bluuebunny/crossref_metadata_2025_split huggingface dataset:
EXTH-41. THE microRNA miR-138 MAY BE RESPONSIBLE FOR SOME OF THE EFFECTS OF METABOLIC KETOSIS ON MALIGNANT GLIOMA
Authors: Perryman Richard , Zeng Qingyu , Raha Oishik , O’Neill Kevin , Scheck Adrienne , Syed Nelofer 
Published: December 2020

Abstract
We and others have demonstrated that altering metabolism through the use of a ketogenic diet (KD) has numerous effects in mouse models of malignant glioma including slowed growth, reduced hypoxia and angiogenesis, enhanced survival and potentiation of the effects of radiation and chemotherapy. These effects are recapitulated in vitro when the ketone β-hydroxybutyrate (BHB) is added to mouse and human malignant glioma cells grown under high glucose conditions. BHB has been demonstrated to be an epigenetic modifier, providing a potential mechanism for the pluripotent effects of ketones even in the presence of high glucose. Therefore, we have analyzed alterations in microRNA (miRNA) expression in tumors and cells treated with a KD or BHB, respectively. MicroRNAs are short, single-stranded, noncoding RNAs that posttranscriptionally control gene expression. Each miRNA can affect the expression of many genes and they are implicated in all hallmarks of cancer. We found a number of miRNAs deregulated in tumor tissue from mice fed a KD, particularly mmu-miR-138 which was increased over 30-fold relative to tumors from mice fed a standard diet. MiR-138 is involved in a variety of anti-tumor effects that correlate with our data from KD treated gliomas. We have shown that ketones radiosensitize glioma cells, potentially through a reduction in DNA damage repair. MiR-138 has been shown to reduce the expression of H2AX which plays a key role in sensing and repairing DNA damage. Hypoxia inducible factor-1α (HIF-1α) is also a target of miR-138, and we have demonstrated a reduction in hypoxia, angiogenesis and the expression of HIF-1α in tumors from mice fed a KD. Furthermore, when we genetically engineered tumor cells to express miR-138 and injected them into mice, only necrotic tumor foci were found. Thus, we suggest that miR-138 is an important regulatory mechanism for the anti-tumor actions of metabolic ketosis in glioma.
EXTH-47. PRECISION IMMUNOTHERAPY VACCINES FOR GLIOBLASTOMA USING CANCER IMMUNOGENOMICS AND SELECTIVE GENE ENRICHMENT STRATEGY
Authors: Trivedi Vrunda , Yang Changlin , Yegorov Oleg , Dyson Kyle , Mitchell Duane 
Published: December 2020

Abstract

BACKGROUND
Development of successful immunotherapy targeting antigens in Glioblastoma (GBM) remains a challenge owing to the heterogeneous nature of GBM and the low mutation burden. It is therefore important to identify multiple tumor antigens that can be targeted simultaneously. Our goal is to develop a personalized RNA vaccination approach that employs the use of cancer immunogenomics in identifying tumor immunogenic epitopes and target enrichment strategies that allow for targeting only the tumor specific antigens.

APPROACH
RNAseq and WES was performed for murine GBM tumors KR158 and GL261. Using our Open Reading Frame Antigen Network (O.R.A.N.) algorithm, we identified neoantigens and tumor-associated antigens (TAAs) which includes cancer testis and developmental antigens that are aberrantly over-expressed in the KR158 and GL261 tumors. The genes identified as harboring the target epitopes were subjected to a gene enrichment strategy which included hybridization, capture and amplification of our identified genes from a pool of total tumor cDNA. The precision RNA libraries generated from the enriched cDNA samples were then validated for enrichment of target genes using RNAseq.

RESULTS
We predicted 12 neoantigens and 15 TAAs as immunogenic targets for the KR158 tumor and 192 neoantigens and 37 TAAs for GL261. Pre-capture and amplification, the 27 KR158 tumor genes constituted only 1.14% of the total tumor cDNA pool, however, we were able to enrich the selected genes to up to 95% of the cDNA pool. The IVT RNA library generated from the enriched cDNA templates also consisted of a 90–95% majority of the predicted tumor-specific genes and only 5–10% of the genes were background.

CONCLUSION
We have demonstrated the ability to generate tumor antigen specific personalized RNA libraries for murine GBM tumors. RNA vaccines targeting specifically and simultaneously numerous tumor antigens, will pave way for the future of immunotherapy vaccines without the induction of intolerable autoimmunity.
EXTH-50. ACTIVATION OF THE MITOCHONDRIAL CLPP PROTEASE IS SYNTHETICALLY LETHAL WITH HDAC1/2 INHIBITION IN GLIOBLASTOMA MODEL SYSTEMS
Authors: Schiffgens Salveena , Nguyen Trang , Shu Chang , Elena Bianchetti , Torrini Consuelo , Karpel-Massler Georg , Siegelin Markus 
Published: December 2020

Abstract
Novel therapeutic targets are critical to unravel for recalcitrant malignancies, such as the most common primary brain tumor in adults, glioblastoma (GBM). Heterogeneity remains a hallmark of primary glial brain tumors and therefore targeting several pathways simultaneously is an appropriate approach. Here, we showed that pharmacological activation of the mitochondrial ClpP protease through utilization of the novel imipridone compounds (ONC206 and ONC212) in combination with global (Panobinostat) and selective (romidepsin) HDAC – inhibitors caused synergistic reduction of viability in established and patient-derived xenograft (PDX) cultures of human GBM. This effect occurred independent of TP53 status and was partially mediated by activation of a cell death with apoptotic features accompanied by activation of initiator and effector caspases as well as cleavage of PARP. Consistently, the combination treatment altered the expression of anti-apoptotic and pro-apoptotic Bcl-2 family members, resulting in down-regulation of Bcl-xL and Mcl-1. Knockdown experiments targeting Noxa, BIM, Bcl-xL and Mcl-1 confirmed a functional implication of these proteins in the reduction of cellular viability mediated by the combination treatment. Importantly, knockdown of the ClpP protease significantly rescued the reduction of cellular viability by ClpP activators and the combination treatment, respectively, suggesting critical involvement of this protein. Finally, using a PDX model, we demonstrated that the combination treatment of romidepsin and ONC206 reduced tumor growth more potently than single treatments or vehicle by enhanced reduction of cellular proliferation and pronounced induction of cell death in vivo. Collectively, these observations suggest that the efficacy of HDAC-inhibitors might be significantly enhanced through ClpP activators in model systems of human GBM.
EXTH-52. GLIOBLASTOMA-TARGETING AUTOLOGOUS INDUCED NEURAL STEM CELL THERAPY: EVALUATING SAFETY, TOXICITY, PERSISTENCE, AND TRANSPLANT METHODS IN A POST-SURGICAL CANINE MODEL
Authors: Bomba Hunter , Sheets Kevin , Valdivia Alain , Khagi Simon , Ruterbories Laura , Mariani Christopher , Borst Luke , Tokarz Debra , Hingtgen Shawn 
Published: December 2020

Abstract

BACKGROUND
Glioblastoma patient survival statistics have remained unchanged for more than three decades. Despite tumor resection and chemoradiotherapy, recurrence is inevitable. Moreover, the invasive behavior of glioblastoma confounds treatment. To improve patient survival statistics, a targeted therapy that can home to distant tumor foci is desperately needed. Induced neural stem cells (iNSCs) armed with cytotoxic payloads have proven efficacious against human xenograft models of glioblastoma. To further propel iNSCs to human clinical trials, we investigated the safety, toxicity, and persistence of iNSCs in a canine model.

METHODS
Autologous iNSCs generated from the skin of four non-tumor-bearing, purpose-bred, male beagles were engineered to express TRAIL and thymidine kinase (TK). iNSCs were loaded with ferumoxytol to facilitate MRI-tracking. Canines were divided into two cohorts to denote iNSC administration route: scaffold encapsulation or intracerebroventricular (ICV). Two dose levels were investigated: 1′106 iNSCs/kg or 3′106 iNSCs/kg. The scaffold cohort received a single dose of iNSCs while the ICV cohort received three doses of iNSCs via a Rickham reservoir. To activate TK, canines were administered valganciclovir. Canine health was assessed via neurological exams, MRI, and serial blood, urine, and CSF analyses.

RESULTS
No acute injection reactions were observed. Three of four canines exhibited surgery-induced blindness. Urine and CSF analyses were unremarkable. Unexpectedly, blood analyses showed transient neutropenia. Hypodense signal was observed on all MRI sequences through endpoint. Post-mortem histopathology of the spleen, liver, and lung were unremarkable. As expected, brain tissues exhibited gliosis, fibrous thickening, and inflammation. Spinal cords exhibited acute hemorrhaging, attributed to perimortem CSF draws. Surprisingly, significant testicular degeneration was observed; this was confirmed to be caused by valganciclovir. In conclusion, iNSCs exhibit limited toxicity and warrant further exploration.

FUTURE DIRECTIONS
Prospective studies will investigate the efficacy of autologous iNSCs in a spontaneous canine glioma model in preparation for human clinical trials.
EXTH-53. A BRAIN-PENETRANT MICROTUBULE-TARGETING AGENT THAT DISRUPTS HALLMARKS OF GLIOMA TUMORIGENESIS
Authors: Horne Eric , Vicente Ruiz Juan J , Cimino Patrick , Jung Erik , Xu Cong , Diaz Philippe , Hamel Ernest , Kumasaka Debra K , Wagenbach Michael J , Winkler Frank , Wordeman Linda G , Holland Eric , Stella Nephi 
Published: December 2020

Abstract
Most cancer therapeutics developed to date are excluded from the brain and are therefore ineffective in treating glioma, the most devastating type of brain cancer in adults. Microtubule targeting agents (MTAs) are indispensable medicines to treat a wide range of solid and hematopoietic tumors, and evidence suggests that glioma is sensitive to MTAs; but most MTAs do not cross the blood-brain-barrier. To address this limitation, we developed a brain-penetrant MTA, ST-401, that inhibited the growth of human glioma in culture at nanomolar concentrations. ST-401 bound to the colchicine site, inhibited tubulin assembly and reversibly reduced microtubule (MT) dynamics. Testing of ST-401 on the NCI 60 cancer cell panel indicated that its anti-tumor activity does not correlate with any of the compounds tested thus far through this platform but showed weak correlations for two MTA that work through distinct mechanisms: taxol (p=0.46) and vinblastine (p=0.34). Thus, ST-401 may kill cancer cells through a novel mechanism related to disruption of MT function. We discovered that ST-401 killed patient-derived (PD) glioma isolates in both mitosis and interphase, and inhibited the formation of tumor microtubes, MT-rich structures that connects glioma cells to a network that is resistant to standard therapies. Pharmacokinetic analysis of ST-401 in mice shows brain penetration reaching antitumor concentrations, and in vivo testing of ST-401 in a xenograft model demonstrated significant antitumor activity. In an immunocompetent mouse model of platelet-derived growth factor B-driven glioma, ST-401 significantly enhanced the therapeutic efficacies of standard care therapies temozolomide and radiation therapy. Our study identified novel aspects of glioma tumorigenesis that exhibit enhanced sensitivity to MTAs and shows that the brain-penetrant MTA, ST-401, represents a promising chemical scaffold to develop therapeutics for the treatment of patients diagnosed with glioma.
EXTH-62. PRECLINICAL EFFICACY OF THE IMIPRIDONE ONC-206 AGAINST MEDULLOBLASTOMA
Authors: MacDonald Tobey , Malhotra Anshu , Liu Jingbo , Zhang Hongying , Schneiderjan Matthew , Vega Jose Velazquez , Prabhu Varun , Allen Joshua 
Published: December 2020

Abstract
Treatment for medulloblastoma (MB) is typically ineffective for MYC amplified or metastatic SHH, Group 3 and 4 subgroups. Promising preclinical and clinical results have been obtained for adult and pediatric malignant glioma treated with ONC-201, a selective antagonist of DRD2, a G-protein coupled receptor that regulates prosurvival pathways. Herein, we report the activity of ONC-201 and ONC-206, which has increased non-competitive antagonism of DRD2, against MB. We treated three different MB cell types representative of SHH- and Group 3-like cells, with varied levels of DRD2 expression, and consistently observed increased cell death in a dose-dependent manner at lower doses of ONC-206 compared to ONC-201. We also evaluated ClpP as an additional drug target in MB. ClpP is a mitochondrial protease that has been shown to directly bind and be activated by ONC 201, and is highly expressed at the protein level across pediatric MB, malignant glioma and ATRT, but not normal brain. We observed that similar to ONC-201, ONC-206 treatment of MB cells induces the restoration of mitochondrial membrane potential to the non-proliferative state, degradation of the mitochondrial substrate SDHB, reduction in survivin and elevation in ATF4 (integrated stress response). Importantly, ONC-206 treatment induced significant cell death of patient-derived SHH, WNT, and Group 3 tumors ex vivo and Group 4 cells in vitro, while having no observable toxicity in normal brain. ONC-206 treatment of a transgenic mouse model of Shh MB in vivo significantly reduces tumor growth and doubles survival time in a dose-dependent manner following 2 weeks of therapy. Additional in vivo data will be reported in preparation for a planned Phase I study of ONC-206 in children with malignant brain tumors.
EXTH-67. PHARMACOLOGIC INHIBITION OF LYSINE SPECIFIC DEMETHYLASE-1 (LSD1) AS AN ADJUVANT IMMUNE-SENSITIZATION STRATEGY IN DIFFUSE INTRINSIC PONTINE GLIOMA (DIPG)
Authors: Bailey Cavan , Collier Tiara , Henry Verlene , Monje Michelle , Nazarian Javad , Lee Dean , Wang Linghua , Gopalakrishnan Vidya , Becher Oren , Chandra Joya 
Published: December 2020

Abstract
Diffuse midline gliomas (DMG), including brainstem DIPG (diffuse intrinsic pontine glioma), are incurable pediatric brain tumors. Mutations in the H3 histone tail (H3.1/3.3-K27M) are a feature of DIPG, highlighting epigenetic aberrations in these tumors. Lysine specific demethylase-1 (LSD1), is an enzyme that acts upon mono and di-methylated histone H3K4/K9, and pharmacological inhibitors of its enzymatic and scaffolding domains are clinically viable. Patient-derived DIPG cell lines, orthotopic mouse models, and pediatric high-grade glioma (pHGG) datasets were used to evaluate effects of LSD1 inhibitors on cytotoxicity and immune gene expression. Because an unique immune signature was sen with enzymatic LSD1 inhibitors in DIPG cells in vitro, immune cell cytotoxicity was assessed in DIPG cells pre-treated with LSD1 inhibitors and informatics platforms were used to determine immune infiltration of pHGG. Selective cytotoxicity and an immunogenic gene expression signature was established in DIPG cell lines and in brainstem tumor-bearing mice using clinically-relevant LSD1 inhibitors. Pediatric HGG patient sequencing data demonstrated survival benefit using this LSD1-dependent gene expression signature. On-target binding of catalytic LSD1 inhibitors was confirmed in DIPG and pre-treatment of DIPG with these inhibitors increased lysis by natural killer (NK) cells. CIBERSORT analysis of patient data confirmed NK infiltration is beneficial to patient survival while CD8 T-cells are negatively prognostic. Catalytic LSD1 inhibitors are non-perturbing to NK cells while scaffolding LSD1 inhibitors are toxic to NK cells and do not induce the gene expression signature in DIPG cells. Treatment of orthotopic xenograft bearing DIPG mouse models with catalytic LSD1 inhibitors and NK cells showed a significant reduction in tumor burden. In summary, we find that LSD1 inhibition using catalytic inhibitors is both selectively cytotoxic and promotes a functional immune gene expression signature that is associated with NK cell killing, representing a therapeutic opportunity for pHGG.
EXTH-70. CYP450 AND METABOLIC PROFILING OF ANTI-CANCER IMIPRIDONE ONC201
Authors: Morrow Sara , Prabhu Varun , Tarapore Rohinton S , Guo Ailan , Fang Yunlan , Nej Magdalena , Stogniew Martin , Allen Joshua 
Published: December 2020

Abstract
Imipridone ONC201 is an investigational agent in phase II clinical trials for high grade gliomas as a single agent once weekly. Systemic and tumor exposure to ONC201 exceeds therapeutic thresholds consistently; however, exposure is variable despite fasted conditions and does not strongly covary with body weight or body surface area. Clinical trials with ONC201 have restricted the use of concomitant medication that induce or inhibit cytochrome P450 (CYP) enzymes; however, several supportive medications for glioma patients such as corticosteroids and anti-seizure medications can affect these enzymes. Studies in pooled human liver microsomes revealed that ONC201 is not an inducer of seven major drug-metabolizing human CYP enzymes: CYP 1A2, 2B6, 2C8, 2C9, 2C19, 2D6, and 3A4. However, ONC201 inhibits multiple CYPs IC50 values ranging from 34.9 to 428.6 μM and is substrate of CYP3A4 and, to lesser extent, other CYPs. Given potential metabolism of ONC201 by these enzymes, we conducted metabolic profiling in human hepatocytes that revealed at least 13 metabolites; however, only one was &gt;10% abundance. The major metabolite, termed ONC207, that lacks a benzyl moiety of ONC201 was assayed by LC-MS-MS in plasma samples obtained from 16 ONC201-treated H3 K27M-mutant glioma patients. Peak plasma concentrations of ONC207 relative to ONC201 was 22% (range: 6%-48%) and its abundance was not correlated with ONC201, suggesting that variable exposure to ONC201 may not be associated with variable metabolism. ONC207 does not inhibit dopamine receptor D2 or cancer cell viability in contrast to the parent compound. In summary, ONC201 is an inhibitor and substrate, but not an inducer, of multiple CYP enzymes. The major metabolite of ONC207 appears to be biologically inactive and is unlikely to explain variable ONC201 exposure or its prolonged biological activity that outlives its systemic presence.
EXTH-72. CONTINUOUS INFUSION STUDIES REVEAL THE POTENCY OF ELACRIDAR TO ACT AS A PHARMACO-ENHANCER FOR TREATMENT OF INTRACRANIAL DISEASES BY INHIBITING ABCB1 AND ABCG2 AT THE BLOOD-BRAIN BARRIER
Authors: van Tellingen Olaf , de Gooijer Mark C , Zuidema Stefanie , Meurs Amber , Çitirikkaya Ceren H , Venekamp Nikkie , Beijnen Jos H 
Published: December 2020

Abstract
The blood-brain barrier (BBB) is a formidable hurdle to successful pharmacotherapy of intracranial diseases. ABCB1 and ABCG2 are efflux transporters that play an important role in the BBB, keeping substances out of the brain. Elacridar and tariquidar are third-generation ABCB1-inhibitors developed for treatment of multidrug-resistant tumors. Later, they were shown to also inhibit ABCG2. We aim to improve pharmacotherapy of brain cancer by concomitant use of potentially effective drugs with elacridar. This study was undertaken to determine the relationship between the plasma concentration of the inhibitor and the brain-to-plasma (B/P) ratio of (model) substrate drugs in order to assess which type of drug may best qualify taking into account clinically achievable plasma levels of the inhibitor. We used Abcg2;Abcb1a/b double knockout (DKO), Abcb1a/b KO, Abcg2 KO and wild-type mice receiving a cocktail of 9 drugs at a fixed low dose plus a range of doses of inhibitor by 3-h intraperitoneal infusion to achieve steady-state conditions. DKO mice are the reference for complete inhibition, while single KO mice allow interrogation of the other transporter when using dual substrate drugs. Complete inhibition of Abcb1 by elacridar requires plasma levels of about 1000 nM. Inhibition of Abcg2 is more difficult. For erlotinib and palbociclib about 1000 nM of elacridar is sufficient, but other more profound substrate drugs (e.g. vemurafenib and afatinib) do not reach the B/P ratios achieved in DKO mice, even at 4000 nM. The improvement in B/P ratio that can be reached differs per substrate. Compounds like palbociclib benefit markedly from elacridar with B/P ratios rising from 0.25 to 7, whereas others (e.g. erlotinib and dasatinib) increase from about 0.10 to only 0.40. Thus, elacridar is an efficient pharmaco-enhancer of ABCB1 substrates and weaker ABCG2 substrates, but is not able to improve brain delivery of drugs that are profound ABCG2 substrates.
EXTH-73. HETEROGENEITY IN CELL SURFACE ANTIGEN AND HLA CLASS I EXPRESSION IN PEDIATRIC BRAIN TUMORS AND ITS IMPACT ON T-CELL IMMUNOTHERAPY
Authors: Houke Haley , Zhu Xiaoyan , Mercer Kimberly S , Stripay Jennifer L , Chiang Jason , Baker Suzanne , Roussel Martine F , Gottschalk Stephen , Krenciute Giedre 
Published: December 2020

Abstract
Immunotherapy with tumor antigen-specific chimeric antigen receptor (CAR) and/or ab (T-cell receptor) TCR T-cells has the potential to improve clinical outcomes of patients with pediatric brain tumors. As a prerequisite for successful T-cell therapies, we must determine which cell surface antigens are expressed and targetable in these tumors, and if HLA Class I is present, which is necessary for ab TCR T-cell recognition. Therefore, in this study we systematically analyzed pediatric patient-derived orthotopic xenograft (PDOX) brain tumor samples for cell surface expression of five known CAR targets: IL13Ra2, HER2, EphA2, B7-H3, and GD2, as well as HLA Class I. We established and validated a flow cytometry-based method of profiling tumor-associated antigens. Fifty-three PDOX samples have been profiled to date, including medulloblastoma, high grade glioma (HGG), diffuse intrinsic pontine glioma (DIPG), atypical teratoid rhabdoid tumor (ATRT), and ependymoma, among others. Our results showed high variability within and between individual samples. B7-H3 was the most consistently expressed, seen in 98% of the samples tested. We validated these results by conventional immunohistochemistry staining for B7-H3 and found comparable RESULTS: HLA Class I was highly expressed on all HGG samples but was undetectable on 47.8% of other brain tumor samples. This suggests that down-regulation of HLA class I is one mechanism by which brain tumors evade conventional T-cells, and that HLA-independent CAR T-cells would be useful therapies. We also compared expression of antigens in fresh patient samples and corresponding PDOX tumors and saw that they were indeed similar. To our knowledge, this is the largest group of pediatric brain tumor PDOX samples methodically analyzed for potential CAR target antigens and HLA Class I. Taken together, our data demonstrate that elimination of tumors by CAR T-cell immunotherapies will require targeting multiple antigens, and our profiling method could inform how to circumvent antigen-negative relapse.