bluuebunny/crossref_metadata_2025_split huggingface dataset:
IMMU-18. ENHANCING GD2.CAR T CELL THERAPY FOR DIFFUSE MIDLINE GLIOMA WITH LSD1 AND HDAC INHIBITORS
Authors: Murdaugh Rebecca L , Shekar Meghan , Eberl Brittany R , Tremblay Jack R , Richard Rosemary U , Nguyen Linh , Omer Bilal , Anastas Jamie N 
Published: June 2024

Abstract

BACKGROUND
Chimeric antigen receptor T cells against the glycolipid GD2 (GD2.CARTs) have shown promise against Diffuse Midline Glioma (DMG) in clinical trials but are not yet curative. Previous studies in neuroblastoma demonstrate that histone deacetylase inhibitor (HDACi) treatment can increase GD2 on tumor cells and improve targeting by GD2.CARTs. Our lab previously found that simultaneous HDACi and lysine-demethylase 1 inhibitor (LSD1i) treatment in DMG cells causes synergistic alterations in gene expression and reduces DMG growth. Here, we find that treating GD2-low DMG cell lines with combinations of LSD1i and HDACi improves DMG response to GD2.CARTs.

METHODS
Surface expression of GD2 before and after LSD1i/HDACi treatment were analyzed using immunofluorescence microscopy and flow cytometry. The cytotoxicity of GD2.CARTs against DMG cells was determined from co-culture experiments and in patient-derived orthotopic xenograft models using flow cytometry and bioluminescent imaging.

RESULTS
Since low target antigen expression is one mechanism by which tumor cells can escape CAR T cell therapy, we profiled GD2 expression on 9 different H3K27M-mutant DMG cell lines. This analysis shows that only 5 of the 9 cell lines exhibit high GD2 expression while the remaining 4 lines have low GD2 expression. When treating these cell lines with GD2.CARTs, we find that low GD2 expression on DMG cells correlates with tumor cell escape and resistance to GD2.CARTs. Treating GD2-low DMG cells with LSD1i+HDACi increases GD2 expression and enhances tumor cell targeting by GD2.CARTs in subsequent co-culture assays. Further studies in mice bearing GD2-low DMG tumors were initially GD2.CART-insensitive but showed reduced tumor growth when pre-treated with LSD1i+HDACi before intravenous GD2.CART infusion.

CONCLUSIONS
These studies suggest that variable GD2 expression is a major driver of DMG resistance to GD2.CARTs and that LSD1i+HDACi pre-treatment may improve DMG patient responses to GD2.CART therapy by increasing target antigen expression.
IMMU-19. COMBINATION IMMUNOTHERAPY SEQUENCE MATTERS: VACCINE PRIOR TO ONCOLYTIC HSV VIROTHERAPY ENHANCES TUMOR-SPECIFIC T CELL RESPONSES AND EFFICACY
Authors: Kang Kyung-Don , Totsch Stacie K , Ishizuka Andrew S , Gary Sam E , Rocco Abbey , Fan Aaron , Zhou Li , Valdes Pablo A , Lee SeungHo , Li Jason , Peruzzotti-Jametti Luca , Blitz Sarah , Garliss Christopher M , Johnston James M , Markert James M , Lynn Geoffrey M , Bernstock Joshua D , Friedman Gregory K 
Published: June 2024

Abstract

BACKGROUND
Safety and preliminary efficacy have been demonstrated with intratumoral oncolytic, engineered HSV immunotherapy; however, few responses have been durable, suggesting that augmented, prolonged anti-tumor T cell responses are likely required to maintain tumor remission. We hypothesized that combining the direct oncolytic effect and innate immune stimulus of oHSV with a vaccine that fosters T cell mediated immunity would lead to more prolonged tumor responses.

METHODS
We examined the preclinical efficacy of combining intratumoral oHSV with an intravenous (via tail vein) self-assembling nanoparticle vaccine co-delivering peptide antigen to E7 and Toll-like receptor-7 and -8 agonists (TLR-7/8a), termed ‘SNAPvax™’, compared to either therapy alone or control in a TC-1 E7-expressing tumor model in immunocompetent mice. We also assessed how SNAPvax™ timing (before or after oHSV) affected efficacy, viral replication by viral recovery assay, and T cell activation and responses via intracellular cytokine staining of CD8+ T cells in the blood and tetramer staining.

RESULTS
The oHSV-vaccine combination prolonged survival compared to control or either agent alone. Critically, survival was significantly enhanced when SNAPvax was given before oHSV compared to after oHSV. Increased effectiveness was associated with reduced tumor volume, increased tumor antigen specific CD8+ T cells, and amplified viral recovery.

CONCLUSIONS
These results demonstrate the criticalness of combination immunotherapy timing with improved efficacy seen when vaccine was given prior to oHSV, which was mediated by tumor specific CD8+ T cells and increased viral replication. Our data provide preclinical support for translation of this novel combination therapy to clinical trial.
IMMU-20. INNATE IMMUNE EVASION IN MYC-AMPLIFIED MEDULLOBLASTOMA
Authors: Vo Jeremy , Mitra Juni S , Knox Aaron , Picard Daniel , Vibhakar Rajeev , Hankinson Todd , Mitra Siddhartha S 
Published: June 2024

Abstract

BACKGROUND
While major advances have been made in improving the quality of life and survival of children with most forms of medulloblastoma (MB), those with MYC-driven tumors (Grp3-MB) still suffer significant morbidity and mortality. Here, we report a cell surface proteome analysis of Group3-MB cell lines after direct MYC inhibition to identify changes in surface proteins and sensitivity to macrophage-mediated phagocytosis.

METHODS
We had previously demonstrated the preferential activity of HDACi (CI994) in MYC-driven medulloblastoma. CI-994, showed significant cell viability reduction mediated by reduction in the MYC (mRNA and protein), induction of apoptosis in MYC-driven medulloblastoma. In this study, we directly inhibited MYC using MYCi975 and OMO-MYC and carried out a cell surface proteomic analysis on Group3-MB cell lines to reveal CD24 and CD59 as potential immune evasion markers. While CD24 is a potential don’t eat me signal, CD59 is a ubiquitously expressed cell-surface glycosylphosphatidylinositol-anchored protein that acts as an inhibitor to the membrane attack complex and protects cells from CDC. In certain tumors, CD59 expression is enhanced, posing a significant obstacle to treatment by hindering effective monoclonal antibody-induced CDC. We use inhibitors to CD24 and CD59 to confirm their role as innate immune evasion proteins in Group 3MB.

RESULTS
Meta-analysis of published datasets reveals CD24 and CD59 as strong prognostic indicators in Group3-MB as well as within the Group3g-subtype. Inhibition of MYC reduces surface levels of CD24, increasing macrophage-mediated phagocytosis. The use of a blocking anti-CD24 mAb significantly enhanced macrophage-mediated phagocytosis. Furthermore, a significant reduction in surface expression was observed in CD59. Blocking CD59 mAb significantly enhanced anti-CD47 mAb mediated phagocytosis. Combined treatment of anti-CD24 and anti-CD47 significantly enhanced the survival of Grp3-MB tumor-bearing mice.
IMMU-22. B7-H3 NANOBODY CAR-T AND SOLUBLE TREM2 GENETICALLY ENGINEERED MYELOID CELL THERAPY IN MURINE SYNGENEIC GLIOBLASTOMA
Authors: Cronk James C , Meskini Rajaa El , Fanuzzi Mia , Atkinson Devon , Householder Debbie , Puebla Mariela , Bassel Laura , Ball Brendan , Montalvan Emily San Andres , Li Dan , Kaczanowska Sabina , Ho Mitchell , Kaplan Rosandra N , Ohler Zoe Weaver , Nellan Anandani 
Published: June 2024

Abstract

BACKGROUND
Myeloid immunosuppression can be a major impediment to CAR-T cell therapy for CNS tumors. Importantly, CAR-T cells are often evaluated in immunocompromised mice which cannot accurately recapitulate the tumor immune response or tumor microenvironment. CNS tumor macrophages express TREM2, an important driver of immunosuppression. This study combines B7-H3 targeting nanobody CAR-T cells which are cross reactive in humans and mice (currently being evaluated for clinical development) with genetically engineered myeloid cells (GEMys) expressing soluble TREM2 (sTREM2) in a syngeneic mouse model of glioblastoma (GBM), with the aim of blocking TREM2-mediated immunosuppression to enhance CAR-T cell function.

METHODS
Syngeneic murine GBM, designed to mimic human GBM and generated at the Center for Advanced Preclinical Research (CAPR), was used for all studies. B7-H3 nanobody CAR-T cells were generated from mouse splenic T cells. In vitro tumor killing assays were performed by xCELLigence. sTREM2 GEMys were generated from bone marrow progenitor cells using lentiviral transduction. For in vivo studies, mice underwent orthotopic implantation of tumors and placement of an MRI-compatible, permanent catheter-port system for serial intracerebroventricular (ICV) administration of cell therapies. Mice were treated with CAR-T and/or GEMy therapies, evaluated weekly for tumor burden by MRI, and were monitored for survival.

RESULTS
Syngeneic GBM expression of B7-H3 was confirmed by flow cytometry, immunofluorescence, and western blot. B7-H3 nanobody CAR-T cells demonstrated effective killing of GBM by xCELLigence. sTREM2 GEMys were successfully generated and confirmed to produce sTREM2. Cell therapies were successfully infused ICV via the implanted catheter-port system, demonstrating safety and feasibility of this model for serial ICV cellular therapy.

CONCLUSIONS
B7-H3 nanobody CAR-T cells were validated against syngeneic GBM, and we have demonstrated safety and feasibility of ICV catheter administration of cellular therapies in vivo. Future studies will continue to evaluate in vivo timing and efficacy of CAR-T and GEMy therapy.
LGG-02. ELUCIDATING THE ROLE OF FGFR1 ALTERATIONS IN PEDIATRIC GLIOMAS
Authors: Apfelbaum April A , Morin Eric , Bahadur Sher , Sturm Dominik , Novikov Dana , DiGiacomo Jeromy , Cameron Amy , Rechter Patrick , Cusick Margaret M , Oh Sehee , Jeon Hyesung , Vogelzang Jayne , Jones Jacquelyn , Bossi Connor , De Nguyen Quang- , Jones David T W , Eck Michael J , Fischer Eric S , Ligon Keith L , Bandopadhayay Pratiti 
Published: June 2024

Abstract

BACKGROUND
Pediatric brain cancers are the leading cause of cancer-related deaths in children. We (and others) have recently found that close to 10% of all pediatric gliomas, encompassing low-grade gliomas (LGGs) and high-grade gliomas (HGGs), harbor recurrent driver alterations in FGFR proteins, most frequently FGFR1, the gene encoding Fibroblast Growth Factor Receptor 1. In pediatric gliomas, FGFR1 alterations present as either structural variants (SVs), including kinase duplications and fusion proteins, or kinase-activating single nucleotide variants (SNVs). Recurrent FGFR1 alterations represent a promising therapeutic target for precision medicine approaches, however a challenge has been the lack of clinical trials for FGFR inhibitors. A major goal of this project is to identify preclinical FGFR inhibitor candidates for FGFR1-altered pediatric gliomas.

METHODS
We have generated isogenic mouse and human neural stem cell (NSC) models driven by FGFR1 and BRAF alterations commonly seen in pediatric gliomas to test the oncogenic properties and therapeutic capacities of these alterations.

RESULTS
We found that NSC lines grow independent of growth factors and form tumors in mice. RNA-sequencing of these lines revealed the FGFR1-altered lines are enriched in neuronal gene programs. The FGFR1-altered models are exquisitely sensitive to the four FDA-approved panFGFR inhibitors Infigratinib, Erdafitinib, Pemigatinib, and Futibatinib. However, the FGFR1 SNV + PTPN11 co-occurring SNV line is the least sensitive to FGFR inhibition, which suggests combination therapies may be needed. Combination drug studies with FGFR inhibition in our FGFR1-altered lines reveal the best synergy with mTOR inhibition. Finally, we present examples of case studies of patients with FGFR1-altered tumors treated with targeted inhibitors.

CONCLUSIONS
Taken together, our studies have established models that have generated key insights into the biology of FGFR1-altered gliomas and how to best target them therapeutically.
LGG-03. PREDICTIVE VALUE OF ACQUIRED NYSTAGMUS FOR PEDIATRIC BRAIN TUMOR ASSOCIATED VISUAL IMPAIRMENT: A RETROSPECTIVE STUDY
Authors: Teeuwen Sophie , Oostenbrink Rianne , Porro Giorgio , Meijer Lisethe 
Published: June 2024

Abstract

BACKGROUND
Visual impairment (VI), defined as visual acuity (VA) loss or visual field (VF) defects, is common in pediatric brain tumors of the optic pathway and may impact the quality of life. VI is a challenge to establish, especially in young children. However, pediatric brain tumor patients might concurrently have acquired nystagmus (AN), which can easily be observed. The aim of this study was to investigate whether AN is predictive of VI in pediatric brain tumor patients. If correlated, AN could be an early warning sign for brain tumor related VI, warranting MRI scanning to prevent further visual deterioration, thus decreasing morbidity and mortality.

METHODS
Data on tumor characteristics, VA (in LogMAR), VF, (type of) AN and other ophthalmic investigations were collected from the medical records of pediatric brain tumor patients in the Máxima Pediatric Brain Tumor Ophthalmology cohort (MP-BT-O cohort). These characteristics between children with (nystagmus group) and without (control group) AN were compared to determine the predictors of VI.

RESULTS
The MP-BT-O cohort consists of 389 children (≤18y) with a brain tumor who had visual assessment, 95 children had AN (24.4%). The mean best corrected visual acuity (BCVA) was 0.10 LogMAR [CI 0.06-0.14] in the control and 0.50 LogMAR [CI 0.35-0.66] in the nystagmus group (p&lt;0.001). Nystagmus type was found to be a significant predictor of VI (p&lt;0.001). Specifically horizontal AN (a decrease in BCVA of 0.75 LogMAR, p&lt;0.001) and mixed AN (a decrease in BCVA of 0.61 LogMAR, p&lt;0.001) were independent predictors of VI, corrected for tumor location (p=0.04) and age at diagnosis (an increase in BCVA of -0.02 LogMAR per year, p&lt;0.001).

CONCLUSIONS
Acquired nystagmus, especially horizontal and mixed nystagmus, is an independent predictor of VI in pediatric brain tumor patients and should be interpreted as a warning sign for the presence of VI.
LGG-12. INTEGRATED CLINICAL AND MOLECULAR CHARACTERIZATION OF 200 DISSEMINATED PEDIATRIC LOW-GRADE GLIOMAS
Authors: Levine Adrian , Bennett Julie , Li Cyril , Rana Mansuba , Yuditskiy Richard , Ho I-Chen , Haizel-Cobbina Joseline , Hansford Jordan , Luck Amanda , Ludlow Louise , Eisenstat David , Toledano Helen , Masoud Roaya , Fukuoka Kohei , Yamasaki Kai , Nakano Yoshiko , Mushtaq Naureen , Minhas Khurram , Bukhari Syed Ibrahim , Stuecklin Ana Guerreiro , Weiser Annette , Jadrijevic-Cvilje Filip , Fleming Adam , Campbell Shawde , Cacciotti Chantel , Erker Craig , van Landeghem Frank , Wilson Bev , Black Karina , MacNeil Mary , Cheng Sylvia , Dunham Chris , Larouche Valerie , Giannakouros Panagiota , Fonseca Adriana , Williamson Lane , Plant-Fox Ashley , Levy Jean Mulcahy , DeMarsh Samantha , Vega José Velázquez , Patil Prabhumallikarjun , Nasrallah MacLean , Santi-Vicini Mariarita , Nelson Ernest , Graham Richard , Raskin Scott , Fernandes Igor , Dewan Michael , Tabori Uri , Hawkins Cynthia 
Published: June 2024

Abstract
Pediatric low-grade gliomas (PLGG) have excellent outcomes overall but are a major clinical challenge when disseminated. Diffuse leptomeningeal glioneuronal tumor (DLGNT) is a recognised entity both clinically and pathologically, however many disseminated LGG (DLGG) fall outside this diagnosis. To better understand the clinical and molecular features of DLGG as well as risk factors for dissemination, we assembled an international consortium of 30 sites, contributing over 200 patients with clinical annotation, along with genomic and methylation profiling. DLGG have worse progression-free (PFS) and overall survival (OS) than PLGG overall (p&lt;0.0001). Seventy (35%) presented with a localized mass and secondary dissemination, including some with initial gross-total resection. The most common growth pattern observed (n=77, 40%) is a dominant suprasellar/optic pathway tumor with leptomeningeal drop-metastases involving the brainstem and spinal cord. Only 27 (14%) patients had diffuse tumors (without an identifiable dominant mass), and these had significantly worse OS (p=0.03). The most common pathologic diagnosis was pilocytic/pilomyxoid astrocytoma (n=92; 53%). DLGNT comprised a minority of cases (n=23, 14%), with a trend (p=0.056) towards worse survival compared to other diagnoses. The most frequent molecular alteration was BRAF fusion (78/151 with molecular testing; 52%), followed by FGFR mutations or fusions (18/151; 12%). BRAF V600E was underrepresented (14/151; 9%). 1p deletion was rare (17 patients) but highly associated with DLGNT. Methylation classification (n=70) was highly concordant with histologic diagnoses rather than clinical behavior. Importantly, patients who received upfront targeted therapies (TT; BRAF and/or MEK inhibition, n=9) had better PFS compared to those receiving chemotherapy (n=146, p=0.05). Furthermore, patients who were treated sequentially with chemo then TT had longer PFS on TT (p=0.011). This study presents the largest cohort of DLGG to date, expanding our understanding of the clinical, pathologic, and molecular features of this disease and supports the use of upfront targeted therapy.
LGG-13. UNRAVELING THE SPATIAL TUMOR MICROENVIRONMENT OF PEDIATRIC LOW-GRADE GLIOMAS USING IMAGING MASS CYTOMETRY
Authors: Faria Andrade* Augusto , Sigaud* Romain , Puligandla* Evan , Liu Bridget , Karimi Elham , Schmid Simone , Selt Florian , Driever Pablo Hernáiz , Koch Arend , Sahm Felix , Sievers Philipp , Pfister Stefan M , Witt Olaf , Jones David T W , Capper David , Walsh* Logan , Jabado* Nada , Milde* Till 
Published: June 2024

Abstract
Pediatric low-grade gliomas (pLGG) are the most common brain tumors in children and are associated with significant morbidity. Therefore, there is an urgent need for novel therapeutic strategies. While some studies have described pLGG’s tumor microenvironment (TME) from bulk RNAseq and scRNAseq, little is known about the spatial architecture of pLGG and its association with clinico-molecular features. Our study utilized imaging mass cytometry and a panel of 35 metal-labelled antibodies to unravel the spatial organization of key TME cell populations in 120 primary pLGG samples from the LOGGIC Core BioClinical DataBank. Cellular neighborhood analysis was performed to map the spatial organization of pLGG TME. Several clinic-molecular features (entity, tumor location, genetic driver alteration, disease progression status, age and sex) were used to measure their putative association with the enrichment of key cell populations and cellular structures to identify diagnosis and prognosis markers. Here, we identified a predominant presence of myeloid cells in the TME, particularly notable in optic pathway tumors, which exhibited unique immune profiles. Optic pathway tumors demonstrated elevated immune subsets, delineating distinct architectural features in the TME of this brain region. Spatial analysis defined cellular neighborhoods and specific interactions thereof, including myeloid interaction and macrophage-abundant regions. Clinically, these myeloid cell populations, associated with an increased expression of the immune checkpoint protein TIM3, suggesting the presence of an immuno-suppressive environment, were associated with inferior survival outcomes. Importantly, we identified an immunophenotype signature based on the presence of 4 myeloid cell populations significantly associated with progression free survival in our cohort. Our study underscored the need for accurate identification of immune cell populations influencing tumor progression, offering valuable insights for the identification of prognostic markers, and for the development of effective therapeutic strategies, such as immune checkpoint inhibitors, for the treatment of pLGG.
LGG-14. INTEGRATED MULTI-OMICS EXPLORATION OF MAPK PATHWAY INHIBITION IN PEDIATRIC PILOCYTIC ASTROCYTOMA
Authors: Sigaud Romain , Stefanski Anja , Selt Florian , Usta Diren , Kocher Daniela , Picard Daniel , Büdenbender Isabel , Remke Marc , Pfister Stefan M , Jones David T W , Brummer Tilman , Witt Olaf , Milde Till 
Published: June 2024

Abstract
Pilocytic astrocytomas (PA), the most common pediatric brain tumors, exhibit MAPK pathway alterations leading to its constitutive activation. They are also associated with low proliferation index due to the oncogene-induced senescence (OIS), sustained by senescence-associated secretory phenotype (SASP) factors. Little is known about the downstream consequences of MAPK activation leading to OIS-SASP, and of the molecular implications of MAPK pathway inhibition in senescent PA cells. Senescent DKFZ-BT66 cells derived from a primary KIAA::BRAF-fusion positive PA were used to generate RNA-sequencing and phospho-/proteomic datasets, before and after treatment with the MEK inhibitor (MEKi) trametinib for different time-spans. A multi-omics factor analysis tool (MEFISTO) and single sample gene set enrichment analysis (ssGSEA) were used to identify key OIS effectors and differentially regulated pathways upon MAPK inhibition. Trametinib treatment inhibited OIS and SASP signatures across all omics levels in the senescent DKFZ-BT66 cells, associated with reduced sensitivity towards senolytics drugs, indicating inhibition of senescence features upon MEKi. MEFISTO analysis identified key effectors involved in MAPK-induced OIS in the senescent PA cells. We built a pathway network using a prior knowledge network approach allowing to map the direct downstream effectors of MAPK leading to OIS-SASP. We identified several parallel pathways (JAK/STAT, p38, GSK3B) potentially involved in OIS and under the control of the MAPK pathway. In addition, ssGSEA showed that pathways related to upstream MAPK activators (SOS1, CK2, several RTKs) were predicted to be upregulated upon treatment, highlighting putative targets to be further investigated. Our data suggest that MAPKi reverses OIS signaling in senescent PA cells, while inducing the activation of MAPK upstream regulators, identifying putative co-targets for the treatment of PA. Further validation of the targetability of these pathways is pending. Furthermore, the identification of the MAPK-related OIS-SASP genes provides insight into the regulation of OIS-SASP by the MAPK pathway.