Hemispheric High-grade Gliomas Research Articles

Specific brain MRI features of constitutional mismatch repair deficiency syndrome in children with high-grade gliomas.

Children with constitutional mismatch repair deficiency (CMMRD) syndrome have an increased risk of high-grade gliomas (HGG), and brain imaging abnormalities. This study analyzes brain imaging features in CMMRD syndrome children versus those with HGG without CMMRD. Retrospective comparative analysis of brain imaging in 30 CMMRD children (20 boys, median age eight years, 22 with HGG), seven with Lynch syndrome (7 HGG), 39 with type 1 neurofibromatosis (NF1) (four with HGG) and 50 with HGG without MMR or NF1 pathogenic variant ("no-predisposition" patients). HGG in CMMRD and Lynch patients were predominantly hemispheric (versus midline) compared to NF1 and no-predisposition patients (91% and 86%, vs 25% and 54%, p = 0.004). CMMRD-associated tumors often had ill-defined boundaries (p = 0.008). All CMMRD patients exhibited at least one developmental venous anomaly (DVA), versus 14%, 10%, and 6% of Lynch, NF1, and no-predisposition patients (p < 0.0001). Multiple DVAs were observed in 83% of CMMRD patients, one NF1 patient (3%), and never in other groups (p < 0.0001). Cavernomas were discovered in 21% of CMMRD patients, never in other groups (p = 0.01). NF1-like focal areas of high T2-FLAIR signal intensity (FASI) were more prevalent in CMMRD patients than in Lynch or no-predisposition patients (50%, vs 20% and 0%, respectively, p < 0.0001). Subcortical and ill-limited FASI, possibly involving the cortex, were specific to CMMRD (p < 0.0001) and did not evolve in 93% of patients (13/14). Diffuse hemispherically located HGG associated with multiple DVAs, cavernomas, and NF1-like or subcortical FASI strongly suggests CMMRD syndrome compared to children with HGG in other contexts. The radiologic suggestion of CMMRD syndrome when confronted with HGGs in children may prompt genetic testing. This can influence therapeutic plans. Therefore, imaging features could potentially be incorporated into CMMRD testing recommendations. Using imaging to detect CMMRD syndrome early may improve patient care. CMMRD features include: hemispheric HGG with multiple developmental venous anomalies and NF1-like or subcortical areas with high T2-FLAIR intensity. We propose novel imaging features to improve the identification of potential CMMRD patients.

Specific brain MRI features of constitutional mismatch repair deficiency syndrome in children with high-grade gliomas.

Children with constitutional mismatch repair deficiency (CMMRD) syndrome have an increased risk of high-grade gliomas (HGG), and brain imaging abnormalities. This study analyzes brain imaging features in CMMRD syndrome children versus those with HGG without CMMRD. Retrospective comparative analysis of brain imaging in 30 CMMRD children (20 boys, median age eight years, 22 with HGG), seven with Lynch syndrome (7 HGG), 39 with type 1 neurofibromatosis (NF1) (four with HGG) and 50 with HGG without MMR or NF1 pathogenic variant ("no-predisposition" patients). HGG in CMMRD and Lynch patients were predominantly hemispheric (versus midline) compared to NF1 and no-predisposition patients (91% and 86%, vs 25% and 54%, p = 0.004). CMMRD-associated tumors often had ill-defined boundaries (p = 0.008). All CMMRD patients exhibited at least one developmental venous anomaly (DVA), versus 14%, 10%, and 6% of Lynch, NF1, and no-predisposition patients (p < 0.0001). Multiple DVAs were observed in 83% of CMMRD patients, one NF1 patient (3%), and never in other groups (p < 0.0001). Cavernomas were discovered in 21% of CMMRD patients, never in other groups (p = 0.01). NF1-like focal areas of high T2-FLAIR signal intensity (FASI) were more prevalent in CMMRD patients than in Lynch or no-predisposition patients (50%, vs 20% and 0%, respectively, p < 0.0001). Subcortical and ill-limited FASI, possibly involving the cortex, were specific to CMMRD (p < 0.0001) and did not evolve in 93% of patients (13/14). Diffuse hemispherically located HGG associated with multiple DVAs, cavernomas, and NF1-like or subcortical FASI strongly suggests CMMRD syndrome compared to children with HGG in other contexts. The radiologic suggestion of CMMRD syndrome when confronted with HGGs in children may prompt genetic testing. This can influence therapeutic plans. Therefore, imaging features could potentially be incorporated into CMMRD testing recommendations. Using imaging to detect CMMRD syndrome early may improve patient care. CMMRD features include: hemispheric HGG with multiple developmental venous anomalies and NF1-like or subcortical areas with high T2-FLAIR intensity. We propose novel imaging features to improve the identification of potential CMMRD patients.

CNSC-01. GABAERGIC NEURON-TO-GLIOMA SYNAPSES IN DIFFUSE MIDLINE GLIOMAS

Abstract High-grade gliomas include clinically and molecularly distinct subtypes that stratify by anatomical location into diffuse midline gliomas (DMG) such as diffuse intrinsic pontine glioma (DIPG) and hemispheric high-grade gliomas. Neuronal activity drives high-grade glioma progression both through paracrine signaling and direct neuron-to-glioma synapses. Glutamatergic, AMPA receptor-dependent synapses between neurons and malignant glioma cells have been demonstrated in both pediatric and adult high-grade gliomas, but neuron-to-glioma synapses mediated by other neurotransmitters remain largely unexplored. Using whole-cell patch clamp electrophysiology, in vivo optogenetics and patient-derived glioma xenograft models, we have now identified functional, tumor-promoting GABAergic neuron-to-glioma synapses mediated by GABAA receptors in DMGs. GABAergic input has a depolarizing effect on DMG cells due to NKCC1 expression and consequently elevated intracellular chloride concentration in DMG tumor cells. As membrane depolarization increases glioma proliferation, we find that the activity of GABAergic interneurons promotes DMG proliferation in vivo. Increasing GABA signaling with the benzodiazepine lorazepam – a positive allosteric modulator of GABAA receptors commonly administered to children with DMG for nausea or anxiety - increases GABAA receptor conductance and increases glioma proliferation in orthotopic xenograft models of DMG. Conversely, levetiracetam, an anti-epileptic drug that attenuates GABAergic neuron-to-glioma synaptic currents, reduces glioma proliferation in patient-derived DMG xenografts and extends survival of mice bearing DMG xenografts. Concordant with gene expression patterns of GABAA receptor subunit genes across subtypes of glioma, depolarizing GABAergic currents were not found in hemispheric high-grade gliomas. Accordingly, neither lorazepam nor levetiracetam influenced the growth rate of hemispheric high-grade glioma patient-derived xenograft models. Retrospective real-world clinical data are consistent with these conclusions and should be replicated in future prospective clinical studies. Taken together, these findings uncover GABAergic synaptic communication between GABAergic interneurons and DMG cells, underscoring a tumor subtype-specific mechanism of brain cancer neurophysiology with important potential implications for commonly used drugs in this disease context.

NSD1 Mutations and Pediatric High-Grade Gliomas: A Comparative Genomic Study in Primary and Recurrent Tumors.

Pediatric high-grade gliomas represent a heterogeneous group of tumors with a wide variety of molecular features. We performed whole exome sequencing and methylation profiling on matched primary and recurrent tumors from four pediatric patients with hemispheric high-grade gliomas. Genetic analysis showed the presence of some variants shared between primary and recurrent tumors, along with other variants exclusive of primary or recurrent tumors. NSD1 variants, all novel and not previously reported, were present at high frequency in our series (100%) and were all shared between the samples, independently of primary or recurrence. For every variant, in silico prediction tools estimated a high probability of altering protein function. The novel NSD1 variant (c.5924T > A; p.Leu1975His) was present in one in four cases at recurrence, and in two in four cases at primary. The novel NSD1 variant (c.5993T > A; p.Met1998Lys) was present in one in four cases both at primary and recurrence, and in one in four cases only at primary. The presence of NSD1 mutations only at recurrence may suggest that they can be sub-clonal, while the presence in both primary and recurrence implies that they can also represent early and stable events. Furthermore, their presence only in primary, but not in recurrent tumors, suggest that NSD1 mutations may also be influenced by treatment.

IMMU-09. IMMUNOLOGICAL CHARACTERIZATION OF PEDIATRIC BRAIN TUMORS HAS CLINICAL IMPLICATIONS FOR PATIENT MANAGEMENT AND PROGNOSIS

Abstract The tumor immune microenvironment (TIME) is a growing area of interest, however, the extent of immune activation in childhood CNS tumors is unknown. Although immunotherapy has not gained success in most CNS cancers, our group described gliomas with MMRD which exhibit hypermutation and favorable responses to immune checkpoint inhibition (ICI). Therefore, detailed characterization of the CNS TIME is key for the development of novel immunotherapeutic strategies and application of existing ones in childhood brain tumors. We developed a clinical NanoString immune-oncology panel that includes markers reflecting cell types, therapeutic targets, and cellular pathways, as well as the 18-gene tumor inflammation signature (TIS), a biomarker for ICI response. We tested over 500 brain tumors, including 266 low-grade gliomas (LGG), 170 high-grade gliomas (HGG), 91 MMRD tumors, 16 ependymomas, 46 medulloblastomas, and 36 non-tumor brain samples. Overall, ependymomas and medulloblastomas had low levels of inflammation, although SHH medulloblastomas had higher inflammation than other subtypes. IDH-mutant LGG were immunologically cold, while many gliomas with pediatric-LGG mutations had high levels of inflammation, including upregulation of immune checkpoints – indicating that ICI may be an effective strategy. Interestingly, in pediatric-LGG inflammation impacted outcome in tumors with the same genetic alterations. BRAF V600E-mutant LGG exhibiting high TIS had inferior prognosis (p = 0.02), while no such relationship was observed in BRAF-fused tumors. Diffuse midline gliomas had higher inflammation than hemispheric HGG, indicating that these tumors are not immunologically cold, as has been previously reported. In MMRD tumors treated with ICI, high TIS correlated with improved survival and was independent from hypermutation and mutational burden. Furthermore, MMRD gliomas had high expression of several other immune checkpoints including LAG3, suggesting its value as an additional therapeutic target. In summary, characterization of the TIME across pediatric brain tumors provides potential prognostic clues and suggest treatment strategies for further investigation.

Topographic correlates of driver mutations and endogenous gene expression in pediatric diffuse midline gliomas and hemispheric high-grade gliomas

We evaluate the topographic distribution of diffuse midline gliomas and hemispheric high-grade gliomas in children with respect to their normal gene expression patterns and pathologic driver mutation patterns. We identified 19 pediatric patients with diffuse midline or high-grade glioma with preoperative MRI from tumor board review. 7 of these had 500 gene panel mutation testing, 11 patients had 50 gene panel mutation testing and one 343 gene panel testing from a separate institution were included as validation set. Tumor imaging features and gene expression patterns were analyzed using Allen Brain Atlas. Twelve patients had diffuse midline gliomas and seven had hemispheric high-grade gliomas. Three diffuse midline gliomas had the K27M mutation in the tail of histone H3 protein. All patients undergoing 500 gene panel testing had additional mutations, the most common being in ACVR1, PPM1D, and p53. Hemispheric high-grade gliomas had either TP53 or IDH1 mutation and diffuse midline gliomas had H3 K27M-mutation. Gene expression analysis in normal brains demonstrated that genes mutated in diffuse midline gliomas had higher expression along midline structures as compared to the cerebral hemispheres. Our study suggests that topographic location of pediatric diffuse midline gliomas and hemispheric high-grade gliomas correlates with driver mutations of tumor to the endogenous gene expression in that location. This correlation suggests that cellular state that is required for increased gene expression predisposes that location to mutations and defines the driver mutations within tumors that arise from that region.

Correlation Between Immunohistochemistry and Sequencing in H3G34-Mutant Gliomas.

Recurrent glycine-to-arginine/valine alterations at codon 34 (G34R/V) within H3F3A gene characterize a subset of hemispheric high-grade gliomas (HGG) affecting children and young adults. These tumors, defined as G34R/V-mutant gliomas, are histologically heterogenous, with microscopic features of either HGG or embryonal tumors (primitve neuroectodermal tumor-like features). To assess the value of immunohistochemistry (IHC) to detect G34R/V-mutated cases, we tested anti-histone G34V (clone 329E5) and anti-histone G34R (clone RM240) antibodies in a series of 28 formalin-fixed and paraffin-embedded samples. A total of 28 cases of hemispheric, IDH-wt HGG mainly affecting children and young adults were evaluated by IHC and by sequencing. The median age of patients at diagnosis was 17 years (0.1 to 26 y). By IHC, 10 of the 28 cases showed nuclear positivity for G34R and 3 of the 28 cases for G34V. Molecular analysis of G34R/V-mutation status was successful in 24 of the 28 cases. Mutation at glycine 34 of the H3F3A gene was identified in 9 of the 24 tumors (37%) by direct sequencing, revealing 7 of 9 positive case by sequencing and 2 of 9 false negative cases by IHC. Two of 15 negative case by sequencing demonstrated a false positivity by IHC. In total, in 4 (16.6%) of 24 cases, IHC and mutational results were discordant: 2 tumors were negative by IHC (false negative) but harbored G34R mutation by sequencing, and 2 cases were positive by IHC (false positive by IHC) but wild type by sequencing. Moreover, most mutated cases showed loss of ATRX expression and/or p53 expression. The positivity by IHC with specific antibody tested is not highly predictive for presence of G34R/V mutation, but confirmation by sequencing is mandatory; G34R/V mutations should be suspected in all hemispheric tumor IDH1/2 wild type, showing loss of OLIG2 and ATRX and/or p53 expression.

Abstract IA29: Developmental and oncogenic programs in pediatric brain tumors dissected by single-cell RNA-sequencing

Abstract During development, the multiple cell types of human brain arise from pluripotent stem cells via progressively more committed progenitor cells. Emerging data suggest that pediatric brain tumors arise from progenitors that have become developmentally stalled. In preliminary studies, our lab used single-cell RNA-seq to display the expression profiles of individual cells within pediatric midline and hemispheric high-grade gliomas. Our data show that these tumors are composed of (i) replicating cells that resemble glial and neural progenitors and (ii) maturing cells resembling astrocytes, oligodendrocytes, or mesenchymal cells. In this presentation I will address how single-cell RNA-sequencing has revolutionized our understanding of the developmental hierarchy and oncogenic programs in pediatric brain tumors. Our recent findings pointing towards potential cells of origin of midline and hemispheric pediatric high-grade gliomas as well as plasticity of different cancer cell states will be discussed. Citation Format: Mariella G. Filbin. Developmental and oncogenic programs in pediatric brain tumors dissected by single-cell RNA-sequencing [abstract]. In: Proceedings of the AACR Special Conference on the Advances in Pediatric Cancer Research; 2019 Sep 17-20; Montreal, QC, Canada. Philadelphia (PA): AACR; Cancer Res 2020;80(14 Suppl):Abstract nr IA29.

Quantitative longitudinal evaluation of diaschisis-related cerebellar perfusion and diffusion parameters in patients with supratentorial hemispheric high-grade gliomas after surgery.

Decreased cerebral blood volume (CBV) in contralateral cerebellar gray matter (cGM) in conjunction with cerebellar white matter (cWM) damage, consistent with crossed cerebro-cerebellar diaschisis (cCCD) develop following supratentorial hemispheric stroke. In this study, we investigated the longitudinal evolution of diaschisis-related cerebellar perfusion and diffusion tensor-imaging (DTI) changes in patients after surgery for supratentorial brain tumors. Eight patients (M:F 5:3, age 8-22years) who received surgery for supratentorial high-grade gliomas were evaluated. Initial MRI studies were performed 19-54days postoperatively, with follow-ups at 2- to 3-month intervals. For each study, parametric maps of the cerebellum were generated and coregistered to T1-weighted images that had been previously segmented for cGM and cWM. Aggregate mean values of CBV, cerebral blood flow (CBF), and fractional anisotropy (FA) were obtained separately for cGM and cWM, and asymmetry indices (AIs) were calculated. Hemodynamic changes were more robust in cGM than in cWM. Seven patients showed decreased perfusion within cGM contralateral to the supratentorial lesion on the first postoperative study, and asymmetry was significant for both CBV (p = 0.008) and CBF (p < 0.01). For CBV, follow-up studies showed a significant trend towards recovery (p < 0.02). DTI changes were more pronounced in cWM. FA values suggested a "paradoxical" increase at initial follow-up, but steadily declined thereafter (p = 0.0003), without evidence of subsequent recovery. Diaschisis-related hemodynamic alterations within cGM appear on early postoperative studies, but CBV recovers over time. Conversely, cWM DTI changes are delayed and progressive. Although the clinical correlates of cCCD are yet to be elucidated, better understanding of longitudinal structural and hemodynamic changes within brain remote from the area of primary insult could have implications in research and clinical rehabilitative strategies.

Mutations in SETD2 and genes affecting histone H3K36 methylation target hemispheric high-grade gliomas

Recurrent mutations affecting the histone H3.3 residues Lys27 or indirectly Lys36 are frequent drivers of pediatric high-grade gliomas (over 30 % of HGGs). To identify additional driver mutations in HGGs, we investigated a cohort of 60 pediatric HGGs using whole-exome sequencing (WES) and compared them to 543 exomes from non-cancer control samples. We identified mutations in SETD2, a H3K36 trimethyltransferase, in 15 % of pediatric HGGs, a result that was genome-wide significant (FDR = 0.029). Most SETD2 alterations were truncating mutations. Sequencing the gene in this cohort and another validation cohort (123 gliomas from all ages and grades) showed SETD2 mutations to be specific to high-grade tumors affecting 15 % of pediatric HGGs (11/73) and 8 % of adult HGGs (5/65) while no SETD2 mutations were identified in low-grade diffuse gliomas (0/45). Furthermore, SETD2 mutations were mutually exclusive with H3F3A mutations in HGGs (P = 0.0492) while they partly overlapped with IDH1 mutations (4/14), and SETD2-mutant tumors were found exclusively in the cerebral hemispheres (P = 0.0055). SETD2 is the only H3K36 trimethyltransferase in humans, and SETD2-mutant tumors showed a substantial decrease in H3K36me3 levels (P < 0.001), indicating that the mutations are loss-of-function. These data suggest that loss-of-function SETD2 mutations occur in older children and young adults and are specific to HGG of the cerebral cortex, similar to the H3.3 G34R/V and IDH mutations. Taken together, our results suggest that mutations disrupting the histone code at H3K36, including H3.3 G34R/V, IDH1 and/or SETD2 mutations, are central to the genesis of hemispheric HGGs in older children and young adults.Electronic supplementary materialThe online version of this article (doi:10.1007/s00401-013-1095-8) contains supplementary material, which is available to authorized users.

Sparing of the hippocampus, limbic circuit and neural stem cell compartment during partial brain radiotherapy for glioma: A dosimetric feasibility study

The aim of this study was to assess the feasibility of sparing contralateral or bilateral neural stem cell (NSC) compartment, hippocampus and limbic circuit during partial brain radiotherapy (PBRT). Treatment plans were generated for five hemispheric high-grade gliomas, five hemispheric low-grade gliomas and two brainstem gliomas (12 patients). For each, standard intensity-modulated radiotherapy (IMRT) plans were generated, as well as IMRT plans which spared contralateral (hemispheric cases) or bilateral (brainstem cases) limbic circuit, hippocampus, and NSC. Biologically equivalent dose for late effects (BED(late effects)) was generated for limbic circuit, hippocampus and NSC. Per cent relative reduction in mean physical dose and BED was calculated for each plan (standard vs. sparing). We were able to reduce physical dose and BED(late effects) to these critical structures by 23.5-56.8% and 23.6-66%, respectively. It is possible to spare contralateral limbic circuit, NSC and hippocampus during PBRT for both high- and low-grade gliomas using IMRT, and to spare the hippocampus bilaterally during PBRT for brainstem low-grade gliomas. This approach may reduce late cognitive sequelae of cranial radiotherapy.