bluuebunny/crossref_metadata_2025 huggingface dataset:
ETMR-25. UNRAVELING THE ROLE OF SHH SIGNALING PATHWAY IN RETINOBLASTOMA
Authors: Liu Xiao , Zhang Jiao , Xu Zhenhua , Dlugosz Andrzej , Frank Stephan , Meyer Peter , Suzuki Hiromichi , Nakashima Taakuma , Pei Yanxin
Published: June 2024

BACKGROUND

Retinoblastoma (RB) is a pediatric cancer affecting the retina, often requiring surgical removal of one or both eyes due to the limited effectiveness of current treatments. There is an urgent need for advanced therapeutic strategies capable of effectively eliminating tumors, thereby obviating the need for surgical removal of eyes in affected children. Achieving this goal requires a deeper understanding of the cellular and molecular mechanisms governing RB initiation and progression.

METHODS

Using a transgenic mouse model, we identified the crucial role of the Shh signaling pathway in Rb1 mutation-induced tumorigenesis, highlighting its potential as a novel therapeutic target for RB treatment.

RESULTS

We have observed frequent overexpression of Shh signaling proteins (SHH, GLI1, and GLI2) in human RB, correlating with aggressive clinicopathological features. GLI2 overexpression is necessary for Rb1 deletion-induced RB tumor initiation in mouse retinal progenitor cells (RPCs). These mouse intraocular tumors accurately replicate human RB at both cellular and molecular levels. Additionally, Shh pathway activation extends to normal retinal cells adjacent to human RB tumors, suggesting the involvement of Shh signaling in RB-microenvironment interactions. Importantly, our studies have identified a novel small molecular inhibitor targeting the Shh pathway, effectively inhibiting RB growth in vitro and in vivo by targeting both tumor cells and the tumor microenvironment (TME).

CONCLUSIONS

The proposed research aims to provide unprecedented insights into the role of SHH signaling pathway in RB initiation and progression and the supporting communication network between RB tumors and TME. These outcomes have the potential to treat RB effectively while improving the well-being of young individuals with RB and those at risk of RB.
ETMR-32. SUPRATENTORIAL NEUROEPITHELIAL TUMOR WITH PLAGL1 FUSION: A CASE REPORT
Authors: Rocco Abbey , Beck Mary , McHugh Michele , Lampe Ashley , Meyer Ashley , Ogle Andrea , Cluster Andrew , Brossier Nicole M , Dahiya Sonika , Abdelbaki Mohamed S , Perkins Stephanie , Roland Jarod , Shatara Margaret
Published: June 2024

BACKGROUND

Supratentorial neuroepithelial tumor with PLAGL1 fusion has emerged as a novel subgroup within pediatric brain tumors. Despite its recent identification, critical aspects such as optimal clinical characteristics and management strategies remain elusive. This case report aims to contribute essential insights to the growing body of literature surrounding this enigmatic tumor entity, providing a detailed exploration of its clinical presentation and histopathological features.

METHODS

A retrospective chart review was conducted, and relevant data were analyzed.

RESULTS

An 11-year-old female presented with a two-week history of headaches, vomiting, lethargy, and decreased oral intake. Neuroimaging revealed a left frontal lesion with conspicuous mass effect and midline shift, prompting urgent craniotomy due to sudden onset altered mental status. Histopathological analysis revealed a hypercellular glial neoplasm characterized by perivascular pseudorosettes, scattered microcalcifications, microcysts, and areas of necrosis. Immunohistochemical staining revealed GFAP positivity in a substantial subset of tumor cells, rare dot-like positivity for EMA, and diffuse membranous and focal dot-like positivity for D240. Olig2 was mostly negative, indicating the absence of Oligodendrocyte lineage differentiation. The tumor exhibited an elevated Ki-67 proliferation index (approximately 20-30%). Fluorescence in situ hybridization (FISH) studies were negative for RELA, YAP1, and C19MC rearrangements. Targeted next-generation sequencing unveiled an EWSR1-PLAG1 fusion and methylation profiling classified the tumor as “Neuroepithelial tumors, PLAG1-fused” with high confidence. Given the morphological resemblance to anaplastic ependymoma, the therapeutic recommendation included focal irradiation (54 Gy) with proton therapy. The patient, now 12 months post-therapy, is showing favorable clinical outcomes.

CONCLUSION

This case report underscores the clinical and histopathological intricacies of supratentorial neuroepithelial tumors with PLAGL1 fusion. The identification of EWSR1-PLAG1 fusion and associated molecular alterations informs diagnostic considerations and treatment strategies for this novel entity, emphasizing the importance of continued research to enhance our understanding of its clinical behavior and optimal management approaches.
EPEN-01. DISTINCT RELAPSE PATTERN ACROSS MOLECULAR EPENDYMOMA TYPES
Authors: Obrecht-Sturm Denise , Schoof Melanie , Eckhardt Alicia , Mynarek Martin , Gilbert Mark R , Adalpe Kenneth , Armstrong Terri S , Ramaswamy Vijay , Bockmayr Michael L , von Hoff Katja , Fleischhack Gudrun , Adolph Jonas E , Tippelt Stephan , Pfister Stefan M , Pajtler Kristian , Sturm Dominik , Drexler Richard , Ricklefs Franz L , Stephien Natalia , Gojo Johannes , Pietsch Torsten , Warmuth-Metz Monika , Kortmann Rolf-Dieter , Timmermann Beate , Haberler Christine , Rutkowski Stefan , Schüller Ulrich
Published: June 2024

BACKGROUND

Ependymoma (EPN) is not a uniform disease but represents different tumor types with biological and clinical heterogeneity. Some types have an excellent prognosis; others display frequent relapse. However, the pattern of when and where different types of EPN relapse is largely unknown.

METHODS

We assembled 552 intracranial EPN from pediatric (n=445) and adult (n=107) patients from European and Northern American cohorts and correlated DNA methylation patterns and copy-number alterations with clinical information. Median age at diagnosis was 13.4±18.8 (0.1 – 80) years.

RESULTS

In 271/552 (49.1%) of included EPN relapse occurred. First relapses occurred in the initial tumor bed in 70.9%, 22.4% were metastatic only, and 6.7% were combined local and metastatic. First relapses of PF-EPN-B (PF: posterior-fossa) and PF-EPN-SE (SE: subependymoma) occurred later than of PF-EPN-A, ST-EPN-YAP (ST: supratentorial), or ST-EPN-ZFTA (median time to relapse: 4.3 and 6.0 years vs. 1.9/1.0/2.5 years; p<0.01). Metastatic or combined recurrences in PF-EPN-B and -A occurred more often in the spinal cord than in ST-EPN-ZFTA (75.0% and 40.0% vs. 12.5%; p<0.01). In the latter, relapse occurred more frequently when harboring an alternative fusion or CDNK2A loss (p<0.01, respectively). No distant relapses were observed in ST-EPN-YAP (n=9) or PF-EPN-SE (n=60). Post-relapse survival (PRS) was poor for PF-EPN-A and ST-EPN-ZFTA (5-year PRS: 44.5±4.4/ 47.8±9.1%), whereas PF-EPN-B and PF-EPN-SE displayed a 5-year PRS of 89.5±7.1/ 90.0±9.5% (p=0.03). However, 10-year PRS for PF-EPN-B dropped to 45.8±17.3%.

CONCLUSIONS

Relapse patterns of specific EPN types are different. Duration of surveillance and diagnostics should be planned incorporating entity-specific relapse information. Follow-up should be performed longer than 5 years after diagnosis. Spinal MRI should be considered as standard procedure during surveillance, particularly for PF-EPN-A, PF-EPN-B and ST-EPN-ZFTA.
EPEN-02. CAR T-CELLS TARGETED TO B7-H3 OR HER2 FUNCTION INDEPENDENTLY OF ANTIGEN DENSITY IN XENOGRAFT MODELS OF EPENDYMOMA
Authors: Mehta Sanya , Ibanez Jorge , Houke Haley , Emanus Erik , Ippagunta Siri , Mack Stephen C , Krenciute Giedre
Published: June 2024

BACKGROUND

Targeted treatment options are desperately needed for ependymomas (EPN). Chimeric antigen receptor (CAR) T-cells have immense potential to positively transform treatment outcomes; however, little is known regarding antitumor efficacy of CAR T-cells against EPNs. Specifically, antigen density has emerged as a major influencer of CAR T-cell potency. However, the specific high and low antigen density thresholds governing CAR T-cell efficacy for EPN are unknown. We hypothesize that antigen density heterogeneity governs CAR T-cell potency against EPN.

METHODS

Using quantitative flow cytometry, we determined antigen density of B7-H3 and HER2 (the two CAR targets currently in pediatric EPN clinical trials) on EPN patient derived cell lines (1425, ST1, CPITT, ST2, EPI, L46SJ). We generated second generation B7-H3 and HER2-CAR T-cells with CD28z signaling domain and compared long-term cytolytic activity, expansion, and cytokine production against EPNs.

RESULTS

We found that all EPN cell lines express remarkably high yet variable density of B7-H3 (6.3e4 – 3.4e5 molecules/ cell). In contrast, surface density of HER2 was consistently and significantly lower (860 – 2.5e4 molecules/ cell). In repeated-stimulation assays, B7-H3-CAR T-cells killed 7-10 times and expanded up to 325,360-fold when cultured against EPN. However, we observed no significant difference in total expansion or correlation with antigen density against EPNs. Surprisingly, expansion of HER2-CAR T-cells against EPNs was drastically higher (up to over 100-billion-fold) and greatly exceeded that of B7-H3-CAR-T cells against the same EPN cells despite much lower antigen density.

CONCLUSIONS

Our studies reveal significant antigen density heterogeneity of B7-H3 and HER2 in EPN, which may lead to target-specific impacts on CAR T-cell persistence. Indeed, results suggest that lower antigen density of HER2 may be superior for sustained CAR T-cell activity. Future work will validate whether HER-CAR T-cells have superior antitumor efficacy in vivo to further delineate role of antigen density thresholds in CAR T-cell potency.
EPEN-03. THE MANAGEMENT OF PEDIATRIC AND ADOLESCENT SPINAL EPENDYMOMA; A 20-YEAR NATIONAL EVALUATION INVOLVING UNITED KINGDOM PEDIATRIC ONCOLOGY PRIMARY TREATMENT CENTERS ON BEHALF OF THE UK CHILDREN’S CANCER AND LEUKAEMIA GROUP (CCLG)
Authors: Deghedy Marwa , English Martin , Curry Helen , Nicholson James , O’Hare Patricia , McCarthy Anthony , Uzunova Lena , Curry Sarah , Wilson Shaun , Jorgensen Mette , Thompson Dominic , Cox Rachel , Ronghe Milind , Brougham Mark , McAndrew Rachel , Lee Victoria , Bailey Simon , Thorbinson Colin , Goodden John , Picton Susan , Dias Sandra , Saeed Fozia , Srivatsa Kavitha , Ritzmann Timothy , Grundy Richard , Kilday John-Paul
Published: June 2024

INTRODUCTION

Pediatric spinal ependymomas account for approximately 1% of childhood CNS tumors. Most are myxopapillary ependymomas (MPEs). For symptomatic cases, maximal safe surgical resection is the accepted therapeutic standard. However, a role for adjuvant therapy is unclear, underpinned by low incidence rates, inadequate trial data and recent WHO upgrading of the MPE variant. This retrospective national service evaluation aimed to provide safety and outcome data, from which future management guidance could be developed.

METHOD

Children, teenagers and young adults diagnosed with a spinal ependymoma of any WHO grade since 2000 across 17 UK CCLG centres were evaluated. Patient demographics, therapies, adverse events, and outcomes were captured.

RESULTS

102 patients were evaluated. Ten children had NF2 (median age 11 (7.6 – 14) years) with nine located in the cervicomedullary region. All ten patients were alive following surveillance (n=3) or surgical intervention (n=7) with an estimated median PFS of 5.4 (1.7 – 9.1) years. For the remaining 92 patients (median age 12 (0.7 – 19) years), 63% of tumors were lumbosacral, 73% demonstrated MPE morphology and 16% were metastatic. The median symptom interval was 4 (0 - 36) months. Progression or relapse was reported in 30/92 (33%), with a 5-year PFS of 62(+ 6)%, yet only 4 disease-related deaths occurred (mean follow-up 6.8 years; no MPEs). Across this non-NF2 cohort, gross/near total resection and upfront adjuvant radiotherapy independently reduced disease progression risk (p < 0.05). However, improved local control from early irradiation was not statistically proven when localized disease or MPEs were exclusively scrutinized. No radiotherapy-related high-grade toxicity was reported.

DISCUSSION

Pediatric spinal ependymomas are rare tumors demonstrating excellent survival, particularly MPEs. Maximal safe surgery and early adjuvant radiotherapy can improve local control rates, but European collaboration will be required to evaluate efficacy for certain tumor and clinical subgroups. Conclusions could support future national management guidelines.
EPEN-14. MOLECULAR MARKERS AND PREDICTORS OF OUTCOME FOR PAEDIATRIC INTRACRANIAL EPENDYMOMA IN THE PROSPECTIVE, MULTICENTRE E-HIT2000 TRIAL AND SUBSEQUENT HIT-REGISTRIES: A POOLED ANALYSIS OF 244 PATIENTS
Authors: Ghasemi David R , von Hoff Katja , Obrecht-Sturm Denise , Wenning Janna , Mynarek Martin , Gerber Nicolas U , Benesch Martin , Juhnke Björn O , Bison Brigitte , Warmuth-Metz Monika , Timmermann Beate , Faldum Andreas , Fleischhack Gudrun , Grotzer Michael , Driever Pablo Hernáiz , Beilken Andreas , Ebinger Martin , Graf Norbert , Frühwald Michael , Schmid Irene , Koch Arend , Bergmann Markus , Hagel Christian , Coras Roland , Blümcke Ingmar , Reifenberger Guido , Felsberg Jörg , Keyvani Kathy , Harter Patrick N , Prinz Marco , Staszewski Ori , Acker Till , Brück Wolfgang , Hartmann Christian , von Deimling Andreas , Sommer Clemens , Hasselblatt Martin , Riemenschneider Markus J , Monoranu Camelia-Maria , Rushing Elisabeth , Kool Marcel , Pfister Stefan M , Schüller Ulrich , Pietsch Torsten , Kortmann Rolf D , Kwiecien Robert , Witt Hendrik , Pajtler Kristian W , Rutkowski Stefan
Published: June 2024

BACKGROUND

Throughout the past decade, molecular tools have revolutionised ependymoma classification, yet their application has been limited in clinical trial cohorts.

METHODS

We present the molecular analysis of paediatric ependymoma patients from the E-HIT2000 trial (n = 165), or subsequent HIT2000-interim and I-HIT-MED registries (n = 79) based on DNA-methylation profiling with multi-level classification using the Heidelberg Brain Tumor Classifier v12.5 and the analysis of chromosome 1q, 6q, and CDKN2A copy number status. Prior to further analysis, cases without ependymoma group prediction were excluded (n = 16/244).

RESULTS

5-year PFS and OS rates varied by group: EPN-PFA (n=146/228) 45±4% and 76±4%; EPN-PFB (n=19/228) 90±7% and 100%; EPN-ZFTA (n=59/228) 63±7% and 87±5%; and EPN-YAP1 (n=4/228) 50±25% and 100%. EPN-PFA was subclassified into nine subtypes. Poor median PFS was observed for PFA1c (n=22, 5-yr-PFS 32±10%/5-yr-OS 77±9%), PFA1d (n=13, 35±14%/72±14%), PFA1e (n=15, 47±13%/59±13%), and PFA2a (n=16, 27±12%/50±14%). Presence of 1q gain was associated with inferior survival (n = 39/146, 29±8%/65±8%). 6q loss impacted PFS, but not OS (n=8, 25±14%/100%). Among 59 EPN-ZFTA cases, 46 clustered with EPN ZFTA-RELA fused, and 12 clustered within recently described subgroups of EPN-ZFTA (EPN-ZFTA alt., Cluster 1: 1/12, Cluster 2: 11/12). Strikingly, 6/11 EPN ZFTA-alt. (Cluster 2) cases showed infratentorial (4/6) or supratentorial midline location (2/6). Homozygous deletion of CDKN2A (CDKN2A-/-; n=8) was only observed in EPN ZFTA-RELA. Presence of EPN ZFTA-alt. (cluster 2) (5-yr-PFS: 36±15%; p<0.001), and CDKN2A-/- (19±16%; p<0.0001) was associated with inferior PFS compared to EPN ZFTA-RELA CDKN2A-wt (81±6%). OS was only impacted for patients with EPN ZFTA-RELA CDKN2A-/- (5-yr-OS: 38±20%, p>0.0001).

CONCLUSIONS

We present strong evidence supporting the inclusion of molecular criteria into the next generation of clinical trials for children with ependymoma.
EPEN-15. TRANSCRIPTOMIC AND METABOLOMIC INTEGRATION REVEAL INTRA-TUMOUR HETEROGENEITY AND IDENTIFY DISULFIRAM AND COPPER AS A SYNERGISTIC THERAPY IN PAEDIATRIC EPENDYMOMA
Authors: Pandele Alina , Whitby Alison , Lankford Sophie J , Macarthur Donald , Kamaly-Asl Ian , Barrett David , Grundy Richard , Kim Dong-Hyun , Rahman Ruman
Published: June 2024

BACKGROUND

Ependymoma (EPN) is the second most malignant paediatric brain tumour. The PF-A subgroup, associated with a hypoxic microenvironment, has a dismal survival rate of 50% with clinical trials failing to demonstrate a significant survival advantage from chemotherapy to date. As the lack of genomic alterations makes it difficult to uncover novel therapeutic targets, we present a multi-omic integration investigating whether spatially-distinct tumour microenvironments represent targetable metabolic niches in PF-A EPN.

METHODS

Surgical sampling of spatially-distinct regions was performed on eight PF-A EPN patients. Metabolites and RNA were simultaneously extracted from the same cellular population and analysed using liquid chromatography-mass spectrometry (LC-MS) and RNAseq. Multi-omic integration was performed using Metscape3 and functional assays evaluating proliferation, invasion and siRNA-mediated knockdown were performed in 2D and 3D models of intra-tumour region patient-derived cell lines. Selected single and drug combination therapy was performed in normoxia and hypoxia, and synergy assessed using the Chou-Talalay method.

RESULTS

Multi-omic integration revealed 124 dysregulated metabolic pathways, encompassing 156 genes and 49 metabolites with the largest number of interactions occurring in the gluconeogenesis pathway. Each anatomical region also presented at least one unique gene-metabolite interaction demonstrating heterogeneity within and across PF-A EPN tumours. Four selected drug targets (Disulfiram, Vandetanib, Mildronate and FBP1 inhibitor) based on metabolically relevant genes (ALDH3A1, FMO3, BBOX1, FBP1) showed impairment of metabolic viability in vitro, with limited chemosensitivity observed in control human cerebellar astrocytes. The addition of Cu2+ significantly sensitised cells to Disulfiram, particularly under hypoxic conditions. This synergistic combination significantly impaired invasion in both normoxia and hypoxia.

CONCLUSION

This is the first instance where multi-omic data integration and intra-tumour heterogeneity has been investigated for paediatric EPN revealing novel therapeutic targets in the context of gene-metabolite correlations. Drug tolerability will be further assessed in vivo using the previously characterised PF-A EPN orthotopic mouse xenograft MAF-928.
EPEN-16. BULK AND SINGLE-CELL SPATIAL CHARACTERIZATION OF THE TUMOR IMMUNE MICROENVIRONMENT OF POSTERIOR FOSSA GROUP A EPENDYMOMAS
Authors: Lammers Julie A S , Kranendonk Mariëtte E G , Calkoen Friso G , van den Broek Thijs J M , Federico Aniello , Kool Marcel , Hoving Eelco W , Wesseling Pieter , Kester Lennart A , van der Lugt Jasper
Published: June 2024

BACKGROUND

Despite advancements in molecular classification of ependymomas, the tumor immune microenvironment of posterior fossa group A (PFA) ependymomas and the spatial interplay between tumor and immune cells have not been elucidated. Here, we aim to comprehensively characterize the tumor immune microenvironment of pediatric PFA ependymomas, which could ultimately uncover leads for immunotherapy for these children.

METHODS

We collected bulk RNA-sequencing data of 28 PFA ependymoma samples and defined two subgroups based on the expression of immune-related genes (n = 716). Furthermore, we analyzed single-cell RNA-sequencing data of PFA ependymomas to dissect myeloid and lymphocyte heterogeneity, which we subsequently used to deconvolute bulk data. Lastly, we performed both high-dimensional cyclical immunofluorescence of 20 protein markers on a tissue microarray containing 60 cores from 20 tumor samples and immunohistochemistry on whole tissue slides.

RESULTS

Unsupervised hierarchical clustering of bulk RNA expression of immune-related genes revealed the presence of an immune-enriched subgroup. Furthermore, analysis of single-cell RNA-sequencing data identified multiple distinct myeloid cell subpopulations, with gene expression signatures reflective of inflammation, angiogenesis/hypoxia response and proliferation. Deconvolution of the bulk RNA-sequencing data using the newly annotated single-cell data as a reference showed enrichment of both myeloid cells and lymphocytes in the immune-enriched subgroup. Lastly, spatial immune profiling enabled detailed mapping of the organization of the tumor immune microenvironment and unveiled a heterogeneous presence of myeloid cells, with enrichment of infiltrating myeloid and T-cells in peri-necrotic areas compared to areas with high tumor cell density.

CONCLUSIONS

Our multi-faceted approach has shed unprecedented light on the cellular and spatial heterogeneity within the PFA ependymoma immune microenvironment. Further studies are warranted to unravel the functional differences between the two subgroups and the potential impact on response to future immunotherapeutic approaches/interventions.
EPEN-19. IMPACT OF MOLECULAR SUBTYPING ON PROGNOSIS IN CHILDREN AND ADOLESCENTS WITH SPINAL EPENDYMOMA
Authors: Engertsberger Lara , Benesch Martin , Mynarek Martin , Tonn Svenja , Obrecht-Sturm Denise , Perwein Thomas , Stickan-Verfürth Martina , Funk Angela , Timmermann Beate , Claviez Alexander , Kortmann Rolf-Dieter , Riemenschneider Markus J , Pietsch Torsten , Bison Brigitte , Warmuth-Metz Monika , Pajtler Kristian W , Rutkowski Stefan , Schüller Ulrich
Published: June 2024

PURPOSE

Ependymomas of the spinal cord are rare among children and adolescents, and the individual risk of disease progression is difficult to predict. Recent advances in subtyping the main molecular groups, myxopapillary ependymoma (MPE) and spinal ependymoma (SP-EPN), have successfully identified distinct risk groups among adult patients. This study aims at evaluating the prognostic impact of MPE subtypes A and B in a pediatric cohort.

METHODS

Eighty-three patients with spinal ependymoma ≤22 years registered in the HIT-MED database between 1992 and 2022 were included. Forty-seven tumors were analyzed regarding global DNA methylation. In six cases, antibodies against HOXB13 and MYCN were used as surrogate markers for the methylation group. Twenty-eight MPE were further classified into subtypes by t-distributed stochastic neighbor embedding (t-SNE) analysis.

RESULTS

MPE (n=32, 63%) was the most common molecular type followed by SP-EPN (n=17, 33%) and MYCN-amplified ependymoma (n=2, 4%). One case remained molecularly unclear, and one was excluded due to reclassification as anaplastic pilocytic astrocytoma. MPE subtyping identified 18 MPE-A and 9 MPE-B (inconclusive: n=1). 5-year progression-free survival (5y-PFS) did not significantly differ between MPE and SP-EPN (65% vs. 78%, p=0.64). MYCN-amplification was associated with early relapses and with death in one patient. Patients with MPE-B may have a tendency towards superior 5y-PFS compared to MPE-A (86% vs. 56%, p=0.15), irrespective of the use of adjuvant treatment. MPE-A was more frequently disseminated at time of diagnosis (n=6/18) than MPE-B (n=1/8, not evaluable: n=1; p=0.28).

CONCLUSION

Molecular subtyping of spinal ependymoma in children does not allow to separate patients into distinct risk groups, yet. However, the potentially favorable PFS among patients with MPE-B prompts the consideration of treatment de-intensification for this group. Larger cohorts and further insights into the molecular heterogeneity of these tumors are needed to complete the basis for future clinical decision-making.
EPEN-20. LEVERAGING ABERRANT EXTRACELLULAR VESICLE SIGNALING FOR TARGETED DRUG REPURPOSING IN PEDIATRIC EPENDYMOMA
Authors: Maass Kendra K , Rettenmeier Johanna , Sundheimer Julia K , Roosen Mieke M , Volz Stefanie , Wedig Tatjana , Ertel Paula , Gansert Cornelia , Richter Karsten , Nessling Michelle , Peterziel Heike , Friedenauer Aileen , Herter Sonja , Oehme Ina , Scheuermann Sophia , Seitz Christian , Senfter Daniel , Benzel Julia , Mueller Torsten , Okonechnikov Konstantin , Genard Geraldine , Krijgsveld Jeroen , Pfister Stefan M , Pajtler Kristian W
Published: June 2024

Increasing evidence highlights the diverse functions of extracellular vesicles (EVs) as intercellular messengers in all facets of cancer progression, pointing towards a potential new avenue in cancer treatment. Limited understanding of tumor-specific deregulations and lack of suitable drug compounds have hampered clinical translation of targeted interference with EV signaling. The most aggressive types of intracranial ependymoma (EPN) in children and adults are resistant to chemotherapy. Despite enormous diagnostic advancements in classification and stratification, EPN lack recurrent effective molecular targets precluding access of affected patients to precision-based oncology therapeutics. Here, we characterized the proteome of ninety-five EPN and five matching healthy control brain tissue samples. Employing a mulit-omic data integration approach, we identified EVs as an excessively augmented pathway on the functional level. Isolation and molecular characterization of EPN EVs combined with single cell sequencing analysis, and ultra-high content imaging unraveled perivascular mesenchymal cell populations as predominant EV originators. Targeting EV pathways through chemical inhibition of sphingomyelinases (SMPD1, SMPD2, SMPD3) including re-purposed FDA approved compounds revealed growth inhibition, reduced invasion capacity in vitro and significant survival probability in vivo. Transcriptomic analysis and scanning electron microscopy delineated transition of mesenchymal-to neuroepithelial subpopulations in cells and patient-derived xenograft (PDX) models of EPN upon reduction of EV release. This study showcases the inhibition of EV signaling as a promising therapeutic strategy against mesenchymal tumor persister cells, which are the suspected origins of repeated EPN relapses. Our study provides a framework to leverage cell state-specific vulnerabilities and drug repurposing to attack the most aggressive cell populations in cancers with unfavorable prognosis.
EPEN-22. ZFTA FUSION ONCOPROTEINS DRIVE ONCOGENESIS THROUGH ASSEMBLY OF BIOMOLECULAR CONDENSATES
Authors: Varadharajan Srinidhi , Arabzade Amir , Shirnekhi Hazheen K , Ippagunta Siri , Laboe Nic , Gee David , Emanus Erik , Kardian Alisha , Phillips Aaron H , Tripathi Swarnendu , Shirinifard Abbas , Petersen Becky , King Sharon , Stabley Daniel , Pitre Aaron , Campbell George , Park Cheon-Gil , Durbin Adam D , Qi Jun , Bertrand Kelsey , Taylor Michael D , Northcott Paul A , Deneen Benjamin , Ansari Aseem Z , Kriwacki Richard W , Mack Stephen C
Published: June 2024

BACKGROUND

Ependymomas continue to be an aggressive brain tumor entity without targeted therapies. The highly recurrent fusion oncoprotein (FO), ZFTA-RELA, is known to be associated with about 70% of supratentorial ependymomas. While recent studies have highlighted that the fusion protein is involved in aberrant DNA binding and subsequent oncogenic gene expression, the precise mechanisms underlying the transcriptional dysregulation remain elusive.

METHODS

Using super-resolution and lattice-sheet microscopy, we demonstrate that ZFTA-RELA forms dynamic liquid-like nuclear condensates. ZFTA-RELA condensates recruit co-factors like Med1, and Brd4 and are associated with the transcription of ependymoma oncogenes (Notch1 and Ccnd1). We leveraged machine learning models trained on FOs in other cancers to identify critical intrinsically disordered domains (IDRs) within ZFTA-RELA. A series of mutagenesis experiments were conducted to determine IDRs important for condensate formation, transcription, and tumor initiation. We also performed NMR spectroscopy to unravel the protein structure of ZFTA-RELA zinc finger binding domains.

RESULTS

We demonstrate that transcriptional condensate formation of ZFTA-RELA is an important cellular phenotype that is tightly linked with oncogenic transcription and tumor initiation. Further, we identify key residues within the zinc finger domain of ZFTA that are required for DNA binding of oncogenic target genes and condensate formation. Deletion of the key IDRs within ZFTA-RELA disrupts condensates and abolishes transcriptional activation and tumorigenesis. We also show that condensate formation is an underlying feature found across all other ZFTA-fusion oncoproteins, providing a model to understand how ZFTA FOs drive cancer.

CONCLUSION

Our studies provide mechanistic insights into the biophysical and structural basis of ZFTA fusion oncoproteins. These findings provide a framework to develop druggable strategies through targeting ZFTA FO zinc finger domains or disruption of oncogenic condensates.
EPEN-26. DRUG SCREENING IN PATIENT-DERIVED MODELS OF POSTERIOR FOSSA A EPENDYMOMA REVEALS NOVEL PHARMACOLOGICAL VULNERABILITIES
Authors: Larson Jon D , Finlay Darren , Murad Rabi , Lo Yan Yuen , Zhao Ming , Manuvel Antony Michealraj Kulandai , Kumar Sachin A , Pass Ian , Handley Charles , Wechsler-Reya Robert J , Taylor Michael D , Vuori Kristiina , Chavez Lukas , Jackson Michael
Published: June 2024

Ependymoma (EPN) is the third most common malignant intracranial pediatric brain tumor. The most common and aggressive EPN subgroup, posterior fossa ependymoma group A (PFA-EPN), occurs predominantly in younger children and has a 5-year progression free survival of only 33%. Despite progress in the molecular characterization and subtyping of EPN, the standard treatment remains surgery with adjuvant radiation therapy. There is currently no approved role for chemotherapy in PFA-EPN. As such, identifying novel therapies for PFA-EPN is an important unmet medical need. To define therapeutic sensitivities for PFA-EPN, we performed a drug screen on three patient-derived PFA-EPN cell lines. We found that PFA-EPN cell lines were sensitive to several clinically relevant drugs, most notably those targeting epigenetic regulators. This is of a particular interest as a common molecular feature of PFA-EPN is the global reduction of the repressive post-translational histone modification H3K27me3 due to transcriptional EZHIP overexpression or H3 K27M mutations. To further characterize our PFA-EPN cell lines, we performed optical genome mapping analysis, revealing previously undescribed structural variants affecting genes encoding proteins responsible for signaling and transcription. One PFA-EPN sample that showed profound sensitivity to EGFR inhibitors, also had a duplication of a genomic region containing the EGFR ligand encoding genes, AREG, BTC, EREG, and EPGN. We are currently working to validate these results in larger cohorts of PFA-EPN models. Collectively, these findings provide new clues on drugs, signaling and putative therapeutic targets in these rare yet aggressive tumors.
EPEN-29. IS THE OUTCOME OF SUPRATENTORIAL EPENDYMOMA WITH ZFTA FUSION REALLY POOR?
Authors: Smith Amy A , Lensing Shelly , Onar-Thomas Arzu , Leary Sarah , Fouladi Maryam , Foreman Nicholas K , Ellison David W
Published: June 2024

BACKGROUND

Survival of children with intracranial ependymoma is known to depend, in part, on the molecular group of the tumor. Previous studies have linked both PFA and ZFTA molecular group ependymomas to poor outcomes. As part of an unplanned analysis from ACNS0831, we explored outcomes for ZFTA supratentorial (ST) and PFA ependymomas.

METHODS

Patients were stratified by location, grade and extent of resection. Grade 2, ST tumors with no evidence of disease were observed only, N=37. All other patients were randomized to RT versus RT + maintenance chemotherapy or non-randomly assigned to RT + M if residual disease. A planned “as treated” analysis was performed by actual treatment received for randomized patients, excluding those who did not receive RT. Molecular groups were compared using two-sided log-rank tests stratified by study arms for all and randomized patients. Molecular characterization was achieved in 161/166 (97%) ST and 282/283(99.6%) PF. Among ST, 94% were classified ZFTA and 6% YAP1. Homozygous CDKN2A deletion was detected in 16 tumors, all ZFTA and WHO grade 3. Among posterior fossa ependymomas, 88% were classified as PFA and 12% as PFB.

RESULTS

There was no statistical difference in outcome according to treatment. Across all study arms, 5-year EFS was 69.6%+4.3 for ZFTA vs. 52.9%+3.4 for PFA (p=0.028). For the randomized cohort, 5-year EFS was 72.1+4.8 for ZFTA vs. 60.1+3.9 for PFA (p=0.076). For the randomized cohort with initial GTR/NTR, 5-year EFS was 74.1+5.1 for ZFTA patients vs. 61.0+4.2 for PFA patients (p=0.045). The 5-year EFS was 66.7+12.2 for ZFTA patients with CDKN2A deletion vs. 69.3+4.7 for ZFTA patients without CDKN2A deletion (p=0.232)

CONCLUSION

Children with ST ZFTA ependymomas have a significantly better outcome than those with PFA tumors. Homozygous deletion of CDKN2A was present in 12% of ST ependymomas but was not an indicator of poor outcome.
EPEN-30. PROTON THERAPY FOR PEDIATRIC INTRACRANIAL EPENDYMOMA: A SYSTEMATIC REVIEW, META-ANALYSIS AND META-REGRESSION
Authors:   Amanda Cyntia Lima Fonseca Rodrigues
Published: June 2024

BACKGROUND

Pediatric intracranial ependymoma (IE) represents a challenging subset of tumors necessitating tailored therapeutic strategies. Conventional treatments, including surgery and conventional radiation therapy, have shown limitations in achieving optimal outcomes, particularly in preserving neurocognitive function and mitigating long-term sequelae. Proton therapy (PT) has emerged with its ability to offer precise tumor targeting with reduced irradiation of healthy surrounding tissues.

METHODS

A systematic search was conducted using the electronic databases PubMed, CENTRAL, and EMBASE from inception through February 2024 following the PRISMA statement. Statistical analysis was conducted using R (R Foundation for Statistical Computing; Vienna, Austria) with the packages ‘meta’ and ‘metafor’. The random effects model of proportions was estimated using the generalized linear mixed-effects model (GLMM) method.

RESULTS

A total of 7 studies were included comprising 943 patients, with a mean age of 4 years, 543 boys (57.58%) and a mean dose of 56.94 Gy. The local control (LC) rate at 3 years was 83% (95% CI = 0.80 to 0.86, p=0.65) and a 5-year rate was 81% (95% CI = 0.72 to 0.89, p=0.35). Progression-free survival (PFS) was 75% at 3 years (95% CI = 0.68 to 0.82, p=0.17) and 71% at 5 years (95% CI = 0.56 to 0.87, p=0.07). Overall survival (OS) rates were notably high, with 93% at 3 years (95% CI = 0.89 to 0.97, p=0.11) and 85% at 5 years (95% CI = 0.83 to 0.87, p=0.96). Meta-regression analysis revealed that total dose significantly influenced 3-year OS (p=0.04), indicating a dose-dependent effect on survival rates.

CONCLUSIONS

This meta-analysis supports the effectiveness of PT through the outcomes LC, PFS and OS in pediatric IE. The significant correlation between total dose and 3-year OS underscores the importance of dose optimization in treatment planning. These findings highlight the importance of PT in pediatric neuro-oncology management, offering evidence-based guidance for enhancing therapeutic strategies and patient outcomes.
EPID-01. ESTIMATING THE BURDEN DUE TO BRAIN AND OTHER CNS TUMORS IN ADOLESCENTS IN THE UNITED STATES
Authors: Price Mackenzie , Neff Corey , Kruchko Carol , Waite Kristin A , Cioffi Gino , Cordeiro Brittany , Penas-Prado Marta , Gilbert Mark R , Armstrong Terri S , Barnholtz-Sloan Jill S , Ostrom Quinn T
Published: June 2024

BACKGROUND

Brain and other central nervous system (CNS) tumors in adolescents have unique biological and behavioral distinctions from both children and adults. As a result, they pose challenges to treatment and reporting. Here, we describe the epidemiology of brain and other CNS tumors in adolescents (ages 15-19 years) in the United States, including mortality, survival, and prevalence.

METHODS

The Central Brain Tumor Registry of the United States (CBTRUS) data (containing data from the CDC’s National Program of Cancer Registries (NPCR) and NCI’s Surveillance, Epidemiology and End Results (SEER) data) were used to calculate average annual age-specific incidence rates (AASIR) per 100,000 population overall and by sex and race/ethnicity. Average annual age-specific mortality rates (AASMR) per 100,000 population for deaths resulting from all primary malignant brain and other CNS tumors were calculated using mortality data from NCHS. NPCR survival data were used to calculate relative survival (RS). Estimated prevalence counts as of December 31, 2024 were estimated using incidence from CBTRUS and SEER, and survival from SEER.

RESULTS

AASIR for all brain and other CNS tumors among adolescents was 7.51/100,000. Tumors of the sellar region had the highest incidence (AASIR=2.74/100,000). Overall, incidence was higher for females and non-Hispanic White persons. Overall AASMR was 0.56/100,000. Total five-year RS was 92.0%. Tumors of the pituitary had the highest RS (five-years=99.9%) and glioblastoma had the lowest (five-years=16.4%). As expected, prevalence was highest for tumors of the sellar region (3,720 cases).

CONCLUSION

Incidence, prevalence, and survival patterns for brain and other CNS tumors vary between adolescents, adults, and children. An accurate statistical assessment of these tumors in adolescents is required to understand risk and impact on this unique population, and to serve as a reference for afflicted individuals, for researchers investigating new therapies, and for the clinicians who treat them.
EPID-04. CAUSES AND LONG-TERM COURSE OF OTOTOXICITY IN PEDIATRIC MEDULLOBLASTOMA AND EPENDYMOMA PATIENTS – CUMULATIVE PLATINUM AND COCHLEAR IRRADIATION DOSE MATTER
Authors: Öz Elif , Hardt Annika , Kortmann Rolf-Dieter , Schwarz Rudolf , Timmermann Beate , Bison Brigitte , Warmuth-Metz Monika , von Hoff Katja , von Bueren André O , Gerber Nicolas U , Fleischhack Gudrun , Pietsch Torsten , Pfister Stefan M , Sturm Dominik , Mynarek Martin , Rutkowski Stefan , Obrecht-Sturm Denise
Published: June 2024

BACKGROUND

Ototoxicity is a well-known side effect of treatment with platinum-containing chemotherapy and radiotherapy (RT). Nevertheless, precise dose-effect relationships are still lacking.

METHODS

Patients from the HIT2000 trial receiving first-line treatment for medulloblastoma (MB) or ependymoma (EPN) who were alive at last follow-up and had at least one audiogram prior to and after administration of chemotherapy with cisplatinum and radiotherapy were included into this study. Treatment details (incl. cochlear irradiation dose [CID]) and audiological outcome were analyzed. The ototoxicity was graded using the HIT scoring.

RESULTS

Courses of 101 patients were analyzed. Median audiology follow-up was 6 years [range: 1.0–18.1 years]. Ototoxicity grade ≥1 was documented for n=66 patients (65.4%). For n=27 this resulted in treatment modification. Univariable analyses revealed different proportions of ototoxicity (grade ≥1) regarding histology (CMB: 50/65, LCAMB: 3/3, DMB/MBEN: 8/12, EPN: 5/21; p<0.001), tumor location (supratentorial: 3/9, infratentorial: 63/92; p<0.001), metastatic status at diagnosis (M0: 46/77, M+: 20/24; p=0.003), radiation field (CSI: 59/75, local RT: 6/21, no RT: 1/5; p<0.001), CID (continuous variable, p=0.001) and cumulative cisplatinum dose (continuous variable, p<0.001). Certainly, disease specific parameters (histology/staging) were related to treatment intensity (cisplatinum/irradiation dose). Multivariable analyses confirmed the impact of cumulative cisplatinum dose (p=0.01) and CID (p=0.04). ROC-analyses allowed the definition of cut-offs for high risk of ototoxicity grade ≥1 (cisplatinum: 70mg/m2 BSA, CID: 37.5 Gy) and ototoxicity risk estimation, when applying doses above the respective cut-offs (cisplatinum dose increase by 1mg/m2 BSA results in 4% higher risk for ototoxicity grade ≥1; CID dose increase by 1 Gy results in 4.6% higher risk for ototoxicity grade ≥1).

CONCLUSIONS

Ototoxicity affects a majority of children receiving adjuvant treatment for MB and EPN. To avoid disabilities and negative effect on quality of live, dosage of cisplatinum and radiotherapy should be scrutinized and reduced whenever possible.
EPID-09. CONGENITAL CENTRAL NERVOUS SYSTEM NEOPLASMS: A RETROSPECTIVE REVIEW FROM THEMARGARET HACKETT FAMILY PROGRAM CONSORTIUM
Authors: Lopes Carolina , Mosher Amanda M , Papadakis Joanna E , Keusch Dylan , Largen Kelsey , Weber Daniel , Huang Jesse , Yamini Bakhtiar , Bauer David , Danielpour Moise , Sayama Christina , Baird Lissa
Published: June 2024

INTRODUCTION

Congenital intracranial neoplasms are a heterogeneous group of lesions that account for <2% of pediatric CNS tumors. Current understanding of histopathologic and survival outcomes in this population is limited.

METHODS

Pediatric patients (<3-years) with congenital neoplasms were retrospectively evaluated across five institutions. Demographic, prenatal care, clinical presentation, histopathologic characteristics, operative and adjuvant therapies, and survival outcomes were collected.

RESULTS

323 patients met inclusion. The mean age at diagnosis was 1.5-years. Six patients were conceived through IVF. Eleven families reported abnormal prenatal ultrasounds, although only six were diagnosed prenatally. The most common histopathologies included low-grade astrocytoma (30.6%), ependymoma (15.8%), ATRT (11.5%), medulloblastoma (8.0%), and high-grade astrocytoma (2.8%). 48.9% of patients had low-grade neoplasms, and a third of patients (33.1%) had high-grade tumors. Patients commonly presented with hydrocephalus (59.1%), emesis (34.7%), ocular abnormalities (20.4%), macrocrania (18.0%), lethargy (14.6%), developmental delays (12.7%), and irritability (11.8%). All patients received surgical resection: 55.4% received gross-total (GTR) and 20.4% received subtotal resection. Concurrent treatment with adjuvant therapies occurred in a subset of patients, with 52.9% of patients receiving chemotherapy, 27.2% undergoing radiation, and 6.2% participating in a clinical trial. Patients with low-grade tumors had a rate of 88% progression-free (PFS) at 1-year, 74% PFS at 3-years, and 64% PFS at 5-years post-operative. Patients with high-grade neoplasms had worse PFS, with estimates at 59%, 40%, and 37% at 1-, 3-, and 5-years, respectively. There was statistically significant differences in PFS between patients with high- and low-grade neoplasms (p<0.0001).

CONCLUSIONS

This series consisted of very young pediatric patients across five participating institutions with diverse histopathologies that vary in frequency relative to the entire pediatric population. Lesions were rarely detected prenatally, despite their young age at diagnosis. GTR occurred in half of patients and subsequent management with adjuvant therapies was common in both sub-totally resected low-grade lesions and high-grade tumors.
METB-04. UTILITY OF OPTICAL GENOME MAPPING IN THE CHARACTERIZATION OF PAEDIATRIC CENTRAL NERVOUS SYSTEM TUMOURS: ANALYSIS OF A MONO-INSTITUTIONAL SERIES OF 26 CASES
Authors: alesi viola , Genovese Silvia , Russo Serena , Giovannoni Isabella , Barresi Sabina , Tancredi Chantal , Pedace Lucia , Lombardo Antonietta , Bontempo Piera , Agolini Emanuele , Calacci Chiara , Morgia Alessandra , Calvieri Giusy , Puggioni Chiara , Cardoni Antonello , Cacchione Antonella , Baldo Giada Del , Colafati Giovanna Stefania , Carai Andrea , Mastronuzzi Angela , Miele Evelina , Abeni Damiano , Locatelli Franco , Muda Andrea Onetti , Novelli Antonio , Alaggio Rita , Rossi Sabrina
Published: June 2024

BACKGROUND

Optical Genome Mapping (OGM) is a recent platform which enables the detection of genome-wide balanced and unbalanced structural rearrangements (SR), providing a genome complexity overview.

METHODS

This study explores OGM implementation in the context of paediatric central nervous system (CNS) tumours by analyzing a series of 26 cases.

RESULTS

OGM equaled Chromosomal Microarray Analysis in detecting aneuploidies and copy number alterations (CNA), and, although less sensitive than RNAseq in identifying gene-fusions (15/19), enabled the definition of their causative mechanism. The assessment of SR and CNA allowed the distinction of different groups. Amount and distribution of SR identified 4 groups: HIGH_SR with >10 breakpoints (BP) distributed in ≥5 chromosomes (8 cases), SR_CHROMOTHRIPSIS with ≥10BP in <5 chromosomes with the most affected chromosome presenting with >10 BP (9 cases), and LOW_SR with <10BP (9 cases). CNA non-associated with chromothripsis (nCthCNA) stratified the series in NO_nCthCNA, LOW_nCthCNA, INT_nCthCNA, HIGH_nCthCNA group, where the alterations were absent (9 cases), <10 (9 cases), 10-49 (2 cases) and ≥50 (6 cases), respectively. nCthCNA directly correlated with the mean number of chromosomes harboring SR, i.e. 10.2 in HIGH_/INT_nCthCNA vs 2.5 in NO_/LOW_nCthCNA (p=0.001), and inversely with chromothripsis (9/18 in NO_/LOW_nCthCNA vs 0/8 in HIGH_/INT_nCthCNA, p=0.015).

CONCLUSIONS

High complexity groups associated with biological aggressiveness, with HIGH_nCthCNA including only high-grade tumours (p=0.004) and disease progression mostly occurring in HIGH_SR (6/7 cases vs 1/17, p<0.001) and HIGH_nCthCNA (4/5 vs 2/12 cases, p=0.013). Low-complexity groups were enriched of low/intermediate-grade tumours (13/15 in NO_/LOW_nCthCNA vs 5/11 in INT_/HIGH_nCthCNA, p=0.024). SR_CHROMOTHRIPSIS cases were all low/intermediate-grade fusion-driven tumours, did not harbour TP53 mutations or high-impact CNA (0/9 vs 7/17, p=0.030), and did not progress (0/9 vs 7/16, p=0.030). This study suggests a possible value of OGM assessment of genome complexity in prognostication of paediatric CNS tumours.
METB-08. CIRCULAR EXTRACHROMOSOMAL DNA IS ASSOCIATED WITH POOR SURVIVAL IN CHILDHOOD CANCER TYPES
Authors: Sridhar Sunita , Chapman Owen , Dutta Aditi , Wang Shanqing , Kenkre Rishaan , Luebeck Jens , Bafna Vineet , Mesirov Jill P , Chavez Lukas
Published: June 2024

BACKGROUND

Circular extrachromosomal DNA (ecDNA) is a common form of oncogene amplification in aggressive cancers and a promising target for improved cancer therapy. The frequency and diversity of ecDNA has been described in different types of adult cancers and in selected childhood cancer types such as neuroblastoma and medulloblastoma. However, the frequency of ecDNA and its association with survival has not been comprehensively analyzed across the spectrum of pediatric cancers.

METHODS

We performed a pediatric pan-cancer study of ecDNA in which we mined large pediatric cancer genomics repositories and reconstructed ecDNA sequence structures from whole genome sequencing data.

RESULTS

We analyzed a retrospective cohort of 1684 tumor biopsies from 1506 different patients, covering all major childhood cancers, many of which occur exclusively in children, including rare embryonal tumor types. The fraction of patients with ecDNA-positive tumors was 10%, varying significantly by tumor type. Aggressive tumor types had particularly high incidences of ecDNA, including embryonal tumors with multilayered rosettes (n = 6, 67%), osteosarcoma (n = 55, 47%), rhabdomyosarcoma (n = 38, 39%), and neuroblastoma (n = 111, 30%). Survival analysis revealed that ecDNA amplifications are significantly associated with poor outcome. Furthermore, we catalogued known and potentially novel oncogenes that are recurrently amplified on ecDNA in pediatric cancers and showed that ecDNA often evolves during disease progression.

CONCLUSIONS

These results reveal childhood tumor types in which ecDNA is widely prevalent and highlight patient populations that could potentially benefit from future therapies targeting mechanisms of ecDNA biogenesis and function.