cIMPACT-NOW update 11: Proposal on adaptation of diagnostic criteria for IDH- and H3-wildtype diffuse high-grade gliomas and for posterior fossa ependymal tumors.

The Consortium to Inform Molecular and Practical Approaches to Central Nervous System Tumor Taxonomy (cIMPACT-NOW) updates provide guidelines for the diagnosis of central nervous system (CNS) tumors and suggestions for future World Health Organization (WHO) classification. Following publication of the fifth edition WHO Classification of CNS Tumors (WHO CNS5) in 2021, the cIMPACT-NOW working group "Clarification" reviewed WHO CNS5 and prioritized two topics for further elucidation: (a) distinction of Glioblastoma, IDH-wildtype from Diffuse pediatric-type high-grade glioma, H3-wildtype, and IDH-wildtype and (b) clarification of subgroups of posterior fossa (PF) ependymal tumors. Recommendations regarding the IDH- and H3-wildtype diffuse high-grade gliomas include: (1) use caution assigning CNS WHO grade 4 (diagnosis of Glioblastoma, IDH-wildtype) to a "TERT promoter only", histologically low-grade, IDH-wildtype tumor; (2) EGFR gene amplification and +7/-10 chromosome copy number alterations should not be used as solitary defining features for diagnosing high-grade gliomas as Glioblastoma, IDH-wildtype in patients <40 years of age; (3) Diffuse pediatric-type high-grade glioma, H3-wildtype, and IDH-wildtype should be considered in the differential diagnosis in adults, especially those <40 years of age; (4) PDGFRA alteration, EGFR alteration, or MYCN amplification count as key molecular features of Diffuse pediatric-type high-grade glioma, H3-wildtype, and IDH-wildtype only in patients <25 years.

Molecular, histologic, and clinical characterization of methylation class pleomorphic xanthoastrocytoma: An analysis of 469 tumors.

Background: Methylation class pleomorphic xanthoastrocytoma (mcPXA) comprises tumors with the DNA methylation signature of classical PXA but with a wider histologic spectrum, including overlap with glioblastoma (GBM).

Methods: To clarify the histologic and molecular scope of mcPXA and characterize its clinical behavior, a cohort of 469 tumor samples from 458 patients matching to mcPXA by the DKFZ classifier (v12.6 score ≥0.

The EIF4EBP1 gene encoding 4EBP1 is transcriptionally upregulated by MYC and linked to shorter survival in medulloblastoma.

Medulloblastoma (MB) is the most common malignant brain tumor in childhood and is stratified into four molecular groups ‒ Wingless and Int-1 (WNT), Sonic hedgehog (SHH), Group 3 and Group 4. Group 3 MB patients exhibit the poorest prognosis, with a 5-year overall survival of <60%, followed by Group 4 MB patients. Apart from MYC amplification in a subset of Group 3 MBs, the molecular pathomechanisms driving aggressiveness of these tumors remain incompletely characterized.

Anatomic Staging of H3 G34-Mutant Diffuse Hemispheric Glioma.

Objectives: H3 G34-mutant diffuse hemispheric gliomas are rare, aggressive primary brain tumors predominantly affecting young patients. We investigated the prognostic value of anatomic staging (AS)-a system previously validated in adult-type diffuse gliomas-in this molecularly distinct tumor type.

Methods: Patients from an international cohort with H3 G34-mutant gliomas underwent AS based on pretreatment imaging, performed independently by 2 raters blinded to clinical outcomes.

Advancing CNS tumor diagnostics with expanded DNA methylation-based classification.

DNA methylation-based classification is integral to contemporary neuro-oncological diagnostics, as highlighted by the current World Health Organization (WHO) classification of central nervous system (CNS) tumors. We introduce the Heidelberg CNS Tumor Methylation Classifier version 12.8 (v12.

Identification and characterization of tertiary lymphoid structures in brain metastases.

Brain metastases (BrM) are the most common cancers in the brain and linked to poor prognosis. Given the high incidence and often limited treatment options, understanding the complexity of the BrM tumor microenvironment is crucial for the development of novel therapeutic strategies. We performed transcriptome-wide gene expression profiling combined with spatial immune cell profiling to characterize the tumor immune microenvironment in 95 patients with BrM from different primary tumors.

Strong nuclear expression of HOXB13 is a reliable surrogate marker for DNA methylome profiling to distinguish myxopapillary ependymoma from spinal ependymoma.

Spinal ependymoma and myxopapillary ependymoma are the two most common spinal ependymal tumor types that feature distinct histological characteristics, genetic alterations and DNA methylation profiles. Their histological distinction may be difficult in individual cases and molecular diagnostic assessment, in particular DNA methylome profiling, may then be required to assign the correct diagnosis. Expression of the homeobox gene HOXB13 at the mRNA and protein levels has been reported as a frequent finding in myxopapillary ependymoma that may serve as a diagnostic marker for these tumors.

An in vitro pharmacogenomic approach reveals subtype-specific therapeutic vulnerabilities in atypical teratoid/rhabdoid tumors (AT/RT).

Atypical teratoid/rhabdoid tumor (AT/RT) is a highly malignant embryonal brain tumor driven by genetic alterations inactivating the SMARCB1 or, less commonly, the SMARCA4 gene. Large-scale molecular profiling studies have identified distinct molecular subtypes termed AT/RT-TYR, -SHH and -MYC. Despite the increasing knowledge of AT/RT biology, curative treatment options are still lacking for certain risk groups and outcomes of these patients remain poor.

IDH-mutant astrocytomas with primitive neuronal component have a distinct methylation profile and a higher risk of leptomeningeal spread.

IDH-mutant astrocytomas are diffuse gliomas that are defined by characteristic mutations in IDH1 or IDH2 and do not have complete 1p/19q co-deletion. The established grading criteria include histological features of brisk mitotic activity (grade 3) and necrosis and/or microvascular proliferation (grade 4). In addition, homozygous deletion of the CDKN2A/B locus has recently been implemented as a molecular marker for grade 4 IDH-mutant astrocytomas.

The clinical and molecular landscape of diffuse hemispheric glioma, H3 G34-mutant.

Background: Diffuse hemispheric glioma, histone 3 (H3) G34-mutant, has been newly defined in the 2021 World Health Organization (WHO) classification of central nervous system tumors. Here we sought to define the prognostic roles of clinical, neuroimaging, pathological, and molecular features of these tumors.

Methods: We retrospectively assembled a cohort of 114 patients (median age 22 years) with diffuse hemispheric glioma, H3 G34-mutant, central nervous system WHO grade 4, and profiled the imaging, histological, and molecular landscape of their tumors.

Prognostic factors for overall survival in elderly patients with glioblastoma: Analysis of the pooled NOA-08 and Nordic trials with the CCTG-EORTC (CE.6) trial.

Background: The majority of patients diagnosed with glioblastoma are >60 years. Three randomized trials addressed the roles of radiotherapy (RT) and temozolomide (TMZ) for elderly patients. NORDIC and NOA-08 compared RT versus TMZ, while CE.

European Association of Neuro-Oncology guideline on molecular testing of meningiomas for targeted therapy selection.

Meningiomas are the most common primary intracranial tumors of adults. For meningiomas that progress or recur despite surgical resection and radiotherapy, additional treatment options are limited due to a lack of proven efficacy. Meningiomas show recurring molecular aberrations, which may serve as predictive markers for systemic pharmacotherapies with targeted drugs or immunotherapy, radiotherapy, or radioligand therapy.

HERV-W envelope protein is present in microglial cells of the human glioma tumor microenvironment and differentially modulates neoplastic cell behavior.

Gliomas are the most common parenchymal tumors of the central nervous system (CNS). With regard to their still unclear etiology, several recent studies have provided evidence of a new category of pathogenic elements called human endogenous retroviruses (HERVs) which seem to contribute to the evolution and progression of many neurological diseases such as amyotrophic lateral sclerosis (ALS), schizophrenia, chronic inflammatory polyneuropathy (CIDP) and, particularly, multiple sclerosis (MS). In these diseases, HERVs exert effects on cellular processes such as inflammation, proliferation, and migration.

Flow cytometry identifies changes in peripheral and intrathecal lymphocyte patterns in CNS autoimmune disorders and primary CNS malignancies.

Background: Immune dysregulation is a hallmark of autoimmune diseases of the central nervous system (CNS), characterized by an excessive immune response, and primary CNS tumors (pCNS-tumors) showing a highly immunosuppressive parenchymal microenvironment.

Methods: Aiming to provide novel insights into the pathogenesis of CNS autoimmunity and cerebral tumor immunity, we analyzed the peripheral blood (PB) and cerebrospinal fluid (CSF) of 81 autoimmune limbic encephalitis (ALE), 148 relapsing-remitting multiple sclerosis (RRMS), 33 IDH-wildtype glioma, 9 primary diffuse large B cell lymphoma of the CNS (CNS-DLBCL), and 110 controls by flow cytometry (FC). Additionally, an in-depth immunophenotyping of the PB from an independent cohort of 20 RRMS and 18 IDH-wildtype glioblastoma patients compared to 19 controls was performed by FC combined with unsupervised computational approaches.

The oncological role of resection in newly diagnosed diffuse adult-type glioma defined by the WHO 2021 classification: a Review by the RANO resect group.

Glioma resection is associated with prolonged survival, but neuro-oncological trials have frequently refrained from quantifying the extent of resection. The Response Assessment in Neuro-Oncology (RANO) resect group is an international, multidisciplinary group that aims to standardise research practice by delineating the oncological role of surgery in diffuse adult-type gliomas as defined per WHO 2021 classification. Favourable survival effects of more extensive resection unfold over months to decades depending on the molecular tumour profile.

A clinically compatible in vitro drug-screening platform identifies therapeutic vulnerabilities in primary cultures of brain metastases.

Purpose: Brain metastases represent the most common intracranial tumors in adults and are associated with a poor prognosis. We used a personalized in vitro drug screening approach to characterize individual therapeutic vulnerabilities in brain metastases.

Methods: Short-term cultures of cancer cells isolated from brain metastasis patients were molecularly characterized using next-generation sequencing and functionally evaluated using high-throughput in vitro drug screening to characterize pharmacological treatment sensitivities.

mTORC1 regulates cell survival under glucose starvation through 4EBP1/2-mediated translational reprogramming of fatty acid metabolism.

Energetic stress compels cells to evolve adaptive mechanisms to adjust their metabolism. Inhibition of mTOR kinase complex 1 (mTORC1) is essential for cell survival during glucose starvation. How mTORC1 controls cell viability during glucose starvation is not well understood.

Glioma.

Gliomas are primary brain tumours that are thought to develop from neural stem or progenitor cells that carry tumour-initiating genetic alterations. Based on microscopic appearance and molecular characteristics, they are classified according to the WHO classification of central nervous system (CNS) tumours and graded into CNS WHO grades 1-4 from a low to high grade of malignancy. Diffusely infiltrating gliomas in adults comprise three tumour types with distinct natural course of disease, response to treatment and outcome: isocitrate dehydrogenase (IDH)-mutant and 1p/19q-codeleted oligodendrogliomas with the best prognosis; IDH-mutant astrocytomas with intermediate outcome; and IDH-wild-type glioblastomas with poor prognosis.

Epigenetic modification and characterization of the promoter region using CRISPRoff in glioblastoma cells.

The methylation status of the O6-methylguanine DNA methyltransferase (MGMT) promoter region is a critical predictor of response to alkylating agents in glioblastoma. However, current approaches to study the MGMT status focus on analyzing models with non-identical backgrounds. Here, we present an epigenetic editing approach using CRISPRoff to introduce site-specific CpG methylation in the promoter region of glioma cell lines.

Improved prognostic stratification of patients with isocitrate dehydrogenase-mutant astrocytoma.

Prognostic factors and standards of care for astrocytoma, isocitrate dehydrogenase (IDH)-mutant, CNS WHO grade 4, remain poorly defined. Here we sought to explore disease characteristics, prognostic markers, and outcome in patients with this newly defined tumor type. We determined molecular biomarkers and assembled clinical and outcome data in patients with IDH-mutant astrocytomas confirmed by central pathology review.

Zotiraciclib (TG02) for newly diagnosed glioblastoma in the elderly or for recurrent glioblastoma: The EORTC 1608 STEAM trial.

Background: Zotiraciclib (TG02) is an oral multi-cyclin dependent kinase (CDK) inhibitor thought to inhibit tumor growth via CDK-9-dependent depletion of survival proteins such as c-MYC and MCL-1 which are frequently overexpressed in glioblastoma.

Methods: EORTC 1608 (NCT03224104) (STEAM) had a three parallel group (A,B,C) phase Ib, open-label, non-randomized, multicenter design in IDH wild-type newly diagnosed glioblastoma or anaplastic astrocytoma. Groups A and B explored the maximum tolerated dose (MTD) of TG02 in elderly patients, in combination with hypofractionated radiotherapy alone (group A) or temozolomide alone (group B), according to O-methylguanine DNA methyltransferase promoter methylation status determined centrally.