bluuebunny/crossref_metadata_2025 huggingface dataset:
Jets from main sequence and white dwarf companions during common envelope evolution
Authors: Zou Yangyuxin , Chamandy Luke , Carroll-Nellenback Jonathan , Blackman Eric G , Frank Adam
Published: June 2022

It has long been speculated that jet feedback from accretion on to the companion during a common envelope (CE) event could affect the orbital evolution and envelope unbinding process. We present global 3D hydrodynamical simulations of CE evolution (CEE) that include a jet subgrid model and compare them with an otherwise identical model without a jet. Our binary consists of a 2-M⊙ red giant branch primary and a 1- or 0.5-M⊙ main sequence (MS) or white dwarf (WD) secondary companion modelled as a point particle. We run the simulations for 10 orbits (40 d). Our jet model adds mass at a constant rate $\dot{M}_\mathrm{j}$ of the order of the Eddington rate, with maximum velocity vj of the order of the escape speed, to two spherical sectors with the jet axis perpendicular to the orbital plane. We explore the influence of the jet on orbital evolution, envelope morphology and envelope unbinding, and assess the dependence of the results on the jet mass-loss rate, launch speed, companion mass, opening angle, and accretion rate. In line with our theoretical estimates, jets are choked around the time of first periastron passage and remain choked thereafter. Subsequent to choking, but not before, jets efficiently transfer energy to bound envelope material. This leads to increases in unbound mass of up to $\sim 10{{\ \rm per\ cent}}$, as compared to the simulations without jets. We also estimate the cumulative effects of jets over a full CE phase, finding that jets launched by MS and WD companions are unlikely to dominate envelope unbinding.
Web-based platform for analysis of RNA folding from high throughput chemical probing data
Authors: Jurich Christopher P , Brivanlou Amir , Rouskin Silvi , Yesselman Joseph D
Published: June 2022

RNA structures play critical roles in regulating gene expression across all domains of life and viruses. Chemical probing methods coupled with massively parallel sequencing have revolutionized the RNA structure field by enabling the assessment of many structures in their native, physiological context. Previously, we developed Dimethyl-Sulfate-based Mutational Profiling and Sequencing (DMS-MaPseq), which uses DMS to label the Watson-Crick face of open and accessible adenine and cytosine bases in the RNA. We used this approach to determine the genome-wide structures of HIV-1 and SARS-CoV-2 in infected cells, which permitted uncovering new biology and identifying therapeutic targets. Due to the simplicity and ease of the experimental procedure, DMS-MaPseq has been adopted by labs worldwide. However, bioinformatic analysis remains a substantial hurdle for labs that often lack the necessary infrastructure and computational expertise. Here we present a modern web-based interface that automates the analysis of chemical probing profiles from raw sequencing files (http://rnadreem.org). The availability of a simple web-based platform for DMS-MaPseq analysis will dramatically expand studies of RNA structure and aid in the design of structure-based therapeutics.
Chemoenzymatic labeling of DNA methylation patterns for single-molecule epigenetic mapping
Authors: Gabrieli Tslil , Michaeli Yael , Avraham Sigal , Torchinsky Dmitry , Margalit Sapir , Schütz Leonie , Juhasz Matyas , Coruh Ceyda , Arbib Nissim , Zhou Zhaohui Sunny , Law Julie A , Weinhold Elmar , Ebenstein Yuval
Published: June 2022

DNA methylation, specifically, methylation of cytosine (C) nucleotides at the 5-carbon position (5-mC), is the most studied and significant epigenetic modification. Here we developed a chemoenzymatic procedure to fluorescently label non-methylated cytosines in CpG context, allowing epigenetic profiling of single DNA molecules spanning hundreds of thousands of base pairs. We used a CpG methyltransferase with a synthetic S-adenosyl-l-methionine cofactor analog to transfer an azide to cytosines instead of the natural methyl group. A fluorophore was then clicked onto the DNA, reporting on the amount and position of non-methylated CpGs. We found that labeling efficiency was increased up to 2-fold by the addition of a nucleosidase, presumably by degrading the inactive by-product of the cofactor after labeling, preventing its inhibitory effect. We used the method to determine the decline in global DNA methylation in a chronic lymphocytic leukemia patient and then performed whole-genome methylation mapping of the model plant Arabidopsis thaliana. Our genome maps show high concordance with published bisulfite sequencing methylation maps. Although mapping resolution is limited by optical detection to 500–1000 bp, the labeled DNA molecules produced by this approach are hundreds of thousands of base pairs long, allowing access to long repetitive and structurally variable genomic regions.
The snoGloBe interaction predictor reveals a broad spectrum of C/D snoRNA RNA targets
Authors: Deschamps-Francoeur Gabrielle , Couture Sonia , Abou-Elela Sherif , Scott Michelle S
Published: June 2022

Box C/D small nucleolar RNAs (snoRNAs) are a conserved class of RNA known for their role in guiding ribosomal RNA 2′-O-ribose methylation. Recently, C/D snoRNAs were also implicated in regulating the expression of non-ribosomal genes through different modes of binding. Large scale RNA–RNA interaction datasets detect many snoRNAs binding messenger RNA, but are limited by specific experimental conditions. To enable a more comprehensive study of C/D snoRNA interactions, we created snoGloBe, a human C/D snoRNA interaction predictor based on a gradient boosting classifier. SnoGloBe considers the target type, position and sequence of the interactions, enabling it to outperform existing predictors. Interestingly, for specific snoRNAs, snoGloBe identifies strong enrichment of interactions near gene expression regulatory elements including splice sites. Abundance and splicing of predicted targets were altered upon the knockdown of their associated snoRNA. Strikingly, the predicted snoRNA interactions often overlap with the binding sites of functionally related RNA binding proteins, reinforcing their role in gene expression regulation. SnoGloBe is also an excellent tool for discovering viral RNA targets, as shown by its capacity to identify snoRNAs targeting the heavily methylated SARS-CoV-2 RNA. Overall, snoGloBe is capable of identifying experimentally validated binding sites and predicting novel sites with shared regulatory function.
ATRT-04. Clinical and (epi)genetic characterisation of patients with atypical teratoid/rhabdoid tumor (ATRT) and extracranial malignant rhabdoid tumor conceived following assisted reproduction technologies (ART)
Authors: Nemes Karolina , Benesch Martin , Kolerova Julia , Johann Pascal , Hasselblatt Martin , Thomas Christian , Bens Susanne , Liaugaudiene Olga , Sadeghipour Alireza , von der Weid Nicolas , Schmid Irene , Gidding Corrie , Erdreich-Epstein Anat , Khurana Claudia , Ebetsberger-Dachs Georg , Lemmer Andreas , Marqués Carmen Hernández , Khatib Ziad , Pears Jane , Quehenberger Franz , Biegel Jaclyn A , Siebert Reiner , Frühwald Michael C
Published: June 2022

INTRODUCTION: Anecdotal case reports suggest an association between assisted reproduction technologies (ART) and malignant rhabdoid tumors (MRT). We performed a multi-institutional retrospective analysis of the EU-RHAB database, complemented by additional cases outside of EU-RHAB to compile clinical, (epi)genetic characteristics and outcome data of children with MRT following ART. METHODS: Data of 14 patients (from 311 patients with MRT) from 9 countries were analyzed (2010-2018). Tumors and matching blood samples were examined for SMARCB1 mutations using FISH, MLPA and sequencing. Molecular subgroups were determined using DNA methylation arrays and correlated with a validation cohort (n=22, tumor samples of MRT; n=39 blood samples of patients small for gestational age). RESULTS: The median age at diagnosis of the 13 girls and 1 boy was 9 months (0 – 66). 8 patients with ATRT, 3 with extracranial, extrarenal-, 1 with renal rhabdoid tumor and 2 with synchronous tumors were identified. Distant metastases at diagnosis were present in 6 patients. A germline mutation (GLM) was detected in 5 patients. In 11 tumors complete data on SMARCB1 mutational status were available. DNA methylation subgrouping was available in 10 tumors and 6 blood samples. A female predominance was noted as compared to the EU-RHAB cohort with MRT born without ART (n=213, p=0.009). A total of 8 patients received gross total resection, n=12 patients received conventional chemotherapy (EU-RHAB=9, Head Start II=2, IRS III=1). Radiotherapy was applied to 6 patients. 10 patients achieved CR, and 5 remain in continuing CR. Significant genome-wide DNA methylation differences (including imprinted genes) between patients born after ART and patients born without ART could not be demonstrated. CONCLUSIONS: Long-term survival is achievable in patients who develop MRT after ART, even in cases with GLM, metastatic disease at diagnosis, or relapse. Larger epidemiological studies are needed to confirm a potential association between MRT and ART.
ATRT-12. LIN28A expression correlates with poor prognosis and the MYC subgroup in AT/RTs
Authors: Dottermusch Matthias , Brakopp Sina , Struve Nina , Frühwald Michael C , Merk Daniel J , Tabatabai Ghazaleh , Schüller Ulrich , Hasselblatt Martin , Neumann Julia E
Published: June 2022

Atypical teratoid/rhabdoid tumors (AT/RTs) are malignant embryonal tumors of the central nervous system, which mainly affect young children. These tumors are defined by loss of SMARCB1 (or SMARCA4 in rare cases) and can be categorized into three main DNA methylation subgroups (i.e. –MYC, -SHH, -TYR). AT/RTs commonly display heterogeneous expression of LIN28A, an RNA-binding protein, which regulates pluripotency and plays critical roles during embryonic development. The biological impact and clinical significance of LIN28A expression in AT/RTs remains unknown. In this study, we investigated 80 samples of molecularly and clinically characterized AT/RTs for LIN28A expression using immunohistochemistry. Staining signal of tumor tissue was assessed and scored via semi-automated digital image analysis. Global LIN28A expression intensity and heterogeneity were tested for correlation with DNA methylation subtype, tumor localization, as well as patient age, gender and overall survival. LIN28A was found with strongly varying staining patterns and intensities across our cohort of AT/RTs, with significantly elevated expression in the MYC subgroup. Moreover, we identified strong global and focal LIN28A expression as an independent negative prognostic factor in AT/RTs. In summary, we show that AT/RT-MYC tumors display significantly increased LIN28A expression in comparison to the other DNA methylation subgroups, suggesting a subgroup-specific intratumoral role of LIN28A. Furthermore, we demonstrate an impact of LIN28A expression on survival in AT/RTs. Further investigations on the functions of LIN28A in AT/RTs in vitro and in vivo are ongoing and aim to uncover potential therapeutic implications in these tumors.
ATRT-23. SIRT2 cooperates with SMARCB1 to induce a differentiation block in ATRT
Authors: Alimova Irina , Wang Dong , Pierce Angela , Lakshmanachetty Senthilnath , Prince Eric , Danis Etienne , Serkova Natalie , Madhavan Krishna , Balakrishnan Ilango , Yang Min , Lin Henning , Foreman Nicholas , Venkataraman Sujatha , Vibhakar Rajeev
Published: June 2022

Atypical Teratoid Rhabdoid Tumor is a highly aggressive pediatric brain tumor with poor prognosis driven by loss of the chromatin remodeling factor SMARCB1 that is responsible for determining cellular pluripotency and lineage commitment. The mechanisms by which SMARCB1 deletion results in tumorigenesis remain unclear. We investigated the effect of SIRT2 inhibition in ATRT which was identified as a primary dependency in ATRT. SIRT2 inhibition with shRNA or Thiomyristoyl (TM) decreased ATRT cell growth, inhibited clonogenic potential and leaded to the cell cycle arrest. SIRT2 inhibition effectively suppresses pluripotency-associated genomic programs, significantly changed stem cell frequency, decreased tumor-sphere formation of ATRT cells and attenuated tumor cell self-renewal. In vivo SIRT2 inhibition decreased oncogenic markers and increased accumulation neuronal differentiation markers. Furthermore, SIRT2 induced apoptosis, decreased tumor growth and prolonged survival in orthotopic xenograft models. Single-cell RNA transcriptome analysis of xenoftaft tumors reveals elimination of tumor cells expressing stem cell genes and expansion of tumor cells expressing differentiated genes following TM treatment in ATRT. We demonstrated that SIRT2 inhibition is a molecular vulnerability in SMARCB1-deleted ATRT.
ATRT-24. CDK7 Inhibition in AT/RT
Authors: Morin Andrew , Wodetzki Darya , Veo Bethany , Pierce Angela , Zahedi Shadi , Crespo Michele , Venkataraman Sujatha , Vibhakar Rajeev , Mulcahy-Levy Jean
Published: June 2022

Atypical teratoid/rhabdoid tumors (AT/RT) are CNS tumors with a 5-year survival of ~35%. AT/RT is characterized by loss-of-function mutations in the SMARCB1 component of the SWI/SNF (SWItch/Sucrose Non-Fermentable) complex. Based on preliminary CRISPR-Cas9 gene essentiality screen results identifying AT/RT vulnerabilities, we hypothesized that interaction between CDK7 and the SWI/SNF complex via SMARCB1 provides a potential target to improve clinical survival of patients. CDK7 expression was identified by microarray in AT/RT, medulloblastoma, glioblastoma and normal brain. Established cell lines (BT12, BT16, CHLA06), patient derived lines (MAF-737, MAF-1298, MAF-1337), normal human astrocytes (NHA) and NIH3T3 mouse embryonic fibroblast cells were utilized for in vitro response to CDK7 inhibition. Murine cerebellar xenografts of MAF-737 were utilized to evaluate genetic and pharmacologic response to CDK7 inhibition. The NCI Approved Oncology Drugs (AOD-9) Panel was evaluated with an IC25 dose of CDK7 inhibitor THZ2 to identify potential synergistic combinations. CDK7 is up-regulated in AT/RT compared to other brain tumors or normal brain. In vitro, AT/RT cells are highly susceptible to CDK7 pharmacologic inhibition with nM IC50 levels. AT/RT cells with shRNA against CDK7 implanted in vivo show significantly reduced growth. Evaluation of in vivo tumors treated with THZ2 demonstrate decreased Ki-67 and reduced pRBP1 demonstrating effective inhibition of the target as well as a decrease in cell proliferation. Combination therapy of THZ2 with the AOD-9 Panel found significant synergy with antimetabolite therapies, specifically pemetrexed, pralatrexate, and methotrexate. There was no synergy with other standard chemotherapy. Our findings demonstrate that CDK7 is highly expressed in AT/RT and necessary for proliferation of AT/RT cells, suggesting it as a potential therapeutic target. Antimetabolites, which are currently used in several AT/RT protocols, synergized with CDK7 inhibition offers a potential future combination therapy for patients.
RARE-01. Cerebral infarction in childhood-onset craniopharyngioma patients: results of KRANIOPHARYNGEOM 2007
Authors: Boekhoff Svenja , Bison Brigitte , Eveslage Maria , Friedrich Carsten , Flitsch Jörg , Müller Hermann L
Published: June 2022

BACKGROUND: Cerebral infarction (CI) is a known vascular complication following treatment of suprasellar tumors. Risk factors for CI, incidence rate, and long-term prognosis are unknown for patients with childhood-onset craniopharyngioma (CP). METHODS: MRI of 244 CP patients, recruited between 2007 and 2019 in KRANIOPHA-RYNGEOM 2007, were reviewed for CI. Risk factors for CI and outcome after CI were analyzed. RESULTS: Twenty-eight of 244 patients (11%) presented with CI based on reference assessment of MRI. One CI occurred before initial surgery and one case of CI occurred after release of intracystic pressure by a cyst catheter. 26 of 28 CI were detected after surgical tumor resection at a median postoperative interval of one day (range: 0.5 - 53 days). Vascular lesions during surgical procedures were documented in 7 cases with CI. No relevant differences with regard to surgical approaches were found. In all 12 irradiated patients, CI occurred before irradiation. Multivariable analyses showed that hydrocephalus and gross-total resection at the time of primary diagnosis / surgery both were risk factors for CI. After CI, quality of life (PEDQOL) and functional capacity (FMH) were impaired. CONCLUSIONS: CI occurs in 11% of surgically-treated CP cases. Degree of resection and increased intracranial pressure are risk factors, which should be considered in the planning of surgical procedures for prevention of CI.
RARE-12. Pineoblastoma of children and young adults in a national population: An analysis of the HIT-MED study cohort
Authors: Yuan Mathias , Mynarek Martin , Goschzik Tobias , Pfaff Elke , Kortmann Rolf , Bison Brigitte , Warmuth-Metz Monika , Schiller Ulrich , Hagel Christian , Obrecht Denise , Benesch Martin , Pfister Stefan M , Pietsch Torsten , Rutkowski Stefan
Published: June 2022

BACKGROUND: Pineoblastoma is a malignant tumor of the pineal gland and accounts for <1% of all pediatric brain tumors. PURPOSE/METHODS: Patients <21 years (y) with pineoblastoma confirmed by central neuropathology review between 2001–2021 and included into the HIT2000 trial, HIT2000interim- or I-HIT-MED-registries were eligible. RESULTS: 88 patients were identified. Age at diagnosis was 0.01–20.71y (median 9.34y), median follow-up was 6.54y (IQR 1.78–12.41y) in 48 patients alive at last follow-up. 20 patients were <4y and received chemotherapy with intent to avoid radiotherapy. Of these, 7 patients were alive at last follow-up, two patients were radiotherapy-naïve and 5 patients had undergone CSI + boost (4 after incomplete response and one after progression). 5-y-PFS/OS in 68 patients >4y differed according to metastatic status (M0 (n=40) 72.7±8.3%/75.0±8.3%; M+ (n=28) 28.7±10.3%/40.8±10.9%, p=0.001/0.001). Therapy escalation in M0 patients by giving SKK chemotherapy before radiotherapy did not improve PFS/OS compared to upfront radiotherapy (5-y-PFS/OS 70.7±14.3%/70.0±14.5% vs 74.2±10.1%/78.9±9.4%, p=0.61/0.73). Applied CSI dosages were 24–50Gy (mean 35.6Gy) with no prognostic value of specific dosages being observed. Similarly, in M0 patients hyperfractionated radiotherapy (2x1.0Gy/d, total dose (TD) 36Gy, n=23) was not superior to conventional radiotherapy (1.6Gy/d, TD 35.2Gy, n=7). In all patients, favorable prognostic factors were age >4y (5-y-PFS/OS 54.1±7.0%/60.0±7.0% vs 30.0 ±10.2%/35.0±10.7%, p=0.012/0.053) and radiotherapy in primary therapy (5-y-PFS/OS 55.8±6.5%/61.4±6.4% vs 14.4±9.4%/21.4±11.0%, p<0.001/=0.003), whereas unfavorable prognosis was associated with metastatic disease (5-y-PFS/OS 33.6±9.0%/45.9±9.3% vs 58.8±7.6%/59.3±7.7%, p=0.028/0.086). CONCLUSION: Survival is poor in pineoblastoma patients <4y treated without radiotherapy. Unfavorable prognosis was associated with metastatic disease, especially in older children. Chemotherapy combined with CSI is effective for non-metastatic patients at age >4y. Further research will consider biological subgroups to enhance risk stratification and identify approaches for therapy improvements.
RARE-20. Retrospective analysis of 9 pineoblastoma
Authors: Ai Ruyu , Li Juan , Lai Mingyao , Cai Linbo
Published: June 2022

BACKGROUND: Pineoblastomas (PBs) are rare, supratentorial, primitive neuroectodermal tumors. Little is known with the clinical features and outcomes of PBs. METHODS: We retrospectively analyzed consecutive patients with PBs who were treated in Guangdong Sanjiu Brain Hospital between December 2006 to May 2020. RESULTS: A total of 9 patients (7 males and 2 females) with PBs were treated in our hospital with a median age of 9 yrs (range: 1-36 yrs) at diagnosis. Total or near-total resection was achieved in 3 patients (33%), partially resection in 4 (44.4%),and biopsy in 2(22.2%). There were 4 patients have spinal cord metastasis at diagnosis. Five patients received craniospinal irradiation (CSI), with concurrent or adjuvant chemotherapy. The average total dose of CSI was 34.80±2.683Gy, and the average dose to local tumor bed was 56.08±6.41Gy. Two patients younger than 3 years old only received chemotherapy, while 1 patient did not receive any postoperative treatment, and 1 patients was unknown. The median followed up time is ? months(range:3-39 months). At the last follow up, 5 patients were died, 3 patients were survived, and 1 was lost to follow-up. The median OS was 31 months (95%CI 1.782-60.281). Disease progression occurred in 5 patients during the follow-up period, and the median PFS was 19 months. CONCLUSION: Pineoblastoma is a rare central nervous system malignancy with a tendency for disseminated disease. Comprehensive therapies such as surgical resection, radiation and chemo therapy are effective therapies for PBs.
RARE-27. Treatment and outcomes in atypical choroid plexus papilloma: a single institution experience
Authors: Cluster Andrew , Cantor Evan , Meyer Ashley , Ogle Andrea , McEvoy Sean , Strahle Jennifer , Brossier Nicole , Shatara Margaret , Limbrick David , Abdelbaki Mohamed
Published: June 2022

BACKGROUND: Atypical choroid plexus papillomas (aCPP) are rare central nervous system (CNS) tumors often occurring in very young children. While surgical resection has been a mainstay of therapy, there is no consensus and limited data on the treatment of relapsed or metastatic tumors. METHODS: Retrospective review of the treatment and outcome of patients diagnosed with aCPP since 2011 was performed. RESULTS: Of the seven patients, 4 were male and 3 were female with a median age of 3 years at diagnosis (range: antenatal to 18 years old). All non-metastatic patients (six) were treated with surgery and all achieved gross total resection. Two patients had diffuse leptomeningeal contrast enhancement on diagnosis MRI that resolved after resection of primary tumor alone. One patient developed local relapse underwent re-resection with a GTR then was treated with 4 cycles of chemotherapy based on CPT-SIOP-2000 protocol (carboplatin, etoposide) and has not had further relapse in 24 months. One patient had metastatic disease at the time of diagnosis. They were treated with adjuvant chemotherapy, which stabilized disease for 36 months until they had progression. Additional four cycles were given and has again stabilized disease now 8 months from completion of that therapy. One non-metastatic patient died of unknown causes 28 months from diagnosis. CONCLUSIONS: Surgical resection remains the standard of care for patients with aCPP. However, chemotherapy based on the SIOP backbone may be useful to reduce the need for or to delay radiation therapy in select patients in the relapsed or metastatic setting.
DIPG-03. Therapeutic targeting of purine biosynthesis in DIPG
Authors: Mersich Ian , Dasgupta Biplab
Published: June 2022

Diffuse intrinsic pontine glioma (DIPG) is an incurable brainstem malignancy in children. Little progress has been made in treating this deadly disease due to its inoperable location and treatments aimed at targets defined in adult gliomas. Currently there are no targeted therapies that significantly improve overall survival in patients with this disease. To this end, we are developing a metabolic profile for this disease by integrating metabolomics and gene expression data from cell lines derived from DIPG patient tumors. Our long-term goal is to significantly improve the overall survival of children with DIPG by identifying novel therapeutic targets. Central to this goal is our investigation into dysregulated purine metabolism in these tumors. We’ve integrated gene expression and metabolomic datasets for DIPG cells and identified a potential therapeutic target in the de novo purine biosynthesis (DNPB) pathway. Genetic knockout experiments confirmed that DIPG cells require the last enzyme in the DNPB pathway, ATIC, for survival. Furthermore, we have identified a compound that disrupts ATIC homo-dimerization, which is required for ATIC catalytic activity. Our preliminary data demonstrates this compound may offer clinical benefits over traditional antifolates that target this same pathway; however, the mechanism leading to selective cytotoxicity was unclear. Antifolates such as methotrexate competitively inhibit folate binding sites in multiple enzymes within this pathway; however, there are known mechanisms of resistance to these drugs. We show that the ATIC dimerization inhibitor differs from the antifolates by disrupting a multi-enzyme complex known as the purinosome, which requires intact, functional ATIC for assembly. Furthermore, targeting ATIC through genetic and pharmacological inhibition in vivo has extended survival in our PDX mouse model of DIPG.
DIPG-08. The development of ACT001 as a novel therapeutic for diffuse intrinsic pontine gliomas
Authors: Upton Dannielle , George Sandra , Liu Jie , Cai Dongpo Doug , Su Steven Yung-Chang , Rayner Benjamin , Tsoli Maria , Ziegler David
Published: June 2022

Diffuse Intrinsic Pontine Gliomas (DIPG) are a subset of Diffuse Midline Gliomas (DMG) and are the most devastating of all brain tumours. There are currently no effective treatments. ACT001 is a novel anti-cancer agent in clinical development that is blood-brain-barrier permeable. Previous studies undertaken in adult glioblastoma suggest that ACT001 exerts an anti-tumour effect via induction of oxidative stress and inhibition of NF-kB and STAT3 pathways. In DIPG, we have found that ACT001 demonstrated potent cytotoxic activity against a panel of DIPG neurospheres and also inhibited colony formation. Flow cytometric analysis confirmed the induction of apoptosis in vitro. Interestingly, we also observed increased expression of some markers of the ROS-dependant NRF2 endogenous antioxidant pathway within DIPG neurospheres suggesting an alternative mechanism of inhibition of DIPG cell proliferation involving ROS generation. In vivo testing of ACT001 in a highly aggressive DIPG-orthotopic model showed that ACT001 was well tolerated and significantly improved survival. ACT001 treatment of HSJD-DIPG007 tumour-bearing animals extended median survival from 59 to 78 days (p=0.0005). ACT001 treated mice had significantly decreased proliferating DIPG cells, analysed by Ki67 staining (p=0.01), and significantly increased H3K27me3 staining (p=0.0479). Given the significant effects on H3K27me3 we evaluated two potential drug combinations with known, clinically available epigenetic modifers. Combination of ACT001 with the FACT inhibitor CBL0137 or the HDAC inhibitor SAHA each significantly and synergistically decreased colony formation. These combinations are currently being evaluated in vivo in orthotopic models of DIPG. ACT001 is currently in a Phase 1 paediatric trial for children with DIPG/DMG. Clinical activity has been demonstrated in DIPG/DMG patients, including a reduction in tumour burden and clinical response. These combined preclinical and clinical results suggest that ACT001 is a viable therapy for patients with DIPG/DMG and preclinical combination therapy testing may guide further clinical trials.
DIPG-17. CD155 regulates cell growth and immune evasion in diffuse intrinsic pontine glioma
Authors: Tzaridis Theophilos , Eisemann Tanja , Andrade Augusto F , Hope Jennifer L , Romero Megan M , Becher Oren J , Jabado Nada , Bradley Linda M , Wechsler-Reya Robert J
Published: June 2022

There is an unmet need for more effective treatment strategies for diffuse intrinsic pontine glioma (DIPG), a devastating brain tumour arising in children and young adults. While immunotherapy is emerging as a powerful approach to treatment of other cancers, clinical trials with immune checkpoint inhibitors have failed to show a survival benefit for DIPG patients. In this study, we analysed the expression of immune checkpoint molecules on the surface of human and murine DIPG cells by flow cytometry and identified CD155 and B7-H3 as the most highly expressed checkpoint molecules, with minimal expression of PD-L1, PD-L2, Galectin-9, CEACAM-1, CD86, CD252 and CD137. These findings were confirmed in primary patient samples from pediatric brain tumours, including high-grade gliomas, medulloblastomas and ependymomas. To test whether CD155 inhibition increases susceptibility to CD8+ T cell killing in vitro, we cultured DIPG cells expressing ovalbumin (OVA) with CD8+ T cells from OT-I mice, which express T cell receptors specific for OVA. Addition of CD155 blocking antibodies to these cultures increased expression of T cell activation markers (CD25, CD44 and CD69) as well as T cell-mediated tumour killing, supporting the notion that CD155 can function as an immune checkpoint in DIPG. In addition to its effects on T cells, CD155 also exerted direct effects on tumour cells: treatment with anti-CD155 antibodies led to impaired cell viability, and shRNA-mediated knockdown of CD155 resulted in reduced cell proliferation in vitro. Strikingly, knockdown of CD155 also led to reduced growth of DIPG cells in vivo, and mice transplanted with the CD155-deficient cells had a clear survival benefit compared to mice transplanted with wild type cells. These studies demonstrate that CD155 functions as an immune checkpoint and as a regulator of tumor growth in DIPG, and suggest that targeting CD155 could be a valuable therapeutic strategy for this devastating disease.
DIPG-27. Behavioral disturbances as underestimated presenting symptoms in children with Diffuse Intrinsic Pontine Glioma (DIPG)
Authors: Milanaccio Claudia , Profio Sonia Di , De Giuseppe Sara , Ramaglia Antonia , Verrico Antonio , Crocco Marco , Piccolo Gianluca , Satragno Camilla , Biassoni Veronica , Garrè Maria Luisa
Published: June 2022

PURPOSE: to describe how often behavioral and emotional changes occur at diagnosis in children with DIPG, or precede it. METHODS: the anamnesis, clinical history, psychological evaluation, and onset symptoms of all cases of DIPG diagnosed at Gaslini Institute between January 2010 and December 2020 were reviewed. RESULTS: 20 DIPGs were diagnosed, 7 males, with a median age of 7,6 years (range 2,4-16,2). All patients presented typical neurological symptoms: 16 had cranial nerves palsy, 12 ataxia, 8 dysarthria, 5 dysphagia, 5 hemiparesis, 5 headache, and 2 obstructive hydrocephalus. Behavioral disorders were found in 14 cases, with several manifestations and in various association: irritability and aggressive behavior in 6, ideomotor slowdown and apathy in 5, emotional dysregulation in 4, mood deflection in 3, sleep disturbances (i.e. nightmares, insomnia, and somniloquy) in 3, marked behavioral changes, school phobia and separation anxiety in 2, depersonalization crisis and phobia of waterdrops in the eyes in 2 patients each. In 6 cases behavioral disturbances were the presenting symptom, appearing one to twelve months earlier than the classic neurological deficits. In all patients, behavioral symptoms improved during Radiotherapy. CONCLUSIONS: behavioral disturbances, although well-known and described in the literature, are not commonly reported among the onset symptoms of DIPG, thus being probably underestimated. Their pathogenesis can be explained by neurophysiology: the brainstem contains reciprocal cerebro-ponto-cerebellar connections whose disruption compromises their modulatory function on affective and cognitive behavior. Furthermore, the reticular formation contains aggregates of neurons regulating several complex functions including the state of alertness (e.g. sleep and wakefulness), the perception of pain, and cognitive functions (e.g. attention, mood, and memory). A careful anamnestic and medical history together with a detailed psychological assessment should be always performed in all DIPGs at diagnosis, in order to bring out those underlying behavioral disorders which could benefit from early neuropsycological support.
DIPG-33. Treating Pediatric Diffuse Intrinsic Pontine Glioma with Brain Radiation and Temozolomide: A Case Report
Authors: Ramadhan Diko Anugrah , Gautami Wanda , Rahmartani Ludi Dhyani , Rafli Achmad , Handoko Handoko , Nuryadi Endang , Amal Mohamad Yanuar
Published: June 2022

Diffuse Intrinsic Pontine Gliomas (DIPG) is a rare and highly aggressive central nervous system tumour arising from glial cells which occur mostly in children. It remains a potentially deadly cancer despite treatment, with the highest mortality rate, in which most children die within 1-year of diagnosis. Radiation therapy might improve the clinical symptoms, but the results are temporary, with tumor progression typically occurring months post radiation, whereas chemotherapy remains controversial. Here we present a case report of a patient with DIPG Indonesia and how we diagnose and currently treat it. An eight years-old boy presented with decrease level of consciousness with headache, limb weakness, slurred speech, double vision, hemifacial weakness, paraplegia, and disequilibrium which worsened two weeks prior to admission. He was initially noted to have a medially inverted left eye two months prior to admission. On physical examination, there was a N.VI and N.VII palsy, hyperreflexia, paraplegia, and nystagmus. Head MRI demonstrated a solid with minimal enhancement after contrast administration in the left pons region extending into mesencephalon with cystic component and flat floor of fourth ventricle sign, causing hydrocephalus, suggestive diffuse intrinsic pontine glioma. He was given fractionated focal intensity modulated radiation therapy (IMRT) to the tumor along with 5 mm margins with a total dose of 54 Gy. 1.8 Gy fractions, given once daily for 5 days per week over a period of 6 weeks. Supportive care in the form of corticosteroids is used to treat the peri-tumoral edema. There was a short period of motoric improvement. But then the disease progressed with the latest head CT showed hydrocephalus formation with increased size of mass. He is treated with chemotherapy using Temozolomide, and currently alive after 3 months post diagnosis.

Keywords: childhood brain tumour, Diffuse Intrinsic Pontine Glioma, radiation therapy
DIPG-35. Personalized treatment for molecularly heterogeneous Diffuse midline glioma, H3 k27-altered Paediatric case
Authors: Mobark Nahla Ali , Alharbi Musa , Bayoumi Yasser S , Albanyan Aymn , Balbaid Ali Abdullah O , Aljabarat Wael abdel Rahman , Abedalthagafi Malak
Published: June 2022

Diffuse midline glioma, H3 k27-altered (DMG) is a type of Paediatric- type diffuse high grade gliomas according to the 2021 WHO CNS tumors Classification. Diffuse intrinsic pontine glioma (DIPG) is another acceptable related term when it located in the pons with fatal prognosis. The combination of H3K27M with BRAF V600 mutations rarely reported in DMG although more commonly in Paediatric-type low grade gliomas (Diffuse low-grade glioma, MAPK pathway-altered). We present a twenty-month-old boy, previously healthy, presented with 2 weeks history of unsteady gait, drooling, cranial nerves palsy MRI imaging showed diffuse pontine mass with classic radiological features of DIPG. 2.6 x 1.6 x 3.2 (AP x TV x CC) with no evidence for spinal metastases. Patient underwent right retro sigmoid approach and open biopsy of lesion he received focal Radiation Therapy 54GY/30fx as stander of care of DIPG with mild neurogical improvement Pathological & molecular Diagnosis was Diffuse midline glioma, H3 k27-altered with Co-occurrence BRAF V600E mutation. Two months after end of radiation, he presented with vomiting, and neurological deterioration with new right-side hemiplegia. Imaging studies showed interval increase in the pontine lesion with increased edema causing narrowing of the fourth ventricle, no active hydrocephalus. He was started on combination therapy BRAF inhibitor Dabrafenib and MEK Inhibitor Trametinib as maintenance therapy the patient gradually showed Marked neurological and clinical improvement. A 6-month MRI after start of targeted therapy showed favorable treatment response with complete resolution of the previous diffusion restriction, reduced tumor volume on MR perfusion ,reduced perilesional edema otherwise almost stabilization of nonenhancing pontine lesion. The poor prognosis of recurrent DIPG is well known but our patient is clinically and radiologically stable with excellent quality of life and well tolerating the therapy . Our case show that personalized treatment approach that address molecular heterogeneity of H3K27M glioma are safe and feasible
DIPG-37. Exploring the role of the epigenetic factor H2A.Z acetylation in DIPG
Authors: Sanguino Yolanda Colino , de la Fuente Laura Rodriguez , Kisswani Dana , Kearney Padraic , Jackson Evangeline , Duchatel Ryan , Holliday Holly , Jabado Nada , Tsoli Maria , Ziegler David , Dun Matthew , Mora Fatima Valdes
Published: June 2022

Diffuse intrinsic pontine glioma (DIPG) is the most aggressive brain tumor found in children with a peak incidence of 5-7 years of age, with median survival after diagnosis less than one year. In more than 60% of DIPG cases, a recurring somatic mutation in the H3F3A gene, that causes a lysine 27 to methionine substitution is seen in the histone variant H3.3 (H3.3K27M). Wildtype histone variants H2A.Z and H3.3, are frequently found in the same nucleosome and cooperate to regulate transcription. We and others have identified that acetylation of H2A.Z (H2A.Zac) can be an oncogenic driver in adult cancer types through mislocalization of H2A.Z at promoters and enhancers of cancer-associated genes loci. However, the role of H2A.Z in H3.3K27M+ DIPG has never been studied. Thus, we hypothesized that H2A.Zac cooperates with H3.3K27M to drive DIPG oncogenesis. Here we aim to unravel the molecular relationship between H2A.Zac and H3.3K27M in DIPG and their link to oncogenesis. First, using a histone mass spectrometry dataset, we found that the level of H2A.Zac is significantly higher in samples with H3K27M compared to H3.3WT. In addition, the comparison between H2A.Zac with H3.3K27M ChIP-seq data in several DIPG cell lines showed that around 30% of H3.3K27M peaks overlapped with H2A.Zac marked regions, a similar proportion found between H3.3 and H2A.Z under physiological conditions. Interestingly, active enhancers are the most enriched regulatory regions for H3.3K27M/H2A.Zac overlapping regions and those enhancers are associated with genes involved in pathways commonly altered in H3.3K27M gliomas. These data suggest H2A.Zac levels are altered in DIPG and H2A.Zac may be involved in aberrant enhancer activation in DIPG and thus constitute a novel therapeutic target for H3.3K27M+ DIPG.
DIPG-43. Glucosylceramide synthase inhibitors induce ceramide accumulation and sensitise H3K27 Mutant Diffuse midline Glioma to irradiation
Authors: Paret Claudia , Sandhoff Roger , Zahnreich Sebastian , Wehling Pia Charlotte , El Malki Khalifa , Faber Jörg
Published: June 2022

BACKGROUND AND AIMS: Glycosphingolipids (GSL) are amphipathic lipids particularly abundant in the brain where their amount and expression patterns change drastically during the embryonic to postnatal stages and during tumorigenesis. The biosynthesis of GSL begins with the formation of glucosylceramide from ceramide, a step catalysed by the glucosylceramide synthase (UGCG). UGCG can be inhibited by eliglustat, which is used for treating children with Gaucher‘s disease. We have previously shown that the GSL composition is deregulated in H3K27M mutant diffuse midline glioma (H3K27M mut) and that eliglustat inhibits cell proliferation. Here we analysed the mechanism of action of eliglustat in H3K27M mut and its effect on irradiation. METHODS: The concentration of different components of the sphingolipid metabolism (ceramide, ceramide-1-Phosphate (CIP), sphingomyelin, Sphingosine and Sphingosine-1-Phosphate (S1P)) was assessed by mass spectrometry in the H3K27M mut cell line SF8628, before and after treatment with eliglustat. The combination of eliglustat with ionizing radiation was analysed by clonogenic assay. RESULTS: The treatment of H3K27M mut cells with eliglustat resulted in a significant increase in the concentration of ceramide, Sphingosine, C1P, but not S1P. The increase was concentration and time dependent and was not observed after longer incubation. Eliglustat treatment reduced the colony formation ability after irradiation. CONCLUSIONS: Ceramide is a known mediator of apoptosis involved in the molecular mechanisms underlying cellular response to irradiation. Increased endogenous ceramide levels, induced by blocking the synthesis of GSL, may sensitize H3K27M mut cells to irradiation. However, ceramide can be converted in C1P, a potent inhibitor of apoptosis and inducer of cell survival. Thus, the time and concentration dependent shift to ceramide and C1P requires further investigation in order to achieve an appropriate balance between the levels of these two metabolites and identify the optimal therapeutic window for combination with irradiation and potentially chemotherapy
DIPG-56. Development and application of a novel antibody against CD99 as a therapeutic strategy in Diffuse Midline Glioma
Authors: Venkataraman Sujatha , Balakrishnan Ilango , Madhavan krishna , Chetty Senthilnath Lakshmana , Pierce Angela , Fosmire Susan , Nuss Zachary , Coleman Philip , Green Adam , Vibhakar Rajeev
Published: June 2022

BACKGROUND: There is an unmet need to identify novel targeted therapies for Diffuse Midline glioma (DMG) which is currently a refractory disease. Recently, we identified high expression of a cell surface antigen, CD99 in H3K27M-mutant expressing DMGs compared to other normal brain counterparts. We developed a novel chimeric CD99 antibody and tested the anti-tumor efficacy of this antibody in vitro and in vivo. METHOD: Bio-legend cell-surface screening was performed in H3K27M-mutant and WT DMG cells. Functional role of CD99 was studied using CD99 proficient and depleted tumors. Designed and synthesized CD99 antibody with a new binding sequence on a human IgG scaffold and performed cell toxicity and growth-inhibitory studies using DMG tumor and normal cells. We also performed these studies in combination with radiation. Multiple patient-derived orthotopic DMG xenograft models was used to test the antibody efficacy. Different antibody delivery routes, that are clinically relevant were investigated. RESULTS: CD99 expression is transcriptionally regulated by H3K27M and is enriched on the cell surface of K27M tumors compared to WT DMG tumors. Our new CD99 antibody (10D1 clone) significantly reduced DIPG tumor cell proliferation in vitro. Intravenous infusion of this antibody in DIPG tumor bearing mice showed complete clearance of tumor that prolonged animal survival suggesting the enhanced anti-tumor efficacy of 10D1-CD99 and importantly, its ability in crossing the blood-brain-barrier and reaching the pons target site. Loco-regional administration of 10D1 showed similar anti-tumor effects even at much reduced antibody concentrations while toxicity to CD99-expressing T cells was minimum. Radiation increased CD99 expression and enhanced the cytotoxic effect of 10D1-CD99. CONCLUSION: We have developed a novel CNS penetrant CD99 antibody that is an attractive therapeutic strategy in treating DMG. 10D1 is currently in development as a therapeutic.
DIPG-62. Reducing the levels of genomic 5-hydroxymethylcytosine by inhibiting the TET pathway induces apoptosis and decreases proliferation in Diffuse Intrinsic Pontine Glioma (DIPG)
Authors: Parthasarathy Akhila , Arnold Antje , Eberhart Charles , Raabe Eric
Published: June 2022

The H3K27M mutation, observed in 70%-90% of DIPG, causes global hypomethylation. The Ten-Eleven-Translocation enzymes, TETs, which convert 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC) regulate the methylation patterns in the genome. Previously, we observed an increase in the 5hmC levels and altered TET activity in DIPG. We hypothesize that targeting the TETs in DIPG could restore the epigenetic balance. In this study, we target the TET pathway with cell-permeable 2-hydroxyglutarate (2HG) and Bobcat339, a cytosine-based TET inhibitor. We see a dose-dependent decrease in 5hmC (46-96% reduction) and increase in 5mC (~5fold increase) in multiple DIPG cell lines treated with 2HG. We see a corresponding increase in apoptosis and reduction in proliferation (~8fold increase in cleaved-Caspase3 signal (P=0.0001) and ~55% reduction in BrdU-incorporation measured by IF (P=0.0036) in JHH DIPG16A with similar results in JHH DIPG1, HSJD007, and SUDIPG6). We see a 54-90% reduction in 5hmC and ~3fold increase in 5mC with Bobcat 339 treatment in DIPG cell lines JHH DIPG1, JHH DIPG16A, HSJD007, and SUDIPG6. We also see a corresponding increase in apoptosis as measured by cleaved PARP western blot and decrease in proliferation as measured by BrdU incorporation (approximately 32-53% decrease in proliferation). Combined treatment with 2HG and Bobcat339 lead to greater decreases in 5hmC and increases in 5mC compared to single treatment, with synergistic suppression of cell growth as measured by SynergyFinder in HSJD007, JHH DIPG1, and JHH DIPG16A. In vivo studies targeting DIPG orthotopic xenografts are currently underway. These results suggest that TETs contribute to the hypomethylated state observed in DIPG. Thus, inhibiting the TETs can be explored as a potential therapeutic approach to treat DIPG.
DIPG-63. Therapies for diffuse gliomas in pediatric patients: a systematic review and meta-analysis
Authors: Paracha Awais , Abdelbaki Mohamed S , Navalkele Pournima
Published: June 2022

Diffuse gliomas are one of the most challenging pediatric brain tumors of the current era. The new WHO classification has brought in a paradigm shift in the diagnosis and management of diffuse gliomas. Although these tumors are not surgically resectable, an integrated molecular analysis could make them more amenable to targeted agents. We conducted a thorough systematic review and meta-analysis of therapies for diffuse gliomas in pediatric patients. Methods: Using PRISMA guidelines, PubMed, (Medline), Cochrane, and Google Scholar database searches are being conducted using search terms “diffuse midline glioma”, “diffuse midline astrocytoma” and “diffuse glioma management”. PubMed search filters used to find relevant articles were “human” species, “English” language, and “age birth to 18 years”. Results: Interim analysis using the PubMed database has revealed 387 articles of which 32 articles describe details of therapies used in pediatric patients. We found 8 case reports, 17 case series, and 7 clinical trials elucidating therapies for diffuse gliomas. Comprehensive analysis of modalities of therapies including neurosurgery, chemotherapy, and radiation therapy, along with survival analysis for these patients stratified by H3.3K27M mutant status is ongoing.