Aggressive Tumor Research Articles

NCOG-41. COMPARATIVE ANALYSIS OF MORTALITY AND SHORT-TERM SIDE EFFECTS IN PATIENTS WITH GLIOBLASTOMA MULTIFORME TREATED WITH TEMOZOLOMIDE VERSUS TEMOZOLOMIDE PLUS BEVACIZUMAB CHEMOTHERAPY

Abstract INTRODUCTION Glioblastoma multiforme (GBM) is a highly aggressive primary brain tumor in adults with limited treatment options and poor prognosis. Temozolomide (TMZ) chemotherapy is the standard treatment for GBM, but alternative therapies have shown limited success. Bevacizumab (BEV), a monoclonal antibody targeting vascular endothelial growth factor (VEGF), is used to restrict GBM growth and spread. This study evaluates the efficacy of combining TMZ with BEV compared to TMZ alone in managing GBM. METHODS A retrospective cohort study was conducted using TriNetX database data, focusing on patients diagnosed with GBM and receiving chemotherapy. Cohorts were defined by treatment: TMZ plus BEV versus TMZ alone. Propensity-score matching balanced baseline characteristics, including demographics and health conditions. Primary outcomes included mortality rates and short-term side effects within the first year of treatment, such as cognitive communication deficits, headache, dizziness, insomnia, and nausea/vomiting. RESULTS After matching, 922 patients were included in each cohort. There were no significant demographic differences post-matching. The mortality rate was higher in the TMZ plus BEV group compared to TMZ alone (51.30% vs. 36.98%, RR: 1.387, 95% CI: 1.249-1.541). However, TMZ plus BEV was associated with a lower incidence of cognitive communication deficits (1.95% vs. 4.34%, RR: 0.45, 95% CI: 0.26-0.779) and dizziness (7.27% vs. 10.52%, RR: 0.691, 95% CI: 0.513-0.93). No significant differences were found in headache, insomnia, or nausea/vomiting rates between the groups. CONCLUSION This study indicates that combining bevacizumab with temozolomide may increase mortality in GBM patients but reduce certain side effects such as cognitive deficits and dizziness. These findings emphasize the need to carefully consider the benefits and risks of different chemotherapy regimens for GBM and highlight the necessity for further research to optimize treatment strategies and improve patient outcomes.

CCRG-03. DETECTION OF HETEROGENEOUS CELL CYCLE ALTERATIONS UPON TMZ CHEMOTHERAPY TREATMENT THROUGH ADVANCED MACHINE LEARNING

Abstract Glioblastoma (GB), the most aggressive central nervous system tumor, is hallmarked by its frequent relapse under alkylating chemotherapy. GB cells frequently exhibit changes in cell cycle phases during TMZ treatment, with a reduction in the G0-G1 phase and an increase in the S and G2 phases. This indicate both tumor cell re-entry into the cell cycle and a TMZ-induced arrest, contributing to resistance and progression. In this study, we leverage dynamic protein abundance of Ki-67, a proliferation marker peaking during S, G2, and M phases, to analyse cellular responses to TMZ in various cell lines and tissue samples. We designed an image-based machine learning approach for pattern recognition to reconstruct and analyse the cell cycle at the single-cell level. Six primary cell lines were characterized through whole-genome DNA, methylation and RNA sequencing. Functional read-outs were performed with large-scale, time- and concentration-dependent TMZ treatments in cell culture and GB-tissue slice models. Our model successfully reconstructed detailed cell cycle stages, showing that untreated cells were predominantly in the G0-G1 phase. TMZ treatment significantly shifted cells toward the S/G2 phase (p < 0.02) in 3 of 6 cell lines and the pseudo-time reconstruction highlighted dose-dependent cell cycle changes. Cell lines with enhanced stem-like features, defined based on epigenetic and transcriptional data signature, showed no cell cycle changes at high TMZ doses (>150µM), regardless the MGMT promoter methylation status. This heterogeneity in cell cycle response emphasizes the complexity of GB and the need for personalized treatments. Our study provides insights into GB MGMT cell cycle alterations and resistance mechanisms that are independent of MGMT methylation status, a known TMZ response biomarker. Therefore, the observed TMZ-induced cell cycle changes may serve as novel biomarkers for assessing treatment response, paving the way for personalized therapeutic approaches.

CTNI-36. THE FEASIBILITY OF USING BORTEZOMIB WITH CHEMOTHERAPY IN ATYPICAL TERATOID/RHABDOID TUMORS

Abstract Atypical teratoid/rhabdoid tumors (ATRTs) are highly aggressive pediatric brain tumors with sensitivity to proteasome inhibitors in preclinical models. We evaluated the feasibility of combining the proteasome inhibitor bortezomib with chemotherapy. Patients aged 0-20 years with newly diagnosed ATRT were enrolled from January 2022 through December 2023. A modified Medical University of Vienna (MUV)-ATRT regimen was used. They were treated with bortezomib of 1.3 mg/m2/dose given intravenously or subcutaneously twice a week for 2 weeks concurrently with 6 cycles of chemotherapy and 2 additional cycles after high-dose chemotherapy. Radiation therapy was given prior to or at the end of chemotherapy. A total of 36 chemotherapy cycles with bortezomib in 6 patients were evaluated. The primary endpoint was grade 3 or higher non-hematologic toxicities. Numbers of cycles with grade 3+ toxicities included: AST/ALT elevation (1), hypokalemia (2), peripheral neuropathy (1), subdural hemorrhage (2), vomiting (2), oral mucositis (3), lung infection (2), urinary tract infection (8), sepsis (3), febrile neutropenia (20). No grade 3+ toxicities were considered bortezomib-related. Three patients completed 8 cycles of bortezomib treatment; 2 patients discontinued the study due to progressive disease after 2 and 4 cycles respectively; 1 patient completed 6 cycles of bortezomib and died of septic shock in complete remission after high-dose chemotherapy. Two patients had a surgical complete resection. Three patients were evaluable for response after bortezomib: 1 partial response and 2 stable disease. Two patients had progression-free survival for 16+ and 22+ months after diagnosis, respectively. Among the 3 patients with progressive disease, 2 had metastatic relapse and 1 had primary and metastatic relapse. There were 4 deaths due to metastatic PD (n=2), septic shock after high-dose chemotherapy (n=1), and septic shock after 2nd line treatment for PD (n=1). We conclude that adding bortezomib to standard and high-dose chemotherapy of ATRT was feasible with the occurrence of grade 3/4 toxicities no more than what was expected with chemotherapy alone. Metastatic relapse remains the major challenge of ATRT treatment.

SURG-31. HYBRID THERAPY FOR NEWLY DIAGNOSED AND RECURRENT GLIOBLASTOMA: STAGED PROCEDURE INTEGRATING OPEN SURGICAL RESECTION WITH LASER INTERSTITIAL THERMAL THERAPY

Abstract BACKGROUND Glioblastoma (GBM) is the most common and aggressive primary malignant brain tumor in adults with a median overall survival (OS) of 15.6 months. Despite advancements, 5-year survival rates have not significantly improved. Laser interstitial thermal therapy (LITT) has been employed to treat both newly diagnosed (nGBM) and recurrent GBM (rGBM) with demonstrable safety and efficacy. Traditionally, LITT has been limited to smaller lesions given physical and thermal constraints. OBJECTIVE We present two case examples of a novel, hybrid treatment approach to GBM, utilizing both surgery and laser ablation as part of a single-staged procedure. METHODS Two geriatric (>65 years) patients with nGBM or rGBM were treated with surgical resection followed by LITT the subsequent day. Both patients underwent preoperative magnetic resonance imaging (MRI) showing multifocal disease with a dominant component, causing mass effect in the second case, and an unresectable component. RESULTS The first case underwent surgical resection of a large, multicentric rGBM in the parieto-occipital region, followed by LITT of an unresectable lesion in the inferior temporal gyrus. The second patient underwent surgical resection of the dominant temporal lobe component, and LITT of the insular component. Neither patient had intraoperative or ablation complications. Both patients had stable postoperative neurological exams and were discharged on the day after ablation, with no new deficits at follow-up. CONCLUSION The prognosis for GBM remains dismal despite significant research and attempts at advancements in patient management. Surgical resection is a critical component of the GBM treatment paradigm. However, surgery alone is not sufficient in many patients. LITT has shown promise for improving GBM outcomes, mainly due to its minimal invasiveness, enhanced immune responses, BBB disruption, and cytoreductive potential. We demonstrate a novel, hybrid approach to GBM using hybrid surgical resection and LITT in a single-staged procedure to overcome traditional constraints of LITT.

CNSC-23. CROSSTALK BETWEEN STROKE AND GLIOMA: ISCHEMIA-INDUCED NEURONAL ACTIVATION ON GLIOMA INFILTRATION

Abstract Glioblastoma (GBM) is an aggressive primary brain tumor associated with dismal survival rates. GBM is difficult to treat due to its ability to invade neighboring brain regions, rendering complete surgical resection nearly impossible. Throughout tumor progression, several pathological changes occur in the tumor microenvironment (TME) including increased neuronal hyperactivity. Interestingly, these pathological features also occur in stroke, a leading global cause of death and disease burden. Clinical evidence from large cohort studies reveals a 10% risk of brain tumor development in stroke patients, suggesting a link between these two diseases. However, the intricacies of their association and whether stroke poses a long-term risk for GBM is unclear. To investigate this, we have developed innovative stroke-glioma mouse models to recapitulate and delineate the interrelationship between these two diseases. Our data using these models indicate a substantial increase in tumor growth and infiltration towards the infarct using both human GBM-patient derived glioma cells in immunodeficient mice as well as in immunocompetent de novo mouse GBM. Further, spatial manipulation of stroke and glioma induction revealed that glioma cells preferentially invade the contralateral hemisphere towards the stroke lesion compared to control. This suggests stroke-induced changes may trigger glioma cell infiltration. Histological analysis of the TME shows increased neuronal activity specifically excitatory neuron synaptic marker expression in the leading edge of glioma post-stroke compared to control. Overall, stroke induction may promote tumor growth and infiltration by modulating the TME through increasing excitatory neuronal activation. Together, this study aims to deepen our understanding of the influence of stroke on gliomas, paving the way for invaluable insights essential for identifying at-risk patients and the development of potential treatments for affected patients.

EXTH-78. A NOVEL BISPECIFIC S100A4/TFR ANTIBODY TO REPROGRAM THE GLIOMA TUMOR MICROENVIRONMENT AND TARGET GLIOMA STEM CELLS

Abstract GBM (glioblastoma) is the most common and aggressive primary brain tumor in adults. While immunotherapy is a promising treatment modality for GBM, most clinical trials have thus far only provided a modest benefit to GBM patients. We propose that enhancing the efficacy of immunotherapy for GBM requires approaches that increase T cell infiltration and reprogram the myeloid cells to a more pro-inflammatory state. S100A4 is a major regulator of stemness, epithelial-mesenchymal transition, and a critical regulator of immune suppressive myeloid and T cell phenotypes in GBM. Targeting S100A4 in either glioma or stromal cells is sufficient to reprogram the tumor immune landscape and extend survival of glioma bearing mice, indicating that S100A4 is a promising immunotherapy target. We recently developed a S100A4 blocking monoclonal antibody; however, this antibody does not cross the blood brain barrier (BBB) efficiently to confer significant therapeutic benefit, limiting its efficacy in treating GBM. To overcome this challenge, we generated a bispecific S100A4-TfR antibody (BsA) that allows robust BBB penetration, and tested this in a pre-clinical syngeneic, orthotopic mouse model of GBM. Using ELISA, confocal immunofluorescent microscopy, flow cytometry, and bulk RNA sequencing, we report that systemic administration of the S100A4-TfR BsA results in increased immune cell infiltration with a preferential increase in CD4 T cell infiltration, and potent immune remodeling of the tumor microenvironment to a more pro-inflammatory state. Furthermore, the BsA is taken up by glioma cells intracellularly, which is correlated with depletion of intracellular S100A4 and decreased nuclear SOX2 localization, which would reduce stemness of glioma cells. Functionally, in vitro BsA treatment of primary glioma cell cultures shows decreased S100A4 expression, proliferation, and self-renewal. Our results suggest that S100A4-TfR BsA is a novel dual activity inhibitor to simultaneously reprogram the GBM immune landscape and reduce glioma stemness.

IMMU-62. INVIGORATING EFFECTOR IMMUNE CELLS WITH HIGHLY SELECTIVE IL-2R AGONISTS AND POTENTIAL SYNERGY WITH TUMOR TARGETING THERAPEUTICS FOR TREATMENT OF GLIOBLASTOMAS

Abstract Glioblastoma (GBM) is an aggressive brain tumor with a median overall survival (mOS) of 14 months. Treatment options are limited with no new approved therapies over the past 3 decades and no standard of care for a majority of patients (> 90%) who experience recurrence. GBM has a highly immune suppressive tumor microenvironment (TME) comprising of myeloid derived suppressor cells (MDSCs) and tumor associated macrophages (TAMs) that are capable of suppressing the activity of anti-cancer CD8+ T and NK cells. We have engineered highly selective IL-2 superkines (IL-2SK) that preferentially expand and activate CD8+ T and NK cells with limited effects on immune suppressive regulatory T cells (i.e., Tregs). MDNA11 is an IL-2SK -albumin fusion protein designed to increase half-life and promote tumor accumulation. MDNA223 is a bi-functional anti-PD1-IL-2SK designed to stimulate effector immune cells while preventing immune exhaustion. MDNA11 and MDNA223 extended survival of mice harboring orthotopic GBM tumors with accompanying increase in CD8+ T and NK cells within the TME. When patient-derived GBM tumor explants were treated with MDNA11 and MDNA223 ex vivo, there was clear evidence of activation among resident CD8+ T cells characterized by increased levels of intra-cellular Granzyme B responsible for tumor cell killing. There was also increased release of soluble Fas ligand and granulysin, consistent with an activated anti-tumor immune response within the TME. Ongoing studies include in depth immune profiling to further understand the mechanism of MDNA11 and MDNA223 in GBM as well as to test potential synergy with tumor targeting therapeutics and other treatment modalities capable of eliciting immunogenic cell death.

BIOS-06. MACHINE LEARNING MODEL INDEPENDENTLY IDENTIFIES CLINICAL FEATURES ASSOCIATED WITH WILD-TYPE GLIOBLASTOMA VERSUS MUTANT GRADE 4 ASTROCYTOMA

Abstract BACKGROUND Glioblastoma (GBM), the most common and aggressive primary brain tumor in adults, presents significant clinical challenges due to its invasive nature and high recurrence rates. Understanding the clinical demographic factors associated with IDH wild-type (IDH-wt) versus mutant grade 4 astrocytoma (IDH-Mut) is critical for prognosis and treatment strategies. This study aimed to utilize a novel machine learning method to identify key clinical and demographic factors linked to IDH status. METHODS The Cancer Imaging Archive dataset included 617 patients but required preprocessing and cleaning. The cleaning process ensured data completeness and consistency by removing non-relevant variables like date and time, resulting in 20 potential predictors and 317 observations. A random forest model using Gini impurity score was built to classify patient IDH status. The dataset was split into a training set (two-thirds) and a test set (one-third). A variable importance plot identified significant variables based on the mean decrease in the Gini index. RESULTS Our machine learning model achieved 98% accuracy on the test set, outperforming the previously published model of 80% accuracy. A variable importance plot identified age at diagnosis, gender, ethnicity, and race as key predictors of IDH status, with age being the most important. Age was the most important predictor, but race (Caucasian) and ethnicity (not Hispanic or Latino) were also significant. CONCLUSIONS We present a highly accurate machine learning model for differentiating glioma IDH molecular status based only on patient clinical and demographic factors; improving upon prior published models. Future work will use a generalized logistic model to explore variable interactions and predict IDH-wt versus IDH-Mut status. These steps are vital for enhancing predictive accuracy and supporting personalized treatment strategies. Furthermore, we will define associations and interactions between these variables with other biological and therapeutic variables in predicting clinical outcome.

INNV-27. TEMOZOLOMIDE FOR PATIENTS WITH AGGRESSIVE PITUITARY TUMORS: A CASE SERIES

Abstract BACKGROUND Pituitary adenomas are often effectively managed with medical therapy, surgery, and radiation therapy. However, up to 15% of pituitary neoplasms exhibit rapid growth, invasive behavior, or, rarely, metastasize despite optimal standard treatments. Temozolomide is associated with a survival benefit for patients with these aggressive pituitary tumors. METHODS We present a case series of 8 patients with an aggressive pituitary tumor (APT) or pituitary carcinoma (PC) treated with temozolomide. RESULTS Eight patients (3 female, median age at diagnosis 44) with APT (n=6) or PC (n=2) were treated. A variety of pituitary tumor types were represented (1 prolactinoma, 5 corticotroph adenomas, 1 gonadotroph adenoma, 1 thyrotropinoma). Prior to temozolomide initiation, patients underwent a median 5 treatments including medical management (n=4), surgery (n=7), radiation therapy (n=7). Temozolomide was started at median 3.5 recurrence. Median treatment duration was 6 cycles (n=6, 150-200 mg/m2 days 1-5, 28-day cycles; n=1, 75 mg/m2, days 1-21, 28-day cycles). Seven patients experienced progression after temozolomide treatment, median progression-free survival (PFS) was 4 months. One patient remains on treatment, progression-free at 5 months. MGMT methylation status was assessed for 3 tumors. Among 2 patients with MGMT promoter methylated tumors, PFS was 4 months for one patient, the other remains on treatment. For one patient with MGMT promoter unmethylated corticotroph adenoma, PFS was 9 months. No ≥ grade 4 toxicities were noted. Most common toxicities were nausea (n=5), thrombocytopenia (n=3), and fatigue (n=2). CONCLUSION In this group of heavily pretreated patients, temozolomide monotherapy was well-tolerated and associated with median PFS of 4 months. Interestingly, PC patients had longer PFS at 9 months and 24 months. Our findings support use of single-agent temozolomide chemotherapy for patients with APT/PC, but further prospective analysis is needed to identify patients more likely to benefit from treatment and optimal timing of chemotherapy initiation.

IMMU-17. ADENOSINE DEAMINASE ACTING ON RNA (ADAR) SILENCES TUMOR-INTRINSIC INTERFERON RESPONSE IN DIFFUSE MIDLINE GLIOMA

Abstract INTRODUCTION Diffuse midline glioma (DMG) is the most aggressive primary brain tumor in children and is currently incurable. Clinical trials using immune checkpoint blockade (ICB) therapy have failed to show efficacy due to multifactorial mechanisms including limited lymphocyte infiltration, low immune checkpoint (IC) expression, and a low mutational burden. Adenosine deaminase acting on RNA (ADAR) is an RNA editor, which limits anti-tumor immunity by editing/preventing the sensing of endogenous double-stranded RNA (dsRNA). We have found that ADAR protein levels are significantly elevated in DMG patients, suggesting that ADAR’s immune-silencing function is relevant to DMG immune suppression. The onco-histone driver H3K27M promotes epigenetic dysregulation in DMGs, de-suppressing retroelement transcription, a major source of endogenous dsRNA. By inhibiting ADAR, we expect that the increased levels of dsRNA will stimulate intracellular type-1 interferon (IFN) responses, induce chemokine secretion, and promote antitumor CD8+ cytotoxicity. METHODS Human DMG cells and patient-derived glioma spheres were treated with silencing RNA to transiently knockdown (KD) ADAR levels for assays involving in vitro viability and proliferation. Affected pathways were identified using immunoblotting and quantitative PCR. RESULTS Our data shows that ADAR protein levels are elevated in DMG patient proteomic datasets and cell lines. ADAR-depleted patient-derived DMG cell lines exhibit significantly less proliferation compared to control siRNA and ADAR-depleted hTERT-astrocytes (Mann-Whitney test, P-value <0.0001, ****). CONCLUSION Our results demonstrate that DMG tumor cells have an ADAR selective dependency in vitro. In ongoing studies, we aim to determine if ADAR-depletion improves in-vivo survival in both immunodeficient and immunocompetent models in combination with immunotherapies against DMG.

STEM-03. TARGETING F-ACTIN DYNAMICS OF GLIOBLASTOMAS TO OVERCOME THERAPY RESISTANCE: IMPACTS ON DNA REPAIR AND GLIOMA STEM CELL PHENOTYPE

Abstract Glioblastoma (GBM) is a highly aggressive brain tumor with high recurrence and resistance to therapies. The F-actin cytoskeleton in GBM is related to cell invasion and the glioma stem cell (GSC) phenotype, affecting self-renewal and migration. Our research identifies a novel role for the F-actin pathway in DNA repair, impacting genomic stability and contributing to therapy resistance. Understanding F-actin’s role is crucial for developing targeted strategies to improve GBM treatment outcomes. This study examines the effects of pharmacological F-actin depolymerization on reversing resistance to ionizing radiation (IR) and temozolomide (TMZ) in GBM spheroids. We established resistant sublines of GBM U87-MG cells through IR and TMZ cycles, observing significant resistance increases via MTT assays. Also, resistant cells had enhanced spheroid formation capacity, with higher size and proliferation. Alterations in DNA repair and F-actin pathway were observed, with intensified and disorganized F-actin polymerization and efficient repair in resistant cells. Elevated expression of stemness markers (Nestin, CD133, and CD44) indicated a GSC-like phenotype in resistant cells, corroborated by increased tumorigenicity and de novo spheroid formation. These markers were further enhanced by DNA damage. Treating cells with actin polymerization inhibitors reduced resistance to TMZ and IR, partly due to impaired DNA repair capacity. Additionally, F-actin disassembly affected stemness marker expression, reinforcing the link between cytoskeletal dynamics and the GSC phenotype. Our findings suggest that F-actin dynamic is crucial for resistance in GBM. Targeting F-actin could resensitize recurrent GBM tumours by diminishing DNA repair capabilities and affecting the GSC-like phenotype, offering new therapeutic avenues.

CNSC-47. SENOLYTICS ERADICATE SENESCENT MICROGLIA IN THE BRAIN PARENCHYMA AND IMPROVE SURVIVAL IN OLDER ADULT MICE WITH GLIOBLASTOMA

Abstract BACKGROUND Glioblastoma (GBM) is the most common aggressive primary malignant brain tumor in adults with a poor median survival rate. Despite the aggressive standard of care treatment combining surgical resection, chemo-, and radio-therapy, the median overall survival (OS) is only ~15-18 months. Progressively increasing subject age is inversely associated with GBM patient OS such that older adults tend to have significantly worse survival outcomes compared to younger counterparts. Senescent cells accumulate in the body during progressive aging and contribute to worse outcomes in older adult mice with GBM. Senolytics are pharmacologics that cause senescent cells to undergo cell death. OBJECTIVE To comprehensively profile the treatment effect of senolytics combined with or without immunotherapy in mice with GBM across the lifespan. METHODS Young 7-9- and older adult 97-104-week-old wild-type (WT; C57BL/6) and 110-130-week-old INK-ATTAC mice with or without intracranial SB28 cells were treated with or without brain radiation (RT), PD-1 mAb, and an IDO enzyme inhibitor with the senolytics, dasatinib + quercetin, or the AP compound that induces p16INK4A+ senescent cell death in INK-ATTAC mice (n=5/group). The quantification of beta-galactosidase positive cells by flow cytometry was performed on brain-resident neurons, astrocytes, oligodendrocytes, microglia, as well as dendritic cells, macrophages, neutrophils, T cells in the tumor and non-tumor bulk mass. Overall survival was also evaluated. RESULTS Senolytics or AP compound treatment both decrease beta-galactosidase positive microglia in the older adult brain with GBM (p<0.05). Combining radio- and immuno-therapy with senolytics improves overall survival of older adult mice with intracranial GBM (p<0.05). CONCLUSIONS Our ongoing work aims to understand how senescent microglia affect neuronal health and function in the older adult brain with GBM. KEYWORDS Glioma, senescence, senolytic.

EXTH-17. THERAPEUTIC EFFICACY OF B7-H3 CAR T CELLS IN PEDIATRIC HIGH-GRADE GLIOMAS WITH H3G34R/V MUTATION

Abstract Pediatric high-grade gliomas (pHGGs) are aggressive brain tumors responsible for significant childhood mortality. These tumors often carry mutations in the H3F3A gene, which encodes histone H3.3 proteins. However, current treatment options are limited, underscoring the need for innovative approaches. Chimeric antigen receptor (CAR) therapy, which was successful in treating certain childhood cancers, holds promise for pHGGs with H3G34R/V mutation. In this study, we examined the expression of B7-H3 in patient tumor specimens and various pHGG cell lines with H3G34R/V mutation. Data revealed substantial B7-H3 expression, confirming its potential as a therapeutic target. Co-culturing B7-H3 CAR T cells with H3G34R/V mutated KNS42 and SJ-HGG-X42 cells led to significant increase in the expression of markers associated with T cell activation (IL2, IL6, IF-γ, TNF-α) and immune responses involving cytolytic cells (Granzyme A, B, Perforin) and elevated levels of exhaustion markers (2B4, PD1, Tim3, Lag3) in comparison to mock-treated cells. We evaluated the capability of B7-H3 CAR T cells for cytolytic activity against KNS-42 and SJ-HGG-X42 cells through in vitro testing. Our results after 72 hours of co-culture revealed a strong killing potential of B7-H3 CARs against B7-H3 positive KNS-42 and SJ-HGG-X42 cells, while minimal or no killing was observed on B7-H3KO KNS-42 and B7-H3 negative MDA MD 453 cells. In vivo efficacy of B7-H3 CAR T cells in an orthotopic mouse xenograft model implanted with KNS-42 cells. B7-H3 CAR T cell treated mice showed a marked reduction in tumor burden and a substantial improvement in survival in contrast of CD19-CAR T cell treated control group. Lastly, we have developed a novel In-Utero Electroporation (IUE) immune-competent mouse model of pHGGs with H3G34R/V mutation, that enables exploration of the impact of immune suppressive tumor microenvironment on CAR T cells efficacy. In conclusion, B7-H3 emerges as a promising therapeutic target, and CAR T cells display encouraging functionality within the context of pHGGs with H3G34R/V model.

EXTH-29. EVALUATION OF THE ANTITUMOR EFFECT OF A CHEMOTHERAPY-LOADED DEVICE FOR THE TREATMENT OF PRIMARY BRAIN TUMORS

Abstract Glioblastoma (GBM) is the most frequent and aggressive primary brain tumor in adults. Tumor recurrence is therefore inevitable, and median survival is just over 14 months. Currently available treatments are inadequate and do not provide optimal tumor control. We believe that treatment localized directly at the tumor site will eliminate a greater number of infiltrating tumor cells while significantly reducing systemic toxicity. For this project, we are collaborating with a team specializing in bioengineering, who have produced a biomaterial enabling the gradual release of various chemotherapeutic agents. Our aim is to use this biomaterial to deliver chemotherapeutic agents to the tumor site through the surgical cavity. Cell-based assays were carried out using glial tumor cells in the presence of the biomaterial containing chemotherapeutics. A survival study was realized with the Fischer F98 rat model, which underwent partial tumor resection followed by injection of biomaterial containing chemotherapy. Histological studies of brains and resected tissues were also carried out to assess the effect of the biomaterial on the brain environment. In vitro assays showed a strong cytotoxic effect against glial tumor cells at 24h, 48h and 72h of biomaterial-drug incubation. The combination of two chemotherapeutic agents showed the best cytotoxic effect on glial tumor cells. We also performed a partial tumor resection and insertion of the chemotherapy-loaded biomaterial into the surgical cavity of the F98 glioma bearing rat. Similar to in vitro studies, the combination of two antineoplastic agents shows a significant improvement in animal survival. In conclusion, the in vitro and in vivo results of this study show that the combination of chemotherapy has the greatest antitumor effect. We hope that these exciting results will lead to the development of a new treatment for patients with glioblastoma and potentially other diseases where complete tumor resection is impossible.

PATH-03. SPATIAL-RESOLVED METABOLOMICS ANALYSIS IN HISTOLOGICAL AND MOLECULAR GLIOBLASTOMAS USING A MOF/MXENE-ASSISTED LDI-MSI PLATFORM

Abstract Glioblastoma (GBM) is a highly aggressive primary brain tumor encompassing both histological and molecular subtypes. Metabolites within the tumor microenvironment play critical roles in regulating tumor behavior and response to therapy. Understanding their spatial distribution provides valuable insights for diagnosis and treatment. We investigated metabolite patterns of histological GBMs (hist-GBMs) and molecular GBMs (mol-GBMs) by developing a novel MOF/MXene platform for enhanced surface-assisted laser desorption/ionization mass spectrometry. Utilizing this platform, we analyzed the metabolomes of three hist-GBMs and three mol-GBMs. Our platform exhibited exceptional sensitivity, repeatability, and stability in detecting metabolite molecules. Analysis of the metabolomes revealed distinct spatial distributions and concentrations of various metabolites, including carbohydrates, amino acids, organic acids, nucleotides, and their precursors. Notably, certain metabolites such as TG(15:0/20:3n6/20:5(5Z,8Z,11Z,14Z,17Z)), PG(20:3(6,8,11)-OH(5)/i-21:0), and SM(d20:1/20:3(6,8,11)-OH(5)) were significantly enriched in hist-GBMs compared to mol-GBMs, while others, including lithocholic acid glycine conjugate, PE(P-16:0/14:1(9Z)), and CE(11:1D5), exhibited higher peak intensity in mol-GBMs. Overall, our findings underscore the existence of unique metabolomic signatures distinguishing hist-GBMs from mol-GBMs. In conclusion, heterogeneous metabolite distributions among hist-GBMs and mol-GBMs were revealed by our novel MOF/MXene assisted LDI-MSI platform, and unique metabolic signatures were identified. Advanced metabolomics analysis holds promise for precise biomedical diagnostics and individualized therapeutic strategies in GBMs.

DISP-17. OUTCOMES, CLINICAL AND MOLECULAR CHARACTERISTICS OF HISPANIC PATIENTS WITH IDH WILDTYPE GLIOBLASTOMA

Abstract BACKGROUND Knowledge about outcomes in Hispanic patients with gliomas is scant and mainly derived from tumor registries. IDH wild-type glioblastomas (GBM) are the most common and aggressive malignant primary brain tumor. Hispanics account for 19% of US population, reaching 29% in Florida and 65% in Miami-Dade County. As a reference center for GBM serving the community of South Florida we provide care for many Hispanic patients. Herein, we aim to describe the clinical and molecular features, including RNA seq analysis of Hispanic vs non-Hispanic patients with IDH wild-type GBM. METHODS Retrospective study of adult patients with diagnosis of IDH Wild-type Glioblastoma, who had NGS testing, treated at University of Miami. RESULTS 179 patients were included, 63 (35%) were Hispanic. 41 (65%) of Hispanic patients were males as compared to 65 (56%) of the non-Hispanics. Median age at diagnosis was 54 years (45-67) for the Hispanic vs 62 (54-72) years for non-Hispanic, p=.002. With a median follow up of 17 months (CI 95% 14-19), median overall survival for Hispanic patients was 22 months (18-25) and 23 months (18-28) for non-Hispanics, p=.99. 42 (23%) patients were enrolled in clinical trials, of whom 21 (50%) were Hispanic, meaning 33% of Hispanic patients enrolled. The molecular characteristics from these patients by next-generation sequencing, including RNA seq, are being analyzed. CONCLUSIONS In our series of IDH wild-type Glioblastomas, Hispanic patients were significantly younger at diagnosis compared to non-Hispanic patients, but there were no differences in overall survival. 33% of Hispanic patients were enrolled in clinical trials. As the latest growing ethnic group in the USA, major efforts have to be made to better understand the disease characteristics and outcomes of this particular population. To our knowledge this will be the first report of the molecular characteristics by NGS from Hispanic patients with GBM.

RADT-06. IDENTIFICATION OF NEW RADIATION RESPONSE PREDICTOR GENES FOR GLIOBLASTOMACRUCIAL CONTRIBUTION OF THE LUNATIC FRINGE GENE (LFNG)

Abstract Glioblastoma (GBM) is adults’ most common aggressive primary intracranial tumor. The current standard of care involves maximal safe surgery followed by radiochemotherapy. OBJECTIVE our study was to identify genes that predict response to radiochemotherapy. MATERIALS AND METHODS We collected molecular and clinical data, including primary glioma mRNA expression, from two international online databases - TCGA and CCGA. A total of 76 cases were examined, with 41 patients in the TCGA cohort and 35 in the CCGA cohort. The patients were divided into two groups before assessing the data. Group 1 included patients who were alive at the time of the analysis, and Group 2 included patients who had passed away. Then, we performed a single-center Moroccan transcriptomic study involving 28 cases to assess the impact of the individualized gene in our environment. RESULTS The following genes, namely SRPX, S100A16, LFNG, CD5, CMBL, and TCTN2, are among the top genes co-overexpressed in TCGA and CGGA patients. We conducted a multivariate COX survival test, taking into account known prognostic clinical parameters, and found that the LFNG gene is the only marker of poor prognosis independent of other clinical markers in TCGA and CGGA patients treated with radiotherapy. Our results indicate that patients who overexpress LFNG have elevated IFNg levels and low granzyme B levels, while the levels of perforin and granzyme A remain unaffected by LFNG variation. Furthermore, our results demonstrate positive correlations between LFNG gene expression and four immune checkpoints (PD1, PDL1, CTLA4, and VISTA), but negative correlations only with TIM3. CONCLUSION Our findings suggest that LFNG could serve as a useful biomarker for identifying patients with poor prognosis and that LFNG expression may be associated with specific immune checkpoint expression patterns. These results have important implications for the development of new therapeutic approaches in the treatment of TCGA and CGGA patients.

DNAR-06. EPITRANSCRIPTOMIC TRNA MODIFICATIONS TARGETING ADENOSINE (A) AT POSITION 37 IN GBM

Abstract GBM stands as the most aggressive brain tumor in adults. The median overall survival is less than 2 years despite conventional treatments. Recent advancements in DNA analysis have delineated the molecular characteristics of gliomas, leading to revisions in the WHO classification based on DNA profiles. However, the role of RNA modifications, epitranscriptomics, remains poorly understood in glioma. In this study, we underscore the significance of tRNA modifications targeting adenosine at position 37 in GBM. Transfer RNA isopentenyl transferase 1 (TRIT1) is identified as an isopentenyl transferase catalyzing the conversion of A into i6A at position 37 of tRNA, a nucleotide adjacent to the anticodon region. Additionally, i6A is further modified to 2-methylthio i6A (ms2i6A) by cyclin-dependent kinase 5 regulatory subunit associated-protein 1 (CDK5RAP1) within mitochondrial tRNA. Analysis of TCGA data reveals elevated TRIT1 mRNA expression levels in GBM compared to non-tumor samples. Furthermore, a low expression group of TRIT1 in gliomas demonstrates improved survival outcomes according to data from the CGGA, implicating TRIT1 in glioma progression. Functional assays involving TRIT1 knockdown in human GBM cell lines result in decreased cell viability, indicating its functional significance. Moreover, our data suggest that this phenotype may be mediated through translational control of selenoprotein W (SEPW1) via tRNA^(Ser)Sec modification. GO analysis of TRIT1 and SEPW1 in TCGA data further supports this proposed mechanism. At position 37 of tRNA, we also found that CDK5RAP1 in mitochondrial tRNAs is indispensable for sustaining glioblastoma initiating cell (GIC)-related traits. CDK5RAP1 maintains the self-renewal capacity, undifferentiated state, and tumorigenic potential of GICs, independent of translational control of mitochondrial proteins. Notably, CDK5RAP1 abrogates the antitumor effect of i6A by converting i6A to ms2i6A and shields GICs from excessive autophagy triggered by i6A. This work underscores the critical role of tRNA modifications in glioma pathogenesis. We will report these findings alongside RNA modification profile data and clinical data from glioma patients.

IMMU-22. TWIST1-MEDIATED ENDOTHELIAL PLASTICITY DRIVES GLIOBLASTOMA RESISTANCE TO CAR T IMMUNOTHERAPY

Abstract Glioblastoma (GBM) is the most common and most aggressive malignant primary brain tumor in adults. Among the most lethal human malignancies, GBM is highly resistant to cytotoxic treatments and molecularly targeted therapies, and also generally refractory to T cell–based immunotherapies, largely due to their immunologically cold nature, i.e., characterized by a paucity of tumor T cell infiltrates that result from the immunosuppressive microenvironment. Here, we identify a distinct mechanism driven by spatiotemporal interaction of leukocytes with tumor stromal cells, namely, mesenchymal-like population of endothelial cells (ECs) form an immunosuppressive vascular niche that regulates macrophage polarization and induces GBM resistance to CAR T immunotherapy. Our single-cell transcriptome analyses of human and mouse GBM tumors identify a subpopulation of ECs acquire robust immunosuppressive phonotypes to drive alternative macrophage polarization. These ECs are spatially localized proximately to immunosuppressive macrophages and selectively express Twist1. Furthermore, we reveal a Twist1/SATB1-mediated sequential transcriptional activation mechanism, through which Twist1+ tumor ECs produce osteopontin to locally promote immunosuppressive macrophage phenotypes. Genetic or pharmacological ablation of Twist1 reverses macrophage-mediated immunosuppression and enhances T cell infiltration and activation, leading to reduced GBM growth and extended mouse survival. Importantly, pharmacological inhibition and lipid nanoparticle-mediated targeted inactivation of Twist1 overcome GBM resistance to Egfrviii CAR T cell immunotherapy. Thus, these findings uncover a spatially restricted mechanism controlling vasculature-mediated tumor immunity and suggest that targeting endothelial Twist1 may offer exciting opportunities for GBM immunotherapy.

CSIG-15. ACROLEIN INDUCES THE MIR-30A-5P/NCAM AXIS VIA THE AKT/GSK3Β/Β-CATENIN PATHWAY, PROMOTING GLIOMA PROGRESSION

Abstract Glioblastoma (GBM), the most aggressive brain tumor, exhibits resistance to treatment and thrives in low-oxygen (hypoxic) environments, leading to the accumulation of reactive oxygen species (ROS). Hypoxia activates the hypoxia-inducible factor (HIF)-1α pathway, enhancing tumor malignancy. Acrolein, a reactive aldehyde produced during lipid peroxidation in hypoxia, induces toxicity through DNA damage, inflammation, mitochondrial dysfunction, and oxidative stress. Our previous study found elevated acrolein levels in hypoxic glioma cells and linked acrolein-induced DNA damage (Acr-dG) with poor GBM prognosis. However, the role of acrolein in GBM progression remains unclear. This study aims to elucidate the impact of acrolein on GBM. In vitro experiments demonstrated acrolein production under hypoxia, which increased glioma cell migration and spheroid formation. RNA sequencing identified five affected pathways: cell adhesion molecules, PI3K-AKT signaling, ECM-receptor interaction, MAPK signaling, and neuroactive ligand-receptor interaction. Acrolein downregulated NCAM (neural cell adhesion molecule) via the miR-30a-5p-AKT-GSK3β/β-catenin axis in GBM cell lines and patient-derived cells. Overexpressing NCAM reduced cell migration and spheroid formation. Lower NCAM levels in GBM tissues correlated with poor patient survival. This study suggests the potential of NCAM as a therapeutic target for GBM and provides insights into early detection and treatment strategies for this malignancy.