bluuebunny/crossref_metadata_2025_split huggingface dataset:
IMMU-01. EVALUATING THE IMPACT OF CAR DESIGN ON THE TUMOR IMMUNE MICROENVIRONMENT AND ANTI-TUMOR RESPONSE IN SYNGENEIC GLIOMA MODELS
Authors: Haydar Dalia , Crawford Jeremy , Chou Ching-Heng , Guy Cliff , Yi Zhongzhen , Zoine Jaquelyn , Gottschalk Stephen , Roussel Martine , Thomas Paul , Krenciute Giedre 
Published: June 2023

Abstract
B7-H3 CAR T-cells have limited efficacy in immunocompetent mouse models indicating a suppressive role of the tumor immune microenvironment (TIME). In this study, we set to optimize B7-H3 CAR structure and examine the effects of CAR design on brain TIME. We generated a panel of second-generation B7-H3-specific CARs with different transmembrane (CD8, CD28), costimulatory (CD28, 4-1BB), and activation (ζ, mutζ) domains. We then compared the cytolytic activity, expansion, and anti-tumor activity of T-cells expressing these CARs. Results showed that T-cells expressing B7-H3 CARs with CD28 transmembrane/costimulatory domains have superior efficacy in vitro. Yet, providing optimized costimulation and signaling did not induce superior anti-glioma efficacy of B7-H3 CAR T-cells in vivo. Additionally, incorporating 4-1BB signaling into CD28-based CAR T-cells by expressing 4-1BBL on their cell surface enhances the therapeutic efficacy and persistence of B7-H3 CAR T-cells in vitro. However, transgenic expression of 4-1BBL in CD28-based CARs was not associated with further enhanced anti-glioma efficacy of B7-H3 CAR T-cells in vivo. Next, using high-dimensional flow cytometry and spatial transcriptomic analyses, we show that suppressive tumor-associated macrophages (TAMs) infiltrate tumors in non-responder mice and they predominantly surround the tumor edges. Additionally, minimal T-cell infiltrates were observed in these tumors with predominantly exhausted and dysfunctional phenotypes. Analysis of gene-expression signatures early after CAR T-cell treatment revealed that tumors treated with CD28-based CARs differentially upregulate genes associated with inflammatory myeloid responses. While treatment with other signaling domains’ containing CARs upregulates pathways predictive of suppressive TAM and regulatory/dysfunctional T-cell responses. We show that global depletion of brain macrophages using CSF1R inhibitor exacerbates CAR T-cell anti-tumor activity. In summary, our results show that specific CAR domains induce an early inflammatory immune hub predictive of potent anti-tumor responses. Additionally, inflammatory macrophages are needed for successful CAR T-cell activation and anti-glioma responses.
IMMU-11. PRECLINICAL HIGH-RISK PEDIATRIC BRAIN TUMOR MODELS FOR IMMUNOTHERAPY: HURDLES AND THE WAY FORWARD
Authors: Mishra Deepak , Morris Shelli , Popovsk Dean , Bondoc Andrew , Kumar Shiva Senthil , Rutka James , Huang Annie , Olson Jim , Fouladi Maryam , Drissi Rachid 
Published: June 2023

Abstract
Despite recent therapeutic advancements in the treatment of pediatric brain tumors, high-risk brain tumors (pHRBT) remain the leading cause of cancer-related deaths in children. In recent years, immunotherapy has become a viable treatment option for several cancers including brain tumors. However, several factors have limited the use of immunotherapy in the treatment of pHRBT. For example, an "immunologically cold" tumor environment has been predominantly implicated in the failure of checkpoint inhibitors (ICIs) as monotherapy in pHRBT. Nevertheless, priming the effects of ICIs with epigenetic modulators through a process called “viral mimicry” that induces the expression of human endogenous retroviruses has the potential to enhance immunotherapy by sparking a T-cell mediated immune response. However, the inadequate understanding of the limitations of the preclinical models has prevented the development of efficient immunotherapy strategies for pHRBT. Although several studies and reviews have compiled some limitations of the available models, a hands-on experience using preclinical models for ICIs testing has not been fully communicated. Here, we share our bedside to bench experience with syngeneic and humanized mouse models of DIPG, ATRT, and medulloblastoma using ICIs therapy in conjunction with an epigenetic alteration. We will present and discuss the limitations of mouse models for the development of immunotherapies for pHRBT. For instance, our results indicated that the baseline levels of MHC-I expression in patients’ DIPG tumors were comparable to matched normal tissue. However, these levels were significantly lower in mouse DIPG tumors. To compensate for this difference, we treated mice with IFN-γ in combination with an epigenetic modulator. Surprisingly, the addition of INF-γ had a negative effect on animal overall survival compared to the treatment with the epigenetic modulator alone. Together, our experience demonstrated the importance of suitability assessment of current models for developing and translating successful immunotherapy strategies to treat pHRBT.
IMMU-15. PHASE I TRIAL OF GD2.CART-CELLS AUGMENTED WITH A CONSTITUTIVELY ACTIVE INTERLEUKIN-7 RECEPTOR (C7R) FOR TREATMENT OF HIGH-GRADE PEDIATRIC CNS TUMORS
Authors: Lin Frank , Stuckert Austin , Tat Candise , Moeller Karen , White Mark , Ruggieri Lucia , Zhang Huimin , Lindsay Holly , Baxter Patricia , Malbari Fatema , Aldave Guillermo , Chintagumpala Murali , Parsons D Williams , Brenner Malcolm , Heslop Helen , Rooney Cliona , Omer Bilal 
Published: June 2023

Abstract

BACKGROUND
Treatment of pediatric CNS tumors with T-cells modified with chimeric antigen receptors (CARTs) provides an innovative approach. We employ GD2-directed CART-cells (GD2.CARTs) modified to express a constitutively active interleukin-7 receptor (C7R) to increase GD2.CART survival and function independent of external cytokines, thereby augmenting activity against GD2-expressing CNS malignancies.

METHODS
In a Phase I study, we investigated the safety of intravenous GD2.CART therapy for pediatric patients with H3K27-altered diffuse midline glioma (DMG) or other GD2-expressing recurrent CNS tumors. We used a 3 + 3 design in which the first treatment cohort received GD2.CARTs without C7R, while subsequent cohorts received GD2.CARTs co-transduced with C7R (C7R-GD2.CARTs) at two dose levels. As a secondary endpoint we measured disease response 6 weeks after CART infusion.

RESULTS
12 patients were treated without dose limiting toxicity. The first cohort (n=3: thalamic DMG, spinal DMG, recurrent AT/RT) received GD2.CARTs without C7R at 1x107 cells/m2. No toxicity was observed and all 3 patients had clinical neurological improvement lasting approximately 4 weeks before disease progression. The next two cohorts received C7R-GD2.CARTs at 1x107 cells/m2 (n=3) and 3x107 cells/m2 (n=6). Mild tumor inflammation associated neurotoxicity was observed in 7 of 9 (78%) patients, which was controlled with anakinra without need for corticosteroids. Cytokine release syndrome (CRS) was observed in 5 of 9 (56%) cases [grade 1 (n=4), grade 3 (n=1)], resolving with tocilizumab. Eight of 9 patients receiving C7R-GD2.CARTs had clinical improvement or stability for more than 8 weeks (up to 10 months at last follow-up) and received repeat cell infusions at 6 week intervals (range 2-4 cycles). Partial radiologic responses were confirmed for 2 of 7 (29%) patients with DMG.

CONCLUSION
Intravenous treatment with C7R-modified GD2.CARTs was well tolerated in children with CNS tumors, and the duration of clinical improvement was extended by C7R co-expression.
IMMU-20. EVALUATION OF B7-H3 NANOBODY CAR-T CELLS IN PEDIATRIC GLIOBLASTOMA
Authors: Fanuzzi Mia , Cole Allison , Singh Mohit Pratap , Li Dan , Wang Ruixue , Liang Tianyuzhou , Ho Mitchell , Nellan Anandani 
Published: June 2023

Abstract
Chimeric antigen receptor (CAR)-T cell therapies are an undoubted success in childhood acute lymphoblastic leukemia; however, this success has not translated clinically to any childhood solid tumor. B7-H3 has been found to be highly expressed in pediatric brain tumors and correlates with tumor progression and poor prognosis. We utilized a novel nanobody based CAR-T cell which can bind tumor antigens with high affinity. We hypothesize that anti-B7-H3 nanobody CAR-T cells mediate more potent antitumor effects both in vitro and in vivo compared to existing antibody-based B7-H3 CAR-T cells. High expression of B7-H3 was confirmed on the surface of two pediatric glioblastoma cell lines by flow cytometry and Quantibrite staining. B7-H3 nanobodies isolated from camel phage libraries were cloned into lentiviral CAR-T cell constructs. We manufactured CAR-T cells by lentiviral transduction of human T cells. Glioblastoma tumor cells were co-cultured with B7-H3 CAR-T cells vs. control T cells. We confirmed B7-H3 specific cytokine release by CAR-T cells via ELISA and effective tumor cell killing via two different cytotoxicity assays (impedance or luciferase based). Nanobody based B7-H3 CAR-T cells exhibited statistically significant higher cytokine release and cytotoxicity compared to antibody based B7-H3 CAR-T cells. In vivo studies are currently evaluating the efficacy of intracerebroventricular delivery of B7-H3 CAR-T cells against two orthotopic glioblastoma models utilizing multiple human donor T cells in immunocompromised mice. We are simultaneously developing a syngeneic orthotopic glioblastoma model to evaluate the nanobody based B7-H3 CAR-T cell cross-reactive in mice utilizing an immunocompetent model. Careful investigation of CAR-T cell therapy in appropriate immunocompetent in vivo models is needed to develop effective immunotherapy for clinical application.
IMMU-23. RESEARCH ON MULTI-ANTIGEN T CELL INFUSION AGAINST NEURO-ONCOLOGIC DISEASE (ReMIND)
Authors: Cruz Conrad Russell , Gomez Stephanie , Geiger Ashley , Grant Melanie , DiCioccio Rachel , Fortiz Maria , Lang Haili , Datar Anushree , Shibli Abeer , Reynolds Emily , Lazarski Christopher , Wachspress Mariah , Pezzella Gloria , Gomez Daisy , Tanna Jay , Hoq Fahmida , Hanley Patrick , Kilburn Lindsay , Rood Brian , Packer Roger , Bollard Catherine , Hwang Eugene 
Published: June 2023

Abstract

INTRODUCTION
Pediatric patients with recurrent or progressive central nervous system (CNS) tumors have poor prognoses and clearly require improved therapies. Previous studies that used ex vivo expanded T cells show promising efficacy against viral infections. The polyclonal nature of these T cells, capable of recognizing multiple antigens, can be of potential benefit to patients with high-risk brain tumors, where intratumoral heterogeneity plays a prominent role in therapeutic resistance.

METHODS
Patients with CNS malignancies received T cells in a phase I dose escalation study (NCT03652545). The safety and feasibility of infusing ex vivo expanded, autologous T cells was determined in patients with newly diagnosed diffuse intrinsic pontine gliomas (DIPGs, Arm A, infused up to 5 months post irradiation) or recurrent/progressive non-brainstem CNS malignancies with (Arm C) or without (Arm B) lymphodepletion.

RESULTS
As of April 2023, 46 patients were enrolled on study. A total of 30 patients received infusions (8 in Arm A, 18 in Arm B, 4 in Arm C) that were well tolerated. One patient experienced a severe potentially-related adverse event (tumor swelling). In Arm A (DIPG), median OS was 12 months post-diagnosis (one patient survived for 31 months). In arm B, median OS was 11 months post T cell infusion, with 6 patients still alive (longest four years after treatment). In Arm C, 3/4 patients remain alive 4+ months from infusion (one patient had a potential pseudoprogression based on scans).

CONCLUSIONS
Autologous T cells can be expanded from pediatric patients with CNS malignancies and are well tolerated. Data suggests that TAA-T products may induce an anti-tumor response, with or without lymphodepletion, and prolong survival. Efforts are ongoing to analyze immune correlates which are focused on evaluating circulating T cell clones and investigating changes in peripheral blood gene signatures and circulating plasma proteins.
LGG-05. IMAGING-BASED DEEP LEARNING FOR EVENT-FREE SURVIVAL PREDICTION IN PATIENTS WITH PEDIATRIC LOW-GRADE GLIOMA
Authors: Zapaishchykova Anna , Hayat Hasaan , Ye Zezhong , Vajapeyam Sridhar , Chopra Rishi Balraj , Boyd Aidan , Liu Kevin X , Aerts Hugo J W L , Bandopadhayay Pratiti , Haas-Kogan Daphne A , Nabavidazeh Ali , Resnick Adam C , Mueller Sabine , Poussaint Tina Y , Cooney Tabitha M , Kann Benjamin H 
Published: June 2023

Abstract
Pediatric low-grade gliomas (pLGGs) have heterogeneous outcomes, making individualized clinical decision-making challenging. Imaging-based biomarkers for progression and/or recurrence may better risk-stratify pLGG patients and guide management. We developed and externally validated a deep learning (DL) algorithm to predict event-free survival (EFS) in pLGG using multi-institutional databases. We collected linked, T2-weighted diagnostic Magnetic Resonance Images (MRI) and clinical data for patients with WHO grade 1-2 pLGG (diagnosed from 1991-2017) from the Children’s Brain Tumor Network (CBTN, n=176, median follow-up: 3.7 years, IQR=2-6.8 years) for model development and internal validation, and Boston Children’s Hospital (BCH, n=219, median follow-up: 8.8 years, IQR=4-13.4 years) for external validation. Leveraging a self-supervised learning approach, we trained a DL Unet model for tumor segmentation and used it for extracting image features. We combined 12 DL-imaging features with three clinical variables (age, sex, and surgical resection status (gross total/subtotal/no resection) and trained a Deep Cox Mixtures(DCM) model for survival analysis. We externally validated the performance of three models: clinical, DL-imaging, and combined DL-imaging and clinical. The combined DL-imaging and clinical model outperformed the clinical alone and DL-imaging alone models for prediction of 3-year EFS (time-dependent AUC: 0.85, 0.73, 0.53, respectively) with improved calibration (Integrated Brier Score: 0.08, 0.13, 0.15, respectively). Using the combined DL-imaging and clinical model output, patients were divided into low and high-risk groups based on mean event probability (3-year EFS 53% vs 86%, p=0.02). Variables associated with poor EFS were imaging score, lower age, and lack of gross total resection. In conclusion, deep learning-derived, MRI-based imaging features may improve prediction of event-free survival and risk stratification for patients with pLGG.
LGG-15. SINGLE-NUCLEUS AND BULK RNA SEQUENCING OF PEDIATRIC PILOCYTIC ASTROCYTOMAS REVEALS CNS LOCATION-ASSOCIATED TUMOR CELL AND MICROENVIRONMENTAL HETEROGENEITY
Authors: Lammers Julie A S , Rozowsky Jacob S , Kranendonk Mariëtte E G , Schouten-van Meeteren Antoinette Y N , Meijer Lisethe , Calkoen Friso G , Hoving Eelco W , Wesseling Pieter , van der Lugt Jasper , Kester Lennart A 
Published: June 2023

Abstract

BACKGROUND
Pilocytic astrocytomas are the most common pediatric central nervous system (CNS) tumors. While the overall survival is generally favorable, a substantial part of the patients relapse, resulting in long-term complications. Additionally, pilocytic astrocytomas show limited genetic heterogeneity and are often driven by a single molecular event. The role of the tumor microenvironment (TME) in disease progression is yet unknown. Here, we aimed to delineate the composition of the tumor in pilocytic astrocytomas originating from different CNS locations.

METHODS
We collected 112 tumor samples, out of which a subset (n = 10) was used for single-nucleus RNA-sequencing (10X Genomics). These tumor samples originated from various CNS locations: posterior fossa (n = 64), supratentorial (n = 38) and spinal (n = 10). Clinical characteristics, DNA methylation profiles, whole exome/genome sequencing and bulk RNA sequencing data were available for most of these samples.

RESULTS
Single-nucleus RNA-sequencing revealed substantial heterogeneity amongst both tumor and TME cells, which mainly associated with tumor location. While a large proportion of tumor cells expressed gene signatures related to oligodendrocyte precursor cells (OLIG1/2, PDGFRA), a subset of tumor cells was characterized by high expression of astrocyte genes (AQP4, GFAP). Moreover, we defined multiple populations of lymphocytes and myeloid cells, with the latter constituting the vast majority of non-neoplastic cells. Deconvolution of the bulk RNA sequencing data showed heterogeneous involvement of the TME. Additionally, the relative abundances of TME cells varied considerably across CNS locations. We are currently correlating the relative proportions of tumor and TME cell populations with clinicopathological data.

CONCLUSION
Single-nucleus RNA-sequencing demonstrated transcriptional differences in both tumor cell states and TME cell populations, which associated with CNS location. Future research should elucidate the importance of the cellular composition of the tumor in pilocytic astrocytomas.
LGG-19. MULTI-MODALITY CHARACTERIZATION OF PEDIATRIC LOW-GRADE GLIOMA: THE ADDED VALUE OF DIFFERENT DATA MODALITIES
Authors: Haldar Debanjan , Kazerooni Anahita Fathi , Mahtabfar Aria , Khalili Nastaran , Familiar Ariana , Kraya Adam , Kim Meen Chul , Tu Wenxin , Haldar Shuvanjan , Bagheri Sina , Anderson Hannah , Viswanathan Karthik , Shaikh Ibraheem , Ware Jeffrey , Storm Phillip , Vossough Arastoo , Resnick Adam , Nabavizadeh Ali 
Published: June 2023

Abstract
Characterization of pediatric low-grade glioma (pLGG) remains a significant challenge in the field of neuro-oncology, with a need for more effective precision diagnostics. Multi-modal analysis, which incorporates data from varied sources, has the potential to provide a comprehensive understanding of the underlying biology of pediatric brain tumors. Despite its potential, the utilization of true multi-modality clustering remains limited in pediatric brain tumor research. In this study, we aimed to address this gap by using a clustering model that incorporated genomics, radiomics, and clinical variables (age, sex, and tumor location) to group patients into distinct clusters. 103 patients with pLGGs were included. Mutations data was derived from whole genome sequencing obtained through the PedCBioportal. Radiomic data was obtained from MR imaging through the Children’s Brain Tumor Network and included features from pre- and post-contrast T1, T2, FLAIR, and ADC sequences. Categorical variables included sex (male vs female), genetic mutation status for 10 selected genes (BRAF, FGFR1, TSC1, TSC2, NF1, MYB, EGFR, ALK, IDH1, and RB1) that are known to play a role in the pathogenesis of pLGG (mutated vs non-mutated), and tumor location (9 categories). Continuous variables included age (days) and radiomic features. All numerical variables were normalized and reduced into principal components that captured 90% of the variance in the data prior to clustering. Various clustering iterations were performed incorporating combinations of radiomic, genomic, and clinical data. Our models identified two distinct clusters and the PFS differences between clusters approached statistical significance with the integration of information from all modalities when compared to any combination of subsets of data, highlighting the complementary value of these modalities in providing a comprehensive characterization of pLGG. This study provides preliminary evidence for the utility of multi-modality data clustering in improving our understanding of pLGG and supports further investigation into this approach.
MDB-08. THYROID HORMONES INHIBIT MEDULLOBLASTOMA PROGRESSION THROUGH INDUCING TUMOR CELL DIFFERENTIATION
Authors: Yang Zeng-jie , Yang Yijun , Heller Allie , Rives Silvia Valdes 
Published: June 2023

Abstract
Hypothyroidism is commonly detected in patients with medulloblastoma (MB), a pediatric brain tumor, which is generally considered as a treatment-related complication. Although reduced levels of thyroid hormone (TH) significantly correlate with poor survival of patients with MB, the possible link between TH signaling and MB pathogenicity is unknown. Here, we found that TH plays a critical role in MB pathogenicity through regulating the terminal differentiation of tumor cells. In the absence or with reduced levels of TH, unliganded TRα (a nuclear TH receptor) physically interacts with EZH2 to epigenetically repress the expression of NeuroD1, a transcription factor dictating terminal differentiation of neuronal progenitors and MB cells. However, TH reverses EZH2-mediated repression of NeuroD1 through interfering with the binding between EZH2 and TRα, thereby stimulating terminal differentiation of tumor cells and repressing MB pathogenicity. Moreover, TH promotes extensive differentiation and suppresses the proliferation of tumor cells from different molecular subgroups of MB5 including hedgehog (HH) group as well as group 3 (G3) MB, suggesting that TH-induced differentiation is not restricted by oncogenic mutations in tumor cells. Consequently, TH treatment significantly inhibits the in vivo growth of SHH- and G3-MB via stimulating tumor cell differentiation, with no induction of tumor cell apoptosis or death, indicating that TH signaling represents a novel therapeutic entry-point for broad treatment of MB. These findings elucidate the mechanisms underlying terminal differentiation of MB cells, establish an unprecedented association between TH signaling and MB progression. Our studies provide compelling evidence for a promising tumor therapeutic modality by promoting tumor cell differentiation.
MDB-18. MOLECULARLY-DEFINED MEDULLOBLASTOMA: POPULATION-LEVEL PATTERNS IN THE UNITED STATES, 2018-2019
Authors: Ostrom Quinn T , Price Mackenzie , Neff Corey , Cioffi Gino , Waite Kristin A , Kruchko Carol , Barnholtz-Sloan Jill S 
Published: June 2023

Abstract
Medulloblastoma is one of the most common types of brain and other CNS tumors among the pediatric population in the US. Molecularly-defined brain tumor histopathologies—including medulloblastoma subtypes—were incorporated into US cancer registry reporting for individuals with brain tumors beginning in 2018. We assessed the epidemiology and overall survival (OS) patterns for medulloblastoma in children and adolescents, highlighting molecularly-defined subtypes. Children and adolescents (0-19 years) that were histopathologically diagnosed with medulloblastoma from 2018-2019 and had brain molecular marker data were identified within the Commission on Cancer’s National Cancer Database (NCDB) and Central Brain Tumor Registry of the United States databases, which combines data from CDC’s National Program of Cancer Registries (NPCR) and NCI’s Surveillance, Epidemiology, and End Results (SEER) Programs. Incidence rates per 100,000 population with 95% confidence intervals (95CI) were estimated for histopathologies with ≥16 cases. One-year OS was estimated using NCDB data for histopathologies with ≥50 cases with follow-up through 2020 using Kaplan-Meier methods. There were 601 cases of histopathologically-confirmed medulloblastoma diagnosed in children and adolescents from 2018-2019, 39.6% of which had available molecular subtype information. Overall incidence of medulloblastoma was 0.37 (95CI=0.34-0.40). Incidence of medulloblastoma subtypes was 0.05 (95CI=0.04-0.06) for SHH-activated & TP53wt, 0.02 (95CI=0.01-0.02) for WNT-activated, 0.08 (95CI=0.06-0.09) for nonWNT/nonSHH, while SHH-activated & TP53mut was too rare to calculate incidence. One-year OS for all medulloblastoma was 96.6% (95CI=92.1%-100.0%). One-year OS for nonWNT/nonSHH was 96.6% (95CI=92.8%-100.0%), and for SHH-activated & TP53wt was 93.7% (95CI=87.1%-100.0%). Other subtypes occurred too rarely to calculate survival. Our findings provide the initial US epidemiological estimates for molecularly-defined medulloblastoma histopathologies in children and adolescents. As improvements in collection completeness lead to increased molecular subtype availability, the robustness of these estimates will increase. Collection of these data are essential for understanding the epidemiology of this important childhood and adolescent brain tumor.