bluuebunny/crossref_metadata_2025 huggingface dataset:
IMMU-03. DELETION OF RASA2 IN CAR T CELLS OVERCOMES DYSFUNCTIONAL IMMUNE SYNAPSE FORMATION AGAINST DIPGS, ENHANCING IN VITRO AND IN VIVO ANTITUMOR RESPONSE
Authors: Ibanez Jorge , Meehl Michaela , Ward Meghan B , Ocasio Jennifer , Baker Suzanne , Krenciute Giedre
Published: June 2024

BACKGROUND

Diffuse intrinsic pontine gliomas (DIPGs) are highly lethal pediatric brain tumors and a leading cause of cancer-related death in children. There is currently no cure for DIPG, highlighting an urgent need for novel therapeutics. Chimeric antigen receptor (CAR)-T-cell therapy offers great promise for DIPG treatment; however, several limitations need to be addressed. The goal of this study is to identify why CAR T cells are ineffective against DIPG and overcome this roadblock by improving the immune synapse (IS), or the interaction between tumor and CAR T cells.

METHODS

In this study, we targeted the tumor associated antigen B7-H3 by generating B7-H3 specific CAR T cells with CD28z signaling domain. We compared in vitro and in vivo antitumor response of CAR T cells against patient derived DIPGs and non-DIPG brain tumors. We contrasted the IS quality in DIPGs against other brain tumors by confocal microscopy. We further generated IS-enhanced CAR T cells by knocking out RASA2 and compared their performance against control KO in terms of IS-quality, killing kinetics, expansion, cytokine secretion, and in vivo tumor control.

RESULTS

Our data shows that CAR T cells have potent in vitro antitumor activity but fail in vivo against DIPGs which correlates with the formation of deficient IS, reflected by small synapses and poor calcium flux and cell polarity. RASA2 deletion in CAR T cells resulted in improved IS quality evidenced by bigger synapses, increased calcium flux, and CAR clustering upon antigen activation. In concordance, RASA2 KO CAR T cells elicited increased expansion, cytokine secretion, and in vivo antitumor activity against DIPGs compared to control KO.

CONCLUSIONS

This study shows that poor IS formation contributes to CAR T cell failure against DIPGs. Enhancing the IS formation in CAR T cells improves antitumor activity against DIPGs and should be considered for clinical translation.
IMMU-13. TUMOR INFLAMMATION-ASSOCIATED NEUROTOXICITY (TIAN): A TOXICITY SYNDROME IN PATIENTS TREATED WITH IMMUNOTHERAPY FOR CENTRAL NERVOUS SYSTEM TUMORS
Authors: Mahdi Jasia , Dietrich Jorg , Straathof Karin , Roddie Claire , Scott Brian J , Davidson Tom Belle , Prolo Laura , Batchelor Tracy T , Campen Cynthia J , Davis Kara L , Gust Juliane , Lim Michael , Majzner Robbie G , Park Julie R , Partap Sonia , Ramakrishna Sneha , Richards Rebecca , Schultz Liora , Vitanza Nicholas A , Wang Leo D , Mackall Crystal L , Monje Michelle
Published: June 2024

BACKGROUND

Immunotherapies are increasingly being explored as potential therapeutic modalities for the treatment of central nervous system (CNS) tumors and have unique toxicity profiles. Toxicity syndromes such as cytokine release syndrome (CRS) and immune effector-cell associated neurotoxicity (ICANS) were identified through experiences with chimeric antigen receptor (CAR) T-cell therapies for B cell malignancies; the creation of grading scales for these toxicities standardized the reporting and enabled management.

METHODS

From our collective experiences in treating patients with immunotherapies for CNS tumors, we have identified a localized neurotoxicity syndrome, distinct from the systemic toxicities of CRS and ICANS, termed tumor inflammation-associated neurotoxicity (TIAN).

RESULTS

TIAN develops secondary to localized inflammation at the tumor site. From a mechanistic perspective, we identified two types of TIAN: 1) type 1 TIAN arises in the setting of mechanical space constraints when peritumoral edema results in tissue shifts and increased intracranial pressure, which if untreated, can lead to a life-threatening herniation syndrome and 2) type 2 TIAN occurs when local neuronal dysfunction causes transient worsening/new neurological deficits. Whereas type 1 TIAN encompasses the concept of “pseudoprogression,” type 2 TIAN can occur in the absence of edema when neural-immune interactions disrupt local neural function. Patients can have both type 1 and type 2 TIAN simultaneously; understanding the type of TIAN can inform management. To facilitate the uniform reporting and management of TIAN, we created a TIAN grading scale that applies to both types of TIAN. Although, type 1 TIAN is generally associated with higher-grade toxicity, high-grade type 2 TIAN can occur when local inflammation compromises respiratory or autonomic functions.

CONCLUSIONS

Recognizing TIAN as a distinct, local neurotoxicity syndrome is critical to guiding clinical management and prognostication when treating patients with CNS tumors with immunotherapies.
LGG-16. BRAFV600K LOW-GRADE GLIOMA EMERGENCE DURING THERAPY FOR BRAFV600E HIGH-GRADE GLIOMA
Authors: Proctor Luke , Smith Amy , Aguilar-Bonilla Ana
Published: June 2024

BACKGROUND

BRAFV600E mutations are prevalent in pediatric brain tumors, constituting 20% of low-grade and 5% of high-grade gliomas. Other single-nucleotide substitutions in BRAF are described in adult cancers but rarely in pediatric brain tumors. Our case sheds light on a unique scenario—a patient with a BRAF-mutated high-grade spinal glioma who later developed slowly progressive intracranial low-grade glioma, subsequently undergoing rapid high-grade transformation.

METHODS

Case Report

RESULTS

Our patient initially presented as a thirteen-year-old male with a two-month history of progressive bilateral hand weakness/paresthesias. Spine MRI revealed a fusiform expansile intramedullary neoplasm from C3-T2, brain MRI was negative. Biopsy showed an anaplastic astrocytoma with BRAFV600E mutation and MYC-N amplification. Initial treatment included proton radiation and a 2-year course of Dabrafenib/Trametinib, maintaining disease stability. After four months off therapy, he developed local progression, and re-staging brain MRI showed new cerebellar/supratentorial lesions. Dabrafenib/Trametinib was re-started until progression two years later. He developed hydrocephalus and underwent ETV and brain tumor biopsy, which revealed a low-grade glioma with BRAFV600K mutation. At this point, Dabrafenib/Trametinib continued for another 1.5 years; he exhibited slow progression of the brain tumors before a cerebellar lesion developed rapid progression. He had GTR of the rapid-growing lesion, and pathology reported a Grade 4 invasive astrocytoma harboring BRAFV600E, two VUS MTOR mutations, and MGMT promoter methylation. Current treatment involves radiation therapy concurrent with temozolomide.

CONCLUSIONS

While combinatorial Dabrafenib/Trametinib is effective in glioma therapy, resistance and progression challenges persist. Our case presents a unique manifestation—a patient with a spinal high-grade glioma with BRAFV600E who developed a secondary low-grade glioma with BRAFV600K in the brain, which, after several years, transformed into a high-grade glioma. Future research is crucial for comprehending the intricate role of BRAF mutations in pediatric gliomas, paving the way for improved patient outcomes.
LGG-51. SYSTEMIC IMMUNE TOXICITY OF BRAF AND MEK-INHIBITORS IN CHILDREN: A PAN-CANADIAN SERIES
Authors: McKeown Tara , Renzi Samuele , Larouche Valerie , Yeung Rae , Hawkins Cynthia , Bartels Ute , Ramaswamy Vijay , Bouffet Eric , Tabori Uri , Bennett Julie , Das Anirban
Published: June 2024

BACKGROUND

BRAF/MEK-inhibitors have been transformative for pediatric gliomas with RAS/MAPK pathway aberrations. The RAS/MAPK pathway has a complex role in immune regulation. Though well-known in adults, the systemic immune-related adverse effects (irAE) of BRAF/MEKi in children are not widely reported.

METHODS

We performed a retrospective chart review for irAE following BRAF/MEKi in children treated at SickKids between 2016-2023. Additional patients were included through a pan-Canadian survey.

RESULTS

136 patients on BRAF/MEKi were included (MEKi: 74%, BRAFi: 13%, BRAF+MEKi: 13%); irAE was reported in 6/136 (4.5%). One additional patient was included through the national survey. Median age was 14 years (range: 7-16). Male:female was 3:4. Three patients were on BRAFi, and two each on MEKi, and BRAF+MEKi. Early events developing within weeks of drug initiation included hyper-immune systemic inflammatory responses in three children on BRAFi and one child on MEKi. There was no evidence of any concomitant infection. Two children needed intensive care and showed evidence of multi-organ dysfunction. Delayed irAE developing after months to years on therapy included multi-systemic sarcoid-like reaction, parasympathetic dysautonomia (both on BRAF+MEKi) and brachial neuritis/Parsonage-Turner syndrome (MEKi). Management included drug holidays, dose reductions, and immunosuppressive treatment with steroids. Long-term steroids were needed in two of these seven patients.

CONCLUSIONS

Pediatric oncologists need to be aware of rare yet possibly under-reported systemic immune toxicity in children treated with BRAF/MEKi. They can present acutely, or while on chronic therapy. Management may be challenging in view of issues with rebound tumor growth on stopping some of these drugs, with select patients needing concomitant, long-term immunosuppressive therapy. Genetic susceptibility and biomarkers may need to be systematically studied in future clinical trials of novel RAS/MAPK inhibitors. Continued surveillance and reporting are needed for the marketed compounds, especially for children on long-term use of these inhibitors.
LGG-55. DIFFERENTIAL TOXICITY PROFILE OF INDIVIDUAL MEK INHIBITORS: A MULTI-INSTITUTION RETROSPECTIVE REVIEW
Authors: Shin Jimin , Zhang Anthony , Meyer Ashley , Ogle Andrea , Shatara Margaret , Cluster Andrew , Abdelbaki Mohamed S , Navalkele Pournima , Faigenbaum Erica , Brosius Stephanie , Kotch Chelsea , Cantor Evan , Brossier Nicole
Published: June 2024

BACKGROUND

Most pediatric low-grade gliomas (pLGGs) are driven by molecular aberrations in the mitogen-activated protein kinase pathway (MAPK), which can be targeted by novel agents such as MEK inhibitors (MEKi.) However, MEKi use is accompanied by a varied side effect profile, with the most severe dose-limiting effects involving dermatologic, cardiac, and ophthalmic toxicities.

METHODS

Multi-institutional retrospective chart review of patients less than 25 years of age who underwent MEKi monotherapy between 2015-2022 was conducted. Data was collected from 4 sites, including Connecticut Children’s, St. Louis Children’s Hospital, Cardinal Glennon Children’s Hospital, and Children’s Hospital of Philadelphia.

RESULTS

Ninety-six patients were included in the analysis; 54 (56.4%) with brain tumors and 56 (58.3%) with germline mutation in NF-1. Forty-nine (51%) received trametinib, 42 (43.8%) selumetinib, 5 (5%) binimetinib. Of 42 patients with skin toxicity data available, 35 (83%) had cutaneous toxicity, with the most prevalent being acneiform rash (40.0%), followed by maculopapular rash (28.6%) and eczematous dermatitis (11.4%). The mean number of cutaneous skin toxicities was 2.4 (trametinib group = 2.2, selumetinib group = 2.6). Eighteen of 96 (18.8%) patients experienced cardiac toxicity, of which 11 (61.1%), experienced reduction in left ventricular ejection fraction (6 trametinib, 5 selumetinib), 4 (22.2%) developed pericardial effusions. 10 of 96 (10.4%) patients experienced ophthalmic toxicities, most commonly blurred vision (30.0%). Other toxicities included elevated CK (36, 37.5%), anemia (32, 33.3%), and eosinophilia (17, 17.7%).

CONCLUSION

There was not an observable clinically relevant difference in toxicities between MEKi, with skin toxicity the most prevalent. The prevalence of cardiac toxicity in the patient cohort reinforces the need for appropriate monitoring via echocardiography. MEKi remain an excellent option for therapy for LGG but with the need for continued supportive care and monitoring.
MDB-26. GENE REGULATORY NETWORK LANDSCAPE OF GROUP 3/4 MEDULLOBLASTOMA
Authors: Joshi Piyush , Stelzer Tamina , Okonechnikov Konstantin , Sarropoulos Ioannis , Sepp Mari , Pour-Jamnani Mischan V , Rademacher Anne , Yamada-Saito Tetsuya , Schneider Céline , Schmidt Julia , Schäfer Philipp , Leiss Kevin , Bortolomeazzi Michele , Mallm Jan-Philipp , da Silva Patricia B G , Statz Britta , Wittmann Andrea , Schramm Kathrin , Blattner-Johnson Mirjam , Fiesel Petra , Jones Barbara , Milde Till , Pajtler Kristian , van Tilburg Cornelis M , Witt Olaf , Rippe Karsten , Korshunov Andrey , Jones David T W , Hovestadt Volker , Northcott Paul A , Thongjuea Supat , Jäger Natalie , Kaessmann Henrik , Pfister Stefan M , Kutscher Lena M
Published: June 2024

Intra-tumor heterogeneity in brain cancers contributes to therapy resistance and relapse through positive selection of resistant tumor cell populations. Resolving the molecular mechanisms driving intra-tumor heterogeneity will uncover tumor-specific vulnerabilities and advance effective treatment strategies. Group 3/4 medulloblastomas, the most common embryonal cerebellar tumor subgroup, are highly heterogeneous tumors with high frequency of relapse which are almost certainly fatal. Here, we generated and analyzed a comprehensive single-cell multi-omic Group 3/4 medulloblastoma atlas, comprising 355,295 cells from 38 tumor patients representing eight Group 3/4 molecular subtypes. We identified transcription factor gene regulatory networks driving intra- and inter-tumor heterogeneity in Group 3/4 medulloblastoma, and determined the common regulatory framework that drives this heterogeneity. We show that Group 3/4 tumor diversity stems from differential enrichment of cell-states along four molecular identity axes: photoreceptor, MYC, precursor, and unipolar brush cell-like. Further, we show that intermediate subtype I/VII tumors exhibit a unique biology where a tumor exhibits dual Group 3 and Group 4-like tumor cell-states in a single tumor, and for a subset of these tumors, we identified a potential role of PAX6 in driving the observed dual trajectory. Altogether, our study demonstrates how oncogenic events together with key lineage determinants hijack normal developmental programs and drive Group 3/4 tumor identity away from the normal cerebellar unipolar brush cell-lineage.
MDB-35. DEVELOPMENT OF DUAL LUCIFERASE ASSAY FOR 3D-COMPATIBLE HIGH THROUGHPUT SCREENING IN MEDULLOBLASTOMA
Authors: Ajongbolo Aderonke O , Sperle Karen , Zheng Haozhe , Pochan Darrin J , Langhans Sigrid A
Published: June 2024

BACKGROUND

Medulloblastoma is the most common malignant pediatric brain tumor, originating from the cerebellum, a part of the brain that controls balance, coordinated movement and other non-motor behaviors. 2D cell cultures are commonly used for testing of new compounds in high throughput screening (HTS) targeting this cancer, largely because there are numerous highly optimized assays available for analyzing this cell culture model. However, they have significant limitation in mimicking in vivo conditions of the tumor microenvironment. 3D cell-culture methods have been embraced to enhance the modeling of in vivo tissue, replicating the multicellular architecture and the characteristics of the extracellular matrix. Presently, there are efforts to integrate 3D cell-culture with HTS to yield more clinically relevant results. However, one of the requirements for this is a 3D-compatible cell-based assay suitable for HTS. We developed such an assay which measures the activity of YAP/TAZ, a central molecule of Hippo-signaling pathway, and has been implicated in medulloblastoma. It plays a crucial role in maintaining tissue balance by coordinating proliferation, apoptosis, and differentiation.

METHODS

We cloned 8xGTIIC-NlucP, a brighter and more sensitive luciferase (Nanoluciferase) reporter plasmid that detects YAP/TAZ activity. Responsiveness to YAP/TAZ activity, and its inhibition were detected using a dual luciferase assay in the medulloblastoma cell lines after transfection. A normalization plasmid with a constitutive promoter for firefly luciferase was used in this assay to differentiate compounds that affect YAP/TAZ activity specifically as opposed to those that are toxic to the cells.

RESULTS

A robust signal for YAP/TAZ activity, and its reduction when cells were treated with inhibitor, was seen in the three medulloblastoma cell lines used, which further validates the result.

CONCLUSION

In conclusion, we were able to develop a 3D-compatible cell-based assay with Nanoluciferase which can be a foundation for HTS targeting medulloblastoma using 3D cultures.
MDB-39. HOW DO TUMOUR DERIVED EXTRACELLULAR VESICLES INTERACT WITH THE DEVELOPING NERVOUS SYSTEM AND LEAD TO ALTERED PAIN PROCESSING IN CANCER SURVIVORS?
Authors: Jackson Hannah K , Grabowska Anna , James Victoria , Dajas-Bailador Federico , Coyle Beth , Hathway Gareth
Published: June 2024

BACKGROUND

Childhood cancer-related pain and its treatment lack sufficient clinical attention due to limited understanding of the underlying mechanisms. While chemotherapy-induced peripheral neuropathic pain (CIPN) mechanisms in adults have been extensively studied, those in early life remain unexplored. In the CIPN literature there is a growing body of evidence for tumour derived factors altering pain processing. Our study aims to understand how tumour derived extracellular vesicles (EVs) interact with the developing nervous system and impact pain processing in childhood brain tumour survivors.

METHODS

We determined dose-response curves and IC50 values for several medulloblastoma (MB) cell lines using standard-of-care chemotherapy drugs: vincristine, etoposide, cisplatin, and lomustine. EVs were isolated via size exclusion chromatography and characterised through western blotting, flow cytometry and electron microscopy. We quantified the effects of chemotherapy on EV release using ZetaView analysis. We then tested whether EVs from relevant MB cell lines could influence axon development in primary mouse embryonic day 16.5 dorsal root ganglion (DRG) neurons in vitro after pre-treatment with chemotherapy-treated EVs.

RESULTS

EVs from chemotherapy-treated and untreated cells exhibited similar size and shape. However, a combination of vincristine, etoposide, and cisplatin at low concentrations significantly increased EV secretion by MB cell lines. Moreover, 24-hours following treatment with chemotherapeutic exposed EVs there was complete cell death of embryonic DRG neurons compared to the PBS or control EV treated neurons.

CONCLUSION

Standard chemotherapy drugs substantially enhanced EV release from MB cells, and co-culture of embryonic DRG neurons with chemotherapy exposed EVs resulted in neuronal death. Our next step is to investigate whether administering these selected EVs in healthy animals alters pain responses and pain maturation. We also aim to study the biodistribution of these EVs within the nervous system and body, after infusion into the cerebrospinal fluid as well as how EV cargo is altered by chemotherapeutics.
MDB-43. SHARED DECISION-MAKING (SDM) REGARDING RADIATION-AVOIDING (RA) THERAPY IN YOUNG CHILDREN WITH MEDULLOBLASTOMA (MB)
Authors: Kugelmann Andrew R , Gross Naina L , Srinivasan Anand , McNall-Knapp Rene Y
Published: June 2024

BACKGROUND

Standard treatment for MB in patients age ≥ 3 years includes craniospinal radiation with tumor bed boost and chemotherapy. Radiation carries substantial risk of long-term issues, particularly in the youngest patients: second malignancy, neurocognitive issues, vasculopathy and endocrinopathies. Numerous trials have attempted to decrease or avoid the use of radiation by intensifying chemotherapy, some using high dose chemotherapy with autologous hematopoietic stem cell rescue (HDC). One of the most successful RA protocols, Children’s Oncology Group ACNS0334 enrolled children age < 36 months and treated with 3 cycles of induction (+/- high dose methotrexate) and 3 cycles HDC without planned radiation. Since 2012, we offer SDM with caregivers regarding treatment of their children ages 3-7 years with MB. Caregivers may choose standard radiation and chemotherapy (SRC) or the RA treatment above.

OBJECTIVE

Describe patient and disease characteristics and outcomes in patients aged 3-7 years treated for MB with SDM regarding the use of radiation.

METHODS

Retrospective analysis of diagnosis, treatment and clinical outcomes in all children <8 y.o. who completed treatment for MB between 2012 and 2023.

RESULTS

There were 16 patients offered SDM (all gross total resection without metastases) 7 chose RA and 9 SRC. The SRC group was enriched with molecularly high-risk patients (4 MYC or MYCN amplification, 1 SHH with P53 mutation). In the RA group, relapse occurred in 14% (n=1 of 7). In the SRC group, 44% relapsed (n=4 of 9). One patient developed high-grade glioma in the radiation boost field 10 years later. There was 1 death in the RA group due to disease progression and 5 deaths in the SRC group, 1 due to second malignancy.

CONCLUSIONS

We report excellent survival with RA therapy for appropriately selected young children (age 3-7 years) when SDM is used with families to determine the best treatment for their child.
MDB-47. DEEP LEARNING DECODES NEW SITES OF RNA TRANSLATION IN MEDULLOBLASTOMA
Authors: Clauwaert Jim , Menschaert Gerben , Prensner John
Published: June 2024

BACKGROUND

Medulloblastoma, a malignant brain cancer predominantly affecting children, possesses a high propensity for metastasis and is frequently fatal. Through studies on RNA translation, a core biological process, we aim to uncover the disease biology of cancer in order to design therapeutic targets. Yet, the exploration of canonical protein-coding genes has thus far yielded few viable targets in medulloblastoma, where non-canonical open reading frames (ORFs) are increasingly being investigated for their regulatory role.

METHODS

To address the significant challenge in delineating novel translated ORFs in individual cells or tissues, we have designed RIBO-former, a best-of-its-class machine learning model that leverages ribosome profiling data to detect translated open reading frames. Through RIBO-former, we expanded the proteome of healthy prenatal (n=30) and adult (n=42) samples, which are notoriously hard to process due to low read depth and noise, in addition to medulloblastoma cancer tissue (n=8) and cell line (n=15) data.

RESULTS

Across all medulloblastoma cell lines, we determine an initial selection of 3,638 non-canonical ORFs. Unsupervised clustering of the ribosome profiling read counts within these non-canonical ORF regions group samples according to the described subtypes of medulloblastoma cancer, hinting at the significant role these ncORFs play in protein homeostasis. Looking into distinct expression profiles between cell lines with high and low MYC expression, we revealed 201 non-canonical ORFs that are differentially expressed. We evaluate our data through various analyses including testing of which ORFs have a viable sequence context for translation, achieved through another in-house tool (TIS Transformer).

CONCLUSIONS

By taking advantage of advances in machine learning, we were able to uncover new sites of translation in medulloblastoma that can aid the future discovery of therapeutic targets. As such, we were able to find 22 highly promising non-canonical ORFs that show unique expression profiles in relation to MYC in medulloblastoma.
MDB-50. CAR-T CELL-DERIVED EXOSOMES LOADED WITH THERAPEUTIC SIRNA IS A PROMISING TECHNIQUE IN THE TREATMENT OF SUBGROUP 3 MEDULLOBLASTOMA
Authors: Alahdal Murad , Perera Ranjan J
Published: June 2024

Medulloblastoma (MB) is a childhood life-threatening tumor that occurs in the cerebellum. This tumor showed resistance against several types of immunotherapies like anti-PD1, cancer vaccines, monoclonal antibodies (mAbs), and even CAR-T cells. Subgroup 3 MB is the worst threatening subtype that poorly responds to treatment. Interestingly, our data showed that the HLX gene a transcription factor that regulates cell growth is highly expressed in G3-MB and associated with poor prognosis. The siRNA-HLX inhibited tumor growth in vitro and in vivo and promisingly showed long survival in the immunocompetent mouse model. We developed CAR-T-Exosomes that can pass brain-blood barriers (BBB) and deliver therapeutic siRNA to the brain tumor. Further analysis revealed that CAR-T-Exosomes contain T cell cytotoxicity materials that can destroy tumor cells and induce anti-tumor immune response. Promisingly, the expression of HLX was significantly inhibited in the tumor cells and the anti-tumor immune response was enhanced. CAR-T-Exosomes have high safety and can induce anti-tumor response without stimulation of immunotoxicity side effects like cytokine release syndrome (CRS). In this study, we are highlighting anti-EPHA2-CAR-Exosomes as a highly specific type of tumor CAR-T-Exos immunotherapy due to a very low expression of EPHA2 in normal cells and overexpression in medulloblastoma, particularly G3-MB. Therefore, we speculate significant inhibition of tumor growth and activation of CTL effector cells in the tumor microenvironment. This study provides a new biological technique for delivering tumor suppressor RNAs and developing specific anti-tumor immune responses. Indeed, the promising safety of anti-EPHA2-CAR-T cell exosomes compared to cell-based immunotherapy.
MDB-51. PHASE II INTERVENTIONAL STUDY TO EVALUATE THE SAFETY AND EFFICACY OF STANDARD AND HIGH-DOSE CHEMOTHERAPY COMBINED WITH CRANIOSPINAL IRRADIATION WITH PROTON THERAPY IN PATIENTS WITH METASTATIC MEDULLOBLASTOMA AND OTHER EMBRYONIC CANCERS: PRELIMINARY RESULTS
Authors: Guidi Milena , Fonte Carla , Tellini Marco , Censullo Marialuigia , Castelli Barbara , Gori Carlotta Gemma , Giunti Laura , Nicola Marco Di , Buccoliero Anna Maria , Caporalini Chiara , Giordano Flavio , Rombi Barbara , Desideri Isacco , Pugi Alessandra , Tortora Katia , Greto Daniela , Genitori Lorenzo , Leo Maria Carmela , Sardi Iacopo
Published: June 2024

BACKGROUND

The high risk medulloblastoma remains a leading cause of cancer-related death in children.

METHODS

A total of 18 patients have been enrolled from February 2018 to May 2022.The median age was 7,5 years (range; 12 males and 6 female). The protocol predicted the first phase of induction with 4 cycles of chemotherapy. After induction patients with favorable histology without evidence of disease were enrolled to proton therapy (with concomitant vinorelbine biweekly). The maintenance phase with Lomustine repeated every 9 weeks and vinorelbine every 3 weeks for overall 12-18 months (PR). Conversely LC/A MB, were subjected to consolidation phase with high dose of chemotherapy with tiothepa followed by autologous HSC transplant and successive maintenance phase of 6 months.

RESULTS

At October 2023, the median follow up was 24 months. After the induction phase 14 patients showed CR, 2 PR, 1PD, 1SD. At subsequent re-evaluations two with PR, showed disease control, one CR and the other SD and the patient with PD showed CR. Patient with SD showed an unchanged state of the disease. During the reporting period two patient died for progression of the underlying disease. At 24 months from the start of treatment the PFS was 75,4 % (95% CI: 34.1% - 87.6%) and at 15 months the OS was 86,1% (95% CI: 68.1% - 99.2%). The principal expected side effects of chemotherapy were hematology toxicity and 58% rate of GH deficiency. Among the unexpected side effect was CMV retinopathy with complete blindness and leukoencephalopathy after high dose of thiotepa and proton irradiation. We reported only one case of ototoxicity.

CONCLUSIONS

The use of proton therapy combined with intensive chemotherapy and myeloablative chemotherapy only in selected cases and always before irradiation has proven feasible and effective in the treatment of high-risk patients medulloblastomas and other embryonic tumors.
MDB-59. INTEGRATIVE PROTEO-GENOMICS TO DECIPHER MOLECULAR MECHANISMS UNDERLYING SUBGROUP-SPECIFIC HETEROGENEITY IN MEDULLOBLASTOMA
Authors: Li Yiran , Gudenas Brian L , Smith Kyle S , Lin Hong , North Kelsey C , Soliman Taha , Hadley Jennifer , Batts Melissa , Dhanda Sandeep K , Atkinson Natasha , Mercer Kimberly S , High Anthony , Yuan Zuo-Fei , Wang Xusheng , Peng Junmin , Roussel Martine F , Robinson Giles W , Orr Brent A , Northcott Paul A
Published: June 2024

BACKGROUND

Medulloblastoma (MB), an aggressive pediatric brain cancer, poses significant treatment challenges due to its complex disease biology, comprising a collection of discrete molecular subtypes that require different treatment. Although the genomics, transcriptomics, and epigenetic landscapes of biologically distinct MB subgroups are well-annotated and have contributed to enhanced diagnostics and risk stratification, the intersection of these molecular layers with the MB proteome remains poorly defined

METHODS

To overcome this knowledge gap, we sought to create a deep proteomics and phospho-proteomics cohort from a large MB clinical trial cohort (SJMB12), comprising 166 primary patient tumors, complemented with matched DNA methylation, whole-exome sequencing (WES), and RNA sequencing (RNA-seq) datasets. Proteomics data were interrogated using unsupervised computational techniques and evaluated for pathway enrichment and kinase activity. To complement these bulk tumor datasets, we investigated the tumor microenvironment focusing on immune and glial cell populations, using single-nuclei RNA and ATAC sequencing (snRNA-seq and snATAC-seq) for validation

RESULTS

Distinct proteomics subgroups were identified, correlating with established MB clinical subgroups and unveiling previously unrecognized proteomics subgroups. The integration of proteomics with mutational data revealed downstream effects of genetic alterations not evident in the transcriptome, implicating novel molecular mechanisms contributing to disease pathogenesis. Protein-protein interaction networks discovered novel signaling hubs and pathways, highlighting the power of proteomics to detect subgroup-specific drivers of disease that may represent attractive therapeutic vulnerabilities

CONCLUSIONS

Our multi-omics approach applied to a large series of primary MB patient tumors revealed novel mechanisms underlying MB subgroup biology that were previously hidden at the genetic, epigenetic, and transcriptional level. These findings offer a comprehensive, systems biology view of MB pathogenesis, fostering provocative insights that serve as a foundation for future discovery and the development of more effective personalized treatment strategies.
MDB-83. OUTCOMES OF INFANTS AND YOUNG CHILDREN WITH NEWLY DIAGNOSED SHH MEDULLOBLASTOMA TREATED ON THE NEXT CONSORTIUM “HEAD START” 4 PROTOCOL
Authors: Dhall Girish , Stanek Joseph , Blue Megan , Patel Parth , Thomas Diana , Pierson CHristopher , Tamrazi Benita , Mahadeo Kris , Fleming Jessica , Bell Erica , MIller Katherine , Grischow Olivia , Liszkay Thomas , Owen Scott , Hastings Caroline , Tsui Karen , Mazewski Claire , Friedman Gregory , Moertel Christopher , Hanson Derek , Koschman Carl , Brock Guy , Asgharzadeh Shahab , Chakravarti Arnab , Wong Kenneth , Nelson Marvin , Boue Daniel , Biegel Jaclyn , Mardis Elaine , Finlay Jonathan
Published: June 2024

BACKGROUND

Infants and young children with SHH medulloblastoma were demonstrated to have a favorable outcome on “Head Start (HS)” III clinical trial utilizing five cycles of induction followed by one myeloablative high-dose chemotherapy (HDCT) cycle. We present the results of “Head Start” 4 (HS-4) trial where SHH subgroup patients received either three or five cycles of induction based on response followed by one HDCT cycle (similar to HS III).

METHODS

Eligibility included children <6 years of age at diagnosis of localized medulloblastoma and <10 years for patients with disseminated disease. Eligible patients with SHH medulloblastoma were considered “low-risk” and non-randomly assigned to receive three cycles (five cycles if <complete response) of induction chemotherapy (vincristine, cisplatin, cyclophosphamide, etoposide, and high-dose methotrexate) followed by consolidation with single HDCT cycle (thiotepa, carboplatin, etoposide) and autologous hematopoietic stem-cell rescue.

RESULTS

Thirty-nine children with SHH medulloblastoma were enrolled on HS-4 with median age of 2.18 years (range: 0.28-6.88 years). Median follow-up for this cohort is 41 months (range: 18-67 months). Patients with localized SHH medulloblastoma (n=28) had significantly better 3-year event-free (EFS) compared to disseminated patients (n=11): 96.4% (95% CI: 90-100%) and 36.4% (95% CI: 16.6-79.5%), respectively (p<0.0001); however, there was no significant difference in 3-year overall survival (OS) between the two groups: 100% and 90.0% (95% CI: 73.2-100%), respectively (p=0.10). The estimated 3-year EFS for localized SHH subtype 1 and 2 patients was 100% and 95%, respectively (p=0.63). None of trial patients received irradiation prior to progression. All patients, except for four, underwent three cycles of induction. Germline variants were detected in 27% of patients tested (8/30).

CONCLUSION

We report excellent results for young children with localized SHH medulloblastoma when treated with only three cycles (reduced) of induction and single HDCT cycle on HS-4 trial without irradiation. Molecular data will be presented.
MDB-97. INVESTIGATING THE IMMUNOMODULATORY ROLE OF V-DOMAIN IG SUPPRESSOR OF T-CELL ACTIVATION IN AN AGGRESSIVE MURINE MODEL OF PEDIATRIC MEDULLOBLASTOMA
Authors: Perez Natalia Andrea Munoz , Pensabene Juliana , Moziak Kirsten , Yazejian Rita , Zang Xingxing , Loeb David M , Martin Allison M
Published: June 2024

BACKGROUND

Efforts to treat relapsed medulloblastoma patients with immune checkpoint inhibitors aim to enhance T-cell recognition and elimination of tumor cells. However, significant barriers to treatment efficacy include low numbers of infiltrating effector T-cells and paucity of PD-L1 expression in the tumor microenvironment. Thus, identifying alternative immune checkpoints on the predominant immune cells that infiltrate tumors represents an attractive therapeutic alternative.

METHODS

Medulloblastoma tumor cells (mCB MYC DNp53) are orthotopically implanted into the right cerebellum of C57/BL6J mice. Once moribund, tumors are harvested and analyzed by flow cytometry. For in vitro studies, tumor cells are co-cultured at increasing concentrations with naïve splenic CD4+ T-cells, CD3/CD28 beads, and rIL-2 for 5 days and then analyzed by flow cytometry.

RESULTS

Flow cytometric analysis of tumors reveals an abundance of CD45highCD11bhigh tumor-associated macrophages (TAMs), CD45intCD11bint tumor-associated microglia, and CD4+FoxP3+Treg cells. Across all three immune populations, we observe high expression of the inhibitory immune checkpoint, V-domain Ig Suppressor of T-cell Activation (VISTA), with the highest MFI observed on Mø-like TAMs (n=9 tumors; p<0.05). Compared to sham controls, infiltration of Mø-like TAMs is specific to the tumor and express higher levels of MHCII than Mg-like cells (n=14 tumors, 6 sham; p <0.05). Additionally, we find that medulloblastoma tumor cells (mCB MYC DNp53) express VISTA’s binding partner, VSIG3. Tumor cells co-cultured with CD4+ T-cells can inhibit T-cell proliferation in vitro. Preliminary results suggest that addition of 2ug/mL of anti-VISTA blocking antibody (13F3) can rescue proliferation.

CONCLUSIONS

Tumors are highly infiltrated by VISTA+ T-regs and TAMs. These TAMs upregulate MHCII, suggesting that they are presenting antigen in the context of an inhibitory molecule. Furthermore, our in vitro results warrant further investigation into the role of the VISTA/VSIG3 axis in inhibiting T-cells and supports blocking VISTA as a potential strategy to promote T-cell activation and an anti-tumor response.
MDB-98. HISTOPATHOLOGY IS A ROBUST TOOL TO DIFFERENTIATE BETWEEN SHH AND WNT MEDULLOBLASTOMA VERSUS NON-SHH/NON-WNT MEDULLOBLASTOMA: COMPARATIVE ANALYSIS OF HISTOPATHOLOGY, CHROMOSOMAL MICROARRAY, NANOSTRING BASED 22-GENE ASSAY, AND DNA METHYLATION FOR MEDULLOBLASTOMA SUBGROUP ASSIGNMENT ON “HEAD START” 4 CLINICAL TRIAL
Authors: Littrell Mary Elizabeth , Patel Parth , Blue Megan , Biegel Jaclyn , Almira-Suarez Isabel , Hwang Eugene , Miller Katherine , Thomas Diana , Pierson Christopher , Boue Daniel , Mardis Elaine , Finlay Jonathan , Dhall Girish
Published: June 2024

BACKGROUND

“Head Start-4” (HS-4) is a prospective, randomized clinic trial that tailors treatment based on medulloblastoma molecular subgroups (WNT, SHH, Group 3, and Group 4) and response to induction chemotherapy, and compares the efficacy of one versus three (tandem) cycles of myeloablative therapy. Here we compare different methodologies used to distinguish between WNT/SHH medulloblastoma (low-risk arm) and non-SHH/non-WNT medulloblastoma (high-risk arm) during the course of the trial.

METHODS

When HS-4 trial began enrolling patients in 2015, in the absence of a CAP-CLIA certified test for methylation and gene expression profile, we utilized histopathology/immunochemistry (HP/IHC) and chromosomal microarray (CMA) via OncoScanTM (Thermo Fisher) to classify medulloblastoma samples into either WNT, SHH, or non-WNT/non-SHH (Subgroups 3 and 4) at the time of diagnosis. Retrospectively, we performed both NanoString based 22-gene assay and DNA methylation profiling on all patient samples.

RESULTS

We have HP/IHC, CMA, NanoString and methylation profiling for 54 infants and young children with medulloblastoma enrolled on HS-4. While indeterminate result occurred with CMA in three cases and NanoString in two cases, HP/IHC successfully assigned samples to SHH/WNT and non-SHH/non-WNT arms of the study in all 54 cases. We have HP/IHC, CMA and DNA methylation profiling for additional 33 patients. While pathology/IHC was indeterminate in two cases (one WNT and one group 3 MB), remaining cases accurately categorized medulloblastoma methylation subtype as WNT/SHH and non-WNT/non-SHH.

CONCLUSION

Due to the long turnaround time, waiting for medulloblastoma molecular subtype confirmation by DNA methylation array may delay treatment initiation. HS-4 data displays robust prediction of WNT/SHH versus non-WNT/non-SHH molecular subtypes by HP/IHC in comparison to DNA methylation profiling and provides a platform to initiate treatment based on HP/IHC while awaiting molecular information. In addition, these data support relying on histopathology for medulloblastoma subtypes in resource poor countries where methylation profiling is not readily available.
NFS-07. RESPONSE OF A CENTRAL NERVOUS SYSTEM (CNS) HEMANGIOBLASTOMA TO BELZUTIFAN IN A PEDIATRIC PATIENT WITH VON HIPPEL-LINDAU DISEASE (VHL)
Authors: Brandt Cierra M , Zajo Kristin N , Ronsley Rebecca , McAllister Aaron S , Sribnick Eric A , Salloum Ralph
Published: June 2024

BACKGROUND

VHL is a rare cancer predisposition syndrome which affects many organ systems, leading to renal clear cell carcinoma (RCC), pheochromocytoma, retinal angiomas and CNS hemangioblastomas. Surgical resection has traditionally been the mainstay of treatment of VHL-associated tumors. In 2021, belzutifan, a Hypoxia Inducible Factor 2-alpha inhibitor was approved by the Food and Drug Administration for the treatment of VHL-associated RCC based on efficacy in adults. There is a paucity of data in pediatric VHL patients with hemangioblastoma treated with this novel agent. Herein we present such a case.

CASE

A 15-year-old male, diagnosed with VHL caused by a de novo germline mutation at the age of 12, was found to have a left craniocervical junction lesion consistent with a hemangioblastoma on surveillance MRI. The lesion demonstrated growth upon serial imaging but remained asymptomatic. Due to location, the patient was started on medical treatment using once daily oral belzutifan (120mg) continuously, sperm banking was performed prior to initiation of therapy. Hematologic and metabolic laboratory values were monitored, in addition to regular physical examinations including blood oxygen saturation recordings. The first MRI on therapy (3 months after treatment started) demonstrated a major radiologic response using RANO criteria. Treatment has been overall very well tolerated with few treatment-related toxicities limited to CTCAE v5 grade 1 fatigue and grade 2 anemia. No dose reductions or interruptions were required. The patient remains on therapy and has completed 11 months of treatment with further reduction in the size of this target lesion.

CONCLUSION

Hemangioblastomas are preponderantly characterized by their highly vascular nature making surgical resection in some cases arduous depending on location. This unique pediatric case adds to the growing evidence that therapy with belzutifan may be a safe and efficacious option for VHL-associated CNS Hemangioblastomas. Prospective studies in children are needed.
NFS-12. CHOROID PLEXUS CARCINOMA IN PEDIATRIC PATIENTS WITH LI FRAUMENI SYNDROME (LFS) – CLINICAL COURSE AND THERAPEUTIC STRATEGIES
Authors: Perwein Thomas , Nussbaumer Gunther , Filipek Iwona , Piccolo Gianluca , Garrè Maria Luisa , Castellano Serafin , Lassaletta Alvaro , Salvador Hector , Baroni Lorena , Valera Elvis Terci , Scrideli Carlos , Jónsson Ólafur G , Scheinemann Katrin , Kilday John-Paul , Thomas Christian , Hasselblatt Martin , Kordes Uwe R , Adamski Jenny , Benesch Martin , Obrecht-Sturm Denise
Published: June 2024

BACKGROUND

Choroid plexus carcinoma (CPC) is a rare pediatric brain tumor occuring predominantly in infancy. It is commonly associated with the cancer predisposition Li-Fraumeni syndrome (LFS). Management of CPC patients with LFS is challenging and there is no accepted standard treatment. This multinational retrospective analysis aimed to describe the clinical characteristics and outcome of pediatric patients with LFS-associated CPC.

METHODS

We identified 32 patients (male, n=24; median age at diagnosis 2.1 years [range, 0.3-13.2]) with CPC (CNS WHO grade 3), and LFS confirmed by the presence of (likely) pathogenic TP53 germline variants. In 29 patients, LFS was diagnosed after CPC. Seventeen patients (53%) had a positive family history of LFS. CPC arose from the lateral ventricles in 30 patients, 14 had metastases at diagnosis.

RESULTS

Gross total resection was achieved in 21 patients during first-line treatment, as was subtotal resection in 9 and partial resection/biopsy in 2 patients. Thirty-one patients received first-line chemotherapy, with carboplatin/etoposide/vincristine most commonly used (n=9). Eight patients received upfront irradiation (CSI, n=5). Complete remission (CR) and partial remission (PR)/stable disease (SD) was achieved in 20 and 5 patients, respectively. Six patients did not respond to first-line treatment and one patient died during initial surgery. Nineteen patients experienced relapse or progressive disease (PD) with a median progression-free survival of 2.2±1.0 years and with metastases in 79%. At a median follow-up of 1.9 (0.1-17.7) years, fourteen patients were alive in CR (n=10), SD (n=1) or PD (n=3) and eighteen patients died (CPC-related, n=14; other malignancies, n=4). Progression-free and overall survival at 2 and 5 years were 52.2±9.1%/32.8±8.9% and 65.6±8.9%/51.8±10%, respectively.

CONCLUSIONS

LFS-related CPC carries a poor prognosis but should not be considered incurable. Outcomes are not dissimilar to non-LFS-related TP53-mutated CPC. International collaboration is the prerequisite for treatment standardization.
NFS-25. CANCER PREDISPOSITION SYNDROMES IN THE PROSPECTIVE PEDIATRIC BRAIN TUMOR COHORT
Authors: Kopecka Marie , Slamova Lucie , Sumerauer David , Trkova Katerina , Landova Lucie , Zamecnik Josef , Vicha Ales , Zapotocky Michal
Published: June 2024

BACKGROUND

The etiology of pediatric cancer remains largely unclear, with only a small proportion of patients (8-10%) harboring cancer predisposition syndromes (CPS). However, prospective studies evaluating CPS in pediatric neuro-oncology patients are scarce. We aimed to investigate the incidence and spectrum of CPS in this patient population.

METHODS

Newly diagnosed pediatric brain tumor patients from 2020 to 2023 were consented, and their germline DNA was sequenced using a DNA panel for next-generation sequencing (NGS) or whole-exome sequencing. Patients with previously known NF1, NF2, or TSC were excluded from the study.

RESULTS

A total of 164 consecutive patients from our center were enrolled over four years. Pathogenic germline variants (UV4 or UV5) were detected in 24 cases (14.6%). Half of these mutated genes are known to be associated with pediatric tumors. Examples include variants in TP53 (two patients with high-grade glioma), biallelic FANCD1 (medulloblastoma), SMARCE1 (meningioma), NF1 (high-grade glioma), NF2 (meningioma), MSH2 (medulloblastoma), and others. The second group of patients harbored pathogenic variants without confirmed associations with pediatric cancer, including heterozygous variants in MUTYH (n=3), FANC genes (n=2), NBN (n=2), PALB2, XPC, and pathogenic variants in WRN or CHEK2 (n=3). In addition to pathogenic variants in CHEK2, variants of uncertain significance, such as c.470T>C, were also identified (total n=8). The majority of patients with a CHEK2 variant were diagnosed with glial tumors. Notably, 8.3% of patients with pediatric low-grade gliomas (LGG) from our cohort harbored a CHEK2 germline variant.

CONCLUSIONS

The incidence of CPS in our cohort (14.6%) is higher than what is reported in studies evaluating all pediatric cancer patients. This percentage might be underestimated due to the exclusion of known phacomatoses. The role of some variants, including those in CHEK2, warrants further investigation. This study was supported by the Ministry of Health of the Czech Republic, grant number NU21-07-00419.
QOL-09. EQUI AND HIPPO: A STUDY ASSESSING THE FEASIBILITY AND ACCEPTABILITY OF HORSE THERAPY FOR CHILDREN, ADOLESCENTS AND YOUNG ADULTS IN REMISSION FROM A MEDULLOBLASTOMA
Authors: BERTOZZI Anne Isabelle , DEJEAN Morgan , BEAUDA Malory , BAUDOU Eloïse
Published: June 2024

INTRODUCTION

Psycho-social and motor disorders are common long-term sequalae in patients treated for a medulloblastoma during childhood. They often require long-term, multidisciplinary rehabilitation and post-therapeutic care that can be difficult to maintain over time. To address this common problem, we hypothesized that a horse therapy can re-engage children in their rehabilitation. The expected benefits of the horse therapy involve both psycho-social skills thought animal mediation (equitherapy) and motor skills using the horse’s three-dimensional movement (hippotherapy).

MATERIALS AND METHODS

We conducted a single-center prospective interventional trial including patients treated for medulloblastoma during childhood, aged 10 to 26, in complete remission. The intervention consisted on weekly 2-hours sessions of equitherapy and hippotherapy with a specialized physiotherapist and psychologist over a 4-month period (16 sessions per patient) in groups of 2 participants. The primary objective was to determine the feasibility of a rehabilitation program combining equitherapy and hippotherapy. The secondary objective was to assess changes in motor skills, balance, emotional feelings, self-esteem and quality of life at the end of the sessions, at 4 months and at 6 months using questionnaires and standardized and validated measurements.

RESULTS

The study began in April 2023 and is still ongoing. Six participants were included and four ended the intervention period. On this preliminary cohort, the recruitment rate was excellent with 100% of patients offered the program agree to take part. Three participants completed the program with a 100% adherence rate. All participants were very satisfied with their participation in the program. Analysis of second objective will be presented in the form of case reports.

CONCLUSION

The expected outcome of this study is to define a framework for the application of this practice, enabling a model of this rehabilitative management, and then to lead to dissemination and recognition of this activity, enabling larger-scale studies.