bluuebunny/crossref_metadata_2025_split huggingface dataset:
HGG-45. Characterization of spinal diffuse midline gliomas, H3 K28M-mutant
Authors: Stegat Lotte , Thomas Christian , Schweizer Leonille , Neyazi Sina , Pohl Lara , Frank Stephan , Dorostkar Mario M , Schüller Ulrich , Wefers Annika K 
Published: June 2022

Abstract
Diffuse midline gliomas (DMGs) are malignant gliomas that arise in the midline structures of the central nervous system. Due to their aggressive and diffuse growth and a two-year survival rate of less than 10%, DMGs are assigned to CNS WHO grade 4. Depending on the localization, median age of patients is about 11‒20 years. Genetically, most tumors are defined by a K28M-mutation in one of the highly homologous genes encoding histone protein H3. Since DMGs most frequently occur in pons and thalamus, comparatively little is known about spinal DMGs. Therefore, we histologically, molecularly, and clinically characterized spinal DMGs and analyzed, in which aspects they differ from DMGs of other localizations. Our cohort currently consists of 25 spinal DMGs and 40 pontine/thalamic reference cases. Histological, immunohistochemical and molecular analyses (DNA methylation, DNA panel sequencing) were done from FFPE tissue. Spinal DMGs were histologically very heterogeneous, both regarding different areas of single tumors as well as in comparison to other spinal and reference cases. First cluster analyses of DNA methylation data indicated a separation into three main clusters enriched for pontine, thalamic or spinal cases. The cluster enriched for spinal cases contained many tumors from elderly patients. Overall, mean age of patients with spinal DMGs was 28 years. Patients were significantly older than those with pontine DMGs. 19/20 spinal DMGs were H3-3A K28M-mutant, while one tumor had an H3-2B mutation. 4/19 (21%) spinal DMGs had mutations in FGFR1, and 6/10 (60%) in NF1. Three tumors had KRAS or BRAF mutations. In summary, first analyses suggest slight histological differences of spinal DMGs compared to DMGs of other localizations. Preliminary cluster analyses of DNA methylation data showed an enrichment of clusters for different localizations. About one third of spinal DMGs had mutations in a gene associated with the MAPK-signaling pathway.
HGG-46. Inter and Intra-tumor Heterogeneity of Pediatric-type Diffuse High-Grade Glioma Revealed by High-Dimensional Single-Cell Proteomics
Authors: Petrilli Lucia Lisa , Fuoco Claudia , Pasquini Luca , Palma Alessandro , Pericoli Giulia , Grabovska Yura , Mackay Alan , Rossi Sabrina , Camassei Francesca Diomedi , Carcaboso Angel Montero , Carai Andrea , Mastronuzzi Angela , Jones Chris , Cesareni Gianni , Locatelli Franco , Vinci Maria 
Published: June 2022

Abstract
Paediatric-type diffuse high-grade gliomas (PDHGG) are aggressive brain tumors, affecting children and young adults, with no effective treatments. A main constraint to the development of effective treatment is associated with their highly heterogeneous nature. In order to further dissect their intra and inter tumor heterogeneity, we exploited the mass cytometry technology, an advanced -OMIC approach that, by using metal-tagged antibodies, allows the simultaneous measurement of more than 40 markers, at single-cell level. Here we characterized 8 primary cell lines derived from diffuse pediatric-type high-grade glioma H3-wildtype (DHGG-WT), Diffuse hemispheric glioma H3G34-mutant (DHG-G34) and Diffuse midline glioma H3K27-altered (DMG-K27) patients. The adopted antibody panel was set to recognize antigens expressed by brain and tumor cells, including H3K27M and H3.3G34R variants, and it highlighted important intra- and inter- tumor heterogeneity in the expression of the 16 considered markers. Of these, CD56, CD44, CD29 and NESTIN were more expressed in the hemispheric cell lines, while CD90 was more expressed in the pontine. Even if there was not always a concordance between CyTOF and mRNA expression data from cell lines and tumor samples (e.g. CD90 and GFAP), CyTOF data were in line with the immunohistochemistry analysis for GFAP, whose expression was significantly higher in H3.1K27 compared to H3.3K27. The UMAP analysis allowed us to identify 10 cell clusters, with very minimal overlap between hemispheric and pontine location subgroups and with a peculiar antigenic profile, whose abundance strongly varied according to the mutational subgroups. For example, while the G34 subgroup was enriched for cluster 9 (CD29/CD63/CD56/PDGRFa), the H3.1K27 was enriched for cluster 3 (H3K27M/CD90/CD63/CD56) and cluster 4 (H3K27M/CD63/CD90/CD56/GFAP). In conclusion, single-cell mass cytometry reveals a significant inter and intra-tumoral heterogeneity at protein level, dependent on the molecular alterations. This approach could contribute to the identification of new clinically relevant biomarkers for PDHGG.
HGG-48. A comparative proteomic analysis of the cell membrane of histone 3 mutated paediatric high-grade gliomas in order to identify potential immunotherapeutic targets
Authors: Suresh Sneha , Khan Alina , Snary Anya , Pickering James , Rahman Ruman , Grundy Richard , Layfield Robert , Haque Farhana 
Published: June 2022

Abstract
Improvements in the treatments for childhood and adolescent brain tumours, High-Grade Glioma (pHGG) and Diffuse Intrinsic Pontine Glioblastoma (DIPG), have not advanced much and they continue to carry a very poor prognosis. These brain tumours are now defined by mutations affecting histone 3 proteins, indeed 80% of DIPGs harbour histone H3.1 and H3.3 K27M somatic mutations whilst 30% of pHGGs exhibit H3.3 G34R or G34V mutations. We hypothesized that the histone 3 mutant tumours will have distinct mutation specific surfactome or cell surface proteins. We therefore analysed the cell surface proteomics of H3.3 G34V and G34R mutated high-grade glioma in comparison to the H3 wild-type Glioma, to explore whether these proteins have the potential to be used as immunotherapeutic targets. We have at first isolated the cell membrane fractions from a range of patient cells carrying histone 3 mutations (G34R, G34V) relative to wild type histone 3. A comparative quantitative liquid chromatographic mass-spectrometry analyses of these cell surface membrane fractions were performed to identify specific targetable factors. The results of these were analysed with the focus in identifying proteins that can be targeted for tumour specific immune modulation or immunotherapeutic intervention. Results of these analyses will be presented.
HGG-52. Combinatorial modulation of hypoxic pathways leads to anti-tumoral effects in H3.3 K27M midline gliomas
Authors: Fuchs Quentin , Lhermitte Benoit , Foppolo Sophie , Hubsch Clemence , Martin Sophie , Dontenwill Monique , Entz-Werlé Natacha 
Published: June 2022

Abstract
Pediatric midline high-grade gliomas (pmHGG) are aggressive and incurable tumors of the central nervous system. There is a pressing need for novel therapeutic approaches to treat them. Therefore, proactive translational studies wish to go further discovering new targetable proteins and pathways. Our objectives are then to focus on the modulation of microenvironmental extrinsic features like intra-tumor hypoxia. To do so, we looked first on expressions of hypoxia biomarkers in a pool of patient-derived preclinical models of pmHGG and tested oxygen modulations, as well as hypoxia drug targeting. We designed subsequently our work in those models H3.3 mutated to evaluate balance between HIF1 and HIF2 expressions (immunofluorescence, RTqPCR, RNAseq and metabolomics) and to evidence the impact of hypoxia targeting combined to irradiation on cell proliferation, migration and metabolism. Hypoxia is inducing mainly HIF1 expression and its upstream and downstream pathways and is stabilizing HIF2 expression. Both HIFs are part of crucial survival signaling and represent targets to combine with irradiation. The use of their specific inhibitors shows an antiproliferative effect when HIF1 is downregulated. HIF2 inhibitors are stopping HIF2 transcriptional effect letting us uncover new pathways that this hypoxic inducible factor is regulating in pmHGG (stemness, glycolytic and aminoacid metabolism and histone expression). Together with irradiation this anti-hypoxic strategy seems to be highly effective on cell arrest and migration. Those results are confirming central roles of HIFs in pmHGG and their potencies in pmHGG therapies. The therapeutic efficiency is independent from p53 abnormalities in our models.
HGG-57. Barriers in the management of pediatric high-grade gliomas in a low-resource setting during the COVID era
Authors: Manigos Kirby , Malilay Oliver Ryan , Navarro Joseph Erroll , Seng Kenny , Alcazaren Jose Carlos , Golditum Jared Paul , Baticulon Ronnie 
Published: June 2022

Abstract
INTRODUCTION: High-grade gliomas account for &lt;5% of all pediatric brain tumors with a 20% 5-year overall survival even with maximal safe resection followed by concurrent radiotherapy and chemotherapy. Patients in low- and middle-income countries already face delays and barriers to the treatment they require. The current COVID pandemic has added unique challenges to the delivery of complex, multidisciplinary health services to these patients. METHODOLOGY AND RESULTS: We retrospectively reviewed the records of four patients, ages 2-18 years old, with histologically confirmed high-grade glioma managed in a tertiary government institution from 2020-2021. Three of the patients had a supratentorial tumor and one patient had multiple tumors located in both supra- and infratentorial compartments. Neurosurgical procedures performed were: gross total excision (1), subtotal excision (2), and biopsy (1). The tissue diagnoses obtained were glioblastoma (3) and high-grade astrocytoma (1). Two patients survived and are currently undergoing adjuvant radiotherapy and chemotherapy. The remaining two patients expired: one from hospital-acquired pneumonia and the other from COVID-19 infection. DISCUSSION: Decreased mobility due to lockdowns, the burden of requiring negative COVID-19 results before admission for surgery, reduced hospital capacity to comply with physical distancing measures, the postponement of elective surgery to minimize COVID-19 transmission, physician and nursing shortages due to infection or mandatory isolation of staff, cancellation of face-to-face outpatient clinics, and hesitation among patients and their families to go to the hospital for fear of exposure were found to be common causes of delays in treatment. Also, the redirection of health resources and other government and hospital policies to handle the COVID-19 pandemic resulted in an overall delay in the delivery of health services. In particular, the management of pediatric patients with cancers, especially high-grade gliomas, was significantly disrupted.
HGG-60. Structural variants shape driver combinations and outcomes in pediatric high-grade glioma
Authors: Dubois Frank , Shapira Ofer , Greenwald Noah , Zack Travis , Wala Jeremiah , Tsai Jessica , Crane Alexander , Baguette Audrey , Hadjadj Djihad , Harutyunyan Ashot , Kumar Kiran , Blattner-Johnson Mirjam , Vogelzang Jayne , Sousa Cecilia , Kang Kyung Shin , Sinai Claire , Wang Dayle , Khadka Prasidda , Malkin Hayley , Ho Patricia , O'Rourke Ryan , Zhang Shu , Gold Rose , Deng Davy , Serrano Jonathan , Snuderl Matija , Jones Chris , Wright Karen , Chi Susan , Grill Jacques , Kleinman Claudia , Goumnerova Liliana , Jabado Nada , Jones David , Kieran Mark , Ligon Keith , Beroukhim Rameen , Bandopadhayay Pratiti 
Published: June 2022

Abstract
Pediatric high-grade gliomas (pHGGs), encompassing hemispheric and diffuse midline gliomas (DMGs), remain a devastating disease. The last decade has revealed oncogenic drivers including single nucleotide variants (SNVs) in histones. However, the contribution of structural variants (SVs) to gliomagenesis has not been systematically explored due to limitations in early SV analysis approaches. Using SV algorithms, we recently created, we analyzed SVs in whole-genome sequences of 179 pHGGs including a novel cohort of treatment naïve samples–the largest WGS cohort assembled in adult or pediatric glioma. The most recurrent SVs targeted MYC isoforms and receptor tyrosine kinases, including a novel SV amplifying a MYC enhancer in the lncRNA CCDC26 in 12% of DMGs and revealing a more central role for MYC in these cancers than previously known. Applying de novo SV signature discovery, we identified five signatures including three (SVsig1-3) involving primarily simple SVs, and two (SVsig4-5) involving complex, clustered SVs. These SV signatures associated with genetic variants that differed from what was observed for SV signatures in other cancers, suggesting different links to underlying biology. Tumors with simple SV signatures were TP53 wild-type but were enriched with alterations in TP53 pathway members PPM1D and MDM4. Complex signatures were associated with direct aberrations in TP53, CDKN2A, and RB1 early in tumor evolution, and with extrachromosomal amplicons that likely occurred later. All pHGGs exhibited at least one simple SV signature but complex SV signatures were primarily restricted to subsets of H3.3K27M DMGs and hemispheric pHGGs. Importantly, DMGs with the complex SV signatures SVsig4-5 were associated with shorter overall survival independent of histone type and TP53 status. These data inform the role and impact of SVs in gliomagenesis and mechanisms that shape them.
IMG-05 Imaging characteristics of CNS NB-FOXR2 – a retrospective and MULTI-INSTITUTIONAL DESCRIPTION OF 25 CASES
Authors: Tietze Anna , Lequin Maarten H , Bison Brigitte , Ivarsson Liz , Mirsky David , Jaju Alok , Löbel Ulrike , von Hoff Katja , Mankad Kshitij 
Published: June 2022

Abstract
BACKGROUND: The CNS neuroblastoma with forkhead box R2 (CNS NB-FOXR2) activation is one of the new embryonal tumor entities in the WHO CNS tumor classification 2021. The data currently available suggest a comparably favourable outcome after craniospinal irradiation and chemotherapy. The entity is poorly characterized on imaging. We therefore aimed to describe imaging features in a multi-center patient cohort. MATERIAL AND METHODS: Molecularly and histologically confirmed CNS NB-FOXR2 tumors were retrospectively collected at six pediatric oncology centers. The imaging features on preoperative MRI and CT data were recorded by 8 experienced pediatric (neuro)radiologists in consensus. RESULTS: Twenty-five patients were identified (13 females). The majority of tumors were large at presentation (mean 115 ± SD 83 ml), showed mostly none or little perifocal edema, enhanced only partly, were often calcified and/or hemorrhagic, were always T2w hyperintense to gray matter, and often had cystic and/or necrotic components. The min. mean ADC values were relatively low (mean 687.8 ± SD 136.3 in 10-6mm2/s). The tumors originated never infratentorial and were never centered in the midline. Metastases were rare. CONCLUSIONS: For the first time, imaging characteristics of the recently described CNS NB-FOXR2 are described in a multi-center cohort. The results of this study may assist in diagnosing these tumors preoperatively. Collaborative pooling of cases is important to gain insight into typical imaging features of rare tumors, especially in view of the increasing molecular-driven subtyping.
IMG-09. Characterisation of a panel ofin vivo models of paediatric-type diffuse high-grade glioma (PDHGG) using magnetic resonance imaging
Authors: Boult Jessica , Carvalho Diana , Kessler Ketty , Vinci Maria , Fernandez Elisabet , Bjerke Lynn , Fofana Mariama , Molinari Valeria , Carcaboso Angel , Jones Chris , Robinson Simon 
Published: June 2022

Abstract
Novel therapies for paediatric-type diffuse high-grade glioma (PDHGG) are urgently required. Orthotopic models using patient-derived material are invaluable tools in preclinical drug development as they retain key genetic/epigenetic features, eg. histone H3G34 or H3K27 alterations. Their evaluation in situ is vital and requires sensitive imaging techniques such as MRI. 12 diffuse hemispheric glioma (DHG; 2 DHG-G34) and 21 diffuse midline glioma (DMG; 17 DMG-K27M) tumours have been characterised using MRI following site-specific orthotopic implantation of patient-derived cells directly from tumour material or after minimal expansion as stem cell cultures. Of the 62 models implanted; 3 DHG and 10 DMG samples were not tumourigenic and 13 DHG/3 DMG models are currently under MRI surveillance. Tumours identified on T2-weighted (T2w)-images varied from a diffuse hyperintense signal to well-defined high contrast masses. Tumour growth in 5 DMG models was too diffuse for longitudinal monitoring with T2w-MRI. Once established, diffusion-weighted, T1/T2 mapping and contrast-enhanced MRI were used to further assess tumour phenotype. Quantitative data from 15 DMG models demonstrated higher water diffusivity and T2 than 10 DHG tumours, which suggests less tightly packed tumour cells but may also reflect the closer proximity of tumours growing in the thalamus/pons/cerebellum to the ventricular system. Lack of contrast-agent enhancement in 11 DMG and 6/10 DHG models indicated an intact blood-brain barrier (BBB), with heterogeneous disruption observed in 4 DHGs; H3-G34 had no bearing on BBB integrity. Upon serial re-implantation survival was shortened in 3/4 DHG and 2/6 DMG models, while quantitative MRI parameters remained similar. Likewise, when 2 DHG and 2 DMG models grown in 2D/3D in vitro were implanted in parallel, poorer survival/improved penetrance was associated with 3D-cultured cells with no difference in imaging phenotype. The study highlights the potential of non-invasive MRI to accurately evaluate the efficacy of novel therapeutics in these PDHGG models.
IMMU-01. Combining CD28 and 4-1BB costimulationin trans enhances the anti-glioma efficacy and persistence of B7-H3 CAR T cells in immune-competent brain tumor models
Authors: Haydar Dalia , Elayan Abdul , Yi Zhongzhen , Gottschalk Stephen , DeRenzo Chris , Krenciute Giedre 
Published: June 2022

Abstract
We and others have demonstrated that B7-H3 CAR T-cells have potent antitumor responses in xenograft models for brain tumors; however, these models do not recapitulate the immunosuppressive tumor microenvironment (TME) in patients with high-grade glioma. To evaluate the safety and efficacy of antigen-specific CAR T-cells, we adapted the immune-competent GL261 glioma model which recapitulates human disease and host immune barriers. We generated a library of B7-H3 CARs with different transmembrane (CD8, CD28), costimulatory (CD28, 4-1BB), and activation (ζ, mutζ) domains. We then compared their cytolytic activity, expansion, and anti-tumor activity. Results show that B7-H3 CARs with CD28 transmembrane and costimulatory domains have superior efficacy compared to CARs with CD8 and 4-1BB domains. Additionally, CARs with mutated ζ activation domain have better overall persistence. However, providing costimulation signals through CD28 or 4-1BB alone does not induce superior anti-glioma efficacy of B7-H3 CAR T-cells in vivo. Thus, we next investigated whether incorporating 4-1BB signaling into CD28-based CARs using in trans design enhances the therapeutic efficacy of B7-H3 CAR T-cells. We found that in repeat stimulation assays, surface expression of 4-1BBL enhanced expansion of B7H3 CAR T-cells at least 300-folds more than T-cells with CD28 or 4-1BB costimulatory domains alone. Additionally, 4-1BBL expression significantly enhanced the sequential killing capacity compared to CD28- or 41BB-based B7-H3 CAR T-cells. High dimensional flow cytometry analysis of GL261 tumors post CAR T-cell injection revealed unique immune clusters including dendritic cells and lymphoid predominant populations in mice treated with 4-1BBL expressing CARs. Thus, expression of 4-1BBL on CD28-based CARs reshaped the TME and enhanced persistence and anti-glioma efficacy of B7-H3 CAR T-cells. Studies examining transcriptional and epigenetic programs, and TME/CAR T-cell interactions are in progress. Results will define pathways that dictate CAR T-cell performance and will identify unique mechanisms for further improvements utilizing other members of TNF-superfamily.
IMMU-05. Integrative transcriptomic analysis of pilocytic astrocytomas reveals CNS region-associated characteristics
Authors: Rozowsky Jacob S , Kranendonk Mariëtte E G , van Meeteren Antoinette Y N Schouten- , Meijer Lisethe , Hoving Eelco W , Calkoen Friso G , Wesseling Pieter , Kester Lennart A , van der Lugt Jasper 
Published: June 2022

Abstract
BACKGROUND: Recent insights highlight how the initiation and growth of gliomas is governed by interactions between glioma stem-like cells and stromal and immune cells in the tumor microenvironment. For pilocytic astrocytomas, the most common pediatric CNS tumor, this relationship is so far less explored. To this end, we used transcriptomic methods to investigate inter-patient heterogeneity, and the stromal and immune microenvironment of pilocytic astrocytomas. MATERIALS AND METHODS: In this study, we collected clinical data and tissue of 90 pre-treatment pilocytic astrocytomas from different CNS compartments: posterior fossa (n=57), supratentorial (n=23), and spinal (n=10). The median age at primary resection was 8 (0-16) years, and 66% (n=59) of our cohort was male. From 10 of these patients, we collected post-treatment samples after re-growth of the tumor as well. We characterized all samples by bulk RNA-sequencing and DNA methylation profiling, and selected a subset (n=10) samples for single-nucleus RNA-sequencing. RESULTS: Principal component analysis and unsupervised clustering of bulk sequencing data revealed gene expression patterns correlating to the CNS location of the tumor, consistent with prior reports. Using differential expression and functional pathway analysis, we found CNS region-associated enrichment of cell-cycle, developmental, and inflammatory-related pathways. With respect to the glioma immune microenvironment, supratentorial tumors were enriched in gene-sets related to T-cell activation and cytotoxicity, while spinal tumors had lowest expression of immune-related genes. Moreover, spinal tumors were enriched in pathways related to cell division, nucleotide synthesis, and neurodevelopment. To resolve cell-type expression programs of glioma and immune cells in the microenvironment, we collected and analyzed snRNA-seq data of 10 pilocytic astrocytomas, as well as harmonized our findings with a pre-existing dataset from Vladoiu, 2019. CONCLUSION: Our integrative transcriptomic analysis of pilocytic astrocytomas highlights CNS region-associated differences in expression programs of the glioma cells and in the immune cell composition of the tumor microenvironment.