bluuebunny/crossref_metadata_2025 huggingface dataset:
LINC-10. The Adequate Treatment of Children and Adolescents with Primary Central Nervous System Germ Cell Tumors (CNS GCT) in a Developing Country
Authors: Cappellano Andréa M , Dassi Natalia , Mançano Bruna , Epelman Sidnei , Almeida Daniela B , Cavalheiro Sergio , Dastoli Patricia A , Seixas Maria Teresa , Nicácio Jardel M , Costa Marcos D , Silva Frederico A , Aguiar Simone S , Almeida Jr Carlos R , Teixeira Gustavo R , Silva Nasjla S , Finlay Jonathan L
Published: June 2022

INTRODUCTION: Primary central nervous system germ cell tumors (CNS GCT) are a heterogeneous group of malignancies that can be divided into germinomas and non-germinomatous GCT (NGGCT), accounting for 2-3% of brain tumors in children/adolescents in the Western hemisphere. The study aim is to report the ability to adequately treat Brazilian patients with CNSGCT through a consortium protocol, reporting their treatment, response and survival. Methods: Since 2013, 58 patients with histologic and/or tumor marker (TM) diagnosis of germinoma with/without HCGβ levels ≤200mIU/ml (n=43), five of them between 100-200mIU/ml, received carboplatin/ etoposide (4 cycles) and NGGCT (n=15), received carboplatin/etoposide/cyclophosphamide (6 cycles), all followed by 18Gy ventricular field irradiation and primary site(s) boost. Autologous hematopoietic cell transplant (AuHCT) was undertaken for NGGCT slow responders. Results: Mean age 13.2 years, 42 males. Diagnosis was made by TM (n=19), surgery (n=25) and both (n=12). Two bifocal cases with negative TM and inconclusive biopsy were treated as germinoma. Primary tumor location was pineal (n=30), suprasellar (n=16), bifocal (n=11) and basal ganglia/thalamus (n=1). Eighteen had ventricular/spinal spread. Second-look surgery occurred in seven patients. For the germinoma group, 36 achieved complete responses (CR) after chemotherapy, seven showed residual teratoma/scar. For the NGGCT after 4/6 cycles, six patients showed CR, two failure/progression and seven partial responses (five with negative TM). Two with positive TM underwent AuHCT. Radiotherapy was utilized as described, except in three patients. Four NGGCT patients died (two disease progression, two other causes with no disease). Toxicity was mostly grade 3/4 neutropenia/thrombocytopenia during chemotherapy. At a median follow-up of 40 months, event-free and overall survival was 100% for germinoma and 64.5% NGGCT. Conclusion: The proposed treatment was feasible to be performed in a developing country, with suitable survival even with VFI dose reduction to 18Gy.
LINC-14. A single center retrospective analysis of pediatric pineoblastoma in Beijing
Authors: Li Miao , Du Shuxu , Sun Yanling , Wang Shumei , Wu Wanshui , Sun Liming
Published: June 2022

OBJECTIVE: To explore the clinical characteristics and outcome in children with pineoblastoma in Beijing. METHODS: Clinical data of 18 pediatric patients with newly diagnosed pineoblastoma admitted to Beijing Shijitan Hospital between January 2014 and November 2021 were retrospectively analyzed. The diagnoses were confirmed by pathology. RESULTS: Male/female ratio=8:1. The median age at diagnosis was 4.7 (range, 0.2-12.6) years, with 2 cases in infancy, and 13 cases ≥ 3 years. The symptoms at diagnosis included headache (31%), vomiting (29%), convulsions (9%), strabismus (9%), nausea (6%), etc. Four patients experienced metastasis at diagnosis. Ki-67 index was under 30% in 5 cases, 30-80% and ≥80% in 10 and 2 cases, respectively. All were treated with surgery, and 12 children underwent gross total resection (GTR). Seventeen cases were administered both radiotherapy and chemotherapy, with one case only radiotherapy followed by surgery. Median follow-up time was 54 months. Nine patients developed a recurrence and 2 patients died at last follow-up. The 1-year/3-year progression-free survival (PFS) and overall survival (OS) were (77.8±10.5/11.1±10.5)%, and (100/90.9±8.7) %, respectively. The 3-year OS of boys (93.8%) was higher than that of girls (50.0%); and also higher in cases with GTR (91.7%) than STR (83.3%). However, the differences were not significant in the above two groups. The children with Ki-67 index ≥80% had worse 3-year OS than those<80% (χ2=8.000, P=0.005). The median PFS of children treated under the order of craniospinal irradiation followed by chemotherapy was better than that of the inverse order (29m vs 13m, χ2=6.528, P=0.011).CONCLUSION: Pineoblastoma is rare and often fatal, but with better OS in our center, although the PFS is dismal. Boys, GTR resections, and Ki-67 index <80% tends to have better OS, and the order of irradiation followed by chemotherapy tends to have better PFS.

Keywords: pineoblastoma; therapy; survival
LINC-15. Sustaining multidisciplinary care of children with central nervous system tumors during the COVID-19 pandemic
Authors: Richelle Ong Faustine , Baticulon Ronnie , Alcasabas Ana Patricia
Published: June 2022

INTRODUCTION: A multidisciplinary team (MDT) approach is essential for quality cancer care. Since 2019, we have conducted regular MDT meetings to discuss pediatric patients with central nervous system (CNS) tumors at the Philippine General Hospital. Because of COVID-19, an abrupt transition from in-person to virtual meetings became necessary. METHODS: We reviewed the proceedings of MDT meetings for pediatric CNS tumors from March 2020–December 2021. We identified the strategies and adaptations of our pediatric neuro-oncology group, and outlined recommendations for other institutions in low- and middle-income countries. RESULTS: Our pediatric neuro-oncology group conducted 18 virtual MDT meetings during the study period. Meetings were scheduled every last Tuesday of the month, with pediatric oncologists, neurologists, neurosurgeons, radiation oncologists, radiologists, and neuropathologists regularly attending. We invited other specialists as needed. In total, we had 135 case discussions for 79 unique patients, or about 8 patients per meeting. These included both inpatients (74%) and outpatients (26%). Ten patients received prior treatment elsewhere. At the time of the meeting, 86% were postoperative, 8% were preoperative, and 6% did not require surgery. Most (60%) had malignant CNS tumors and 15% had disseminated/leptomeningeal disease. Histopathologic diagnosis was obtained for 62 patients (79%). Concerns addressed were: formulating a treatment plan (88%), surveillance strategy (10%), and diagnostic workup (5%). DISCUSSION: Several factors contributed to the ease of online transition: (1) motivated care providers including a patient navigator, (2) fixed schedule, (3) institutional Zoom account for securing data privacy, and (4) availability of picture archiving and communication system (PACS) for neuroimaging. Challenges included: (1) delays due to internet connectivity, (2) Zoom fatigue and online distractions, and (3) risk for miscommunication or misunderstanding. Commitment of the entire neuro-oncology team is essential to ensure the delivery of best possible care for pediatric patients with CNS tumors.
LINC-18. Challenges in the neurosurgical care of pediatric patients with central nervous system tumors during the COVID-19 pandemic
Authors: Paul Golidtum Jared , Custodio John Emmanuel , Estanislao Jochrys , Alcazaren Jose Carlos , Seng Kenny , Navarro Joseph Erroll , Baticulon Ronnie
Published: June 2022

INTRODUCTION: Central nervous system (CNS) tumors account for 20 - 30% of all childhood cancers. The Philippines is a lower-middle income country, wherein brain centers are located mostly in urban areas. We aimed to identify challenges that pediatric patients with CNS tumors encountered during the COVID-19 pandemic, which aggravated delays in their diagnosis and treatment. METHODS: This is a retrospective review of all pediatric patients who underwent neurosurgery for CNS tumors at the Jose R. Reyes Memorial Medical Center, a tertiary referral center, from January 2020 until December 2021. We summarized patients’ demographic data, clinical course, and perioperative outcomes. RESULTS: A total of 38 pediatric patients underwent neuro-oncologic surgery in our center during the study period. There were 18 males and 20 females, with a mean age of 7.5 ± 4.9 years. Tumor was biopsied and/or resected in 35 cases (92%). The most common histologic diagnoses were medulloblastoma (n=8, 21%) and high-grade glioma/glioblastoma (n=5, 13%). Median preoperative length of stay and total length of stay were 10 (IQR: 17) and 28 (IQR 33.75), respectively. There was a high perioperative mortality rate in 2020 (71%), but this decreased to 20% in 2021. Six patients (16%) developed COVID-19 infection during the perioperative period. There were nine patients (24%) who had documented tumor progression because of delays in adjuvant therapy. DISCUSSION: Aside from geographic barriers and catastrophic health expenditure, the major challenges that disrupted the care of pediatric patients with CNS tumors in our center during the COVID-19 pandemic were delays in neuroimaging for diagnosis, unavailability of operating room slots, deficiency in critical care beds, and workforce shortage due to COVID-19 infection among health workers. Health care systems must adapt to the changes brought about by the pandemic, so that children with CNS tumors are not neglected.
LINC-24. Survival and genetic evaluation of patients diagnosed with choroid plexus tumor treated at a Brazilian institution
Authors: Oliveira Milena , Silva Nasjla , Cappellano Andrea , Rodrigues Jessica , Almeida Daniela , Cavalheiro Sergio , Dastoli Patricia , Silva Frederico , Seixas Maria Teresa , Lima Fernanda
Published: June 2022

INTRODUCTION: Choroid plexus tumors (CPT) are rare intraventricular neoplasms of epithelial origin. They usually occur in the 2nd year of life, corresponding to 0.4-0.6% of intracranial tumors in this age group. They are classified, according to WHO 2021: choroid plexus carcinoma (CPC), atypical choroid plexus papilloma (ACPP) and choroid plexus papilloma (CPP). Li-Fraumeni syndrome (LFS) is present in 50% of patients with CPC. In Brazil, the TP53p.R337H mutation affects 0.3% of the population in the South/Southeast. OBJECTIVE: Evaluate the genetic assessment and overall-survival (OS) of patients with CPT treated at IOP/GRAACC/UNIFESP. PATIENTS/METHODS: Between 1995-2021, 48 patients were diagnosed with CPT in our institution, 27 CPC, 18 CPP and 3 ACPP. From 2012-2021 patients were referred for genetic evaluation, 16 of which had CPC (2 had previously CPP). Family history for neoplasms was present in 87.5%, 37.5% compatible with Li-Fraumeni Syndrome (LFS) of which 50% with positive mutations. The molecular investigation of TP53 gene in patients with CPC was performed and positive in 62,5%:R337H(6 patients), R110C*, R158H*, H179R*, R196* (*1 patient each). For those with R337H, p53 protein immunohistochemistry resulted in 90-100% positivity. Treatment strategies consisted of surgery with gross total resection being achieve in all ACPP, 94,4% CPP and 55,5% CPC. Chemotherapy was performed in only 1 case of ACPP and all CPC with a variety of schemas, including high dose of chemotherapy and autologous bone marrow transplant for slow responders or recurrent disease. The three- and five-years OS for CPC was 72.5% and 61.7%, respectively. For CPP and ACPP 5y OS was 100%. CONCLUSION: The present study is in agreement with the literature showing an excellent survival for CPP and ACPP but an inferior outcome for patients with CPC and TP53 mutation despite being assisted by a well-prepared multidisciplinary team with an adequate treatment.
MODL-06. Targeting c-MET in combination with radiation is effective in MET-fusion driven high-grade glioma
Authors: Zuckermann Marc , He Chen , Andrews Jared , Sloan-Henry Roketa , Bianski Brandon , Xie Jia , Wang Yingzhe , Twarog Nathaniel , Onar-Thomas Arzu , Ernst Kati , Yang Lei , Li Yong , Dalton James , Li Xiaoyu , Chepyala Divyabharathi , Zhu Xiaoyan , Zhang Junyuan , Xu Ke , Hover Laura , McKinnon Peter J , Pfister Stefan M , Rankovic Zoran , Freeman Burgess B , Shelat Anang A , Chiang Jason , Jones David T W , Tinkle Christopher L , Baker Suzanne J
Published: June 2022

Oncogenic fusion events involving c-MET have been observed in up to 12% of pediatric high-grade glioma (pHGG). MET inhibitors have displayed potent initial responses in MET rearranged tumors but acquired resistance to single agent modalities invariably occurs. To identify new treatment options against these tumors, we established two novel orthotopic mouse models including an immunocompetent, murine allograft and an intracranial patient-derived xenograft (PDX), both harboring distinct MET fusions. We analyzed the pharmacokinetic and pharmacodynamic profiles of two MET inhibitors, crizotinib and capmatinib, and examined their efficacy against tumor cell cultures derived from the aforementioned models. Capmatinib outperformed crizotinib in terms of specificity, potency and brain availability, resulting in a highly differential cellular response compared to crizotinib treatment. We evaluated the efficacy of both compounds in combination with radiotherapy (RT) and found that radiation further potentiated the inhibitory effect of capmatinib on tumor cell growth. We then utilized both models to assess the combinatorial effect of capmatinib and radiation on intracranial tumors in vivo and found that the combination therapy significantly increased overall survival in both cohorts. In the PDX model, the combination, relative to either intervention alone, induced a remarkable decrease of tumor burden, which persisted throughout the observation period in all treated animals. RNA-sequencing of capmatinib-treated tumors and tumor cell cultures revealed impaired expression of DNA repair genes. Further, we showed that capmatinib enhanced radiation-induced DNA damage, as demonstrated by increased γ-H2AX foci in treated cells, providing mechanistic insight for the cooperative effects of the combined treatment. Our results validate capmatinib as an effective inhibitor of MET in pHGG and demonstrate the outstanding efficacy of capmatinib and radiation against MET-driven pHGG in two complementary preclinical models, informing future clinical trials.
MODL-07. DNA methylation-based biobank of murine models for pediatric tumors
Authors: Zheng Tuyu , Sill Martin , Imle Roland , Shiraishi Ryo , Wang Wanchen , Morcavallo Alaide , Chesler Louis , Kawauchi Daisuke , Ayrault Olivier , Pavlo Lutsik , Pfister Stefan M , Kutscher Lena M , Banito Ana , Jones David W , Pajtler Kristian W , Zuckermann Marc
Published: June 2022

Recent advances in molecular profiling methods led to the identification of multiple new molecularly defined tumor types and subtypes, distinguished by distinct molecular markers and characteristic DNA methylation signatures. While the analysis of human methylome using microarrays has become an affordable and a routine in many labs, this technology until recently was not available for murine samples. In the past years, we have successfully generated a variety of mouse models for childhood tumors (e.g brain tumors and sarcomas) using different techniques, most of which faithfully reflect the human tumor counterparts at the histological level. With the recently released Infinium Mouse Methylation BeadChip, we now set out to use our models to generate the first DNA methylation database for murine pediatric tumors. We profiled more than 70 mouse models of pediatric tumors including gliomas, medulloblastomas, ependymomas and sarcomas, as well as 40 normal brain and muscle control tissues. We are currently performing a cross-species comparative analysis of established mouse models and the human counterparts. This will assess, how faithfully each models reflect the human situation and examine the effects of multiple passages of allografting. We will also analyze purified immune cell populations and use the derived methylation signatures to assess the model-specific immune microenvironment. Furthermore, we will investigate the methylomes of multiple putative cells-of-origin, which is hardly possible in the human context due to the lack of purified material. We will correlate these to murine tumor samples and thereby provide novel insights into tumor origins. In summary, our study will generate a validated biobank of murine models for pediatric cancers and provide a valuable resource for future developmental studies and preclinical trials.
MODL-12.Ex vivo model identifies druggable vulnerabilities in medulloblastoma
Authors: Gries Alexandre , Romanino Davide , Kumar Karthiga Santhana , Guerreiro Stücklin Ana S , Grotzer Michael A , Baumgartner Martin
Published: June 2022

Medulloblastoma (MB) is the most common malignant brain tumour in children and long-term sequelae in survivors caused by the harsh, non-targeted treatments is common. Current screening protocols for the detection of novel druggable vulnerabilities rely on 2D and 3D cell culture systems using established or primary tumour cells. However, these assays do neither provide the cellular, chemical and biophysical context of the tissue, nor reveal drug effects on the invasive behavior of the tumour cells. To overcome these limitations, we have established ex vivo Organotypic Cerebellum Slice Co-culture (OCSC) models for SHH and group 3 MB tumours, which provide spatio-temporal insights in the growth and dissemination behaviour of the tumour cells. OCSCs represent an excellent translational model for patient sample profiling, drug testing, and microenvironmental or explorative target identification studies in a physiologically relevant tissue context. We found that the AURKB inhibitor Barasertib (AZD-1152), which was ineffective to reduce ONS-76 cell invasion in vitro, effectively reduced tumour volume and proliferation of these SHH tumour cells in the tissue context. The AURKB inhibitor thus displays higher efficacy ex vivo, indicating an impact of the microenvironment on its functional activity. We further validated tumour suppressive activity of AURKB inhibition with Barasertib at low nanomolar concentration or with siRNA-mediated depletion of AURKB in Grp3 MB tumour cells and in primary tumour cells ex vivo, thereby confirming the therapeutic potential of AURKB inhibition against MB progression. We furthermore found that the combination of AURKB inhibition with irradiation or with the SRC inhibitor Dasatinib, lead to a near complete eradication of the tumour cells. Thus, OCSCs are a clinically relevant model where tumour material can be efficiently tested for drug sensitivities, which allowed us to identify AURKB inhibition as an effective treatment against tissue invasive MB.
MODL-18. Enhancing anti-CD47 mAb efficacy with radiotherapy for Group 3 paediatric medulloblastoma in preclinical models
Authors: Abbas Zahra , Buck Jessica , Ancliffe Mathew , Arias Clara Andradas , Howlett Meegan , Hii Hilary , Johns Terrance , Mitra Siddhartha , Gottardo Nicholas , Endersby Raelene
Published: June 2022

Medulloblastoma is the most common paediatric brain cancer. Standard treatment approaches, including craniospinal irradiation (CSI), can result in severe lifelong side effects and have not changed for decades resulting in a stagnation of survival outcomes for children with aggressive medulloblastoma. Despite successes in other cancers, no immunotherapies have been approved for use in paediatric medulloblastoma. Unlike other solid tumours, medulloblastomas are myeloid dominant, and immunotherapies must be rationally designed with the tumour microenvironment in mind. Anti-CD47 antibody therapy activates macrophages against cancer cells by blocking anti-phagocytic signalling mediated by CD47-SIRPa ligation and has shown preclinical efficacy in brain cancer models. We have developed preclinical CSI protocols that mimic clinical treatment response using a small animal radiotherapy platform. We show that CSI depletes adaptive immune cells in the brain, increasing the proportional abundance of myeloid cells, suggesting an opportunity to combine radiation with myeloid-targeted immunotherapy. We show that anti-CD47 therapy is ineffective as a single agent against a patient-derived xenograft model of Group 3 medulloblastoma (SJ_MB002), and that while the CSI protocol causes temporary tumour regression, the combination of anti-CD47 with CSI results in marked and persistent tumour regression. To enhance our preclinical evaluation of CSI and anti-CD47, we have developed new mouse models that more accurately reflect the developing microenvironment of children and show that immune populations in paediatric brain are distinct from adult mouse brain. Future work will elucidate the mechanisms by which radiotherapy alters the medulloblastoma microenvironment to enhance the anti-tumour activity of myeloid immune cells in the brain. By evaluating this novel combination of immunotherapy with standard medulloblastoma treatments, in age-appropriate models, our research should facilitate the rational selection and rapid translation of optimised treatment combinations for future medulloblastoma clinical trials.
MODL-22. Establishment of a novel system to specifically trace and ablate quiescent/slow cycling cells in high-grade glioma
Authors: Antonica Francesco , Santomaso Lucia , Pernici Davide , Petrucci Linda , Aiello Giuseppe , Cutarelli Alessandro , Conti Luciano , Romanel Alessandro , Miele Evelina , Tebaldi Toma , Tiberi Luca
Published: June 2022

Pediatric and adult high-grade gliomas are the most common malignant brain tumors, with poor prognosis due to recurrence and tumor infiltration after surgical removal and chemotherapy. Quiescent/slow cycling stem cells have been proposed to be one of the main players of tumor relapse but their involvement in in the infiltration remain unclear. Despite they have been described in mouse models or after transcriptional profiling of human tumor samples, their direct visualization, targeting and ablation remains a challenge. Here, we identified a population of malignant cells expressing Prominin-1 in a non-proliferating state in pediatric high-grade glioma patients. We next used a fluorescent cell cycle sensor to visualize quiescence tumor cells in mouse brain cancer and human cancer organoids. In particular, we characterized them within the tumor revealing the invasiveness capacity of slow cycling tumor cells. Furthermore, we generated a new system to specifically trace and ablate such cells. Indeed, lineage tracing experiments allowed to trace quiescent Prom1 progeny in the tumors after temozolomide treatment. In addition, the selective ablation of quiescent Prom1+ cells in mouse brain cancer reduced tumor infiltration and improved survival. Furthermore, time-lapse experiments showed that slow cycling cells are also able to infiltrate co-cultured human brain cancer organoids. Finally, using our new cancer organoid- and GBM spheroids-based models we identified a drug acting on quiescent cells leading to a reduction in cell invasion. Overall, our data show that quiescence/slow cycling cells are key driver of tumor invasiveness, the major malignant feature of high-grade brain cancer.
MODL-24. Focused ultrasound-mediated blood-brain barrier opening and panobinostat in a thalamic syngeneic murine DMG model is feasible and safe.
Authors: Webster Carrion Andrea , Wei Hong-Jian , McQuillan Nicholas , Tazhibi Masih , Kokossis Danae , Berg Xander , Minns Hanna , Zhang Xu , Zhang Zhiguo , Wang Junqiang , Fernandez Ester Calvo , Jan Chia-Ing , Padilla Oscar , Gartrell Robyn D , Becher Oren , Jr James H Garvin , Pavisic Jovana , Szalontay Luca , Konofagou Elisa E , Zacharoulis Stergios , Wu Cheng-Chia
Published: June 2022

Diffuse Midline Glioma with H3K27M mutation (DMG) is an aggressive unresectable central nervous system tumor of the brainstem, midline thalamus, or spine. Prognosis is poor and systemic agents have been ineffective partially due to limited permeability of the blood brain barrier (BBB). Non-invasive low intensity focused ultrasound (FUS) can be used for BBB opening (BBBO). Our preclinical studies showed safety and feasibility of targeting and BBBO in the brainstem; however, to our knowledge, FUS-guided BBBO for thalamic DMG has yet to be reported. RNA-seq was performed on mouse syngeneic DMG cells 4423 (PDGFB+, H3.3K27M, p53−/−) and results recapitulated molecular programs seen in human tumors. 4423 cells were injected into the thalamus of male B6 (Cg)-Tyrc-2J/J mice at 1.6mm lateral and 1.8mm posterior to the bregma at a depth of 3.2mm. MRI at 14-21 days post injection confirmed thalamic tumor growth. Histological analysis with Hematoxylin and Eosin stain was consistent with thalamic DMG. Tumor implantation rate was 85% and median survival was 38 days post injection. To test safety and feasibility of BBBO for thalamic tumors, a 1.5 MHz FUS transducer was used with concurrent microbubble injection. BBBO assessed by contrast-enhanced MRI. FUS achieved BBBO targeting the thalamic tumor without increased morbidity or mortality and BBB closure was observed on day 3 post-sonication. Next we tested the tolerance of drug delivery with panobinostat post-FUS at a dose of 20mg/kg weekly. The results are preliminary at this time; however, animals tolerated the combination therapy without morbidity or mortality. Preclinical models are crucial to improve the development of new therapeutic strategies. Establishing this syngeneic thalamic DMG murine model provides the opportunity to test FUS as a non-invasive drug delivery technology for thalamic DMG compared to brainstem DMG, and to re-visit therapeutic agents previously considered ineffective due to limited penetration of the BBB.
MODL-25. Radiation and focused ultrasound–mediated blood–brain barrier opening for DMG: safety and feasibility of combinatorial therapy
Authors: McQuillan Nicholas , Tazhibi Masih , Wei Hong-Jian , Pouliopoulos Antonios , Bendau Ethan , Carrion Andrea Webster , Berg Alexander , Kokossis Danae , Zhang Xu , Zhang Zhiguo , Englander Zachary , Yoh Nina , Jan Chia-Ing , Gartrell Robyn D , Garvin James , Szalontay Luca , Konofagou Elisa , Zacharoulis Stergios , Wu Cheng-Chia
Published: June 2022

Diffuse midline glioma (DMG) is a pediatric tumor with dismal prognosis. Systemic therapeutic strategies have been unsuccessful to date and radiotherapy (RT) remains the standard of care. A central impediment to systemic therapy is the blood-brain barrier (BBB), which precludes drug delivery to the tumor site. Focused ultrasound (FUS) with intravenous microbubbles can transiently and non-invasively circumvent the BBB to enhance drug delivery. Nevertheless, it remains unclear whether FUS is safe at the brainstem in combination with clinical doses of RT. In this study, we hypothesized that FUS-mediated BBB-opening (BBBO) is safe and feasible with 39 Gy RT. To establish a safety timeline, we administered FUS to the brainstem of nontumor bearing mice concurrent with or adjuvant to radiation; then, we validated our findings in a syngeneic orthotopic xenograft DMG model which received repeated sonication concurrent with RT. Male B6 (Cg)-Tyrc-2J/J albino mice received intracranial injection of 4423 mouse DMG cells (PDGFB+, H3.3K27M, p53−/−) at a location posterior and lateral to the lambda. A clinical RT dose of 39 Gy in 13 fractions was delivered to the brainstem with the Small Animal Radiation Research Platform (SARRP) or the XRAD-320 irradiator. FUS was administered with a 0.5 MHz transducer, and both BBBO and tumor volume were monitored with MRI. FUS-mediated BBBO in nontumor bearing mice receiving RT did not affect cardiorespiratory rate, motor function, and tissue integrity. Moreover, tumor bearing mice tolerated repeated brainstem BBBO concurrent with RT. 39 Gy over 13 fractions offered local control, although disease progression occurred in all animals approximately 3-4 weeks post-RT. Ultimately, repeated FUS-mediated BBB opening concurrent with RT is safe and feasible. In our brainstem DMG model, relapse occurs, making it ideal for future tests of combinatorial RT and FUS-mediated drug delivery.
MODL-28. Patient-derived, three-dimensional organoid platform for pediatric brain tumor modeling
Authors: Baubet Valerie , Beale David , Mariarita Santi , Viaene Angela , Madsen Peter , Jacob Fadi , Ming Guo-li , Hongjun Song , Phillip Storm , Koptyra Mateusz , Adam Resnick
Published: June 2022

Brain tumors have become the leading cause of cancer-related death in children. An important hurdle to scientific and clinical progress in the field has been the limited availability of preclinical tumor models. Historically, few pediatric brain tumor cell lines have been established and these often poorly recapitulate the phenotypes of the original tumors. In recent years, the Children’s Brain Tumor Network (CBTN) has accelerated the development of patient-derived cell lines and xenografts, offering these resources to the community through open-source access. While these models are extremely valuable, their development process can be lengthy and result in clonally selected lines which presents a challenge for studying complex tumor biology. To address the need for three-dimensional tissue culture, our group in conjunction with CBTN, utilized organoid culture from fresh tissue specimens obtained directly from surgical resection of various pediatric brain tumor histologies. This resulted in the development and banking of over 30 organoid models, which included ependymoma, high-grade glioma, medulloblastoma, atypical teratoid-rhabdoid tumor, diffuse midline glioma, and low-grade glioma diagnoses. Tissue was processed within an hour post extraction and cultured with universal media composition for each diagnosis. Organoid growth was observed within 2-3 weeks of initiation and continued for up to three months before banking. Banked organoids established growth upon return to culture. Phenotypic analysis revealed organoid cell composition that represented clinical histology. Importantly, organoids returned to culture post-banking demonstrated similar cell composition to those in the original culture, indicating their utility for subsequent preclinical testing. Here we provide a simple and efficient workflow for the generation and characterization of three-dimensional tumor organoids generated from fresh surgical pediatric brain tumor tissue. The platform has the potential to accelerate investigations into tumor biology and empower a diverse array of translational studies for the pediatric brain tumor field.
RONC-02. Clinical outcome after craniospinal irradiation with pencil beam scanning proton therapy for children and young adults/adolescents with brain tumors
Authors: Bachmann Nicolas , Vazquez Miriam , Bolsi Alessandra , Pachigolla Suvidya , De Angelis Claudio , Ahlhelm Frank , Lomax Antony , Pica Alessia , Weber Damien Charles
Published: June 2022

BACKGROUND: Craniospinal irradiation (CSI) is an essential treatment component to achieve cure for some brain tumors in children and young adults/adolescents (C-AYAs). Multimodal treatment approaches are however associated with treatment-related late toxicities in these developing patients. Pencil beam scanning proton therapy (PBSPT) allows for a minimization of dose delivered to organs at risk and the brain integral dose and, thus, potentially also a reduction of radiation-induced adverse events. We report the clinical outcome and toxicity rates after CSI for C-AYAs treated with PBSPT. METHODS: We reviewed 71 C-AYAs with a median age of 7.4 years (1.7 – 21.3) who received CSI with PBSPT. Medullobastoma (n=42, 59%) and ependymoma (n=8, 11%) were the most common histologies. Thirty-four (48%) patients presented with metastatic disease at diagnosis. Sixteen (23%) patients were treated for tumor recurrence/progression and 9 (13%) patients underwent re-irradiation. Median prescribed total dose was 54 GyRBE (18 – 60.4) and median craniospinal dose 24 GyRBE (18 – 36.8). Toxicities were recorded according to CTCAE v5.0. RESULTS: With a median follow-up time of 24 months (2 – 195), 12 (17%) patients died due to progressive disease. Eight (11%) patients experienced local failure and 15 (21%) distant failure after PBSPT. Estimated 2-year OS, LC and DC was 86.9%, 86.0% and 80.4%, respectively. Grade 3 acute toxicity (thrombocytopenia, neutropenia, nausea) was observed in 5 (7%) patients. Late grade 3 toxicities (stroke, cataract and CNS necrosis) were observed in 3 (4%) patients, 8, 9 and 16 months after PBSPT, respectively. One (1%) patient developed grade 4 CNS necrosis 8 months after CSI. Late grade ≥3 toxicity free rate was 92.3% at 2 years. No radiation-induced secondary cancer was observed. CONCLUSION: Excellent tumor and brain/spinal distant control and a low late grade ≥3 toxicity rate after CSI were observed in our cohort of C-AYAs treated with PBSPT.
RONC-04. Relationship between proton therapy and the development of the limbic system in pediatric posterior fossa tumors
Authors: Leenders Anne E M , de Robalo Bruno M Brito , Janssens Geert O R , Hoving Eelco W , Lequin Maarten H , Partanen Marita H
Published: June 2022

BACKGROUND: Pediatric brain tumor survivors may develop neuropsychological impairments after treatment. The first months after treatment could be a crucial time-window where the development of the brain may be affected by different types of treatments. For example, deficits in memory and learning related to hippocampal damage have resulted in radiotherapy dose constraints to the hippocampus. However, other limbic system substructures, important for cognition or behavior, may suffer from collateral doses. Therefore, we investigated the early effect of treatment on limbic structure volume. We hypothesized that radiotherapy (vs. no radiotherapy) would contribute to a decrease in volume of the limbic structures. METHODS AND MATERIALS: Thirty-eight patients with a tumor in the posterior fossa region (medulloblastoma n=12; pilocytic astrocytoma n=24; other=2) who were diagnosed between June 2018 and September 2020 and were alive ≥1 year diagnosis were included. Patients receiving neurosurgery only (n=26) were compared to patients treated with neurosurgery, proton therapy and chemotherapy (n=12). Limbic structures were automatically segmented in 111 MRI scans. These structures were amygdala, hippocampus (CA1+CA2/3), subiculum, dentate gyrus, parahippocampal gyrus, fornix, mammillary bodies, nucleus accumbens and thalamo-anteroventral nucleus of thalamus. RESULTS: Analyses revealed a significant negative effect of time on the amygdala (p<0.01), hippocampus (CA1) (p<0.001), and dentate gyrus (p<0.01). This indicates that these structures decreased in volume within the first year after diagnosis, independent of radiation treatment. Furthermore, an interaction effect was found between time and radiation in the subiculum (p=0.02) and fornix (p=0.052). CONCLUSION: These results indicate that the volumetric decline were stronger for the patients that received proton radiation. Future comparisons will test how results relate to the volumes in healthy children of the same age. Also, we will investigate whether this abnormal development is associated to the radiation dose and how it relates to the neuropsychological outcomes of the child over time.
RONC-07. Fractionated radiotherapy is required to accurately mimic neurostructural late effects in preclinical models
Authors: Whitehouse Jacqueline , Howlett Meegan , Buck Jessica , Somers Kale , Lawler Jessica , Hii Hilary , Carline Brooke , Kuchibhotla Mani , Sewoo Bhedita , Rosenow Tim , Feindel Kirk , Ebert Martin , Mehnert Andrew , Gottardo Nicholas , Endersby Raelene
Published: June 2022

Pediatric brain cancer patients treated with fractionated radiotherapy commonly develop long-term late side-effects including cognitive deficits. Many preclinical models of late effects have been developed that use a single, high dose of radiotherapy, which does not mimic the fractionated schedule children receive clinically. This study aimed to create a mouse model of late effects using clinically-relevant fractionated radiotherapy, and to measure the effects on the developing brain. Juvenile mice were treated at postnatal day 16 with a single dose of 8Gy whole brain radiation, or a mathematically-equivalent fractionated dose of 18Gy (9 x 2Gy daily fractions). Sham control mice received a CT scan, or 9 x sham CT scans. Mice were allowed to grow to young adulthood (63 days). Ex vivo anatomical MRI scans were performed along with diffusion tensor imaging (DTI) and histology. Mice receiving a single 8Gy radiation dose exhibited significantly decreased volumes in areas including the olfactory bulbs (-19%), hippocampus (-7%), corpus callosum (-9%) and motor cortex (-9%). In contrast, mice receiving fractionated radiotherapy showed fewer significantly decreased regions, although olfactory bulbs were reduced (-12%). Furthermore, doublecortin-positive cells were significantly reduced in the dentate gyrus indicating profound effects of radiotherapy on murine neural stem cells. Few radiotherapy-induced differences were observed by DTI, and immunohistochemistry revealed no changes in myelin basic protein, suggesting that white matter is minimally altered in mice. These results show that preclinical models exhibit treatment-induced late effects, and that commonly-used experimental approaches of single dose radiotherapy induce more neurological changes than an equivalent fractionated dose, thus may over-estimate radiotherapy-induced late effects. We have developed a clinically-relevant fractionated dosing protocol in mice, which replicates late effects experienced by children, and can be used to measure long-term effects of novel chemo/radiotherapy treatment combinations, ensuring children with brain cancer receive treatment both effective and safe treatment.
RONC-18 Radiosurgery for Primary and Metastatic CNS Malignancies in the Pediatric Population
Authors: Chen Katherine , Raleigh David , Sneed Penny , Fogh Shannon , Nakamura Jean , Boreta Lauren , Banerjee Anuradha , Mueller Sabine , Auguste Kurtis , Gupta Nalin , Braunstein Steve
Published: June 2022

PURPOSE: The purpose of this study is to describe outcomes after pediatric radiosurgery for malignant CNS lesions. METHODS: Retrospective chart review was performed for 31 pediatric patients treated at a single institution with Gamma Knife stereotactic radiosurgery (SRS) for primary or metastatic CNS malignancies between 2000-2020. RESULTS: 25 patients were treated with SRS for focal recurrences of primary CNS malignancies, 1 patient was treated in the adjuvant setting after initial resection, and 5 patients were treated for brain metastases. Primary CNS histologies included ependymoma (n=14), glioma (n=4), medulloblastoma (n=2), and meningioma (n=2). 65% were WHO grade 3 or 4. 71% of patients had received a prior course of involved-field external beam radiation to the brain to a median dose of 59.4 Gy in 33 fractions. Median age at SRS was 14 years (range 4-21). Radiosurgery was predominantly performed in a single fraction to a median dose of 17 Gy to a total of 42 targets among 29 patients. Two patients underwent fractionated radiosurgery to 30 Gy in 5 fractions for larger lesions. Median follow up after SRS was 44 months. 7 patients (23%) had no evidence of disease after SRS at a median follow up of 39 months. 6 patients (19%) developed local recurrence at the site of their treated lesion at a median of 13 months after SRS. 20 patients (65%) developed recurrent disease in the CNS outside of the radiosurgery field at a median of 11 months after SRS. 4 patients developed toxicity from SRS related to radiation treatment effect, all of which occurred within 1 year of SRS. CONCLUSIONS: SRS for malignant CNS lesions in the pediatric population provides effective local control and is well-tolerated. However, there remains a substantial risk of distant CNS failures given the nature of recurrent or metastatic disease in these patients.
SWK-01. Partnership between caregivers, patients and healthcare professionals: promoting collaboration in a complex care pathway in pediatric neuro-oncology
Authors: Granero Anita , Bertozzi Anne Isabelle , Baudou Eloise , Oliver Kathy
Published: June 2022

Children with a brain tumor and their families encounter, from the moment of diagnosis, a complex, multidisciplinary and multisite journey. Oscar's Angels (OA) is an association of trained patient advocate volunteers within a hospital structure who provide daily support to pediatric neuro-oncology patients and their families in complex care pathways. The association promotes collaboration in healthcare by facilitating a strong link between the daily reality of patients and their families and that of the hospital. OA volunteers are active and fully accepted members of the hospital multi-disciplinary team and collaborate on a very high level in the care of pediatric patients. Such a collaborative setting is possible because the work of OA is structured around three principles: Innovative, practical and theoretical initial and ongoing training and quality assessment of volunteers Patient and family support from Oscar’s Angels volunteers throughout the care pathway Government certification, institutional representation and active collaboration in educating healthcare professionals about the importance of patient advocacy and patients’ needs Operating in France since 2001 and in Italy since 2017 (with more than 600 and 200 families respectively supported last year), the OA volunteering program is specifically tailored to the needs and demands of hospitals and families. It can therefore be successfully reproduced in many settings. OA’s services come at no cost to hospitals. This is particularly important for implementing the program in developing countries where healthcare resources are extremely limited. But it is also relevant in developed countries as well where healthcare budgets are under strain. In 2020 an informal internal OA survey highlighted that the patient/family/volunteer/healthcare professional interface provides added value for all of these stakeholders. A formal survey will be conducted in 2022 to corroborate these results.
SWK-04. Investigation on Anxiety and Depression of Parents of Children with Central Nervous System Tumors
Authors: Yang Huajun , Zhang Yangqiong , Lai Mingyao , Li Juan , Cai Linbo
Published: June 2022

OBJECTIVE: Family members of children with Central Nervous System（CNS） tumors are often accompanied by anxiety, depression and other adverse emotions, which have a great impact on the quality of life of children. This study aims to investigate the incidence of anxiety and depression in parents of children with CNS tumors. METHODS: One of the parents of 165 children with CNS tumors who were hospitalized in Guangdong Sanjiu Brain Hospital from January 2021 to December 2021 were evaluated for anxiety and depression by SAS and SDS self-rating Depression Scale. The evaluation scores were compared with anxiety scores of normal Chinese population RESULTS: Our study cohort completed 165 questionnaires. Among them, 68 persons (41.21%, 68/165) had anxiety, and the anxiety score was (48.78±9.33), which was statistically significant compared with the normal Chinese population (29.78±10.01) (P < 0.01). 100 persons (60.61%, 100/165) had depression, and the depression score of the cohort was (55.02±9.98), higher than that of the normal population (33.46, 8.55), with statistical significance (P < 0.01). CONCLUSION: The parents of children with CNS tumor are the high risk group of anxiety and depression, which should arouse more clinical attention.
SWK-07. Family mental health screening early after a diagnosis of pediatric brain tumor
Authors: Rodemann Ashley , Hartmann Mary , Limbrick David , Abdelbaki Mohamed , Cluster Andrew
Published: June 2022

INTRODUCTION: A new diagnosis of a brain tumor in a child has significant emotional consequences for every member of the family. Nevertheless, early phases of oncologic care rarely provide formal mental health screening. METHODS: We implemented a mental health screening protocol for families and patients with a newly diagnosed brain tumor admitted to our pediatric intensive care unit (PICU) at the time of diagnosis. Screening instruments were selected based on their previous validation and relevance to both a brain tumor diagnosis and PICU admission. Parents were contacted by a member of our team within 2 weeks of their child’s diagnosis, and completed the screening independently within the next 2 weeks via an online interface. Parent proxy reports for the children were used when necessary. Scores were shared with the family and neuro-oncology team. When indicated, supportive counseling was offered. RESULTS: Eighteen patients have met criteria for mental health screening. Of these, 8 patient and parent dyads have completed the screening (mean patient age 8.6 years; 75% white; 50% female). Of the families that completed the evaluation, most parents (62.5%) reported that their child’s diagnosis negatively impacted their health-related quality of life (HRQL), while 87.5% of children themselves reported a lower HRQL. Most children (66.7%) self-reported having symptoms outside of normal range for anger, anxiety and depression and 100% had scores outside of normal range for pain interference with their daily lives. Only half of eligible families accepted referrals for new mental health support. CONCLUSION: Both children with a new diagnosis of brain tumor and their parents are at risk for impaired mental health and quality of life early after diagnosis. A systematic approach to these concerns at the time of diagnosis may be helpful.
TBIO-04. Comprehensive analysis of mutational signatures in pediatric cancers
Authors: Thatikonda Venu , Islam S M Ashiqul , Autry Robert J , Jones Barbara C , Gröbner Susanne , Warsow Gregor , Hutter Barbara , Huebschmann Daniel , Fröhling Stefan , Blattner-Johnson Mirjam , Jones David T W , Alexandrov Ludmil B , M, Pfister Stefan , Jäger Natalie
Published: June 2022

Analysis of mutational signatures can reveal the underlying molecular processes that have caused the somatic mutations found in genomes. We performed an extensive analysis encompassing mutational signatures of single base substitution and, for the first time, signatures of small insertions/deletions in ~800 whole-genome-sequenced tumor-normal pairs from 25 molecularly defined pediatric cancer types. More than half of this cohort consists of pediatric CNS-tumors (n=416), including high- and low-grade gliomas, ependymomas, and embryonal tumors. These were subsequently compared with COSMIC v.3 signatures to identify overlap with the latest set of known mutational signatures. We identified only a small number of mutational signatures active in pediatric cancers when compared to previously analyzed adult cancers. Amongst these, SBS1 and SBS5 were present in nearly all pediatric tumors analyzed, with a significant correlation of signature activity with age at diagnosis, as expected. Further, we found SBS21 activity in a fraction of high-grade gliomas, which is the result of defective DNA mismatch repair, SBS36 in fractions of ETMR and Group4-medulloblastoma, the result of defective base excision repair, and SBS44 in Group4-medulloblastomas, caused by defective DNA mismatch repair. For these signatures, no consistent genetic alteration was identified. We report a significantly smaller proportion of pediatric tumors which show homologous-recombination repair defect signature SBS3 compared to previously published analyses. Additionally, the previous mutational signature analysis of this cohort based on COSMIC v.2 reference signatures had identified a novel substitution signature (Signature.P1), active in the brain tumors ATRT and ependymoma. Our updated results suggest that Signature.P1 is not a pediatric specific mutational signature, but a treatment-associated signature identified in a small fraction of brain tumors that were annotated as treatment-naïve. This analysis provides a systematic overview of mutational signatures in pediatric cancers, which is relevant for understanding tumor biology and future research in defining biomarkers for treatment response.