bluuebunny/crossref_metadata_2025_split huggingface dataset:
EPEN-09. SUPER ENHANCER GENES AS MOLECULAR TARGETS IN C11ORF95-RELA FUSION EPENDYMOMA
Authors: Bertrand Kelsey , Mack Stephen 
Published: June 2021

Abstract
Genomic sequencing has driven precision-based oncology therapy; however, genetic drivers remain unknown or non-targetable for many malignancies, demanding alternative approaches to identify therapeutic leads. Ependymomas comprise histologically similar tumor entities driven by distinct molecular mechanisms, such as fusion oncoproteins, genome-wide chromosomal instability, or disruption of DNA methylation patterns. Despite these differences, ependymomas resist chemotherapy and lack available targeted agents for clinical trial development. Based on our previous findings, we hypothesized that mapping chromatin landscapes and super enhancers (SE) could uncover transcriptional dependencies as targets for therapy (Mack, Pajtler, Chavez et al., Nature, 2018). To functionally test the requirement of these SE genes for ependymoma cellular growth, we designed a pooled RNA interference screen against 267 SE associated genes. Our screen was performed in one C11ORF95-RELA-fusion model and two PF-EPN-A models as controls in biological triplicates. As an indication that our screen was successful, positive controls scored among lead hits including KIF11, BUB1B, PHF5A and MYC. Importantly, we identified many subtype specific dependencies in both C11ORF95-RELA-fusion and PF-EPN-A models, thus revealing novel pathways that potentially govern subgroup-specific ependymoma cell growth. Further, several candidates detected across all ependymoma lines were also identified as pan-cancer dependencies or glioma/glioblastoma specific essential genes from the DepMap Cancer Dependency Gene Resource. Our findings reveal novel targets and pathways that are essential for ependymoma cell growth, which may provide new insight into therapeutic strategies against these aggressive brain tumors.
EPEN-10. UNRAVELLING THE TUMOR IMMUNE MICROENVIRONMENT OF POSTERIOR FOSSA A EPENDYMOMAS ON RNA AND PROTEIN EXPRESSION LEVELS
Authors: F. Feenstra Fenna , Calkoen Friso , Kros Johan M , Kester Lennart , Kranendonk Mariëtte , van der Lugt Jasper , Mustafa Dana A M 
Published: June 2021

Abstract

Background
Ependymomas account for 8–10% of pediatric brain tumors, and the standard therapy of surgery and radiation has not changed for the past two decades. Characterization of the tumor immune microenvironment (TIME) is of great importance in order to find better therapies. However, the TIME of ependymomas is still not defined. In this retrospective observational study we aimed to unravel the TIME of ependymomas at mRNA and protein expression levels.

Methods
Ependymoma samples from two locations were selected: Posterior Fossa (PF-A, n=8), and supratentorial (ST, n=5). Targeted gene expression profile using the PanCancer immune profile panel of NanoString technology was performed. Data were analyzed using the nSolver software. In addition, 8 samples were subjected to RNA bulk sequencing, and the sequenced data were connected to the expression data of the same samples. To validate some of the findings, immunohistochemistry was performed.

Results
Unsupervised hierarchical clustering showed that PF-A ependymomas can be divided into two groups based on the expression of their immune-related genes. PF-A that showed high immune-expression clustered closely to the ST ependymomas. Significant expressions of genes related to “antigen-processing” and “adhesion” pathways were found in the immune-active groups. On the contrary, the PF-A that had low expressions of immune-related genes showed a high expression of BMI1 that has a prognostic and therapeutic value. Connecting gene expression to bulk sequence data validated the findings. In addition, immunohistochemical analysis confirmed that protein expression for some of the findings.

Conclusion
The TIME varies in ependymomas based on the location of the tumor. Moreover, the immune-related expression profiles indicated that PF-A ependymomas can be divided into two groups: immune-active and immune-not active PF-A. The prognostic and therapeutic values of the immune activity of PF-A should be further studied.
GERM-03. CLINICAL FEATURES AND OUTCOME OF CHILDREN WITH INTRACRANIAL NON-GERMINOMATOUS GERM CELL TUMORS: A POPULATION-BASED STUDY IN HONG KONG
Authors: P.Y. Liu Anthony , Ku Dennis T L , Fu Eric , Luk Chung-Wing , Yau Jeffrey P W , Ling Siu-Cheung , Chan Godfrey C F , Shing Matthew M K 
Published: June 2021

Abstract
The incidence of central nervous system non-germinomatous germ cell tumor (NGGCT) is four times higher in Chinese children than in the Western population. Reports on the outcome of Asian patients are nonetheless limited. Here we aim to summarize the experience of treating pediatric NGGCT in Hong Kong. Leveraging a population-wide pediatric oncology database, Chinese children with NGGCT diagnosed from 2002–2020 (n=43) were retrospectively studied. The diagnoses of NGGCT were made either with elevation in tumor markers (AFP/hCG; n=19), or by histology with/without concomitant raise in tumor markers (n=24). Most patients were treated with a combination of chemotherapy (cisplatin/etoposide/bleomycin, carboplatin/etoposide or carboplatin/etoposide/ifosfamide) and radiation (craniospinal+boost, whole ventricular+boost, or focal). The male:female ratio was 37:6, and the median age of diagnosis was 11.2 years. Primary tumor locations were pineal in 18, sellar/suprasellar in 12, basal ganglial in 9, supratentorial in 3 and posterior fossa in 1. Three had metastasis. Among the patients diagnosed by histology (n=24), 12 had mixed GCT, 8 had malignant/immature teratoma, 3 had embryonal carcinoma, and 1 had yolk sac tumor. With a median follow-up of 8 years, 8 patients progressed (local=7, distant=1), and 9 patients died (progression=5, palliative treatment for congenital tumors=2, sepsis=1, procedural complication=1). The respective 5-year PFS and OS were 74.9±6.9% and 82.2±6.1%. In multivariate analysis, high serum hCG level and no radiation use were significantly associated with inferior PFS. Outcome did not differ according to chemotherapeutic reagents used or radiation fields. Four patients had growing teratoma syndrome. Long-term neuroendocrine sequalae were common. In conclusion, children with NGGCT had reasonable outcome after multi-modal therapy in Hong Kong. Effort should be made to minimize tumor and treatment-related toxicities. The role of tumor markers for risk-stratification within NGGCT needs to be further interrogated.
HGG-02. NEUROPHYSIOLOGICAL SMALL MOLECULE SCREEN TO TARGET NEURON-GLIOMA INTERACTIONS IN PEDIATRIC HIGH-GRADE GLIOMAS
Authors: Rogawski David , Mulinyawe Sara , Thomas Craig , Monje Michelle 
Published: June 2021

Abstract
Neurons stimulate glioma growth via synaptic and paracrine signaling mechanisms. We recently demonstrated that neurons form AMPA receptor-dependent synapses with glioma cells, and that neuronal activity also induces potassium-evoked currents that are amplified by gap junctions coupling glioma cells. However, our understanding of the neurotransmitters, receptors, and ion channels participating in neuron-glioma signaling remains incomplete. We have recently developed a high-throughput neuron-glioma co-culture strategy to screen small molecules for agents that may disrupt neuron-glioma signaling. Glioma cell proliferation is increased tenfold when cultured together with neurons; this robust biological effect can be probed in a targeted screen of compounds influencing neurotransmitter receptors and ion channels. The neurophysiological small molecule library used was curated to include approved anti-epileptics, neuroleptics, and antidepressants, as well as a variety of other compounds acting on different neurotransmitter types and ion channels. Hits from the primary screen were run through a counter-screen using glioma cells grown alone without neurons, to identify compounds that specifically affect neuron-glioma interactions. Correlation of the screening results with drug mechanisms of action will allow us to map out the key neurotransmitter pathways regulating glioma growth, which can be further validated using genetic and in vivo experiments. Drugs identified in this glioma neuroscience screen may be readily translated into much-needed therapeutics for children with high-grade glioma.
HGG-06. EARLY GABAERGIC NEURONAL LINEAGE DEFINES DEPENDENCIES IN HISTONE H3 G34R/V GLIOMA
Authors: Liu Ilon , Bjerke Lynn , Cruzeiro Gustavo Alencastro Veiga , Rogers Rebecca F , Grabovska Yura , Panditharatna Eshini , Mackay Alan , Barron Tara , Shaw McKenzie , Hoffman Samantha E , Hack Olivia A , Quezada Michael A , Dempster Joshua , Temelso Sara , Englinger Bernhard , Molinari Valeria , Mire Hafsa M , Jiang Li , Madlener Sibylle , Mayr Lisa , Dorfer Christian , Geyeregger Rene , Rota Christopher , Ricken Gerda , Alexandrescu Sanda , Braun Emelie , Danan-Gotthold Miri , Hu Lijuan , Siletti Kimberly , Sundstroem Erik , Hodge Rebecca , Lein Ed , Agnihotri Sameer , Eisenstat David D , Carceller Fernando , Stapleton Simon , Bleil Cristina , Mastronuzzi Angela , Cole Kristina A , Waanders Angela J , Carcaboso Angel Montero , Vinci Maria , Hargrave Darren , Haberler Christine , Gojo Johannes , Slavc Irene , Linnarsson Sten , Monje Michelle , Jones Chris , Filbin Mariella G 
Published: June 2021

Abstract
High-grade gliomas harboring H3 G34R/V mutations exclusively occur in the cerebral hemispheres of adolescents and young adults, suggesting a distinct neurodevelopmental origin. Combining multimodal bulk and single-cell genomics with unbiased genome-scale CRISPR/Cas9 approaches, we here describe a GABAergic interneuron progenitor lineage as the most likely context from which these H3 G34R/V mutations drive gliomagenesis, conferring unique and tumor-selective gene targets essential for glioma cell survival, as validated genetically and pharmacologically. Phenotypically, we demonstrate that while H3 G34R/V glioma cells harbor the neurotransmitter GABA, they are developmentally stalled, and do not induce the neuronal hyperexcitability described in other glioma subtypes. These findings offer a striking counter-example to the prevailing view of glioma origins in glial precursor cells, resulting in distinct cellular, microenvironmental, and therapeutic consequences.
HGG-07. RADIATION INDUCED SENESCENCE IN DIFFUSE INTRINSIC PONTINE GLIOMA CELLS REVEALS SELECTIVE VULNERABILITY TO BCL-XL INHIBITION
Authors: Vardon Ashley , Guiho Romain , Carvalho Diana , Jones Chris , Hargrave Darren , Martinez-Barbera Juan-Pedro 
Published: June 2021

Abstract
Diffuse intrinsic pontine glioma remains a devastating condition with a dismal five year survival rate less than 5%. New approaches for treating this aggressive disease are critical to driving progress. Conventional radiotherapy remains the cornerstone of treatment, with no chemotherapeutic agent found to improve survival. However, radiotherapy is often delivered as a palliative treatment, and disease often recurs 3–6 months after. Radiation causes DNA damage and oxidative stress yielding a senescent state of replicative arrest in susceptible cells. However, increasing evidence demonstrates malignant cells can escape senescence leading to tumour recurrence. Targeted ablation of non-replicating senescent tumour cells following radiation could negate tumour recurrence. It remains unknown whether DIPG undergoes senescence following radiation, and furthermore, whether senolytics can be utilised to target senescent DIPG cells. We employed radiation to induce a senescent state in primary human DIPG cell lines. Senescence was confirmed using SA-β-gal staining, lack of EdU incorporation and qRT-PCR to characterise the SASP in three primary human DIPG cell lines. RNA-sequencing on DIPG cells following radiation revealed senescence and SASP signatures. Viable cells that survive radiation were then utilised to screen candidate senolytic drugs, only Bcl-XL inhibitors demonstrated reproducible senolytic activity in radiation treated DIPG cells. Conversely, Bcl-2 inhibitors failed to show any consistent senolytic activity. These results demonstrate future possibilities of targeting radiation induced senescence in DIPG, using novel senolytic therapies and highlight Bcl-XL dependency as a potential vulnerability of surviving DIPG cells following exposure to radiation.
HGG-11. LEPTOMENINGEAL DISEASE AND TUMOR DISSEMINATION ALONG CSF PATHWAYS IN A MURINE DIPG MODEL: IMPLICATIONS FOR STUDY OF THE TUMOR-CSF-EPENDYMAL MICROENVIRONMENT
Authors: Pan Shelei , Ye Dezhuang , Yue Yimei , Yang Lihua , Pacia Christopher , Dahiya Sonika , Limbrick David , Rubin Joshua , Chen Hong , Strahle Jennifer 
Published: June 2021

Abstract

Background
Leptomeningeal disease and hydrocephalus are present in up to 30% of patients with diffuse intrinsic pontine glioma (DIPG), however there are no animal models of cerebrospinal fluid (CSF) dissemination. As the tumor-CSF-ependymal microenvironment may play an important role in tumor pathogenesis, we identified characteristics of the Nestin-tumor virus A (Nestin-Tva) genetically engineered mouse model (GEMM) that make it ideal to study the interaction of tumor cells with the CSF and its associated pathways with implications for the development of treatment approaches to address CSF dissemination in DIPG.

Methods
A Nestin-TVa model of DIPG utilizing the three most common DIPG genetic alterations (H3.3K27M, PDGF-B, p53) was used for this study. All animals underwent MR imaging and a subset underwent histopathologic analysis with H&E and beta-IV tubulin.

Results
Tumor dissemination within the CSF pathways (ventricles, leptomeninges) was present in 76% (25/33) of animals, with invasion of the choroid plexus, disruption of the ciliated ependyma and regional subependymal fluid accumulation. Ventricular enlargement consistent with hydrocephalus was present in 94% (31/33). Ventricle volume correlated with region specific transependymal CSF flow (periventricular T2 signal), localized anterior to the lateral ventricles. Subependymal tumor cells were also present subjacent to the 4th ventricle in a post-mortem human specimen.

Conclusions
This is the first study to report CSF pathway tumor dissemination an animal model of DIPG and is representative of CSF dissemination seen clinically. Understanding the CSF-tumor-ependymal microenvironment has significant implications for treatment of DIPG through targeting mechanisms of tumor spread within the CSF pathways.
HGG-12. HUMAN IPSC-DERIVED H3.3K27M NEUROSPHERES: A NOVEL MODEL FOR INVESTIGATING DIPG PATHOGENESIS AND DRUG RESPONSE
Authors: Skinner Kasey , Koga Tomoyuki , Miki Shunichiro , Gruener Robert F , Huang R Stephanie , Furnari Frank , Miller C Ryan 
Published: June 2021

Abstract
Diffuse intrinsic pontine glioma (DIPG) is a subset of high-grade glioma that occurs predominantly in children and has no cure. Up to 80% of DIPG harbor a heterozygous point mutation that results in a lysine 27 to methionine substitution in histone variant H3.3 (H3.3K27M). Existing DIPG models have provided insight into the role of H3.3K27M but have limitations: genetically engineered murine models often rely on overexpression of the mutant histone to form tumors; patient-derived xenografts (PDX) are more genetically faithful but preclude examination of the effect of individual mutations on pathogenesis. To address these shortcomings and better recapitulate the genetics of human tumors, we designed a novel DIPG model based on human induced pluripotent stem cells (iPSC) edited via CRISPR to express heterozygous H3.3K27M. Edited iPSC were chemically differentiated into neural progenitor cells, which upon implantation into the brainstems of immunodeficient mice formed diffusely invasive tumors that were histologically consistent with high-grade glioma. Further, neurospheres cultured from primary tumors formed secondary tumors upon reimplantation with more diffuse invasion, suggesting in vivo evolution. To validate this model’s relevance to DIPG transcriptionally, we performed RNA-sequencing on a cohort of primary and secondary tumor neurospheres (termed primary and secondary iDIPG) and compared them to published RNA-seq data from pediatric PDX and patient tumor samples. Hierarchical clustering and principal component analysis on differentially expressed genes (P&lt;0.05) showed that H3.3K27M iDIPG cluster with H3.3K27M PDX and patient tumors. Further, ssGSEA showed that H3.3K27M iDIPG are enriched for astrocytic and mesenchymal signature genes, a defining feature of H3.3K27M DIPG. Finally, we found that primary H3.3K27M iDIPG neurospheres are sensitive to panobinostat, an HDAC inhibitor shown to be effective against H3.3K27M DIPG cells in vitro. Overall, these data suggest that H3.3K27M iDIPG are a promising tool for investigating DIPG biology and new therapeutic strategies.
HGG-15. THE IMIPRIDONE ONC201 IN COMBINATION WITH THE ONCOLYTIC ADENOVIRUS DELTA-24-RGD HAS A SYNERGISTIC EFFECT IN PRECLINICAL MODELS OF PHGGS AND DMGS
Authors: de la Nava Daniel , Ausejo-Mauleon Iker , Laspidea Virginia , Marrodán Lucía , Zalacain Marta , Herrador-Cañete Guillermo , Nazarian Javad , Mueller Sabine , Allen Joshua E , Fueyo Juan , Gomez-Manzano Candelaria , Gupta Sumit , Patiño Ana , Alonso Marta M 
Published: June 2021

Abstract
Pediatric High Grade Gliomas (pHGGs), including Diffuse Midline Gliomas (DMGs), are aggressive pediatric tumors with a poor overall survival. In the last years, ONC201 has emerged as a promising agent in the field of pediatric brain tumors. Another interesting approach is virotherapy; Delta-24-RGD, which is an oncolytic virus, has demonstrated safety and effectiveness in different preclinical models and in clinical trials. Therefore, in this work we set to evaluate whether the combination of ONC201 with Delta-24-RGD could result in an increased therapeutic benefit in pHGGs and DMGs. Given that ONC201 targets mitochondrial metabolism in a preclinical setting, we assessed potential negative interactions of the combination therapy. While ONC201 treatment resulted in decreased viral protein load (E1A and fiber), there was no significant negative impact on the viral replication (measured by hexon staining). ONC201 did not disrupt the activation of mTORC1 pathway by the adenovirus. Furthermore, Delta-24-RGD did not affect the decrease in basal oxygen consumption rate induced by ONC201. Our results suggested that ONC201 and Delta-24-RGD are not antagonistic. Evaluation of the in vitro cytotoxicity in different human pHGG (CHLA-03-AA and SF188) and DMG (TP-54 and SU-DIPG-IV) cell lines showed that the combination treatment was significantly better that either agent alone. In vivo, a single local injection of Delta-24-RGD followed by a weekly ONC201 of mice bearing CHLA-03-AA cell line orthotopically significantly increased the median overall survival (PBS: 48 days; ONC201: 54.5 days; Delta-24-RGD: 62 days; ONC201+Delta-24-RGD: 95 days (P=0.0008)) of these mice leading to 20% long-term survivors, free of disease. Currently, we are evaluating the effect of the combination in immunosuppressed and immunocompetent models of DMGs. In summary, our data indicate ONC201 in combination with Delta-24-RGD could be a potential therapeutic choice for patients affected by pHGGs and DMGs.
HGG-17. FOCUSED ULTRASOUND-ENHANCED DELIVERY OF RADIOLABELED AGENTS TO DIFFUSE INTRINSIC PONTINE GLIOMA
Authors: Ye Dezhuang , Zhang Xiaohui , Yang Lihua , Yue Yimei , Tai Yuan-chuan , Rubin Joshua B , Liu Yongjian , Chen Hong 
Published: June 2021

Abstract
Diffuse intrinsic pontine glioma (DIPG) arising in the brainstem is the deadliest pediatric brain cancer with nearly 100% fatality and a median survival of &lt;1 year. The critical location in the brainstem and the often intact blood-brain barrier (BBB) pose significant challenges in the treatment of DIPG. The objective of this study was to demonstrate the potential for focused ultrasound-induced BBB disruption (FUS-BBBD) to improve DIPG treatment by enhancing the safe and efficient delivery of drugs. A genetically engineered mouse model of DIPG was generated using the RCAS (replication-competent avian sarcoma-leucosis virus long-terminal repeat with splice acceptor)/tumor virus A modeling system. A magnetic resonance-guided FUS (MRgFUS) system was used to induce BBB disruption in these mice with the FUS targeted at the center of the tumor. Two radiolabeled agents with different sizes were used to evaluate the delivery efficiency of the FUS-BBBD technique in DIPG mice: a small-molecular radiotracer, 68Ga-DOTA-ECL1i, and a radiolabeled nanoparticle, 64Cu-labeled copper nanoparticles (64Cu-CuNCs, ~ 5 nm in diameter). 68Ga-DOTA-ECL1i (half-life ~ 1 h) and 64Cu-CuNCs (half-life ~13 h) were intravenously injected into the mice after FUS sonication, and microPET/CT imaging was performed at 1 h and 24 h, respectively, to evaluate the spatial-temporal distribution of these two agents in the brain and quantify the delivery outcome. FUS treatment increased the uptake of 68Ga-DOTA-ECL1i and 64Cu-CuNCs to the DIPG tumor by 3.25 folds and 4.07 folds on average, respectively. These findings demonstrated, for the first time, that FUS can increase BBB permeability in a murine model of DIPG and significantly enhance the delivery of agents of different sizes into the DIPG tumor.
HGG-22. EVALUATING THE REGULATION OF BLOOD-BRAIN BARRIER INTEGRITY IN DIPG MOUSE MODELS
Authors: Wei Xin , Phoenix Timothy 
Published: June 2021

Abstract
Diffuse intrinsic pontine gliomas (DIPGs) are considered to maintain a fairly intact blood-brain barrier (BBB) based on patient imaging tumor histology. In characterizing recently developed DIPG and HGG mouse models, we identified differences in BBB function and increased Angiopoietin1 (Angpt1) in H3 K27M DIPG models. We hypothesize that H3 K27M mutations promote the maintenance of DIPG BBB integrity through upregulation of Angpt1. To determine DIPG and HGG BBB phenotypes we performed an intergrative analysis of vascular histology and endothelial transcriptomes Ongoing studies using electroporation based DIPG mouse models are being performed examine the regulation and function of Angpt1 in DIPG BBB integrity. We have initiated studies comparing H3 K27M DIPG mouse models to H3 WT and G34R cortical HGG mouse models, demonstrating that DIPG models show minimal changes in vascular phenotype, including vessel density, branching, and diameter compared to cortical HGG models. Comparing DIPG and HGG purified endothelial transcriptomes, HGG ECs displayed enrichments of inflammatory signals and proliferation gene sets, and increased expression of tip cell identity genes. We identified Angpt1 as selectively upregulated in H3 K27M mouse models and derived cell lines. Preliminary data suggests Angpt1 supports the maintenance of BBB integrity in DIPG models. BBB phenotype differences are present in DIPG and HGG mouse models. Uncovering mutation specific mechanisms that regulate BBB function in brain tumors will be critical to advance our understanding of brain tumor pathogenesis and treatment response.