively.