bluuebunny/crossref_metadata_2025_split huggingface dataset:
EXTH-01. INHIBITION OF DNA-PKcs BY M3814 POTENTIATES EFFICACY OF IONIZING RADIATION IN PATIENT-DERIVED XENOGRAFTS OF MELANOMA BRAIN METASTASES
Authors: Ji Jianxiong , Smith Emily , Sarkaria Paige , Mladek Ann , Talele Surabhi , Swanson Katelyn , Mohammad Afroz S , Zhang Wenjuan , He Lihong , Hu Zeng , Zhao Yu , Chen Jiajia , Connors Margaret A , Porath Kendra A , Bakken Katrina K , Dragojevic Sonja , Carlson Brett L , Gupta Shiv K , Burgenske Danielle M , Kitange Gaspar J , Elmquist William F , Sarkaria Jann 
Published: December 2020

Abstract
Radio-resistance mechanisms limit the benefit of radiation therapy (RT) for melanoma brain metastases. A key pathway for radiation-induced DNA double-strand break repair is non-homologous end joining, which is critically mediated by DNA-dependent protein kinase (DNA-PKcs). Here we evaluated radio-sensitizing effects of M3814, a selective oral inhibitor of DNA-PKcs, in patient-derived xenografts (PDXs) of melanoma brain metastases. In a clonogenic survival assay, M3841 augmented RT-induced killing of M12 cells at concentrations of ≥300 nM, and a minimum of 16 h exposure with ~300 nM M3814 was required for effective sensitization. M3814 inhibited RT-induced (5 Gy) auto-phosphorylation of serine-2056 of DNA-PKcs in primary cultures of M12, M15 and M27 PDX lines. Interestingly, inhibition of RT-induced DNA-PKcs by M3814 coincided with increased KAP1 phosphorylation, a DNA damage signaling regulated via ATM. Persistent γH2AX foci were observed in 28% M12 cells at 24 hours after co-treatment with M3814 and RT as compared to 12% cells following RT alone. In vivo pharmacokinetic analysis after single oral dose of 20 mg/kg M3814, showed reasonably short half-life (~2.44 hours) and poor brain distribution in wild-type FBV mice (Kpuu, 0.027). Consistent with an efflux liability, brain distribution of M3814 in triple knockout mice for BCRP/MDR1A/B was ~11 fold higher (Kpuu, 0.215). Compared to normal brain, much higher M3814 concentrations were detected in intracranially implanted M12 tumors (~23 fold and ~20 fold) 2 and 6 hours after a single oral dose of 50mg/kg respectively. The relative exclusion of M3814 from normal brain as compared to brain metastases suggests that this drug may have a favorable toxicity profile when combined with radiation for treatment of melanoma brain metastases, and this hypothesis is being tested in ongoing efficacy studies.
EXTH-05. NON-CYTOTOXIC RADIATION ENHANCES DELIVERY OF ANTISENSE OLIGONUCLEOTIDES AND IMPROVES CHEMO-RADIATION EFFICACY IN BRAIN TUMOR XENOGRAFTS
Authors: Wu Jeffrey , Holland Samantha , Muldoon Leslie , Neuwelt Edward , Ambady Prakash 
Published: December 2020

Abstract
Overexpression of O6-methylguanine DNA methyltransferase (MGMT) contributes to brain tumor chemo-resistance. Previously we found that non-cytotoxic radiation improved anti-MGMT Morpholino Oligonucleotides (AMONs) delivery to reduce MGMT levels in subcutaneous tumor xenografts. Here we evaluated if radiation enhanced the delivery of intravenous (IV) AMONs to rat brain and improved chemo-radiation therapy (CRT) efficacy using rat models of human brain tumors. Athymic nude rats bearing orthotopic cerebellar D283 medulloblastoma or intracerebral H460 non-small cell lung carcinoma (NSCLC) brain metastasis xenografts were used. The impact of cranial radiation on delivery of IV 3’-carboxyfluorescein labeled oligonucleotides across the neurovascular unit was evaluated using confocal microscopy. We found that high brain parencymal fluorescence in radiated compared to non-radiated rats. MGMT protein silencing was assessed by immunoblot in tumor-bearing rats 3 d after 2 Gy cranial radiation alone or followed in 1 d by IV AMONs (10.5 mg/kg). Radiation followed by AMONs reduced MGMT expression by 50% in both xenograft models. To evaluate efficacy, tumor-bearing rats received one dose of 2 Gy radiation plus oral temozolomide (20 mg/kg x 4d) with or without IV AMONs. AMONs concurrent with CRT reduced tumor volumes in the medulloblastoma model (p=0.012), and a similar trend was found in the NSCLC brain metastasis model. In conclusion, we demonstrate the use of a single clinically relevant radiation dose fraction to guide and enhance the delivery of oligonucleotides into brain tumor xenograft models to reduce MGMT levels and improve CRT efficacy.
EXTH-10. COMBINATION OF EPIGENETIC ENZYME INHIBITORS, GSK-J4 AND BELINOSTAT, REVEALS HIGH EFFICACY IN IDH1 MUTANT GLIOMAS
Authors: Kayabolen Alisan , Sahin Gizem Nur , Seker Fidan , Cingoz Ahmet , Isik Bekir , Acar Simge , Wakimoto Hiroaki , Cahill Daniel , Solaroglu Ihsan , Cribbs Adam , Oppermann Udo , Bagci-Onder Tugba 
Published: December 2020

Abstract
Mutations in IDH1 and IDH2 genes are common in low grade gliomas and secondary GBM and are known to cause a distinct epigenetic landscape in these tumors. To interrogate the epigenetic vulnerabilities of IDH-mutant gliomas, we performed a chemical screen with inhibitors of chromatin modifiers and identified 5-azacytidine, Chaetocin, GSK-J4 and Belinostat as potent agents against primary IDH1-mutant cell lines. Testing the combinatorial efficacy of these agents, we demonstrated GSK-J4 and Belinostat combination as a very effective treatment for the IDH1-mutant glioma cells. Engineering established cell lines to ectopically express IDH1R132H, we showed that IDH1R132H cells adopted a different transcriptome with changes in stress-related pathways that were reversible with the mutant IDH1 inhibitor, GSK864. The combination of GSK-J4 and Belinostat was highly effective on IDH1R132H cells, but not on wt glioma cells or nonmalignant fibroblasts and astrocytes. The cell death induced by GSK-J4 and Belinostat combination involved the induction of cell cycle arrest and apoptosis. RNA sequencing analyses revealed activation of inflammatory and unfolded protein response pathways in IDH1-mutant cells upon treatment with GSK-J4 and Belinostat conferring increased stress to glioma cells. Specifically, GSK-J4 induced ATF4-mediated integrated stress response and Belinostat induced cell cycle arrest in primary IDH1-mutant glioma cells; which were accompanied by DDIT3/CHOP-dependent upregulation of apoptosis. Moreover, to dissect out the responsible target histone demethylase, we undertook genetic approach and demonstrated that CRISPR/Cas9 mediated ablation of both KDM6A and KDM6B genes phenocopied the effects of GSK-J4 in IDH1-mutant cells. Finally, GSK-J4 and Belinostat combination significantly decreased tumor growth and increased survival in an orthotopic model in mice. Together, these results suggest a potential combination epigenetic therapy against IDH1-mutant gliomas.
EXTH-21. INTRAINFUSION CATHETER MOVEMENT FACILITATES INCREASED INFUSATE VOLUME DISPERSED IN AGAROSE GEL
Authors: Mehta Jason , McRoberts Gabrielle , Rylander Christopher 
Published: December 2020

Abstract
Glioblastoma has a 5 year survival of only 5.5% and a median patient survival of 12 to 15 months even with gold standard treatment. One potential method of improving treatment of glioblastoma is the use of convection-enhanced delivery (CED) which utilizes local delivery of therapeutics to the brain. However, clinical trials have shown an inability of standard catheters to deliver therapeutics to the entire target area. In this study, we explore the potential of controlled catheter movement to increase the volume dispersed (Vd) of indigo carmine dye in agarose gel brain tissue phantoms. We use four catheter control protocols: stationary, continuous retraction, continuous insertion, and intermittent insertion using a single port stepped catheter. The continuous retraction group resulted in consistent catheter clogging caused by the continued insertion of the catheter and therefore was removed from further analysis. Vd and backflow distance was quantified for all other catheter movement protocols using optical images captured throughout the infusion. Catheter retraction resulted in an increase in Vd of 51% while intermittent insertion resulted in a Vd increase of 24% compared to the stationary catheter. Additionally, a 37% reduction in backflow distance was seen with the retracting catheter when compared to the stationary catheter. These results are further supported by a simplified computational model that we have created. The computational model simulates the infusion of indigo carmine dye through an agarose gel brain tissue phantom and shows an increase in Vd of over 100% with catheter retraction. The increased Vd and decreased backflow distance afforded by the retracting catheter, suggests that the use of catheter movement may be a useful technique in increasing drug dispersal in tumorous tissue. Additional work in live and excised tissue should be conducted to confirm these results and an exploration of optimal needle movement protocols is necessary.
EXTH-23. MULTIVALENT TARGETED CYTOLYTIC AGENTS FOR GLIOBLASTOMA TREATMENT
Authors: Sharma Puja , Herpai Denise , Roberts Callie , Fokt Izabela , Priebe Waldemar , Tatter Stephen , Rossmeisl John , Debinski Waldemar 
Published: December 2020

Abstract
Glioblastoma (GBM) complexity and heterogeneity requires treatment that addresses those pathobiological features. We have been developing selective cytotoxic agents able to target at the same time several GBM-associated factors. The chosen targets are responsible for the disease progression and/or recurrence as well as for resistance to the existing therapies. As a proof of concept, a Phase I clinical trial of a cytotoxic cocktail targeting IL-13RA2 and EphA2 receptors demonstrated dramatic anti-tumor responses in dogs with spontaneous gliomas that represent the closest translational model to human disease. To this end, we have developed multivalent agents that target four receptors specific to GBM: IL-13RA2, EphA2, EphA3, and EphB2, the combined expression of which covers virtually the whole tumor microenvironment. We have designed a multivalent protein termed QUAD 3.0 that contains an IgG1 scaffold, ephrinA5, which is a ligand for the EphA2, EphA3, and EphB2 receptors, and IL-13.E13K, a mutated version of interleukin 13 (IL-13), which binds preferentially to IL-13RA2. In QUAD 3.0, there is a cysteine at the C-terminal end of the protein to allow site-specific conjugation to cytotoxic cargo. QUAD 3.0 bound effectively to the four receptors in vitro and in vivo. QUAD 3.0 was conjugated to a modified form of Pseudomonas Exotoxin A (PE38QQR) and highly potent DNA binding agents based on modified doxorubicin (WP936, WP1737 and WP1244). All conjugates were highly cytotoxic to established and primary GBM cells with IC50s &lt; 50 nM. We also treated the first dogs with QUAD 3.0-PE38QQR and QUAD 3.0-WP936 at a dose of 1.6 mg/ml using real-time monitored convection-enhanced delivery and observed up to 60% of tumor shrinkage and long-term survival. Thus, multivalent targeted agents demonstrate highly promising anti-tumor activity as single pharmaceutical, off-the-shelf agents. We also expect that our targeted drug candidates produce immune responses against tumors amplifying their cytolytic anti-tumor effect
EXTH-24. INCREASING THERAPEUTIC INDUCED NEURAL STEM CELL PERSISTENCE IN THE GLIOBLASTOMA TUMOR RESECTION CAVITY
Authors: Bomba Hunter , Sheets Kevin , Carey-Ewend Abigial , Goetz Morgan , Findlay Ingrid , Bago Juli , Hingtgen Shawn 
Published: December 2020

Abstract

BACKGROUND
Induced neural stem cells (iNSCs) have emerged as a promising therapeutic platform for glioblastoma (GBM). iNSCs have the innate ability to home to tumor foci, making them ideal carriers for anti-tumor payloads. However, iNSC persist for only two weeks in the murine GBM tumor resection cavity. We hypothesized that, by encapsulating iNSCs in a scaffold matrix, we could increase both the persistence of the cells the therapeutic durability.

METHODS
iNSCs expressing TRAIL were encapsulated in a gelatin-thrombin matrix; fibrinogen was used to polymerize the matrix. SEM was used to explore interactions between iNSCs and the scaffold matrix. To evaluate persistence, iNSCs encapsulated in the matrix were implanted into mock resection cavities of athymic nude mice and followed via BLI. To study the impacts of encapsulation on iNSC efficacy, athymic nude mice were implanted with U87 or GBM8 tumors. Tumors were then resected, and iNSCs encapsulated in the matrix were implanted; tumor volume was monitored via BLI.

RESULTS
SEM images showed homogeneous distribution of iNSCs throughout the matrix; iNSCs were completed encased in the fibrin clot component of the matrix and did not adhere to gelatin. In vivo, encapsulated iNSCs persisted for nearly 100 days whereas iNSCs directly injected into the brain parenchyma persisted &lt; 20 days. Using mice bearing GBM8 tumors, animals treated with a high dose of therapeutic encapsulated iNSCs survived ~60 days longer than animals treated with non-therapeutic cells. A similar trend was observed in animals inoculated with U87 tumors. While not statistically significant, 25% of mice treated with iNSCs encapsulated in the gelatin-thrombin matrix survived longer than those treated with iNSCs encapsulated in a fibrin-only matrix, suggesting additional benefit due to the gelatin component.

FUTURE DIRECTIONS
Prospective experiments will explore the impact of the scaffold on iNSC phenotype, including proliferation, differentiation, and migration markers.
EXTH-30. EXPANDING THE UTILITY OF PRE-CLINICAL CONTRAST ENHANCED CT (CE-CT) FOR TUMOR DETECTION IN ORTHOTOPIC GBM MODELS USING RADIOMICS
Authors: Connor Kate , Conroy Emer , White Kieron , Shiels Liam , Gallagher William , Keek Simon , Ibrahim Abdalla , Clerkin James , O’Brien David , Lambin Philippe , Woodruff Henry , Byrne Annette 
Published: December 2020

Abstract
Despite magnetic resonance imaging (MRI) being the gold-standard imaging modality in the glioblastoma (GBM) setting, the availability of rodent MRI scanners is relatively limited. CT is a clinically relevant alternative which is more widely available in the pre-clinic. To study the utility of contrast-enhanced (CE)-CT in GBM xenograft modelling, we optimized CT protocols on two instruments (IVIS-SPECTRUM-CT;TRIUMPH-PET/CT) with/without delivery of contrast. As radiomics analysis may facilitate earlier detection of tumors by CT alone, allowing for deeper analyses of tumor characteristics, we established a radiomic pipeline for extraction and selection of tumor specific CT-derived radiomic features (inc. first order statistics/texture features). U87R-Luc2 GBM cells were implanted orthotopically into NOD/SCID mice (n=25) and tumor growth monitored via weekly BLI. Concurrently mice underwent four rounds of CE-CT (IV iomeprol/iopamidol; 50kV-scan). N=45 CE-CT images were semi-automatically delineated and radiomic features were extracted (Pyradiomics 2.2.0) at each imaging timepoint. Differences between normal and tumor tissue were analyzed using recursive selection. Using either CT instrument/contrast, tumors &gt; 0.4cm3 were not detectable until week-9 post-implantation. Radiomic analysis identified three features (waveletHHH_firstorder_Median, original_glcm_Correlation and waveletLHL_firstorder_Median) at week-3 and -6 which may be early indicators of tumor presence. These features are now being assessed in CE-CT scans collected pre- and post-temozolomide treatment in a syngeneic model of mesenchymal GBM. Nevertheless, BLI is significantly more sensitive than CE-CT (either visually or using radiomic-enhanced CT feature extraction) with luciferase-positive tumors detectable at week-1. In conclusion, U87R-Luc2 tumors &gt; 0.4cm3 are only detectable by Week-8 using CE-CT and either CT instrument studied. Nevertheless, radiomic analysis has defined features which may allow for earlier tumor detection at Week-3, thus expanding the utility of CT in the preclinical setting. Overall, this work supports the discovery of putative prognostic pre-clinical CT-derived radiomic signatures which may ultimately be assessed as early disease markers in patient datasets.
EXTH-32. TARGETED STAT3 INHIBITION IMPAIRS MDSC MOBILIZATION AND RECRUITMENT IN GLIOBLASTOMA
Authors: von Roemeling Christina , Li Chenglong , Mitchell Duane 
Published: December 2020

Abstract

BACKGROUND
Glioblastoma tumors (GBM) are comprised upwards of 30 percent by glioma-associated myeloid cells (GAMs). A large fraction of GAMs are myeloid-derived suppressor cells (MDSC) thought to traffic in from peripheral circulation. MDSCs foster a hospitable environment for cancer cells by regulating immune suppression and driving resistance to immunotherapy. While signal transducer and activator of transcription 3 (STAT3) is considered to be a specific marker for MDSCs and is a known player in their phenotypic polarization in cancer, we sought to closely examine its specific role in MDSC trafficking and tumor recruitment.

HYPOTHESIS
Targeted inhibition of STAT3 blocks MDSC from the bone marrow, mitigating their accumulation within GBM tumors.

METHODS
Human and murine GBM samples were analyzed for immune-specific STAT3 phosphorylation (P-STAT3). Immune cell characterization and quantification in peripheral and GBM tissue from syngeneic murine models treated with a novel STAT3 inhibitor (LLL12B) was done. Therapeutic responses to LLL12B alone and in combination with immune checkpoint blockade were evaluated.

RESULTS
We found P-STAT3 to be predominantly expressed by tumor-associated immune cells in both human and murine GBM, particularly MDSCs. Circulating numbers of MDSCs dramatically increase in response to tumor burden. P-STAT3 is elevated in these cells, indicating that its activation occurs prior to tumor infiltration. LLL12B blockade of STAT3 significantly reduced the number of circulating and tumor-infiltrating MDSCs. As a single agent LLL12B reduced tumor volume and extended the survival of murine GBM models. When combined with anti-PD-1 checkpoint blockade, we observed durable survival in a significant fraction of treated mice.

CONCLUSIONS
These findings advocate a critically important role for STAT3 in regulating MDSC mobilization and trafficking to GBM tumors. It additionally reveals a new therapeutic mechanism of action for LLL12B that may be relevant for other direct inhibitors of STAT3, influencing their clinical applicability to treat GBM.
EXTH-35. SYNERGISTIC EFFECT OF TARGETING THIOREDOXIN REDUCTASE (TRX1) AND DEPLETION OF GLUTATHIONE SYSTEM (GSH) IN GLIOBLASTOMA STEM CELLS
Authors: Jamali Fatemeh , Daniel Paul , Petrecca Kevin , Abdulkarim Bassam , Sabri Siham 
Published: December 2020

Abstract
Glioblastoma (GBM), the most common and advanced malignant primary brain tumor in adults remains incurable. GBM tumor recurrence occurs within a short time reflecting the failure to eradicate chemo-radioresistant GBM stem cells (GSCs). GSCs alter the redox system including Thioredoxin (Trx) and glutathione (GSH) systems to counteract increased reactive oxygen species (ROS). We previously showed the role of O6-methylguanine-DNA methyltransferase (MGMT) in response to PRIMAMET, a drug that targets the TP53 tumor suppressor gene and decrease Thioredoxin reductase1 (TRxR1) levels and further identified a positive relationship between MGMT and TrxR1 in established GBM cell lines isogenic for MGMT. Auranofin (Au), an orally available ROS-inducing FDA-approved drug is a potent irreversible inhibitor of TrxR1. The effect of Au on GSCs and the potential relationship between TrXR1, MGMT and p53 specifically in GSCs remain unknown. We hypothesized that increased ROS levels in GSCs might affect their drug resistant phenotype. we investigated the cytotoxic effects of Au on GSCs with known MGMT and P53 status and the mechanisms underlying these effects. Our results suggest that Au exerts strong cytotoxic effects in GSCs within a micromolar range. These effects were associated with increased ROS levels, decreased TrXR1, MGMT, phosphorylation of ERk1/2, activation of p53 and increased apoptosis, we also used a knockdown strategy to assess the role of p53 and showed that increased sensitivity to Au for p53-knockdown. We showed the role of ROS in response to Au using ROS inducer L-Buthionine Sulfoxamine (L-BSO), a GSH inhibitor, and ROS scavenger N-Acetylcysteine (NAc). L-BSO combined with Au drastically decreased the IC50 within a nanomolar range suggesting the crucial role of both Trx and GSH systems in GSCs redox balance. Increased ROS with concomitant GSH depletion using L-BSO might circumvent drug-induced oxidative stress and overcome drug resistance in MGMT-positive and negative GSCs
EXTH-54. ENHANCED SENSITIVITY OF HUMAN GLIOMA CELLS FOR TEMOZOLOMIDE (TMZ) BY COMBINING THERAPY WITH HEAT SHOCK PROTEIN 90
Authors: Sharma Pratibha , Mahadevan Lakshmi Shree K , Argall Aaron , Xu Jihong , Sampath Deepa , Puduvalli Vinay 
Published: December 2020

Abstract

BACKGROUND
Heat-shock protein 90 (HSP90) is a molecular chaperone involved in the conformational maturation of many client proteins that regulate cell proliferation, survival, and apoptosis. Due to the limited solubility of natural Hsp90 inhibitors, synthetic inhibitors with a more potent impact are being developed. In this study we examined the biological activity of a potent synthetic small molecule Hsp90 inhibitor, SNX-5422 (PF-04929113)and assessed its ability of to inhibit the growth of glioma and to synergize with temozolomide. We also examined the ability of SNX-5422 to cross the blood brain barrier (BBB) and to achieve target inhibition in vivo.

METHODS
Using a combination of in vitro techniques, the effect of SNX-5422 on the biological impact and HSP90 client protein signaling were studied in glioma lines and patient-derived glioma stem like cells. Its efficacy as a single agent or in combination with TMZ was also assessed in vitro. To assess SNX-5422 ability to cross blood brain barrier, brain and plasma pharmacokinetics was performed in non-tumor bearing mice.

RESULTS
SNX-5422 exhibited potent growth inhibition in both glioma cells and GSCs with an IC50 range of 100-500nM, and inhibited pro-survival signal kinases, phospho-Akt, p-ERK1/2 and p-S6 following treatment in GSC262 and GSC811. This was accompanied by accumulation of apoptotic cells following SNX-5422 exposure. Combination studies with TMZ showed a synergestic impact on glioma cell proliferation. Pharmacokinetics studies showed a significant drug penetrance into the intact brain further supported by elevated levels of HSP70 (molecular maker for HSP90 inhibition) by IHC.

CONCLUSIONS
SNX-5422 is effective in downregulating Hsp90 client proteins required for glioma cell survival. In addition, SNX-5422 inhibits tumor growth by promoting apoptosis through modulation of several key signaling pathways and sensitizes glioma cells to TMZ. Given also that SNX-5422 crosses BBB, it warrants further investigation as a clinical agent for treatment of gliomas.