[Anaplastic glioma. Neuropathology, molecular diagnostics and current study concepts]

According to the current WHO classification anaplastic gliomas comprise pure astrocytomas and oligodendrogliomas and mixed tumors. This review summarizes findings, discusses problems and defines new questions from the phase III trials on anaplastic gliomas. The molecular subgroup analyses of the NOA-04 trial identified three molecular parameters, which predict longer progression-free and overall survival independent from the mode of therapy, radiotherapy or alkylating chemotherapy-. These are 1p/19q codeletion, methylation of the promoter of the O(6)-methylguanyl methyltransferase (MGMT) gene and hot-spot mutations in the isocitrate dehydrogenase 1 (IDH1) gene. The prognostic relevance of these markers is not lower than that of histopathological subclassification but determination is potentially more robust. Therefore, marker profiles should be included into the next WHO brain tumor classification. The current standard of care for first-line treatment in anaplastic gliomas is radiotherapy or chemotherapy. The next steps, e.g. within the international CATNON trial, are to define the role and optimal sequencing of combined modality treatment focusing on radiotherapy and temozolomide. Inclusion in this trial is already based on the WHO grade and the 1p/19q status and not on the histopathological subtype. Furthermore, anaplastic gliomas are an important group of brain tumors for developing future molecular targeted therapies and should therefore be in the main focus of academic and industrial drug development, which aims at improved efficacy and avoiding long-term side-effects.