Molecular Subgroups of Glioblastoma– an Assessment by Immunohistochemical Markers

Comprehensive molecular characterization of and novel therapeutic approaches to glioblastoma have been explored as a result of advancements in biotechnologies. In this study, we aimed to bring basic research discoveries closer to clinical practice and ultimately incorporate molecular classification into the routine histopathological evaluation of grade IV gliomas. Integrated results of genome-wide sequencing, transcriptomic and epigenomic analyses by The Cancer Genome Atlas Network defined the classic, proneural, neural and mesenchymal subtypes of this tumor. In a retrospective cohort, we analyzed selected subgroup-defining molecular markers in formalin-fixed paraffin-embedded surgical specimens by immunohistochemistry. Quantitative and qualitative scores of marker expression were tested in hierarchical cluster analyses to evaluate segregations of the molecular subgroups, which then were correlated with clinical parameters including patients' age, gender and overall survival. Our study has confirmed the separation of molecular glioblastoma subgroups with clear trends regarding clinical correlations. Future analyses in a larger, prospective cohort using similar methods are expected to facilitate the development of a molecular diagnostic panel that may complement routine histological work up and support prognostication as well as treatment decisions in glioblastoma.