bluuebunny/crossref_metadata_2025_split huggingface dataset:
EXTH-29. INTERNEURONS THAT BITE, A CELLULAR THERAPY FOR HIGH GRADE GLIOMA
Authors: Brosius Stephanie , Manley William , Anderson Stewart , De Raedt Thomas 
Published: November 2023

Abstract
Glioblastoma has a poor prognosis with limited therapeutic options. Cellular therapies, like CAR-T therapy, have unfortunately shown limited efficacy for brain tumors, due to the lack of unique tumor antigens, the downregulation of targeted antigens, and the immune suppressive tumor microenvironment (TME). To circumvent these brain tumor specific obstacles, we developed a cellular immunotherapy delivery system, derived from post-mitotic Migratory Cortical Inhibitory Interneuron Precursors (MCIPs), that induces a cytotoxic tumor response in glioblastoma independent of unique tumor antigens. During fetal brain development, MCIPs are chemoattracted to migrate long distances from their subcortical origins into the cerebral cortex. The MCIP chemoattractant CXCL12 activates CXCR4 to induce this migration. Intriguingly, CXCL12 is secreted by glioblastoma, suggesting they chemoattract MCIPs. Excitingly, our in vitro and in vivo data indeed show that MCIPs robustly migrate to the majority of glioblastoma cell lines evaluated. Crucially, this migration is independent of unique tumor antigens and the TME and provides us with the opportunity to use MCIPs as a delivery vector for cytotoxic agents. In one approach, we successfully eliminated EGFR expressing glioblastoma in vivo by modifying MCIPs to secrete EGFR Bispecific T-cell Engagers (BiTE). BiTE engagement with a tumor cell results in T-cell activation and elimination of the engaged tumor cell. Importantly, the T-cells have no innate recognition of the tumor cell, this is provided by the BiTE. Local EGFR BiTE secretion has limited systemic toxicity, thereby making EGFR a viable non-unique target. MCIPs can be equipped with a range of agents that eliminate glioblastoma. As a therapy, we envisage injecting modified MCIPs, differentiated from patient or donor “off the shelf” induced pluripotent stem cells, into the margin of the surgical cavity to “clean-up” tumor cells remaining post-surgery. An interneuron clinical trial for epilepsy (NCT05135091) is ongoing, highlighting the translational potential of our MCIP cellular therapy.
EXTH-45. DEVELOPMENT OF COMBINATION THERAPIES OF KRASG12C INHIBITOR ADAGRASIB IN PRECLINICAL MODELS OF BRAIN METASTASIS
Authors: Torrini Consuelo , Migliarese Christian , Summers Elizabeth , Demir Fatma Turna , Ijad Nazanin , Nayyar Naema , Yamazawa Erika , De Sauvage Magali , Brastianos Priscilla , Wakimoto Hiroaki 
Published: November 2023

Abstract

BACKGROUND
The highly selective KRASG12C inhibitor adagrasib (MRTX849) is FDA-approved for KRASG12C+ advanced non-small cell lung cancer (NSCLC). We recently provided preclinical evidence of MRTX849 brain penetration and activity, allowing MRTX849 inclusion in a national genomically-guided multicenter clinical trial (NCT03994796) for patients with brain metastasis (BM). However, multiple genetic alterations such as CDKN2A/B deletions, a common driver of NSCLC BM, can limit MRTX849 efficacy. Furthermore, although MRTX849 can sensitize extracranial tumors to immune checkpoint inhibitors (ICI), its intracranial immune benefit is unknown. Our objective was to improve MRTX849 monotherapy, evaluating combination therapies with CDK4/6 inhibitor abemaciclib or anti-PD-1 in preclinical models of BM.

METHODS
We tested in vitro sensitivity of MRTX849 and abemaciclib, using KRASG12C+, CDKN2A-deleted human lung cancer cell lines SW1573 and H2122. The efficacy of a 5-week treatment of MRTX849 and abemaciclib was evaluated in an intracranial NSCLC BM model in nude mice. Additionally, we utilized a syngeneic murine KrasG12C colorectal cancer BM model (CT26G12C) to test different MRTX849 dosages and assess its therapeutic effects in combination with anti-PD-1 antibody.

RESULTS
MRTX849 and abemaciclib demonstrated mild synergy in reducing cell viability in vitro. Combination treatment of MRTX849 and abemaciclib significantly improved both survival and intracranial tumor control relative to controls in SW1573 NSCLC BM model. In a syngeneic colorectal BM model, we identified benefit of a 2-week MRTX849 single treatment at 100 mg/kg (BID) in controlling brain tumor growth. In a dual subcutaneous intracranial BM model with CT26G12C, MRTX849 alone and combination therapy mediated complete regression of extracranial tumors. Although monotherapies reduced intracranial tumor growth, MRTX849 combination with anti-PD-1 resulted in a greater benefit. Both MRTX849 monotherapy and the combination therapy extended animal survival.

CONCLUSIONS
MRTX849 combination therapies with abemaciclib or anti-PD-1 demonstrate intracranial activity, inhibiting BM progression and prolonging survival, in preclinical models of KRASG12C+ BM.
EXTH-50. ACUTE AND LONG-TERM RESPONSES TO QUISINOSTAT TREATMENT IN PDX MODELS OF GLIOBLASTOMA
Authors: Orndorff Keely , McNamara James , LoCascio Costanza , White Connor , Stavnichuk Mariya , Shaik Kamal , Margaryan Tigran , Tovmasyan Artak , Sanai Nader , Mehta Shwetal 
Published: November 2023

Abstract

BACKGROUND
Histone deacetylase inhibitors (HDACi) promote reactive oxygen species production, result in DNA damage, and trigger cell fate changes. Quisinostat is a Class I-II selective HDAC inhibitor with high specificity for HDAC1. Here, we evaluated acute and long-term quisinostat treated glioblastoma (GBM) PDX tissues and glioma stem cells for increase in reactive oxygen species and cell fate change.

METHODS
GBM PDX models (n = 6) and multiple PDX-derived glioma stem cells were treated with quisinostat, radiation, or a combination of quisinostat and radiation. Tissue and cells were processed via LC-MS/MS, RNA-seq, qRT-PCR, immunoblotting, and immunocytochemistry assays to examine increase in cellular reactive oxygen species, oxidative stress biomarkers, and markers of stemness and differentiation.

RESULTS
RNA sequencing of tumor tissue revealed that chronic co-treatment with quisinostat and radiation led to increased cellular expression of oxidative stress- and neuronal-related genes compared to control group. Immunoblotting confirmed upregulation of neuronal signaling proteins in the quisinostat treated tumor tissue in vivo. qRT-PCR and LC-MS/MS analysis demonstrated an increase in oxidative stress biomarkers following acute quisinostat treatment in vitro.

CONCLUSIONS
Treatment with quisinostat increased the expression of genes involved in promoting oxidative stress and neuronal signaling in vivo. LC-MS/MS, qRT-PCR, immunoblotting and immunocytochemistry assays confirmed increase in oxidative stress and neuronal markers upon acute treatment in vitro. Cancer cells often express higher levels of reactive oxygen species compared to normal tissue, and oxidative stress is linked to greater survival and proliferation of cancer cells. However, there is much interest in increasing oxidative stress in glioma cells to induce selective cell death in cancer cells. Ongoing studies are aimed at evaluating the significance of these cellular and molecular changes resulting from quisinostat treatment and whether the quisinostat-induced oxidative stress and cell fate changes can be exploited for future combination therapy for GBM.
EXTH-52. LONG-ACTING RECOMBINANT INTERLEUKIN-7, NT-I7, IMPROVES SURVIVAL FOLLOWING ONCOLYTIC ZIKA VIRUS TREATMENT IN THE SB28 IMMUNOSUPPRESSIVE AND TREATMENT-RESISTANT MURINE GLIOMA MODEL
Authors: Li Yuping , Hu Tong , Kesarwani Ashwani , Costa Amanda De Andrade , Illindala Ritvik , Wolfarth Alexandra , Ferrando-Martinez Sara , Yang Se Hwan , Lee Byung Ha , Diamond Michael S , Chheda Milan 
Published: November 2023

Abstract
Glioblastoma (GBM) does not respond to immunotherapy for several reasons, including limited cancer-specific neoantigens and poor T-cell infiltration. The SB28 murine glioma model recapitulates these aspects of human GBM. Zika virus (ZIKV) treatment of GL261 and CT2A-bearing mice resulted in significant survival improvement through multiple mechanisms, including direct tumor killing and induction of a local CD8+ T-cell anti-tumor response, but ZIKV is less effective against SB28 tumors. Previously, we published that a long-acting human IL-7, rhIL-7-hyFc (NT-I7, efineptakin alfa; NeoImmuneTech Inc.), increases T-cell abundance and improves tumor infiltration. Therefore, we hypothesize that combining NT-I7 with oncolytic ZIKV therapy will enhance the anti-tumor response and improve survival in mice bearing SB28 syngeneic tumors. 1×103 SB28 tumor cells were intracranially implanted in C57BL/6J mice. Mice were treated with NT-I7 on post tumor implantation day 7 and 10, followed by intratumoral ZIKV on day 14. Tumor burden was assessed using bioluminescence imaging; mice were monitored for survival and bled weekly to assess the systemic T-cell response to NT-I7. Subcutaneous injection of NT-I7 significantly boosted systemic T-cell abundance compared to control (5,623 cells/uL vs. 136 cells/uL, p &lt; 0.05), particularly cytotoxic CD8+ T-cells (4,776 cells/uL vs. 47 cells/uL, p &lt; 0.05). This increased abundance of CD8+ T-cells peaked at 7 days after initial treatment and persisted for 21 days. NT-I7 monotherapy did not confer any survival benefit. However, the combination of NT-I7 and ZIKV treatment resulted in significant improvement in survival compared to NT-I7 or ZIKV treatment alone (p &lt; 0.05). Treatment with NT-I7 primes the immune system by expanding the circulating CD8+ T-cell population by 100-fold. Timing the oncolytic ZIKV injection with the peak in peripheral CD8+ T-cells greatly improved survival in the immunotherapy resistant SB28 glioma model. These data suggest a role for NT-I7 as an adjunct to various T-cell mediated treatment strategies for GBM.
EXTH-57. THE IGF-2 SIGNALING PATHWAY IS A PROMISING MENINGIOMA TREATMENT TARGET
Authors: Uhlmann Erik , Rabinovsky Rosalia , Mackel Charles , Deforzh Evgeny , Vega Rafael , Varma Hemant , Krichevsky Anna 
Published: November 2023

Abstract
Meningioma is the most common primary central nervous system tumor often causing serious complications while there is no effective medical treatment. We developed a tumor-derived primary culture model featuring tumor cells with retained PDG2S lineage marker as well as non-arachnoid cells mimicking the tumor cell microenvironment. We used this model to test the relevance of miRNA differentially expressed in meningioma tumor samples identified by small RNA sequencing. We found that in all meningiomas studied, there was activation of the IGF2/miR-483 locus with high expression of both miR-483-5p and IGF2. Inhibition of miR-483-5p reduced the growth of cultured meningioma cells, whereas a miR-483 mimic increased cell proliferation. Anti-IGF2 neutralizing antibodies reduced meningioma cell proliferation. Small molecule tyrosine kinase inhibitor blockade of the IGF2 receptor (IGF1R) resulted in rapid loss of viability of cultured meningioma tumor-derived cells. Autocrine IGF2 feed-back appears to be obligatory for meningioma tumor cell survival and growth. Inhibition of this circuit with IGF1R small molecule tyrosine kinase inhibitors or receptor-binding antibodies as well as anti-IGF2 neutralizing antibodies may have therapeutic potential for meningioma.
EXTH-62. COMBINATIONAL TREATMENT OF G-QUADRUPLEX STABILIZER CX-5461 AND IONIZING RADIATION POTENTIATES SELECTIVE LETHALITY IN PRECLINICAL ATRX-DEFICIENT GLIOMA MODELS
Authors: Dharmaiah Sharvari , Malgulwar Prit Benny , Johnson William E , Chen Brandon A , Farooqi Ahsan S , Huse Jason 
Published: November 2023

Abstract
Mutations in α-thalassaemia/mental retardation X-linked (ATRX) are a critical molecular marker for fatal high-grade glioma (HGG). Standard of care has remained stagnant in the last 30 years, with no therapies approved specifically for ATRX-deficient glioma. ATRX mutations give rise to abnormal DNA secondary G-quadruplex (G4) structures at GC-rich regions of the genome, altering genome-wide accessibility of chromatin and enhancing DNA damage. We aim to use G4 stabilizers, a class of novel small molecule compounds that selectively bind to and stabilize G4s, to enhance DNA damage and induce cell death in ATRX-deficient glioma. Using patient-derived glioma stem cells (GSCs) and the G4 stabilizing compound CX-5461 (Senhwa Biosciences), we evaluated the efficacy of G4 stabilization as a single agent and in combination with ionizing radiation (IR). As IR is standard of care and DNA-damaging, it may hold strong potential to synergize with CX-5461. Here, we report that ATRX-deficient GSCs demonstrate dose-sensitive lethality to CX-5461, compared to controls. Mechanistic studies reveal that CX-5461 activates p53-independent apoptosis, exhibits G2/M arrest in ATRX-deficient GSCs, and upregulates G4s (BG4), replication stress (ATR, RPA32) and DNA damage (ATM, γH2AX) pathways specifically in ATRX-deficient GSCs. These functional findings are corroborated by ATRX-deficient and -intact GSC flank xenograft mouse models, which were separated into the following treatment groups: 1) vehicle, 2) CX-5461 alone, 3) IR alone, 4) CX-5461 and IR (n = 20/group). Excitingly, we demonstrate that combinational treatment leads to profound tumor growth delay exclusively in ATRX-deficient flank tumors compared to vehicle (p = 0.0004), CX-5461 alone (p = 0.0001), or IR alone (p = 0.0002) groups. Multiplex immunohistochemistry of CX-5461 alone and the combinational treatment tumors shows enhanced induction of G4s, replication stress, and DNA damage, recapitulating in vitro findings. Taken together, our work defines mechanisms of action and efficacy for a novel therapeutic strategy for pre-clinical ATRX-deficient HGG, with strong implications for clinical translation.
EXTH-70. UTILIZING ONCOLYTIC VIROTHERAPY AS AN APPROACH TO ENHANCE NEOANTIGEN SPECIFIC IMMUNE RESPONSES IN GLIOBLASTOMA
Authors: Piranlioglu Raziye , Ahn Ryujin , Islam Anan , Nowicki Michal , Ling Alexander , Soni Himanshu , Ahuja Ved V , Goins William F , Irvine Darrell J , White Forest M , Nakashima Hiroshi , Antonio Chiocca E 
Published: November 2023

Abstract
Despite the success in treating many solid cancers, immunotherapy has not shown significant efficacy in patients with glioblastoma (GBM). The lack of tumor-infiltrating T cells recognizing tumor antigens displayed with major histocompability complex I (MHC I) is one of the reasons for GBM’s evasion from immunotherapy. Our preclinical GBM models and an ongoing clinical trial with oncolytic herpes simplex virus-1 (oHSV) at our institution (NCT03152318) demonstrated that oHSV treatment leads to an increase influx of CD8+ and CD4+ T cells into tumor. However, it remained unclear whether these T cells are specific to the tumor antigens (neoantigens) or reactive to only viral antigens. To determine whether infiltrating CD8 T cells target tumor antigens, we first performed whole-exome and RNA sequencing of CT2A, a preclinical model of GBM impervious to immunotherapies for identification of neoantigens. We screened immunogenicity of identified neoantigens by ELISPOT assay. TILs from the oHSV-treated (but not from control group) reacted to two of the neoantigens that were identified with our pipeline and this activation was similar in magnitude to the reaction to the immunodominant HSV antigen. FACS analyses of TILs seven days after virotherapy showed that oHSV-treated tumor had higher level of TILs than vehicle control tumors, a finding that mirrored what we observed in our phase 1 clinical trial with oHSV. High dose of oHSV treatment not just induces the infiltration of viral specific T cells, but infiltration of T cells targeting neoantigens that were not presented without OV infection. Phosphoproteomic analysis of bulk tumor revealed activation of key inflammatory pathways, including that of T cells receptor signaling upon virus treatment. We evaluated the efficacy of therapeutic neoantigen vaccination in combination with oncolytic intratumoral virotherapy. Survival analysis showed that combination therapy not just delays the tumor progression but also provides survival advantage compared to monotherapies.
EXTH-79. A NOVEL ANTI-GALECTIN-3 ANTIBODY THERAPEUTIC SYNERGIZES WITH TEMOZOLOMIDE IN PRECLINICAL MODELS TO DIMINISH TUMOR GROWTH, DECREASE MIGRATION, AND PROLONG SURVIVAL
Authors: Barrette Anne Marie , Deshpande Krutika , McDonald Bailey , Cadiente Marvin , Wang Xi , Sun Dongxu 
Published: November 2023

Abstract
Glioblastoma (GBM) is the most aggressive, invasive, and malignant primary brain cancer whose standard of care for nearly 20 years has been surgical resection followed by radiotherapy and temozolomide (TMZ) treatment, resulting in a median survival of 15 months following diagnosis. Heterogenous tumor cell populations that evade resection and develop chemoradiation resistance highlight the need for novel therapies that can target both the migratory and proliferative nature of GBM cells. Galectin-3, a carbohydrate-binding protein overexpressed in the GBM parenchyma and stromal astrocytes, is a potent modulator of cell proliferation, migration, angiogenesis, T-cell inhibition, and M2 macrophage polarization, and is seen to increase following TMZ and radiation treatment. Heightened Galectin-3 expression levels correlate to lower survival in glioma patients, thus greatly underscoring the need for targeting Galectin-3 in conjunction with initial standard-of-care treatment. Here, we characterize the therapeutic effects of a brain-penetrant monoclonal anti-Galectin-3 antibody (Gal3 Ab) we have developed for its ability to inhibit GBM growth and migration in several in vitro assays and in vivo heterotopic and orthotopic mouse models. Our Gal3 Ab significantly decreases cell viability, neurosphere migration, and cell invasion in vitro in the presence of full length or truncated Gal3, whose expression and secretion in GBM cells is enhanced following short and long-term TMZ stimulation. We find that Galectin-3 directly binds to EGFR, amplified in ~40% of GBM patients, as well as its most commonly mutated form, EGFRvIII, and our Gal3 Ab can block these bindings, decrease EGFR activation, and alter EGFR localization. In vivo, our Gal3 Ab decreases tumor burden and improves survival in combination with temozolomide, compared to standard-of-care treatment alone in multiple cell-line models. Our pre-clinical studies highlight the potential for our novel Gal3 antibody to further improve TMZ efficacy and benefit GBM patients by diminishing tumor cell migration and slowing tumor growth.
EXTH-81. RE-EXPRESSION OF CXCL9 FOLLOWING ADENO-ASSOCIATED VIRUS (AAV) TRANSGENE DELIVERY TRANSFORMS THE IMMUNOLOGICAL LANDSCAPE OF GLIOBLASTOMA, SENSITIZING TUMORS TO PD-1 IMMUNE CHECKPOINT BLOCKADE (ICB)
Authors: von Roemeling Christina , Yegorov Oleg , Yang Changlin , Russell Rylynn , Carpenter Savannah , Trivedi Vrunda , Bhatia Alisha , Doonan Bently , Golde Todd , Mitchell Duane 
Published: November 2023

Abstract

BACKGROUND
To date, few glioblastoma (GBM) patients have demonstrated clinical benefit from treatment with anti-PD-1 ICB. GBM is notoriously devoid of lymphocytes, signifying that a possible obstacle for effective ICB response may be the limited ability of cytotoxic T-lymphocytes (CTLs) to home to these tumors. CTLs are recruited via long-range signaling mediated by the diffusion of chemokines present in inflammatory environments. Following a comprehensive chemokine screen of clinical tumor specimens, we identified that CXC motif ligand 9 (CXCL9) is notably absent in GBM. To test if GBM reconstitution with CXCL9 could transform these intractable tumors into ICB-responsive, we leveraged AAV gene therapy to generate durable production of this potent lymphotactic signal.

HYPOTHESIS
AAV mediated re-expression of CXCL9 will improve lymphotaxis in GBM, sensitizing these tumors to PD-1 ICB.

METHODS
3-dimensional whole brain fluorescent imaging was performed to characterize the distribution, tropism, and durability of AAV transgene expression in preclinical GBM models. Single-cell RNA sequencing (scRNAseq) and multiparameter flow cytometry was utilized to immunologically profile tumors in response to single and combination treatment. Survival studies with and without lymphocyte depletion were performed to evaluate immunogenic responsiveness of therapy.

RESULTS
Intra-tumor delivery of AAV6 yields stable transduction of tumor-reactive astrocytes, producing a localized, peri-tumoral pattern of transgene signal distribution. Combination therapy increases tumor infiltration by lymphocytes. scRNAseq analyses reveal widespread innate and adaptive immune activation in response to each CXCL9 and PD-1 ICB treatment. Infiltrating CD8 T-lymphocytes demonstrate inflammatory signatures associated with increased effector function, including antigen presentation, cytotoxicity, and TCR signaling. Combination treatment considerably improved overall survival in two distinct GBM models, with durable responses dependent on CD8 T-lymphocyte infiltration.

CONCLUSIONS
This work suggests direct conditioning of the tumor microenvironment by AAV-CXCL9 could potentially overcome a key resistance factor in GBM, sensitizing tumors to immune mediated therapies such as PD-1 ICB.
EXTH-82. THE ROLE OF PTEN AND EPIGENETIC KINOME PROGRAMMING IN EGFR TKI RESPONSE IN GLIOBLASTOMA
Authors: Ziebro Julia , Shelton Abigail , Smithberger Erin , Lin Benjamin , Skinner Kasey , Stamper Allie , Bash Ryan , Furnari Frank , Miller Christopher 
Published: November 2023

Abstract
Glioblastoma (GBM) is the most common brain tumor and standard therapy only extends survival from 12 to 15 months. The receptor tyrosine kinase EGFR is altered in ~60% of GBM, resulting in aberrant activation of downstream pathways, including PI3K, that potentiate tumorigenesis. Though EGFR targeting has been successful in other cancers, clinical trials with EGFR tyrosine kinase inhibitors (TKI) have failed in GBM, in part due to resistance. Trial results suggested that the most common oncogenic EGFR variant, EGFRvIII (vIII), and negative regulator of PI3K signaling, PTEN, were biomarkers of response. To dissect the role of PTEN in GBM tumorigenesis and EGFR TKI response, we utilized vIII-expressing mouse astrocytes with and without functional Pten. Pten loss potentiated tumorigenesis in vitro and in vivo, as proliferation and stemness were significantly increased, and mouse survival was decreased upon implantation as orthoptic allografts. Both RNA-seq and proteomic analysis using multiplex inhibitor beads with mass spectrometry (MIB-MS) showed significantly altered kinome profiles. Pten deleted cells were 5-fold more sensitive to the EGFR TKI neratinib, a drug that induced Pten-dependent modulation of the kinase transcriptome over 48h. This acute transcriptional adaptation implies alteration of the epigenetic landscape. We hypothesized that disruption of enhancer dynamics via BET bromodomain inhibition would improve EGFR TKI durability. We found that cells expressing Pten were 10-fold more sensitive to multiple BET inhibitors, including JQ1, birabresib, and molibresib, and these inhibitors synergized with neratinib to reduce proliferation only in the Pten wild type model. Ongoing work is focused on defining the role of PTEN in maintenance of differential transcriptional and epigenetic programs. We will explore potential mechanistic roles of both the enzymatic and non-enzymatic functions of Pten and characterize its effect on hallmark cancer phenotypes such as proliferation, stemness/self-renewal, and tumorigenesis in the presence and absence of EGFR ± BET inhibitors.