bluuebunny/crossref_metadata_2025_split huggingface dataset:
HGG-09. MicroRNAs expression profile in Meningioma 1 (MN1) gene altered astroblastoma
Authors: Antonelli Manila , Miele Evelina , Mastronuzzi Angela , Pollo Bianca , Massimino Maura , Gardiman Marina , Buttarelli Francesca , Minasi Simone , Giangaspero Felice , Gianno Francesca 
Published: June 2022

Abstract
Astroblastoma is a rare glial neoplasm arising more frequently in young, predominantly female, patients and with unclear clinical behavior and outcome. The diagnostic molecular alteration is the rearrangement of meningioma 1 (MN1) gene.However, little is known about the specific mechanism of tumor development driven by such genetic change. microRNAs (miRNAs) are important gene expression regulators with strong implications in several biological processes. In this study we investigated the microRNAs’ expression and regulation in MN1 altered neoplasms. We collected a cohort of 14 formalin-fixed, paraffin-embedded (FFPE) tumor samples histologically defined classified as astroblastoma. The DNA methylation analysis showed that only 8 cases harbored the MN1 rearrangement characteristic of astroblastoma. The 8 MN1 altered tumors were analyzed for their expression pattern of miRNAs by Nanostring technology. Thirty-nine deregulated miRNAs were found in the 8 astroblastomas compared to normal brain tissue. In order to understand the underlying mechanisms of the miRNAs aberrant expression, we first investigated the methylation status of themicroRNA promoters. Thirty-two out 39 deregulated miRNA resulted epigenetically regulated. with methylation status coherent with microRNA expression in 14/32 miRNAs.. Secondly, we investigated the hypothesis of a genomic alteration as a reason for the abnormal expression of the remaining 18/32 deregulated miRNAs by analyzing the Copy Number Variation (CNV) of tumor samples. but no alteration was found on miRNAs chromosome loci. Finally, we identified validated targets of the 32 deregulated miRNAs and uncovered biological processes putatively correlated to miRNA target genes, clinically and pathologically relevant in MN1-altered astroblastomas. Our findings shed light on the biology of this rare disease with potential implications on prognostic markers and therapy.
HGG-21. Oncogenic tyrosine kinase gene fusions in infant-type hemispheric gliomas - comparison of RNA- and DNA-based methods for their reliable detection
Authors: Pietsch Torsten , Gielen Gerrit , Waha Andreas , Doerner Evelyn , von Bueren Andre O , Vokuhl Christian , Kristiansen Glen , Kramm Christof 
Published: June 2022

Abstract
High-grade diffuse gliomas (HGG) in early childhood are characterized by a more favorable outcome compared to older children. We demonstrated in previous studies that these tumors have stable genomes. Activating tyrosine kinase gene fusions in infant-type hemispheric gliomas represent therapeutic targets. 50 supratentorial HGG occurring in children younger than four years were retrieved from the archives of the Brain Tumor Reference Center, Institute of Neuropathology, Bonn University. DNA and RNA were extracted from FFPE tumor samples. Gene fusions were identified on the DNA level by FISH using break-apart probes for ALK, NTRK1, -2, -3, ROS1 and MET and Molecular Inversion Probe (MIP) methodology. On the RNA level, fusion transcripts were detected by targeted RNA sequencing as well as Nanostring assay with fusion-specific probes. 37 supratentorial HGG occurred in the first year of life, 13 HGG between one and four years. 18 cases showed fusions of ALK to different partners; all occurred in the first year of life (18/37, 48.6%). Fusions of ROS1 were found in 5, MET in 3, NTRK1, -2, -3 in 10 cases. 12 cases showed no and two cases novel fusions. The different methods led to comparable results. Only recurrent fusions with known fusion partners were detectable with fusion sequence-specific Nanostring probes and library construction for targeted RNA sequencing failed in a fraction of cases. Break-apart FISH led to reliable results on the next day, and MIP technology represented the most sensitive method for analysis of FFPE samples. Gene fusions involving the tyrosine kinase genes ALK, MET, ROS1 and NTRK1, -2, -3 occurred in 72% of HGG of young children; most frequent were ALK fusions occurring in tumors of infants. DNA-based MIP technology represented the most robust and sensitive assay. A combination of RNA- and DNA-based methods to detect these fusions with high reliability is recommended.
HGG-29. How I treat recurrent pediatric high-grade glioma (HGG): A Europe-wide survey study.
Authors: Perwein Thomas , Giese Barbara , Nussbaumer Gunther , von Bueren André O , van Buiren Miriam , Benesch Martin , Kramm Christof Maria 
Published: June 2022

Abstract
PURPOSE: Prognosis of pediatric high-grade gliomas (pedHGG) is dismal, and there is no standard of care treatment in case of recurrence/progression. We aimed to gain an overview of different treatment strategies in the setting of recurrent/progressing pedHGG. METHODS: In a web-based questionnaire, members of the SIOPE-BTG and the GPOH were surveyed on different therapeutic options in four real-world case scenarios (children/adolescents with recurrent/progressing HGG). RESULTS: One hundred and thirty-nine clinicians with experience in pediatric neuro-oncology from 22 European countries participated in the survey. Most respondents preferred further active (multimodal) oncological treatment in three out of four cases and chose palliative care with pure symptom control measures only in one case (gliomatosis cerebri and marked symptoms). Depending on the case, 8-92% of experts would initiate a re-resection (maximal safe resection in case of localized hemispheric pedHGG), combined with molecular diagnostics, and 55-77% recommended (re-)irradiation, preferably local radiotherapy &gt;20 Gy (or craniospinal irradiation in one case with disseminated spinal HGG, 65%). Throughout all case scenarios, most respondents would participate in clinical trials and use targeted therapy (79-99%), depending on molecular genetic findings (BRAF alterations: BRAF/MEK inhibitors, 64-88%; EGFR overexpression: anti-EGFR treatment, 46%; SMARCB1 deletion: EZH2 inhibitor, 12%). 31-72% would administer chemotherapy (CCNU, 17%; PCV, 8%; temozolomide, 19%; oral etoposide/trofosfamide, 8%), and 20-69% advocated immunotherapy (checkpoint inhibitors, 30%; tumor vaccines, 16%). Depending on the individual case, respondents would also include bevacizumab (6-18%), HDAC inhibitors (4-15%), tumor-treating fields (1-26%), and intraventricular chemotherapy (4-24%). CONCLUSIONS: In each case, experts would combine conventional multimodal treatment concepts, including re-irradiation, with targeted therapy based on molecular genetic findings. International cooperative trials combining a standard (chemo-)therapy backbone with targeted therapy approaches for defined subgroups may help to gain valid clinical data and improve treatment in pediatric patients with recurrent/progressive HGG.
HGG-40. NF1 mosaicism in a CMMRD-patient with a glioblastoma
Authors: Guerrini-Rousseau Lea , Cabaret Odile , Muleris Martine , Vidaud Dominique , Cotteret Sophie , Rouleau Etienne , de Beaumais Tiphaine Adam , Varlet Pascale , Morscher Raphael , Abbou Samuel , Dufour Christelle , Brugieres Laurence , Grill Jacques 
Published: June 2022

Abstract
Constitutional Mismatch Repair Deficiency (CMMRD) and Neurofibromatosis type 1 (NF1) are brain tumor predisposing syndromes associated with café-au-lait macules (CALM). Due to this overlap, establishing the differential diagnosis can be difficult, but remains crucial as treatments and surveillance protocols clearly differ for affected patient according to the underlying disease. We reported a girl, with a clinical diagnosis of sporadic NF1 during childhood, who presented a glioblastoma at 16 years-old. Faced with the NF1-like phenotype, diagnosis of CMMRD was suspected because tumor was ultra-hypermutated (228.67 mut/Mb), with a loss of PMS2 expression in both tumor and normal cells. Germline analyses identified a compound heterozygous pathogenic variant (PV) in the PMS2 gene, with an abnormal methylation tolerance test, that confirmed CMMRD. Moreover, a NF1 PV (20% and 9% in blood and saliva samples respectively) was identified compatible with a germline mosaicism. Patient's phenotype was atypical for CMMRD, with a voluminous neurofibroma and ephelids rather observed in NF1. CMMRD oncogenesis is not currently understood, in particular involvement of an NF1 PV, which could arise early from the ultra-hypermutated burden and might explain clinical signs, in particular CALMs. CMMRD diagnosis allowed proposing an adapted genetic counseling and surveillance for the patient and her parents according to the published guidelines due to the major impact on the patient’s oncological risks and prognosis. The best strategy for surveillance of the neurofibroma is still debated due to uncertainties about its risk of degeneration with a CMMRD underlying disease. This observation raises the question of the frequency of mosaic NF1 germline PV in CMMRD-patients and the time of its postzygotic appearance in the context of a biallelic deficit of one of the MMR genes. Combination of these both CMMRD and NF1 germline PVs would be a strong argument for a combination of MEK-inhibitors with immunotherapy.
HGG-44. Unraveling and Targeting the stem-regulatory network driving invasion in Diffuse hemispheric glioma, H3G34-mutant
Authors: Palma Alessandro , Ferretti Roberta , Pericoli Giulia , Pellegrino Marsha , Petrilli Lucia Lisa , Molinari Valeria , Boult Jessica K R , Bierke Lynn , Carai Andrea , Mastronuzzi Angela , Robinson Simon P , Carcaboso Angel Montero , Jones Chris , Locatelli Franco , de Billy Emmanuel , Vinci Maria 
Published: June 2022

Abstract
Diffuse hemispheric glioma H3G34-mutant (DHG-G34) is a pediatric-type high-grade glioma affecting children and young adults. Despite surgery and radio/chemotherapy, patients have a dismal prognosis. The intratumoural heterogeneity and the high infiltrative nature of DHG-G34 cells limit the development of effective therapies. Analysing single-cell RNA sequencing data from a publicly available dataset, we identified a large and distinct sub-population of cells displaying high stem and low differentiation marker expression levels. Gene ontology analyses revealed a gene signature related to cell migration/invasion. This observation is supported by our data on in vitro 3D invasion assay and in vivo orthotopic xenograft models, showing that DHG-G34 disseminating cells are characterised by high expression level of the stem-cell marker NESTIN and low expression level of the differentiation marker GFAP. Following these findings, we developed high-throughput cell-based assays with the aim to screen a library of 1300 FDA-approved compounds and identify drugs able to induce DHG-G34 cell differentiation and inhibit their invasive phenotype. The screen, a co-immunofluorescence assay for NESTIN and GFAP, followed by dose response assays on 3D growth and 3D invasion, led to the identification of 3 FDA-approved drugs, the MEK inhibitor Cobimetinib and 2 HMG-CoA reductase inhibitors, Rosuvastatin and Pitavastatin. These 3 drugs potently induced cell differentiation (decreased Nestin and increased GFAP expression) and inhibited invasion with minimal effect on the proliferation of our DHG-G34 cell line. We are currently extending these findings to additional patient-derived DHG cell lines and we are using these drugs and different omics and imaging technologies to characterize the regulatory networks associated to DHG-G34 stemness, (de)-differentiation and invasiveness. Our work may lead to the identification of new therapeutic approaches for targeting the stem/invasive properties of these aggressive diseases.
HGG-51. Uncovering therapeutic vulnerabilities in mismatch repair-deficient gliomas
Authors: Boynton Adam , Pal Sangita , Johnston Ryan , Currimjee Naomi , Qian Kenin , Touat Mehdi , Persky Nicole , Goodale Amy , Berstler James , Miller Lisa , Guletsky Alex , Ligon Keith L , Beroukhim Rameen , Bandopadhayay Pratiti 
Published: June 2022

Abstract
INTRODUCTION: We have observed that approximately 26% of recurrent gliomas acquire hypermutation following treatment with temozolomide (TMZ). Intriguingly, 91% of these tumors harbor mutations in mismatch repair (MMR) genes. Since MMR deficiency confers resistance to TMZ, strategies to target MMR-deficient gliomas stand to impact many patients. METHODS: We ablated the MMR genes MSH2, MSH6, MLH1, and PMS2 using an all-in-one sgRNA-CRISPR/Cas9 expression vector to generate isogenic MMR knockouts in patient-derived glioma cell lines. We characterized the gene expression profiles of these MMR-deficient glioma models and leveraged high-throughput drug screens and genome-scale CRISPR/Cas9 dropout screens to identify therapeutic vulnerabilities induced by loss of MMR. RESULTS: We show that loss of each major MMR gene confers resistance to TMZ. Gene set enrichment analysis of our MMR-deficient knockouts shows enrichment of several hallmark gene sets including DNA repair and G2M checkpoint signatures, and our genome-wide CRISPR dropout screen reveals that MMR-deficient cells are preferentially dependent on a number of genes involved in DNA repair and cell cycle, along with several other pathways. Lastly, the high-throughput drug repurposing (REPO) screen shows that loss of MMR confers differential dependencies to small molecule inhibitors. CONCLUSIONS: Using CRISPR/Cas9 to knock out individual MMR pathway members allows us to systematically study the response of MMR-deficient cells to alkylating agents in an isogenic context. Importantly, these isogenic models reveal that MMR-deficient glioma cells possess novel genetic dependencies and sensitivities to small molecules, which may inform future therapies for MMR-deficient tumors.
HGG-62. Molecularly guided treatment of mismatch repair-deficient pediatric brain tumors
Authors: Crotty Erin , Cole Bonnie , Stasi Shannon , Vitanza Nicholas , Paulson Vera , Lockwood Christina , Leary Sarah 
Published: June 2022

Abstract
Mismatch repair (MMR)-deficient brain tumors, defined by high tumor mutational burden (TMB) and alterations in MMR or DNA proofreading genes, may harbor therapeutic vulnerabilities to immune checkpoint inhibition (ICI) and resistance to temozolomide. We report a single-institution experience incorporating a personalized genomics approach for pediatric brain tumor patients with high TMB. Tumor and peripheral blood samples were obtained at surgery or autopsy and molecular profiling performed by UWOncoPlex, a multiplexed DNA sequencing panel. Treatment and survival information was obtained by medical records review. Tumor types included high-grade glioma (10, including 1 DIPG), and desmoplastic/nodular medulloblastoma (1). Metachronous tumors were present in three patients and median age at diagnosis was 11.5 years (range 8 – 18). Constitutional predisposition included MMR deficiency (CMMRD), Lynch syndrome, and polymerase proofreading deficiency (PPD). All patients had localized disease, with gross total resection achieved in 6/11 (55%). All received radiation (RT), with concurrent temozolomide delivered in HGG (9). 7/9 patients (78%) with HGG had radiographic progression following RT/temozolomide. Five patients received ICI with pembrolizumab (4), nivolumab/ipilimumab (2), or nivolumab alone (1). Two patients progressed on pembrolizumab then had partial responses to dual nivolumab/ipilimumab. Another patient had a complete response to pembrolizumab and remains disease-free nearly 1 year after discontinuing drug due to reactivated skin GHVD. While not statistically significant in this small cohort, median survival of ICI-treated patients (5) compared to those who received alternative therapies (6) was 40.4 vs. 17.7 months. Patients with durable responses &gt;18 months to ICI (3) included one who underwent surgical debulking following nivolumab, and two patients molecularly classified as CMMRD + somatic PPD. This series highlights the importance of integrating molecular findings and identification of high TMB early in clinical diagnosis and supports the use of ICI to achieve durable responses in children with MMR-deficient brain tumors.
IMG-01. Quantitative Direct Sodium (23Na) MRI in Pediatric Gliomas
Authors: Bhatia Aashim 
Published: June 2022

Abstract
BACKGROUND: The treatment of pediatric gliomas is typically assessed with proton (1H) MRI, which can have limitations. 23Na MRI has been shown in adult brain tumors to measure intra-tumoral total sodium concentration as a correlate of tumor proliferation. 23Na MRI sodium studies in pediatric patients are lacking. PURPOSE: (1) To compare total sodium concentration (TSC) between pediatric glioma and non-neoplastic brain tissue using 23Na MRI; (2) Compare tissue conspicuity of bound sodium concentration (BSC) using 23Na MRI dual echo relative to TSC imaging. MATERIALS AND METHODS: TSC was measured in: (1) non-neoplastic brain tissues and (2) three types of manually segmented gliomas [diffuse intrinsic brainstem glioma (DIPG), recurrent supratentorial low-grade glioma (LGG), and high-grade glioma (HGG)] on sodium MRI images co-registered with proton MRI. In a subset of patients, serial changes in both TSC and BSC (dual echo 23Na MRI) were assessed for tissue conspicuity using voxel-based parametric maps. RESULTS: Twenty-six pediatric patients with gliomas (median age of 12.0 years, range 4.9 – 23.3 years) were scanned with 23Na MRI. Uninvolved tissues demonstrated a range of TSC values similar to published adult values. DIPG treated with RT demonstrated higher TSC values than the uninvolved infratentorial tissues (P&lt;0.001). Recurrent supratentorial LGG and HGG exhibited higher TSC values than the uninvolved white matter (WM) and gray matter (GM) (P&lt;0.002 for LGG, and P&lt;0.02 for HGG). The dual echo 23Na MRI suppresses the sodium signal within both CSF and necrotic foci, resulting in improved conspicuity of both non-neoplastic and neoplastic, compared to serial TSC imaging. CONCLUSION: Quantitative 23Na MRI of pediatric gliomas demonstrates a range of values that are higher than non-neoplastic tissues. Dual echo 23Na MRI of BCS improves tissue conspicuity relative to TSC imaging. Future studies are needed to determine the value of 23Na MRI in delineating therapeutic responses in pediatric gliomas.
IMMU-06. Landscape of adaptive immunity of childhood brain cancers
Authors: Raphael Itay , Chikina Maria , Broniscer Alberto , Pollack Ian , Rajasundaram Dhivyaa , Kohanbash Gary 
Published: June 2022

Abstract
T lymphocytes have a unique ability to recognize a vast array of antigens prompted by an enormous T cell receptor (TCR) repertoire. Characterization of tumor-infiltrating T cells (TILs) is key to understand MHC-restricted anti-tumor immunity and for developing T cell-centered immunotherapies such as adoptive cell therapy and tumor vaccines. In the current work, we investigated RNA-Seq data from 997 pediatric brain tumor patients and performed a large-scale comprehensive examination of the immunogenomic and TCR landscape of TILs across the entire spectrum of pediatric brain tumors. We show that the relative ratio between T cell diversity (clonality) and T cell abundance within each sample, represented by the clonal expansion index (CEI), is a strong predictor of prognosis both within and between tumor types. Interestingly, we show that CEI was strongly associated with molecular subgroups of medulloblastoma but not with known tumor-genomic features of these subgroups. Investigation of TCR clones recognizing a common recurrent tumor-antigen across patients based on CDR3 homology and characteristics, reveals 9 TCR clusters which are tumor type restricted with defined prognoses and HLA dominance. Using computational immunogenomics and machine learning-based investigations of these clusters yielded novel putative HLA-restricted tumor antigens which could bind and activate the clusters’ specific TCRs. Importantly, our framework grounded the foundations for developing a precision medicine approach of T cell-centered immunotherapies. These findings have major implications for understanding the interplay between T cell and tumor genomic, and for developing new immunotherapies for children with brain tumors.
IMMU-07. Interim analysis of the HIT-HGG Rez Immunvac study - Dendritic cell vaccination with partial Treg depletion and double checkpoint blockade in children with relapsed high-grade gliomas.
Authors: Eyrich Matthias , Krauss Jürgen , Ghaffari Maryam , Caruana Ignazio , Rachor Johannes , Monoranu Camelia-Maria , Bison Brigitte , Rückriegel Stefan , Wölfl Matthias , Miller Elisabeth , Schlegel Paul-Gerhardt , Kramm Christof 
Published: June 2022

Abstract
Relapses of high-grade gliomas show an aggressive course and survival 6 months after (sub-)total re-resection was only 62% in former HIT-HGG trials. Immunotherapy by induction of tumor-specific T cells through active immunization might help to control glioma regrowth. In the HIT-HGG-Rez Immunovac trial (Eudra-CT 2013-000419-26) we investigate whether a therapeutic vaccine (autologous dendritic cells loaded with tumor lysate, DCV) combined with Treg-depletion and double checkpoint-inhibition (CI, anti-PD-1/anti-CTLA4) is able to increase the number of patients alive 6 months after relapse. Here, we report interim results after 50% of the intended patients (n=25) have been recruited. 13 children and adolescents (mean age 12.7±4.0 y) with relapsed glioblastomas were screened for the trial so far. Three patients were screening failures, 10 patients received study treatment. Of these, 2 patients are currently vaccinated, so that 8 patients were evaluable for this interim analysis. 5 SAEs have been reported so far, none of them was limiting. 4 patients with gross total or subtotal resection at time of relapse had an overall survival (OS) of 13.2±4.0 months and a 6-month survival rate of 100%, which compares favourably to historical controls. 4 partially resected patients survived only 5.1±1.3 months and 6-months OS was 25%. Treg-depletion lead to a reduction of CD4+CD127-CD25+ T-cells of 45%, the majority of patients exhibited a tumor-specific T-cell response. We conclude that DCV in combination with partial Treg-depletion and CI is feasible, safe, and related with immunological responses. Double CI was not associated with unexpected toxicities. In (sub-)totally resected patients, immunotherapy seems to confer a survival advantage. For the completion of the trial we aim to include more patients with (sub-)totally resectable tumors to gain more insight into the nature and duration of the induced immune response. This trial is supported by Bristol Myers-Squibb (CA209-7JA).