bluuebunny/crossref_metadata_2025_split huggingface dataset:
EXTH-60. CHARACTERIZATION OF THE ONCOLYTIC ADENOVIRUS DELTA-24-RGD AS THERAPEUTIC AGENT FOR THE TREATMENT OF THE PEDIATRIC EMBRYONAL BRAIN TUMORS AT/RT AND CNS-PNET
Authors: Garcia-Moure Marc , González-Huarriz Marisol , Laspidea Virginia , Marrodán Lucía , Gomez-Manzano Candelaria , Fueyo Juan , Patiño-García Ana , Alonso Marta M 
Published: December 2020

Abstract
Atypical teratoid/rhabdoid tumors (AT/RTs) and primitive neuroectodermal tumors of the central nervous system (CNS-PNET) are rare pediatric brain tumors affecting mainly infants and young children. Current therapies for these diseases are inefficient and often cause severe side effects; thus, new therapeutic strategies are urgently needed. Here, we evaluate the anti-tumor effect of the Delta-24-RGD oncolytic adenovirus in preclinical models of CNS-PNET and AT/RT. In vitro, the virus infects and efficiently replicates in different cell culture models of AT/RT and CNS-PNET, inducing a dose-dependent cytotoxic effect (IC50 values below 1 PFU/cell) and the release of immunogenic cell death stimuli. Survival studies in mice bearing orthotopic AT/RTs (supra and infratentorial) or CNS-PNETs demonstrate the therapeutic benefit of a single Delta-24-RGD intratumoral administration (107 or 108 PFU). In virus-treated mice, median overall survival increased between 50–300% (depending on the model), obtaining up to 60% of long-term survivors. Intra-ventricular injection of Delta-24-RGD hinders the development of secondary AT/RT spinal lesions. Moreover, response to the treatment was observed even delaying viral administration up to 30 days after tumor engraftment; thus, demonstrating therapeutic benefit even in animals challenged with large well-established tumor masses. The effect of the oncolytic virus was also assessed in an immunocompetent environment using hCD34+ humanized NSG-SGM3 mice. In this model, Delta-24-RGD significantly extended overall survival (from 23 to 24 days in AT/RT model and from 28 to 55 days in CNS-PNET) with no signs of toxicity associated with inflammation. Immunophenotyping of Delta-24-RGD treated tumors by flow cytometry, RNAseq and multiplexed histology revealed that Delta-24-RGD contributes to generate a pro-inflammatory status, allowing the infiltration of immune cells and the trigger of an antitumor immune response. In conclusion, these results demonstrate that Delta-24-RGD could be a feasible therapeutic choice for AT/RT and CNS-PNET, paving the way for upcoming clinical trials.
EXTH-64. SMALL GTPASES IN MENINGIOMAS: PROLIFERATION, MIGRATION, SURVIVAL, POTENTIAL TREATMENT AND INTERACTIONS
Authors: Kesseler Christoph , Kahr Julian , Waldt Natalie , Stroscher Nele , Liebig Josephine , Angenstein Frank , Kirches Elmar , Mawrin Christian 
Published: December 2020

Abstract

PURPOSE
To evaluate the role of the small GTPases RhoA, Rac1 and Cdc42 in meningiomas as therapeutic targets and their interactions in meningiomas.

EXPERIMENTAL DESIGN
We analyzed expression of GTPases in human meningioma samples and meningioma cell lines of various WHO grades. Malignant IOMM-Lee meningioma cells were used to generate shRNA mediated knockdowns of GTPases RhoA, Rac1 or Cdc42 and to study knockdown effects on proliferation and migration, as well as analysis of cell morphology by confocal microscopy. The same tests were used to investigate effects of the two inhibitors Fasudil and EHT-1864 of malignant IOMM-Lee, KT21 and benign Ben-Men cells and the effects of these drugs on IOMM-Lee knockdown cells. The effects of GTPase knockdowns and Fasudil treatment were studied in terms of overall survival by intracranial xenografts of mice. Potential interactions of GTPases regarding NF2, mTOR and FAK-Paxillin were examined.

RESULTS
Small GTPases were upregulated in meningiomas of higher tumor grades. Reduced proliferation and migration could be achieved by GTPase knockdown in IOMM-Lee cells. Additionally, the ROCK-inhibitor Fasudil and Rac1-inhibitor EHT-1864 reduced proliferation in different meningioma cell lines and reduced proliferation and migration independent of GTPase knockdowns/status. Moreover, overall survival in vivo could also be increased by knockdowns of RhoA and Rac1 as well as Fasudil treatment. GTPase expression was affected dependent on the NF2 status but effects were not very distinct, indicating that NF2 is not strongly involved in GTPase regulation in meningiomas. In terms of mTOR and FAK-Paxillin signaling, each GTPase changes those pathways in a different manner.

CONCLUSION
Small GTPases are important effectors in meningioma proliferation and migration in vitro as well as survival in vivo and their inhibition should be considered as potential treatment option.
EXTH-65. USING METHYLATION PROFILES TO GUIDE THE REPURPOSING OF CHEMOTHERAPIES AGAINST HIGH-RISK MENINGIOMAS
Authors: Tran Anh , Scholtens Denise , Zhang Lyndsee , Pokorny Jenny , Baran Aneta , Sahm Felix , Aldape Kenneth , James Charles , Horbinski Craig 
Published: December 2020

Abstract
Meningioma is the most common primary brain tumor with nearly thirty thousand new cases in the US every year. While most meningiomas grow slowly, hence categorized as benign, they can still impact brain structures and result in disability or lethality. Currently, there is no widely accepted chemotherapy for meningioma, and our understanding of the disease’s molecular characteristics is very limited. In this study, we aimed to identify druggable molecular targets for repurposing of chemotherapies against meningiomas. We analyzed previously published dataset of 493 meningioma patients by Felix Sahm et al (Lancet Oncology, 2017) for association with progression-free survival (PFS) and identified associations of methylation at individual CpG sites as detected by the Illumina 450k platform with PFS. Subsequently, we searched for candidate drugs targeting the pathways linked to poor patient prognosis. Our analyses indicated 981 genes for which methylation of mapped CpG sites was found to be consistently associated with shorter PFS (positive hazard ratios (HRs)) and with longer PFS (negative HRs) at FDR-adjusted p &lt; 0.05. Using Cytoscape/Reactome FI app, we cross-referenced current cancer drugs that target these and identified docetaxel and raloxifene hydrochloride as potential candidates. In our vitro study, docetaxel caused apoptotic cell death in established and primary patient meningioma lines of various grades. IC50s of docetaxel in the sixteen meningioma cell lines tested ranged from 0.8nM to 4.4mM, which partially corresponded to the growth rates of these cells. Our study will advance our understanding of molecular pathways driving meningioma and identify potential targeted therapies to bridge the current gap in treatment of the disease.
EXTH-68. STUDY THE SYNERGISTIC EFFECT OF FOCUSED ULTRASOUND AND RADIATION THERAPY FOR BRAIN TUMOR TREATMENT
Authors: Huang Chiungyin , Wei Kuochen 
Published: December 2020

Abstract
The standard treatment of malignant brain tumor is surgical resection followed by adjuvant chemo/radiotherapy. However, in spite of these aggressive treatments, tumor may still recur and resulting in poor survival. In solid tumors, the hypoxia condition presented in most of tumor area may contribute to treatment failure in both adjuvant therapies. It had been proven that systemic delivered oxygen may not sufficient for ionizing radiation to produce cytotoxic effect. A recent study reported using focused ultrasound combined with oxygen-contained microbubbles prior to radiation significantly increased the oxygen content in breast cancers and statistically improved animal survival. Therefore, providing sufficient oxygen in tumor area may be beneficial for radiation therapy. To study the potential role of such strategy for brain tumor treatment, we used focused ultrasound to treat brain tumor bearing animals before radiation therapy. As compared with non-ultrasound treatment groups, the tumor growth rate was significantly inhibited, and the animal survival is prolonged. We also analysis the gene expression changes, reveal some potential pathway that may involve in the process. Furthermore, we found focused ultrasound combined with non-oxygen-containing microbubbles also represented similar results, demonstrate the focused ultrasound induced cerebral vascular permeability increment may also contribute to the radiation therapy effect for brain tumor treatment.
EXTH-77. ONC201 EXHIBITS PASSIVE DIFFUSION AND BROAD DISTRIBUTION IN THE CENTRAL NERVOUS SYSTEM
Authors: Morrow Sara , Prabhu Varun , Tarapore Rohinton S , Theerman Gina , Lake Leah , Guo Ailan , Stogniew Martin , Allen Joshua 
Published: December 2020

Abstract
Imipridone ONC201 is an investigational agent in phase II clinical trials for H3 K27M-mutant diffuse midline glioma with evidence of durable objective responses and clinical symptom improvements as a single agent. The systemic pharmacokinetics of ONC201 and its ability to achieve target concentrations in supratentorial glioblastoma have been demonstrated in clinical trials; however, its clearance and distribution in midline structures and other areas of the central nervous system (CNS) haven’t been evaluated. A quantitative whole-body autoradiography study was conducted in Long-Evans rats with a single dose of [14C]-ONC201. [14C]-ONC201-related material was rapidly distributed throughout the body, with concentrations peaking at 1h for most tissues. The endocrine, metabolic/excretory, ocular and gastrointestinal tract tissues contained the highest distribution of [14C]-ONC201-derived radioactivity. Importantly, [14C]-ONC201 material was distributed evenly across brain substructures, including the meninges and midline structures of the brain; all tissues had a half-life of 1.4–7.9h, with the exception of the meninges (2397.3h). Given the uniform distribution throughout the CNS, we evaluated the permeability and efflux potential of ONC201 in bidirectional transport assays using human Caco-2 cell monolayers. ONC201 displayed high permeability in the apical to basolateral direction with apparent permeability values of 23–31×10–6 cm/s at 7–700μM. In the basolateral to apical direction, apparent permeability values were 11–24 × 10–6 cm/s. The efflux ratio values were 0.46–0.79 for ONC201, suggesting that ONC201 is not a substrate of efflux transporters. However, ONC201 exerted inhibitory potential on MDR1- (90.6%) and BCRP-mediated (81.6%) transport at 200mM. In summary, ONC201 exhibits passive diffusion without being effluxed, which may enable its rapid and wide distribution throughout the CNS. This distribution profile suggests that the compound may achieve therapeutic concentrations throughout the CNS with oral administration and that investigation of additional CNS tumors will not be hindered by drug delivery to specific anatomic structures.
IMMU-03. EFFECT OF COMBINING IRRADIATION AND ANTI-CD47 TREATMENT ON THE PHAGOCYTOSIS OF NORMAL BRAIN CELLS
Authors: Hamrick Forrest , Youssef Osama , Cheshier Samuel 
Published: December 2020

Abstract
Immunotherapy using CD47 blockade has shown promise in treating adult and pediatric malignant primary central nervous system tumors. We recently demonstrated that irradiation significantly enhanced anti-CD47-dependent phagocytosis of high-grade glioma cells in vitro. Furthermore, mice engrafted with high-grade human glioma that received anti-CD47 combined with irradiation showed a significant increase in the survival rate and a significant decrease in tumor growth than those that received a single treatment. However, the use of irradiation may result in potential toxicity to normal CNS cells that are not susceptible to macrophage phagocytosis in anti-CD47 monotherapy. We have now extended these studies to test the effect of combining anti-CD47 and irradiation on macrophage-mediated phagocytosis of central nervous system cells. We analyzed phagocytosis of normal human neural stem cells exposed to different irradiation doses in combination with anti-CD47 treatment to assess for the potential toxicity that uniquely exists with this treatment combination.
IMMU-18. INTERPLAY BETWEEN IDH1 AND ATRX MUTATIONS GOVERN INNATE IMMUNE RESPONSES IN GLIOMAS
Authors: Hariharan Seethalakshmi , Bowie Michelle , Hostettler Janell , Roso Kristen , He Yiping , Roskoski Martin A , Charbonneau Casey , Keir Stephen , Brown Michael , Irvin David , Zhang Gao , Gromeier Matthias , Huse Jason , Ashley David 
Published: December 2020

Abstract
Innate-based immunotherapies are becoming increasingly important for treating brain tumor patients. About 50% of WHO grade II and III gliomas carry mutations in IDH1 and ATRX genes. Mutant IDH1 results in the production of 2-hydroxyglutarate, an oncometabolite that promotes global metabolic and epigenetic alterations. ATRX is a SWI-SNF chromatin remodeling protein that is involved in cell cycle regulation and maintenance of genomic stability. Both IDH1 and ATRX mutations have been implicated in dysfunctional immune signaling in cancer cells. However, the interplay between these mutations in mediating innate immune responses has not been investigated in gliomas. We have derived human and mouse glioma cell lines carrying mutations in IDH1 (IDH1R132H) and/or ATRX, which we then used to generate both immune competent and nude mice models. Treating the ATRX knockout (KO) cell lines with dsRNA-based innate stimuli led to an early induction in phospho-IRF3, and late induction in phospho-STAT1 and ISG15, suggesting that ATRX deletion may enable a potent activation of type I interferon production and sensitize glioma cells to dsRNA-based innate stimuli. Our syngeneic murine glioma models confirm a survival advantage for mice carrying ATRX-KO tumors. These tumors also exhibit enhanced infiltration of T-cells and expression of activated macrophage markers. On the other hand, presence of IDH1R132H led to a suppression in baseline expression of key innate immune players, which could be rescued by the mutant IDH1 inhibitor, BAY-1436032. Cells harboring IDH1R132H and ATRX-KO retained sensitivity to dsRNA indicating that IDH1R132H does not dampen the ATRX KO-mediated sensitivity to dsRNA. Our models are under evaluation with a combination of BAY-1436032 and clinically relevant dsRNA-based innate therapies. Our data indicates the presence of an interplay between IDH1 and ATRX mutations that may regulate innate signaling in gliomas. Understanding the mechanisms governing this interplay may aid in designing therapies that exploit this interplay.
IMMU-21. THE COMBINATION OF DELTA-24-ACT WITH AN IMMUNE CHECKPOINT INHIBITOR RESULTS IN ANTI-GLIOMA EFFECT AND IMMUNE MEMORY
Authors: Puigdelloses Montserrat , Laspidea Virginia , Garcia-Moure Marc , De la Nava Daniel , Hambardzumyan Dolores , Chen Zhihong , Labiano Sara , Fueyo Juan , Gomez-Manzano Candelaria , de Larraya Jaime Gállego-pérez , M Alonso Marta 
Published: December 2020

Abstract
Oncolytic viruses have become promising therapeutic candidates to treat gliomas. Our group has developed Delta-24-ACT, an oncolytic adenovirus armed with the positive costimulatory ligand 4-1BBL which is capable to trigger the activation of T cells and thereby increase their antitumor immune response. Here we evaluate the anti-glioma effect of Delta-24-ACT alone or in combination with an immune checkpoint inhibitor. We observed that Delta-24-ACT was able to infect and kill murine glioma (GL261-5 and CT-2A) and also human glioma cell lines (U87-MG and U251-MG), while maintaining its replication in the latter. Of importance, Delta-24-ACT infection resulted in 4-1BBL expression on the membrane of glioma cells. Moreover, this ligand was functional and was able to stimulate CD8 lymphocytes in vitro, suggesting the potential of Delta-24-ACT to trigger an effective immune response. Furthermore, in vivo Delta-24-ACT showed anti-tumour effect in two murine glioma models by significantly increasing the median survival time and leading to long-term survivors. Mechanistic studies demonstrated an increase of the T cell infiltration and the activation of different immune cell populations by flow cytometry and a decrease of proliferative cells and tumour vessels by immunohistochemistry on FFPE brain samples. Importantly, the infiltrating lymphocytes also showed signs of exhaustion increasing the amount of IL-10 and the expression of PD-1. To overcome this exhaustion we combined Delta-24-ACT with an anti-PD-1 antibody. Evaluation of this combination in vivo further increased the median survival time of treated tumor-bearing mice and resulted in 50% long-term survivors. Rechallenge studies with the same cell line showed that combination treatment effectively protected these animals of developing tumors and therefore, the acquisition of immune memory. In summary, our data demonstrated that Delta-24-ACT induces a potent anti-tumour effect in vitro and in vivo as a result of the recruitment of immune cell populations modulating the immunosuppressive tumour microenvironment of glioma.
IMMU-23. CLINICAL AND IMMUNOLOGICAL CHARACTERIZATION OF IMMUNE CHECKPOINT MOLECULE LIGHT IN HUMAN GLIOMAS
Authors: Han Mingzhi , Li Xingang 
Published: December 2020

Abstract

BACKGROUND
Dysregulation of immune checkpoint molecules leads to immune evasion in human tumors but has become a viable target for tumor therapy. Here, we examined expression of LIGHT (TNFSF14), an immune checkpoint molecule, in human glioblastoma (GBM) to assess its potential as a molecular target for treatment.

METHODS
Molecular and clinical data from publicly available genomic databases containing WHO grade II-IV human glioma cases were analyzed. Immunohistochemistry was applied to assess LIGHT protein levels in primary tumor sections. Statistical analysis was performed using Matlab and R language.

FINDINGS
LIGHT was found to be elevated in aggressive gliomas, particularly in the mesenchymal molecular subtype and isocitrate dehydrogenase (IDH) wild-type GBM. LIGHT exhibited potential as a prognostic marker based on Cox regression and nomogram models. LIGHT displayed intra-tumor heterogeneity and was more highly expressed in peri-necrotic and microvascular regions. Gene ontology and pathway analysis revealed enrichment of LIGHT in multiple immune regulatory processes. Finally, in cell lineage analysis, LIGHT was found to be tightly associated with several infiltrating immune and stromal cell types which localized to the tumor microenvironment.

INTERPRETATION
Our data highlights the importance of LIGHT in the development of GBM and as a potential molecular target in combination with current immune checkpoint blockades for treatment of GBM.
IMMU-28. INDUCTION OF TERTIARY LYMPHOID STRUCTURE-LIKE T-CELL CLUSTERS BY DELIVERY OF A NOVEL GENE COMBINATION INTO AN IMMUNOCOMPETENT MOUSE MODEL OF GLIOBLASTOMA
Authors: Downey Kira , Hegde Bindu , Chheda Zinal , Zhang Jason , Okada Hideho 
Published: December 2020

Abstract
The lack of conventional lymphatic drainage to and from the brain parenchyma restricts the capacity of the peripheral immune system to recognize and respond to glioma antigens. In some peripheral solid tumor types and central nervous system autoimmunity, the spontaneous development of tertiary lymphoid structures (TLS) with varying degrees of organization have been observed in human patients and mice following chronic inflammation. In the cancer setting, presence of TLS are generally associated with improved prognosis, especially when they are characterized by intratumoral infiltration of CD8+ T-cells. We aimed to induce the development of TLS in vivo, utilizing our SB28 glioblastoma model which is sparsely infiltrated by lymphocytes. As a proof-of-concept study, we stably transduced SB28 with a combination of several TLS-stimulating factors that we’ve identified and injected these cells into the brain parenchyma of syngeneic C57BL/6J mice. A combination of the chemoattractant and lymphoid follicle-stimulating cytokines LIGHT, CCL21, IL-7, and IL-17 produced substantial infiltration of CD8+CD3+ T-cells into the tumor and nearby parenchyma. However, this combination was also associated with accelerated tumor growth. A modified gene combination including LIGHT, CCL21, and IL-7 promoted CD8+CD3+ T-cell infiltration by flow cytometry, T-cell clustering by immunofluorescence analysis, and inhibited tumor burden compared with the control as measured by bioluminescent imaging. There was also evidence of increased lymphatic vasculature around the margins of T-cell clustering as demonstrated by LYVE-1 staining. Together, these analyses highlight a role for these factors in stimulating the recruitment and clustering of T-cell to the glioblastoma microenvironment in a TLS-like phenomenon. Future studies will evaluate whether the recruitment of other lymphocytes and stromal cells to these TLS-like clusters can promote T-cell memory and persistence. Ultimately, we aim to provide these factors utilizing a gene delivery method that will prove translatable to the clinic and complementary to existing T-cell therapies.
IMMU-41. HIGH-THROUGHPUT RETRIEVAL OF THERAPEUTIC T CELL RECEPTORS FROM GLIOMA
Authors: Lindner Katharina , Tan Chin Leng , Bozza Matthias , Sanghvi Khwab , Poschke Isabel , Harbottle Richard , von Deimling Andreas , Wick Wolfgang , Sahm Felix , Platten Michael , Green Edward W , Bunse Lukas 
Published: December 2020

Abstract
Gliomas are tumors with low mutational burden with the majority of them being resistant to checkpoint inhibition due to few immunogenic antigens. Multicenter vaccine trials targeting personalized neoantigens in gliomas demonstrated feasibility and illustrated the challenges of retrieving neoepitope-specific T cells based on the prediction of immunogenic neoepitopes. Here we took an entirely different T cell-centric approach and established a single cell sequencing-based high-throughput T cell receptor (TCR) retrieval platform, exploiting the therapeutic potential of spontaneous intratumoral T cell clonotypes for the development of adoptive cell therapy. We conducted direct ex vivo TCR single cell sequencing from freshly sorted human glioma-infiltrating T cell samples. High fidelity PCR was established to clone TCRs from single cell libraries directly into episomal expression vectors further optimized for T cell therapy. In parallel to standard therapy, patient-derived xenografts were developed and characterized. Tumor-reactivity of retrieved TCRs was demonstrated against patient-derived cell lines. Collectively, we provide a novel sequencing-based platform for high-throughput identification and validation of endogenous glioma-targeting TCRs and demonstrate their therapeutic applicability.