Die WHO-Klassifikation der Tumoren des zentralen Nervensystems 2021

Hintergrund Die von der Weltgesundheitsorganisation (WHO) herausgegebene Klassifikation der Tumoren des zentralen Nervensystems (ZNS) wurde 2016 überarbeitet, um molekulare Biomarker aufzunehmen, die für die Diagnosestellung und klinische Entscheidungsfindung wichtig sind. Danach verfeinerte ein internationales Konsortium die ZNS-Tumor-Klassifikation durch einige Empfehlungen, die aktuell in die neue WHO-Klassifikation 2021 eingeflossen sind. Fragestellung Welche Neuerungen in der WHO-Klassifikation 2021 haben direkte Auswirkungen auf die Diagnostik und Behandlung von erwachsenen Patienten mit diffusen Gliomen? Material und Methoden Die diagnostischen Kriterien der WHO-Klassifikation 2021 für diffuse Gliome wurden bezüglich dieser Fragestellung untersucht. Ergebnisse Mutationen in den Isocitratdehydrogenase(IDH)-Genen 1 oder 2 spielen eine entscheidende Rolle bei der Klassifikation von Gliomen. Unter den IDH-mutierten Gliomen identifiziert der Verlust der nukleären ATRX-Expression IDH-mutierte Astrozytome, während der Nachweis einer 1p/19q-Kodeletion für Oligodendrogliome diagnostisch ist. Die Nomenklatur für das IDH-mutierte Glioblastom wurde in Astrozytom, IDH-mutiert, ZNS-WHO-Grad 4 geändert. Die homozygote Deletion des CDKN2A/B-Genlocus ist ein molekularer Marker für diese Tumoren. Die Bezeichnungen „anaplastisches Astrozytom“ bzw. „anaplastisches Oligodendrogliom“ für IDH-mutierte Gliome des ZNS-WHO-Grads 3 entfallen. Diffuse astrozytäre Gliome ohne IDH-Mutation, die eine Mutation im Promotor des Telomerase-Reverse-Transkriptase(TERT)-Gens, eine Amplifikation des epidermalen Wachstumsfaktorrezeptorgens (EGFR), einen kombinierten Gewinn von Chromosom 7 und Verlust von Chromosom 10 (+7/−10) oder mehrere dieser Veränderungen aufweisen, werden jetzt als Glioblastom, IDH-Wildtyp, ZNS-WHO-Grad 4 klassifiziert, auch wenn histologisch weder pathologische Gefäßproliferate noch Nekrosen nachweisbar sind. Zudem wurden neue Gliome vom pädiatrischen Typ eingeführt, die vornehmlich bei Kindern, Jugendlichen und jungen Erwachsenen auftreten und von den o. g. häufigen Gliomen vom adulten Typ differenziert werden. Diskussion Die WHO-Klassifikation 2021 hat neben neuen Tumortypen auch grundlegende Veränderungen auf dem Boden neuer molekularpathologischer Erkenntnisse berücksichtigt, welche die diagnostische Präzision erhöhen und die klinische Versorgung durch modifizierte Behandlungsempfehlungen verbessern. Die neue Klassifikation hat zudem große Auswirkungen auf das Design zukünftiger klinischer Studien in der Neuroonkologie. = Background The World Health Organization (WHO) classification of tumors of the central nervous system (CNS) was revised in 2016 to incorporate molecular biomarkers of importance for tumor diagnostics and clinical decision making. Thereafter, the cIMPACT-NOW consortium published a series of recommendations for the future classification of CNS tumors that have subsequently been incorporated into the new WHO classification 2021. Objectives Which changes in the WHO classification 2021 directly affect the diagnosis and treatment of adult patients with diffuse gliomas? Materials and methods The criteria of the WHO classification 2021 for diffuse gliomas were examined with regard to this question. Results Mutations in the isocitrate dehydrogenase (IDH) genes 1 or 2 remain important for the classification of diffuse gliomas. Among IDH-mutant gliomas, loss of nuclear ATRX expression identifies IDH-mutant astrocytomas, while 1p/19q codeletion is diagnostic for IDH-mutant and 1p/19q-codeleted oligodendrogliomas. The nomenclature for IDH-mutant glioblastoma was changed to astrocytoma, IDH-mutant, CNS WHO grade 4. Homozygous deletion of the CDKN2A/B gene locus is a novel molecular biomarker for these tumors. IDH-wildtype diffuse astrocytomas carrying a telomerase reverse transcriptase (TERT) promoter mutation, epidermal growth factor (EGFR) gene amplification, and/or combined gains of chromosome 7 and losses of chromosome 10 (+7/−10) are now classified as IDH-wildtype glioblastomas, even when histology shows no microvascular proliferation and/or necrosis. In addition, several new pediatric-type diffuse gliomas have been introduced that must be distinguished from the more common adult-type diffuse gliomas. Conclusions The 2021 WHO classification 2021 introduces new tumor types and implements fundamental conceptual changes based on new molecular findings, which increase diagnostic precision and improve clinical care through modified treatment recommendations. The new WHO classification also has a major impact on the design of future clinical trials in neuro-oncology

EGFR cooperates with EGFRvIII to recruit macrophages in glioblastoma

: Amplification of the EGFR gene and its truncation mutant EGFRvIII are hallmarks of glioblastoma. Although coexpression of EGFR and EGFRvIII confers a growth advantage, how EGFR and EGFRvIII influence the tumor microenvironment remains incompletely understood. Here, we show that EGFR and EGFRvIII cooperate to induce macrophage infiltration via upregulation of the chemokine CCL2. EGFRvIII was significantly enriched in glioblastoma patient samples with high CCL2, and knockout of CCL2 in tumors coexpressing EGFR and EGFRvIII led to decreased infiltration of macrophages. KRAS was a critical signaling intermediate for EGFR- and EGFRvIII-induced expression of CCL2. Our results illustrate how EGFR and EGFRvIII direct the microenvironment in glioblastoma. SIGNIFICANCE: Full-length EGFR and truncated EGFRvIII work through KRAS to upregulate the chemokine CCL2 and drive macrophage infiltration in glioblastoma

Protection from EAE in DOCK8 mutant mice occurs despite increased Th17 cell frequencies in the periphery

Mutation of Dedicator of cytokinesis 8 (DOCK8) has previously been reported to provide resistance to the Th17 cell dependent EAE in mice. Contrary to expectation, we observed an elevation of Th17 cells in two different DOCK8 mutant mouse strains in the steady state. This was specific for Th17 cells with no change in Th1 or Th2 cell populations. In vitro Th cell differentiation assays revealed that the elevated Th17 cell population was not due to a T cell intrinsic differentiation bias. Challenging these mutant mice in the EAE model, we confirmed a resistance to this autoimmune disease with Th17 cells remaining elevated systemically while cellular infiltration in the CNS was reduced. Infiltrating T cells lost the bias toward Th17 cells indicating a relative reduction of Th17 cells in the CNS and a Th17 cell specific migration disadvantage. Adoptive transfers of Th1 and Th17 cells in EAE‐affected mice further supported the Th17 cell‐specific migration defect, however, DOCK8‐deficient Th17 cells expressed normal Th17 cell‐specific CCR6 levels and migrated toward chemokine gradients in transwell assays. This study shows that resistance to EAE in DOCK8 mutant mice is achieved despite a systemic Th17 bias.This work was supported by an Australian Government Research Training Program Scholarship (A.S.W.), NHMRC project grants 1022922 (K.L.R.) and 1079318 (J.O., K.L.R.), ACT Health Private Practice Fund Major Grant 2015 and 2016 (K.L.R). C.B.K.T. was supported by the DKH (110663) and the BMBF (01ZX1401B). D.B. is funded through the FNR-ATTRACT program (A14/BM/7632103) and an FNR-CORE grant (C15/BM/10355103) of the Luxembourg National Research Fund. The authors thank all members of the Brüstle laboratory, past and present, for their support and the flow cytometry facility at The John Curtin School of Medical Research for their excellent services. The authors further thank Dr. Emmalene Bartlett for her insightful scientific editing

A sensitive and simple targeted proteomics approach to quantify transcription factor and membrane proteins of the unfolded protein response pathway in glioblastoma cells

Many cellular events are driven by changes in protein expression, measurable by mass spectrometry or antibody-based assays. However, using conventional technology, the analysis of transcription factor or membrane receptor expression is often limited by an insufficient sensitivity and specificity. To overcome this limitation, we have developed a high-resolution targeted proteomics strategy, which allows quantification down to the lower attomol range in a straightforward way without any prior enrichment or fractionation approaches. The method applies isotope-labeled peptide standards for quantification of the protein of interest. As proof of principle, we applied the improved workflow to proteins of the unfolded protein response (UPR), a signaling pathway of great clinical importance, and could for the first time detect and quantify all major UPR receptors, transducers and effectors that are not readily detectable via antibody-based-, SRM- or conventional PRM assays. As transcription and translation is central to the regulation of UPR, quantification and determination of protein copy numbers in the cell is important for our understanding of the signaling process as well as how pharmacologic modulation of these pathways impacts on the signaling. These questions can be answered using our newly established workflow as exemplified in an experiment using UPR perturbation in a glioblastoma cell lines

A multi-omics analysis reveals the unfolded protein response regulon and stress-induced resistance to folate-based antimetabolites

Stress response pathways are critical for cellular homeostasis, promoting survival through adaptive changes in gene expression and metabolism. They play key roles in numerous diseases and are implicated in cancer progression and chemoresistance. However, the underlying mechanisms are only poorly understood. We have employed a multi-omics approach to monitor changes to gene expression after induction of a stress response pathway, the unfolded protein response (UPR), probing in parallel the transcriptome, the proteome, and changes to translation. Stringent filtering reveals the induction of 267 genes, many of which have not previously been implicated in stress response pathways. We experimentally demonstrate that UPR-mediated translational control induces the expression of enzymes involved in a pathway that diverts intermediate metabolites from glycolysis to fuel mitochondrial one-carbon metabolism. Concomitantly, the cells become resistant to the folate-based antimetabolites Methotrexate and Pemetrexed, establishing a direct link between UPR-driven changes to gene expression and resistance to pharmacological treatment

Toso controls encephalitogenic immune responses by dendritic cells and regulatory T cells

The ability to mount a strong immune response against pathogens is crucial for mammalian survival. However, excessive and uncontrolled immune reactions can lead to autoimmunity. Unraveling how the reactive versus tolerogenic state is controlled might point toward novel therapeutic strategies to treat autoimmune diseases. The surface receptor Toso/Faim3 has been linked to apoptosis, IgM binding, and innate immune responses. In this study, we used Toso-deficient mice to investigate the importance of Toso in tolerance and autoimmunity. We found that Toso(-/-) mice do not develop severe experimental autoimmune encephalomyelitis (EAE), a mouse model for the human disease multiple sclerosis. Toso(-/-) dendritic cells were less sensitive to Toll-like receptor stimulation and induced significantly lower levels of disease-associated inflammatory T-cell responses. Consistent with this observation, the transfer of Toso(-/-) dendritic cells did not induce autoimmune diabetes, indicating their tolerogenic potential. In Toso(-/-) mice subjected to EAE induction, we found increased numbers of regulatory T cells and decreased encephalitogenic cellular infiltrates in the brain. Finally, inhibition of Toso activity in vivo at either an early or late stage of EAE induction prevented further disease progression. Taken together, our data identify Toso as a unique regulator of inflammatory autoimmune responses and an attractive target for therapeutic intervention

RhoA regulates translation of the Nogo-A decoy SPARC in white matter-invading glioblastomas

Glioblastomas strongly invade the brain by infiltrating into the white matter along myelinated nerve fiber tracts even though the myelin protein Nogo-A prevents cell migration by activating inhibitory RhoA signaling. The mechanisms behind this long-known phenomenon remained elusive so far, precluding a targeted therapeutic intervention. This study demonstrates that the prevalent activation of AKT in gliomas increases the ER protein-folding capacity and enables tumor cells to utilize a side effect of RhoA activation: the perturbation of the IRE1 alpha-mediated decay of SPARC mRNA. Once translation is initiated, glioblastoma cells rapidly secrete SPARC to block Nogo-A from inhibiting migration via RhoA. By advanced ultramicroscopy for studying single-cell invasion in whole, undissected mouse brains, we show that gliomas require SPARC for invading into white matter structures. SPARC depletion reduces tumor dissemination that significantly prolongs survival and improves response to cytostatic therapy. Our finding of a novel RhoA-IRE1 axis provides a druggable target for interfering with SPARC production and underscores its therapeutic value