bluuebunny/crossref_metadata_2025_split huggingface dataset:
EXTH-25. ENHANCING GLIOBLASTOMA CELL STRESS RESPONSE TO IMPROVE GAMMA DELTA T-CELL IMMUNOTHERAPY
Authors: Jones Amber , Rochlin Kate , Lamb Lawrence , Hjelmeland Anita 
Published: November 2021

Abstract
Glioblastoma (GBM) is an aggressive cancer that has been largely intractable to novel therapies, however, enhancing the efficacy of immunotherapy could potentially overcome immunosuppression and potentially improve patient outcomes. The cellular stress induced by Temozolomide (TMZ) increases innate immune ligands, which could be exploited to promote immune recognition. TMZ-induced DNA damage can activate the stress response pathway, increasing the expression of NKG2D ligands (NKG2DL) on tumor cells. This leads to an increase in NKG2DL recognition by NKG2D receptors on both natural killer and cytotoxic T-cells to elicit a cytotoxic effect. The lymphodepleting effect of TMZ, however, can limit the ability of these cells to recognize and kill tumor cells. TMZ was shown to induce NKG2DL in gliomas both in vitro and in vivo, providing the basis for clinical trials of TMZ in combination with genetically engineered TMZ-resistant gamma delta T-cells (NCT04165941). To further promote immune recognition, we sought to augment the TMZ-induced stress response by exploring the combination of DNA alkylation with either PARP (Niraparib) or ATM Kinase inhibition (AZD1390). Combinatorial therapy significantly, but heterogeneously, increased differential subsets of NKG2DL genes in comparison to TMZ alone in GBM cells isolated from patient derived xenografts (PDX): 1) MICA and MICB were increased at least 10-fold in D456 (proneural) cells; 2) ULBP1 and ULBP2 were increased at least 2-fold in JX39 (classical) cells; and 3) minimal increases in NKG2DLs were observed in JX22 (mesenchymal) cells. Repression of NKG2DLs by hypoxia/low glucose was also heterogeneous, being observed in two of three GBM models tested. We are currently determining whether these combinatorial treatments improve gamma delta T-cell cytotoxicity against GBM cells and in vivo tumor models. Taken together, our data suggest that enhancing cell stress responses induced by chemotherapies may permit novel immunotherapy therapeutic interventions for brain tumor patients.
EXTH-30. HARNESSING CELLULAR STRESS FOR IMMUNE TARGETING OF DIPGS
Authors: Gopalakrishnan Vidya , Sharma Ajay , Sridharan Sreepradha , Cheng Donghang , Bournat Juan , Shaik Shavali , Harmanci Arif , Siddaway Robert , Dobson Tara , Swaminathan Jyothishmathi , Allen Joshua , Hawkins Cynthia , Khatua Soumen , Xu Lin , Zaky Wafik 
Published: November 2021

Abstract
Diffuse Intrinsic Pontine Glioma (DIPG) is an incurable pediatric brain tumor. An almost ubiquitous dominant negative mutation at lysine (K)-27 in genes encoding histone genes HIST1H3B and H3F3A found in patient tumors is a driver of DIPG development. ONC201, a small molecule DRD2 antagonist and ClpP agonist developed by Chimerix Inc, targets the unfolded protein response (UPR) and integrated stress response (ISR) signaling. It is under clinical investigation in patients with recurrent H3K27M DMGs. In adults, single agent studies have shown durable objective responses when administered orally. A multi-arm, non-randomized multi-institutional Phase I clinical trial (NCT03416530) for pediatric patients with H3K27M DMGs is open and accruing. Preliminary results suggest that the drug has a favorable safety profile and holds promise for patients with DIPGs and other midline gliomas. However, the mechanism of action of ONC201 against DIPGs warrants further study. Here, we show that ONC201 is cytotoxic to DIPGs in vitro and in vivo. RNA Seq analyses revealed cell context specific deployment of PERK-activated UPR and calcium signaling-associated RON tyrosine kinase-macrophage stimulating protein (MSP) signaling in DIPGs. Single cell proteomic assays revealed substantial heterogeneity in the sensitivity of DIPG cells to ONC201, and identified stem-like sub-populations of H3K27M DIPGs with intrinsic insensitivity to the drug. ONC201 treatment, which induces cellular stress, also sensitized DIPG cells to cytolytic activity by ex-vivo expanded and activated innate immune cells, in vitro. Ongoing in vivo experiments are expected to support a novel investigational study in patients with midline gliomas.
EXTH-33. RETROVIRAL REPLICATING VECTORS PSEUDOTYPED WITH GIBBON APE LEUKEMIA VIRUS ENVELOPE FOR PRODRUG ACTIVATOR GENE THERAPY IN PRECLINICAL GLIOMA MODELS
Authors: Inagaki Akihito , Collins Sara , Freedman Alicia , Montoya Megan , Haddad Alexander , Barcova Maria , Kasahara Noriyuki 
Published: November 2021

Abstract
Amphotropic retroviral replicating vector (RRV) Toca 511, expressing the yeast cytosine deaminase (CD) prodrug activator gene, showed promising evidence of therapeutic benefit and increased survival in early-phase trials for recurrent high-grade glioma. While a multi-center Phase 3 trial did not meet its overall endpoints, highly statistically significant survival was observed within predetermined patient subgroups compared to matched randomized control patients, and clinical investigation is on-going. Hence it is worthwhile to consider strategies aimed at enhancing therapeutic efficacy, such as delivering combinations of multiple transgenes. However, RRVs encoated with the same envelope compete for the same cancer cell surface receptors. We have now developed novel RRV encoated (‘pseudotyped’) with a heterologous envelope derived from Gibbon ape leukemia virus (GALV), which utilizes a different cell surface receptor from the native amphotropic retrovirus envelope for cellular entry. RRV(GALV) vectors expressing either GFP or HSV thymidine kinase (TK) were constructed, and efficient replication and transgene expression was observed in &gt; 90% of both established and primary human glioblastoma cells within 14 days after initial infection at 0.01 (1%) multiplicity of infection (MOI). Genomic stability of RRV(GALV) vectors was also confirmed over prolonged propagation. Established and primary human glioblastoma cells infected with RRV(GALV)-TK vector showed ≥ 50%-90% reduction in cell viability after exposure to Ganciclovir prodrug in the range of 1µM-100µM for 5 days, as compared to uninfected control cells or cells infected with RRV(GALV)-GFP control vector. Furthermore, dual infection with RRV(GALV)-TK and amphotropic RRV-CD (Toca 511) resulted in synergistic cytotoxicity upon simultaneous exposure to their respective prodrugs. Further data will be presented from on-going studies evaluating these vectors in intracerebral glioblastoma models. These results indicate that GALV envelope-pseudotyped RRV can efficiently deliver prodrug activator gene therapy in experimental glioma models, and open the door to combinatorial gene therapy regimens with this vector platform.
EXTH-35. INCREASING THERAPEUTIC INDUCED NEURAL STEM CELL PERSISTENCE IN THE GLIOBLASTOMA TUMOR RESECTION CAVITY
Authors: Bomba Hunter , Kass Lauren , Sheets Kevin , Carey-Ewend Abigail , Goetz Morgan , Bago Juli , Khagi Simon , Hingtgen Shawn , Findlay Ingrid 
Published: November 2021

Abstract

BACKGROUND
Induced neural stem cells (iNSCs) have emerged as a promising therapeutic platform for glioblastoma (GBM). iNSCs have the innate ability to home to tumor foci, making them ideal carriers for anti-tumor payloads. However, iNSC persist for only two weeks in the murine GBM tumor resection cavity. We hypothesized that by encapsulating iNSCs in a scaffold matrix, we could increase both the persistence of the cells the therapeutic durability.

METHODS
iNSCs expressing TRAIL were encapsulated in a gelatin-thrombin matrix; fibrinogen was used to polymerize the matrix. SEM was used to explore interactions between iNSCs and the scaffold matrix. To evaluate persistence, iNSCs encapsulated in the matrix were implanted into mock resection cavities of athymic nude mice and followed via BLI. To study the impacts of encapsulation on iNSC efficacy, athymic nude mice were implanted with U87 or GBM8 tumors. Tumors were then resected, and iNSCs encapsulated in the matrix were implanted; tumor volume was monitored via BLI.

RESULTS
SEM images showed homogeneous distribution of iNSCs throughout the matrix; iNSCs were completed encased in the fibrin clot component of the matrix and did not adhere to gelatin. In vivo, encapsulated iNSCs persisted for nearly 100 days whereas iNSCs directly injected into the brain parenchyma persisted &lt; 20 days. Using mice bearing GBM8 tumors, animals treated with a high dose of therapeutic encapsulated iNSCs survived ~60 days longer than animals treated with non-therapeutic cells. A similar trend was observed in animals inoculated with U87 tumors. While not statistically significant, 25% of mice treated with iNSCs encapsulated in the gelatin-thrombin matrix survived longer than those treated with iNSCs encapsulated in a fibrin-only matrix, suggesting additional benefit due to the gelatin component. FUTURE DIRECTIONS: Prospective experiments will explore the impact of the scaffold on iNSC phenotype, including proliferation, differentiation, and migration markers.
EXTH-38. TARGETING KIF11 TO RADIOSENSITIZE GLIOBLASTOMA
Authors: Zalenski Abby , Tallman Miranda , Kollin Luke , Venere Monica 
Published: November 2021

Abstract
Glioblastoma (GBM) is the most lethal primary brain tumor, with a 5 year survival rate of only 5%. The standard of care for GBM is maximal surgical resection of the tumor, followed by irradiation and chemotherapy. Despite treatment, tumors recur in almost 100% of patients. There are subpopulations of cells in GBM that are radioresistant and chemoresistant, and new treatments will need to inclusively target these cells. KIF11 is a mitotic protein that drives bipolar spindle formation and is crucial for successful completion of mitosis. We previously reported that KIF11 is overexpressed in GBM over normal brain tissue, and that inhibiting KIF11 in a patient-derived xenograft (PDX) GBM mouse model increased survival. However, in this model, tumors recurred after treatment was stopped, indicating that treatment may have had a cytostatic effect, rather than cytotoxic. Importantly, it has been reported that cells are most vulnerable to irradiation when they are in mitosis. Because using a KIF11 inhibitor arrests cells in mitosis, we hypothesized that combining irradiation and a KIF11 inhibitor would radiosensitize GBM cells, and lead to greater tumor cell death. In this study, we found that combination therapy increased cell death over vehicle or either treatment used alone in patient-derived GBM cells in vitro. Additionally, we found that inhibiting KIF11 combined with radiotherapy increased survival over vehicle or monotherapy in orthotopic PDX models. Our results demonstrate that combining KIF11 inhibitors with radiotherapy is a promising potential therapy for GBM.
EXTH-48. NOVEL COMBINATION THERAPY IN PRECLINICAL GLIOMA MODELS USING THE CELL CYCLE STABILIZING COMPOUND ARGYRIN F AND CHECKPOINT INHIBITION
Authors: Walter Bianca , Canjuga Denis , Yuez Simge G , Ghosh Michael , Bozko Przemyslaw , Przystal Justyna , Govindarajan Parameswari , Anderle Nicole , Keller Anna-Lena , Tatagiba Marcos , Schenke-Layland Katja , Rammensee Hans-Georg , Stevanovic Stefan , Malek Nisar P , Schmees Christian , Tabatabai Ghazaleh 
Published: November 2021

Abstract
Glioblastoma are incurable aggressive tumors and remain a therapeutic challenge. Glioblastoma frequently harbor alterations in the retinoblastoma pathway with subsequent cell cycle abnormalities. Here, we aimed to investigate the anti-glioma activity of the cell cycle-stabilizing compound Argyrin F and its potential treatment-induced vulnerabilities to exploit possibilities for novel combination therapies. We investigated cell viability, clonogenic survival, cell cycle status and immunoblots of human and murine glioma cells treated with Argyrin F. Moreover, we established an ex vivo glioma model using residual freshly resected tissue from patients, i.e. patient-derived microtumors (PDMs). Additionally, we extracted autologous tumor infiltrating lymphocytes (TILs) to perform co-culturing experiments. We performed mass spectrometry-based immunopeptidomics and used the orthotopic syngeneic SMA560/VM/Dk glioma mouse model. Argyrin F displayed anti-glioma efficacy in glioma cell lines in vitro and in PDM models ex vivo. Moreover, Argyrin F treatment induced cell cycle arrest, reduced clonogenic survival in vitro and prolonged survival in vivo. Argyrin F-treated SMA560 glioma displayed 4.6-fold more glioma-infiltrating CD8+ T cells. We discovered a distinctive treatment-induced immunopeptidome. Combination of Argyrin F plus PD-1 antibody increased cellular toxicity in PDM/TILs co-cultures ex vivo and prolonged overall survival compared with monotherapies in vivo. We conclude that our experimental data suggest a novel combination of Argyrin F plus PD-1 blockade and its clinical translation.
EXTH-56. ZIKA VIRUS TREATMENT SIGNIFICANTLY PROLONGS SURVIVAL IN A GLIOBLASTOMA PATIENT DERIVED XENOGRAFT MODEL
Authors: Akhtar Parvez , Zwernik Samuel , Donohoe Deborah , Warner Catherine , Bosenko Dmitry , Rovin Richard 
Published: November 2021

Abstract
The poor median survival for patients with glioblastoma (GBM) of 15 months has not budged for the past 15 years, when the current standard treatment was first approved. There is no standard of care chemotherapy for recurrent GBM. We previously showed that Zika virus (ZIKV) tropism for GBM cells is mediated through the receptor tyrosine kinase, AXL. This infection is cytotoxic. In this study we show that ZIKV is an effective oncolytic virus in a patient derived xenograft model. Fox N1 Nude homozygous female mice 6-8-weeks-old were grouped into 4 experimental arms: two patient derived cell lines, each with a ZIKV treated and a control group. There were 12 mice in each arm. Animals received subcutaneous flank injections of GBM 8049 or its AXL CRISPR knockout 8049 AXLKO (2x106 cells). When tumors reached 200 mm3, mice received intra-tumoral injection of 2.5x106 ZIKV particles or saline. ZIKV induced complete tumor remission in 22 of 24 animals (8049: 11/12; 8049 AXLKO: 11/12). There was no tumor remission in the saline treated animals. Median survival of 8049 and 8049 AXLKO ZIKV treated mice was 124 days and 125 days, respectively. This is compared to median survival of control animals 8049: 42 days; 8049 AXLKO: 46 days (P= 0.001). Among ZIKV treated mice, there were two recurrences: one in the 8049 tumor (24 days after significant tumor remission) and one 8049 AXLKO tumor (7 days after significant tumor remission). We conclude that ZIKV should be considered a candidate oncolytic virus for GBM.
EXTH-57. EFFICACY OF SOLUBLE PANOBINOSTAT (MTX110) IN PRECLINICAL MODELS OF ADULT GLIOBLASTOMA
Authors: Palmer Greg , Keir Stephen T , Ashley David M , Davies Rhian , Williams Ben , Rees Zoe , Laemont Keith , Belloni Rafaela , Damment Stephen J P , Conlon Kelly 
Published: November 2021

Abstract

INTRODUCTION
One of the biggest challenges in treating glioblastoma is achieving effective local drug concentrations, and trials using systemic administration of therapeutics have failed in GBM despite compelling pre-clinical evidence. MTX110 (Midatech Pharma PLC) is a water-soluble form of panobinostat currently in clinical development for DIPG and medulloblastoma using direct tumor delivery. We have previously reported a significant positive benefit of MTX110 in a subcutaneous GBM mouse model in an IDH1 mutated cell line. Here we present follow on data on the potential for MTX110 synergy with radiation in pre-clinical in vivo models. We also present data on efficacy of MTX110 in a panel of GBM cell lines.

METHODS
In vitro: Cell lines were incubated with MTX110 for 72h over a range of concentrations (1nM-10µM). Each concentration was tested in triplicate with the appropriate blank controls included in each plate. After 72 hours, cell viability was measured via luminescence signal (Promega CellTiter-Glo Luminescent Cell Viability Assay kit (Promega-G7573) read via 2104 EnVision Multilabel Reader, PerkinElmer. In vivo: Tumor-bearing mice were stratified to either the vehicle control or treatment group based on median tumor volume and were treated with MTX110 at a dose of 15mg/kg IP, 5 days consecutively for 2 consecutive weeks, following radiation treatment at a dose of 4Gy delivered as a single fraction on day 1.

RESULTS
In vitro, MTX110 demonstrated cytotoxic activity in 4 GBM cell lines (U87MG, U251MG, U118MG and T98G) with an average IC50 value in the region of 40nM (17-43nM). In vivo MTX110 in combination with radiation treatment showed an enhanced delay in tumor growth of approximately 50% compared to MTX110 or radiation alone. The results are supportive of the planned exploratory trial in GBM with MTX110.
EXTH-58. THERAPEUTIC HDAC INHIBITION IN HYPERMUTANT DIFFUSE INTRINSIC PONTINE GLIOMA
Authors: Noll Alyssa , Biery Matt , Myers Carrie , Paine Danyelle , Zheng Ye , Girard Emily , Winter Conrad , Morris Shelli , Brusniak Mi-Youn , Gottardo Raphael , Mhyre Andrew , Foster Jessica , Dun Matthew , Murtaza Muhammed , Berens Michael , Olson James , Vitanza Nicholas 
Published: November 2021

Abstract
Diffuse intrinsic pontine glioma (DIPG) continues to carry a dismal prognosis despite a growing understanding of its epigenetic regulation. While generally reclassified as diffuse midline glioma, H3 K27M-mutant (DMG), a subgroup of DIPGs do not harbor the classic histone mutation, with a further subset exhibiting a hypermutant phenotype. To evaluate whether hypermutant DIPG shares transcriptional vulnerabilities with H3K27M-mutant DMG, we screened a biopsy-derived treatment-naive PMS2 mutant DIPG model (PBT-24FH) for sensitivity to a panel of HDAC inhibitors (HDACi). In vitro evaluation of cell viability revealed the low nanomolar IC50 of quisinostat (50nM) and romidepsin (2nM). Dose-dependent increases in H3 acetylation and c-PARP were confirmed by western blot. Despite romidepsin’s superior potency in vitro, quisinostat demonstrated greater efficacy in an in vivo PBT-24FH flank study. 42 days following drug initiation, quisinostat-treated mice displayed dramatic tumor regression (mean volume= 33mm3, n= 7) compared to mice treated with romidepsin (mean volume= 669mm3, n= 7)(p= 0.005), or vehicle (mean volume= 990mm3, n= 6)(p&lt; 0.001). Immunohistochemistry of quisinostat-treated tumors revealed few residual tumor cells displaying a low proliferative index. To evaluate cross-resistance, romidepsin-treated mice (mean volume= 1158mm3, n= 2) were switched to quisinostat treatment and displayed swift tumor regression (mean volume after 25 days of quisinostat= 419mm3), emphasizing quisinostat’s in vivo cytotoxic effect against both large tumors and tumors previously treated by another HDACi. To evaluate quisinostat’s effect on other hypermutant tumors, we tested HCT-116, a colon cancer cell line bearing a biallelic MLH1 deletion and observed similar cytotoxicity. We also aim to repeat these studies utilizing additional pediatric hypermutant high grade glioma models. Transcriptomic and proteomic investigations are underway to identify the mechanism of action underlying quisinostat-induced cytotoxicity. Ultimately, we are the first to demonstrate in vivo efficacy of the HDACi quisinostat against hypermutant DIPG, supporting further investigation and clinical advancement.
EXTH-59. GENERATION OF A THIRD GENERATION CAR T CELL THAT SIMULTANEOUSLY TARGETS WILDTYPE EGFR AND ITS MUTANT ISOFORM EGFRVIII FOR TREATMENT OF GLIOBLASTOMA
Authors: Wilkinson Daniel , Ryan Katherine , Chandramohan Vidyalakshmi , Landi Daniel , Bigner Darell , Fecci Peter 
Published: November 2021

Abstract
Glioblastoma (GBM) is the most aggressive primary brain cancer with a median survival of less than 16 months. This dire prognosis signifies the urgent need for improved treatment options, such as immunotherapy. Chimeric antigen receptor (CAR) T cells have helped revolutionize immunotherapy, achieving considerable success in eliminating hematological cancers but generally failing to control solid tumors. One major hindrance to CAR T cell success in solid tumors is tumor heterogeneity. Tumor-associated or tumor-specific antigens (TAA or TSA, respectively) are rarely expressed by all malignant cells within a tumor. As a specific example in GBM, the most prevalent TSA, EGFRvIII, is present in just 30% of tumors, and then on only 30-50% of cells. Our pre-clinical and clinical experiences with CAR T cells reveal that tumors possessing as few as 5-10% EGFRvIII-negative cells will easily escape EGFRvIII-targeted CARs. Tumor cells that lack EGFRvIII expression often overexpress the wildtype isoform of EGFR (EGFRwt). Notably, EGFR is absent on normal brain. Therefore, a superior approach would be to simultaneously target EGFRvIII and EGFRwt, an approach that would bypass EGFR heterogeneity in EGFRwt/EGFRvIII-expressing tumors. Here, we generated a third generation CAR using the D2C7 single-chain variable fragment (scFv) targeting moiety that recognizes an epitope present in EGFRwt and EGFRvIII. Initial in vitro characterization of D2C7 CAR validated the specificity and function of D2C7 CAR, as it potently killed murine cell lines engineered to express either EGFRwt or EGFRvIII, but not a cell line expressing neither. Concomitant IFN-γ release supported these conclusions. Additionally, D2C7 CAR killed the human-derived GBM cell line U87 and vIII-transfected U87, U87vIII. Importantly, intracranially-administered D2C7 CAR significantly prolonged survival of mice bearing orthotopic U87vIII or U87/U87vIII heterogeneous tumors compared to mock-treated controls. Altogether, these data provide evidence that D2C7 CAR T cells represent a viable therapeutic option for EGFRwt/EGFRvIII heterogeneous tumors.
EXTH-63. A NOVEL MOUSE MODEL OF DIFFUSE MIDLINE GLIOMA FOR TARGETED IMMUNOTHERAPY
Authors: Seblani Maggie , Zannikou Markella , Duffy Joseph , Levine Rebecca , Liu Qianli , Horbinski Craig , Becher Oren , Balyasnikova Irina 
Published: November 2021

Abstract
In children, diffuse midline gliomas retain poor outcomes, failing to have a durable response to conventional therapies. Immunotherapies hold promise, with the integration of the host's immune system fundamental to their design. Here, we describe a novel genetically engineered immunocompetent model that incorporates interleukin 13 receptor alpha 2 (IL13Rα2), a tumor-associated antigen, to evaluate the antitumor activity of IL13Rα2-CAR T cell and bispecific T cell engager (BiTE) therapies in preclinical studies. The RCAS-Tva delivery system was utilized to induce gliomagenesis through p53 loss and the constitutive expression of PDGFB and human IL13Rα2 in Nestin-Tva;p53fl/fl mice. Pups were injected with virus-producing DF1 cells, encoding either for RCAS-Cre and PDGFB+IL13Rα2 or RCAS-Cre and PDGFB. Kaplan-Meier survival curves established and compared tumor growth dynamics in both models. Tumor tissue was characterized through immunohistochemistry and H&E staining. Cell lines generated from tumor-bearing tissue were used for orthotopic injection and in vitro studies. Expression of PDGFB and IL13Rα2 was confirmed by flow cytometry and western blot. In both groups, de novo tumors developed without significant difference in median survival between RCAS:PDGFB (n=25, 40 days) and RCAS:PDGB+IL13Rα2 (n=32, 39 days). Tumors demonstrated characteristics of high-grade glioma such as infiltration, pseudopalisading necrosis, microvascular proliferation, high Ki-67 index, heterogenous IL13Rα2 expression, with notable presence of CD11b+ macrophages and low count of CD3+ T cells. Orthotopic tumors from developed cell lines were histologically similar to de novo tumors. Treatment of generated cell lines with IL13Rα2-targeting BiTE protein resulted in a loss of glioma cell viability and target-specific activation of T cells. Engineered de novo tumors possess histopathologic features common to diffused midline gliomas. IL13Rα2-positive cell lines derived from de novo tumors were responsive to targeted treatment, opening the opportunity for preclinical assessment of IL13Rα2-directed immunotherapies, with the potential for clinical translation.