tbuckley/cabot-search huggingface dataset:
BIOM-37. EXPLORING L-TYPE AMINO ACID TRANSPORTER 1 (LAT1) AS A DIAGNOSTIC MARKER AND THERAPEUTIC TARGET IN MALIGNANT PERIPHERAL NERVE SHEATH TUMORS (MPNST)
Authors: Guangfeng Wang, Dana Borcherding, Xiaochun Zhang, Kevin He, Nikki Fettig, Kooresh Shoghi, Angela Hirbe
Journal: Neuro-Oncology (2024)

Abstract OBJECTIVES Malignant peripheral nerve sheath tumors (MPNST) are aggressive soft tissue sarcomas that frequently arise from benign plexiform neurofibromas (PN). Approximately half of MPNST are associated with Neurofibromatosis type 1 (NF1). Despite partial elucidation of the molecular mechanisms underlying MPNST, diagnosis remains challenging, and prognosis is poor. Previously, we found that MPNST cells have elevated βIII-spectrin, a cytoskeletal protein involved in cell morphology and regulation of transporters, including L-type Amino Acid Transporter 1 (LAT1). LAT1 facilitates transport of large neutral amino acids and is upregulated in other cancer types. Our objective is to investigate LAT1 as a diagnostic marker and therapeutic target for MPNST. METHODS Gene and protein expression were determined by qPCR and WES protein analysis, respectively. The effect of shRNA knockdown of LAT1 in MPNST cells was assessed using IncuCyte proliferation assays as well as multiple mouse models. Tumor uptake of [18F] FDOPA, primarily transported by LAT1, in MPNST PDX tumors was assessed using PET/CT imaging. RESULTS LAT1 was expressed in MPNST (n=14) vs. benign PN tissues (n=6). Additionally, in human and murine MPNST cells, shRNA-mediated knockdown of LAT1 suppressed proliferation of MPNST cells in vitro and tumor growth in vivo. In a subcutaneous tumor growth model, intratumor injection of shLAT1 lentivirus reduced tumor volume to approximately 50% of control. Furthermore, uptake of [18F] FDOPA by LAT1 in MPNST PDX tumors was detected by PET/CT imaging. WU-356 PDX tissues exhibited higher LAT1 expression as well as increased uptake of [18F] FDOPA in tumors. Conversely, PET imaging showed significantly lower uptake of [18F] FDOPA in LAT1 knockdown tumors (p&amp;lt;0.05). CONCLUSIONS These results suggest that LAT1 promotes the growth and survival of MPNST cells. In addition, these findings demonstrate the potential use of LAT1 and the radiotracer [18F] FDOPA as a diagnostic biomarker in the management of MPNST.
EXTH-34. ACETYLATION SUPPRESSION MEETS ONCOLYTIC VIRUSES FOR THE TREATMENT OF PEDIATRIC DIFFUSE MIDLINE GLIOMA
Authors: Akhila Parthasarathy, Marc Garcia Moure, Jiasen He, Andrew Gillard, Alyssa Paparella, Dong Ho Shin, Andres Lopez-Rivas, Hong Jiang, Xuejun Fan, Lethan Hampton, Timothy Phoenix, Frederick Lang, Nicolas Young, Marta Alonso, Candelaria Gomez-Manzano, Juan Fueyo
Journal: Neuro-Oncology (2024)

Abstract Diffuse midline glioma (DMG) remains a devastating pediatric brain tumor without effective treatment. In a recent clinical trial, we demonstrated the feasibility and efficacy of Delta-24-RGD oncolytic virus combined with radiation therapy in patients with newly diagnosed diffuse intrinsic pontine gliomas (NCT03178032). Because the adenoviral protein E1A binds to P300 and redirects acetylation upon virus infection, we hypothesized that combining oncolytic adenoviruses with P300 inhibitors will cause a remarkable shifting in acetylation and the post-translational landscape of DMG, ultimately enhancing the anti-glioma effect of oncolytic viruses. Western blot analyses showed a longitudinal reduction in H3K27ac (89%) and H3K18ac (99%) in a panel of human (TP54 and SF8628) and murine (24B_1 and 26C_7) DMG cells after Delta-24-RGD infection. In addition, using histone fractionation by high-performance liquid chromatography, we detected an increase in total H3 upon adenovirus infection. Mass spectrometry of histones in the human DIPG cell line, TP54 using middle-down approach illustrated post-translational changes across histones, including hypoacetylation of the H3.2K14 mark. To further modify histone acetylation in DMG during Delta-24-RGD infection, we combined virotherapy with C646, a selective and competitive histone acetyltransferase inhibitor of the E1A-binding p300/CBP complex of proteins. In vitro, the combination of Delta-24-RGD with C646 synergistically increased cell death in a panel of human and murine DIPG cell lines (zip-scores ranging from 6.3-11.3 with zip-scores above 10 being indicative of synergy). Ongoing experiments using a panel of adenoviruses expressing E1A with defective P300 binding or expressing a dominant-negative form of P300 or wild-type P300 are designed to test the extent to which E1A binding of P300 drives hypoacetylation in DMG upon virus infection. In addition, we are performing in vivo experiments to establish the anti-cancer effect of the combination of Delta-24-RGD and P300 inhibitors in clinically relevant animal models of DMG, with a feasible translation to the clinic.
EXTH-35. REPURPOSING OF CLINICALLY APPROVED GLUTAMATE ANTAGONISTS TO TREAT GLIOBLASTOMA
Authors: Julia Uriach Dasca, Samuel Marashli, Eric C Holland, Michael Weller, Hans-Georg Wirsching
Journal: Neuro-Oncology (2024)

Abstract The neurotransmitter glutamate plays a fundamental role in promoting epilepsy and tumor progression in glioblastoma. Glioblastoma cells secrete glutamate into the tumor microenvironment via the cystine-glutamate antiporter system Xc, leading to neuronal hyperexcitability, excitotoxicity, and tumor cell invasion. Additionally, glutamatergic neuroglioma synapses drive glioma progression in preclinical tumor models. To pharmacologically counteract effects of glutamate in glioblastoma, we employed a triple combination of anti-glutamatergic drugs: gabapentin, sulfasalazine, and memantine, which target glutamate synthesis, release, and post-synaptic signaling, respectively. In genetically engineered murine glioblastoma models, daily treatment with this triple combination prolonged median survival. This survival benefit was not observed with single or double drug combinations, nor with the standard antiepileptic drug levetiracetam, indicating the potential synergy and efficacy of this drug combination beyond merely treating epilepsy. Importantly, these preliminary results support the rationale for the ongoing phase Ib/II randomized clinical trial GLUGLIO, which explores the efficacy of combined gabapentin, sulfasalazine, and memantine in conjunction with standard chemoradiotherapy in patients with newly diagnosed glioblastoma (NCT05664464).
EPID-02. BLOOD-BASED CLASSIFICATION OF IDH-STATUS OF NON-ENHANCING GLIOMAS: A MACHINE LEARNING APPROACH
Authors: Sara Hadad, Gayathri Warrier, Lucie Mccoy, Helen Hansen, Jiaying Chen, Terri Rice, Margaret Wrensch, Jennie Taylor, Jennifer Clarke, John Wiencke, Annette Molinaro
Journal: Neuro-Oncology (2024)

Abstract BACKGROUND Non-invasive determination of IDH mutational status in patients with glioma could offer significant therapeutic opportunities. While IDH wildtype (WT) tumors typically show enhancement on MRI, IDH mutant (MUT) tumors often lack this enhancement. However, relying solely on anatomic radiology may lead to misclassification, and currently, tissue acquisition is the primary method for assessing IDH-status in gliomas. These limitations hamper the development of neoadjuvant or intraoperative therapeutic strategies based on IDH-status; thus, more minimally invasive methods to determine IDH-status are needed. In this study, we assessed peripheral immune cell proportions, which vary by glioma subtype, from pre-surgery peripheral blood samples as an alternative method of classifying the IDH-status in gliomas without enhancement. MATERIALS AND METHODS We employed a highly accurate large language model (GPT-4-Turbo-128k) with over 99% accuracy to read radiology notes and exclude patients with enhancing gliomas. Then, we identified 12 immune cell subtypes from whole blood using deconvolution algorithms based on DNA methylation data. These immune cell subtypes, along with patient age, were integrated into a machine learning model (random forest) to predict IDH-status (WT vs. MUT), leveraging conditional Generative Adversarial Networks to generate synthetic data and mitigate bias in the datasets. Two independent datasets were included for training and validating the model. RESULTS The random forest model had an AUC of 0.90 and accurately identified IDH-status in 81% of a training set of 287 gliomas (65 WT and 222 MUT at varied time points after diagnosis). In an independent validation data set of 99 gliomas (6 WT and 93 MUT) from pre-surgery blood samples, the AUC was 0.93, and accurately predicted IDH-status in 92% of cases with a sensitivity of 93% and specificity of 83%. CONCLUSIONS We predicted the IDH-status of non-enhancing gliomas using patients’ age and immunomethylomic data from pre-surgical peripheral blood samples. This minimally invasive approach is a promising step toward reducing risk and enabling earlier therapies based on IDH-status.
EXTH-21. WINNING THE TUG OF WAR BETWEEN VIRUS AND TUMOR IMMUNODOMINANCE IN GLIOMAS TREATED WITH ONCOLYTIC ADENOVIRUSES USING TOLEROGENIC STRATEGIES
Authors: Dong Ho Shin, Bulent Ozpolat, Andrew Gillard, Marc Garcia-Moure, Hong Jiang, Andres Lopez-Rivas, Akhila Parthasarathy, Xuejun Fan, Ramon Alemany, Marta Alonso, Jiasen He, Chibawanye Ene, Gheath Al-Atrash, Frederick Lang, Candelaria Gomez-Manzano, Juan Fueyo
Journal: Neuro-Oncology (2024)

Abstract Phase 1 and 2 clinical trials of our oncolytic adenovirus Delta-24-RGD for patients with recurrent malignant gliomas have demonstrated its safety and efficacy, and showed that 20% of the patients experienced long-term tumor remissions often associated with inflammatory responses and tumor infiltration of lymphocytes. Based on our preliminary data, we expected that the most frequent tumor-infiltrating CD8+ T cell clones will target adenoviral hexon, with a single virus-specific clone representing up to 5% of the total population. Competition between T cells for resources may limit the expansion of subdominant clones recognizing tumor antigens. We hypothesized that mitigating virus-specific immunity allows the expansion of tumor-specific T cells and results in better therapeutic efficacy. In mice, intravenously injected nanoparticles encapsulating adenoviral antigens preferentially accumulated in the liver (P&amp;lt;0.0001), where self-reactive immune cells are deleted through peripheral tolerance. RNA-sequencing of antigen-specific T cells isolated after nanoparticle injection revealed enriched expression of gene sets involved in immune tolerance through clonal deletion and T cell anergy, including increased expression of immune checkpoint molecules (P&amp;lt;0.001). In glioma-bearing mice treated with virotherapy in combination with nanoparticle administration, tumor infiltrating lymphocytes exhibited decreased IFNγ secretion against viral antigens and increased secretion against tumor antigens, suggesting a redirection of the immunity from anti-viral to anti-tumoral (P&amp;lt;0.05). Importantly, virotherapy with nanoparticles increased the overall survival of tumor-bearing mice compared to virus treatment alone (P&amp;lt;0.001). To further characterize the roles of virus- and tumor-specific immune cells during virotherapy we are analyzing the T cell receptor repertoire of surgical specimens from nine glioma patients treated with Delta-24-RGD in a phase 1 clinical trial. In summary, our data provide the basis for a future clinical trial using tolerogenic strategies to redirect immunodominance of the viral to the glioma antigens, and represent a novel strategy to enhance anti-tumor immunity during virotherapy of brain tumors.
TMIC-72. MECHANISMS TO ENHANCE IMMUNOTHERAPY EFFICACY IN A RAT MODEL OF MEDULLOBLASTOMA
Authors: Cooper Stateler, Samantha Holland, Jared Stoller, Doonyaporn Wongsawaeng, Leslie Muldoon, Edward Neuwelt, Prakash Ambady, Ramon Barajas
Journal: Neuro-Oncology (2024)

Abstract Medulloblastoma is the most common malignant brain tumor in children. Current treatments are limited by irreversible CNS damage, particularly in high-risk subgroups. Innate immune cells constitute a significant portion of the brain tumor microenvironment, nurturing tumor growth and suppressing key defense mechanisms. Leveraging the innate immune system for improved clinical outcomes remains unrealized. We aimed to determine if Baicalein (Bac), a known tumoricidal M1 macrophage potentiator, improves efficacy in medulloblastoma models. Nude rats (N=10) were implanted with MB002 medulloblastoma intracerebellar patient-derived non-WNT/non-SHH, group 3 xenografts. Baseline T2 and gadolinium-enhanced MRI (Gd-MRI) T1 estimated pre-therapy tumor volumes. Single fraction 2Gy irradiation to the tumor-bearing hemisphere with 20mg/kg temozolomide (CRT) combined with Bac 100mg/kg PO QD daily x8 (N= 3) was administered. CRT alone (N= 3) and no treatment (N= 4) served as controls. Seven days post-therapy, Gd-MRI and histology established tumor volume and CD68 and CD163 expression (T-test; p≤ 0.05). MRI demonstrated the therapeutic effect of Bac+CRT compared to CRT only (P&amp;lt; 0.01) and untreated controls (P= 0.01). This was confirmed via histology volumes; untreated group (P&amp;lt; 0.01) and a trend toward significance vs. CRT only (P= 0.22). The normal brain demonstrated a near significant increase in CD68 expression in the Bac+CRT compared to CRT and control (P&amp;lt; 0.06). A near statistically significant decrease in CD163 expression was observed at the tumor margin for Bac+CRT compared to CRT only (P&amp;lt; 0.06). Likewise when comparing CRT to untreated control (P&amp;lt; 0.05). Preliminary data suggests Bac+CRT uniquely induces an innate immune response within the brain that expresses features of M1 polarization, resulting in effective tumoricidal efficacy in preclinical medulloblastoma models. Current studies are evaluating the mechanisms of efficacious innate immune targeted therapies in larger sample sizes with the eventual goal of clinical translation.
NIMG-32. ORAL ADMINISTRATION OF DEUTERATED CHOLINE AS A NEW APPROACH TO PROVIDE HIGH TUMOR-TO-BRAIN IMAGE CONTRAST IN DEUTERIUM METABOLIC IMAGING (DMI)
Authors: Victor Osoliniec, Monique Thomas, Robin de Graaf, Henk De Feyter
Journal: Neuro-Oncology (2024)

Abstract BACKGROUND Metabolic imaging using FDG-PET is a key component of disease management in many cancers outside of the brain, but in brain tumors it often shows low tumor-to-brain contrast because of high background signal from normal brain. We explore generating cancer-specific metabolic image contrast using Deuterium Metabolic Imaging (DMI), which is a novel 2H magnetic resonance spectroscopic imaging-based technique. DMI was applied after oral administration of deuterated choline, an essential nutrient needed for membrane synthesis whose uptake is often increased in tumors. METHODS Total choline (tCho) DMI was performed in an orthotopic model of glioblastoma, F344 rats (n=11) implanted with RG2 cells, on an 11.7 tesla MRI scanner, with isotropic spatial resolution of 2.5 mm. tCho-DMI data were collected for 36 min during intravenous infusion (IV, n=6) or after 3 days of oral administration (PO, n=5) of [2H9]-choline chloride dissolved in sterile water. At a dose of 285 mg/kg body weight, bolus-continuous IV infusion via the tail vein required 1.57 ml for a 250-gram rat. PO administration via gavage on 3 consecutive days used the max daily dose recommended for human adults, 50 mg/kg. Results - In the PO group, average tumor tCho concentration was 0.78±0.14 mM and 0.20±0.05 mM in contralateral normal brain. In the IV group, the tCho concentration was 0.88±0.18 mM in the tumor, and 0.18±0.03 mM in normal brain (PO vs. IV: p=0.52). Tumor-to-brain contrast was 5.9±1.2 in PO-administered animals, and 7.1±3.3 for animals receiving IV 2H-choline, (p=0.54). CONCLUSIONS - In a preclinical GBM model oral administration of [2H9]-choline resulted in comparably high tumor-to-brain image contrast on tCho-DMI-based maps as during IV infusion. Work is ongoing to identify the different choline metabolites that contribute to the tCho signal. Because oral administration of choline is very safe, this approach could facilitate the translation of tCho-DMI to human subjects.
EPCO-16. METHOD TO MODEL AND CORRECT NOISE IN SINGLE-NUCLEI RNA-SEQUENCING DATA FROM POST-MORTEM BRAIN
Authors: Jacqueline J Peng, Donald M O’Rourke, MacLean P Nasrallah, Zev A Binder, Dana Silverbush
Journal: Neuro-Oncology (2024)

Abstract Post-mortem brain samples are crucial for neuropathological research. For brain cancers, they provide insights about disease progression, microenvironmental factors, and treatment resistance. In some brain diseases, brain tissue may only be available post-mortem. Establishing a reference atlas of healthy brain also requires post-mortem donations. Beyond logistical and ethical challenges of post-mortem samples, there are also post-mortem factors that mask biological signal. In this study, we specifically aim to model post-mortem gene expression changes in single-nuclei RNA-sequencing (snRNA-seq) data. We analyze a public snRNA-seq dataset of pediatric high-grade glioma (pHGG) that has matched samples at initial resection and autopsy. We find a clear gene signature, composed of mitochondrial genes, stress-related genes, and metabolism-related genes, that is upregulated post-mortem. This signature also appears in post-mortem snRNA-seq data from other brain diseases and healthy donors. We classify it as “post-mortem noise”. We model the post-mortem noise as a combination of technical and biological artifact. The technical artifact is correlated with the percentage of mitochondrial reads and is a general measure of sample quality. The biological artifact is correlated with post-mortem interval and represents gene expression changes due to post-mortem stress. We apply our model to the pHGG data by regressing out the technical and biological artifact. Removing the post-mortem noise results in an improvement in malignant versus normal cell prediction, cell type classification, and the uncovering of pathways related to glioma progression. We confidently identify several normal cell types and predict their interactions with cancer cells, highlighting the utility of wider possible margins post-mortem. Therefore, after removing post-mortem noise, we analyze glioma progression at an unparalleled timepoint and characterize late-stage changes in the tumor microenvironment. In conclusion, we develop a method that models post-mortem noise in snRNA-seq brain data. Our method can be broadly applied to future brain cancer studies using post-mortem tissue.
EXTH-40. IMMUNOPHENOTYPING OF RWTC-MBTA AUTOLOGOUS CANCER VACCINE IN PRECLINICAL GLIOBLASTOMA MODELS
Authors: Herui Wang, Juan Ye, Rogelio Medina, Yaping Zhang, Samik Chakraborty, Ondrej Uher, Katerina Hadrava Vanova, Jan Zenka, Karel Pacak, Zhengping Zhuang
Journal: Neuro-Oncology (2024)

Abstract Despite advances in immunotherapy, glioblastoma multiforme (GBM) remains challenging to treat due to its low inherent immunogenicity and a suppressive tumor microenvironment. Converting “cold” GBMs to “hot” tumors is crucial for effective immune activation and improved patient outcomes. We comprehensively characterized the rWTC-MBTA autologous cancer vaccine, consisting of Mannan-BAM-anchored irradiated whole tumor cells, Toll-like receptor ligands (LTA, Poly(I:C), R-848), and an anti-CD40 agonistic antibody, in preclinical GL261 and SB28 GBM models. A substantial number of vaccinated mice exhibited complete regression of GBM tumors in a T-cell-dependent manner, with no significant toxicity. Long-term tumor-specific immune memory was confirmed upon tumor rechallenge. In the vaccine-draining lymph nodes of the SB28 model, rWTC-MBTA vaccination triggered a major rise in cDC1 12 hours post-treatment, followed by an increase in cDC2, moDC, and pDC on Days 5 and 13. Enhanced cytotoxicity of CD4+ and CD8+ T cells in vaccinated mice was verified in co-culture with tumor cells. Comprehensive immunophenotyping in the GL261 and SB28 GBM microenvironments confirmed decreased regulatory T cells and increased CD4+ and CD8+ T cell infiltration in vaccinated mice. T-cell exhaustion analyses revealed an increase in the Tim3+CD8+ T cells. No significant differences were observed in the quantification of M-MDSC and PMN-MDSC between control and vaccinated mice, but PD-L1 expression significantly increased in M2 macrophages in vaccinated mice. Our findings demonstrate that rWTC-MBTA induces potent and long-term adaptive immune responses against GBM, warranting further investigation of combinations with other immunotherapies for enhanced efficacy.
EXTH-36. SHIFTING FROM EPIGENETICS TO THE EPICHAPEROME: HSP90 AS A THERAPEUTIC TARGET FOR H3K27M DIFFUSE MIDLINE GLIOMA (DMG)
Authors: Stefanie-Grace Sbergio, Sanja Pajovic, Arun Anguraj Vadivel, Jun Watanabe, Javal Sheth, Laura Canty, Gabriela Chiosis, Mark Nitz, Rintaro Hashizume, Cynthia Hawkins
Journal: Neuro-Oncology (2024)

Abstract Diffuse midline gliomas (DMG) are lethal pediatric brain tumours, the majority of which have truncal histone (H3K27M) mutations. To investigate cellular vulnerabilities of histone mutant cells we generated oligodendrocyte precursor cells (OPC) isogenic cell lines and performed a high-throughput synthetic lethality drug screen (2400 small molecules). This identified HSP90 inhibitors as a potential therapeutic option for H3K27M DMG. We hypothesize that epichaperome HSP90 inhibitors present a new therapeutic approach targeting multiple aspects of DMG oncogenicity. HSP90 inhibitors, PU-H71 and PU-HZ151, effectively reduced viability of DMG lines in vitro in the low nanomolar range and result in caspase mediated cell death (p&amp;lt;0.0001 1 uM, p&amp;lt;0.05 500 nM, n=6). PU-HZ151 treated mice had a survival benefit vs control mice injected with orthotopic DMG xenografts (p=0.0012). In diseased cells, activated HSP90 forms a scaffold defined as the epichaperome. To unravel the molecular mechanisms of epichaperome inhibition in DMG cells, we performed epichaperomics – a pull down of epichaperome HSP90 with co-chaperones and clients followed by LC-MS/MS analysis. We identified an interactome enriched with proteins involved in cell cycling, RAS/MAPK signaling, immune response, and metabolic reprogramming. Proteomic and phosphoproteomic profiling of DMG cells post-PU-HZ151 treatment provided insights into the direct downstream effects critical for maintaining DMG viability, identified functional vulnerabilities primed by epichaperome inhibition including downregulation of cell cycling, and upregulation of HSF1 mediated cellular response to stress. In silico screening and kinase enrichment analysis highlighted CSNK2A1 as a top active kinase in DMG cells following PU-HZ151 treatment. To enhance the therapeutic efficacy of epichaperome inhibition, we employed the CSNK2A1 kinase inhibitor, CX-4945, in combination with PU-HZ151, resulting in the effective ablation of DMG patient cells in vitro. These data highlight the potential of epichaperome inhibitors for DMG treatment, as they target multiple DMG oncogenic pathways.