• Benedikt Wiestler, David Capper, Martin Sill, David T W Jones, Volker Hovestadt, Dominik Sturm, Christian Koelsche, Anna Bertoni, Leonille Schweizer, Andrey Korshunov, Elisa K Weiß, Maximilian G Schliesser, Alexander Radbruch, Christel Herold-Mende, Patrick Roth, Andreas Unterberg, Christian Hartmann, Torsten Pietsch, Guido Reifenberger, Peter Lichter, Bernhard Radlwimmer, Michael Platten, Stefan M Pfister, Andreas von Deimling, Michael Weller, and Wolfgang Wick.
• Clinical Cooperation Unit Neurooncology, German Cancer Consortium (DKTK) and German Cancer Research Center (DKFZ), Heidelberg, Germany.
• Acta Neuropathol. 2014 Oct 1; 128 (4): 561-71.

AbstractThe outcome of patients with anaplastic gliomas varies considerably. Whether a molecular classification of anaplastic gliomas based on large-scale genomic or epigenomic analyses is superior to histopathology for reflecting distinct biological groups, predicting outcomes and guiding therapy decisions has yet to be determined. Epigenome-wide DNA methylation analysis, using a platform which also allows the detection of copy-number aberrations, was performed in a cohort of 228 patients with anaplastic gliomas (astrocytomas, oligoastrocytomas, and oligodendrogliomas), including 115 patients of the NOA-04 trial. We further compared these tumors with a group of 55 glioblastomas. Unsupervised clustering of DNA methylation patterns revealed two main groups correlated with IDH status: CpG island methylator phenotype (CIMP) positive (77.5 %) or negative (22.5 %). CIMP(pos) (IDH mutant) tumors showed a further separation based on copy-number status of chromosome arms 1p and 19q. CIMP(neg) (IDH wild type) tumors showed hallmark copy-number alterations of glioblastomas, and clustered together with CIMP(neg) glioblastomas without forming separate groups based on WHO grade. Notably, there was no molecular evidence for a distinct biological entity representing anaplastic oligoastrocytoma. Tumor classification based on CIMP and 1p/19q status was significantly associated with survival, allowing a better prediction of outcome than the current histopathological classification: patients with CIMP(pos) tumors with 1p/19q codeletion (CIMP-codel) had the best prognosis, followed by patients with CIMP(pos) tumors but intact 1p/19q status (CIMP-non-codel). Patients with CIMP(neg) anaplastic gliomas (GBM-like) had the worst prognosis. Collectively, our data suggest that anaplastic gliomas can be grouped by IDH and 1p/19q status into three molecular groups that show clear links to underlying biology and a significant association with clinical outcome in a prospective trial cohort.

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