bluuebunny/crossref_metadata_2025 huggingface dataset:
EXTH-26. SECONDARY STRUCTURE ANALYSIS OF THE EGFR PRE-mRNA TRANSCRIPT TO IDENTIFY TARGETABLE REGIONS AND OPTIMIZE RNA THERAPY
Authors: Hicks Martin , Fink Ryan , Gawargi Flobater
Published: December 2020

Individuals diagnosed with glioblastoma multiforme (GBM) have a short life expectancy of 12–15 months. Current strategies are often limited by the blood-brain barrier. This project is to develop therapies to bypass challenges to effective and continuous drug delivery to the brain, targeting cancer-driving genes. Epidermal growth factor receptor (EGFR) is dysregulated in 57% of all GBM. Our approach uses an adeno-associated virus gene transfer vector encoding RNA therapeutics targeting critical elements of the EGFR pre-mRNA transcript. The ‘pre-mRNA structurome’ can be used to uncover and determine the accessibility of targetable regions. Our approach has the potential to deliver one single dose of gene therapy directly to the GBM tumor environment and block the production of EGFR and activate the expression of a stable therapeutic isoform of EGFR. To advance our therapeutic strategy, we have analyzed the EGFR secondary structure using selective 2’ hydroxyl acylation and primer extension followed by mutational profiling (SHAPE-MaP). SHAPE-MaP reactivity profiles were generated revealing the structure of splicing and cryptic polyadenylation signal (PAS) elements within the targeted region. We identified enhancer binding motifs surrounding the 5’ splice site and hidden elements of the cryptic PAS. Based on these structural profiles, we generated RNA therapies to unravel the hidden PAS to activate expression of the short therapeutic isoform.
EXTH-48. BMP4 BINDING PEPTIDE AMPHIPHILE NANOFIBERS FOR THE TREATMENT OF PEDIATRIC HIGH-GRADE GLIOMAS
Authors: Smith Cara , Nayak Sonali , Mahenthiran Ashorne , Wang Yufen , Fyrner Timmy , McClendon Mark , Mania-Farnell Barbara , Kessler John , Tomita Tadanori , James Charles , Stupp Samuel , XI Guifa
Published: December 2020

Pediatric high-grade glioma (pHGG) is among the most formidable cancers occurring in childhood. Bone morphogenetic protein 4 (BMP4) reduces the number of glioma stem-like cells and induces apoptosis. Treating tumors with exogenous BMP4 could prove effective in treating gliomas. However, a short half-life limits its clinical application. Glycosylated peptide amphiphile (GlycoPA), with a design inspired by heparin’s natural ability to bind growth factors including BMP4 through non-covalent interactions, was previously characterized and found to form high-aspect ratio supramolecular nanofibers that present growth-factor binding sulfated monosaccharides on their surface. These supramolecular nanofibers could carry excessive amounts of growth factor and markedly enhance their biological function. In this study, we verified that GlycoPA is able to bind BMP4 and dramatically increase its half-life with an ELISA assay. We also show that GlycoPA-BMP4, in comparison to free BMP4, significantly decreases pHGG cells’ proliferation in vitro. Initial in vivo intracranial distribution experimental results showed that GlycoPA has a superior normal brain distribution in comparison to a control PA (E2 PA) that has the same base structure as GlycoPA except with no glycosylated group. Preliminary results show that GlycoPA-BMP4 markedly decreases pediatric glioma tumor growth in comparison to free BMP4. Our combined in vitro and in vivo results demonstrate PA supramolecular nanofibers as an innovative and promising BMP4 delivery platform for clinical application in the treatment of brain tumors. Our future directions will investigate the therapeutic efficacy of GlycoPA-BMP4 in pediatric HGG through testing large numbers of animals and introducing first-line clinical chemotherapy drugs in combination and in various consequence.
EXTH-51. ANTI-INVASIVE EFFICACY AND SURVIVAL BENEFIT OF THE YAP-TEAD INHIBITOR VERTEPORFIN IN PRECLINICAL GLIOBLASTOMA MODELS
Authors: Barrette Anne Marie , Bouras Alexandros , Nudelman German , Mussa Zarmeen , Zaslavsky Elena , Hadjipanayis Constantinos , Birtwistle Marc , Tsankova Nadejda
Published: December 2020

Glioblastoma (GBM) remains an incurable disease, in large part due to its malignant infiltrative spread, and current clinical therapy fails to target the invasive nature of tumor cells in disease progression and recurrence. Here, we use the YAP-TEAD inhibitor Verteporfin to target a convergence point for regulating tumor invasion/metastasis and establish the robust anti-invasive therapeutic efficacy of this FDA-approved drug and its survival benefit across several preclinical glioma models. Using patient-derived GBM cells and orthotopic xenograft models (PDX), we show that Verteporfin treatment disrupts YAP/TAZ-TEAD activity and processes related to cell adhesion, migration and epithelial-mesenchymal transition. In-vitro, Verteporfin impairs tumor migration, invasion and motility dynamics. In-vivo, intraperitoneal administration of Verteporfin in mice with orthotopic PDX tumors shows consistent drug accumulation within the brain and decreased infiltrative tumor burden, across three independent experiments. Interestingly, PDX tumors with impaired invasion after Verteporfin treatment downregulate CDH2 and ITGB1 adhesion protein levels within the tumor microenvironment. Finally, Verteporfin treatment confers survival benefit in two independent PDX models: as monotherapy in de-novo GBM and in combination with standard-of-care chemoradiation in recurrent GBM. These findings indicate potential therapeutic value of this FDA-approved drug if repurposed for GBM patients.
EXTH-59. POTENT, SELECTIVE, AND BRAIN PENETRANT INHIBITORS OF EXTRACELLULAR DOMAIN EGFR ONCOGENIC MUTANTS EXPRESSED IN GBM DEMONSTRATE EFFICACY IN AN INTRACRANIAL PATIENT DERIVED XENOGRAFT MODEL
Authors: O’Connor Matthew , Lucas Matt , Romashko Darlene , Rasmussen Sara , Fiorenza Raffaele , Lin Tai-An , Waters Nigel , Trainor George , Flohr Alexander , Ottaviani Giorgio , Roberts Christopher , Buck Elizabeth , Nicolaides Theodore , Raleigh David , Ozawa Tomoko , Arista Luca
Published: December 2020

EGFR mutations identified in glioblastomas (GBM) occur nearly exclusively at the allosteric extracellular domain (ECD) and constitutively activate oncogenic signaling. Despite wide success in treating tumors expressing EGFR catalytic site mutants, no drug has demonstrated clinical utility against tumors expressing the extracellular domain EGFR mutants. We demonstrate that the family of ECD mutations are not only co-expressed in GBM, but that they all activate the oncogene through a similar disulfide bond-mediated receptor dimerization mechanism. This dimerization occurs independent of ligands and renders the Locked-dimer (LoDi)-EGFR insensitive to agents that target the EGFR kinase domain mutants in NSCLC. The kinase conformation induced by these ECD mutations seen in glioblastomas is both oncogenic and altered from kinase domain mutations, thus necessitating a new approach to targeting. By screening against cells expressing LoDi-EGFR mutants, we have identified the first inhibitors that potently and selectively target LoDi-EGFR mutants versus both canonical active site oncogenic mutants and wild type EGFR. Through an optimization effort, we have identified a novel family of potent and selective LoDi-EGFR mutant inhibitors that effectively penetrate the blood brain barrier (BBB) following oral dosing in preclinical studies. A leading exemplar, BDTX-GBM-001, inhibits the 5 major LoDi-EGFR mutants expressed in GBM with antiproliferative potency of ~10 nM while showing favorable selectivity versus the human kinome. When dosed orally in the intracranial GBM6 patient derived xenograft model at 50, 30, and 15 mg/kg, a dose responsive decrease in tumor growth, as well as a statistically significant increase in survival, were observed. These data support the continued evaluation of rationally designed BBB penetrant inhibitors selectively targeting the common LoDi-EGFR mutants and enable the first chance to fully test the clinical hypothesis of EGFR driver mutants in GBM.
EXTH-61. COMBINATION OF DISULFIRAM AND COPPER INDUCES NPL4 AGGREGATION, TARGETS CD133-NESTIN CELLS AND EXTENDS SURVIVAL IN MEDULLOBLASTOMA GROUP 3 MODELS
Authors: Serra Riccardo , Zhao Tianna , Huq Sakibul , Gorelick Noah , Casaos Joshua , Cecia Arba , Mangraviti Antonella , Olivi Alessandro , Brem Henry , Jackson Eric M , Tyler Betty
Published: December 2020

BACKGROUND

Medulloblastoma (MB), the most common brain malignancy among children, is classified into four molecular subtypes, WNT-driven, Shh-driven, Group 3 and 4. The aim of this study was to assess the effects of the combination of Disulfiram, an inhibitor of Aldehyde Dehydrogenase, and Copper in Shh-driven and Group 3 MB, in vitro and in vivo.

METHODS

The mechanisms of action and anti-cancer stem-cell effects of disulfiram were evaluated with clonogenic assays, flow-cytometry (FC), western blotting (WB), and immunofluorescence (IF) using established MB cell-lines - ONS76, UW228, D425med, D341 and D283- representing the main molecular subtypes. Survival, tumor volume, nuclear protein localization protein-4-expression (NPL4) and markers of proliferation/apoptosis were assessed in multiple models of Group 3 MB in vivo and ex vivo with WB and immunohistochemistry (IHC).

RESULTS

Significant in vitro cytotoxicity was demonstrated at nanomolar concentrations of DSF in all lines. DSF/Cu++ induced cell death (increased AnnV/PI, cleaved-Poly(ADP-ribose)polymerase fraction, and Apoptosis Inducing Factor on WB/FC/IF, in vitro and ex vivo) through NPL4 accumulation in cell nucleus and intracellular buildup of poly-ubiquitylated proteins. DNA damage was also detected with WB and H2AX foci on immunofluorescence. Flow-cytometry analysis demonstrated a significant reduction in ALDH, Nestin- and CD133-positive cells in Group 3 lines, confirmed with WB in vitro and ex vivo. DSF/Cu++-toxicity was tested in vivo in multiple dose-escalating trials, and the combination significantly prolonged survival and reduced tumor volume in D425 and D341 xenografts. IHC showed lower Ki67 and increased Cleaved-Caspase-3 expression, higher NPL4-positive cells and no difference in NeuN and GFAP-positive cells after treatment.

CONCLUSIONS

DSF/Cu++ demonstrated a potent therapeutic effect on Shh-driven and Group 3 MB cell lines by determining apoptosis, targeting cancer stem cells and inducing DNA damage. Our data suggest that this combination may serve as a novel treatment, alone or with existing therapies, for pediatric MB.
EXTH-71. CYTOSTATIC HYPOTHERMIA FOR GLIOBLASTOMA
Authors: Faaiz Enam Syed , Huang Jianxi , Kilic Cem , Tribble Connor , Betancur Martha , Blocker Stephanie , Owen Steven , Bellamkonda Ravi
Published: December 2020

As a cancer therapy, hypothermia has been used at sub-zero temperatures to cryosurgically ablate tumors. However, these temperatures can indiscriminately damage both tumorous and healthy cells. Additionally, strategies designed to kill tumor typically accelerate their evolution and recurrence can be inevitable in cancers such as glioblastoma (GBM). To bypass these limitations, here we studied the use of hypothermia as a cytostatic tool against cancer and deployed it against an aggressive rodent model of GBM. To identify the minimal dosage of ‘cytostatic hypothermia’, we cultured at least 4 GBM lines at 4 continuous or intermittent degrees of hypothermia and evaluated their growth rates through a custom imaging-based assay. This revealed cell-specific sensitivities to hypothermia. Subsequently, we examined the effects of cytostatic hypothermia on these cells by a cursory study of their cell-cycle, energy metabolism, and protein synthesis. Next, we investigated the use of cytostatic hypothermia as an adjuvant to chemotherapy and CAR T immunotherapy. Our studies demonstrated that cytostatic hypothermia did not interfere with Temozolomide in vitro and may have been synergistic against at least 1 GBM line. Interestingly, we also demonstrated that CAR T immunotherapy can function under cytostatic hypothermia. To assess the efficacy of hypothermia in vivo, we report the design of an implantable device to focally administer cytostatic hypothermia in an aggressive rodent model of F98 GBM. Cytostatic hypothermia significantly doubled the median survival of tumor-bearing rats with no obvious signs of distress. The absence of gross behavioral alterations is in concurrence with literature suggesting the brain is naturally resilient to focal hypothermia. Based on these findings, we anticipate that focally administered cytostatic hypothermia alone has the potential to delay tumor recurrence or increase progression-free survival in patients. Additionally, it could also provide more time to evaluate concomitant, curative cytotoxic treatments.
IMMU-01. SINGLE CELL SEQUENCING OF MELANOMA BRAIN METASTASES UNVEILS HETEROGENEITY OF THE TUMOR MICROENVIRONMENT IN RESPONSE TO IMMUNE CHECKPOINT BLOCKADE
Authors: Alvarez-Breckenridge Christopher , Markson Samuel , Stocking Jackson , Lastrapes Matt , Nayyar Naema , Bertalan Mia , Kaplan Alexander , Alvarez Maria Martinez-Lage , Izar Benjamin , Suva Mario , Sullivan Ryan , Cahill Daniel , Carter Scott , Brastianos Priscilla
Published: December 2020

Immune checkpoint inhibitors (ICI) have revolutionized oncologic treatment for metastatic melanoma. With improved systemic control, there has been increasing prevalence of patients with brain metastases. Recent evidence has demonstrated intracranial responses in a subset of these patients treated with ICI. We hypothesize that the response to ICI in melanoma brain metastases (MBM) is reflective of unique features within the tumor microenvironment of the brain. A cohort of 27 patients, encompassing 8 pre- and 19 post-immunotherapy MBM underwent single cell RNA sequencing (Smart-Seq2). The cohort includes patients with longitudinal cranial resections and simultaneously resected, spatially distinct tumors. Each tumor underwent unsupervised transcriptomic analysis, differential gene expression, inferred copy number variation, and T-cell receptor (TCR) clonotyping. Published extracranial melanoma single cell datasets were used to compare the tumor microenvironment of the brain and periphery in response to ICI. A total of 14,027 cells (6,189 malignant, 7,838 non-malignant) were sequenced. Brain metastases demonstrated a heterogeneous distribution of macrophage states. Intracranial macrophages were found to be more tumor-supportive than their extracranial counterparts. MBM also included a distribution of reactive neutrophils and astrocytes. Analysis across pre- and post-treatment MBM demonstrated an increase in clonally expanded T cells in patients responding to ICI. Across longitudinal brain metastases collected from the same patients, there was evidence of identical T cell clones across timepoints and locations. Single cell sequencing of MBM provides insights into the cellular composition of the tumor and microenvironment. Our data suggest the cellular heterogeneity within MBM is unique when compared to extracranial disease. Additionally, T cell clonal expansion is found following ICI and T cells of the same clonotype infiltrate spatially and temporally separated brain metastases. These findings raise potential therapeutic implications as we learn to target the differential features of the innate and adaptive immune system within brain metastases and their extracranial counterparts.
IMMU-15. HEPARIN INHIBITS THE EXTRACELLULAR VESICLE-MEDIATED INDUCTION OF IMMUNOSUPPRESSIVE MONOCYTES IN GLIOBLASTOMA
Authors: Himes Benjamin , Fain Cori , Tritz Zachariah , Li Helen , Geiger Philipp , Peterson Timothy , Parney Ian
Published: December 2020

Glioblastoma (GBM) is the most common and fatal primary brain tumor in adults. The development of novel therapies is critical, as little has changed regarding the standard of care in nearly two decades. Immunotherapy holds much promise, as treatments including chimeric antigen receptor (CAR) T cells and immune checkpoint blockade inhibitors have transformed the treatment of a number of cancers in recent years. However, GBM patients exhibit profound immunosuppression, limiting the efficacy of these therapies. Understanding the mechanisms of GBM-mediated immunosuppression is critical to overcoming this barrier. GBM-derived extracellular vesicles (EVs) have been shown to mediate the induction of immunosuppressive monocytes, which may point to a mechanism of immunosuppression. EVs make initial contact with target cells through interactions between heparan sulfate proteoglycans, and soluble heparin has been shown to inhibit these interactions in some models. We demonstrate that soluble heparin inhibits the binding of GBM-derived EVs to monocytes in a dose-dependent manner, and that heparin treatment reduces the induction of immunosuppressive monocytes upon in vitro conditioning of monocytes with GBM-derived EVs (p< 0.01). Further, we demonstrate that heparin treated EV-conditioned monocytes are functionally less immunosuppressive than untreated EV-conditioned monocytes as measured by T cell proliferation in co-culture studies (p< 0.05). Taken together, these findings underscore the import of tumor-derived EVs in immunosuppression in GBM, and demonstrate the feasibility of targeting EV-monocyte interactions in treating GBM-mediated immunosuppression.
IMMU-22. EARLY RELEASE OF TYPE I INTERFERON DRIVES BRAIN CANCER IMMUNOGENICITY AND RESPONSE TO IMMUNOTHERAPY
Authors: Wummer Brandon , Qdaisat Sadeem , Grippin Adam , Karachi Aida , Weidert Frances , Huang Jianping , Rahman Maryam , Mitchell Duane , Mendez-Gomez Hector , Sayour Elias
Published: December 2020

BACKGROUND

Molecular drivers of cancer immunogenicity in brain tumors are still being unraveled. While BATF3 expression, STING, and interferon response factors (IRFs) are necessary for cancer immunogenicity, the presence of type I interferon (IFN-I) is contextual having been reported to elicit both anti-tumoral and pro-tumoral effects. A better understanding of IFN-I signaling mechanisms is necessary to elucidate drivers of brain cancer immunogenicity and resistance.

OBJECTIVE

We sought to assess the role of IFN-I signaling in brain tumor immunogenicity and response to immune checkpoint inhibitors (ICIs) in ICI sensitive brain tumor models (i.e. GL261). We then sought to develop strategies to reset IFN-I signaling in ICI resistant brain tumor models (i.e. KR158b).

METHODS

To reset IFN-I signaling in immunologically ‘cold’ tumors unresponsive to ICIs, we developed lipid-nanoparticles (NPs) to deliver mRNA payloads to the brain tumor microenvironment (TME).

RESULTS

In immune-sensitive GL261 tumors, we showed that early release of IFN-I unlocks cancer immunogenicity and ICI response. Blockade of IFN-I during tumorigenesis (within 24h, but not days later) increases tumorigenicity and abrogates ICI activity in sensitive tumors. In ICI resistant KR158b tumors, we show that systemic administration of tumor-derived RNA-NPs localize to myeloid cells within the TME for simultaneous activation of multiple innate pathways including BATF3 (necessary for effector DCs), IRF5 (necessary for M2 to M1 macrophage reprograming), and IRF7 (necessary for IFN-I production). These RNA-NPs induce near-immediate release of IFN-I (within hours), reprogram the brain TME in an IFNAR1 (IFN-I receptor) dependent manner, and elicit significant anti-KR158b efficacy as a monotherapy. Following IFNAR1 blockade, RNA-NP mediated anti-tumor efficacy was abrogated. We demonstrated safety of tumor-specific RNA-NPs (derived from KR158b) in acute/chronic GLP toxicity studies without normal-brain cross-reactivity, and confirmed feasibility/safety and immunologic activity in large-animal studies.

FUTURE DIRECTIONS

We have since received FDA-IND approval for first-in-human trials (IND#BB-19304) in glioblastoma patients.
IMMU-24. TEMOZOLOMIDE INDUCED IMMUNE DYSFUNCTION REQUIRES THE PRESENCE OF INTRACRANIAL TUMORS
Authors: Karachi Aida , Dastmalchi Farhad , O’Malley Ashley , Yang Changlin , Mitchell Duane , Rahman Maryam
Published: December 2020

Temozolomide was recently shown to cause peripheral and intra-tumoral T cell dysfunction in a dosing schedule dependent fashion. Standard dose (SD) temozolomide (TMZ) resulted in T cell dysfunction precluding response to immune checkpoint inhibition that was avoided with a metronomic dosing (MD) schedule. Building on these studies, we investigated the TMZ-induced immune changes in tumor and non-tumor bearing models to understand the interaction of an intracranial tumor on host immunity. C57BL/6 mice underwent intracranial implantation of GL-261 tumor cells. Tumor bearing animals and naïve animals with no tumor were treated with standard dose (50 mg/kg x 5 days) or metronomic dose (25mg/kg x 10 days) of TMZ. Peripheral blood and spleens were collected for flow cytometry, ELISA and luciferase killing assay. Tumor bearing animals treated with SD TMZ demonstrated an increase in circulating myeloid derived suppressor cells (MDSCs), an upregulation of exhaustion markers on endogenous host CD8 T cells (TIM3, LAG3) and a decrease in IFN-gamma secretion from adoptively transferred T cells (tested via ELISA). The cell killing capability of adoptively transferred T cells was not reduced after exposure to a TMZ treated host. Non-tumor bearing animals treated with SD TMZ did not demonstrate an increase in circulating MDSCs or exhaustion markers on endogenous T cells. IFN-gamma secretion from adoptively transferred T cells was still reduced in these animals. The host immune dysfunction induced by TMZ is dependent on the presence of an intracranial malignancy. The mechanisms causing these changes are under active investigation.
IMMU-25. SEVERE AND MULTIFACETED SYSTEMIC IMMUNOSUPPRESSION CAUSED BY EXPERIMENTAL CANCERS OF THE CENTRAL NERVOUS SYSTEM REQUIRES RELEASE OF NON-STEROID SOLUBLE MEDIATORS
Authors: Ayasoufi Katayoun , Pfaller Christian , Evgin Laura , Khadka Roman , Tritz Zachariah , Goddery Emma , Fain Cori , Yokanovich Lila , Himes Benjamin , Jin Fang , Zheng Jiaying , Schuelke Matthew , Hansen Michael , Tung Wesley , Parney Ian , Pease Latty , Vile Richard , Johnson Aaron
Published: December 2020

Immunosuppression of unknown etiology is a hallmark feature of glioblastoma (GBM) and is characterized by decreased CD4 T cell counts and down regulation of MHC class II expression on peripheral blood monocytes in patients. This immunosuppression is a critical barrier to the successful development of immunotherapies for GBM. We recapitulated the immunosuppression observed in GBM patients in the C57BL/6 mouse and investigated the etiology of low CD4 T cell counts. We determined that thymic involution was a hallmark feature of immunosuppression in three distinct models of CNS cancer, including mice harboring GL261 glioma, B16 melanoma, and in a spontaneous model of Diffuse Intrinsic Pontine Glioma (DIPG). In addition to thymic involution, we determined that tumor growth in the brain induced significant splenic involution, reductions in peripheral T cells, reduced MHC class II expression on hematopoietic cells, and a modest increase in bone marrow resident CD4 T cells with a naïve phenotype. Using parabiosis we report that thymic involution, declines in peripheral T cell counts, and reduced MHC class II expression levels were mediated through circulating blood-derived factors. Conversely, T cell sequestration in the bone marrow was not governed through circulating factors. Serum isolated from glioma-bearing mice potently inhibited proliferation and functions of T cells both in vitro and in vivo. Interestingly, the factor responsible for immunosuppression in serum is nonsteroidal and of high molecular weight. Through further analysis of neurological disease models, we determined that the aforementioned immunosuppression was not unique to cancer itself, but rather occurs in response to CNS injury. Noncancerous acute neurological insults also induced significant thymic involution and rendered serum immunosuppressive. Both thymic involution and serum-derived immunosuppression were reversible upon clearance of brain insults. These findings demonstrate that CNS cancers cause multifaceted immunosuppression and pinpoint circulating factors as a target of intervention to restore immunity.
IMMU-27. SINGLE CELL RNA-SEQUENCING IDENTIFIES NOVEL BONE MARROW DERIVED MYELOID CELLS IN GLIOBLASTOMA ASSOCIATED WITH TUMOR AGGRESSION
Authors: Jackson Christina , Cherry Christopher , Bom Sadhana , Zhang Hao , Choi John , Yegnasubramanian Vasan , Lim Michael , Elisseeff Jennifer , Pardoll Drew
Published: December 2020

BACKGROUND

Glioma associated myeloid cells (GAMs) can be induced to adopt an immunosuppressive phenotype that can lead to inhibition of anti-tumor responses in glioblastoma (GBM). Understanding the composition and phenotypes of GAMs is essential to modulating the myeloid compartment as a therapeutic adjunct to improve anti-tumor immune response.

METHODS

We performed single-cell RNA-sequencing (sc-RNAseq) of 435,400 myeloid and tumor cells to identify transcriptomic and phenotypic differences in GAMs across glioma grades. We further correlated the heterogeneity of the GAM landscape with tumor cell transcriptomics to investigate interactions between GAMs and tumor cells.

RESULTS

sc-RNAseq revealed a diverse landscape of myeloid-lineage cells in gliomas with an increase in preponderance of bone marrow derived myeloid cells (BMDMs) with increasing tumor grade. We identified two populations of BMDMs unique to GBMs; Mac-1and Mac-2. Mac-1 demonstrates upregulation of immature myeloid gene signature and altered metabolic pathways. Mac-2 is characterized by expression of scavenger receptor MARCO. Pseudotime and RNA velocity analysis revealed the ability of Mac-1 to transition and differentiate to Mac-2 and other GAM subtypes. We further found that the presence of these two populations of BMDMs are associated with the presence of tumor cells with stem cell and mesenchymal features. Bulk RNA-sequencing data demonstrates that gene signatures of these populations are associated with worse survival in GBM.

CONCLUSION

We used sc-RNAseq to identify a novel population of immature BMDMs that is associated with higher glioma grades. This population exhibited altered metabolic pathways and stem-like potentials to differentiate into other GAM populations including GAMs with upregulation of immunosuppressive pathways. Our results elucidate unique interactions between BMDMs and GBM tumor cells that potentially drives GBM progression and the more aggressive mesenchymal subtype. Our discovery of these novel BMDMs have implications in new therapeutic targets in improving the efficacy of immune-based therapies in GBM.
IMMU-34. LANDSCAPE OF GLIOBLASTOMA-ASSOCIATED IMMUNITY BY INTEGRATION OF scRNA-SEQ AND SPATIAL TRANSCRIPTOMICS
Authors: Ravi Vidhya , Neidert Nicolas , Joseph Kevin , Beck Juergen , Schnell Oliver , Heiland Dieter
Published: December 2020

The diversity of molecular states and cellular plasticity of immune cells within the glioblastoma (GBM) environment remain poorly investigated. Here, we conduct deep transcriptional profiling of lymphoid and myeloid cell populations by scRNA-sequencing, map potential cellular interactions and cytokine responses that lead to the dysfunctional and exhausted phenotype of T cells. We identified Interleukin 10 (IL-10) response during T cell activation, which lead to a dysfunctional state of T cells. By the use of a novel method: The nearest functionally connected neighbor (NFCN), an in-silico model to explore cell-cell interaction, the dysfunctional/exhausted phenotype was found to be driven by subset of myeloid cells defined by high expression of HMOX1. By using spatial transcriptomic RNA-sequencing, we identified a correlation between T cell exhaustion and colocalized mesenchymal gene expression. We found that HMOX1 expressing myeloid cells occupying regions marked by T cell exhaustion. Using a human neocortical slice model with myeloid cell depletion we confirmed the functional interaction of myeloid and lymphoid cell leading to the dysfunctional state of T cells. A comprehensive understanding of cellular states and plasticity of lymphoid cells in GBM aids in providing successful immunotherapeutic approaches.
IMMU-36. HIGH AFFINITY CHIMERIC ANTIGEN RECEPTOR WITH CROSS-REACTIVITY TO CLINICALLY-RELEVANT EGFR MUTATED PROTEINS
Authors: Thokala Radhika , Binder Zev , Yin Yibo , Milone Michael , O’Rourke Donald M
Published: December 2020

Tumor heterogeneity is one of the key reasons for therapeutic failure in Glioblastoma (GBM). Our chimeric antigen receptor (CAR) T cell clinical trial (NCT02209376) against Epidermal growth factor receptor (EGFR) variant III (EGFRvIII) demonstrated successful trafficking of T cells across the blood brain barrier into GBM active tumor sites. However, CART cell infiltration was associated with a selective loss of EGFRvIII+ tumor cells and upregulation of immunosuppressive molecules. Post-CAR T treated tumor specimens showed continued presence of EGFR amplification and oncogenic EGFR extracellular domain (ECD) missense mutations. To study this further We generated two structurally different CARs by fusing the scFv of mAb806 to 4-1BB and Killer immunoglobulin like receptor (KIR) co-stimulatory domains. Both 4-1BB and KIR based EGFR806 CAR T cells specifically lysed tumor cells and secreted cytokines when co-cultured with U87-MG (expressing low levels of EGFR) and U87-MG EGFR (U87-MG transduced with EGFR wild type for amplified background) cell lines and engineered to ectopically express targeted EGFR-ECD missense mutations and EGFRvIII. Unlike EGFR-specific cetuximab based CAR, EGFR-806CART cells did not kill EGFR wild type expressing fetal brain primary astrocytes and keratinocytes in vitro. We further evaluated the in vivo efficacy of 806-CARs and EGFRvIII CART currently in clinic in NSG mice. While EGFRvIII CART cells cleared EGFRvIII+ tumors alone 806 CART cells controlled EGFRvIII, amplified EGFR and EGFRR108K-mutant bearing tumors. KIR-CAR treated tumors are GVHD free and enhanced survival compared to 4-1BB based CARs. The broad specificity of EGFR806 CART cells to amplified EGFR and its mutant variants gives us the potential to clear various forms of EGFR. The enhanced anti-tumor efficacy by KIR based CAR in vivo setting provides us with additional therapeutic options.
IMMU-53. CHARACTERIZATION OF THE GENOMIC AND IMMUNOLOGICAL DIVERSITY OF MALIGNANT BRAIN TUMORS THROUGH MULTI-SECTOR ANALYSIS
Authors: Schaettler Max , Richters Megan , Griffith Malachi , Dunn Gavin
Published: December 2020

While the degree of spatial genomic heterogeneity within primary glioblastoma (GBM) has been previously investigated, the extent of this heterogeneity in other malignant brain tumors and its connection to the local immune microenvironment remains unknown. To address this, we performed whole-exome, RNA, and TCR sequencing on multiple spatially distinct sectors from a cohort of malignant brain tumors comprised of both brain metastases and primary and recurrent GBMs. Our results suggest a striking difference in which a majority of mutations and predicted neoantigens are shared between spatially distinct regions of metastatic brain tumors in contrast to the spatial heterogeneity observed within both primary and recurrent GBMs. Additionally, despite substantial differences in immunotherapy responsiveness between brain metastases and GBM, we can detect significantly expanded T-cell clonotypes within both tumor types with some clonal frequencies exceeding 10% of intratumoral T-cells. Similar to the observed distribution of variants and neoantigens, the expanded clonotypes are more shared among spatially distinct sectors in metastatic brain tumors than in primary or recurrent GBMs. Interestingly, the frequencies of most of these enriched T-cell clones are significantly diminished within expanded tumor infiltrating lymphocyte (TIL) cultures, advising caution in the use of expanded TIL for the detection of tumor-specific responses. These results provide novel insight into the immunogenomic landscape of malignant brain tumors with implications for our understanding of tumor-immune interactions and the development of immunotherapies.
INNV-01. NEUROLOGIC IMPROVEMENT WITH CORTICOSTEROIDS PRIOR TO SURGERY IS PREDICTIVE OF DURABLE POST-OPERATIVE IMPROVEMENT IN MOTOR DEFICITS DUE TO BRAIN METASTASES
Authors: Bowden Stephen , Cheaney Barry , Yaghi Nasser , Munger Daniel , Ramos Christian Lopez , Richie Emma , Wood Matthew , Raslan Ahmed , Cetas Justin , Dogan Aclan , Han Seunggu
Published: December 2020

Corticosteroids reduce vasogenic cerebral edema and are thought to improve related neurologic deficits or symptoms of increased intracranial pressure. Brain metastases are typically associated with a large amount of edema and, consequently, come with a disproportionate degree of mass effect that may cause such deficits. There remains no standard approach to pre-operative corticosteroid therapy, nor is it understood what clinical characteristics are associated with a neurologic response to pre-operative steroids. We examined characteristics of steroid responders versus non-responders and, further, evaluated whether a response to preoperative steroids is predictive of durable improvement in neurologic function. Patients with pathology-proven brain metastases who underwent open surgical resection between 2009 and 2019 were identified from departmental records. Charts were reviewed to identify patients with motor dysfunction who received corticosteroids prior to surgery. Multiple patient and clinical characteristics were extracted and compared using student t-, chi-square, and Fisher’s exact tests. 90 patients exhibited pre-operative motor deficits, 69 of whom received corticosteroids prior to surgery (dose 2 – 112 mg; median 25 mg). 34 patients neurologic function improved prior to surgery, whereas 35 patients had no demonstrable improvement. All 34 patients (100%) whose motor function improved pre-operatively with steroids had sustained improvement at follow-up, whereas 27 of 35 (77%) patients who did not improve pre-operatively were better at follow-up (p = 0.005). All other clinical characteristics were similar between responders and non-responders. All motor deficits related to brain metastases that responded to steroids prior to surgery demonstrated durable improvement at follow-up, suggesting such an improvement portends a favorable long-term functional outcome. Conversely, a failure to improve with steroid therapy confers a more guarded prognosis.
INNV-04. CONGENITAL SPINAL GLIOBLASTOMA WITH SUSTAINED RESPONSE TO TROPOMYOSIN RECEPTOR KINASE (TRK) INHIBITION: A CASE REPORT
Authors: Coleman Abadi Christina , Sun Peter , Hastings Caroline
Published: December 2020

Large scale genomic efforts have shown that a significant percentage of infant high-grade gliomas (HGG) carry targetable gene fusions. Given the rarity of congenital spinal HGGs, little is known about the molecular features of these tumors and their response to treatment. We describe a case of a patient with congenital spinal glioblastoma. A full-term female infant with symmetric IUGR was noted to have weakness with little movement of her upper extremities. MRI of the spine showed an infiltrative and hemorrhagic intraspinal cervicothoracic neoplasm with a large hemorrhagic intramedullary component. A biopsy was done and revealed a high-grade glial neoplasm with pan-TRK expression. Next generation sequencing (NGS) confirmed a MEF2D-NTRK1 gene fusion. Prior to the result of her molecular testing, the patient clinically deteriorated with decreased movement and increased apneic episodes despite steroid treatment. She was then started on treatment with carboplatin and etoposide per Macy et al 1. After one cycle of chemotherapy and given the results of NGS, targeted therapy with larotrectinib was added to her treatment. The patient showed a response (clinical and imaging) following cycle 1 with chemotherapy, and a marked response following cycle 2 with both chemotherapy and targeted TRK inhibition. The patient completed six cycles of chemotherapy and has continued on daily oral larotrectinib. She continues to tolerate the targeted therapy well and currently is 8 months old, growing and developing well. She has regained much of her movement and is eating and growing with apparent normal development. This case provides an example of a patient with congenital glioblastoma with TRK gene fusion that showed an impressive response to targeted therapy combined with more conventional chemotherapy. 1Macy M, et al. Clinical and molecular characteristics of congenital glioblastoma. Neuro Oncol. Jul;14 (7) 931–941, 2012).
INNV-13. SYNERGISTIC EFFECT OF COLD ATMOSPHERIC PLASMA IN COMBINATION WITH TEMOZOLOMIDE TO TREAT GLIOBLASTOMA IN A NON-INVASIVE MOUSE XENOGRAFT MODEL
Authors: Adhikari Manish , Soni Vikas , Hayk Simonyan , Young Colin , Sherman Jonathan , Keidar Michael
Published: December 2020

INTRODUCTION

A primary limitation in anti-cancer therapy is the resistance of cancer cells to chemotherapeutic drugs. However, combination therapy may be an effective approach for reducing drug derived toxicity and evading drug resistance, resulting in improved clinical treatment of cancer. Our prior work demonstrated effective treatment of glioblastoma (GBM) with cold atmospheric plasma (CAP) technology with minimal effect to normal cells. Consequently, CAP may serve as a strong candidate for combination therapy with the classical antineoplastic alkylating agent Temozolomide (TMZ) to treat GBM.

OBJECTIVES

To determine the in vivo co-efficacy of CAP and TMZ to “sensitize” GBM.

METHODS

An in vivo study was performed using the CAP jet device (He-gas) to determine the effect of combined CAP–TMZ treatment. U87MG-luc glioblastoma cells were implanted intracranially in athymic nude NU(NCr)-Foxn1nu/immunodeficient mice. He-CAP (or control He alone) was non-invasively applied over the skin for 60sec to developed tumors on the first day of the treatment followed with 6.5 mg/kg TMZ or vehicle control treatment for 5 days for two weeks (n=5/group). In vivo bioluminescence imaging was used to monitor tumor volume on the 6th, 9th and 13th treatment day.

RESULTS

In vivo bioluminescence imaging revealed a marked 8.0±3.2 fold increase in tumor volume in control animals (He-vehicle). Treatment with He-TMZ (6.7±2.5 fold) or CAP-vehicle (4.8±1.7 fold) in isolation had minimal effect in preventing tumor growth. However, combined CAP-TMZ co-treatment virtually prevented increases in tumor volume over 2 weeks (1.8±0.2 fold).

CONCLUSIONS

Collectively, these findings indicate an effective synergistic treatment method for GBM combining CAP with TMZ. Future investigations look to incorporate radiation into the treatment regimen as well as primary GBM cell models.
INNV-17. NEXT GENERATION SEQUENCING IMPACTS OUTCOMES IN RECURRENT PRIMARY GLIOBLASTOMA: A SINGLE-CENTER RETROSPECTIVE ANALYSIS
Authors: Zeitouni Daniel , Catalino Michael , Wise Jordan , Pietrosimone Kathryn , McCabe Sean , Rashid Naim , Khagi Simon
Published: December 2020

BACKGROUND

GBM is driven by various genomic alterations. Next generation sequencing (NGS) may reveal targetable alterations. The goal of this study was to describe how NGS can inform targeted therapy (TT) selection.

METHODS

The medical records of patients (pts) with GBM from 2017–2019 were reviewed. Pts with actionable mutations were included in the analysis. At first progression (PD1), two cohorts of pts were defined: cohort A received TT, while cohort B received physician’s choice chemotherapy (PCC). Regression analyses were used to determine OS and PFS between cohorts. A stratified cox model was utilized to assess the effect of TT, where KPS level (low vs high) was utilized as a stratification factor. A heat map was generated describing the landscape of mutations. Disease response in cohort A was graded per RANO criteria.

RESULTS

There were 38 GBM pts with actionable alterations. Cohort A had 15 (39%) pts and cohort B had 23 (61%) pts. Of the 26 common alterations, 11 (42%) were deemed actionable. Pts with higher KPS were more likely to receive TT. Pts with a KPS ≥ 70 had a longer PFS while on TT. Although not well powered, pts in cohort A had a longer median OS relative to cohort B (HR 0.37 CI 0.10–1.38). The objective response rate (ORR) was 93%, with afatinib and cabozantinib resulting in complete response, one pt had progressive disease while on TT.

CONCLUSION

NGS for recurrent GBM yields a high rate of actionable alterations. Pts that go on TT are often younger and with higher KPS. This likely plays into their improved survival; however, it is notable that the high ORR reflects the value of NGS in deciding on TT to match alterations that are likely to respond. In conclusion, patient selection and availability of NGS impacts outcomes in recurrent GBM.
INNV-19. ANAPLASTIC CEREBELLAR EPENDYMOMA IN AN ADULT FEMALE PRESENTING WITH TONSILLAR HERNIATION SUCCESSFULLY TREATED WITH CHEMOTHERAPY: A CASE REPORT
Authors: Guerrero Victor , Manalo-Igot Mary Ondinee
Published: December 2020

INTRODUCTION

Ependymomas are slow-growing neuroectodermal tumors that may arise from various parts of the central nervous system. Anaplastic ependymoma represents 3–5% of ependymomas and is rarely found in the cerebellum in adults. In this paper, we discuss a case of an adult female with anaplastic cerebellar ependymoma who underwent surgery and chemotherapy for tonsillar herniation.

CASE PRESENTATION

This is a case of a 58-year-old Filipino female with a five-month history of dizziness, headache, nausea and vomiting. Cranial computed tomography (CT) scan revealed presence of hydrocephalus with enhancing lesions at the right cerebellum. The patient underwent ventriculoperitoneal shunting (VPS) with sub-total excision and biopsy of the right cerebellum. Histology and immunochemistry were consistent with a high-grade anaplastic ependymoma (WHO Grade III). Cerebrospinal fluid and spinal magnetic resonance imaging (MRI) were all negative for tumor. The initial plan was to undergo limited field external beam radiation therapy to the cerebellum, however the patient was lost to follow-up. Two months after surgery, she presented with similar symptoms and MRI revealed tonsillar herniation and recurrence of mass compressing the fourth ventricle, pons, and medulla oblongata, thus medical decompression and urgent chemotherapy with cisplatin and etoposide was started. After 4 sessions of chemotherapy, repeat cranial MRI revealed resolution of tonsillar herniation and interval regression of the mass.

CONCLUSION

This paper presented a rare case of anaplastic cerebellar ependymoma with tonsillar herniation who was successfully treated with chemotherapy. Radiotherapy is the standard of care following surgical resection, but the management of our case showed that chemotherapy is also effective in cases when the presentation is herniation.
NCMP-01. THE ROLE OF VASCULAR ENDOTHELIAL GROWTH FACTOR RECEPTOR INHIBITORS IN PREVENTING CEREBRAL RADIATION NECROSIS: A RETROSPECTIVE COHORT STUDY
Authors: Alnahhas Iyad , Rayi Appaji , Palmer Joshua , Raval Raju , Folefac Edmund , Ong Shirley , Giglio Pierre , Puduvalli Vinay
Published: December 2020

INTRODUCTION

Radiation necrosis (RN) is a potential complication after radiation therapy to primary brain tumors and brain metastases. The pathophysiology of RN is not well understood but it is hypothesized that vascular endothelial growth factor (VEGF) plays an important role. Bevacizumab, a monoclonal antibody against VEGF-A, is often successful in the management of RN. The objective of this study is to assess whether VEGF receptor (VEGFR) inhibitors, a group of oral tyrosine kinase inhibitors (TKIs), can prevent or reverse cerebral radiation necrosis

METHODS

We retrospectively studied a cohort of 102 patients with renal cell carcinoma (RCC) and brain metastases seen at The Ohio State University James Cancer Center between 01/01/2011 and 04/30/2019. We identified those who developed RN and analyzed the temporal relationship between the use of VEGFR TKIs and the development of RN.

RESULTS

The cumulative incidence of RN in our cohort is 13.7% after radiation treatments that included LINAC-based stereotactic radiosurgery, fractionated stereotactic radiotherapy, or Gamma Knife radiosurgery. There was no statistically significant difference in the cumulative incidence of RN between patients taking TKIs and patients who were off TKIs (9.9% and 11.5% respectively, p= 0.741). The median time to development of RN was only numerically shorter in patients taking TKIs (151 versus 315 days, p=0.315). One patient developed RN after stopping cabozantinib. Three other patients developed RN while on cabozantinib. Two patients developed RN while on pazopanib, and 3 patients developed RN while on sunitinib. One patient was started on axitinib during active RN without significant improvement subsequently.

CONCLUSIONS

VEGFR TKIs do not consistently prevent or reverse cerebral radiation necrosis and do not seem to have the efficacy that bevacizumab has against RN.
NCMP-09. POSTMORTEM STUDY OF ORGAN SPECIFIC TOXICITY IN GLIOBLASTOMA PATIENTS TREATED WITH A COMBINATION OF TEMOZOLOMIDE, BEVACIZUMAB AND IRINOTECAN
Authors: Zhu Jay-Jiguang , Lu Guangrong , Rao Mayank , Zhu Ping , Linendoll Nadine , Tian Xuejun , Pilichowska Monika , Wu Julian , Glass William , Bhattacharjee Meenakshi , Ballester Leomar Y , Chen Lei , Zhang Rongzhen , Pillai Anil , Buja L Maximilian , Hunter Robert
Published: December 2020

Combined chemotherapy with temozolomide (TMZ), bevacizumab (BEV) and irinotecan (IRI) [TBI] has been used in patients with recurrent or progressive high-grade gliomas. Patients tolerated the regimen well with increased frequency of reversible clinical myelosuppression (CM), hypertension and proteinuria. However, organ-specific toxicities have never been evaluated by post-mortem examination. From 2009 to 2019, post-mortem examinations were performed in seventy-six decedents, including gliomas (N=68, 44/M and 24/F, median age: 59, ranging 23–80 years old) and brain metastases (N=8, 5/M and 3/F, ranging 39–75 years old). Twenty-four glioma subjects were treated with 1–25 cycles TBI (median 5.5) at glioma recurrence. All subjects’ clinical information, treatment histories and adverse events were collected. Five (7.7%, 5/65) glioma decedents (excluding three glioma patients who never received TMZ) permanently discontinued TMZ due to severe CM during concurrent chemoradiation therapy. There is no significantly elevated severity of CM from TBI when compared to standard of care therapies, nor when comparing extended TMZ treatment to the standard 12 cycles of TMZ. However, exposure to IRI significantly increased the CM occurrence (p< 0.05). Among glioma decedents, the most common cause of death was tumor progression (63.2 %, N=43), followed by aspiration pneumonia (48.5%, N=33). No deaths were attributed to acute toxicity from TBI. An electromicroscopic (EM) examination was performed in addition to routine autopsy procedures to investigate the cause of hypertension and proteinuria frequently developing in patients received BEV therapy. Ultrastructural evidence of thrombotic microangiopathy was observed in the kidneys among BEV users; however, it is difficult to conclude such changes were related to BEV due to rapid autolytic changes and artifacts. CONCLUSION: IRI, not the extended use of TMZ, significantly increased the frequency of reversible CM in recurrent glioma patients. There are no unexpected adverse events or organ-specific toxicities detected among glioma decedents who received the TBI regimen.