Delineation of Two Clinically and Molecularly Distinct Subgroups of Posterior Fossa Ependymoma

Gene expression (mRNA) profiling of human ependymomas Despite the histological similarity of ependymomas from throughout the neuraxis, the disease likely comprises multiple independent entities, each with a distinct molecular pathogenesis. Transcriptional profiling of two large independent cohorts of ependymoma reveals the existence of two demographically, transcriptionally, genetically, and clinically distinct groups of posterior fossa (PF) ependymoma. Group-A patients are younger, have laterally located tumors with a balanced genome, and are much more likely to exhibit recurrence, secondary metastasis, and death as compared to Group-B patients. Identification and optimization of immunohistochemical markers for PF ependymoma subgroups allowed validation of our findings on a third independent group of tumors using a human ependymoma tissue microarray, and provides a tool for prospective prognostication and stratification of PF ependymoma patients. We analyzed 102 primary ependymomas on the Affymetrix Exon 1.0ST platform (Gene Level).