bluuebunny/crossref_metadata_2025 huggingface dataset:
HGG-50. Specific sensitivity of pediatric high-grade glioma with ATRX inactivation to PARP inhibitor combinations
Authors: Laemmerer Anna , Kirchhofer Dominik , Madlener Sibylle , Loetsch-Gojo Daniela , Jaunecker Carola N , Gabler Lisa , Mayr Lisa , Stepien Natalia , Baumgartner Alicia , Dieckmann Karin , Pfister Stefan M , Kool Marcel , Krausert Sonja , Gopisetty Apurva , Jäger Natalie , Peyrl Andreas , Azizi Amedeo A , Berger Walter , Gojo Johannes
Published: June 2022

Pediatric high-grade gliomas (pHGG) account for approximately 12% of pediatric brain tumors. Despite advances in molecular diagnosis and identification of discrete molecular subtypes, pHGG are the leading cause of cancer-related death in children. Thus, current research focuses on identifying novel therapeutic targets. Sequencing analyses across pediatric cancer types identified DNA repair perturbations as potentially targetable events in certain types of pediatric brain tumors. Herein, we investigated the potential of PARP inhibitors (PARPi), impeding the central role of PARP in DNA damage repair, in pHGG. We screened a patient-derived primary pHGG cell line panel (n=7) for their sensitivity towards 6 different PARPi (niraparib, olaparib, pamiparib, rucaparib, talazoparib, veliparib) using cell viability assays. Basal expression of DNA repair related proteins was assessed by immunoblot, and propidium iodide-based flow cytometry was used for cell cycle analysis. All pHGG were resistant towards single compound PARP inhibition. Interestingly, two H3F3A-G34R mutant pHGG models harboring inactivating ATRX mutations were characterized by elevated basal levels of pH2AX, suggesting increased stress resulting from DNA damage. Consequently, simultaneous targeting of PARP and other components of DNA repair in the respective models showed strong synergistic effects on cell viability, which was not observed to a comparable extent in other models such as BRAFV600E/TERT promotor mutant pHGG. Combination of talazoparib and irinotecan resulted in S-phase arrest. Within a precision oncology approach, we treated a 11-year-old child suffering from H3F3A-G34R mutant pHGG with ATRX mutation, that progressed during radiation, with niraparib and topotecan. The patient achieved partial remission and disease stabilization for 1 year. Taken together, PARPi combinations show potential for the treatment of pHGG with ATRX mutations. Currently, all cell models are characterized for DNA repair signatures by DNA sequencing. Further, in depth characterization of DNA damage responses upon concomitant PARP and topoisomerase inhibition in ATRX-mutated pHGG are ongoing.
HGG-53. "Profile of High Grade Gliomas and Diffuse Intrinsic Pontine Gliomas in Greek Pediatric Patients: an 8-year Single Institution's experience"
Authors: Roka Kleoniki , Filippidou Maria , Vlachou Antonia , Gavra Maria , Panagopoulos Dimitrios , Markogiannakis Georgios , Kokkinou Eleftheria , Alexopoulou Aikaterini , Chasiotou Maria , Sfakianos Georgios , Pons Roser , Stefanaki Kalliopi , Kattamis Antonis
Published: June 2022

BACKGROUND/OBJECTIVES: Aggressive clinical and biological behavior, high morbidity and mortality are the main characteristics of pediatric high-grade-gliomas (HGG). Our aim was to study patients (pts) with ΗGG or diffuse-intrinsic-pontine-glioma (DIPG), diagnosed in the largest pediatric neurooncology Center in Greece. DESIGN-METHODS: We performed a retrospective-review of newly-diagnosed pts with HGG or DIPG during 2014-2021. Gender, age, location, resectability, type of surgery, histological and molecular characteristics, management and outcome were analyzed. RESULTS: During the study-period, 38pts (18females), median age:9.35y(range:3days-16.9y), were diagnosed in our center. The most common tumor-location were pons (17/38 pts) and parietal lobe (11/38 pts). DIPG based on imaging-studies was diagnosed in 16pts.

Surgical approach was performed in 32pts (VP-shunt insertion:8, biopsy:12, partial resection:6, subtotal: 6). In 23pts(5 brainstem-tumors) a histological-diagnosis was feasible. Astrocytoma grIV was found in 60.8% and grΙΙΙ in 26.1%(14 and 6 respectively). Of notice, 3 additional pts with histological findings of low-grade(2grII and 1gr1), were upgraded in grIV after molecular-studies and DNA-methylation analysis. Furthermore, 17.3% of the pts (4/23, 3 located in the midline) carried a Η3Κ27Μ-mutation (diffuse midline glioma, DMG), 17.3% a Η3F3A-mutation and 8.6% showed ΕGFR-overexpression. All patients>3years of age were treated upfront according to HIT-HGG2013 with radiotherapy-temozolomide (29/32pts). In 5DIPG pts, reirradiation after disease-progression resulted in temporary symptomatic improvement. HGG-pts upon progression were treated with bevacizumab-irinotecan. Of the 38pts, 6pts elected to receive treatment in other countries. Overall-survival was 75.1%,15.1% and 3.7% at 1,2 and 3 years post-diagnosis respectively. Patients with DIPG/ DMG and non-midline HGG had a median overall-survival of 1.10 years and1.34 years, respectively. CONCLUSIONS: The experience of our unit concurs with worldwide published series and shows that pediatric HGG and DIPG have a dismal prognosis. Re-irradiation may offer short survival prolongation. ASKNOWLEDGEMENTS: Authors asknowledge the contribution of KiTZ-Heidelberg in molecular diagnostics through collaboration with ACCC.
IMG-06. Comparing between MR spectroscopy done at 1.5T and 3T
Authors: Tang Phua Hwee , Nisa Sameema
Published: June 2022

INTRODUCTION: In hospitals with heavily utilised MRI scanners, it may not be possible to schedule the patient on 1 particular scanner for all scans and thus this project was carried out to determine if there is any significant difference in the spectroscopy profile between 1.5 T and 3T MRI scanners late year 2021. AIM: To describe the MR spectroscopy profile of normal brain tissue performed on 1.5T and 3T MRI scanners in KK Women’s and Children’s Hospital. METHODS: Three healthy adult volunteers with normal body mass index underwent MRI brain scans after informed consent in this Institute Review Board approved study. MRI brain scans were performed on 1.5T General Electric MRI scanner and 3T Siemens Skyra MRI scanner 1 week apart. NAA/Cr, Cho/Cr and Cho/ NAA values were obtained from the right and left cerebral hemispheres.

RESULTS: Average NAA/Cr in the right cerebral hemisphere is 2.06+/-0.10 at 1.5T. Average NAA/Cr in the left cerebral hemisphere is 2.01+/-0.23 at 1.5T. Average NAA/Cr in the right cerebral hemisphere is 1.56+/-0.09 at 3T. Average NAA/Cr in the left cerebral hemisphere is 1.81+/-0.29 at 3T. Average Cho/Cr in the right cerebral hemisphere 1.06+/-0.14 at 1.5T. Average Cho/Cr in the left cerebral hemisphere is 1.11+/-0.22 at 1.5T. Average Cho/Cr in the right cerebral hemisphere is 0.90+/-0.05 at 3T. Average Cho/Cr in the left cerebral hemisphere is 0.95+/-0.27 at 3T. Average Cho/NAA in the right cerebral hemisphere is 0.51+/-0.06 at 1.5T. Average Cho/NAA in the left cerebral hemisphere is 0.58+/-0.00 at 1.5T. Average Cho/NAA in the right cerebral hemisphere is 0.55+/-0.05 at 3T. Average Cho/NAA in the left cerebral hemisphere is 0.52+/-0.07 at 3T. CONCLUSION: MR spectroscopy values obtained from 1.5T and 3T MRI scanners show no significant difference(P>0.05).
IMG-07. Contralateral transient contrast enhancement in a patient with IDH1wt MGMT promoter-methylated GBM responding to TMZ and individualized multimodal immunotherapy
Authors: Matiashchuk Andrii , Makalowski Jennifer , Bitar Michael , Van de Vliet Peter , Stuecker Wilfried , Van Gool Stefaan
Published: June 2022

Immunotherapy-induced MRI changes remain challenging when treating GBM patients with immunotherapy as part of a combined treatment. The iRANO criteria provide a decision-tree in order to avoid over- and under-treatment reactions when contrast-enhancing lesions become visible and should be interpreted. We report a 34-year female, 34 weeks pregnant, who presented with epilepsy, and was diagnosed with IDH1wt MGMT promoter-methylated GBM after biopsy. On MRI, the left occipital lesion was mostly cystic-necrotic with peripheral contrast enhancement, and crossed over the corpus callosum to the right. The volume was calculated as 64 cm³ (abc/2 formula). She was treated with radiochemotherapy and 12 TMZm cycles. Within each TMZ cycle 5 days of immunogenic cell death (ICD) therapy (5 injections with Newcastle Disease Virus and 5 sessions of modulated electrohyperthermia (Oncotherm 50 min 40-60 Watt) was added at days 8 to 12. After all chemo-/ICD-therapy we continued with active specific immunotherapy: two autologous mature monocyte-derived dendritic cell vaccines loaded with ICD therapy-induced serum-derived antigenic extracellular microvesicles and apoptotic bodies (IO-Vac®). One month after the second IO-Vac®, 17 months after diagnosis, a temporal right FLAIR-visible region showed expansion, and three months later also diffuse contrast enhancement, which was confirmed in a control scan one month later. The original tumor was meanwhile reduced to 16 cm³. However, in the last available scan, two months after the former, the contrast enhancement was disappeared, and the pathologic area on FLAIR was diminished. The original tumor size was reduced to 2 cm³, two year after first diagnosis. She showed allergic skin reactions to TMZ, which was covered with systemic histamine intake. There were no side effects related to multimodal immunotherapy. Transient MRI changes can be observed even in distance from the original tumor and can be interpreted as immune-mediated effects when the original tumor is responding.
IMG-10. Determining brain tumour grade non-invasively using a simplified MRI perfusion protocol: single-bolus, leakage-corrected dynamic susceptibility-contrast MRI
Authors: Withey Stephanie , MacPherson Lesley , Oates Adam , Powell Stephen , Novak Jan , Bailey Simon , Mitra Dipayan , Arvanitis Theodoros N , Khan Omar , Rose Heather E L , Worthinton Lara , Peet Andrew C
Published: June 2022

INTRODUCTION: Perfusion is associated with grade and survival in children’s brain tumours. Dynamic susceptibility-contrast (DSC-) MRI measures perfusion non-invasively, estimating relative cerebral blood volume (rCBV). We previously showed significant differences between pre-treatment rCBV in low- and high-grade tumours in a multicentre study. Contrast agent leakage from tumour vessels during acquisition affects rCBV accuracy. A contrast agent pre-bolus can be given but this can be challenging in a clinical environment, introducing variability. Alternatively, a single bolus can be administered with leakage correction applied when processing the data. We investigated pre-treatment rCBV values in a multicentre study without pre-bolus administration. METHODS: Thirty-six patients underwent pre-treatment DSC-MRI scans at 2 centres on 4 different scanners. Protocols were variable. Pixel-by-pixel contrast agent concentration time courses were analysed. Maps of uncorrected (rCBVuncorr) and leakage-corrected rCBV (rCBVcorr) were produced. Whole-tumour regions-of-interest were defined and median whole-tumour DSC-MRI parameters calculated. Patients subsequently underwent surgery / biopsy. Tumours were classified and graded. RESULTS: Twelve tumours were classified as low-grade; 24 as high-grade. Median whole-tumour rCBVuncorr was significantly higher in high-grade tumours than in low-grade tumours (1.628 vs -0.167, p<0.001). Median rCBV significantly increased in low-grade tumours following leakage correction (-0.167 to 1.072, p=0.007); there was no significant change for high-grade tumours. Using the median rCBVuncorr of 1.19 to differentiate between low- and high-grade tumours resulted in sensitivity and specificity of 75% and 100%, respectively; median 1.45 for rCBVcorr resulted in sensitivity and specificity of 67% and 100%, respectively. DISCUSSION: DSC-MRI measures of perfusion can distinguish between low- and high-grade paediatric brain tumours. Contrast agent leakage correction is essential for accurate measurement of rCBV. This is robust across multiple centres despite using multiple protocols. CONCLUSION: Pre-treatment multicentre perfusion MRI acquired with a single-bolus and contrast agent leakage correction can aid with differentiating between high- and low-grade paediatric brain tumours.
IMG-14. Cognitive deficits and altered functional network organization in pediatric brain tumor patients
Authors: Seitzman Benjamin , Anandarajah Hari , McMichael Alana , Dworetsky Ally , Coalson Rebecca , Dowling Anna , Mitchell Timothy , Olufawo Michael , Agamah Alikem , Butler Rachel , Jiang Catherine , Gu Hongjie , Dierker Donna , Barbour Dennis , Schlaggar Bradley , Strahle Jennifer , Limbrick David , Rubin Joshua , Shimony Joshua , Perkins Stephanie
Published: June 2022

INTRODUCTION: Survivors of pediatric brain tumors experience significant cognitive deficits from their diagnosis and treatment. Mechanisms of cognitive injury are poorly understood, and predictors of long-term outcome are lacking. Large-scale, distributed brain systems provide a window into brain organization and function that may yield insight into these mechanisms and outcomes. Recent evidence suggests that systems-level changes are related to cognitive performance across the lifespan. Here, we evaluated brain network architecture, cognitive performance, and brain-behavior relationships in pediatric brain tumor patients.

METHODS: Forty-nine patients (ages 7-18y.o.) with any brain tumor diagnosis underwent resting state functional Magnetic Resonance Imaging (rsfMRI) during regularly scheduled clinical visits. All patients were tested with the NIH Toolbox Cognition Battery. One-hundred thirty-nine age- and sex-matched typically developing children were used as controls. All data were processed to minimize artifactual sources of variance. Functional brain networks were created for each patient via rsfMRI data from 300 regions of interest that sample the whole brain. Multilinear models were implemented to examine brain-behavior relationships, while accounting for demographic and clinical factors.

RESULTS: Functional network organization was significantly altered in patients compared to controls (p<0.001). Network organization was more affected in patients who received whole-brain radiation therapy than those who did not (t=2.52, p<0.015). Patients demonstrated significant impairments in multiple domains of cognitive performance, e.g. attention (p<0.0001). Weak relationships were found between cognitive performance and network organization, none of which survived multiple comparison correction.

CONCLUSIONS: Brain network architecture is significantly altered in pediatric brain tumor patients. Whole-brain radiation was related to the largest changes. Most network and cognitive changes were significant with large effect sizes, yet brain-behavior relationships were weak. Our results suggest that systems-level changes in brain organization may provide insight into long-term changes in brain function in pediatric brain tumor patients.
IMMU-02. Targeted innovative antibody fragment-based immunotherapy for medulloblastoma
Authors: Niesen Judith , Krüger Christina , Kreuter Naomé , Haferkamp Undine , Pless Ole , Schüller Ulrich
Published: June 2022

Medulloblastoma (MB) is the most common malignant pediatric brain tumor accounting for ~20 % of childhood brain tumors. One third of all MB are characterized by constitutive activation of the Sonic Hedgehog (SHH)-signaling pathway. This tumor type shows overexpression of the epidermal growth-factor receptor (EGFR), which we detected in SHH-MB patient samples, transgenic SHH MB mouse models, and MB-cell lines. In contrast, non-neoplastic cells only express EGFR at low levels. Intensive radio-/chemotherapy often leaves the young patients with significant long-term burdens including problems in brain development and cognitive deficits. Thus, there is an urgent need to develop new targeted therapies that can prevent tumor recurrence without affecting healthy cells. We selected EGFR as a potential therapy target using EGFR-specific antibody fragments (scFvs) as part of immunoconjugates, namely bispecific T-cell engagers (BiTEs) and immunotoxins (ITs). Both, the EGFR-specific BiTEs and the ITs showed specific binding and cytotoxic activity in MB cells. Effector- and target-cell specificity was demonstrated via flow cytometry for the BiTEs. BiTEs and ITs selectively killed MB-tumor cells and showed pro-apoptotic effects without unspecific effects. Furthermore, preliminary results from an innovative hiPSC-based in vitro-BBB-model suggest, that the ITs are able to cross the BBB. Finally, by having a functional cloning- and expression system for the BiTEs and ITs available, target-scFvs can be easily exchanged by novel antigens or peptides to obtain additional targeted immunotherapies. Together, these results pave the way for preclinical in vivo experiments and future clinical trials in patients with SHH MB.
IMMU-10. TUMOR ASSOCIATED MYELOID CELLS DRIVE THE IMMUNOBIOLOGY OF HIGH RISK PEDIATRIC EPENDYMOMA
Authors: Griesinger Andrea , Riemondy Kent , Eswaran Nithyashri , Donson Andrew , Willard Nicholas , Paine Simon , Bowes Georgia , Rheaume John , Chapman Rebecca , Ramage Judith , Jackson Andrew , Grundy Richard , Foreman Nicholas , Ritzmann Timothy
Published: June 2022

Molecular profiling of pediatric ependymoma (EPN) has previously identified discrete neoplastic subpopulations, of which Mesenchymal EPN Cells (MEC) characterize Posterior Fossa A tumors (PFA). MECs are associated with tumor immunosuppression. Here we further characterize the EPN immune environment using single-cell sequencing, spatial phenotyping and cytokine analyses to better define infiltrating myeloid subpopulations. We hypothesize that neoplastic and myeloid cells interact to propagate an immune suppressive environment conferring resistance to traditional therapies. We delineated myeloid cell subpopulations from single-cell RNA-seq of 26 pediatric EPNs and validated them through deconvolution of bulk gene expression profiling (n=299). To define subpopulation spatial distribution, we interrogated a range of tumor and myeloid markers using multiplex immunofluorescence (mIF). Finally, using single-cell cytokine analyses, we gained further insight into myeloid subpopulation function. Eight distinct myeloid subpopulations were identified, relating to macrophages, microglia and monocytes. A subpopulation of cells with wound healing ontologies and characterized by TREM1 expression, demonstrated features of myeloid derived suppressor cells, including IL6/STAT3 pathway activation. We called these hypoxia-M. Like MEC neoplastic cells, hypoxia-M was associated specifically with PFA1 subgroup EPN in both single-cell and bulk tumor gene expression profiling (p<0.001). Additionally, the presence of MEC and hypoxia-M correlated strongly in gene expression (r2=0.92, p<0.001) and IHC analyses, where they co-located to borders between necrosis, blood vessels and viable tumor. Analysis using mIF (n=54) confirmed MEC/hypoxia-M co-location and highlighted that all types of immune cell corralled in significant numbers around areas of vasculature and necrosis. Single cell cytokine analyses demonstrated that hypoxia-M secrete IL-8 which, we hypothesize, amplify the pro-tumor phenotype in PFA1 tumor microenvironment. EPN is characterized by discrete myeloid cell subpopulations which contribute to the tumor microenvironment. Treatment strategies must focus on modifying this pro-tumor, immunosuppressive microenvironment to deliver more effective treatment for childhood ependymoma.
IMMU-16. Next-generation CAR T-cells targeting IL13RA2 and secreting IL-15 achieve durable tumour clearance in pre-clinical model of diffuse midline glioma
Authors: Hotblack Alastair , Wawrzyniecka Patrycja , Cheng Gordon Weng-Kit , Nannini Francesco , Pule Martin , Straathof Karin
Published: June 2022

T-cells engineered with a chimeric antigen receptor (CAR) to acquire tumour specificity provide a possible new treatment approach for childhood brain tumours. Durable clinical remissions have been achieved with CD19-directed CAR T-cells in refractory B-cell malignancies including control of leptomeningeal disease and parenchymal deposits. Early clinical data of CAR-T cells in adult glioblastoma and diffuse midline glioma (DMG) further support the rationale for development of CAR-T cell therapy for paediatric high-grade gliomas (pHGG) and other high-risk childhood brain tumours. IL13RA2 provides a suitable CAR target. It is expressed in the majority of pHGG including DMGs while expression is absent on normal (paediatric) brain tissue. Early results with CAR T-cell therapy for adult HGG has shown that IL13RA2 can be safely targeted, and potent anti-tumour activity is possible. However, responses are variable and ultimately transient. This is likely due to the immunosuppressive environment encountered by CAR T-cells at tumour sites which hampers persistent tumour-directed immunity. Here we develop a next generation CAR approach engineering T-cells with both a CAR and a cytokine signal which supports persistent anti-tumour immunity. We have generated novel IL13RA2-specific antibodies and used these to construct CARs. Using a functional screening approach assessing target-specific cytolytic function, T-cell proliferation and cytokine release, we selected the optimal IL13RA2-CAR design. Then, we generated a next generation CAR construct co-expressing inflammatory cytokine IL-15 with the IL13RA2-CAR. In a PDX model of DMG, T-cells transduced with IL13RA2-CARIL-15, in contrast to IL13RA2-CAR alone, induced long-term tumour clearance. Further in vitro testing of IL13RA2-CARIL-15 showed enhanced proliferation and resistance to immune-suppressive secreted factors such as TGF-β. In conclusion, co-expression of IL-15 with IL13RA2-CAR enhances CAR T-cell proliferation and in vivo persistence and achieves durable tumour clearance. IL13RA2-CARIL-15 is being translated into a phase I clinical trial for patients with DMG.
IMMU-17. Comprehensive immunological gene expression profiling of pediatric brain tumors
Authors: Levine Adrian , Nobre Liana , Milos Scott , Johnson Monique , Laxer Benjamin , Ryall Scott , Siddaway Robert , Tabori Uri , Hawkins Cynthia
Published: June 2022

Immunotherapy, predominantly through immune checkpoint inhibition (ICI), has had incredible success in treating some metastatic cancers, however, outside of rare cases of mismatch repair deficient (MMRD) gliomas, brain tumors have not had consistent responses to ICI. This can be attributed to a variety of factors including a low tumor mutation burden, lack of T cell infiltrates, and the CNS immune privilege. There are numerous strategies to target the tumor immune microenvironment (TIME) beyond ICI, include CAR-T cells, tumor vaccines, and myeloid cell modulation. The investigation of these depends critically on detailed characterization of the cell populations and interactions in the CNS TIME. We developed a 103 gene NanoString immune-oncology gene expression panel that includes markers reflecting selected cell types, therapeutic targets, and cellular pathways, as well as the 18-gene Tumor Inflammation Signature, a well validate biomarker for ICI response. We have used this to characterize over 500 brain tumors, including a diverse set of 227 pediatric low-grade gliomas (LGG), 86 MMRD gliomas, 47 diffuse intrinsic pontine gliomas (DIPG), 26 ependymomas, 36 medulloblastomas, 70 adult gliomas, and 35 non-tumor brain samples. Our results demonstrate a broad range of immunologic states, including within groups of tumors with the same genetic driver alteration. In pediatric LGG with BRAF V600E, there was clear histologic correlation with immune status, as glioneuronal tumors had substantial upregulation of T cell markers and regulatory genes, while diffuse astrocytomas had a near normal immune profile. In DIPG there was strong upregulation of macrophage markers, contradicting prior reports that have characterized these tumors as immunologically neutral. In a set of MMRD gliomas treated with ICI we identified several differentially expressed genes correlating with therapeutic response, including CCL4, CXCL9, and HGPD. In sum, this provides a characterization of diverse immune activation states across pediatric gliomas and other brain tumors.
IMMU-20. Effective CAR-T cell medulloblastoma therapy in an immunocompetent mouse model
Authors: Tsahouridis Rania , Lim Chaemin , Sokolsky Marina , Dotti Gianpietro , Gershon Timothy
Published: June 2022

Immunotherapy with chimeric antibody receptor (CAR) T cells is effective for previously incurable hematologic cancers and may transform treatment for refractory brain tumors. However, CAR-T cell therapy for solid tumors has not yet been as successful as for leukemias, and animal models are needed to improve implementation. At present, preclinical studies of CAR-T cell therapy for brain tumors have typically used exogenous tumors, xenografted into immunocompromised mice, because primary mouse brain tumors do not express antigens that match brain tumor-specific antigens in humans. To advance preclinical development of CAR-T brain tumor therapy, we engineered mice to develop medulloblastomas that express B7-H3, an antigen specifically expressed on human medulloblastomas and other pediatric brain tumors. We show that treating these tumors with B7-H3-directed CAR-T cells provokes anti-tumor responses both in vitro and in vivo. Administering B7-H3 CAR-T cells by intracranial injection increased the event-free survival time of mice with medulloblastoma, in a dose-dependent manner. CAR-T cell treatment was not curative as an isolated intervention, suggesting that cure will require pairing with surgical resection and additional adjuvant therapy. Our model presents new opportunities to study the mechanisms of CAR-T cell efficacy and recurrence in an immunocompetent host with intact vasculature and blood-brain barrier. Our ongoing studies using scRNA-seq will allow us to define therapy-induced changes in tumor cells, CAR-T cells and cells of the tumor microenvironment and to test new T-cell modifications and combinations of therapeutic modalities, toward a goal of optimizing CAR-T cell therapy for pediatric brain tumors.
LGG-03. Pediatric spinal deformities concomitant with spinal cord pilocytic astrocytoma
Authors: Kapitancuke Monika , Rutkauskaite Vilma , Zagorskis Rimantas , Bernotavicius Giedrius , Lapteva Ona , Rascon Jelena
Published: June 2022

INTRODUCTION: Childhood spinal cord tumours may lead to spinal deformity. Rapid scoliosis progression, a left thoracic curve and early onset scoliosis are associated with an increased risk of intraspinal anomalies, therefore magnetic resonance imaging (MRI) should be performed. CASE PRESENTATION: A 1-year-old girl presented with progressive early onset scoliosis. MRI of the spine showed diffuse intramedullary lesion at vertebral level T5 – T11 and abnormal curvature of the thoracic spine to the right – 39-degree Cobb angle, after a few moths – 71-degree. Blood and cerebrospinal fluid examination ruled out a neuroinfection and autoimmune diseases. Histology revealed BRAF V600E-mutant pilocytic astrocytoma (PA) (IDH non-mutant), DNA methylation profiling – PA, MGMT promoter methylation – not detected, SNP-A karyotyping – normal. Treatment with weekly vinblastin was started due to non-operable tumour and progressive scoliosis. Spinal deformity was managed using serial casting with only mild correction of curvature. In the second case report, a 14-year-old boy either presented with progressive scoliosis. Spine x-ray showed abnormal curvature of the thoracic spine to the left - 89-degree Cobb angle and after a few years - 120-degree. MRI of the spine detected intramedullary tumour masses located at vertebral level T3-T5. Surgical resection revealed BRAF V600E-mutant PA (IDH, ATRX, TERT non-mutant), DNA methylation profiling – PA, MGMT promoter status – not methylated, SNP-A karyotyping – non-specific trisomy of chromosome 5. The patient was followed-up by routine spine MRI. However, after 8 months new spinal cord masses appeared. It was decided to correct scoliosis only after the total tumour removal. CONCLUSIONS: Intramedullary spinal tumours are overall rare in the pediatric population. Of these, PA accounts for the majority, however treatment remains challenging. BRAF V600E mutation has relatively high frequency in PA. This mutation identification opens more treatment options such as targeted therapy with BRAF V600E and MEK inhibitors for progressive disease.
LGG-04. Clinical and molecular characterization of metastatic pediatric low grade gliomas
Authors: Lindsay Holly , Stuckert Austin , Chintagumpala Murali , Su Jack , Baxter Patricia , Okcu M Fatih , Malbari Fatema , Rednam Surya , Reuther Jacquelyn , Fisher Kevin , Scollon Sarah , Plon Sharon , Roy Angshumoy , Parsons D Will , Lin Frank
Published: June 2022

BACKGROUND: Despite being the most common central nervous system tumor in children, ≤5% of pediatric low grade gliomas (pLGG) present with metastases. Due to their rarity, there is a paucity of clinical and molecular data in metastatic pLGGs. To address the need, we analyzed a cohort of 22 patients with pLGG followed at Texas Children’s Hospital who presented with metastatic disease. RESULTS: The predominant histology was pilocytic astrocytoma (16/22, 73%); average age at diagnosis was 4 years 11 months. The most common sites of primary disease were optic pathway/chiasm (7/22, 32%) and suprasellar (5/22, 23%). Metastatic disease was most commonly noted in the leptomeninges (12/22, 55%). 16/22 patients (73%) were treated with up-front medical therapy following tumor biopsy/resection, the majority with carboplatin-based therapy; the remaining 6 patients received only surgery up-front. Only 2/22 patients (9%) did not progress after their initial treatment with an average follow-up of 42 months. 14 patients (14/22, 64%) had continued disease progression after at least 2 therapeutic interventions; however, only 3 patients (3/22, 14%) eventually received craniospinal radiation. 10 patients (10/22, 45%) received treatment with an agent targeting the mitogen-activated protein kinase (MAPK) pathway. 20/22 patients (91%) were alive at last follow-up (average 72 months). 4/21 patients (19%) harbored a BRAF V600E mutation while 7/20 (35%) had a BRAF::KIAA1549 duplication/fusion. 8/20 patients (40%) were wildtype for both analyzed molecular alterations in BRAF. 8 patients had germline whole exome sequencing performed and all were negative for pathogenic/likely-pathogenic variants related to their clinical phenotype. Methylation analyses are pending on patients with available tumor tissue. CONCLUSION: In our cohort of patients with metastatic pLGG, most tumors progressed despite numerous therapeutic regimens, but the overall survival was >90%. 40% of patients were wild type for the 2 most common MAPK alterations seen in pLGG.
LGG-15. Late mortality and morbidity of adult survivors of childhood glioma treated across three decades: a report from the Childhood Cancer Survivor Study
Authors: de Blank Peter M K , Lange Katharine R , Xing Mengqi , Salehabadi Sedigheh Mirzaei , Srivatava Deokumar , Brinkman Tara M , Ness Kirsten K , Oeffinger Kevin C , Neglia Joseph , Krull Kevin R , Yasui Yutaka , Nathan Paul , Howell Rebecca , Turcotte Lucie , Leisenring Wendy , Armstrong Gregory T , Bowers Daniel C , Okcu M Fatih
Published: June 2022

PURPOSE: Pediatric low-grade glioma therapy has evolved to delay or eliminate radiation. The impact of therapy changes on long-term outcomes remains unknown. METHODS: Cumulative incidence of late mortality (death >5 years from diagnosis), subsequent neoplasms (SNs), and chronic health conditions (CHCs, CTCAE grading criteria) were evaluated in the Childhood Cancer Survivor Study among 5-year survivors of glioma diagnosed 1970-1999. Outcomes were evaluated by diagnosis decade and by treatment exposures received ≤5 years following diagnosis (surgery-only, chemotherapy ± surgery, and cranial radiation ± surgery or chemotherapy). Relative risk (RRs) with 95%CIs estimated long-term outcomes using multivariable piecewise exponential models. RESULTS: Among 2,684 eligible survivors (age at diagnosis (median [range]), 7 years [0-20 years]; time from diagnosis, 24 years [5-48 years]), exposure to cranial radiation decreased [51% (1970s), 45% (1980s), 25% (1990s)] along with late tumor recurrence (>5 & ≤15 years from diagnosis) [9.8% (1970s), 8.8% (1980s), 5.0% (1990s)]. The 15-year cumulative incidence of late mortality was 10.3% (1970s), 6.5% (1980s), and 6.0% (1990s) (p<0.001, comparison of cumulative incidence curves). The 15-year cumulative incidence of grade 3-5 CHCs was 19.7% (1970s), 17.8% (1980s), and 14.2% (1990s) (p<0.0001). A reduction in SN incidence was not observed. In multivariable analyses excluding treatment exposure, later diagnosis (1990s vs. 1970s) was associated with lower risk of late mortality, grade 3-5 CHCs and SNs. Inclusion of treatment exposure in the model attenuated the effect of diagnosis decade. Radiation or chemotherapy exposure increased risk compared to surgery alone for late mortality (radiation RR 4.95, 95%CI 3.79-6.47; chemotherapy RR 2.88, 95%CI 1.85-4.48), CHCs (radiation RR 4.02, 95%CI 3.28-4.94; chemotherapy RR 1.66, 95%CI 1.13-2.45), and SNs (radiation RR 4.02, 95%CI 3.06-6.13, chemotherapy RR 2.08, 95%CI 1.03-4.23)). CONCLUSION: Late mortality and CHCs decreased in childhood glioma survivors diagnosed from 1970-1999 largely due to therapy changes, particularly avoidance of cranial radiation, without increased late recurrence.
LGG-33. A 40-year cohort study of evolving hypothalamic dysfunction in 90 infants and young children (<3y) with optic pathway gliomas
Authors: Picariello Stefania , Cerbone Manuela , D'Arco Felice , Gan Hoong-Wei , O’Hare Patricia , Aquilina Kristian , Opocher Enrico , Hargrave Darren , Spoudeas Helen Alexandra
Published: June 2022

BACKGROUND: Despite high survival, paediatric optic pathway hypothalamic gliomas are associated with significant morbidity and late mortality. Those youngest at presentation have the worst outcomes. METHODS: We aimed to assess presenting disease, tumour location and treatment factors implicated in the evolution of neuroendocrine, metabolic and neuro-behavioural morbidity in children diagnosed before their 3rd birthday and followed over four decades (1981- 2020). RESULTS: Ninety infants/young children followed-up for 9.5 years (range 0.5-25.0) were included in the study. Fifty-two (57.8%) patients experienced endo-metabolic dysfunction (EMD), the large majority (46) had hypothalamic involvement (H+) and lower endocrine event free survival (EEFS) rates. Median time to first endocrine event was 3.4 years, with EEFS declining up to 13.6 years after diagnosis. EMD was greatly increased by a diencephalic syndrome presentation (85.2% vs 46%, p=0.001), H+ (OR 6.1 95% CI 1.7 – 21.7, p 0.005), radiotherapy (OR 16.2, 95% CI 1.7 – 158.6, p=0.017) and surgery (OR 4.8 95% CI 1.3- 17.2, p=0.015), all associated with anterior pituitary disorders. Obesity occurred in 25% of cases and clustered with the endocrinopathies. Posterior pituitary disorders were recorded in 15 subjects (16.7%), only after surgery and/or as a consequence of hydrocephalus in those with suprasellar tumours and hypothalamic disease. Neuro-behavioural deficits occurred in over half (52) of the cohort and were associated with H+ (OR 2.5 95% C.I. 1.1 – 5.9, p=0.043) and radiotherapy (OR 23.1 C.I. 2.9 – 182, p=0.003). CONCLUSIONS: Very young children with OPHG carry a high risk of endo-metabolic and neuro-behavioural comorbidities which deserve better understanding and timely/parallel support from diagnosis to improve outcomes. These evolve in a complex hierarchical pattern overtime whose aetiology appears predominantly determined by injury from the hypothalamic tumour location alongside adjuvant treatment strategies.
LGG-36. Analysis of BRAF-related mutations in pediatric low-grade glioma
Authors: Li Shaoqun , Lai Mingyao , Cai Linbo
Published: June 2022

BACKGROUND: Most pediatric low-grade gliomas (pLGGs) are driven by a single genetic event resulting in up-regulation of the RAS/MAPK pathway. BRAF-related mutations are the most freauent molecular alteration in the pathway. To explore BRAF-related mutations in pediatric low-grade glioma is helpful for clinical practice. METHODS: In this study, patients with low-grade glioma aged ≤18 years in Guangdong Sanjiu Brain Hospital were enrolled. All patients accepted the tests of BRAF-related mutations with tumor tissue by next-generation sequencing (NGS). Results: A total of 26 patients diagnosed low-grade glioma and underwent NGS detection were included in this study. The male to female ratio was 6:7, and the median age was 9.5 years. 8 patients had tumors located in the cerebral hemisphere, 6 in the third or fourth ventricle, 5 in the cerebellum, 4 in the optic pathway, and 3 in the brain stem. A total of 14 patients took BRAF-related mutations, such as BRAF-KIAA1549 fusion, BRAF p.V600E mutation and other fusion. BRAF-KIAA1549 fusion was detected in 7 patients with pilocytic astrocytoma or pilomyxoid astrocytoma. BRAF p.V600E mutation was detected in 6 patients, two of whom were pleomorphic xanthoastrocytoma. A rare genetic fusion, BCAS1-BRAF fusion, was detected in 1 patient who had brain stem ganglioglioma. Among the 26 patients, 2 patients without BRAF-related mutations had typical multiple cafe-au-lait macules and were diagnosed as NF1-pLGG. These patients were treated with surgery, radiation, chemotherapy and targeted therapy. Only 2 patients received targeted therapy by Trametinib, Vimofinib and Everolimus after progression of the tumor. However, due to the severity of the disease, they eventually died. CONCLUSIONS: More than half of pLGG patients have BRAF-related mutations, which have the opportunity for targeted therapy. However, the optimal timing of targeted therapy still needs further exploration.
LGG-39. Ascites in a medullary and leptomeningeal ganglioglioma patient following cisplatin treatment necessitating cessation of therapy and conversion to VA shunt
Authors: Cantor Evan , Ogle Andrea , Meyer Ashley , Shatara Margaret , Brossier Nicole M , Abdelbaki Mohamed S , Strahle Jennifer , Cluster Andrew
Published: June 2022

INTRODUCTION: Ganglioglioma is a low grade neoplasm consisting of dysplastic neuronal and neoplastic glial cells and accounts for 5% of pediatric CNS tumors. Management often includes CNS diversion. There have been case reports in which platinum containing chemotherapy has been thought to contribute to CSF malabsorption leading to ascites. CASE: A 13 month old male developed progressive macrocephaly, developmental delay, chronic emesis, and intermittent bilateral cranial nerve VI palsy over the 5 months prior to presentation. MRI brain/spine was significant for an enhancing nodule in the left posterior lateral medulla, nodular thickening and enhancement along the brainstem down to the conus medullaris and in the tentorium, with associated hydrocephalus. Biopsy of the medullary nodule and of the enhancement were consistent with ganglioglioma with BRAF-KIAA1549 fusion, equivocal MYCN amplification, and no BRAF V600E mutation. A ventriculo-peritoneal shunt was placed at the time of biopsy. Therapy was initiated with vincristine (1.5 mg/m2) and carboplatin (175 mg/m2.) Following the 12 week induction phase of therapy, he developed increasing diarrhea, emesis, and abdominal ascites. Peritoneal fluid analysis had no malignant cells and low protein compared to CSF. Ascites was responsive to drainage but would rapidly re-accumulate. Ultimately the patient’s chemotherapy was discontinued after 2 maintenance cycles due to continued symptoms. Acetazolamide was trialed but discontinued due to side effects, so its efficacy could not be determined. He underwent shunt externalization followed by venticulo-atrial (VA) shunt re-internalization. He has not had ascites since that time, at 4 months from surgery. His CNS disease burden has been stable at 6 months off therapy. DISCUSSION: Ascites was most likely due to CSF malabsorption in the abdomen with a possible contribution from platinum containing chemotherapy and less likely secondary to malignant peritoneal cells. Resolution since VA shunt internalization makes alternate explanations less likely.
LGG-40. Growth hormone replacement in children on therapy with Vemurafenib for Low Grade Glioma
Authors: Verrico Antonio , Crocco Marco , Casalini Emilio , Ramaglia Antonia , Rossi Andrea , Iurilli Valentina , Piccolo Gianluca , Milanaccio Claudia , Garrè Maria Luisa , Iorgi Natascia Di
Published: June 2022

BRAF inhibitors (iBRAF) are a therapeutical option for pediatric Low-Grade-Gliomas (pLGG), but their chronic use may be needed to prevent tumor regrowth. Growth hormone (GH) replacement in children with GH deficiency (GHD) and on oncological treatment is under debate. We report on our experience of recombinant human GH (rhGH) replacement in two children (1 Female, 1 Male) which started Vemurafenib therapy, at 5 (F) and 9,25 (M) years of age, for recurrent/progressive chiasmatic-hypothalamic pLGG, with partial response (RANO criteria) and subsequent stable disease. A diagnosis of GHD was established at 9,2 (F) and 11,2 (M) years of age (GH peaks to stimulation tests <3mcg/L), 4,2 (F) and 1,9 (M) years after Vemurafenib start. Both patients were treated with GnRH analogues for precocious puberty. rhGH dose was titrated to 0.020 mg/kg/day during follow-up based on IGF-1 levels < +2 SDS. Height remained stable in both (F: -3,4SDS; M: 0SDS), with a mean growth velocity after 2 years around 6 cm/yr. BMI increased in the F (1,59 to 1,78 SDS) and decreased in the M (2,66 to 2,56 SDS); Dual-X-ray absorbiometry confirmed high fat mass at T0 (F:54,6%; M:48%) and at T24 (F:49,2%; M:48,1%). Lipid profile improved in both patients (F: Triglycerides 175 to 152 mg/dl, LDL 195 to 155 mg/dl; M: Triglycerides 138 to 118 mg/dl, LDL 147 to 147 mg/dl, at T0 and T24, respectively), while baseline blood glucose increased (F: 83 to 96 mg/dl; M 82 to 91 mg/dl). Residual tumor was stable in both patients. CONCLUSIONS: In 2 GHD patients due to pLGG and treated with Vemurafenib, two-years of low-dose rhGH showed beneficial effects on height stabilization and on lipid profile, and a different impact on body composition parameters; rhGH was safe and not associated with residual tumor growth.
LGG-43. Reduction in the cerebrospinal fluid protein level after bevacizumab treatment in patients with optic pathway low-grade gliomas
Authors: Dassi Natália , Cappellano Andrea , Costa Marcos , Watanabe Rodrigo , Soares Carolina , Silva Frederico , Almeida Daniela , Dastoli Patricia , Nicacio Jardel , Cavalheiro Sérgio , Saba Nasjla
Published: June 2022

Cases Presentations: Case 1: A 1-year-old boy with suprasellar pilocytic astrocytoma with previous history of shunting disfunction, treatment according vinblastine protocol due to anaphylactic reaction with carboplatin presented with ascites and necessity of ventricular-atrial shunt. Due to high protein cerebrospinal fluid (CSF) level (551mg/dl) he was submitted to external ventricular drainage and bevacizumab 10mg/kg was associated to his oncology treatment. After three cycles of bevacizumab, the patients’ CSF protein levels decreased dramatically 178 mg/dL, allowing the shunt procedure without complications and shorter hospital stay. Case 2: A ten-year-old boy with suprasellar pilocytic astrocytoma treated with three lines of chemotherapy showed tumor progression one year after the end of carboplatin-vincristine protocol and shunting disfunction. External ventricular drainage was performed, and the CSF showed 590mg/dl protein level. He was treated with vinblastine 6mg/m2 weekly and bevacizumab 10mg/kg each 14 days. After two cycles of bevacizumab, the protein level was 191mg/dl allowing another V-P shunt procedure. Discussion: Optic pathway gliomas frequently cause elevated cerebrospinal fluid protein concentrations leading to shunts occlusions and failures, necessity of external ventricular drainage and longtime hospitalization, implicating risk of serious infections. Bevacizumab is a monoclonal antibody with immunomodulatory and anti-vascular endothelial growth factor (VEGF) activities that has been used in combination with other chemotherapeutic agents such as irinotecan and vinblastine to treat low-grade gliomas and has been reported to decrease the CSF protein concentration.Final Comments: Bevacizumab treatment in patients with gliomas and high CSF protein levels seems effective in decreasing protein leakage from the vessels to the ventricles, thereby improving the scope for successful shunt placement.
LGG-48. The influence of different FGFR1 alterations on pediatric low-grade glioma tumor biology and targeted therapy response
Authors: Morin Eric , DiGiacomo Jeromy , Novikov Dana , Malinowski Seth , Chow Kin-Hoe , Jones David , Alexandrescu Sanda , Ligon Keith , Bandopadhayay Pratiti
Published: June 2022

Pediatric low-grade gliomas (pLGGs) have excellent survival, however, with current standard of care, most patients suffer lifelong severe sequalae. pLGGs are almost exclusively driven by single activating mutations in the MAPK pathway. Clinical trials with small molecule inhibitors in BRAF-altered pLGGs are showing promising results in early clinical trials, and similar efforts are now underway for FGFR1-altered tumors, however the underlying biology and treatment response has not been thoroughly explored in a pre-clinical setting. To explore the genetic landscape of FGFR altered gliomas we assembled a cohort of 87 patients with FGFR1-4 altered gliomas across Dana-Farber Cancer Institute, Boston Children’s Hospital and Brigham and Women’s Hospital. Within this cohort we observed that pLGGs harboring FGFR1 kinase hotspot mutations (FGFR1-N546K or -K656E) frequently harbored a second alteration associated with activation of the MAPK or mTOR pathways, most commonly in the phosphatase PTPN11, NF1 or within the FGFR1 gene itself. Additionally, we observed two previously described structural variants of FGFR1, an FGFR1 internal kinase tandem duplication (FGFR-ITD) and a fusion with TACC1 (FGFR1:TACC1). The relative impact of the different FGFR1 alterations on oncogenicity, therapeutic response and resistance has not been previously explored. To address this, we have established mouse neural stem cell models overexpressing the structural variants and hot spot mutant FGFR1 alone or in combination with a second alteration. Immunoblotting revealed that the addition of a second alteration attenuated phosphorylation of ERK, AKT and S6 and influenced cell proliferation both in normal growth conditions and in absence of growth factor. Treatment with inhibitors of FGFR (Infigratinib) and MEK (Trametinib) revealed variable sensitivity both targeted therapies, suggesting that treatment of FGFR1 driven pLGG might require tailoring to the specific FGFR1 alteration.