bluuebunny/crossref_metadata_2025 huggingface dataset:
EPEN-32. Leveraging cell surface targets as therapeutic vulnerabilities for pediatric ependymoma
Authors: Bertrand Kelsey
Published: June 2022

Brain tumors are the leading cause of cancer-associated death in children. Ependymoma, an aggressive type of childhood brain tumor, is currently treated with surgery and radiotherapy. Ependymomas are a molecularly heterogeneous group of tumors driven by distinct genetic and epigenetic alterations. In children, 90% of ependymomas arise intracranially, with two thirds occurring in the posterior fossa (PF) and one third in the supratentorial brain (ST). PF ependymomas are divided into at least two groups termed, PFA and PFB, with PFA tumors associated with poor clinical outcomes. Over 70% of ST ependymoma are characterized by an oncogenic fusion between ZFTA and RELA and shown in some cohorts to have poor clinical outcome, particularly in the context of CDKN2A tumor suppressor gene loss. A major challenge in identifying therapies against ependymoma, has been the paucity of genetic abnormalities available for targeting. PFA ependymomas harbor largely balanced genomes with no recurrent CNVs, fusions, or somatic mutations that are amenable to pharmacologic inhibition. ZFTA-RELA ependymoma while representing a clear disease driver, functions as a transcription factor and lacks clear binding surfaces available for direct inhibition using small molecules. Therefore, alternative approaches are needed to identify new targets and effective therapies in ependymoma to be evaluated in pre-clinical models. In both human ependymoma cell culture lines and PDX models, we demonstrate that a multi-omic approach is promising for cell surface target discovery, and further, focused cell surface profiling can identify lead targets that can be rapidly translated for CAR T-cell therapy.
EPID-01. Differences in first-line treatment but comparable survival outcomes for pediatric brainstem and non-brainstem high-grade gliomas in the Netherlands – a population-based study
Authors: Hoogendijk Raoull , van der Lugt Jasper , Baugh Josh , Kremer Leontien , Hoving Eelco , van Vuurden Dannis , Karim-Kos Henrike
Published: June 2022

INTRODUCTION: Pediatric high-grade gliomas (pHGG) are among the most devastating childhood cancers. Due to their limited treatment options and tumor biology, brainstem (BS) pHGG are considered to have worse survival outcomes compared to non-brainstem (NBS) pHGG. METHODS: Detailed clinical data were gathered by trained registrars for all children diagnosed with a pHGG (including radiologically diagnosed brainstem tumors) in the Netherlands for the period 2003-2017. Tumors were grouped into BS and NBS tumors according to the ICD-O-3 topography codes. Differences in treatment characteristics were tested with the Chi-squared, Fisher exact or Mann-Whitney-Wilcoxon test. Median survival time was determined by Kaplan-Meier method. Trends and survival differences were tested with Cox Proportional-Hazards Models. RESULTS: In total, 276 pHGG patients (BS n=166, NBS n=110) were diagnosed during 2003-2017. Differences in first line treatment were found for neurosurgery (25% of BS versus 95% of NBS patients, p<0.001) and systemic therapy (20% of BS versus 70% of NBS, p<0.001). Notable, 10% of BS patients received temozolomide compared to 55% of NBS patients (p<0.001). No significant difference was found for first-line radiotherapy. However, total cumulative dose and number of fractions differed significantly (BS: median 44.8 Gy and 16 fractions; NBS: median 57.4 Gy and 30 fractions, both p<0.001), reflecting hypofractionation regimens in BS pHGG. Survival remained stable over time for both BS (p=0.9) and NBS (p=0.3). Median survival time was comparable between BS (9.7 months) and NBS patients (9.8 months, p=0.6).CONCLUSION: Despite differences in treatment characteristics we found comparable survival outcomes for BS and NBS pHGG. It remains unclear why survival for both BS and NBS pHGG in this retrospective population-based study is substantially inferior to published data. If the underlying reasons can be found in differences in treatment characteristics, data type (hospital-based versus population-based) or incompleteness of non-microscopically verified cases, is subject to further research.
EPID-02. Survival Experience in Pediatric Patients of Central Nervous System (CNS) Tumour in Canada
Authors: Yuan Yan , Liu JiaQi , Walker Emily , Davis Faith
Published: June 2022

Established in 2016, the Brain Tumour Registry of Canada Surveillance Research Collaboration aims to address the lack of detailed information on CNS tumours in Canada. Using Canadian Cancer Registry (CCR) data with linked vital status, we present survival estimates for all primary CNS tumours (excluding Quebec) among pediatric patients (age 0-14). Pediatric patients diagnosed with primary CNS tumours during 2010-2017 were included. Vital status was obtained by Statistics Canada through linkage to the Canadian Vital Statistics Database and the income tax returns file, with a cut-off date of December 31, 2017. We used the Pohar-Perme method to estimate the net survival rate (NSR) through the period approach. International Classification of Diseases for Oncology (3rd edition) site/histology codes were grouped into 25 histological categories, irrespective of tumour behaviour, according to the schema developed by the Central Brain Tumor Registry of the United States. Of 1725 pediatric CNS tumours, the 1-, 2- and 5-year NSR are 0.89 (95%CI 0.87-0.90), 0.84 (95%CI 0.81-0.86) and 0.80 (95%CI 0.78-0.82), respectively. All non-malignant CNS tumours have a median survival over 8 years. The 5-year NSR range from 0.90 (95%CI 0.47-0.99) for unique astrocytoma variants, 0.95 for tumour of sellar region (95%CI 0.85-0.98) and germ cell tumours, cysts and heterotopias (95%CI 0.67-0.99), to 1.0 for choroid plexus tumours, tumours of cranial and spinal nerves, and meningioma. For malignant CNS tumours, NSR vary greatly depending on histology grouping. 5-year NSR from lowest to highest are glioblastoma (0.10, 95%CI 0.03-0.23), anaplastic astrocytoma (0.19, 95%CI 0.05-0.40), glioma not otherwise specified (0.54, 95%CI 0.46-0.62), embryonal tumours (0.72, 95%CI 0.65-0.79), diffuse astrocytoma (0.74, 95%CI 0.59-0.85), ependymal tumours (0.78, 95%CI 0.67-0.87), germ cell tumours, cysts and heterotopias (0.85, 95%CI 0.70-0.93) and pilocytic astrocytoma (1.0). We report the most comprehensive and up-to-date data on the pediatric primary CNS tumour survival experience in Canada.
EPID-06. Transfusion related iron overload in pediatric patients with CNS tumors
Authors: Winzent-Oonk Shelby , Winters Amanda , Pounds Aneisia , Pacenta Holly , Levy Jean Mulcahy , McKinney Christopher
Published: June 2022

BACKGROUND: Patients receiving chemotherapy or autologous hematopoietic stem cell transplant (autoHSCT) routinely receive red cell transfusions as supportive care. Each unit of transfused red cells contains approximately 150mg of iron which the body has no natural mechanism for excreting. Transfusion-related iron overload (TRIO) is an under-recognized complication of therapy which left untreated may result in long-term damage to the liver, heart, or endocrine organs. We sought to identify the prevalence of TRIO in patients with pediatric CNS tumors and evaluate specific risk factors. METHODS: A retrospective record review of pediatric CNS tumor patients treated at Children’s Hospital Colorado was conducted including patients who completing therapy between 1/1/2014 – 12/1/2021. Patients at high risk for TRIO were defined as having a cumulative transfused blood volume of more than 150mL/kg or 4000mL total. The diagnosis of TRIO was confirmed if patients had a serum ferritin greater than 1000ng/mL or elevated liver iron content of 7mg/g dry weight or greater by MRI. RESULTS: There were 173 evaluable patients (40% embryonal tumors, 15% germ cell tumors, 10% ependymomas, 26% low grade gliomas, 5% high grade gliomas, and 3% other tumors). The mean age at completion of therapy was 8 years (range: 0.67 – 25 years). Patients receiving autoHSCT (24% of cohort) were at higher risk for TRIO based on transfused volumes (p<0.0001) than patients not treated with autoHSCT (72% vs 6%, RR 12.0) The prevalence of TRIO in autoHSCT patients was 7.5% (3/40) vs 0.8% (1/121) in patients not undergoing autoHSCT (RR 9.37). For autoHSCT patients at high risk by transfused volume the prevalence of TRIO was 10.3% (3/29). CONCLUSIONS: Pediatric CNS tumor patients who have received an autoHSCT are at higher risk for TRIO than those who have not. Routine screening for TRIO should be offered to patients receiving autoHSCT.
EPID-07. Outcome disparities in children, adolescents and young adults with medulloblastoma: A population-based analysis
Authors: Genecin Isabel , Fullwood Dottington , Moisander-Joyce Hanna , Padilla Oscar , Minns Hanna , Garvin James , Szalontay Luca , Wu Cheng-Chia , Kahn Justine , Gartrell Robyn D
Published: June 2022

Medulloblastoma (MB) is the most common high-grade primary pediatric brain tumor. Recent registry-based studies in children with central nervous system (CNS) tumors have demonstrated that survival outcomes differ by race/ethnicity in multivariable analyses, with Hispanic patients having highest hazard of death overall. To investigate this finding in MB patients, we examined survival in children (0-14 years) and adolescent/young adults (15-39 years) with MB from 2007-2016 in the 2018 Surveillance Epidemiology and End Results Program database, using Kaplan Meier analysis, log-rank test and Cox proportional hazard ratios (HR) with 95% confidence intervals (CI). Race and ethnicity were categorized according to the U.S. Census, with Hispanic ethnicity (yes/no) analyzed separately from race (Black, White, Asian, Other). Among 1612 patients, 81% were White, 9% were Black, 8% were Asian or Pacific Islander, and 2% were from “other” or unknown racial groups. 28% of the cohort was of Hispanic ethnicity. Univariate analysis found that Black patients had a significantly higher hazard of death than White patients (HR=1.55, CI: 1.16 – 2.08, p=0.003). In contrast, Hispanic ethnicity was not significantly associated with outcome (HR=0.98, CI: 0.79-1.21, p=0.8). Medicaid or no insurance (vs. private) were each significantly associated with higher risk of death; Medicaid (HR =1.23, CI = 1.01 - 1.51, p=0.041); Uninsured (HR=2.07, CI=1.41-3.02, p=<0.001). Of the treatment modalities analyzed, patients who received neither chemotherapy nor radiation experienced higher hazard of death than patients who received both treatments (HR=3.63, CI 2.78-4.76, p=<0.001). Consistent with observations in other cancers, racial disparities are observed in patients with MB, with Black race conferring increased risk of death. Public insurance was also significantly associated with death, as was not receiving combined-modality therapy. Further work is needed to understand the multilevel factors impacting diagnosis, treatment and outcome among children and AYAs with MB and prospective studies are warranted.
ETMR-08. Treatment strategy for pineoblastoma in infant
Authors: Suzuki Mario , Shimizu Yuzaburo , Akiyama Osamu , Fujimura Junya , Kondo Akihide
Published: June 2022

Pineoblastoma is a rare malignant brain tumor that occurs in infancy and young adulthood. Although its prognosis has improved in recent years, it remains one of the difficult tumor types to treat. We will retrospectively review the treatment of pineoblastoma at our hospital and propose the possibility of a new treatment for this tumor type. Three cases were studied. All of them presented at less than three years of age and were treated for hydrocephalus simultaneously as the biopsy. Chemotherapy was administered after a possible resection, and local radiotherapy was administered at the age of 3 years. Overall survival ranged from 7 to 91 months, with one case of long-term survival. To date, the prognostic factors for pineoblastoma are the age of onset and the presence of radiation therapy. This is interpreted to mean that the prognosis is worse in infants and young children who cannot be immediately treated with radiation therapy, indicating that radiation therapy is essential for treating this tumor type. On the other hand, radiation therapy for infants can significantly interfere with the development of the central nervous system, and there is much controversy about its potential compatibility with tumor control. We have identified a favorable prognosis group based on the molecular biological background of this tumor type. We propose that early radiotherapy may improve the prognosis.
ETMR-09.In vitro modelling of embryonal tumors with multilayered rosettes (ETMR) and other novel brain tumor types.
Authors: Bunt Jens , Roosen Mieke , Stathi Phylicia , Polychronopoulos Panagiotis , Odé Zelda , Maas Joris , Kool Marcel
Published: June 2022

Over the last decade, molecular characterization has resulted in many tumors previously classified as central nervous system primitive neuroectodermal tumors (CNS-PNETs) now being classified into their own distinct tumor types. These novel types are often characterized by very specific genomic aberrations. For instance, embryonal tumors with multilayered rosettes (ETMR) harbor amplifications of miRNA cluster C19MC or complex DICER1 mutations, while in CNS neuroblastoma with FOXR2 activation structural aberrations result in aberrant FOXR2 expression. Despite the presence of distinct oncodrivers, our understanding of these tumors is still limited. To elucidate tumor biology and to discover tumor specific treatments, we need to uncover how these oncodrivers contribute to tumorigenesis. However, a bottleneck in basic and translational research of these novel tumor types, is the lack of representative preclinical models, especially in vitro. To overcome this hurdle, we aim to mimic tumor development in genetically modified brain organoids. Human brain organoids derived from pluripotent stem cells are generated to represent either the developing forebrain or cerebellum. To mimic oncodriving events, DNA plasmids are introduced via electroporation into the proposed cell-of-origin populations to knockout tumor suppressor genes or overexpress oncogenes. By detecting fluorescent proteins encoded by the plasmids, electroporated cells are followed over time. Based on our preliminary data, for instance, overexpression of C19MC results in ectopic expansion of the electroporated cells. Ongoing histological and molecular characterizations, including (single cell) transcriptomic and epigenomic analyses, will reveal to which extend these organoid models resemble the specific human tumor types. Although further validation is required, these organoid models provide a novel avenue to study especially brain tumor types with distinct oncodriving events for which patient-derived models have not yet been established. They also allow for in-depth analyses of the potential cells of origin and the contribution of different mutations to tumor biology.
ETMR-12. Novel cell models of CNS tumors with BCOR fusion or internal tandem duplication suggest FGFR and PDGFR as promising therapy targets
Authors: Kirchhofer Dominik , Lötsch-Gojo Daniela , Gabler Lisa , Jaunecker Carola N , Piontek Martin , Mayr Lisa , Englinger Bernhard , Pirker Christine , Mohr Thomas , Lämmerer Anna , Schmitt-Hoffner Felix , Boidol Bernd , Kubiceck Stefan , Peyrl Andreas , Azizi Amadeo A , Dorfer Christian , Haberler Christine , Kool Marcel , Berger Walter , Gojo Johannes
Published: June 2022

Central nervous system (CNS) tumors with BCOR internal tandem duplications (CNS-BCOR ITD) are aggressive malignancies recently included in the 2021 WHO Classification of CNS tumors. This entity is characterized by ITDs within the PUFD domain of BCOR, potentially interfering with protein-protein interactions and preventing non-canonical polycomb repressive complex 1.1 (ncPRC1.1) complex formation. Additionally, other BCOR alterations like frame shift mutations and gene fusions have been described. However, the underlying molecular mechanisms promoting tumor aggressiveness remain unknown. We established cell models from one patient harboring a BCOR frameshift mutation and another one with a concomitant BCORL1-fusion. Two additional models were derived from a patient with a CNS-BCOR ITD tumor. Multidrug screening uncovered high sensitivity against defined receptor tyrosine kinase (RTK) inhibitors (TKIs). In detail, ponatinib, nintedanib, and dovitinib reduced cell viability at half maximal inhibitory concentrations (IC50) in the low micro-molar range (<2.5 µM). Expression analyses of the respective TKI targets suggested fibroblast growth factor receptor 3 (FGFR3) and platelet derived growth factor receptor A (PDGFRA) as central players in this response. RTK inhibition resulted in strongly impaired downstream MAPK and Pi3K/AKT signaling. Vice versa, exposure to the RTK ligands bFGF and PDGFAA increased S6, Erk and Akt phosphorylation. Next, we treated two patients – one with a BCOR frame shift mutation/BCORL1-gene fusion and one with an ITD with nintedanib – within a multimodal treatment approach and achieving complete remission and disease stabilization, respectively. Ultimately, we analyzed respective RTK ligands in patient cerebral spinal fluid (CSF) and found FGF18 and PDGFA to correlate with tumor treatment response and progression. Summarizing, we uncover a central role of defined RTK signaling modules in the malignant phenotype of CNS-BCOR-ITD and tumors harboring BCOR alterations and elucidate their potential as therapeutic targets. Currently, we aim to dissect the interconnection between BCOR/BCORL1 alterations and RTK hyperactivation.
ETMR-14. The single-cell landscape of pineoblastoma identifies developmental origins and exposes novel therapeutic vulnerabilities.
Authors: Gudenas Brian , Englinger Bernhard , Liu Anthony P Y , Ahmad Sheikh Tanveer , Meredith David , Pfaff Elke , Paul Leena , Hadley Jennifer , Batts Melissa , Klimo Paul , Boop Frederick A , Gajjar Amar , Robinson Giles , Orr Brent , Lin Hong , Alexandrescu Sanda , Jones David T W , Filbin Mariella G , Northcott Paul A
Published: June 2022

Pineoblastoma (PB) is a rare and aggressive childhood brain tumor with highly variable age and treatment-associated outcomes. Our recent bulk tumor analyses of DNA methylation and mutational landscapes uncovered four discrete PB molecular subgroups (PB-miRNA1, PB-miRNA2, PB-MYC/FOXR2, and PB-RB), providing a major advance in our understanding of biological and clinical heterogeneity. However, developmental origins of PB subgroup heterogeneity and mechanisms governing how specific genetic alterations promote malignancy remain unknown. To resolve the cellular origins of PB, we assembled a large single-nucleus RNA-sequencing cohort (n=32) of primary PB tumors, including representatives from each subgroup. Transcriptomic analysis identified subgroup-specific gene expression programs driving intra-tumoral heterogeneity. In addition, we discovered substantial differences in the expression of miRNA biogenesis genes between the PB-miRNA1 and PB-miRNA2 subgroups, providing mechanistic support for their distinct subgroup identities despite overlapping driver events. The MYC/FOXR2 subgroup was characterized by over-expression of the FOXR2 proto-oncogene in bulk RNA-seq, which we validated in single-nuclei and identified co-expressed downstream target genes. To map PB subgroups to their putative developmental beginnings, we created a single-cell transcriptional atlas of the murine pineal gland across 11 developmental stages (E11-P21). Trajectory inference within the developing pineal gland revealed a differentiation continuum of early, mid, and mature alpha-/beta pinealocytes. Cross-species correlation and deconvolution identified significant associations between multiple PB subgroups and specific differentiation states of the pinealocyte lineage, suggestive of developmental origins. Characterization of pinealocyte development informed generation of biologically faithful disease models, including a novel genetically engineered mouse model of the PB-RB subgroup. PB-Rb1 mouse tumors were histologically and molecularly validated for their fidelity to human tumor counterparts, exhibiting up-regulation of key pinealocyte lineage markers that are diagnostic in patients. Finally, high-throughput drug screening identified several promising pharmacological candidates that may attenuate consequences of Rb1 deficiency in affected children.
ETMR-16. Embryonal tumors with multi-layered rosettes: A case series in treatment for newly diagnosed children
Authors: Tran Hung , Margol Ashley , Cotter Jennifer , Szymanski Linda , O’Halloran Katrina , Tamrazi Benita , Michaiel George , Christian Eisha , Esfahani Darian , Davidson Tom Belle
Published: June 2022

BACKGROUND: Embryonal tumors with multi-layered rosettes (ETMRs) are rare pediatric brain tumors with poorly defined prognostic features, standard of care treatments or outcome data. Recent data suggest that high-dose chemotherapy and radiotherapy is correlated with improved survival compared to chemotherapy alone. CASE DESCRIPTIONS: Four patients with newly diagnosed ETMRs were treated with 2 cycles of induction chemotherapy per PBTC-026 using isotretinoin, vorinostat, vincristine, cisplatin, etoposide, cyclophosphamide with added intrathecal topotecan. Second look surgery was performed if not in complete remission (CR). Consolidation was with three cycles of marrow-ablative chemotherapy (carboplatin and thiotepa) with autologous hematopoietic cell rescue followed by focal irradiation and 12 cycles of maintenance chemotherapy with intrathecal topotecan, vorinostat and isotretinoin. Patient 1 was a 3-year-old female with right parietal tumor, localized, and achieved gross total resection (GTR). Patient 2 was an 11-month-old male with posterior fossa tumor, localized, and achieved subtotal resection. Patient 3 was a 9-month-old female with posterior fossa tumor with near GTR, and metastasis to T12/L1 and L3/L4. [DTB1] [HNT2] Patient 4 was a 34-month-old male with a right frontal lobe tumor, localized and achieved GTR. Patient 1 is now 18 months from diagnosis and in CR. Patient 2 had second look surgery both after induction and consolidation but suffered neurologic injury to the brainstem which led family to decline further therapy. He is currently 14 months from diagnosis with stable residual disease. Patient 3 had local disease recurrence following radiation therapy at 10 months post diagnosis[DTB3] [HNT4] , prior to maintenance. Patient 4 remains in CR at 13 months from diagnosis, currently in maintenance with vorinostat and isotretinoin but declined intrathecal topotecan. CONCLUSION: This case series adds to current knowledge of intensive multi-modal therapy for newly diagnosed ETMR. Further study to define standard optimal treatments in this high-risk group of patients is warranted.
GCT-06. Management of a congenital intracranial teratoma: a case report and review of literature
Authors: Shatara Margaret , Cantor Evan , Ramos Kristie N , Yu Jonathan , Hassan Ahmad , Shimony Joshua S , Han Peng Cheng , Meyer Ashley , Ogle Andrea , McHugh Michele , Green Tammy , Beck Mary , Cluster Andrew , Brossier Nicole , Rubin Joshua , Dahiya Sonika , Abdelbaki Mohamed S , Strahle Jennifer
Published: June 2022

INTRODUCTION: Congenital intracranial teratomas (CITs) are rare tumors occurring in the first 60 days of life, often associated with dismal prognosis, posing challenges in both oncologic and surgical management. METHODS: We report a patient with a congenital mature teratoma diagnosed prenatally, who underwent successful surgical resection following neoadjuvant chemotherapy. We also performed an updated literature review on CIT outcomes. RESULTS: A newborn female, diagnosed prenatally with a complex midline intracranial echogenic mass, underwent postnatal brain MRI which demonstrated a supratentorial large complex enhancing mass with solid and cystic components, with associated obstructed hydrocephalus. Serum alpha-fetoprotein (AFP) and beta-human chorionic gonadotropin were normal for age. Tumor biopsy revealed mature teratoma. AFP obtained from cyst fluid during fenestration was significantly elevated at 8 weeks of life. Due to concerns for possible malignant transformation and in an attempt to alter tumor vascularity facilitating surgical resection, the patient received two cycles of neoadjuvant carboplatin and etoposide, followed by tumor resection without significant intraoperative bleeding. There was no evidence of immature components on final pathology. The patient remains without tumor recurrence, now 9 months, since surgical resection. Review of literature yielded 76 cases of CITs: eight patients with mature teratoma, of which six remained alive following tumor resection. Five patients with immature teratoma received chemotherapy prior to resection; three remained alive post-resection (follow-up range 3-20 years). DISCUSSION: CITs are typically associated with poor prognosis, with reported one-year survival of 7.2-12%. Surgical excision is the mainstay of treatment, often limited by intraoperative hemorrhage. Neoadjuvant chemotherapy has been employed as a successful strategy to reduce tumor volume and vascularity in a variety of pediatric brain tumors; more specifically, carboplatin and etoposide are utilized as neoadjuvant chemotherapy for non-germinomatous germ cell tumors to facilitate excision in older children. Their role in CITs requires further evaluation.
GCT-09. Transcriptome and methylome profiles of CNS germ cell tumors and their comparison with testicular counterpart
Authors: Takami Hirokazu , Elzawahry Asmaa , Mamatjan Yasin , Kato Mamoru , Hama Natsuko , Shibata Tatsuhiro , Nakazato Yoichi , Nishikawa Ryo , Matsutani Masao , Ichimura Koichi
Published: June 2022

BACKGROUND: The pathophysiology of CNS germ cell tumors (GCTs) has yet to be fully unraveled, resulting in the paucity of treatment options. The biological comparison with its testicular counterpart has not been interrogated. METHODS: In total, 84 cases of CNS GCT were investigated for methylation and transcriptome analyses, and an integrative analysis of the normal cells undergoing embryogenesis and testicular GCTs was conducted. RESULTS: Transcriptome analysis revealed germinoma and non-germinomatous GCTs (NGGCTs) were clearly separated. On transcriptome, germinoma was characterized by primitive cell state, closely related to primordial germ cell (PGC) with meiosis/mitosis potentials. NGGCT had a feature of more differentiated cell state directed toward organogenesis. Germinoma was subdivided into two clusters on integrated transcriptome and methylation analysis, and they are different in the age distribution and tumor cell content. CNS and testicular GCTs were divided based on histology, either germinoma/seminoma or NGGCT/non-seminomatous GCTs on methylation. Expression analysis mainly clustered them depending on the site of origin and histology. CONCLUSIONS: Expression profiles of CNS GCTs distinctly reflect the histological variabilities. Germinoma may be clustered into two groups, with possible differentiation in treatment intensity in the future. GCTs at CNS and gonads seem to have a mutual cell-of-origin and similar genomic backgrounds, which potentiates site-agnostic treatment development.
GCT-14. The Impact of Residual Disease on the Outcomes of Central Nervous System Germinomas – A Single Institution Experience
Authors: Cantor Evan , Cochrane Anne , Ogle Andrea , Meyer Ashley , Brossier Nicole M , Shatara Margaret , Cluster Andrew , Abdelbaki Mohamed S
Published: June 2022

BACKGROUND: CNS Germinomas are highly radio-sensitive tumors with an excellent survival rate of more than 90%. The current standard of care combines chemotherapy with reduced-dose radiotherapy to minimize the adverse effects and long-term effects associated with radiotherapy. In the latest Children’s Oncology Group clinical trial (ACNS1123 stratum 2), patients with residual or progressive disease following chemotherapy can be considered for a “second-look” surgery to assess tumor viability. Patients with residual disease who do not undergo second-look surgery receive 24 Gy of whole ventricular radiation with a 12 Gy boost compared to 18 Gy plus boost given to patients in complete remission or without viable tumor on second-look. Conversely, the International Society of Paediatric Oncology (SIOP) protocol does not stratify based on response to chemotherapy, and the Korean SMC GCT trial uses 18 Gy CSI plus boost for all patients regardless of chemotherapy response. METHODS: Single center retrospective chart review of germinoma patients treated at St Louis Children’s Hospital between 2011 and 2021. RESULTS: We analyzed data for all 15 germinoma patients treated between 2011 and 2021. Five patients had residual disease following chemotherapy. Of these five, one had complete remission at the end of radiotherapy, one had partial response, and three had stable disease. All patients remain relapse-free with time of follow-up ranging between 6.3-109.3 months from the end of therapy (median 24 months). CONCLUSION: None of the five patients with residual disease following chemotherapy demonstrated disease progression following chemotherapy and radiotherapy. Future prospective clinical trials are needed in order to test the possibility of treating germinomas patients who have residual disease after chemotherapy with a low dose of radiotherapy similar to that used in patients with complete remission.
GCT-17. Recurrence of CNS germ cell tumors (GCTs) along biopsy and ventriculostomy tracts
Authors: McGlynn Mary Claire , Drogosiewicz Monika , Reiners Stephanie , Abdelbaki Mohamed
Published: June 2022

BACKGROUND: Central nervous system (CNS) germinoma relapses are rare. However, the latest Children’s Oncology Group (COG), ACNS1123 stratum 2, described three relapses along the biopsy tract out of eight total relapses; two along the biopsy and endoscopic third ventriculostomy (ETV) tract and one along the biopsy tract and external ventricular drain. Given these findings, we sought to describe other cases of GCT recurrence along surgical tracts. METHODS: We performed a literature review from 1980-2021 to identify cases of GCT recurrence along biopsy and ventriculostomy tracts. RESULTS: Three patients with pineal lesions were identified (13, 14, and 34-years old). All underwent ETV, cerebrospinal fluid (CSF) sampling, and tumor biopsy. Two patients had uncomplicated postoperative courses. One developed persistent hydrocephalus and underwent repeat ventriculostomy. Two were diagnosed with pure germinoma and treated with focal radiotherapy of 45 Gy alone or chemotherapy and radiation (50.4 Gy to the tumor volume and 36 Gy to adjacent high-risk area). The third was treated with methotrexate and corticosteroids. All three had recurrence on surveillance MRI (1-3 years after diagnosis). One had recurrence at the ventriculostomy bur hole site, and two had recurrence along the ventriculostomy tract. On biopsy, all three lesions were germinomas. One received pre-radiation chemotherapy and palliative radiation (36 Gy to surgical bed and 30.6 Gy to surrounding high-risk area). Another received chemotherapy and craniospinal radiation of 15 Gy. The third had a complicated post-biopsy course. He ultimately underwent chemotherapy and radiation (24 Gy). All were still alive at time of report. Two were disease free at 12 and 18 months, while one was still receiving chemotherapy. CONCLUSION: Recurrence along the biopsy or ventriculostomy tract is rarely reported in the literature. Future evaluation to determine the incidence could inform if biopsy and ventriculostomy tracts should be included in the radiation therapy field.
GCT-21. Long-term outcome and follow up of intracranial germ cell tumors: Reduced-dose radiotherapy and intensified chemotherapy improves clinical outcome and quality of life for long-term survivors
Authors: Kagawa Naoki , Miyamura Takako , Yamasaki Kai , Hirayama Ryuichi , Kijima Noriyuki , Okita Yoshiko , Nakagawa Tomoyoshi , Hara Junichi , Kishima Haruhiko
Published: June 2022

BACKGROUND: Intracranial germ cell tumors (iGCT) are heterogeneous tumors with several histopathology. Chemoradiotherapy is effective and required for treatment against them, but optimal treatment intensity should be selected from the viewpoint of both improvement of clinical outcome and avoidance of late complications. We introduced a protocol with reduced-dose radiotherapy and intensified chemotherapy for iGCT. OBJECTIVE: We retrospectively analysed the clinical outcome, especially for non-germinomatous germ cell tumors and long-term clinical outcome of late complications, enrollment and employment, as indicators of quality of life (QOL). MATERIALS AND METHODS: Thirty-eight children and young adults (28 men and 10 women) with iGCTs treated in our institution from 1997 to 2013 were enrolled in this study. They consisted of 26 germinomas including HCG-producing cases and 12 non-germinomatous GCTs (NGGCT). Local irradiation was selected for all patients, and the dose of irradiation was 23.4-54 Gy. The whole-brain irradiation was made in patients who had intracranial dissemination, but any prophylactic irradiation to the whole brain and spinal cord was not performed. For NGGCT, high-dose chemotherapy and peripheral blood stem cell transplantation (PBSCT) were introduced. Second-look surgeries were performed for cases with residual tumors after induction chemotherapies. RESULTS: In germinoma group and NGGCT group, 10-year progression-free survival was 86% and 84%, 10-year overall survival was 93% and 91%, respectively. About late complications, endocrinological replacement (39%), cerebrovascular disease such as cavernous hemangioma and arterial stenosis (18%), secondary neoplasm (2.6%) were observed. Regarding QOL, enrollment and return to school rate was 92% and employment and the return rate was 89%, which were influenced by hemipararesis associated with basal ganglia lesion, intractable epilepsy and whole-brain irradiation. CONCLUSION: Reduced-dose radiotherapy and intensified chemotherapy for iGCT, especially NGGCT, improved the clinical outcome and QOL of long-term survivors, suppressing late complications. Further comprehensive follow-up and analysis are needed.
HGG-02. Epigenetic transcription regulation and 3D genome structure in pediatric high-grade glioma
Authors: Huang Tina , Wang Juan , Hu Ye , Piunti Andrea , Bartom Elizabeth , Shilatifard Ali , Yue Feng , Saratsis Amanda
Published: June 2022

INTRODUCTION: Pediatric high-grade gliomas (pHGGs), including glioblastoma multiforme (GBM) and diffuse intrinsic pontine glioma (DIPG), are highly morbid brain tumors. Up to 80% of DIPGs harbor a somatic missense mutation in genes encoding Histone H3. To investigate whether the H3K27M mutant protein is associated with distinct chromatin structure affecting transcription regulation, we generated the first high-resolution Hi-C and ATAC-Seq maps of pHGG cell lines, and integrated these with tissue and cell genomic data. METHODS: We generated sequencing data from patient-derived cell lines (DIPG n=6, GBM n=3, normal n=2) and frozen tissue specimens (DIPG n=1, normal brainstem n=1). Analyses included cell line RNA-Seq, ChIP-Seq (H3K27ac, H3K27me3, H3K27M) and genome-wide chromatin conformation capture (Hi-C), as well as tissue ATAC-Seq. Publicly available pediatric glioma tissue ChIP-Seq data was integrated with cell data. CRISPR knock-down of target enhancer regions was performed. RESULTS: We identified tumor-specific enhancers and regulatory networks for known oncogenes in DIPG and GBM. In DIPG, FOX, SOX, STAT and SMAD families were among top H3K27Ac enriched motifs. Significant differences in Topologically Associating Domains (TADs) and DNA looping were observed at OLIG2 and MYCN in H3K27M mutant DIPG, relative to wild-type GBM and normal cells. Pharmacologic treatment targeting H3K27Ac (BET and Bromodomain inhibition) altered these 3D structures. Functional analysis of differentially enriched enhancers in DIPG implicated SOX2, SUZ12, and TRIM24 as top activated upstream regulators. Distinct genomic structural variations leading to enhancer hijacking and gene co-amplification were identified at A2M, JAG2, and FLRT1. CONCLUSION: We show genome structural variations enhancer-promoter interactions that impact gene expression in pHGG in the presence and absence of the H3K27M mutation. Our results imply that tridimensional genome alterations may play a critical role in the pHGG epigenetic landscape and thereby contribute to pediatric gliomagenesis. Further studies examining the impact of the alterations are therefore underway.
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

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

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

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 >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

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

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.