Abstract Chronic traumatic encephalopathy (CTE) is a tauopathy associated with repetitive head impacts, experienced most commonly in contact sports; however, its relationship with prion diseases remains unclear. Postmortem CTE screening using phosphorylated tau staining was conducted at the Neurological Tissue Bank of Hospital Clínic‐IDIBAPS on hippocampal and frontal cortex samples from patients with neuropathologically confirmed Creutzfeldt–Jakob disease (CJD), blinded to patients' clinical histories. In positive and suggestive cases, the analysis was expanded in accordance with the NINDS/NIBIB consensus criteria for CTE, and clinical and neuropathological information was reviewed. CTE was detected in 3 out of 212 CJD cases (1.4%), all with severe CTE pathology: 2 former soccer players (one of them an elite player) and 1 former rugby player. All had started playing sports between the first and second decades of life and ended in the fifth. The clinical presentation of CJD was heterogeneous, with different initial symptoms in each case. Neuropathological examination revealed an MM1/MV1 histotype in the soccer players and a VV2 histotype in the rugby player, the first‐ and second‐most common variants in CJD, respectively. These three cases illustrate the coexistence of CTE and CJD across heterogeneous clinicopathological presentations. Further studies are needed to determine whether shared mechanisms may contribute to the coexistence of both pathologies.
Tumor treating fields (TTFields) are a treatment for glioblastoma, isocitrate dehydrogenase wildtype (GBM, IDH wt) that improves survival, but no validated biomarkers exist to identify patients likely to benefit. This study aims to identify molecular biomarkers guiding clinical decisions on TTFields initiation. Eighty gliomas treated with surgery, radiochemotherapy, and TTFields were reassessed using DNA methylation profiling and TSO500 DNA/RNA panel sequencing, identifying 64 highly characteristic GBM, IDH wt with comprehensive molecular data. Alterations present in ≥5 cases were analyzed for association with survival using Kaplan-Meier and Cox models. Two TTFields-naïve GBM, IDH wt cohorts (n = 175) served as controls. For 18 cases, post-treatment tissue from a second surgery was profiled. Twenty-four alterations occurred in ≥5 patients. Univariate analyses showed KPS and MGMT promoter methylation as protective, while EGFR amplification, CDKN2A/B loss, and homozygous PTEN deletion were linked to worse survival with TTFields. Multivariate analysis confirmed KPS and MGMT as protective and homozygous PTEN deletion as a risk factor (median OS 368 vs. 603 days; HR 3.86, p = 0.0049). In TTFields-naïve cohorts, homozygous PTEN deletion was not associated with outcome, and frequencies were comparable (controls 7%, TTFields 11%). Post-TTFields GBM, IDH wt did not acquire hypermutation or other recurrent molecular alterations. Alongside the established factors MGMT and KPS, PTEN homozygous deletion was associated with worse survival in GBM, IDH wt patients treated with TTFields. Homozygous PTEN deletion may be associated with reduced benefit from TTFields and should be further investigated as a predictive biomarker for TTFields treatment.
Medulloblastoma is the most common malignant pediatric brain tumor and comprises biologically distinct molecular subgroups with different clinicopathologic and prognostic characteristics. Molecular data from Kazakhstan and other underrepresented regions remain limited, and practical approaches for molecular subgroup assignment using formalin-fixed, paraffin-embedded (FFPE) material are needed in settings where advanced molecular classification is not routinely available. We retrospectively analyzed 40 pediatric medulloblastomas diagnosed between 2015 and 2024 at the Corporate Fund "University Medical Center," Kazakhstan. Archived FFPE tumor material underwent histologic review, immunohistochemical evaluation (β-catenin, YAP1, and GAB1), and whole-exome sequencing. Tumors were assigned to WNT, SHH, or non-WNT/non-SHH categories using a combined morphologic, immunophenotypic, and genomic framework, and clinicopathologic variables and overall survival were evaluated across subgroups. WNT medulloblastomas (n = 7, 17.5%) showed the most canonical profile, characterized by classic histology, uniform β-catenin nuclear positivity, recurrent CTNNB1/APC alterations, and frequent chromosome 6 loss. SHH medulloblastomas (n = 10, 25.0%) were enriched for desmoplastic/nodular morphology, frequent YAP1/GAB1 expression, pathogenic PTCH1/SUFU alterations, and additional events involving TP53, TERT, and focal amplifications in a subset. Non-WNT/non-SHH medulloblastomas (n = 23, 57.5%) showed the greatest genomic heterogeneity, including frequent i17q and broader structural complexity. Clinically, WNT tumors occurred predominantly in older children and had the most favorable survival, whereas non-WNT/non-SHH tumors were the only subgroup associated with metastatic disease at presentation and showed the poorest long-term survival. Overall, pediatric medulloblastoma in this cohort demonstrated subgroup-specific patterns consistent with established biology. The integration of pathology, immunohistochemistry, and sequencing enabled clinically meaningful molecular stratification. These findings expand evidence from an underrepresented setting and support pragmatic, resource-adapted profiling in routine practice.
DNA methylation profiling is an integral diagnostic tool in the classification of central nervous system (CNS) tumors. While the Heidelberg CNS Tumor Methylation Classifier is widely used to support CNS tumor diagnostics, new classifiers such as CrossNN are emerging. However, their clinical performance and added value within routine diagnostic workflows remain insufficiently explored. In this study, we evaluated the diagnostic performance of the CrossNN classifier in a real-world CNS tumor cohort and compared it with the established Heidelberg classifier to assess its potential as both a non-inferior alternative and a complementary tool to improve diagnostic accuracy. A retrospective cohort of CNS tumors profiled using Illumina Human Methylation 930k EPIC v2 BeadChip arrays was analyzed. Classifier outputs were compared with integrated WHO CNS5 (2021) diagnoses. In addition, CrossNN and Heidelberg outputs were harmonized to WHO CNS5 (2021) tumor type levels and evaluated both individually and within sequential and parallel diagnostic workflows. The proposed workflows were subsequently assessed in an independent prospective validation cohort. Among 205 samples, CrossNN correctly classified 88.8% of cases and demonstrated 86.8% concordance with the Heidelberg classifier. CrossNN demonstrated non-inferior classification performance compared with the Heidelberg classifier. Combining both classifiers increased the number of clinically informative and correct classifications by nearly 10%. This finding was confirmed in an independent validation cohort of 41 samples. In conclusion, these results demonstrate the complementary strength of the CrossNN and Heidelberg classifiers as a dual-classifier strategy to improve diagnostic confidence and accuracy in routine CNS tumor diagnostics.
