Distinct molecular profile and outcome of oligodendroglioma, IDH-mutant, 1p/19q-codeleted, and TERTp-wildtype: A grade 1 oligodendroglioma of young patients?

Filippo Nozzoli; Ramin Rahmanzade; Simone Schmid; Leonille Schweizer; Daniel Schrimpf; Dennis Friedel; Kirsten Göbel; David E Reuss; Rouzbeh Banan; Philipp Sievers; Stefan Pusch; Henri Bogumil; Felix Hinz; Abigail K Suwala; Fuat Kaan Aras; Lukas Friedrich; Simona Osella-Abate; Alessia Andrea Ricci; Alessandra Macciotta; Thorsten Simon; Gudrun Fleischhack; Kathy Keyvani; Jordan R Hansford; Dong-Anh Khuong-Quang; Philippe Schucht; Theoni Maragkou; Tareq A Juratli; Matthias Meinhardt; Sabrina Zechel; Christine Stadelmann; Roland Coras; Oliver W Sakowitz; Benjamin Goeppert; Jens Schittenhelm; Nima Etminan; Miriam Ratliff; Christel Herold-Mende; Stefan M Pfister; Wolfgang Wick; Sandro M Krieg; Andreas von Deimling; Felix Sahm; Luca Bertero

doi:10.1093/neuonc/noaf141

. 2025 Jul 19;27(10):2711–2725. doi: 10.1093/neuonc/noaf141

Distinct molecular profile and outcome of oligodendroglioma, IDH-mutant, 1p/19q-codeleted, and TERTp-wildtype: A grade 1 oligodendroglioma of young patients?

Filippo Nozzoli ^1,^2,^#, Ramin Rahmanzade ^3,^4,^5,^#, Simone Schmid ^6,⁷, Leonille Schweizer ^8,^9,¹⁰, Daniel Schrimpf ¹¹, Dennis Friedel ¹², Kirsten Göbel ¹³, David E Reuss ^14,¹⁵, Rouzbeh Banan ^16,¹⁷, Philipp Sievers ^18,¹⁹, Stefan Pusch ^20,²¹, Henri Bogumil ^22,²³, Felix Hinz ^24,²⁵, Abigail K Suwala ^26,²⁷, Fuat Kaan Aras ^28,²⁹, Lukas Friedrich ^30,³¹, Simona Osella-Abate ³², Alessia Andrea Ricci ³³, Alessandra Macciotta ³⁴, Thorsten Simon ³⁵, Gudrun Fleischhack ³⁶, Kathy Keyvani ³⁷, Jordan R Hansford ^38,^39,⁴⁰, Dong-Anh Khuong-Quang ^41,⁴², Philippe Schucht ⁴³, Theoni Maragkou ⁴⁴, Tareq A Juratli ⁴⁵, Matthias Meinhardt ⁴⁶, Sabrina Zechel ⁴⁷, Christine Stadelmann ⁴⁸, Roland Coras ⁴⁹, Oliver W Sakowitz ⁵⁰, Benjamin Goeppert ^51,⁵², Jens Schittenhelm ⁵³, Nima Etminan ⁵⁴, Miriam Ratliff ⁵⁵, Christel Herold-Mende ⁵⁶, Stefan M Pfister ^57,^58,^59,⁶⁰, Wolfgang Wick ^61,⁶², Sandro M Krieg ⁶³, Andreas von Deimling ^64,⁶⁵, Felix Sahm ^66,^67,^68,^4,^✉, Luca Bertero ^69,^70,^4,^✉

¹ Histopathology and Molecular Diagnostics, Careggi University Hospital, Florence, Italy

² Section of Anatomic Pathology, Department of Health Sciences, University of Florence, Florence, Italy

³ Clinical Cooperation Unit Neuropathology, German Consortium for Translational Cancer Research (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany

⁴ Department of Neuropathology, Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany

⁵ Institute of Pathology, Ludwig Maximilians University Hospital Munich, Munich, Germany

⁶ German Cancer Consortium (DKTK), Partner Site Berlin, and German Cancer Research Center (DKFZ), Heidelberg, Germany

⁷ Department of Neuropathology, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt—Universität zu Berlin, Berlin, Germany

⁸ German Cancer Consortium (DKTK), Partner Site Frankfurt/Mainz, German Cancer Research Center (DKFZ), Heidelberg, Germany

⁹ Frankfurt Cancer Institute (FCI), Frankfurt am Main, Germany

¹⁰ Institute of Neurology (Edinger Institute), University Hospital Frankfurt, Goethe University, Frankfurt am Main, Germany

¹¹ Department of Neuropathology, Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany

¹² Department of Neuropathology, Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany

¹³ Department of Neuropathology, Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany

¹⁴ Clinical Cooperation Unit Neuropathology, German Consortium for Translational Cancer Research (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany

¹⁵ Department of Neuropathology, Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany

¹⁶ Clinical Cooperation Unit Neuropathology, German Consortium for Translational Cancer Research (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany

¹⁷ Department of Neuropathology, Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany

¹⁸ Clinical Cooperation Unit Neuropathology, German Consortium for Translational Cancer Research (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany

¹⁹ Department of Neuropathology, Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany

²⁰ Clinical Cooperation Unit Neuropathology, German Consortium for Translational Cancer Research (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany

²¹ Department of Neuropathology, Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany

²² Clinical Cooperation Unit Neuropathology, German Consortium for Translational Cancer Research (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany

²³ Department of Neuropathology, Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany

²⁴ Clinical Cooperation Unit Neuropathology, German Consortium for Translational Cancer Research (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany

²⁵ Department of Neuropathology, Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany

²⁶ Clinical Cooperation Unit Neuropathology, German Consortium for Translational Cancer Research (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany

²⁷ Department of Neuropathology, Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany

²⁸ Clinical Cooperation Unit Neuropathology, German Consortium for Translational Cancer Research (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany

²⁹ Department of Neuropathology, Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany

³⁰ Clinical Cooperation Unit Neuropathology, German Consortium for Translational Cancer Research (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany

³¹ Department of Neuropathology, Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany

³² Pathology Unit, Città della Salute e della Scienza University Hospital, Turin, Italy

³³ Pathology Unit, Department of Medical Sciences, University of Turin, Turin, Italy

³⁴ Department of Medical Sciences, University of Turin and CPO Piemonte, Turin, Italy

³⁵ Department of Pediatric Oncology and Hematology, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany

³⁶ Pediatric Hematology and Oncology, Pediatrics III, University Children’s Hospital of Essen, Essen, Germany

³⁷ Institute of Neuropathology, University of Duisburg-Essen, Essen, Germany

³⁸ South Australia Immunogenomics Cancer Institute, University of Adelaide, Adelaide, South Australia, Australia

³⁹ South Australia Health and Medical Research Institute, Adelaide, South Australia, Australia

⁴⁰ Michael Rice Centre for Hematology and Oncology, Women’s and Children’s Hospital, Adelaide, South Australia, Australia

⁴¹ Children’s Cancer Centre, Royal Children’s Hospital Melbourne, Melbourne, Victoria, Australia

⁴² Department of Pediatrics, Murdoch Children’s Research Institute, University of Melbourne, Melbourne, Victoria, Australia

⁴³ Department of Neurosurgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland

⁴⁴ Institute of Tissue Medicine and Pathology, University of Bern, Bern, Switzerland

⁴⁵ Department of Neurosurgery, Division of Neuro-Oncology, Faculty of Medicine, Carl Gustav Carus University Hospital, TU Dresden, Dresden, Germany

⁴⁶ Department of Pathology, Faculty of Medicine and Carl Gustav Carus University Hospital, TU Dresden, Dresden, Germany

⁴⁷ Department of Neuropathology, University Medical Center Göttingen, Göttingen, Germany

⁴⁸ Department of Neuropathology, University Medical Center Göttingen, Göttingen, Germany

⁴⁹ Department of Neuropathology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany

⁵⁰ Institute of Pathology and Neuropathology, RKH Klinikum Ludwigsburg, Ludwigsburg, Germany

⁵¹ Institute of Pathology and Neuropathology, RKH Klinikum Ludwigsburg, Ludwigsburg, Germany

⁵² Institute of Tissue Medicine and Pathology, University of Bern, Bern, Switzerland

⁵³ Department of Neuropathology, Institute of Pathology and Neuropathology, University Hospital of Tübingen, Tübingen, Germany

⁵⁴ Department of Neurosurgery, University Hospital Mannheim, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany

⁵⁵ Department of Neurosurgery, University Hospital Mannheim, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany

⁵⁶ Division of Experimental Neurosurgery, Department of Neurosurgery, Heidelberg University Hospital, Heidelberg, Germany

⁵⁷ Division of Pediatric Neuro-Oncology (B062), German Cancer Research Center (DKFZ) and German Cancer Consortium (DKTK), Heidelberg, Germany

⁵⁸ National Center for Tumor Diseases (NCT), Heidelberg, Germany

⁵⁹ Department of Pediatric Hematology and Oncology, Heidelberg University Hospital, Heidelberg, Germany

⁶⁰ Hopp Children’s Cancer Center (KiTZ), Heidelberg, Germany

⁶¹ Department of Neurology and Neurooncology Program, National Center for Tumor Diseases, Heidelberg University Hospital, Heidelberg, Germany

⁶² Clinical Cooperation Unit Neurooncology, German Cancer Research Center (DKFZ), Heidelberg, Germany

⁶³ Department of Neurosurgery, Heidelberg University Hospital, Heidelberg, Germany

⁶⁴ Clinical Cooperation Unit Neuropathology, German Consortium for Translational Cancer Research (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany

⁶⁵ Department of Neuropathology, Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany

⁶⁶ CCU Neuropathology, German Consortium for Translational Cancer Research (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany

⁶⁷ Clinical Cooperation Unit Neuropathology, German Consortium for Translational Cancer Research (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany

⁶⁸ Department of Neuropathology, Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany

⁶⁹ Pathology Unit, Department of Medical Sciences, University of Turin, Turin, Italy

⁷⁰ Pathology Unit, Città della Salute e della Scienza University Hospital, Turin, Italy

^✉

Corresponding author: Luca Bertero, MD, PhD, Pathology Unit, Department of Medical Sciences, University of Turin, Via Santena 7, 10126 Turin, Italy (luca.bertero@unito.it)

^✉

Corresponding author: Felix Sahm, MD, PhD, Department of Neuropathology, University Hospital Heidelberg and, Clinical Cooperation Unit Neuropathology (B300), German Cancer Research Center (DKFZ), Im Neuenheimer Feld 224, 69120 Heidelberg, Germany (felix.sahm@med.uni-heidelberg.de).

Filippo Nozzoli and Ramin Rahmanzade contributed equally to this work and share first authorship.

⁴

Felix Sahm and Luca Bertero share corresponding and senior authorship.

PMCID: PMC12833541 PMID: 40692489

Abstract

Background

Oligodendrogliomas, characterized by isocitrate dehydrogenase (IDH) mutations and 1p/19q codeletion, often exhibit telomerase reverse transcriptase promoter (TERTp) mutations, which have been linked to telomere maintenance (TM) and tumor proliferation. Although there are a few reports on a TERTp-wildtype subset of these tumors in adolescents and young adults, the frequency, molecular characteristics, and prognostic implications of TERTp-wildtype status in oligodendrogliomas remain elusive.

Methods

We retrospectively analyzed 166 IDH-mutant and 1p/19q-codeleted oligodendroglioma cases through comprehensive histopathological review and molecular analyses, including Sanger sequencing, DNA methylation profiling, and whole-exome sequencing (WES).

Results

A TERTp-wildtype status was observed in 20/166 cases (12.0%) and was significantly associated with noticeably young age (age range: 14–27, P < .001), CNS WHO grade 2 (P = .003), and the absence of additional DNA copy number variations (CNVs) beyond the pathognomonic 1p/19q codeletion (P < .001). Epigenetic profiling demonstrated TERTp-wildtype tumors shaped a distinct subgroup at the utmost periphery of TERTp-mutant oligodendrogliomas. Methylation analysis of the upstream and proximal TERTp regions revealed that, in line with the absence of genetic alterations, epigenetic regulation does not favor TERT overexpression in TERTp-wildtype oligodendrogliomas. WES showed no TM-related gene alterations in TERTp-wildtype cases. Cox regression analysis confirmed TERTp-wildtype status as an independent prognostic factor for more favorable progression-free survival (PFS) (P = .009).

Conclusions

In conclusion, “oligodendroglioma, IDH-mutant, 1p/19q-codeleted, and TERTp-wildtype” represent a distinct molecular subgroup associated with younger age and a better clinical course compared to CNS WHO grade 2 oligodendrogliomas.

Keywords: adolescents and young adults, methylation, oligodendroglioma, progression-free survival, TERT promoter

Key Points.

Telomerase reverse transcriptase promoter promoter (TERTp)-wildtype status is significantly associated with young age in oligodendroglioma.
Molecular profiling identifies TERTp-wildtype oligodendrogliomas as a distinct subgroup.
TERTp-wildtype status is an independent prognostic factor for more favorable PFS.

Importance of the Study.

Oligodendrogliomas, IDH-mutant, 1p/19q-codeleted frequently harbor telomerase reverse transcriptase promoter (TERTp) mutations, critical in telomere maintenance and tumorigenesis. However, a subset that lacks TERTp mutations, particularly in adolescents and young adults, remains poorly understood, with limited insights into its frequency, molecular characteristics, and clinical implications. This study bridges this knowledge gap by providing a comprehensive analysis of TERTp-wildtype oligodendrogliomas, including a relevant cohort of young patients. Through comprehensive molecular profiling, our data identify TERTp-wildtype status as a distinct molecular subgroup linked to younger age and improved prognosis. Our findings reveal the absence of typical telomere maintenance alterations and a distinct epigenetic profile, positioning TERTp-wildtype oligodendrogliomas as a low-risk group. These insights have the potential to refine prognostic classifications and lead to more tailored management strategies for younger oligodendroglioma patients.

According to the fifth edition of the WHO Classification of the CNS Tumours,¹ the molecular entity-defining alterations in oligodendrogliomas include missense mutations in IDH1 codon 132 or IDH2 codon 172, combined with whole-arm deletions of 1p and 19q. Other nonessential diagnostic requirements, but frequent genetic hallmarks include capicua (CIC), far upstream element binding protein 1 (FUBP1), and telomerase reverse transcriptase promoter (TERTp) mutations, as well as the absence of alpha-thalassemia mental retardation X-linked (ATRX), and tumor protein 53 (TP53) alterations.²

Telomere maintenance (TM) is a key event in glioma development^3,4 and is believed to be usually achieved by 2 different pathways: (1) activation of TERT through promoter mutation that recruits de novo E26 transformation-specific transcription factor binding sites, which leads to transcriptional upregulation of TERT expression driving telomere stabilization, cellular immortalization, and proliferation,^3,5,6 or (2) a telomerase-independent mechanism known as alternative lengthening of telomeres, which relies on the homologous recombination of telomeric regions, resulting in heterogeneous length and sequence composition, and it is commonly reflected by ATRX mutation.^7,8 Unlike IDH-mutant astrocytomas,⁹ the vast majority of IDH-mutant and 1p/19q-codeleted oligodendrogliomas are nonmutated for ATRX,¹⁰ while over 90% of them harbor TERTp hotspot mutations.^11–16 A recent whole-tumor analysis⁷ also showed TERTp mutation to be an early and clonal event in oligodendroglioma genesis, which remains stable during tumor progression and at recurrence.¹⁷

Although TERTp mutations are widely observed in oligodendroglioma, Lee et al.¹⁸ described a case series of 3 IDH-mutant and 1p/19q-codeleted oligodendrogliomas who lacked TERTp mutation, typically found in adult cases. Reviewing data from major pediatric low-grade glioma genomics studies,^19–22 just a few additional cases of IDH-mutant and 1p/19q-codeleted oligodendrogliomas with confirmed TERTp-wildtype status have been reported.^19,20 In older studies and population-based registries, the TERTp mutation rate of histologically defined tumors is confounded by the inclusion of gliomas lacking IDH mutation and/or 1p/19q codeletion.²³

The prognostic impact of TERTp mutations in diffuse gliomas is bivalent, depending on IDH status and tumor grade,¹² while its significance in conjunction with 1p/19q codeletion remains controversial and largely unknown.^15,24 Additionally, since TERTp mutations are almost universally found in IDH-mutant, 1p/19q-codeleted oligodendrogliomas,¹⁵ our understanding of the molecular characteristics and clinical behavior of TERTp-wildtype cases is still extremely limited.^14,25

To address this, we assessed the frequency, molecular characteristics, and the clinical behavior of TERTp-wildtype oligodendrogliomas through comprehensive histopathological, clinical, and molecular analyses, including Sanger sequencing, DNA methylation profiling, copy number variation (CNV) analysis, and whole-exome sequencing (WES).

Materials and Methods

Collection of Tissue Samples and Clinical Data

A total of 166 cases of oligodendroglioma, IDH-mutant, and 1p/19q-codeleted, were included in this study. The experimental design followed these inclusion criteria: (a) newly diagnosed oligodendrogliomas, IDH-mutant, and 1p/19q-codeleted, between 2004 and 2024; (b) diagnosis confirmed by DNA methylation analysis; (c) molecular confirmation of whole-arm deletions of 1p and 19q; (d) availability of formalin-fixed, paraffin-embedded (FFPE) tissue samples; and (e) availability of clinical follow-up data.

The above-mentioned inclusion criteria have been applied to all cases present within the Biomaterial Bank Heidelberg (BMBH), which stores samples related to both internal cases and those from other national and international institutions that have sent samples over time for diagnostic purposes, additional molecular testing, or second opinion.

The collection and analysis of tissue samples and clinical data were conducted in accordance with the principles of the Declaration of Helsinki.

Histology and Immunohistochemistry

All cases underwent histological review according to the most recent WHO Classification of Tumours of the Central Nervous System (CNS5).¹ Histological features with established prognostic significance, including mitotic activity (counted in 10 high-power fields [HPFs] with a total area of 2.4 mm²), as well as the presence of necrosis and microvascular proliferation, were assessed in all cases. Tumor paraffin blocks were subjected to immunohistochemical workup. Hematoxylin and eosin staining was performed according to standard protocols. The following antibodies for immunohistochemistry were used: GFAP (mouse monoclonal, clone GA5, dilution 1:2000, Cell Signaling), IDH1-R132H (mouse monoclonal, clone H09, Dianova), ATRX (mouse monoclonal, clone BSB-108, dilution 1:2000, Bio SB), Ki-67 (mouse monoclonal, clone MIB-1, dilution 1:100). For ATRX and Ki-67, the Ventana OptiView DAB IHC Detection Kit (Ventana Medical Systems) was used.

TERTp Sanger Sequencing

DNA was extracted from FFPE samples at the Department of Neuropathology, University Hospital Heidelberg, for all cases except 1, for which extracted tumor DNA was provided by the University Hospital Frankfurt. TERTp Sanger sequencing was performed on all oligodendrogliomas with unknown TERTp status at the Department of Neuropathology, University Hospital Heidelberg. Furthermore, to investigate whether TERTp status can be different during tumor progression, we analyzed all the recurrent and surgically treated TERTp-mutant cases with available both primary and recurrent tumor FFPE samples (n = 6).

DNA Methylation Profiling, DNA Methylation Analysis of TERTp and HOXD12, and Copy Number Analysis

Genome-wide DNA methylation data were obtained using the Infinium Methylation EPICv2 (935k) in 16 cases (9.6%), EPICv1 (850k) in 98 cases (59.0%), and the Infinium HumanMethylation450 (450k) BeadChip array in 52 cases (31.4%), following the manufacturer’s instructions (Illumina), as previously described.²⁶ To integrate methylation data across different array versions, we processed raw signal intensities using the R package minfi for background correction and normalization. To minimize technical batch effects across Infinium 450k, EPICv1 (850k), and EPICv2 (935k) arrays, we applied the swan (Subset-quantile Within Array Normalization) method. Only probes common to all 3 platforms were included for downstream analysis. Additionally, beta values were normalized using functional normalization (FunNorm). These adjustments ensure robust comparability across datasets. The DNA methylation-based diagnostic validation of the study cases was performed using the Heidelberg Classifier (version 12.8, available at https://www.molecularneuropathology.org/mnp/). This classifier algorithm facilitates the rapid comparison of diagnostic cases with a reference cohort of more than 2800 cases and is based on the Random Forest algorithm, as previously published.²⁶ The output of the classifier is a tumor methylation class with an associated classification score that reflects the similarity to one of the predefined CNS tumor classes. Each class receives a score ranging from 0 to 1, with all class prediction scores summing to 1. A confident classification requires a methylation class score equal to or above the cutoff of 0.90.²⁶ Copy number profiles were generated from 450k and EPIC methylation arrays data using the conumee Bioconductor package version 1.12.0, as described before.^26,27 All computational analyses were conducted in R version 3.6.0 (R Development Core Team 2016, https://www.R-project.org). Copy number profiles were visually inspected to evaluate chromosomal gains and losses.^28,29 Alterations in key glioma-related genes—including CCND1, CCND2, CDK4, CDK6, CDKN2A/B, EGFR, MDM4, MET, MYC, MYCN, NF1, NF2, PDGFRA, PPM1D, PTEN, RB1, and SMARCB1—were assessed both through visual inspection and analysis using our proprietary algorithm. This algorithm outputs chromosomal status as balanced, gained, or lost, along with the affected region size (percentage) and the amplitude of the alterations in the listed genes. The specific genes and cutoff values have been previously published.²⁹ The b-values of 4 CpGs within upstream TERTp (cg11625005, cg07380026, cg17166338, cg26006951) and 1 CpG within proximal TERTp (cg10896616), covered by all arrays, were subsequently extracted. Recent studies have shown that the methylation status of 3 CpGs within the HOXD12 gene (cg23130254, cg03964958, cg03371669) significantly correlates with HOXD12 expression levels, age, and prognosis in oligodendrogliomas.³⁰ The beta value of cg23130254, covered by all arrays (450k, 850k, and EPICv2), was analyzed accordingly.

WES and Telomere Maintenance-Related Genes Mutational Analysis

Following TERTp Sanger sequencing, oligodendrogliomas with TERTp-wildtype status underwent further genetic analysis of tumor DNA by WES with SureSelect Human All Exon V8 (Agilent) on an Illumina NovaSeq platform (Illumina). The kit targets the most up-to-date protein-coding regions from RefSeq, GENCODE, and CCDS, including the TERTp region. WES data were analyzed for brain tumors and TM-related genes, applying an in-silico panel listed in Supplementary Table 1. Genes of interest for TM were selected based on the TelNet Database,³¹ a source provided by the German Cancer Research Center (DKFZ), which integrates information on TM-relevant genes and their specific cellular functions.

Statistical Analysis

Variables were summarized descriptively, namely median (range) for continuous variables and number (percentage) for categorical data. The association of clinicopathological parameters was analyzed through Mann–Whitney U test for continuous variables and Fisher’s exact test for categorical variables. The prognostic value of clinically and pathologically relevant variables was assessed using univariate and multivariate Cox proportional hazards regression models (the latter applied to variables significant in univariate analysis) and expressed as hazard ratio (HR), adjusted HR (aHR), and 95% confidence interval (CI). The Kaplan–Meier (KM) method was used to estimate progression-free survival (PFS) probabilities, and differences were assessed using the log-rank test. PFS refers to the time from first diagnosis to the first documented disease progression, as evaluated in accordance with the Response Assessment in Neuro-Oncology criteria.³² Further additional univariable and multivariable linear regression models were performed to investigate the association between TERTp status and HOXD12 methylation. All the data were analyzed using GraphPad Prism 10.3.0 (GraphPad Software). All statistical tests were 2-sided, and P < .05 was considered significant.

Results

Demographic and Clinical Characteristics of the Whole Cohort

A total of 166 IDH-mutant and 1p/19q-codeleted oligodendrogliomas were included in the study, comprising 105 males (63.3%), with a median age at diagnosis of 39 years (range: 14–79). The cohort was distributed across the following age groups: 84 patients (50.6%) aged 14–39 years and 82 patients (49.4%) aged 40–79 years. The majority of tumors were located in the frontal lobe (105 patients, 63.3%). Gross-total resection (GTR) was achieved in 72 patients (43.4%). Adjuvant radiation therapy and/or chemotherapy regimens were administered to 89 patients (53.6%), while a “watch-and-wait” approach was applied in 77 patients (46.4%). Baseline clinical and pathological characteristics are provided in Table 1. A flowchart outlining the cohort and the experimental design is presented in Supplementary Figure 1.

Table 1.

Baseline Characteristics of the Whole Cohort and According to TERTp Status

Variables	All patients (n = 166)	TERTp-wildtype (n = 20)	TERTp-mutant (n = 146)	P-value
Age Median (range)	39 (14–79)	17 (14–27)	41 (14–79)	<.001
Age range (years), n (%) 14–39 40–79	84 (50.6) 82 (49.4)	20 (100) 0 (0)	64 (43.8) 82 (56.2)	<.001
Gender, n (%) Male	105 (63.3)	12 (60.0)	93 (63.7)	.464
Site, n (%) Frontal	105 (63.3)	15 (75.0)	90 (61.6)	.181
CNS WHO grade, n (%) 2 3	126 (75.9) 40 (24.1)	20 (100) 0 (0)	106 (72.6) 40 (27.4)	.003
Mitosis, n/10 HPFs Median (range)	1 (0–19)	0 (0–1)	1 (0–19)	0.070
Necrosis, n (%) Yes	11 (6.6)	0 (0)	11 (7.5)	0.232
Microvascular proliferation, n (%) Yes	40 (24.1)	2 (10.0)	38 (26.0)	0.092
Ki-67 %, n (%) Median (range)	5 (1–30)	2 (1–6)	6 (1–30)	0.001
IDH mutation, n (%) IDH1 codon 132 R132H R132G R132C IDH2 codon 172 R172K R172M R172S R172W	138 (83.1) 133 (80.1) 4 (2.4) 1 (0.6) 28 (16.9) 20 (12.0) 6 (3.7) 1 (0.6) 1 (0.6)	15 (75.0) 15 (75.0) 0 (0) 0 (0) 5 (25.0) 4 (20.0) 0 (0) 1 (5.0) 0 (0)	123 (84.2) 118 (80.8) 4 (2.7) 1 (0.7) 23 (15.8) 16 (10.9) 6 (4.2) 0 (0) 1 (0.7)	0.229^a
ATRX expression, n (%) Retained	166 (100)	20 (100)	146 (100)	-
TERTp mutation, n (%) C228T C250T Wildtype	105 (63.3) 41 (24.7) 24 (12.0)	- - 20 (100)	105 (71.9) 41 (28.1) -	-
CIC mutation, n (%) Yes Wildtype NA	45 (27.1) 27 (16.3) 94 (56.6)	12 (60.0) 8 (40.0) 0 (0)	33 (22.6) 19 (13.0) 94 (64.4)	.496
FUBP1 mutation, n (%) Yes Wildtype NA	11 (6.6) 62 (37.3) 93 (56.0)	1 (5.0) 19 (95.0) 0 (0)	10 (6.8) 43 (29.5) 93 (63.7)	.131
CDKN2A homozygous deletion, n (%) Yes	23 (13.9)	0 (0)	23 (15.8)	.041
DNA methylation-based score, n (%) ≥0.9 <0.9	140 (84.3) 26 (15.7)	6 (30.0) 14 (70.0)	134 (91.8) 12 (8.2)	<.001
MGMT, n (%) Methylated Unmethylated Undeterminable	156 (94.0) 2 (1.2) 8 (4.8)	13 (65.0) 0 (0) 7 (35.0)	143 (97.9) 2 (1.4) 1 (0.7)	-
CNV alterations, n (%) Isolated 1p/19q codeletion Additional CNV alterations	72 (43.4) 94 (56.6)	17 (85.0) 3 (15.0)	55 (37.7) 91 (62.3)	<.001
EOR, n (%) GTR STR Biopsy	72 (43.4) 69 (41.6) 25 (15.1)	7 (35.0) 12 (60.0) 1 (5.0)	65 (44.5) 57 (39.0) 24 (16.4)	.153
Adjuvant therapies, n (%) Radiotherapy/Chemotherapy	89 (53.6)	3 (15.0)	86 (58.9)	-
Disease progression, n (%) Yes No	88 (53.0) 78 (47.0)	1 (5.0) 19 (95.0)	87 (59.6) 79 (40.4)	-
Follow-up time, (months) Median (25th—75th percentiles)	72 (32 – 116)	87 (22.75 – 115.75)	71 (33 – 116)	-

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TERTp = TERT promoter, CNS = Central Nervous System, WHO = World Health Organization, HPFs = High-power fields, NA = not available, CNV = copy number variation, EOR = extent of resection, GTR = gross-total resection, STR = sub-total resection.

Statistically significant P-values are reported in bold.

^aThis analysis was performed considering IDH1 codon R132 and IDH2 codon R172 mutations as binary categorical variables.

Histological, Immunohistochemical, and Baseline Molecular Review

Of the 166 cases, 126 (75.9%) were classified as CNS WHO grade 2 tumors. The median mitotic activity was 1 mitosis per 10 HPFs (0.4 per mm²). Necrosis and microvascular proliferation were observed in 11 cases (6.6%) and 40 cases (24.1%), respectively. Immunohistochemistry revealed IDH1 R132H positivity in 138 cases (83.1%), with ATRX expression retained in 100% of cases. The median Ki-67 labeling index was 5% (range: 1%–30%). Molecular analysis from previously performed Sanger sequencing or NGS identified IDH2 codon 172 mutations in 28 patients (16.9%). CIC mutation status was available for 72 patients (43.4%), with pathogenic somatic variants detected in 45 (62.5%). FUBP1 molecular data were available for 73 patients (44.0%), of which 11 cases (15.1%) harbored a pathogenic variant.

Sequencing Analysis Identifies TERTp-Wildtype Status in the Vast Majority of Young Patients and WES Analysis Revealed Absence of Mutations in Telomere Maintenance-Related Genes of TERTp-Wildtype Cases

Sanger sequencing identified TERTp-wildtype status in 23 of 166 cases (13.8%). WES confirmed this status in 20 of these 23 cases (86.9%). In the remaining 3 cases (13.1%), WES detected canonical TERTp mutations (C228T in two cases and C250T in one case). Among the 20 confirmed TERTp-wildtype cases, 19 patients (95.0%) were ≤20 years old, and 1 patient (5.0%) was 27 years old (Figure 1A). No TERTp-wildtype case was detected in patients aged more than 30 years. Furthermore, IDH2 codon 172 mutation was identified in 5/20 (25.0%) TERT-p wildtype cases versus 23/146 (15.8%) in the TERTp-mutant group (Figure 1B). Within TERTp-mutant cases, the C228T mutation (71.9%) was approximately 2 times, and half more frequent than the C250T (28.1%). Chi-square analyses showed that age ≤39 years (P < .001), CNS WHO grade 2 (P = .003), and a Ki-67 proliferation index less or equal than 5% (median value) were significantly associated with TERTp-wildtype status (P = .001). The age distribution across the study cohort illustrated in Figure 1A and 1B.

Two bar charts compare characteristics of TERTp-wildtype and mutant cases. Panel A (left) shows horizontal bar chart with the distribution of TERTp-wildtype (blue, n=20) and TERTp-mutant (orange, n=146) cases across age groups. Panel B (right) displays vertical bar chart comparing the percentage of TERTp-wildtype and TERTp-mutant cases across four categories: “Age 14–20”, “IDH2 mutation”, “Additional CNVs beyond 1p/19q-codeletion”, and “DNA methylation-based score <0.9”. — Characterization of *TERT* promoter (*TERT*p) mutation in the study cohort. (A) Age distribution of *TERT*p-wildtype cases across decades. (B) Bar chart comparing the distribution of age (≤20 years), *IDH2* mutation, copy number variations and DNA methylation score between *TERT*p-wildtype and *TERT*p-mutant groups.

To explore the clonality of TERTp mutations, we selected two cases with markedly different Ki-67 expression levels. DNA was extracted from both areas using tissue punches, followed by TERTp Sanger sequencing, which revealed the presence of TERTp mutations in both regions (Supplementary Figure 2).

Similarly, to investigate whether TERTp mutations can be acquired during tumor progression, we analyzed recurrent TERTp-mutant cases with available primary tumor samples (n = 6; median PFS: 120 months [range: 32–234]). TERTp mutations were detected in all primary tumor samples of recurrent TERTp-mutant cases. Clinical and pathological features of the 6 analyzed patients are reported in Supplementary Table 2. In contrast, the single TERTp-wildtype case with tumor progression did not undergo surgical resection at recurrence, preventing the availability of recurrent tumor samples for similar analysis.

Comprehensive clinical, histopathological, and molecular data stratified by TERTp status are summarized in Table 1.

WES was performed on TERTp-wildtype cases identified through Sanger sequencing (n = 23) to assess TM-related gene mutations in TERTp-associated pathways. WES confirmed TERTp-wildtype status in 20 of these 23 cases, allowing a reassessment of TERTp status; however, no TM-related alterations were identified.

Epigenetic Profiling Reveals Distinct Clustering of TERTp-Wildtype and TERTp-Mutant Oligodendrogliomas

A focused t-distributed stochastic neighbor embedding (t-SNE) analysis was performed to assess the clustering patterns of oligodendrogliomas with different TERTp mutation statuses from the study cohort in relation to a reference cohort of 340 glial tumors from the Heidelberg Brain Tumour Classifier reference set (version v12.8).²⁶ The reference cohort included the following IDH-wildtype and IDH-mutant diffuse gliomas: glioblastoma, IDH-wildtype (n = 50); astrocytoma, IDH-mutant, lower grade (n = 50); astrocytoma, IDH-mutant, high grade (n = 50); diffuse hemispheric glioma, H3 G34-mutant (n = 30); diffuse midline glioma, H3 K27-altered (n = 30); diffuse leptomeningeal glioneuronal tumor (n = 40); diffuse pediatric-type high-grade glioma, H3 wildtype and IDH wildtype (n = 40); dysembryoplastic neuroepithelial tumor (n = 30); and oligosarcoma, IDH-mutant (n = 20).

The t-SNE analysis revealed that while TERTp-wildtype oligodendrogliomas exhibited the highest epigenetic resemblance to their mutant counterparts, they clustered together at the periphery of the TERTp-mutant group, representing an “epigenetic” extreme pole of oligodendrogliomas (Figure 2A). Further stratification by CIC mutation status, CNS WHO grade, and age at diagnosis revealed no significant distinctions between these subgroups or overlapping with the clusters based on TERTp status (Supplementary Figure 3A–C). These findings suggest that the distinct epigenetic profiles within oligodendroglioma are primarily associated with TERTp status among the assessed parameters (Figure 2B).

Two-panel scatter plot (t-SNE dimensionality reduction) showing DNA methylation-based clustering of brain tumor samples. Panel A shows clustering of the main glioma subtypes. Each dot represents a sample colored by tumor group. The pink group of TERTp-wildtype oligodendrogliomas forms a distinct cluster at the periphery of the purple TERTp-mutant cluster . Panel B presents a zoomed-in view of the oligodendroglioma subgroup only, with TERTp-mutant (purple) and TERTp-wildtype (pink) cases. — Unsupervised, nonlinear t-distributed stochastic neighbor embedding (t-SNE) of DNA methylation profiles from 450 glial tumor samples, being included from reference set of Heidelberg´s brain tumor classifier revealed that while *TERT*p-wildtype oligodendrogliomas showed the highest epigenetic resemblance to their mutant counterparts, they clustered together at the periphery of the *TERT*p-mutant group, representing an “epigenetic” extreme pole of oligodendrogliomas (A). Despite the epigenetic proximity between *TERT*p-wildtype and *TERT*p-mutant oligodendrogliomas, no overlap was observed in further t-SNE analyses considering the entire oligodendroglioma set (B).

Analysis of CNVs derived from the DNA methylation data showed whole-arm deletions of 1p and 19q in 166/166 (100%) of cases. These concurrent entity-defining alterations were alone in 72 (43.4%) cases, whereas additional single or multiple CNV alterations were observed in 94 (56.6%) cases. CDKN2A/B homozygous deletion was observed in 23/166 (15.8%) cases, all of them belonging to the TERTp-mutant subgroup. Interestingly, an association was found between the presence of isolated 1p/19q codeletion, with no additional CNV alteration, and TERTp-wildtype oligodendrogliomas (P < .001), as shown in Figure 1B. CNV plots (Figure 3) confirmed a trend of higher CNV alterations from TERTp-wildtype oligodendrogliomas in teenagers to their TERTp-mutant adult counterparts, as well as from CNS WHO 2 to grade 3 tumors (P = .024).

Three-panel bar plots (panels A–C) displaying genome-wide copy number alteration rates in different groups of oligodendroglioma, measured across chromosomes 1 to 22. Y-axis represents the alteration rate (%), with gains shown above the axis and losses below. X-axis represents chromosomal positions, with key genes labeled across each chromosome. Overall, the figure highlights increasing genomic instability from panel A to C, correlating with TERTp mutation status. — Cumulative copy number variations (CNV) plots of *TERT*p-wildtype cases (A), *TERT*p-mutant cases in young patients (≤30 years) (B), and *TERT*p-mutant cases in older patients (C). CNV profiles show a trend of increasing CNVs from *TERT*p-wildtype oligodendrogliomas in teenagers (A) to more alterations in the *TERT*p-mutant cases in adults (C). Annotations of the clinically relevant glioma-related gene loci have been added with descriptive purposes.

Methylation Analysis of Upstream and Proximal TERTp Regions

By analyzing data extracted from the available methylation arrays, we aimed to investigate whether the epigenetic regulation of TERTp in TERTp-wildtype oligodendrogliomas might be, contrary to the genetic alteration, in favor of TERT overexpression compared to their mutant counterparts. For this purpose, we compared the average of the extracted beta values for 5 CpGs within TERTp, covered by various arrays, between TERTp-wildtype and TERTp-mutant subgroups using 2-tailed unpaired t-tests. We observed a considerable DNA methylation heterogeneity between TERT upstream and proximal promoter regions. In line with prior reports,^33–35 showing that upstream hypermethylation and proximal hypomethylation of TERTp are associated with TERT overexpression, in our study the upstream and proximal promoter regions were remarkably hypermethylated and hypomethylated, respectively (0.70 vs. 0.09 methylation level; P-value <.0001). The analysis showed a lower level of methylation across 4 CpG sites within the upstream promoter region in TERTp-wildtype cases compared to TERTp-mutant (0.59 vs. 0.65 methylation level; P = .015), whereas there was no difference in the methylation level of the single CpG within the TERT proximal promoter region (Supplementary Table 3). Thus, the epigenetic regulation of TERTp in oligodendroglioma favors TERT expression less in TERTp-wildtype cases compared to their mutant counterparts.

Methylation Analysis of the HOXD12 Gene

To investigate whether methylation levels at cg23130254 in the HOXD12 gene differ according to TERTp status, we first performed a univariable linear regression of TERTp status on HOXD12, which revealed significantly lower methylation levels in TERTp-wildtype compared to TERTp-mutant (β = −0.111, 95% CI: −0.180 to −0.043). However, given that both age and CNS WHO grade were known to be independently associated with HOXD12 gene methylation,³⁰ as also confirmed in our sample (Supplementary Table 4) and were found to be associated with TERTp status (Table 1), we subsequently conducted a multivariable linear regression including these 2 covariates. In this adjusted model, the association between TERTp status and HOXD12 was no longer statistically significant (β = −0.033, 95% CI: −0.101 to 0.035), suggesting that the methylation difference may not be independently attributable to TERTp status, but may rather reflect underlying differences in age distribution or tumor biology between the groups.

PFS Analysis Indicated a Favorable Impact on PFS of TERTp-Wildtype Status in Oligodendroglioma

Follow-up data were available for all patients included in the cohort (n = 166). Median follow-up was 72.00 months across the whole cohort (25th and 75th percentiles: 32.00 and 116.00, respectively); 87.00 months in TERTp-wildtype patients (25th and 75th percentiles: 22.75 and 115.75, respectively); 71.00 months in TERTp-mutant patients (25th and 75th percentiles: 33.00 and 116.00, respectively). Tumor progression was observed in 88 (51.2%) cases, of which 87 (98.8%) in the TERTp-mutant group. Interestingly, within the TERTp-wildtype patient group, recurrence was exclusively observed in n = 1 patients over 20 years of age (27 years). The median PFS was 41.00 months (25th and 75th percentiles: 22.00 and 74.25, respectively) considering the whole cohort; 40.00 months in TERTp-mutant subgroup (25th and 75th percentiles: 22.75 and 71.00, respectively), and the PFS of the single TERTp-wildtype case with disease progression was 17 months.

TERTp-wildtype status (P = .003 [HR: 0.050 (95% CI: 0.007–0.362)]), age >39 years (P = .049 [HR: 1.531 (95% CI: 0.998–2.349)]), CNS WHO grade 3 (P < .001 [HR: 2.657 (95% CI: 1.701–4.151)]), mitotic count >1/10HPFs (P = .001 [HR: 2.242 (95% CI: 1.462–3.438)]), microvascular proliferation (P = .012 [HR: 1.785 (95% CI: 1.134–2.807)]), Ki-67 expression >5% (P = .006 [HR: 1.986 (95% CI: 1.218–3.238)]), and the presence of additional CNV alterations beyond 1p/19q codeletion (P = .001 [HR: 2.091 (95% CI: 1.327–3.294)]) emerged as statistically significant variables for PFS at univariate analysis, as shown in Table 2. The observed significant prognostic impact of TERTp-wildtype status on PFS was further confirmed by Cox regression multivariate analysis (P = .009 [HR: 0.068 (95% CI: 0.009–0.512)]). Full correlations between clinical, pathological, molecular variables and PFS at Cox regression models are detailed in Table 2.

Table 2:

Univariate and multivariate Cox regression analysis for PFS.

Variables	Univariate			Multivariate
	HR	95% CI	p-value	HR	95% CI	p-value
TERTp Mutant (reference) Wildtype	1 0.050	0.007-0.362	0.003	1 0.068	0.009-0.512	0.009
Age ≤39 y/o (reference) >39 y/o	1 1.531	0.998-2.349	0.049	1 1.043	0.674-1.614	0.849
Gender Male (reference) Female	1 1.173	0.754-1.826	0.479	_		_
Site Frontal (reference) Other	1 0.908	0.590-1.399	0.663	_		_
CNS WHO grade 2 (reference) 3	1 2.657	1.701-4.151	<0.001	1 2.368	0.929-6.036	0.071
Mitosis^a ≤1/10 HPFs (reference) >1/10 HPFs	1 2.242	1.462-3.438	<0.001	1 1.025	0.476-2.210	0.949
Necrosis Absent (reference) Present	1 1.857	0.919-3.756	0.085	_		_
Microvascular proliferation Absent (reference) Present	1 1.785	1.134-2.807	0.012	1 0.831	0.377-1.833	0.646
Ki-67^a ≤5% (reference) >5%	1 1.986	1.218-3.238	0.006	1 0.887	0.494-1.591	0.687
CNV alterations Isolated 1p/19q codeletion (reference) Additional CNV alterations	1 2.091	1.327-3.294	0.001	1 1.381	0.851-2.240	0.191
CDKN2A/B homozygous deletion Absent (reference) Present	1 1.616	0.922-2.834	0.094	_		_
IDH mutations IDH1 R132 (reference) IDH2 R172	1 0.902	0.509-1.601	0.725	_		_
CIC mutation^b Absent (reference) Present	1 0.912	0.473-1.757	0.782	_		_
FUBP1 mutation^c Absent (reference) Present	1 0.508	0.248-1.043	0.065	_		_
HOXD12 methylation^e Absent (reference) Present	1 1.228	0.989-1.525	0.063	_		_
EOR Biopsy/STR (reference) GTR	1 0.664	0.426-1.035	0.071	_		_
Adjuvant treatment Yes (reference) No	1 1.442	0.935-2.225	0.098	_		_

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TERTp = TERT promoter, PFS = progression-free survival, CNS = Central Nervous System, WHO = World Health Organization, HPFs = High-power fields, CNV = Copy Number Variation, EOR = extent of resection, GTR = gross-total resection, STR = sub-total resection.

^aConsidered as categorical binary variables, according to the median value.

^bCalculated on 72 cases (based on data availability).

^cCalculated on 73 cases (based on data availability). ^dCalculated on 158 cases (based on data availability).

^eBased on beta values of HOXD12 gene CpG site cg23130254. Multivariate analysis was performed on variables that reached significance on univariate analysis. Statistically significant p-values are reported in bold.

KM analysis (Figure 4A–D), conducted to explore the prognostic significance of TERTp-wildtype status throughout the whole cohort as well as within distinct patient subgroups, revealed a statistically significant favorable impact on PFS for TERTp-wildtype status versus TERTp-mutant across the whole cohort (P < .001 [HR 0.053 (0.030–0.091)]) as well as within patients ≤39 years (P < .001 [HR: 0.052 (95% CI: 0.026–0.103)]), within CNS WHO grade 2 tumors (P < .001 [HR: 0.066 (95% CI: 0.035–0.126)]) and according to different extents of resection (P < .001).

Four Kaplan–Meier curves (panels A–D) showing progression-free survival (PFS) probability over time, in years, for oligodendroglioma patients stratified by TERTp mutation status and clinical subgroups. The y-axis shows PFS probability (%), and the x-axis shows time in years. Panel A: TERTp-wildtype (green) vs. TERTp-mutant (red). Wildtype cases show significantly prolonged PFS compared to mutants. Panel B: Subgroup of patients aged ≤39 years. TERTp-wildtype (green) again shows markedly improved PFS compared to TERTp-mutant (purple). Panel C: WHO Grade 2 tumors. TERTp-wildtype (green) cases have superior PFS relative to TERTp-mutant (blue). Panel D: Stratified by extent of surgical resection: gross total resection (GTR) vs. subtotal resection (STR). TERTp-wildtype GTR (green) group shows best PFS, while TERTp-mutant STR (purple) shows the worst. — Kaplan–Meier curves by log-rank test. *TERT*p-wildtype status was significantly associated with better progression-free survival (PFS) in the overall cohort (A), and this association remained significant in specific patient subgroups such as in patients aged ≤39 years (B), in CNS WHO grade 2 tumors (C) and by subgrouping patients based on different extent of resection (D).

The methylation status of a previously identified prognostically relevant CpG site within HOXD12 did not correlate with PFS in a Cox proportional hazards regression analysis, either across the entire cohort (P = 0.063 [HR 1.228 (0.989–1.525)]), within the younger cohort (≤39 years; P = .053 [HR 2.048 (1.024–4.097)]), or within the subgroup of CNS WHO grade 2 patients (P = .345 [HR 1.298 (0.755–2.233)]).

Discussion

Herein, we described a peculiar subset of IDH-mutant and 1p/19q-codeleted oligodendroglioma patients lacking TERTp mutation, showing considerably favorable PFS and distinct molecular characteristics.

A major finding of this study relates to the high frequency (95.0%) of TERTp-wildtype status in tumors arising in young patients (≤20 years). The reported frequency of TERTp mutation ranges from 70%³⁶ to 96%,^14,15 most likely due to revisions in the definition of oligodendroglioma, shifting from a histological entity to one defined by IDH mutation and 1p/19q codeletion as essential molecular diagnostic criteria. The most recent studies consistently report a TERTp mutation rate exceeding 90% in IDH-mutant and 1p/19q-codeleted cases,^16,25 regardless of patient age. To the best of our knowledge, this study presents the largest cohort of TERTp-wildtype cases in IDH-mutant and 1p/19q-codeleted oligodendroglioma, expanding on previous findings (n = 3) that highlighted a strong link between TERTp-wildtype status and the teenage years.¹⁸

A key finding of our study is the prognostic impact of TERTp status in oligodendroglioma patients. TERTp-wildtype patients showed significantly better PFS in both KM and multivariate regression analyses, stratified by age, CNS WHO grade, and extent of resection. While IDH mutations, combined with 1p/19q codeletions, are well known to define oligodendroglioma as a glial tumor with significantly better clinical outcomes compared to both IDH-wildtype glioblastoma and IDH-mutant astrocytoma,³⁷ our findings indicate that TERTp status adds an additional layer of prognostic stratification in oligodendrogliomas, allowing to identify a subgroup of tumors with a relevantly better outcome than CNS WHO grade 2 TERTp-mutant oligodendrogliomas. Our findings expand the concept of molecular grading in adult-type diffuse gliomas and, for the first time in oligodendrogliomas, suggest the relevance of a molecular marker to identify a lower-risk subgroup of patients. Therefore, “oligodendroglioma, IDH-mutant, 1p/19q-codeleted, and TERTp-wildtype” could represent a CNS WHO grade 1 oligodendroglioma associated with young age, as well as CDKN2A/B deletion has recently drawn attention as a potential marker able to identify the malignant counterpart of the oligodendroglioma spectrum.³⁸ However, the clinical significance of CDKN2A/B alterations in oligodendroglioma still remains debated.³⁹ The prognostic impact of TERTp-wildtype status represents a compelling novel finding, as the extremely limited number of TERTp-wildtype cases in prior oligodendroglioma cohorts^14,24,25 has made it impracticable to statistically evaluate the impact of TERTp status on PFS. In a recent study⁴⁰ aiming at analyzing long-term outcomes in patients with CNS WHO grade 2 oligodendroglioma, the median PFS was 6.8 years, and the 5-year PFS rate was 60%. In our cohort, TERTp-wildtype patients showed a 5-year PFS rate of 93.7% versus 52.1% of TERTp-mutant. Taking into account patients with CNS WHO grade 2 only (n = 126), TERTp-wildtype patients showed a 5-year PFS rate of 93.7% versus 61.1% of TERTp-mutant. Notably, TERTp-wildtype cases undergoing STR showed a better prognosis compared to TERTp-mutant cases with surgical GTR. Moreover, it would have been interesting to confirm the significantly superior outcome of TERTp-wildtype oligodendrogliomas also in terms of overall survival (OS), and the lack of this endpoint could represent a limitation of our study. However, median OS in oligodendrogliomas is a too-prolonged measure to be investigated under acceptable conditions, as even shown by the most valued clinical trials.⁴¹

Our findings hold clinical relevance in light of recent results from the INDIGO study,⁴¹ a phase 3 trial of vorasidenib, an IDH1/IDH2 inhibitor, which improved PFS and delayed intervention in patients with CNS WHO grade 2 IDH-mutant gliomas. The study focused on “low-risk” patients in the earliest phase of IDH-mutant glioma, typically managed with a “watch and wait” approach. Gatto et al.⁴² identified an “intermediate risk” subgroup within this population that could benefit most from vorasidenib patients with stable, slow-growing tumors who do not need immediate adjuvant therapy.

Our findings on the role of TERTp status in refining risk stratification in CNS WHO grade 2 oligodendrogliomas may provide a more reproducible approach within the low-risk subgroup, helping identify the best candidates for “watch and wait” versus “vorasidenib treatment.”

We further explored whether the TERTp-wildtype subgroup represents “early” or “distinct” oligodendrogliomas, as the timeline of driver genetic events in gliomagenesis remains debated.^43–45 To explore this, we collected samples from regions with markedly different Ki-67 expression within the same paraffin block and performed TERTp sequencing on both high and low Ki-67 areas. TERTp was found to be equally mutant in both areas, suggesting that TERTp status in oligodendrogliomas is independent of the sampled region. However, investigations on a larger number of cases are mandatory to give consistency to the trend we observed on just 2 cases. To further explore whether TERTp mutation might be acquired over time during tumorigenesis, we analyzed 6 TERTp-mutant recurrent cases with available primary tumor samples. TERTp sequencing showed the mutation was present in both primary and recurrent samples in all 6 cases. These findings align with a recent study that investigated TERTp mutation clonality through whole-tumor analysis, showing that TERTp mutation, along with IDH mutation,⁴⁵ is among the earliest events in glioma development and evolution.⁷ The considerably long PFS of the 6 investigated cases supports even more the stability of TERTp mutation.

In terms of the epigenetic profile, TERTp-wildtype oligodendrogliomas closely resembled their mutant counterparts, but shaped a distinct cluster at the periphery of TERTp-mutant oligodendrogliomas. While IDH-mutant and 1p/19q-codeleted oligodendroglioma achieved the highest score in Heidelberg’s brain tumor classifier v12.8, the vast majority of TERTp-wildtype cases had scores below the 0.9 cutoff, indicating a slightly different epigenetic profile, which was further confirmed by t-SNE analysis. CNV analysis revealed a trend of increased alterations from TERTp-wildtype oligodendrogliomas in teenagers to their TERTp-mutant adult counterparts.

To investigate whether TERT overexpression in TERTp-wildtype oligodendrogliomas might be epigenetically regulated, we analyzed the methylation status of CpGs within TERTp, including key upstream (cg11625005) and proximal promoter sites (cg10896616). Previous studies have shown that upstream hypermethylation and proximal hypomethylation of TERTp lead to TERT overexpression in various cancer cell lines and tissues.^33–35 Based on this, our findings suggest that TERT overexpression due to TERTp mutation is not epigenetically compensated in TERTp-wildtype oligodendrogliomas, potentially further explaining the favorable clinical outcomes in these patients. However, further validation at the protein expression level may be needed since the impact of allele-specific DNA methylation within the TERTp on gene transcription still remains controversial.⁴⁶

Given that genetic and epigenetic regulations do not favor TERT overexpression in TERTp-wildtype oligodendrogliomas as they do in their mutant counterparts, we performed WES analysis to explore alternative mechanisms of replicative senescence evasion. However, TERTp-wildtype cases did not reveal any meaningful mutations in TM-related genes. Although TM has been considered a key event in glioma development,⁴ it may not be mandatory in IDH-mutant and 1p/19q-codeleted oligodendrogliomas in young patients.

TERTp mutation analysis is virtually limited to DNA-based methods, sequencing, and pyrosequencing in particular. Due to the high cytosine-guanosine content in the TERTp sequence, both the analysis through Sanger and NGS-based methods can be challenging.^23,47 The testing through Sanger sequencing was conducted by using genomic DNA and a specific pair of primers to cover the whole promoter region and identify all mutation variants. To further assess TERTp status and minimize the error margin of the analysis, cases without sequence variations on Sanger sequencing (n = 23) were tested with WES, and the wildtype status was confirmed in in 20/23 (86.9%) cases, supporting the importance of a multi-method approach to explore TERTp status. Unfortunately, no reliable immunohistochemical marker can be used in routine practice as an indirect indication of the presence or absence of TERTp mutations.⁴⁸

We further investigated HOXD12 methylation status, recently shown to correlate significantly with age and prognosis in oligodendrogliomas.³⁰ Our findings showed higher levels of HOXD12 methylation in TERTp-mutant patients compared to TERTp-wildtype. However, multivariable linear regression analysis suggested that the association between TERTp status and HOXD12 methylation, observed by univariable analysis, may be confounded by age and WHO grade. Notably, 2 other CpG sites previously reported to have prognostic significance were not consistently included across the various arrays used in the present study (450k, 850k, and EPICv2.0), and were therefore not analyzed.

In summary, TERTp-wildtype oligodendrogliomas represent a distinct subgroup of IDH-mutant, 1p/19q-codeleted gliomas, characterized by unique genetic and epigenetic features, as well as distinct age distribution and clinical course. Incorporating this finding into risk stratification may improve the standard of care for these patients.

Supplementary material

Supplementary material is available online at Neuro-Oncology (https://academic.oup.com/neuro-oncology).

noaf141_Supplementary_Tables_1-4

noaf141_supplementary_tables_1-4.docx^{(36.4KB, docx)}

noaf141_Supplementary_Figures_1-3

noaf141_supplementary_figures_1-3.docx^{(14.1KB, docx)}

Acknowledgments

The authors would like to acknowledge Vanessa Kelbch and Joshua Trautner for their invaluable assistance with the molecular analyses and Aurel Perren for the precious contribution of his Institution to this study.

Contributor Information

Filippo Nozzoli, Histopathology and Molecular Diagnostics, Careggi University Hospital, Florence, Italy; Section of Anatomic Pathology, Department of Health Sciences, University of Florence, Florence, Italy.

Ramin Rahmanzade, Clinical Cooperation Unit Neuropathology, German Consortium for Translational Cancer Research (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany; Department of Neuropathology, Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany; Institute of Pathology, Ludwig Maximilians University Hospital Munich, Munich, Germany.

Simone Schmid, German Cancer Consortium (DKTK), Partner Site Berlin, and German Cancer Research Center (DKFZ), Heidelberg, Germany; Department of Neuropathology, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt—Universität zu Berlin, Berlin, Germany.

Leonille Schweizer, German Cancer Consortium (DKTK), Partner Site Frankfurt/Mainz, German Cancer Research Center (DKFZ), Heidelberg, Germany; Frankfurt Cancer Institute (FCI), Frankfurt am Main, Germany; Institute of Neurology (Edinger Institute), University Hospital Frankfurt, Goethe University, Frankfurt am Main, Germany.

Daniel Schrimpf, Department of Neuropathology, Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany.

Dennis Friedel, Department of Neuropathology, Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany.

Kirsten Göbel, Department of Neuropathology, Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany.

David E Reuss, Clinical Cooperation Unit Neuropathology, German Consortium for Translational Cancer Research (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany; Department of Neuropathology, Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany.

Rouzbeh Banan, Clinical Cooperation Unit Neuropathology, German Consortium for Translational Cancer Research (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany; Department of Neuropathology, Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany.

Philipp Sievers, Clinical Cooperation Unit Neuropathology, German Consortium for Translational Cancer Research (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany; Department of Neuropathology, Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany.

Stefan Pusch, Clinical Cooperation Unit Neuropathology, German Consortium for Translational Cancer Research (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany; Department of Neuropathology, Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany.

Henri Bogumil, Clinical Cooperation Unit Neuropathology, German Consortium for Translational Cancer Research (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany; Department of Neuropathology, Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany.

Felix Hinz, Clinical Cooperation Unit Neuropathology, German Consortium for Translational Cancer Research (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany; Department of Neuropathology, Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany.

Abigail K Suwala, Clinical Cooperation Unit Neuropathology, German Consortium for Translational Cancer Research (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany; Department of Neuropathology, Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany.

Fuat Kaan Aras, Clinical Cooperation Unit Neuropathology, German Consortium for Translational Cancer Research (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany; Department of Neuropathology, Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany.

Lukas Friedrich, Clinical Cooperation Unit Neuropathology, German Consortium for Translational Cancer Research (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany; Department of Neuropathology, Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany.

Simona Osella-Abate, Pathology Unit, Città della Salute e della Scienza University Hospital, Turin, Italy.

Alessia Andrea Ricci, Pathology Unit, Department of Medical Sciences, University of Turin, Turin, Italy.

Alessandra Macciotta, Department of Medical Sciences, University of Turin and CPO Piemonte, Turin, Italy.

Thorsten Simon, Department of Pediatric Oncology and Hematology, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany.

Gudrun Fleischhack, Pediatric Hematology and Oncology, Pediatrics III, University Children’s Hospital of Essen, Essen, Germany.

Kathy Keyvani, Institute of Neuropathology, University of Duisburg-Essen, Essen, Germany.

Jordan R Hansford, South Australia Immunogenomics Cancer Institute, University of Adelaide, Adelaide, South Australia, Australia; South Australia Health and Medical Research Institute, Adelaide, South Australia, Australia; Michael Rice Centre for Hematology and Oncology, Women’s and Children’s Hospital, Adelaide, South Australia, Australia.

Dong-Anh Khuong-Quang, Children’s Cancer Centre, Royal Children’s Hospital Melbourne, Melbourne, Victoria, Australia; Department of Pediatrics, Murdoch Children’s Research Institute, University of Melbourne, Melbourne, Victoria, Australia.

Philippe Schucht, Department of Neurosurgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.

Theoni Maragkou, Institute of Tissue Medicine and Pathology, University of Bern, Bern, Switzerland.

Tareq A Juratli, Department of Neurosurgery, Division of Neuro-Oncology, Faculty of Medicine, Carl Gustav Carus University Hospital, TU Dresden, Dresden, Germany.

Matthias Meinhardt, Department of Pathology, Faculty of Medicine and Carl Gustav Carus University Hospital, TU Dresden, Dresden, Germany.

Sabrina Zechel, Department of Neuropathology, University Medical Center Göttingen, Göttingen, Germany.

Christine Stadelmann, Department of Neuropathology, University Medical Center Göttingen, Göttingen, Germany.

Roland Coras, Department of Neuropathology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.

Oliver W Sakowitz, Institute of Pathology and Neuropathology, RKH Klinikum Ludwigsburg, Ludwigsburg, Germany.

Benjamin Goeppert, Institute of Pathology and Neuropathology, RKH Klinikum Ludwigsburg, Ludwigsburg, Germany; Institute of Tissue Medicine and Pathology, University of Bern, Bern, Switzerland.

Jens Schittenhelm, Department of Neuropathology, Institute of Pathology and Neuropathology, University Hospital of Tübingen, Tübingen, Germany.

Nima Etminan, Department of Neurosurgery, University Hospital Mannheim, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany.

Miriam Ratliff, Department of Neurosurgery, University Hospital Mannheim, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany.

Christel Herold-Mende, Division of Experimental Neurosurgery, Department of Neurosurgery, Heidelberg University Hospital, Heidelberg, Germany.

Stefan M Pfister, Division of Pediatric Neuro-Oncology (B062), German Cancer Research Center (DKFZ) and German Cancer Consortium (DKTK), Heidelberg, Germany; National Center for Tumor Diseases (NCT), Heidelberg, Germany; Department of Pediatric Hematology and Oncology, Heidelberg University Hospital, Heidelberg, Germany; Hopp Children’s Cancer Center (KiTZ), Heidelberg, Germany.

Wolfgang Wick, Department of Neurology and Neurooncology Program, National Center for Tumor Diseases, Heidelberg University Hospital, Heidelberg, Germany; Clinical Cooperation Unit Neurooncology, German Cancer Research Center (DKFZ), Heidelberg, Germany.

Sandro M Krieg, Department of Neurosurgery, Heidelberg University Hospital, Heidelberg, Germany.

Andreas von Deimling, Clinical Cooperation Unit Neuropathology, German Consortium for Translational Cancer Research (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany; Department of Neuropathology, Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany.

Felix Sahm, CCU Neuropathology, German Consortium for Translational Cancer Research (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany; Clinical Cooperation Unit Neuropathology, German Consortium for Translational Cancer Research (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany; Department of Neuropathology, Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany.

Luca Bertero, Pathology Unit, Department of Medical Sciences, University of Turin, Turin, Italy; Pathology Unit, Città della Salute e della Scienza University Hospital, Turin, Italy.

Conflict of interest statement

R.R. is a fellow of the AI Health Innovation Cluster Clinician Scientist Program. A.v.D. and F.S. are co-founders of Heidelberg Epignostix GmbH. The other authors declare no conflict of interest.

Author Contributions

F.S. and L.B. conceived, designed, and supervised the study. S.O.A., A.A.R., and A.M. curated the formal analysis. F.N., R.R., A.v.D., D.E.R., R.B., P.S., H.B., A.K.S., F.H., and F.K.A. offered pathological review. F.N., R.R., D.S., D.F., K.G., L.F., and S.P. curated molecular analysis. T.S., G.F., J.R.H., D.A.K., P.S., T.M., T.J., O.W.S., C.H.M., S.M.P., W.W., and S.M.K. provided clinical data. S.S., L.S., K.K., M.M., S.Z., C.S.N., R.C., J.S., B.G., N.E., and M.R. provided tissue specimens and offered pathological review. F.N. and R.R. wrote the manuscript and all authors reviewed and approved the manuscript for publication.

Ethics Statement

Collection and analysis of tissue samples and clinical data were performed in accordance with the principles of the Declaration of Helsinki.

Data Availability

Data will be made available upon reasonable request.

References

1. WHO Classification of Tumours Editorial Board. Central Nervous System Tumours. Lyon: International Agency for Research on Cancer; 2021. (WHO Classification of Tumours Series, 5th ed., Vol. 6). https://publications.iarc.fr/601 [Google Scholar]
2. Cahill DP, Louis DN, Cairncross JG.. Molecular background of oligodendroglioma: 1p/19q, IDH, TERT, CIC and FUBP1. CNS Oncol. 2015;4(5):287–294. [DOI] [PMC free article] [PubMed] [Google Scholar]
3. Kim S, Chowdhury T, Yu HJ, et al. The telomere maintenance mechanism spectrum and its dynamics in gliomas. Genome Med. 2022;14(1):88. [DOI] [PMC free article] [PubMed] [Google Scholar]
4. Walsh KM, Wiencke JK, Lachance DH, et al. Telomere maintenance and the etiology of adult glioma. Neuro Oncol. 2015;17(11):1445–1452. [DOI] [PMC free article] [PubMed] [Google Scholar]
5. Ackermann S, Fischer M.. Telomere maintenance in pediatric cancer. Int J Mol Sci . 2019;20(23):5836. [DOI] [PMC free article] [PubMed] [Google Scholar]
6. Killela PJ, Reitman ZJ, Jiao Y, et al. TERT promoter mutations occur frequently in gliomas and a subset of tumors derived from cells with low rates of self-renewal. Proc Natl Acad Sci U S A. 2013;110(15):6021–6026. [DOI] [PMC free article] [PubMed] [Google Scholar]
7. Appin CL, Hong C, Suwala AK, et al. Whole tumor analysis reveals early origin of the TERT promoter mutation and intercellular heterogeneity in TERT expression. Neuro Oncol. 2024;26(4):640–652. [DOI] [PMC free article] [PubMed] [Google Scholar]
8. Waitkus MS, Erman EN, Reitman ZJ, Ashley DM.. Mechanisms of telomere maintenance and associated therapeutic vulnerabilities in malignant gliomas. Neuro Oncol. 2024;26(6):1012–1024. [DOI] [PMC free article] [PubMed] [Google Scholar]
9. Liu XY, Gerges N, Korshunov A, et al. Frequent ATRX mutations and loss of expression in adult diffuse astrocytic tumors carrying IDH1/IDH2 and TP53 mutations. Acta Neuropathol. 2012;124(5):615–625. [DOI] [PubMed] [Google Scholar]
10. Reuss DE, Sahm F, Schrimpf D, et al. ATRX and IDH1-R132H immunohistochemistry with subsequent copy number analysis and IDH sequencing as a basis for an “integrated” diagnostic approach for adult astrocytoma, oligodendroglioma and glioblastoma. Acta Neuropathol. 2015;129(1):133–146. [DOI] [PubMed] [Google Scholar]
11. Akyerli CB, Yüksel S, Can O, et al. Use of telomerase promoter mutations to mark specific molecular subsets with reciprocal clinical behavior in IDH mutant and IDH wild-type diffuse gliomas. J Neurosurg. 2018;128(4):1102–1114. [DOI] [PubMed] [Google Scholar]
12. Arita H, Ichimura K.. Prognostic significance of TERT promoter mutations in adult-type diffuse gliomas. Brain Tumor Pathol. 2022;39(3):121–129. [DOI] [PubMed] [Google Scholar]
13. Lee K, Kim SI, Kim EE, et al. Genomic profiles of IDH-mutant gliomas: MYCN-amplified IDH-mutant astrocytoma had the worst prognosis. Sci Rep. 2023;13(1):6761. [DOI] [PMC free article] [PubMed] [Google Scholar]
14. Lee Y, Koh J, Kim SI, et al. The frequency and prognostic effect of TERT promoter mutation in diffuse gliomas. Acta Neuropathol Commun. 2017;5(1):62. [DOI] [PMC free article] [PubMed] [Google Scholar]
15. Pekmezci M, Rice T, Molinaro AM, et al. Adult infiltrating gliomas with WHO 2016 integrated diagnosis: additional prognostic roles of ATRX and TERT. Acta Neuropathol. 2017;133(6):1001–1016. [DOI] [PMC free article] [PubMed] [Google Scholar]
16. Shi ZF, Li KK, Chan DT, Mao Y, Ng H-K.. Alternative lengthening of telomeres is seen in a proportion of oligodendrogliomas and is associated with a worse prognosis. Neurooncol. Adv.. 2024;6(1):vdae006. [DOI] [PMC free article] [PubMed] [Google Scholar]
17. Aihara K, Mukasa A, Nagae G, et al. Genetic and epigenetic stability of oligodendrogliomas at recurrence. Acta Neuropathol Commun. 2017;5(1):18. [DOI] [PMC free article] [PubMed] [Google Scholar]
18. Lee J, Putnam AR, Chesier SH, et al. Oligodendrogliomas, IDH-mutant and 1p/19q-codeleted, arising during teenage years often lack TERT promoter mutation that is typical of their adult counterparts. Acta Neuropathol Commun. 2018;6(1):95. [DOI] [PMC free article] [PubMed] [Google Scholar]
19. Ceccarelli M, Barthel FP, Malta TM, et al. ; TCGA Research Network. Molecular profiling reveals biologically discrete subsets and pathways of progression in diffuse glioma. Cell. 2016;164(3):550–563. [DOI] [PMC free article] [PubMed] [Google Scholar]
20. Qaddoumi I, Orisme W, Wen J, et al. Genetic alterations in uncommon low-grade neuroepithelial tumors: BRAF, FGFR1, and MYB mutations occur at high frequency and align with morphology. Acta Neuropathol. 2016;131(6):833–845. [DOI] [PMC free article] [PubMed] [Google Scholar]
21. Ramkissoon LA, Horowitz PM, Craig JM, et al. Genomic analysis of diffuse pediatric low-grade gliomas identifies recurrent oncogenic truncating rearrangements in the transcription factor MYBL1. Proc Natl Acad Sci U S A. 2013;110(20):8188–8193. [DOI] [PMC free article] [PubMed] [Google Scholar]
22. Rodriguez FJ, Tihan T, Lin D, et al. Clinicopathologic features of pediatric oligodendrogliomas: a series of 50 patients. Am J Surg Pathol. 2014;38(8):1058–1070. [DOI] [PMC free article] [PubMed] [Google Scholar]
23. Dubbink HJ, Atmodimedjo PN, Kros JM, et al. Molecular classification of anaplastic oligodendroglioma using next-generation sequencing: a report of the prospective randomized EORTC Brain Tumor Group 26951 phase III trial. Neuro Oncol. 2016;18(3):388–400. [DOI] [PMC free article] [PubMed] [Google Scholar]
24. Arita H, Matsushita Y, Machida R, et al. TERT promoter mutation confers favorable prognosis regardless of 1p/19q status in adult diffuse gliomas with IDH1/2 mutations. Acta Neuropathol Commun. 2020;8(1):201. [DOI] [PMC free article] [PubMed] [Google Scholar]
25. Lee Y, Park CK, Park SH.. Prognostic impact of TERT promoter mutations in adult-type diffuse gliomas based on WHO2021 criteria. Cancers (Basel). 2024;16(11):2032. [DOI] [PMC free article] [PubMed] [Google Scholar]
26. Capper D, Jones DTW, Sill M, et al. DNA methylation-based classification of central nervous system tumours. Nature. 2018;555(7697):469–474. [DOI] [PMC free article] [PubMed] [Google Scholar]
27. Rahmanzade R, Pfaff E, Banan R, et al. Genetical and epigenetical profiling identifies two subgroups of pineal parenchymal tumors of intermediate differentiation (PPTID) with distinct molecular, histological and clinical characteristics. Acta Neuropathol. 2023;146(6):853–856. [DOI] [PMC free article] [PubMed] [Google Scholar]
28. Capper D, Stichel D, Sahm F, et al. Practical implementation of DNA methylation and copy-number-based CNS tumor diagnostics: the Heidelberg experience. Acta Neuropathol. 2018;136(2):181–210. [DOI] [PMC free article] [PubMed] [Google Scholar]
29. Shirahata M, Ono T, Stichel D, et al. Novel, improved grading system(s) for IDH-mutant astrocytic gliomas. Acta Neuropathol. 2018;136(1):153–166. [DOI] [PubMed] [Google Scholar]
30. Nuechterlein N, Cimino S, Shelbourn A, et al. HOXD12 defines an age-related aggressive subtype of oligodendroglioma. Acta Neuropathol. 2024;148(1):41. [DOI] [PMC free article] [PubMed] [Google Scholar]
31. Braun DM, Chung I, Kepper N, Deeg KI, Rippe K.. TelNet - a database for human and yeast genes involved in telomere maintenance. BMC Genet. 2018;19(1):32. [DOI] [PMC free article] [PubMed] [Google Scholar]
32. Wen PY, van den Bent M, Youssef G, et al. RANO 2.0: update to the response assessment in neuro-oncology criteria for high- and low-grade gliomas in adults. J Clin Oncol. 2023;41(33):5187–5199. [DOI] [PMC free article] [PubMed] [Google Scholar]
33. Castelo-Branco P, Choufani S, Mack S, et al. Methylation of the TERT promoter and risk stratification of childhood brain tumours: an integrative genomic and molecular study. Lancet Oncol. 2013;14(6):534–542. [DOI] [PubMed] [Google Scholar]
34. Kouroukli AG, Fischer A, Kretzmer H, et al. The DNA methylation status of the TERT promoter differs between subtypes of mature B-cell lymphomas. Blood Cancer J. 2023;13(1):98. [DOI] [PMC free article] [PubMed] [Google Scholar]
35. Rowland TJ, Bonham AJ, Cech TR.. Allele-specific proximal promoter hypomethylation of the telomerase reverse transcriptase gene (TERT) associates with TERT expression in multiple cancers. Mol Oncol. 2020;14(10):2358–2374. [DOI] [PMC free article] [PubMed] [Google Scholar]
36. Heidenreich B, Rachakonda PS, Hosen I, et al. TERT promoter mutations and telomere length in adult malignant gliomas and recurrences. Oncotarget. 2015;6(12):10617–10633. [DOI] [PMC free article] [PubMed] [Google Scholar]
37. Brat DJ, Verhaak RG, Aldape KD, et al. ; Cancer Genome Atlas Research Network. Comprehensive, integrative genomic analysis of diffuse lower-grade gliomas. N Engl J Med. 2015;372(26):2481–2498. [DOI] [PMC free article] [PubMed] [Google Scholar]
38. Otsuji R, Hata N, Yamamoto H, et al. Hemizygous deletion of cyclin-dependent kinase inhibitor 2A/B with p16 immuno-negative and methylthioadenosine phosphorylase retention predicts poor prognosis in IDH-mutant adult glioma. Neurooncol Adv. 2024;6(1):vdae069. [DOI] [PMC free article] [PubMed] [Google Scholar]
39. Ippen FM, Hielscher T, Friedel D, et al. The prognostic impact of CDKN2A/B hemizygous deletions in IDH-mutant glioma. Neuro Oncol. 2024;27(3):743–754. [DOI] [PMC free article] [PubMed] [Google Scholar]
40. Byeon Y, Lee C, Jeon J, et al. Long-term outcomes of CNS WHO grade 2 oligodendroglioma in adult patients: a single-institution experience. Discov Oncol. 2024;15(1):268. [DOI] [PMC free article] [PubMed] [Google Scholar]
41. Mellinghoff IK, van den Bent MJ, Blumenthal DT, et al. ; INDIGO Trial Investigators. Vorasidenib in IDH1- or IDH2-mutant low-grade glioma. N Engl J Med. 2023;389(7):589–601. [DOI] [PMC free article] [PubMed] [Google Scholar]
42. Gatto L, Di Nunno V, Tosoni A, et al. Vorasidenib in IDH1/2-mutant low-grade glioma: the grey zone of patient’s selection. Front Oncol. 2024;13:1339266. [DOI] [PMC free article] [PubMed] [Google Scholar]
43. Exner ND, Valenzuela JAC, Abou-El-Ardat K, et al. Deep sequencing of a recurrent oligodendroglioma and the derived xenografts reveals new insights into the evolution of human oligodendroglioma and candidate driver genes. Oncotarget. 2019;10(38):3641–3653. [DOI] [PMC free article] [PubMed] [Google Scholar]
44. Suzuki H, Aoki K, Chiba K, et al. Mutational landscape and clonal architecture in grade II and III gliomas. Nat Genet. 2015;47(5):458–468. [DOI] [PubMed] [Google Scholar]
45. Watanabe T, Nobusawa S, Kleihues P, Ohgaki H.. IDH1 mutations are early events in the development of astrocytomas and oligodendrogliomas. Am J Pathol. 2009;174(4):1149–1153. [DOI] [PMC free article] [PubMed] [Google Scholar]
46. Lee DD, Komosa M, Sudhaman S, et al. Dual role of allele-specific DNA hypermethylation within the TERT promoter in cancer. J Clin Invest. 2021;131(21):e146915. [DOI] [PMC free article] [PubMed] [Google Scholar]
47. Zacher A, Kaulich K, Stepanow S, et al. Molecular diagnostics of gliomas using next generation sequencing of a glioma-tailored gene panel. Brain Pathol. 2017;27(2):146–159. [DOI] [PMC free article] [PubMed] [Google Scholar]
48. Dono A, Moosvi AM, Goli PS, et al. TERT immunohistochemistry as a surrogate marker for TERT promoter mutations in infiltrating gliomas. Appl Immunohistochem Mol Morphol. 2023;31(5):288–294. [DOI] [PMC free article] [PubMed] [Google Scholar]

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

noaf141_Supplementary_Tables_1-4

noaf141_supplementary_tables_1-4.docx^{(36.4KB, docx)}

noaf141_Supplementary_Figures_1-3

noaf141_supplementary_figures_1-3.docx^{(14.1KB, docx)}

Data Availability Statement

Data will be made available upon reasonable request.

[CIT0001] 1. WHO Classification of Tumours Editorial Board. Central Nervous System Tumours. Lyon: International Agency for Research on Cancer; 2021. (WHO Classification of Tumours Series, 5th ed., Vol. 6). https://publications.iarc.fr/601 [Google Scholar]

[CIT0002] 2. Cahill DP, Louis DN, Cairncross JG.. Molecular background of oligodendroglioma: 1p/19q, IDH, TERT, CIC and FUBP1. CNS Oncol. 2015;4(5):287–294. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0003] 3. Kim S, Chowdhury T, Yu HJ, et al. The telomere maintenance mechanism spectrum and its dynamics in gliomas. Genome Med. 2022;14(1):88. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0004] 4. Walsh KM, Wiencke JK, Lachance DH, et al. Telomere maintenance and the etiology of adult glioma. Neuro Oncol. 2015;17(11):1445–1452. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0005] 5. Ackermann S, Fischer M.. Telomere maintenance in pediatric cancer. Int J Mol Sci . 2019;20(23):5836. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0006] 6. Killela PJ, Reitman ZJ, Jiao Y, et al. TERT promoter mutations occur frequently in gliomas and a subset of tumors derived from cells with low rates of self-renewal. Proc Natl Acad Sci U S A. 2013;110(15):6021–6026. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0007] 7. Appin CL, Hong C, Suwala AK, et al. Whole tumor analysis reveals early origin of the TERT promoter mutation and intercellular heterogeneity in TERT expression. Neuro Oncol. 2024;26(4):640–652. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0008] 8. Waitkus MS, Erman EN, Reitman ZJ, Ashley DM.. Mechanisms of telomere maintenance and associated therapeutic vulnerabilities in malignant gliomas. Neuro Oncol. 2024;26(6):1012–1024. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0009] 9. Liu XY, Gerges N, Korshunov A, et al. Frequent ATRX mutations and loss of expression in adult diffuse astrocytic tumors carrying IDH1/IDH2 and TP53 mutations. Acta Neuropathol. 2012;124(5):615–625. [DOI] [PubMed] [Google Scholar]

[CIT0010] 10. Reuss DE, Sahm F, Schrimpf D, et al. ATRX and IDH1-R132H immunohistochemistry with subsequent copy number analysis and IDH sequencing as a basis for an “integrated” diagnostic approach for adult astrocytoma, oligodendroglioma and glioblastoma. Acta Neuropathol. 2015;129(1):133–146. [DOI] [PubMed] [Google Scholar]

[CIT0011] 11. Akyerli CB, Yüksel S, Can O, et al. Use of telomerase promoter mutations to mark specific molecular subsets with reciprocal clinical behavior in IDH mutant and IDH wild-type diffuse gliomas. J Neurosurg. 2018;128(4):1102–1114. [DOI] [PubMed] [Google Scholar]

[CIT0012] 12. Arita H, Ichimura K.. Prognostic significance of TERT promoter mutations in adult-type diffuse gliomas. Brain Tumor Pathol. 2022;39(3):121–129. [DOI] [PubMed] [Google Scholar]

[CIT0013] 13. Lee K, Kim SI, Kim EE, et al. Genomic profiles of IDH-mutant gliomas: MYCN-amplified IDH-mutant astrocytoma had the worst prognosis. Sci Rep. 2023;13(1):6761. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0014] 14. Lee Y, Koh J, Kim SI, et al. The frequency and prognostic effect of TERT promoter mutation in diffuse gliomas. Acta Neuropathol Commun. 2017;5(1):62. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0015] 15. Pekmezci M, Rice T, Molinaro AM, et al. Adult infiltrating gliomas with WHO 2016 integrated diagnosis: additional prognostic roles of ATRX and TERT. Acta Neuropathol. 2017;133(6):1001–1016. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0016] 16. Shi ZF, Li KK, Chan DT, Mao Y, Ng H-K.. Alternative lengthening of telomeres is seen in a proportion of oligodendrogliomas and is associated with a worse prognosis. Neurooncol. Adv.. 2024;6(1):vdae006. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0017] 17. Aihara K, Mukasa A, Nagae G, et al. Genetic and epigenetic stability of oligodendrogliomas at recurrence. Acta Neuropathol Commun. 2017;5(1):18. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0018] 18. Lee J, Putnam AR, Chesier SH, et al. Oligodendrogliomas, IDH-mutant and 1p/19q-codeleted, arising during teenage years often lack TERT promoter mutation that is typical of their adult counterparts. Acta Neuropathol Commun. 2018;6(1):95. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0019] 19. Ceccarelli M, Barthel FP, Malta TM, et al. ; TCGA Research Network. Molecular profiling reveals biologically discrete subsets and pathways of progression in diffuse glioma. Cell. 2016;164(3):550–563. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0020] 20. Qaddoumi I, Orisme W, Wen J, et al. Genetic alterations in uncommon low-grade neuroepithelial tumors: BRAF, FGFR1, and MYB mutations occur at high frequency and align with morphology. Acta Neuropathol. 2016;131(6):833–845. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0021] 21. Ramkissoon LA, Horowitz PM, Craig JM, et al. Genomic analysis of diffuse pediatric low-grade gliomas identifies recurrent oncogenic truncating rearrangements in the transcription factor MYBL1. Proc Natl Acad Sci U S A. 2013;110(20):8188–8193. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0022] 22. Rodriguez FJ, Tihan T, Lin D, et al. Clinicopathologic features of pediatric oligodendrogliomas: a series of 50 patients. Am J Surg Pathol. 2014;38(8):1058–1070. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0023] 23. Dubbink HJ, Atmodimedjo PN, Kros JM, et al. Molecular classification of anaplastic oligodendroglioma using next-generation sequencing: a report of the prospective randomized EORTC Brain Tumor Group 26951 phase III trial. Neuro Oncol. 2016;18(3):388–400. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0024] 24. Arita H, Matsushita Y, Machida R, et al. TERT promoter mutation confers favorable prognosis regardless of 1p/19q status in adult diffuse gliomas with IDH1/2 mutations. Acta Neuropathol Commun. 2020;8(1):201. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0025] 25. Lee Y, Park CK, Park SH.. Prognostic impact of TERT promoter mutations in adult-type diffuse gliomas based on WHO2021 criteria. Cancers (Basel). 2024;16(11):2032. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0026] 26. Capper D, Jones DTW, Sill M, et al. DNA methylation-based classification of central nervous system tumours. Nature. 2018;555(7697):469–474. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0027] 27. Rahmanzade R, Pfaff E, Banan R, et al. Genetical and epigenetical profiling identifies two subgroups of pineal parenchymal tumors of intermediate differentiation (PPTID) with distinct molecular, histological and clinical characteristics. Acta Neuropathol. 2023;146(6):853–856. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0028] 28. Capper D, Stichel D, Sahm F, et al. Practical implementation of DNA methylation and copy-number-based CNS tumor diagnostics: the Heidelberg experience. Acta Neuropathol. 2018;136(2):181–210. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0029] 29. Shirahata M, Ono T, Stichel D, et al. Novel, improved grading system(s) for IDH-mutant astrocytic gliomas. Acta Neuropathol. 2018;136(1):153–166. [DOI] [PubMed] [Google Scholar]

[CIT0030] 30. Nuechterlein N, Cimino S, Shelbourn A, et al. HOXD12 defines an age-related aggressive subtype of oligodendroglioma. Acta Neuropathol. 2024;148(1):41. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0031] 31. Braun DM, Chung I, Kepper N, Deeg KI, Rippe K.. TelNet - a database for human and yeast genes involved in telomere maintenance. BMC Genet. 2018;19(1):32. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0032] 32. Wen PY, van den Bent M, Youssef G, et al. RANO 2.0: update to the response assessment in neuro-oncology criteria for high- and low-grade gliomas in adults. J Clin Oncol. 2023;41(33):5187–5199. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0033] 33. Castelo-Branco P, Choufani S, Mack S, et al. Methylation of the TERT promoter and risk stratification of childhood brain tumours: an integrative genomic and molecular study. Lancet Oncol. 2013;14(6):534–542. [DOI] [PubMed] [Google Scholar]

[CIT0034] 34. Kouroukli AG, Fischer A, Kretzmer H, et al. The DNA methylation status of the TERT promoter differs between subtypes of mature B-cell lymphomas. Blood Cancer J. 2023;13(1):98. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0035] 35. Rowland TJ, Bonham AJ, Cech TR.. Allele-specific proximal promoter hypomethylation of the telomerase reverse transcriptase gene (TERT) associates with TERT expression in multiple cancers. Mol Oncol. 2020;14(10):2358–2374. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0036] 36. Heidenreich B, Rachakonda PS, Hosen I, et al. TERT promoter mutations and telomere length in adult malignant gliomas and recurrences. Oncotarget. 2015;6(12):10617–10633. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0037] 37. Brat DJ, Verhaak RG, Aldape KD, et al. ; Cancer Genome Atlas Research Network. Comprehensive, integrative genomic analysis of diffuse lower-grade gliomas. N Engl J Med. 2015;372(26):2481–2498. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0038] 38. Otsuji R, Hata N, Yamamoto H, et al. Hemizygous deletion of cyclin-dependent kinase inhibitor 2A/B with p16 immuno-negative and methylthioadenosine phosphorylase retention predicts poor prognosis in IDH-mutant adult glioma. Neurooncol Adv. 2024;6(1):vdae069. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0039] 39. Ippen FM, Hielscher T, Friedel D, et al. The prognostic impact of CDKN2A/B hemizygous deletions in IDH-mutant glioma. Neuro Oncol. 2024;27(3):743–754. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0040] 40. Byeon Y, Lee C, Jeon J, et al. Long-term outcomes of CNS WHO grade 2 oligodendroglioma in adult patients: a single-institution experience. Discov Oncol. 2024;15(1):268. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0041] 41. Mellinghoff IK, van den Bent MJ, Blumenthal DT, et al. ; INDIGO Trial Investigators. Vorasidenib in IDH1- or IDH2-mutant low-grade glioma. N Engl J Med. 2023;389(7):589–601. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0042] 42. Gatto L, Di Nunno V, Tosoni A, et al. Vorasidenib in IDH1/2-mutant low-grade glioma: the grey zone of patient’s selection. Front Oncol. 2024;13:1339266. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0043] 43. Exner ND, Valenzuela JAC, Abou-El-Ardat K, et al. Deep sequencing of a recurrent oligodendroglioma and the derived xenografts reveals new insights into the evolution of human oligodendroglioma and candidate driver genes. Oncotarget. 2019;10(38):3641–3653. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0044] 44. Suzuki H, Aoki K, Chiba K, et al. Mutational landscape and clonal architecture in grade II and III gliomas. Nat Genet. 2015;47(5):458–468. [DOI] [PubMed] [Google Scholar]

[CIT0045] 45. Watanabe T, Nobusawa S, Kleihues P, Ohgaki H.. IDH1 mutations are early events in the development of astrocytomas and oligodendrogliomas. Am J Pathol. 2009;174(4):1149–1153. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0046] 46. Lee DD, Komosa M, Sudhaman S, et al. Dual role of allele-specific DNA hypermethylation within the TERT promoter in cancer. J Clin Invest. 2021;131(21):e146915. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0047] 47. Zacher A, Kaulich K, Stepanow S, et al. Molecular diagnostics of gliomas using next generation sequencing of a glioma-tailored gene panel. Brain Pathol. 2017;27(2):146–159. [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0048] 48. Dono A, Moosvi AM, Goli PS, et al. TERT immunohistochemistry as a surrogate marker for TERT promoter mutations in infiltrating gliomas. Appl Immunohistochem Mol Morphol. 2023;31(5):288–294. [DOI] [PMC free article] [PubMed] [Google Scholar]

PERMALINK

Distinct molecular profile and outcome of oligodendroglioma, IDH-mutant, 1p/19q-codeleted, and TERTp-wildtype: A grade 1 oligodendroglioma of young patients?

Filippo Nozzoli

Ramin Rahmanzade

Simone Schmid

Leonille Schweizer

Daniel Schrimpf

Dennis Friedel

Kirsten Göbel

David E Reuss

Rouzbeh Banan

Philipp Sievers

Stefan Pusch

Henri Bogumil

Felix Hinz

Abigail K Suwala

Fuat Kaan Aras

Lukas Friedrich

Simona Osella-Abate

Alessia Andrea Ricci

Alessandra Macciotta

Thorsten Simon

Gudrun Fleischhack

Kathy Keyvani

Jordan R Hansford

Dong-Anh Khuong-Quang

Philippe Schucht

Theoni Maragkou

Tareq A Juratli

Matthias Meinhardt

Sabrina Zechel

Christine Stadelmann

Roland Coras

Oliver W Sakowitz

Benjamin Goeppert

Jens Schittenhelm

Nima Etminan

Miriam Ratliff

Christel Herold-Mende

Stefan M Pfister

Wolfgang Wick

Sandro M Krieg

Andreas von Deimling

Felix Sahm

Luca Bertero

Abstract

Background

Methods

Results

Conclusions

Key Points.

Importance of the Study.

Materials and Methods

Collection of Tissue Samples and Clinical Data

Histology and Immunohistochemistry

TERTp Sanger Sequencing

DNA Methylation Profiling, DNA Methylation Analysis of TERTp and HOXD12, and Copy Number Analysis

WES and Telomere Maintenance-Related Genes Mutational Analysis

Statistical Analysis

Results

Demographic and Clinical Characteristics of the Whole Cohort

Table 1.

Histological, Immunohistochemical, and Baseline Molecular Review

Sequencing Analysis Identifies TERTp-Wildtype Status in the Vast Majority of Young Patients and WES Analysis Revealed Absence of Mutations in Telomere Maintenance-Related Genes of TERTp-Wildtype Cases

Figure 1.

Epigenetic Profiling Reveals Distinct Clustering of TERTp-Wildtype and TERTp-Mutant Oligodendrogliomas

Figure 2.

Figure 3.

Methylation Analysis of Upstream and Proximal TERTp Regions

Methylation Analysis of the HOXD12 Gene

PFS Analysis Indicated a Favorable Impact on PFS of TERTp-Wildtype Status in Oligodendroglioma

Table 2:

Figure 4.

Discussion

Supplementary material

Acknowledgments

Contributor Information

Conflict of interest statement

Author Contributions

Ethics Statement