tbuckley/cabot-search huggingface dataset:
DDDR-48. EZH2 INHIBITION AS A POTENTIAL THERAPEUTIC AVENUE IN THE TREATMENT OF MENINGIOMA
Authors: Joshua Casaos, Jeremie Vitte, Travis Perryman, Maya Harary, Shilp Shah, Brian Na, Richard Everson, Marco Giovannini
Journal: Neuro-Oncology (2024)

Abstract INTRODUCTION High grade meningiomas provide challenges to treatment as these neoplasms are more likely to recur, exhibit invasion of brain parenchyma, and result in decreased long term survival. Recent works demonstrate the epigenetic modifier, EZH2, to be increased in higher grade meningiomas, and to correlate with poor survival. The selective targeting of EZH2 has shown promise in other malignancies with overexpression of or gain-of-function mutations in EZH2, leading to promising findings. Here we sought to investigate the effect of EZH2 inhibition on meningioma cell growth and viability, using a panel of in vitro models. METHODS Human immortalized meningioma cell lines, mouse meningioma cell lines and a panel of human primary cell cultures with varying baseline protein expression of NF2, SMARCB1, and EZH2, were selected for investigation. Cells were treated with several selective small molecule inhibitors of EZH2. Cell proliferation, cell cycle and cell death processes were assessed. RNAseq was used to assess transcriptional changes in response to EZH2 inhibition. Western blots were used to assess protein changes in response to EZH2 inhibition. RESULTS EZH2 inhibition significantly impairs meningioma cell proliferation, at varying IC50s, in all cell lines and primary cultures tested, utilizing a panel of EZH2 inhibitors. EZH2 inhibition resulted in significantly decreased colony formation in a high-grade cell line. Furthermore, EZH2 inhibition results in a reduction of Ki67+ cells, induction of cell cycle arrest, and apoptosis. Similar grouping of differential gene expression in immortalized cell lines and primary cell cultures is observed across cell lines and primary cell cultures, after EZH2 inhibition. CONCLUSION Our work demonstrates that EZH2 inhibition results in growth inhibition, cell cycle arrest, and cell death, across all cell lines, and cell cultures tested. Futhermore, modulation of protein levels of the EZH2 target H3K27 is observed upon treatment. RNA changes are broad and involve cell proliferative and migratory processes. This work provides the framework for further investigation of EZH2 inhibition in meningioma.
EPID-03. BRAIN CANCER IN AFRICA: UNCOVERING THE HIDDEN EPIDEMIC THROUGH A SYSTEMATIC REVIEW
Authors: Olivier UWISHEMA
Journal: Neuro-Oncology (2024)

Abstract BACKGROUND Cancer poses a significant public health threat globally, leading to substantial morbidity. While malignancies were previously thought to predominantly affect high-income countries, numerous studies indicate an increasing burden on resource-limited nations. Brain cancer, in particular, can be devastating due to treatment challenges and high mortality rates. Africa, with its resource-limited countries, must establish proper healthcare infrastructure to reduce cancer incidence and enhance patient survival. Additionally, the scarcity of data in this area in Africa presents a challenge to effective management. This study aims to explore the available evidence on the epidemiology and etiology of brain cancer in resource-limited African countries, highlighting the growing burden and advocating for further research. MATERIALS AND METHODS We conducted a systematic review by searching PubMed and Scopus using a predefined approach. Additionally, we utilized the Global Cancer Observatory and Global Burden of Disease databases. Studies reporting on brain cancer epidemiology, etiology, and impact in Africa were included, with the level of evidence assessed according to Centre for Evidence-Based Medicine guidelines. RESULTS Brain cancer presents a significant healthcare challenge in many African developing nations due to poor survival rates, inadequate funding and resources for reporting, identification, and treatment, as well as limited comprehensive research. CONCLUSION This study underscores the urgent need to address brain cancer as a major public health crisis in Africa. Improved treatment options and access to screening are essential to mitigate the disease burden. Thus, substantial and comprehensive research on brain cancer within Africa is crucial for effective management and reducing associated morbidity and mortality.
EXTH-33. COMBATING TUMOR HETEROGENEITY IN GLIOBLASTOMA WITH A NOVEL CAR-BASED PLATFORM
Authors: Daniel Wilkinson, Emily Lerner, Peter Fecci
Journal: Neuro-Oncology (2024)

Abstract Tumor heterogeneity is a major hindrance impeding success of antigen targeting immunotherapies, such as chimeric antigen receptor (CAR) T cells, in solid tumors. CAR T cells engineered to target EGFRvIII, IL13Rα2, and HER2 have mostly failed clinically to treat glioblastoma, because these antigens are typically only expressed on a subset of a tumor cells within a patient. Thus, finding a surface target that more universally characterizes tumor cells will likely be critical if antigen-specific immunotherapies are to succeed in glioblastoma and other solid tumors. Recently, we uncovered a mechanism whereby CD8 T cells can directly kill tumor cells independently of tumor-expressed major histocompatibility complex (MHC)-I. We found this mechanism to be dependent on NKG2D expression on T cells and NKG2D ligand (NKG2DL) expression on tumor cells. Interestingly, NKG2DL expression was not limited to MHC-I-deficient tumor cells, nor was it limited to gliomas, but NKG2DL expression characterized a variety of solid tumor types. Therefore, NKG2DL is potentially an ideal target for immune-based therapy. Here, we developed a bi-specific fusion protein comprised of the extracellular domain of NKG2D linked to an anti-CD3scFv. Thus, T cells will be redirected to target NKG2DL-expressing tumor cells. We have termed this fusion protein Bi-specific Engagers without Antigen Requirements (BEAR). To ensure local, intratumoral delivery of BEAR, we engineered an EGFRvIII-targeting CAR T cell to secrete BEAR (VIII CAR Engineered with BEAR; VIII “CARE-BEAR”). VIII CARE-BEAR demonstrated potent tumor kill in both in vitro and in vivo tumor heterogeneity models. Moreover, we engineered an EGFRwt-targeting (D2C7) CARE-BEAR to exemplify the potential utility of CARE-BEAR beyond glioblastoma.
DDDR-45. INVESTIGATING TEMOZOLOMIDE RESISTANCE IN GLIOBLASTOMA USING A CLINICALLY RELEVANT DOSING REGIMEN
Authors: Harshita Kumar, Andrew Dhawan
Journal: Neuro-Oncology (2024)

Abstract The standard of care of management for glioblastoma, the most common primary malignant brain tumor in adults, involves maximal safe surgical resection followed by adjuvant chemoradiotherapy and six cycles of adjuvant temozolomide (TMZ). Approximately half of all treated patients develop chemoresistance to TMZ. The evolution of chemoresistance to temozolomide in vitro has historically involved continuous exposure to drug, as opposed to clinical dosing schedules, which involve five days of treatment followed by 23 days of recovery. Thus, in this study, we examined the emergence of chemoresistance to TMZ in vitro, using a clinical dosing regimen. Temozolomide dose response to RN1, an MGMT promoter unmethylated, IDH-wildtype, patient-derived glioblastoma cell line, was determined using cell titer glo. Cells were treated with TMZ for five days, followed by 23 days of recovery, in cycles. In each subsequent cycle, the dose of TMZ used was adjusted to previous cycle’s IC50, the concentration at which 50% of cell growth is inhibited. This protocol was repeated over three rounds. Cells treated with TMZ, as compared to the DMSO-treated control population, gradually acquired chemoresistance with a continuous increase in IC50. Our protocol therefore highlights how a clinically relevant dosing regimen may help capture the trajectory by which chemoresistance emerges, also allowing for the exploration of the molecular mechanisms underlying this phenomenon.
EXTH-37. ALLOSTERIC MITOCHONDRIAL CLPP AGONIST ONC206 ALTERS STRESS RESPONSE, METABOLIC AND EPIGENETIC PROFILES TO ELICIT ANTI-CANCER EFFICACY IN HIGH-GRADE GLIOMAS
Authors: Varun V Prabhu, Cristina Maranto, Andrew Lee, Scott Foster, Joshua E Allen
Journal: Neuro-Oncology (2024)

Abstract Dordaviprone (ONC201) is a dopamine receptor D2/3 (DRD2/3) antagonist and allosteric ClpP agonist that has demonstrated durable responses in recurrent H3 K27M-mutant glioma patients. ONC206, a derivative of ONC201 with nanomolar potency that also targets DRD2/3 and ClpP, is in Phase I trials for central nervous system tumors. We characterized target relevance, human ClpP binding, in vitro efficacy, downstream signaling and response determinants associated with ONC206 in high-grade gliomas (HGG). Co-crystallization with ClpP that assembles as a tetradecameric complex revealed an allosteric ligand interaction with distinctions in the ONC206-ClpP overall conformation relative to the ONC201-bound or apo complex, including an increase in the resolved pore size and decreased complex height. ONC206 was more potent than ONC201 in cell-free human ClpP casein/peptide degradation assays). Accordingly, HGG cell lines and patient-derived cells exhibited increased sensitivity to ONC206 relative to ONC201 and generally required a shorter duration of exposure. Unlike DRD2, CRISPR-mediated ClpP knockout in HGG cell lines blunted ONC206 sensitivity. Metabolomics revealed elevated α-ketoglutaric acid, α-hydroxyglutaric acid, and glutaric acid. Proteomics indicated inhibition of multiple mitochondrial pathways including OXPHOS and TCA cycle. TCA cycle enzyme α-ketoglutarate dehydrogenase (KGDH) was inhibited in a ClpP-dependent manner. Western blotting showed downregulated ClpX, and upregulated ATF4/CHOP, H3 K27me3 and H3 K36me3. Next-generation sequencing of acquired resistance cell lines, which exhibited cross-resistance to ONC201 and ONC206, revealed diverse ClpP missense mutations distributed across various monomer interfaces. Both intrinsic and well as ONC206-stimulated ClpP proteolysis were mitigated by these mutations, which was congruent with an absence of the tetradecameric assembly. These ClpP mutations recapitulated resistance and, conversely, wildtype ClpP overexpression restored sensitivity. Thus, allosteric ClpP agonism is a key determinant of ONC206 activity in HGG by altering stress response, metabolic, and epigenetic profiles.
TMIC-82. CHARACTERIZATION OF GENETIC MARKERS AND BIOLOGICAL PROCESSES UNDERLYING THE TRANSITION OF GLIOBLASTOMA CELLS FROM A DIFFERENTIATED TO A STEM-CELL-LIKE STATE
Authors: Mahlet Mekonnen, Anubhav Chandla, Meera Suresh, Brian Aguirre, Shir Gur, Madhuri Wadehra, Isaac Yang
Journal: Neuro-Oncology (2024)

Abstract BACKGROUND The main drivers of Glioblastoma (GBM) tumor growth are elevated angiogenesis and heightened characteristics of stemness. These driving factors make GBM an extremely invasive and aggressive tumor. While the GBM tumor microenvironment can be classified into several molecular subtypes, one common characteristic is the atypical induction of various signal transduction pathways including the receptor tyrosine kinases (RTKs), pro-angiogenic, and stem-cell-determining transcription factors, which all play important roles in GBM tumor formation, growth, and progression. OBJECTIVE To investigate the regulations of RTKs, pro-angiogenic, and stem-cell–determining transcription factors in two different tumor environments - monolayer cultures that induce a more differentiated state and neurosphere cultures that select for stem-like cells. METHODS Neurosphere- and monolayer-forming cell samples were cultured from four primary GBM cell lines including HK-336, HK-374, U87, and GS-154. RNA sequencing was performed at the Technology Center for Genomics and Bioinformatics at the University of California, Los Angeles. The transcriptomic data findings were validated by qPCR and western blot assays. RESULTS Our transcriptomic data revealed the significant upregulation of EGFR, PDGFR-α, VEGFA, and SOX2 in the neurosphere-forming HK-336, HK-374, U87, and GS-154 primary GBM cells. Consistent with the transcriptomic data, western blot, and qPCR assays demonstrated significantly higher expressions of these genes in the neurosphere-forming compared to the monolayer-forming GBM cells. Neurosphere-forming GBM cells possess stem-cell-like characteristics with the ability to self-renew and differentiate via the induction of various genes and disease progression pathways. CONCLUSIONS Neurosphere-forming GBM cells demonstrate upregulation of SOX2, EGFR, PDGFR-α, and VEGFA in RNA sequencing, western blot, and qPCR assays. Multipotent drug therapies designed to target multiple gene regulation pathways involving RTKs, pro-angiogenic, and stem-cell-determining transcription factors may be necessary to effectively treat GBM. Understanding the underlying mechanisms driving these aberrant cellular pathways could provide valuable insights for developing targeted therapies against this aggressive brain cancer.
DDDR-46. TARGETING TRANSGLUTAMINASE 2 (TGM2) ENHANCES SENSITIVITY OF GLIOBLASTOMA CELL LINES TO RADIOTHERAPY AND TEMOZOLOMIDE
Authors: Katherine Lan, Fatemeh Jamali, Vincent April, Siham Sabri, Bassam Abdulkarim
Journal: Neuro-Oncology (2024)

Abstract Glioblastoma (GBM), the most aggressive and common primary brain tumor in adults, remains highly resistant to conventional therapeutics, including radiation therapy (RT), largely due to its molecular heterogeneity. Few biomarkers have been identified that successfully guide or predict treatment response. Transglutaminase 2 (TGM2), a ubiquitous multifunctional enzyme involved in numerous signal transduction pathways related to tumorigenesis, has recently been suggested to drive chemoradioresistance. Here, we investigate the effects of disrupting TGM2 by pharmacologic inhibition or CRISPR knockout (TGM2-KO) on GBM cell’s response to RT and Temozolomide (TMZ) chemotherapy. Using western blotting and clonogenic assays, we show that the allosteric TGM2 inhibitor, GK921, stabilizes p53 expression and impedes reproductive ability at IC50 and IC25 concentrations. TGM2-KO and GK921 (at IC10 and lower) sensitized GBM cell lines to RT with almost equivalent efficacy, resulting in a 2- to 3-fold suppression of clonal expansion compared to scramble controls or irradiation alone. We also demonstrate increased sensitivity of GBM cell lines to TMZ upon inhibition of TGM2 by GK921. Our findings indicate that the use of TGM2 inhibitors, such as GK921, could enhance the efficacy of RT and the potency of TMZ, positioning TGM2 as a promising therapeutic target that may improve standard treatment of GBM cells expressing TGM2.
TMIC-79. IDH1-R132H REWIRES AUTOPHAGY IN THE GLIOMA MICROENVIRONMENT TO FACILITATE TUMOR PROGRESSION AND RESPONSE TO RADIATION
Authors: Kaushik Banerjee, Felipe Nunez, Anzar Mujeeb, Ava Mausar, Claire Tronrud, Ziwen Zhu, Ayman Taher, Padma Kadiyala, Stephen Carney, Maria Belen Garcia-Fabiani, Andrea Comba, Mahmoud Alghamri, Brandon McClellan, Syed Faisal, Zeribe Nwosu, Hanna Hong, Tingting Qin, Maureen Sartor, Mats Ljungman, Shi-Yuan Cheng, Henry Appleman, Pedro Lowenstein, Joerg Lahann, Costas Lyssiotis, Maria Castro
Journal: Neuro-Oncology (2024)

Abstract Gliomas are primary brain tumors with a poor prognosis. IDH1R132H exhibits a gain of function mutation leading to 2-hydroxyglutarate (2HG) production. We previously demonstrated, 2-HG mediated epigenetic rewiring is associated with better prognosis and its presence impacts several cellular functions including immune responses and enhanced DNA-damage response in IDH1R132H gliomas harboring p53 and ATRX loss-of-function mutations. Also, IDH1R132H elicits metabolic reprogramming which implies that IDH1R132H could modify the energetic state of gliomas with consequences in tumor biology and therapeutic responses. In this study, RNA-seq and ChIP-seq data revealed human and mouse IDH1R132H gliomas have downmodulated gene ontologies related to mitochondrial metabolism. This was paralleled by a decrease in glycolysis, rendering autophagy as a source of energy for IDH1R132H glioma cells. We also found that IDH1R132H-neurospheres have decreased levels of oxygen consumption and extracellular acidification rates, characteristic of an autophagic/quiescent state when compared to IDH1WT-neurospheres. Analysis of the autophagy pathway revealed that both human and mouse IDH1R132H gliomas have increased expression of pULK1-S555, pATG4b-S383, enhanced conversion of LC3I to LC3II, and decreased expression of pULK1-S757, p62 indicating that IDH1R132H cells have augmented autophagy activity compared to IDH1WT cells. Blocking autophagy selectively impairs the growth of IDH1R132H glioma cells in vitro. Targeting autophagy by systemic administration of synthetic protein nanoparticles packaged with siRNA targeting Atg7 sensitized IDH1R132H glioma cells to radiation-induced cell death, resulting in tumor regression, long-term survival, and immunological memory when used in combination with irradiation. Our results thus indicate that the metabolic changes in IDH1R132H glioma cells lead to compromised mitochondrial functions and increased autophagic activity which contributes to their radioresistance, representing a novel therapeutic target for IDH1R132H cells. *Corresponding author: Maria G. Castro: mariacas@med.umich.edu Equal contributions: KB-FN-AM-AM-CT Funding: This work was supported by National Institutes of Health/National Institute of Neurological Disorders &amp; Stroke (NIH/NINDS) Grants: [R37-NS094804, R01-NS122165, R21-NS123879-01 awarded to MGC]; [R01-NS122378, R01-NS122234 awarded to PRL], Ian’s Friends &amp; Chad Tough Foundation.
EXTH-20. EXPLORING EUPHOL’S THERAPEUTIC EFFECT IN ADULT AND PEDIATRIC BRAZILIAN HIGH-GRADE GLIOMAS PRE-CLINICAL MODELS
Authors: Mirella Baroni, Leticia Tshikawa, Raquel Megid, Flavia Scremim, Izabela Gomes, Gustavo Teixeira, Luiz Fernando Lopes, Bruna Mançano, Allan Polverini, Ismael Lombardi, Carlos Junior, Silvia Teixeira, Rui Reis
Journal: Neuro-Oncology (2024)

Abstract High grade gliomas (HGG) are among the most aggressive brain tumors affecting both adults and children. Adult HGG (aHGG) account for almost 25% of all brain tumors in adults, with glioblastoma (GBM) being the predominant subtype. Pediatric HGG (pHGG), though less common, accounts for 3-15% of primary brain tumors in children and exhibits distinct genetic profiles compared to aHGG. Standard treatment for HGG in both adults and pediatric patients includes maximal surgical resection followed by temozolomide (TMZ)-based chemotherapy and radiation therapy. Our group previously reported that euphol, a natural compound derived from the sap of Euphorbiaceae family plants, exerts cytotoxicity effects on glioma cells. In this study, we investigated the therapeutic potential of euphol in primary cell cultures and xenograft models derived from six Brazilian HGG patients, including three adults and three pediatrics. In vitro, euphol exposure significantly reduced cell viability reduction, clonogenic capacity, and migration, while enhancing apoptosis in all six primary cultures. Additionally, euphol sensitized glioma cells to TMZ, resulting in a synergistic cytotoxic effect. In vivo, euphol reduced tumor growth in both GBM and pHGG models, and prolonged the survival of mice in the GBM orthotopic experiment. These findings highlight the promising therapeutic potential of euphol for treating high-grade gliomas in both adult and pediatric populations.
EOLP-02. END-OF-LIFE CHALLENGES IN NEURO-ONCOLOGICAL PATIENT CARE: A YOUNGNOA SURVEY
Authors: Lazaros Lazaridis, Niklas Pepper, Sarina Agkatsev, Raphael Bodensohn, Rebecca Berg, Corinna Seliger, Peter Hau, Michael Platten, Stephanie Combs, Iris Mildenberger, Michael Müther, Sied Kebir
Journal: Neuro-Oncology (2024)

Abstract BACKGROUND Malignant brain tumors inevitably relapse, almost always causing significant functional and neurological impairments. Thus, palliative care is crucial in managing individuals with malignant brain tumors. It is essential for neuro-oncologists to be well-prepared to openly communicate about and meet the palliative needs of these patients. With this survey, we sought to evaluate palliative care practices in Germany and their impact on the treatment of neuro-oncological patients. METHODS We conducted an anonymous, interdisciplinary survey targeting palliative care practices among neuro-oncologists in Germany, all members of the Neuro-oncology Working Group of the German Cancer Society. The questionnaire, designed in close coordination with board-certified palliative care specialists, was distributed to 450 physicians. It collected personal information and assessed respondents’ knowledge of and access to palliative care structures. The survey was conducted online from March 31 to April 30, 2023. RESULTS Ninety-two physicians completed the survey. Of these, 81 (88%) reported feeling comfortable with end-of-life conversations, while 11 (12%) did not. No significant differences were observed between the two subgroups regarding their level of medical education (p=0.7140), workplace (p=0.4966), sex (p=0.9999), medical specialty (p=0.5478), or region of practice (p=0.9999). However, those comfortable with end-of-life discussions had significantly more palliative care training either during specialty training (p=0.0475) or through active participation in palliative care courses (p=0.0254). Further detailed analysis is in progress. CONCLUSIONS The survey indicates that while the majority of participants are comfortable with end-of-life discussions, a clear correlation exists between their comfort level and the extent of palliative care training received. This highlights the critical need for enhanced and targeted palliative care education within neuro-oncology training programs to prepare physicians for the complex communication and care challenges in neuro-oncological palliation. Further analysis will continue to explore additional educational and systemic factors that could increase the quality of palliative care in neuro-oncology.
TMIC-76. PRMT5 MODULATES T CELL PROLIFERATION IN GLIOBLASTOMA TUMOR MICROENVIRONMENT
Authors: Erin Walker, Aimee Dowling, Miyeon Jung, Celine Ertekin, Desmond Brown, Yeshavanth Banasavadi-Siddegowda
Journal: Neuro-Oncology (2024)

Abstract INTRODUCTION Glioblastoma, the most common malignant brain tumor, presents a significant obstacle because of its immunosuppressive tumor microenvironment, complicating standard treatment approaches. Protein Arginine Methyltransferase 5 (PRMT5) that regulates cellular functions by symmetrically dimethylating arginine residues is dysregulated in glioblastoma. Inhibiting PRMT5 induces apoptosis and senescence in the differentiated and undifferentiated glioblastoma tumor cells respectively. As PRMT5 is known to play an important role in immune cell response and T cell reprogramming, in this study we sought to probe the role of PRMT5 in the modulation of glioblastoma tumor immune response. METHODS We inhibited PRMT5 using small molecule inhibitor (LLY283) or PRMT5 target specific siRNA in patient-derived primary GBM neurospheres (GBMNS) and assessed the T-cell proliferation and MDSC induction by flow cytometry. Further, we also probed for PDL-1 and IL-6 expression by ELISA and westernblot assays. RESULT: PRMT5 inhibition significantly increased CD4+ T-cell proliferation but the MDSC induction was suppressed. As PDL-1/IL-6 axis is known to play a significant role in both anti-tumorigenic T-cell proliferation and pro-tumorigenic MDSC induction, we probed for the expression of PDL-1 and IL-6. While PRMT5 blockade reduced PDL-1 expression, IL-6 expression was upregulated. CONCLUSION Our results suggests that PRMT5 inhibition increases T-cell proliferation potentially by blocking MDSC induction. Further studies are underway to understand the nexus between PDL-1/IL-6 and modulation of MDSC/T-cell activation in the context of PRMT5 status in glioblastoma and their potential impact on the anti-tumorigenic effect in an in vivo GBM model.