tbuckley/cabot-search huggingface dataset:
DDDR-47. TARGETING HTR2B SUPPRESSES NON-FUNCTIONING PITUITARY ADENOMA GROWTH AND SENSITIZES CABERGOLINE TREATMENT VIAINHIBITING GΑQ/PLC/PKCΓ/STAT3 AXIS
Authors: Shaojianlin Lin, Liangbo Wang, Changxi Han, Yuting Dai, Li Xue, Zhe Bao Wu
Journal: Neuro-Oncology (2024)

Abstract BACKGROUND Managing non-functioning pituitary adenomas (NFPAs) is difficult due to limited drug treatments. Cabergoline’s (CAB) effectiveness for NFPAs is debated. This study explores the role of HTR2B in NFPAs and its therapeutic potential. METHODS We conducted screening of bulk RNA-sequencing data to analyze HTR2B expression levels in NFPA samples. In vitro and in vivo experiments were performed to evaluate the effects of HTR2B modulation on tumor growth and cell cycle regulation. Mechanistic insights into the HTR2B-mediated signaling pathway were elucidated using pharmacological inhibitors and molecular interaction assays. RESULTS Elevated HTR2B expression was detected in NFPA samples, which was associated with increased tumor survival. Inhibition of HTR2B activity resulted in the suppression of tumor growth through modulation of the G2M cell cycle. The inhibition of HTR2B with PRX-08066 was found to block STAT3 phosphorylation and nuclear translocation by interfering with the Gαq/PLC/PKC pathway. A direct interaction between PKC-γ and STAT3 was critical for STAT3 activation. CAB was shown to activate pSTAT3 via HTR2B, reducing its therapeutic potential. However, the combination of an HTR2B antagonist with CAB significantly inhibited tumor cell proliferation in HTR2B-expressing pituitary tumor cell lines, a xenografted pituitary tumor model, and patient-derived samples. Analysis of patient-derived data indicated that a distinct molecular pattern characterized by upregulated HTR2B/PKC-γ and downregulated BTG2/GADD45A may benefit from combination treatment with CAB and PRX-08066.
TMIC-80. HIGH-DIMENSIONAL HISTOPATHOLOGIC EVALUATION OF THE HYPOXIC TUMOR MICROENVIRONMENT IN GLIOBLASTOMA
Authors: Shreya Gandhi, Olivia Singh, Sheila Mansouri, Shirin Karimi, Phoebe Lombard, Anna Dvorkin-Gheva, Carlos Velasquez, Hafsah Ali, Kaviya Devaraja, Qingxia Wei, Ronald Wu, Mira Li, May Cheung, Mathew Voisin, Andrew Gao, David Hedley, Kenneth Aldape, Bradley Wouters, Gelareh Zadeh
Journal: Neuro-Oncology (2024)

Abstract Gliobastoma (GBM) is a highly aggressive solid tumor of the brain, characterized by a hypoxic tumor microevironment (TME) leading to histopathological features of necrosis, microvascular proliferation and deregulated hypervascularization. The heterogeneous nature of GBM results in a gradient of intra-tumoral hypoxia that causes molecular changes to specific cell populations within the bulk of the tumor. Our study is the first clinical study to utilize the exogenous oxygen-independent marker pimonidazole (PIMO) to identify the hypoxic TME using high-dimensional spatial and single-cell proteomics of specific cell populations within GBM. A cohort of 35 patients with primary GBM, recurrent GBM or IDH-mutant glioma were administered PIMO prior to surgical resection of tumor tissue for downstream bulk proteomic analysis of bulk tissue by serial immunohistochemistry and imaging mass cytometry (IMC) and single-cell analysis of dissociated tissue by Cytometry by time-of-flight (CyTOF). We utilized high-resolution imaging analyses to validate PIMO as a sensitive and stable marker for hypoxia against a panel of transiently expressed HIF-target genes and examine the inter- and intra-tumoral heterogeneity of hypoxia within each tumor subtype. A custom CyTOF marker panel was developed for further single-cell analyses of T-cell subsets and their functional states, myeloid cell subpopulations, natural killer cells, glial cells, and tumor cells in the hypoxic TME. We demonstrate the utility of PIMO to effectively study the hypoxic TME through spatial and single cell methods and further elucidate mechanisms of hypoxia-driven treatment resistance.
TMIC-77. ELUCIDATING THE ROLE OF PTPRZ1 SIGNALING IN DRIVING GLIOBLASTOMA PROGRESSION USING THE NOVEL HUMAN ORGANOID TUMOR TRANSPLANTATION SYSTEM
Authors: Ryan Kan, Weihong Ge, Can Yilgor, Elisa Fazzari, Patricia Nano, Daria Azizad, Matthew Li, Joyce Ito, Christopher Tse, Hong Tum, Jessica Scholes, Kunal Patel, David Nathanson, Aparna Bhaduri
Journal: Neuro-Oncology (2024)

Abstract Glioblastoma (GBM), the most malignant and aggressive primary brain tumor, is driven by both intrinsic genetic mutations and extrinsic factors from the tumor microenvironment (TME). GBM manipulates the TME to enhance its survival and proliferation through mechanisms such as forming functional synapses with adjacent normal cells and secreting immunosuppressive factors. Our laboratory has developed a novel human organoid tumor transplantation (HOTT) model, which allows for the interrogation of tumor-normal cell crosstalk at a molecular level and facilitates the dissection of specific signaling pathways that drive tumor progression and maintenance. Using single-cell transcriptomics on human GBM HOTTs, we identified the PTN-PTPRZ1 ligand-receptor interaction as a critical mediator of tumor-microenvironment communication. PTPRZ1, a receptor tyrosine phosphatase, has been previously implicated in glioma cell migration, and our data further elucidate its role in modulating tumor behavior. Specifically, we demonstrated that knockdown of PTPRZ1 within the TME of human cortical organoids significantly enhances glioma cell migration and inhibits differentiation, underscoring the essential role of PTPRZ1 in maintaining the tumor’s invasive phenotype. Further pharmacological inhibition of PTPRZ1’s catalytic activity with a small molecule revealed that these effects on cell fate determination are independent of its phosphatase activity. This suggests that PTPRZ1 exerts critical non-catalytic functions that are pivotal for GBM progression. To further investigate these non-catalytic mechanisms, we propose utilizing single-cell transcriptomics coupled with proximity labeling and proteomics. This approach will allow us to comprehensively map PTPRZ1-mediated signaling networks and elucidate their impact on tumor biology, potentially unveiling novel therapeutic targets. Our findings revealed a novel axis of GBM biology mediated by PTPRZ1 and highlighted the importance of considering microenvironmental interactions in the development of effective therapeutics for GBM.
EXTH-29. EVALUATION OF THE ANTITUMOR EFFECT OF A CHEMOTHERAPY-LOADED DEVICE FOR THE TREATMENT OF PRIMARY BRAIN TUMORS
Authors: Laurence Déry, Gabriel Charest, Brigitte Guérin, Mohsen Akbari, David Fortin
Journal: Neuro-Oncology (2024)

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.
TMIC-84. MOLECULAR EVOLUTION OF THE TUMOR AND ITS MICROENVIRONMENT AT RECURRENCE
Authors: Elaheh Hashemi, Akshaya R.L, Anupam Kumar, Viva Voong, Lin Lin Wang, Aaron Diaz, Joanna Phillips
Journal: Neuro-Oncology (2024)

Abstract Changes in the glioma immune microenvironment at recurrence may contribute to disease progression and therapeutic resistance. In prior studies we demonstrated that the circumscribed glioma, pleomorphic xanthoastrocytoma (PXA), was relatively immune enriched including activated cytotoxic CD8+ T cells and Iba1+ microglia/macrophages. While PXA are often low-grade, a significant fraction can recur and progress to higher grade. To determine how the tumor and its immune microenvironment changes with recurrence, we examined a cohort of tumors from patients with multiple resections. Using single-nucleus RNA sequencing (snRNAseq) and spatial molecular imaging we investigate the temporal changes in the tumor and its microenvironment. To begin, we analyzed samples from three patients with paired initial and recurrent tumor. A total of 22,465 immune and non-immune cells were analyzed. Compared to the initial, the recurrent tumor tended to have decreased numbers of T cells and T cells had lower expression of CD2 and GZMA. Pathway analysis for DE genes in TAMs demonstrated enrichment of genes associated with NTRK signaling, while pathways related to aerobic respiration and mitochondrial translation were decreased suggesting a less inflammatory phenotype. Tumor cells at recurrence demonstrated decreased expression of CD274 (PD-L1) and of the chemokine CXCL14, previously identified as a factor driving an anti-tumor CD8+ T cell response. In a cohort of 5 patients with paired initial and recurrent tumors, we observed increased numbers of CD163+ TAMs. Together these data suggest changes in the tumor-associated immune response at recurrence that may be relevant to therapy. Using murine models for the disease we are investigating the factors that regulate these changes.
EXTH-22. TARGETING MITOCHONDRIAL PROTEASE IN DIFFUSE GLIOMAS
Authors: Olga Kim, Zach Sergi, Guangyang Yu, Qi Li, Peng Lu, Ru-Ching Hsia, Robert Robey, Raj Chari, Herui Wang, Bao Tran, Thorkell Andresson, Michael Gottesman, Zhenggang Liu, Lee Graves, Edwin Iwanowicz, Jing Wu
Journal: Neuro-Oncology (2024)

Abstract BACKGROUND Targeting mitochondrial function has emerged as a promising therapeutic strategy in cancer treatment. TR107 is characterized as a specific activator of caseinolytic protease proteolytic subunit (ClpP) in the mitochondria, potentially affecting oncogenic pathways. Here, we investigated the effects of TR107 on adult malignant gliomas, IDH-wildtype and IDH-mutant METHODS We utilized patient-derived glioma cells to determine the efficacy of TR107 with cell viability, proliferation, cell cycle, and apoptosis assays. Immunofluorescent staining and electron microscopy (EM) were employed to uncover organelle morphological changes upon treatment. Mitochondrial function and ATP production were assessed in live cells utilizing Seahorse analysis. Global proteomics and RNA sequencing were performed to identify treatment-induced dysregulated pathways in glioma cells RESULTS Both IDH-wildtype and IDH-mutant glioma cell lines were highly sensitive to TR107, showing at least 100 times lower IC50 compared to the related compound ONC201. Genetic knock out of ClpP revealed that the growth inhibitory effects of TR107 are ClpP-dependent. Interestingly, IDH-mutant cell lines showed a more profound disintegration of mitochondrial morphology and dysregulation of mitochondrial function evidenced by an enhanced suppression of oxidative phosphorylation, mitochondrial complexes expression, mtDNA copy number, complex I activity, and ATP production, compared to IDH-wildtype cells. Six days of treatment with TR107 led to a complete inhibition of cell growth and up to 97% of cell death in IDH-mutant cells, while 50% of IDH-wildtype cells remained viable. Western blot, EM, and RNAsequencing analyses uncovered autophagy as a potential pro-survival mechanism in IDH-wildtype cells. Importantly, multiple metabolic and DNA repair-related pathways were affected by the treatment, suggested by global proteomics and RNA sequencing. Finally, TR107 was not affected by ABC transporters, supporting its potential use in brain tumor patients CONCLUSION TR107 demonstrated potent cytotoxic effects in patient-derived glioma cells by disrupting mitochondrial structural and functional integrity. TR107 efficacy in vivo is under investigation.
IMMU-14. TRANS-SPECIES ANALYSIS OF REPLICATION-REPAIR DEFICIENT (RRD) MEDULLOBLASTOMA AND RESPONSE TO IMMUNE CHECKPOINT INHIBITION: AN IRRDC REPORT
Authors: Anirban Das, Nicholas Fernandez, Adrian Levine, Kyle Smith, Evan Wang, Melissa Galati, Zoya Aamir, Jill Chung, Logine Negm, Hope Friedman, Katharine O’Flaherty, Owen Crump, Quang Trinh, Nuno Nunes, Vanessa Bianchi, Lucie Stengs, Melissa Edwards, Lincoln Stein, Eric Bouffet, Michael Taylor, Paul Northcott, Vijay Ramaswamy, Cynthia Hawkins, Uri Tabori
Journal: Neuro-Oncology (2024)

Abstract BACKGROUND Replication-repair deficiency (RRD) stemming from mismatch repair and polymerase proofreading gene defects (MMRD/PPD) lead to hypermutant childhood cancers, most frequently brain tumors. While medulloblastoma is reported, the clinical, genomic and immune landscape remains unknown. METHODS We analysed the genome, methylome, transcriptome (bulk, single-nuclei) and immune-microenvironment of the largest cohort of RRD-medulloblastoma patients enrolled by the International RRD Consortium and correlated these to clinical outcomes. RRD mice-models were used to preclinically assess response to immunotherapy. Results: RESULTS RRD-medulloblastoma (n=43) were enriched for anaplasia (61%) and localised disease (77%). Methylation/nano-string-based subgrouping failed to classify 40%, while the remaining clustered with the SHH-subgroup. Copy-number changes were notably infrequent (&amp;lt;20%). All tumors harboured hypermutation and microsatellite instability in contrast to non-RRD controls (p&amp;lt;0.0001). Pathogenic variants were frequent in POLE/POLD1 (80%), TP53 (48%) and SHH-pathway genes (PTCH1, SUFU, SMO: 56%). Interestingly, some tumors additionally had glioma-driver alterations (ATRX, NF1: ~50%), similar to RRD cerebellar glioblastoma, but distinct from both non-RRD medulloblastoma (n=791) and hemispheric glioblastoma (n=733) controls. Moreover, although bulk-transcriptome matched non-RRD SHH medulloblastoma, single-nuclei analyses suggested an earlier cell-of-origin potentially explaining the heterogenous phenotypes resulting from the driver mutations. Uniquely, immune analyses (gene expression and immunohistochemistry) demonstrated high intra-tumoral CD8 T-cell infiltration. Three-year progression-free survival was 60%. Outcome was worse for RRD-medulloblastoma harbouring TP53-mutation (p=0.04) and failing subgroup-classification (p=0.004). Nestin/Cre MSH2-/- POLE;p.S459F mice developing medulloblastoma recapitulated human disease and demonstrated response to anti-PD1 monotherapy. Recurrent/progressive human tumors including those harbouring TP53-mutations exhibited radiological responses to anti-PD1 monotherapy, which was associated with prolonged ongoing survival in comparison to those not treated with checkpoint-inhibitors (p=0.02). CONCLUSIONS Hypermutant RRD-medulloblastoma reveal heterogenous phenotypes due to unique spectrum of driver mutations and an early cell of origin. Their immune-hot microenvironment allows successful salvage treatment with checkpoint-inhibitors for those failing chemo-radiation, including the high-risk SHH/TP53-mutant and unclassified subgroups.
EXTH-24. THERAPEUTIC TARGETING OF MISLOCALIZED NUCLEAR ENVELOPE PROTEINS IN<i>MYC</i>-DRIVEN GROUP 3 MEDULLOBLASTOMA
Authors: Yujin Suk, Jorge Ibañez-Vega, Iqra Chaudhry, Martin Rossotti, Minomi Subapanditha, Petar Miletic, Stefan Custers, Laura Escudero, Alberto Delaidelli, Takuma Nakashima, Yuxi Xiao, Jason Moffat, Hiromichi Suzuki, Poul Sorensen, Kevin Henry, Chitra Venugopal, Giedre Krenciute, Sheila Singh
Journal: Neuro-Oncology (2024)

Abstract Medulloblastoma (MB) is the most common, malignant pediatric brain tumour comprised of four distinct molecular subgroups (WNT, SHH, Group 3, and Group 4). A subset of Group 3 MB tumors harbors focal amplifications of the MYC oncogene (MYC-G3MB) and are particularly prone to tumour recurrence due to their highly proliferative nature linked to its embryonic stem cell-of-origin and programming. We discovered that LBR, an inner nuclear transmembrane protein, while present in all cells at the nuclear envelope (NE), is aberrantly presented to the cell surface in MYC-G3MBs. Transcriptomic profiling of publicly available datasets identified significant NE protein enrichment in MYC-G3MB compared to normal tissue and high expression during fetal development that dampens postnatally and in adult samples. Immunohistochemistry analysis of LBR on patient tumors was able to significantly prognosticate overall and progression free survival. Flow cytometry analysis identified LBR cell surface expression in MYC-G3MBs with low to no expression in human neural stem cells and other MB subgroups. High resolution microscopy of endogenously tagged LBR revealed cell surface presentation to be linked to ER-like vesicles that directly trafficked to the cell surface in MYC-G3MBs. Transcriptomic analysis of LBR cell surface positive and negative cells identified LBR to be linked to mitotic processes and mislocalization was significantly enriched following exposure to chemotherapy and radiation in vitro and in vivo. Therefore, we demonstrate that LBR is an ideal therapeutic target for patients facing treatment-refractory MB and have generated single domain antibodies (sdAb) to develop LBR-CAR T cells. Validation of LBR sdAbs demonstrate on-target binding and comparable affinity and avidity to commercial LBR antibodies. There is an undeniable paucity of targets for MB patients stemming from the lack of neoantigens and genomic aberrations in pediatric tumors. The preclinical development and validation of novel immunotherapeutic targets such as LBR provides alternative therapies for patients otherwise facing palliation.
EXTH-23. NEW DNA-CROSSLINKING CHEMOTHERAPY IS EFFECTIVE AGAINST POST-TEMOZOLOMIDE MISMATCH REPAIR-DEFICIENT PATIENT-DERIVED HYPERMUTANT GLIOMAS
Authors: Matthew McCord, Wenxia Wang, Shejuan An, Thomas Sears, Jann N Sarkaria, C David James, Bruce Ruggieri, Ranjit S Bindra, Craig Horbinski
Journal: Neuro-Oncology (2024)

Abstract The DNA mismatch repair (MMR) pathway triggers glioblastoma (GBM) apoptosis when base mismatches induced by the alkylating agent temozolomide (TMZ) cannot be repaired. GBMs often develop hypermutation and resistance to TMZ through acquired inactivation of DNA MMR enzymes (MSH2, MSH6, MLH1, PMS2). A newly developed therapeutic, KL-50, fluoro-ethylates DNA bases, leading to DNA inter-strand cross-links. This form of DNA damage triggers MMR-independent apoptosis. Thus, KL-50 can target MMR-deficient tumor cells. Previous work showed that KL-50 is effective against GBM cell lines that were rendered TMZ-resistant through shRNA knockdown of MMR genes (PMID 35901163). In those studies, KL-50 was most effective when used in combination with an MGMT enzyme inhibitor, or in MGMT-deficient cells. Here, we extend those findings with a preclinical trial of KL-50 in GBM patient-derived xenografts (PDX), including PDX models of post-TMZ GBM that acquired MMR mutations and hypermutation through serial TMZ exposure (PMID 31852831). Among TMZ-naïve PDX, KL-50 extended survival of engrafted mice by 24 days for GBM6 (partially MGMT-deficient), and by 38 days for GBM12 PDX (fully MGMT-deficient) compared to vehicle (p&amp;lt;0.0001, Log-Rank). Combining KL-50 with 4.0 Gy radiation further extended survival of GBM12 mice (9 days, p=0.02), but not GBM6 mice. With engraftments of GBM6R-m185, a post-TMZ, MMR-deficient derivative of GBM6, 14/14 (100%) of KL-50 treated mice are still alive 60 days post-engraftment compared to 0/13 (0%) of vehicle control mice (median survival 37 days, p&amp;lt;0.0001, experiment ongoing). Complementary in vitro studies showed that GBM6R-m185 cells are more sensitive to KL-50 than TMZ at matched concentrations of 50µM (p=0.001, one-way ANOVA) and 100µM (p=0.047). These data demonstrate the potential of KL-50 in treating post-TMZ MMR-deficient recurrent gliomas.
EXTH-25. OPTIMIZATION OF NEW CHEMOTHERAPEUTIC AGENTS BY INTRA-ARTERIAL INFUSION IN GLIOBLASTOMAS
Authors: Juliette Latulippe, Laurent-Olivier Roy, Gabriel Charest, Fernand Jr Gobeil, David Fortin
Journal: Neuro-Oncology (2024)

Abstract Being the most aggressive malignant primary brain tumor, glioblastoma (GBM) is a difficult disease to treat. The first line treatment is well established, but most patients will relapse before or during the treatments. The overall survival is only 14,6 months while the progression-free survival is 6,9 months. In Sherbrooke, Dr Fortin prioritize the intra-arterial (IA) administration of chemotherapeutic agents (CTA) as a second line treatment. Unfortunately, certain patients will not respond or will even develop chemoresistance to the agents. Therefore, there is a strong need for bringing more CTAs onto clinical care. The maximal tolerable dosage (MTD) of every agent was first determined. Every CTAs were then administered IA by retrograde infusion in the external carotid but also intravenously (IV) by the caudal vein. We used the Fischer-F98 glioma rat model in our studies. For the efficacy study, we implanted 10 000 F98 cells into their brain. After 10 days, they received the treatment associated to their group. The animals were followed every day and were euthanized when their condition was too deteriorated. The dosages found in the MTD study for topotecan and cytarabine was 4 mg/kg and 8,75 mg/kg respectively while paclitaxel was too toxic. As for the efficacy study, the IA group of topotecan showed a promising outcome with a higher survival rate (29 days) compared to the IV one (23,5 days). As for the cytarabine, the opposite was observed (IA: 22 days, IV: 26,5 days). While topotecan and cytarabine could be given intra-arterially, only topotecan showed conclusive results. More animals will be added to this group to confirm this outcome. Cytarabine is not a good option since the IV group survived a longer time than the IA group. As for the paclitaxel, the intra-tumoral infusion will be tested to see if we can get positive results.