Diffuse Midline Glioma H3 K27M Research Articles

The Role of Radiotherapy, Chemotherapy, and Targeted Therapies in Adult Intramedullary Spinal Cord Tumors.

Intramedullary primary spinal cord tumors are rare in adults and their classification has recently evolved. Their treatment most frequently relies on maximal safe surgical resection. Herein, we review, in light of the WHO 2021 classification of central nervous system tumors, the knowledge regarding the role of radiotherapy and systemic treatments in spinal ependymomas, spinal astrocytomas (pilocytic astrocytoma, diffuse astrocytoma, spinal glioblastoma IDH wildtype, diffuse midline glioma H3-K27M altered, and high-grade astrocytoma with piloid features), neuro-glial tumors (ganglioglioma and diffuse leptomeningeal glioneuronal tumor), and hemangioblastomas. In spinal ependymomas, radiotherapy is recommended for incompletely resected grade 2 tumors, grade 3 tumors, and recurrent tumors not amenable to re-surgery. Chemotherapy is used in recurrent cases. In spinal astrocytomas, radiotherapy is recommended for incompletely resected grade 2 astrocytomas and grade 3 or 4 tumors as well as recurrent tumors. Chemotherapy is indicated for newly diagnosed high-grade astrocytomas and recurrent cases. In hemangioblastomas not amenable to surgery, radiotherapy is an effective alternative option. Targeted therapies are playing an increasingly important role in the management of some intramedullary primary spinal cord tumor subtypes. BRAF and/or MEK inhibitors have demonstrated efficacy in pilocytic astrocytomas and glioneuronal tumors, belzutifan in von Hippel-Lindau-related hemangioblastomas, and promising results have been reported with ONC201 in diffuse midline glioma H3-K27M altered.

Spatial transcriptomics reveals niche-specific enrichment and vulnerabilities of radial glial stem-like cells in malignant gliomas

Diffuse midline glioma-H3K27M mutant (DMG) and glioblastoma (GBM) are the most lethal brain tumors that primarily occur in pediatric and adult patients, respectively. Both tumors exhibit significant heterogeneity, shaped by distinct genetic/epigenetic drivers, transcriptional programs including RNA splicing, and microenvironmental cues in glioma niches. However, the spatial organization of cellular states and niche-specific regulatory programs remain to be investigated. Here, we perform a spatial profiling of DMG and GBM combining short- and long-read spatial transcriptomics, and single-cell transcriptomic datasets. We identify clinically relevant transcriptional programs, RNA isoform diversity, and multi-cellular ecosystems across different glioma niches. We find that while the tumor core enriches for oligodendrocyte precursor-like cells, radial glial stem-like (RG-like) cells are enriched in the neuron-rich invasive niche in both DMG and GBM. Further, we identify niche-specific regulatory programs for RG-like cells, and functionally confirm that FAM20C mediates invasive growth of RG-like cells in a neuron-rich microenvironment in a human neural stem cell derived orthotopic DMG model. Together, our results provide a blueprint for understanding the spatial architecture and niche-specific vulnerabilities of DMG and GBM.

OTHR-23. Development of a cerebrospinal fluid liquid biopsy platform in pediatric patients with central nervous system tumors

Abstract Pediatric central nervous system (CNS) tumors carry high morbidity and mortality. The advent of targeted agents is aiming to change that through individualized, less invasive, and real-time molecular profiling. We successfully developed a cerebrospinal fluid (CSF) liquid biopsy (LB) platform combining low-pass whole genome sequencing (WGS) and targeted mutation and gene fusion analysis of cell-free (cf) DNA. WGS libraries were constructed with the xGen Prism DNA Library Prep Kit using 5ng of input cfDNA and paired-end sequenced (Illumina NextSeq 500) for an average 0.5x coverage across the genome. Copy number (CN) profiles were analyzed using the ichorCNA R package and compared with CN abnormalities of the primary tumors detected with CytoScanHD or Oncoscan arrays. Selected cases were analyzed for mutations or gene fusions using a custom glioma hybrid capture-based panel (Twist Bioscience) sequenced to 500-1000x across targeted regions. Mutations identified in LBs were compared with primary tumor OncoKids NGS panel results. CSF LBs from 44 tumor cases and 15 non-tumor controls were analyzed. Sixteen primary tumors had copy number changes, 10 had cfDNA detected in the LB across various primary tumor diagnoses (AT/RT, diffuse midline glioma, ependymoma, high-grade glioma, medulloblastoma, pilocytic astrocytoma). Four primary tumors had sequence alterations from the custom panel, two with detectable cfDNA (diffuse midline glioma H3K27M variant allele frequency (VAF) 49% and low-grade glioma BRAFV600E VAF 1.7%). Three patients had TP53 variants detected, all ultimately germline. Controls were negative across WGS and hybrid gene capture. Tumor DNA is detectable by both WGS and hybrid gene capture. Various histologic subtypes are detectable including embryonal and glioneuronal. CSF seems more enriched for cfDNA in high grade versus low grade tumors. These data suggest that NGS-based LB assays may be used to monitor pediatric patients with a variety of CNS tumors, from diagnosis through treatment and recurrence.

Tumor treating fields therapy is feasible and safe in a 3-year-old patient with diffuse midline glioma H3K27M — a case report

Since high grade gliomas are aggressive brain tumors, intensive search for new treatment options is ongoing. For adult patients with newly diagnosed (ndGBM) and recurrent glioblastoma (rGBM), low intensity intermediate frequency alternating electric fields, known as tumor treating fields (TTFields) have been established as a new treatment modality. Tumor treating fields significantly increase survival rates in combination with adjuvant temozolomide (TMZ) in adult and GBM patients. Here, we report about feasibility and safety of treatment on a pediatric patient with diffuse midline glioma who is receiving TTFields therapy in combination with temozolomide.

Molecular diagnostics helps to identify distinct subgroups of spinal astrocytomas

Primary spinal cord astrocytomas are rare, hence few data exist about the prognostic significance of molecular markers. Here we analyze a panel of molecular alterations in association with the clinical course. Histology and genome sequencing was performed in 26 spinal astrocytomas operated upon between 2000 and 2020. Next-generation DNA/RNA sequencing (NGS) and methylome analysis were performed to determine molecular alterations. Histology and NGS allowed the distinction of 5 tumor subgroups: glioblastoma IDH wildtype (GBM); diffuse midline glioma H3 K27M mutated (DMG-H3); high-grade astrocytoma with piloid features (HAP); diffuse astrocytoma IDH mutated (DA), diffuse leptomeningeal glioneural tumors (DGLN) and pilocytic astrocytoma (PA). Within all tumor entities GBM (median OS: 5.5 months), DMG-H3 (median OS: 13 months) and HAP (median OS: 8 months) showed a fatal prognosis. DMG-H3 tend to emerge in adolescence whereas GBM and HAP develop in the elderly. HAP are characterized by CDKN2A/B deletion and ATRX mutation. 50% of PA tumors carried a mutation in the PIK3CA gene which is seemingly associated with better outcome (median OS: PIK3CA mutated 107.5 vs 45.5 months in wildtype PA). This exploratory molecular profiling of spinal cord astrocytomas allows to identify distinct subgroups by combining molecular markers and histomorphology. DMG-H3 tend to develop in adolescence with a similar dismal prognosis like GBM and HAP in the elderly. We here describe spinal HAP with a distinct molecular profile for the first time.

Molecular characteristics of H3 K27M mutation gliomas in Chinese adults.

e14018 Background: Diffuse midline glioma H3 K27M–mutant is a specific entity added to the 2016 update of the WHO classification of CNS tumors. H3K27M-mutant gliomas are diagnosed primarily in children and adolescents with TP53 and/or ATRX mutations. However, the characteristics of H3 K27M-mutant gliomas in adults have not been explicitly described. Methods: We performed the 131-gene panel targeted sequencing on tumor samples from 33 adults H3 K27M-mutant gliomas( > 18 years) and 13 children and adolescents H3 K27M-mutant gliomas(≤18 years) in a CAP certified laboratory. Somatic mutations, copy number variations, and fusion genes were detected following the standard operating procedure (SOP). The MS-based assay measured MGMT promoter methylation. We calculated the tumor location and the median age in different cohorts. Results: In our adult cohort, 22/33（66.7%）had a midline location（spinal cord n = 2, thalamus n = 7, brainstem n = 6, cerebellum n = 3, pineal region n = 1, Basal ganglia region n = 3）, 6/33（18.1%）had a non-midline location (Lateral ventricle n = 2, Cerebral hemispheres n = 4). In the children and adolescents cohort, 11/13（84.6%）occurred in midline location, 1/13(7.7%) occurred in the Lateral ventricle. MGMT promoter methylation did not differ in adult and pediatric H3 K27M-mutant gliomas (12.1% vs. 0). H3 K27M-mutant adult gliomas significantly co-occurred with the NF1 mutation(P = 0.008937). The median age of H3 K27M-mutant adult gliomas with NF1 modification (13/33, 39.4%) is higher than the NF1 wild type (49 years vs. 38 years, P = 0.107), although the difference has no statistical significance. Conclusions: In Chinese adults, as in children, H3 K27M mutation gliomas are characterized by a constant midline location, low rate of MGMT promoter methylation. Inconsistently, H3 K27M mutant adult gliomas are featured by a higher rate of NF1 mutations. Our molecular profiling analysis revealed the H3 K27M mutation in adult gliomas. Our research suggests potential molecular pathogenesis of H3K27M mutant adult gliomas and identifies more therapeutic targets for precision medicine.

Clinical and Genetic Features of Brainstem Glioma in Adults: A Report of 50 Cases in a Single Center.

Background and PurposeBrainstem gliomas (BSGs) in adults are rare brain tumors with dismal outcomes. The aim of this study was to determine the clinical and genetic features in a series of BSGs and their association with the prognosis.MethodsFifty patients who underwent a stereotactic biopsy between January 2016 and April 2018 at a single institution were collected. Data on clinicopathological characteristics were analyzed and factors associated with patient survival were identified using a Cox regression model.ResultsThe median age at diagnosis was 55.5 years, and 62% of the patients were male. Glioblastoma (44%) accounted for the largest proportion of BSGs, and oligodendroglioma (2 of 50) was rarely encountered. The IDH mutation (6 of 44) occurred infrequently in astrocytomas, and IDH-mutant tumors harbored both ATRX loss and MGMT promoter methylation at a relatively low level. Wild-type IDH astrocytomas were identified as having high rates of 1p/19q codeletion (5 of 38) and loss of heterozygosity 1p (8 of 38) or 19q (8 of 38) only. In diffuse midline glioma H3K27M mutant, MGMT promoter methylation occurred in three of four cases. Patients were offered radiotherapy and/or concurrent/adjuvant temozolomide chemotherapy, and their median survival time was 13 months. Multivariate analysis revealed that a low tumor grade, absence of tumor enhancement, duration of symptoms ≥3 months, Karnofsky performance status ≥70, and ATRX loss conferred a survival advantage.ConclusionsAdult BSGs showed different molecular genetic characteristics, but also resembled supratentorial gliomas in their clinical features associated with oncological outcomes.

Radiologic findings and the molecular expression profile of diffuse midline glioma H3 K27M mutant.

Diffuse midline glioma H3 K27M-mutant (DMG) are reported to show heterogeneous radiologic imaging features in children. We hypothesized that other genetic mutations may contribute to this heterogeneity. To describe the magnetic resonance imaging (MRI) findings of DMG in adult patients and to correlate the imaging findings with the molecular expression profile. Eighteen patients with pathologically proven DMG were enrolled. On preoperative MRI, the following were evaluated: location; size of the lesion; ratio of non-enhancing (NE) and contrast-enhancing (CE) area; presence of cortical invasion and necrotic component; maximum relative cerebral blood volume ratio (rCBV ratio) of NE and CE portions; and minimum apparent diffusion coefficient (ADC) of NE and CE portions, among others. Molecular profiles including ATRX expression and p53 mutation were reviewed to find correlation with imaging features. Thalamus was the most commonly involved location, followed by pons and tectum. Five patients showed loss of normal ATRX expression. p53 mutation was positive in 12 patients. 40% of normal ATRX expression patients had cortical involvement and 20% had leptomeningeal seeding; none of the patients with ATRX loss had cortical involvement or leptomeningeal seeding. Patients with normal ATRX expression showed significantly higher rCBV ratio and lower ADC value in the NE area than patients with ATRX loss (P=0.04, 0.016). p53 mutation status did not correlate with any imaging finding. Cortical invasion, leptomeningeal tumor spread, lower ADC value and higher rCBV ratio in NE areas of DMG may be related to normal expression of ATRX.

The prognosis of diffuse midline glioma H3 K27M mutant.

e13548 Background: Diffuse Midline Glioma is rare spinal cord primary tumor. Unfortunately it is known that the prognosis is poor, and it was added to the WHO guidelines in 2016 as a grade IV. It is so rare that the prognosis of the diffuse midline glioma in spinal cord is not well known yet. So we want to analyze the prognosis of the spinal cord diffuse midline glioma and find out about the molecular profile. Methods: We retrospectively reviewed of 10 diffuse midline glioma H3-K27M mutant patients who underwent surgery in a single institute, 2015.09~2018.04. We analyzed the demographic data, overall survival, progression free survival and molecular profile which includes PTEN, BRAF, EGFR, MGMT methylation status, c-MET, IDH1, 1p/19q deletion. Results: Mean age was 44.8 yr; male to female ratio was 5:5. Tumor was located conus medullaris (8), CT Junction(1), Cervical(1). One was given gross total resection and the other was a partial resection or biopsy. All patient were treated with CCRT. Medial overall survival was 47.8 months, and median progression free survival was 21 months. One case each was found for BRAF, C-MET, IDH1, PTEN and EGFR. Conclusions: This study was conducted on patients collected for a relatively short period. This study reported survival analysis and molecular profile. These mutations are known to be mainly associated with MAPK pathway. So there may be a correlation between H3-K27M and MAPK pathway. Results indicating the association of MAPK and H3K27M can be found in some literature. Further research is needed.

Correction: Detection of histone H3 K27M mutation and post-translational modifications in pediatric diffuse midline glioma via tissue immunohistochemistry informs diagnosis and clinical outcomes.

[This corrects the article DOI: 10.18632/oncotarget.26430.].

Detection of histone H3 K27M mutation and post-translational modifications in pediatric diffuse midline glioma via tissue immunohistochemistry informs diagnosis and clinical outcomes.

Pediatric diffuse midline glioma is a highly morbid glial neoplasm that may arise in the thalamus or brainstem (also known as diffuse intrinsic pontine glioma or DIPG). Because tumor anatomic location precludes surgical resection, diagnosis and treatment is based on MR imaging and analysis of biopsy specimens. Up to 80% of pediatric diffuse midline gliomas harbor a histone H3 mutation resulting in the replacement of lysine 27 with methionine (K27M) in genes encoding histone H3 variant H3.3 (H3F3A) or H3.1 (HIST1H3B). H3K27M mutant glioma responds more poorly to treatment and is associated with worse clinical outcome than wild-type tumors, so mutation detection is now diagnostic for a new clinical entity, diffuse midline glioma H3K27M mutant, as defined in the most recent WHO classification system. We previously reported patterns of histone H3 trimethylation (H3K27me3) and acetylation (H3K27Ac) associated with H3K27M mutation that impact transcription regulation and contribute to tumorigenesis. Given the clinical implications of the H3K27M mutation and these associated H3 post-translational modifications (PTMs), we set to determine whether they can be characterized via immunohistochemistry (IHC) in a cohort of pediatric glioma (n = 69) and normal brain tissue (n = 4) specimens. We observed 100% concordance between tissue IHC and molecular sequencing for detecting H3K27M mutation. In turn, H3K37M and H3K27me3 results, but not H3K27Ac staining patterns, were predictive of clinical outcomes. Our results demonstrate H3K27M and H3K27me3 staining of pediatric glioma tissue may be useful for diagnosis, stratification to epigenetic targeted therapies, and longitudinal monitoring of treatment response.

Clinical significance of the 2016 WHO classification in Japanese patients with gliomas.

In this study, we retrospectively compared the prognostic value of the 2016 WHO classification with the former classification in 387 patients with glioma treated at our institution. According to the new classification, diagnoses included oligodendroglioma with isocitrate dehydrogenase (IDH) mutation and 1p/19q co-deletion (5.4%), anaplastic oligodendroglioma with IDH mutation and 1p/19q co-deletion (3.4%), diffuse astrocytoma IDH-mutated (3.9%), anaplastic astrocytoma IDH-mutated (2.8%), glioblastoma IDH-mutated (7.8%), glioblastoma IDH-wildtype (58.4%), diffuse midline glioma H3 K27M mutation (2.6%), oligodendroglioma NOS (1.3%), anaplastic oligodendroglioma NOS (0.8%), diffuse astrocytoma IDH-wildtype (2.8%), and anaplastic astrocytoma IDH-wildtype (10.9%). The prognoses of IDH-mutated astrocytomas clearly varied according to tumor grade. However, we identified no survival difference between IDH-wildtype anaplastic astrocytomas and glioblastomas; additionally, these tumors showed similar gene expression profiles. After exclusion of those without 1p/19q co-deletion, patients with oligodendroglial tumors showed excellent survival regardless of tumor grade. Our evaluation of chromosomal aberrations suggests that the MAPK/PI3K pathway plays a role in acquired malignancy of astrocytic tumors, whereas TP53 participates in tumorigenesis. We suspect the RB pathway also plays a role in tumorigenesis of IDH-mutated gliomas. The new WHO classification more clearly reflects the tumorigenesis of gliomas and improves the prognostic power of classification.

GENE-06. CO-OCCURRENCE OF DOUBLE MUTATION H3F3A/BRAF IN PEDIATRIC GANGLIOGLIOMAS

AbstractGrade I or III ganglioglioma (GG) is characterized by alterations in the MAPK pathway, including BRAF mutation. Diffuse midline glioma H3 K27M mutated was added to the WHO 2016 classification as a new grade IV entity. A co-occurrence of H3F3A/BRAF mutations has been reported in midline tumors. Firstly, we searched for BRAF V600E and H3 K27M mutations in a series of 54 pediatric midline grade I GG to determine the frequency of double mutations in grade I GG. We then studied the clinico-radiological and histo-molecular features of 12 grade I to III double-mutated tumors to explore the therapeutic and prognostic relevance. The frequency of the co-occurrence of H3F3A/BRAF mutations in grade I midline GG at diagnosis was 9.3%. Double-immunostaining revealed that BRAF V600E and H3 K27M mutant proteins colocalized in both the glial and neuronal components, The series of double-mutated GG included 8 grade I, and 4 grade III at diagnosis. The median survival was 8 years. Three grade I tumors showed a malignant transformation at 0.5, 3.5 and 7 years and two of them showed a loss of the BRAF mutation in recurrent tumor samples. Five patients with grade I were alive with stable disease without adjuvant therapy at the last follow-up. One grade III showed a paradoxical response under BRAF inhibitor. In this work we stress that H3F3A mutation can occur, in association with the BRAF mutation, in grade I GG, and that these have a better spontaneous outcome than classic diffuse midline H3 K27M-mutant gliomas. These data highlight the importance of an integrated histomolecular diagnosis especially in the context of targeted therapy.