bluuebunny/crossref_metadata_2025_split huggingface dataset:
DDIS-19. USING MATCHED PRIMARY AND RECURRENT PEDIATRIC BRAIN TUMOR ORTHOTOPIC MOUSE MODELS(PDOX) TO ILLUSTRATE THE GENETIC REVOLUTION AND TO INFORM NEW ANTI-RECURRENT PERSONALIZED THERAPIES
Authors: Du Yuchen , Kogiso Mari , Braun Frank , Qi Lin , zhang Huiyuan , Lindsay Holly B , zhao Sibo , Kool Marcel , Stephan Clifford , Li Xiaonan 
Published: November 2019

Abstract

BACKGROUND AND PURPOSE
Despite standard treatment largely benefits patients’ survival, tumors may recur as aggressive, therapy resistant relapses. It is imperative to obtain a better understanding of molecular changes that occur after primary tumor resection and treatment. We established a serial of PDOX models using patient tumor tissues procured at different time of patient clinical history.

METHODS
Dissociated tumor cells were cultured in vitro and transplanted into mouse brains. DNA and RNA were then extracted from tumor tissues or cells from patient and established xenografts. Whole genome methylation and transcriptomic profiling as well as histological phenotypes were examined. Standard therapies were conducted in xenografts.

RESULTS
Currently, three sets of matched primary and recurrent tumor xenografts (19850PNET, 100815GGG/GBM and 5958MB) were established. Tumor-take rate increased from 50–70% of primary tumors to 100% of recurrent tumors with decreased tumor onset time (6 months to 3 months), which demonstrated progressive phenotypes. RNA sequencing reveals preserved and newly changed genetic changes in recurrent tumors. High-throughput drug screening discovered a shared and a diverse panel of therapeutic targets that could be selected further for in vivo drug treatment especially for recurrent tumors. Tumor xenografts responded to standard therapy either same or different from clinic outcome, which might indicate the intrinsic or inducible evolutional molecular changes during cancer progression and treatment at different stages.

CONCLUSION
Three sets of matched primary and recurrent pediatric brain tumors, PNET/PNET, GGG/GBM and MB/MB, were successfully established in pediatric orthotopic mice tumor models (PDOXs) providing clinically-relevant and biologically-accurate animal model systems for development of novel therapeutic targets especially for recurrent tumors. Responses of primary and recurrent tumor xenografts to standard chemo-therapy were different possibly due to evolutionarily molecular changes in recurrent tumors during progression or induced by therapies.
DDIS-22. DRUG SCREEN IN PATIENT-DERIVED IDHMUT GLIOMA STEM CELLS IDENTIFIES SEVERAL FDA-APPROVED ANTINEOPLASTIC AGENTS
Authors: Dao Trong Philip , Pusch Stefan , Unterberg Andreas , Herold-Mende Christel , Warta Rolf 
Published: November 2019

Abstract

OBJECTIVE
The discovery of the Isocitrate Dehydrogenase (IDH) mutation in glioma has led to a paradigm shift on how we see glioma biology. While it is clear, that IDH mutated (IDHmut) and wildtype (IDHwt) tumors have to be viewed as separate entities, the underlying biological differences are still matter of extensive research. Difficulties in cultivating IDHmut glioma stem cells (GSC) have led to a paucity of preclinical models in IDHmut glioma making the discovery of new effective chemotherapeutic agents problematic. We therefore sought to perform a repurposing drug screen in five patient-derived IDHmut GSC lines to discover potential effective antineoplastic agents, already approved by the FDA.

METHODS
Patient tumor tissue was obtained in our neurosurgical department to isolate and establish IDHmut GSC lines. (D)-2-hydroxyglutarate (2HG) levels were measured in the cell culture supernatant of IDHmut GSCs using an enzymatic diaphorase/resazurin system. The drug library provided by the Developmental Therapeutics Program (DTP) of the National Cancer Institute (NCI) consisting of 146 FDA-approved drugs was used for the screen. Cell viability was assessed with the CellTiterGlo assay (Promega).

RESULTS
Despite several passages, the IDHmut GSCs showed stable production of 2HG and were therefore suitable for the drug screen. Cells were cultured as neurospheres and subjected to the test compounds for 72h in concentrations ranging from 0.1nM – 1µM. We identified several compounds in two IDHmut GSC lines (NCH551b, NCH1681) that had a half maximal inhibitory concentration (IC50) below 1µM and could confirm its cytotoxic potential in additional three IDHmut GSC lines (NCH612, NCH620, NCH3763).

CONCLUSION
In this study, we present a feasible preclinical model for a high-throughput drug screen in patient-derived IDHmut GSCs and identified several FDA-approved antineoplastic agents which warrant further investigations.
DDIS-23. CMV-BASED PLASMID DNA VACCINE FOR GBM USING THE UNITE PLATFORM
Authors: Adhikari Amit , Toll Barb , Johnson Yoshimi , Marketon Anthony , Wilson Greg , Macauley Juliete , Heiland Teri 
Published: November 2019

Abstract
Glioblastoma (GBM) is an aggressive form of brain cancer with a median survival of 15 months, remaining unchanged in spite of technological advances in the standard of care. The presence of the partial CMV genome, specifically in GBM cells, provides a great opportunity for a targeted therapy. We have utilized our UNITE (UNiversal Intracellular Targeted Expression) platform to build a polyvalent DNA vaccine which includes HCMV proteins, pp65, gB and IE-1. The UNITE platform is based, in part, on a lysosomal targeting technology which can result in increased antigen presentation, a balanced T cell response, and subsequent immunologic benefit. Using an orthotopic GBM mouse model expressing CMV proteins in the CT2A cell line, we have shown up to 45% survival when treated therapeutically with the pp65-IE-1 vaccine. In order to further improve the vaccine’s efficacy, and also to understand the mechanism of action, we are evaluating the post-vaccination tumor microenvironment and testing combination therapies with immune checkpoint inhibitors. Preliminary data on treated tumors suggest an increase in the PD-1 immune checkpoint regulator and a higher number of regulatory T cells. Our immune response evaluation of the polyvalent vaccine in naïve mice showed generation of robust antigen specific T cell activation. The use of multiple antigens in this vaccine makes it better suited to prevent antigen escape by tumor cells. Encouraged by our non-clinical data and the promising outcomes from our collaborators’ clinical trials using pp65 mRNA transfected autologous dendritic cells (ATTAC and ATTAC-II), we are moving forward with a phase I trial. We believe that the immune boost from our UNITE platform combined with deactivation of the immunosuppressive microenvironment by checkpoint inhibition holds a promising treatment against GBM.
DDIS-27. TARGETING ATP DOCKING AND P35/P25 BINDING OF CDK5 IN GLIOMA STEM CELLS USING SYNTHETIC INHIBITORS
Authors: Mukherjee Subhas , Schiltz Gary , Clutter Matt , Mishra Rama , Olson Cheryl , Dunder Bilge , Sharma Nitya , Markwell Steven , Brat Daniel 
Published: November 2019

Abstract
The survival advantage of glioma stem cells (GSCs) represents a critical mechanism for growth, therapy resistance and recurrence in glioblastoma. So far, targeting GSCs has not been highly specific, since these cells co-opt the normal developmental signaling pathways. We have demonstrated that the activated CDK5-CREB1 signaling axis regulates GSC self-renewal and also promotes radiation-resistance. Thus targeting CDK5 signaling is highly rational, yet there are challenges. Most of the available CDK5 inhibitors also target other CDKs non-specifically. In collaboration with The Center for Molecular Evolution and Drug Discovery, we are developing novel CDK5 inhibitors that are highly potent and specific. METHODOLOGY: The CKD5-p25 crystal structure (pdb code 1UNL) was used to conduct a virtual high throughput screen (vHTS). A library of 10 million commercially available compounds which had been filtered to ensure they possessed good drug-like properties was screened against the crystal structure. The top 33 compounds based on their predicted target binding, synthetic feasibility and availability were tested in an in vitro kinase assay to measure CDK5 inhibition. RESULTS: Of the 33 potential hit, 11 compounds showed a CDK5 inhibition of < 50 µM. These 11 hits represent 4 distinct chemical scaffolds. Two of them have IC50 < 1 µM, with one compound having an IC50 < 0.4 µM. The vHTS and subsequent in vitro testing have therefore confirmed the identification of several new series of potent CDK5 hit compounds. We are now characterizing the kinase selectivity of our different hit series and evaluating their activity in cell-based assays. This will help focus efforts on the most promising 1–2 scaffolds for further medicinal chemistry optimization to improve the compounds’ potency, selectivity and brain penetration. Ultimately, our optimized compounds will be tested in GBM models to demonstrate their effectiveness in inhibiting CDK5 as a new approach for treating GBM.
DDIS-32. MEK INHIBITORS INDUCES NEURONAL DIFFERENTIATION IN EGFR AMPLIFIED GLIOMA STEM LIKE CELLS
Authors: Balasubramaniyan Veerakumar , Park Soon , Piao Yuji , Martínez Emmanuel , Dong Jianwen , Mittal Sandeep , Khan Sabbir , Zhang Ze-yan , Sulman Erik , DeGroot John 
Published: November 2019

Abstract
The median survival for patients with glioblastoma (GBM) is 12–15 months highlighting the need for better therapeutic strategies for this deadly disease. Genomic and epigenomic sequencing analysis at the single cell level have identified multiple genomic aberrations as potential targets for therapeutic intervention in GBM. EGFR and PDGFR amplification are evident in nearly 40% and 12% of human GBM, respectively. Although the first and second-generation EGFR tyrosine kinase small molecule inhibitors failed to show long term therapeutic benefit in GBM patients, multiple factors such as incorrect patient selection, acquired resistance, and drug-target heterogeneity may all lead to clinical failure of targeted therapies. Although the multilevel genomic characterization of gliomas are increasing, the clinical translation of these findings is beginning to unravel. In this study, we attempted to correlate the genomic variations using an unbiased high throughput drug screen using primary glioma stem-like cell (GSCs) as our model system. An unbiased high-throughput screen utilizing our GSC models identified that glioblastoma cells harboring focal EGFR amplification are sensitive to mitogen-activated protein kinase (MEK) inhibitors. MEK inhibition induced apoptosis in EGFR amplified cells at low concentration. RNA sequence analysis of cells treated with MEK inhibitors revealed upregulation of genes related to neuronal differentiation and down regulation of MEK target genes in MEK sensitive glioma stem cells. Additionally, RNA sequencing of GSCs with acquired MEK inhibitor resistance demonstrated an upregulation of oncogenic transcription factor ETS Variant Gene 1 (ETV1) as a mediator of resistance. Overall our data suggest that the MEK inhibition in combination with ETV inhibitors could be a potential therapeutic target for a subset of GBM patients.
DDIS-33. SELECTIVE AND COMPLETE INHIBITION OF mTORC1 BY BI-STERIC mTOR INHIBITORS DRIVES THERAPEUTIC RESPONSE IN GLIOBLASTOMA
Authors: Wen Fan Qi , Lorenzana Edward , Luo Xujun , Lea Robin , Aksoy Ozlem , An Zhenyi , Ozawa Tomoko , Wassarman Douglas , Shokat Kevan , Aggen James , Smith Jaqueline A M , Singh Mallika , Butowski Nicholas , Raleigh David , Weiss William 
Published: November 2019

Abstract
Activation of phosphatidylinositol 3-kinase (PI3K)/PTEN pathway and oncogenic signaling via the mechanistic target of rapamycin (mTOR) occur in a majority of high-grade glial brain tumors. Allosteric mTOR inhibitors, such as rapamycin and other rapalogs, incompletely block mTORC1 by reducing phosphorylation of some substrates, including S6K1, but not 4EBP1. In contrast, ATP-competitive inhibitors, such as sapanisertib, fully inhibit mTORC1. However these inhibitors are also active against mTORC2 and lipid kinases, likely enhancing toxicity. A new class of selective mTORC1 inhibitor that interacts with both the ATP- and FKBP12/FRB-binding sites has been developed, which we term ‘bi-steric’. The prototype bi-steric inhibitor, RapaLink-1, blocks phosphorylation of many mTORC1 substrates, including 4EBP1. Importantly, RapaLink-1 showed improved efficacy in glioblastoma models in vivo as compared to rapamycin or sapanisertib (Fan et al., Cancer Cell 2017). Revolution Medicines has developed novel next-generation bi-steric mTORC1-selective inhibitors that exhibit potent and selective (>10-fold) inhibition of mTORC1 over mTORC2 in vitro in cell line models. Two of these compounds, RM-001 and RM-006, showed sustained blockade of mTORC1 signaling, including dephosphorylation of 4EBP1, following weekly ip dosing in an orthotopic U87MG-Luc model of glioblastoma. Repeated weekly administration of these agents resulted in significantly greater anti-tumor efficacy, as assessed via tumor burden (bioluminescence imaging) and overall survival in comparison to daily sapanisertib and the rapalog everolimus, and weekly dosing of the first generation bi-steric RapaLink-1, all at maximally tolerated doses. In summary, our data demonstrate that bi-steric mTORC1 selective inhibitors elict marked anti-tumor efficacy at doses that are well tolerated in a preclinical model of glioblastoma. Our study emphasizes the importance of mTOR as a central target in glioblastoma, and showcases the therapeutic potential of novel and selective clinical bi-steric mTORC1 inhibitors under development as investigational new drugs.
DRES-02. PARYLATION OF MGMT BY PARP IS REQUIRED FOR MGMT MEDIATED TEMOZOLOMIDE-INDUCED O6-METHYLGUANINE REPAIR: A NOVEL MECHANISM OF MGMT ACTION
Authors: Wu Shaofang , Gao Feng , Koul Dimpy , Yung Alfred 
Published: November 2019

Abstract
Temozolomide (TMZ) is the standard chemotherapy for malignant gliomas (MG), and resistance to this drug is mediated by the DNA repair protein O6-methylguanine-DNA methyltransferase (MGMT). Epigenetic silencing of the MGMT gene by promoter methylation in about 40% patients is associated with loss of MGMT expression that compromises DNA repair leading to favorable response to TMZ therapy. Understanding the mechanism of MGMT mediated repair and modulating MGMT activity will enhance TMZ activity in MGMT unmethylated MG. Here we report a novel mode of regulation of MGMT protein activity by Poly-ADP-ribose polymerase (PARP). We found that PAPR physically interacts with MGMT and PARylates MGMT in response to TMZ treatment. We further showed PARylation of MGMT by PAPR is required for MGMT binding to DNA and to remove O6-methylguanine adducts in damaged DNA induced by TMZ. All 4 PARP inhibitors (trapping and non-trapping) tested (Talazoparib, Pamiparib, Veliparib, Olaparib) can inhibit PARP-MGMT binding, PARylation of MGMT, binding to DNA and subsequent removal of O6 - lesions in damaged DNA. We showed combination of PARP inhibitor with TMZ potentiated TMZ cytotoxicity in both MGMT methylated and unmethylated Glioma stem cell lines, but more profoundly in unmethylated group in vitro and in vivo. PARP inhibition acted as a double-edged sword in MGMT unmethylated MG: blocking BER/SSBR pathway to repair TMZ induced N7-MetG and O3-MetA, and more importantly, suppressing PARP-mediated PARylation of MGMT and thus silencing MGMT activity to repair O6-MetG, resulting in augmented cytotoxicity. This is the first study to show that PARylation of MGMT by PARP is required for repairing TMZ-induced O6-methylguanine adducts, and inhibition of MGMT PARylation abolishes MGMT function and renders sensitization to TMZ treatment. This finding provides a rationale for combining TMZ/CCNU and PARP inhibitors in MGMT unmethylated MG patients to enhance the benefit of adjuvant chemotherapy.
DRES-04. LONG NON-CODING RNAS IN GLIOBLASTOMA TUMOR RECURRENCE AND THERAPY RESISTANCE
Authors: Stackhouse Christian , Yancey Gillespie G , Willey Christopher 
Published: November 2019

Abstract
Recurrence of therapy resistant Glioblastoma multiforme (GBM) is responsible for patient mortality. Not all patients qualify for surgical resection or for chemotherapy, but radiation is almost a universally tolerated therapy. We are modeling acquired radiation resistance using 8 radiation-sensitive GBM patient-derived xenolines (PDX) made resistant by six irradiation series (6x2Gy each) in vivo. In 4 resistance-induced PDX, MGMT (O6-methylguanine–DNA methyltransferase) protein expression increased over original isogenic PDX. Paradoxically, temozolomide screening of orthotopic radiation-resistant PDX with increased MGMT expression revealed increased, not decreased chemo-sensitivity. This suggests an unanticipated mechanism associating acquired radiation resistance and alkylating chemotherapy sensitivity. RNA-seq data of long non-coding RNAs (lncRNAs) has revealed associations with patient overall survival and age at diagnosis. Out of 24,076 lncRNAs, 5 are significantly differentially expressed with regard to patient overall survival and age at diagnosis. The functions of lnc-ZNF117-1, lnc-DCUN1D4-1, and LINC01397 are unknown, but they are enriched in brain over other tissues. Tissue specific expression and function are unknown for lnc-TBL1XR1-5, but it is highly expressed in HepG2 (hepatocellular carcinoma) as well as in non-functioning pituitary adenomas (NFPAs). The lnc-CDH17-1 transcript is also highly expressed in NFPAs. All 5 of these lncRNAs have complex secondary and tertiary structures, but their physiologic or pathologic functions are unknown. LncRNAs most likely contribute to acquired resistance through epigenetic regulation of transcription and chromatin state. Deep sequencing of total RNA isolated from intracranial radiation–sensitive/–resistant PDX to relate transcriptional programs and therapy resistance is underway. These data will be paired with kinomic profiling of matched tumors to elucidate basal signaling modality changes between radiation–sensitive/–resistant tumors. Analysis of differentially expressed lncRNA will be used to predict lncRNA structure/function, elucidating druggable mechanisms mediated by lncRNAs.
DRES-10. TEMOZOLOMIDE-ASSOCIATED HYPERMUTATION DETECTED WITH A GENE PANEL SIGNATURE IMPROVES IMMUNE RESPONSE IN GLIOBLASTOMA
Authors: Daniel Paul , Meehan Brian , Sabri Siham , Sarkaria Jann , Rak Janusz , Abdulkarim Bassam 
Published: November 2019

Abstract
Glioblastoma (GBM) is the most common and deadly type of malignant brain cancer in adults. While current standard of care which combines resection, radiation therapy (RT) and Temozolomide (TMZ) effectively eliminates primary disease, recurrence is inevitable, occurs rapidly following treatment and is ultimately lethal due to limited therapeutic opportunities of recurrent GBM. Hypermutation has been reported to occur in a subset of both low and high-grade gliomas and emerges after exposure to TMZ. Mutational inactivation and loss of mismatch repair (MMR) gene expression lead to the accumulation of single nucleotide polymorphisms throughout the genome. To date, the gain of hypermutation and subsequent therapeutic responses are still largely unknown. We hypothesized that hypermutant (HM) and non-hypermutant (NH) tumors represent two recurrent GBM subtypes, which has distinct therapeutic vulnerabilities. In addition, given the lack of concordance between microsatellite instability (MSI) and occurrence of hypermutation in GBM, we sought to derive a limited gene panel which can be used as surrogate biomarker for hypermutation following TMZ to replace whole exome sequencing (WES). Using public datasets, we demonstrated that recurrent GBM can be clustered into two subtypes: HM and NH. We used matched primary and recurrent GBM datasets to derive a gene panel signature, which is uniquely mutated at recurrence in HM GBM and confirmed the specificity of this panel in an independent dataset. Furthermore, we utilized patient derived xenograft (PDX) models to generate pre-clinical models and demonstrated that HM recurrent GBM are more immune responsive while NH recurrent GBM maintained sensitivity to a range of alternate chemotherapies such as cisplatin and RT. Finally, we demonstrated that this signature is represented in exosomes and can be enriched by use of tumor specific antibody capture methods to improve the sensitivity of hypermutation detection in liquid biopsy.
EPID-13. IDENTIFICATION OF PROGNOSTIC MARKERS IN A COHORT OF CONSECUTIVE NON-SELECTED GLIOBLASTOMA PATIENTS RECEIVING STANDARD THERAPY
Authors: Regner Michaelsen Signe , Urup Thomas , Grunnet Kirsten , Jarle Christensen Ib , Lassen Ulrik , Skovgaard Poulsen Hans 
Published: November 2019

Abstract
Glioblastoma is treated by standard with maximal surgical resection followed by radiation therapy with concomitant and adjuvant temozolomide. Still, median overall survival (OS) for glioblastoma is around 15 months, although the prognosis varies greatly. To improve the treatment, stratification of glioblastoma patients according to favorable and poor prognostic groups is needed. The aim of this study was to develop a prognostic model for glioblastoma patients treated with standard therapy outside clinical trials. The study included 680 consecutive, non-selected glioblastoma patients with WHO performance status (PS) 0–2 administered postoperative with standard first-line therapy between years 2005–2016 at the University Hospital of Copenhagen, Denmark. At disease recurrence, patients were mostly treated by reoperation and/or bevacizumab combination therapy. Patients were retrospectively evaluated by reviewing of medical records, histopathological descriptions and imaging analyses. The cohort had a median progression-free survival (PFS) of 7.5 months, median OS of 15.7 months and median OS from recurrence of 7.4 months. Comparative analyses of survival endpoints dependent on year of diagnosis did not reveal any statistically significant improvement from 2005 and forth. Factors significantly associated with worse prognosis in univariate and multivariate analyses were for OS, low extent of primary surgery, increased age, multifocal disease, increased PS and O6-methylguanine DNA methyltransferase (MGMT) tumor methylation. For PFS, multifocal disease, increased PS, and MGMT tumor methylation were significantly associated with worse prognosis. Gender, tumor location, tumor size, comorbidity score and site of tumor relapse were not significantly associated with any survival endpoints. Based on study results, a predictive model for survival will be generated able to calculate survival probability for the individual glioblastoma patient. Such a model could prove useful for stratification in clinical scientific protocols and for making glioblastoma treatment more individualized. Updated results will be presented.