bluuebunny/crossref_metadata_2025_split huggingface dataset:
CSIG-01. EPIGENETIC REPROGRAMMING DRIVES MALIGNANT PERIPHERAL NERVE SHEATH TUMOR (MPNST) DE-DIFFERENTIATION AND TREATMENT RESISTANCE
Authors: Vasudevan Harish , Lastella Sydney , Sale Matthew , Casey-Clyde Timothy , Demaree Benjamin , Delley Cyrille , Lucas Calixto , Magill Stephen , Liu John , Chen William , Braunstein Steve , Reddy Alyssa , Perry Arie , Jacques Line , Pekmezci Melike , Abate Adam , McCormick Frank , Raleigh David 
Published: November 2021

Abstract
Schwann cell derived tumors comprising schwannomas, neurofibromas, and malignant peripheral nerve sheath tumors are the most common malignancies of the peripheral nervous system. While schwannomas and neurofibromas are benign, MPNSTs are malignant, metastasize, and respond poorly to treatment. Neurofibromas and MPNSTs are associated with loss of NF1, a tumor suppressor that inhibits Ras/MEK signaling, and MPNSTs alone are distinguished by loss of the Polycomb Repressive Complex 2 (PRC2), an epigenetic regulator of methylation. To understand the genomic mechanisms of Schwann cell tumorigenesis and treatment resistance, we performed DNA methylation profiling, RNA-sequencing, and whole exome sequencing of primary Schwann cell tumor resection specimens (n=119 total: n=66 schwannoma, n=13 neurofibroma, n=40 MPNSTs). Hierarchical clustering identified three epigenetic Schwann cell tumor groups with transcriptional differences in PRC2 target genes associated with Schwann cell differentiation. Integrating biochemical and genomic approaches in primary human tumor cell lines from NF1 intact peripheral nerve, NF1 mutant neurofibromas, and MPNSTs, we found MPNST and neurofibroma cell lines with CRISPR knockout SUZ12 or EZH1/2 neurofibroma cell lines demonstrated repression of Schwann cell differentiation genes and induction of Ras signaling target genes. Further, MPNST cells deficient in PRC2 and NF1 exhibited increased basal active Ras-GTP levels, and therapeutically, PRC2 deficient MPNST cell lines were more resistant to the MEK inhibitor selumetinib and radiotherapy when compared to NF1-deficient neurofibroma cells. Single cell RNA sequencing analysis suggested distinct mechanisms of selumetinib resistance in PRC2 intact neurofibroma cells compared to PRC2-deficient MPNST cells. Taken together, our data demonstrate the importance of epigenetic dysregulation in malignant Schwann cell transformation and suggest differentiation status underlies a novel mechanism of MEK inhibitor resistance.
CSIG-02. NRF2-GUIDED GLUTATHIONE SYNTHESIS IS AN ESSENTIAL METABOLIC PATHWAY IN IN IDH1-MUTATED GLIOMA
Authors: Liu Yang , Yu Di , Yang Chunzhang 
Published: November 2021

Abstract

BACKGROUND
Isocitrate dehydrogenase (IDH) mutations are common genetic abnormalities in WHO Grade II/III glioma, which result in the reprogramming of cellular metabolism and redox homeostasis. Many lines of evidence showed that IDH mutations are critical for glioma formation, whereas the therapeutic options for IDH-mutated cancers remain limited.

METHODS
In the present study, we used the patient-derived glioma cell lines to investigate the role of nuclear factor erythroid 2-related factor 2 (NRF2) governed glutathione de novo synthesis. Further, we evaluated the therapeutic value of NRF2 inhibitors in IDH1-mutated cells and preclinical orthotopic models.

RESULTS
The neomorphic activity of mutant IDH reprogrammed the metabolic pathways involving enzyme cofactors such as nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP). The depletion of NAD(P) in IDH1-mutated cells resulted in elevated oxidative stress and constitutive activation of NRF2-governed cytoprotective pathways through the decoupling of NRF2 from its E3 ligase Kelch-like ECH-associated protein 1 (Keap1). Activation of NRF2 enhanced glutathione synthesis by enhancing the gene transcription of GCLC, GCLM, and SLC7A11, which are the critical for glutathione de novo synthesis. Further, evidence from both in vitro assays and patient cohort indicated that NRF2 governed glutathione synthesis is important for maintaining the redox homeostasis and cell survival, especially in IDH1-mutated glioma. Finally, Blockade of the NRF2/glutathione metabolic pathway exhibited synergistic cytotoxicity with the metabolic stress in IDH1-mutated cells, which results in overwhelming oxidative damage, as well as a substantial reduction in tumor cell proliferation and xenograft expansion.

CONCLUSION
In this study, we highlighted that NRF2 plays critical roles in the disease progression of IDH1-mutated glioma by prompting glutathione synthesis. Targeting NRF2 governed glutathione metabolism could serve as a valuable synthetic lethality approach for IDH1-mutated malignancies.
CSIG-07. ACTIVATION OF THE ADHESION G PROTEIN-COUPLED RECEPTOR GPR133 BY ANTIBODIES AGAINST THE N-TERMINUS
Authors: Stephan Gabriele , Frenster Joshua , Ravn-Boess Niklas , Bready Devin , Wilcox Jordan , Schöneberg Torsten , Liebscher Ines , Placantonakis Dimitris 
Published: November 2021

Abstract
We recently demonstrated that GPR133 (ADGRD1), a member of the adhesion G protein-coupled receptor (aGPCR) family, is necessary for growth of glioblastoma (GBM) and is de novo expressed in GBM relative to normal brain tissue. We therefore postulate that GPR133 represents a novel target in GBM, which merits development of therapeutics. Like most aGPCRs, GPR133 is characterized by an intracellular C-terminus, 7 plasma membrane-spanning α-helices and a large extracellular N-terminus. The N-terminus possesses a conserved GPCR autoproteolysis-inducing (GAIN) domain that catalyzes cleavage at a GPCR proteolysis site (GPS), resulting in a C-terminal fragment (CTF) and an N-terminal fragment (NTF). We showed that dissociation of the cleaved NTF and CTF at the plasma membrane increases canonical signaling of GPR133, which is mediated by coupling to Gs and increase in cytosolic cAMP. Toward characterizing the effect of biologics on GPR133 function, we overexpressed wild-type or mutant forms of GPR133 in HEK293T cells and patient-derived GBM cells lines. Treatment of these cells with antibodies specifically targeting the NTF of GPR133 increased receptor activation in a dose-dependent manner. No effects were elicited with an antibody against the receptor’s intracellular C-terminus. Interestingly, cells overexpressing a cleavage-deficient mutant GPR133 (H543R) did not respond to antibody stimulation, suggesting that the effect is cleavage-dependent. Following antibody treatment, co-purification of the GPR133 NTF and the N-terminal antibody from the cell culture supernatant indicated the formation of antibody-NTF complexes. Analysis of these complexes suggested that antibody binding stimulated the dissociation of the NTF from the CTF. However, the increased flexibility of the GAIN domain and NTF after cleavage, independently of dissociation, may also endow the receptor with responsiveness to the effects of the antibodies. These data constitute a proof-of-concept paradigm of modulation of GPR133 function with antibodies. This work provides rationale for pursuing development of biologics targeting GPR133 in GBM.
CSIG-09. ASSESSMENT OF TUMOR TREATING FIELDS (TTFields) COMBINED WITH TRICHOSTATIN A (TSA) IN PATIENT-DERIVED GLIOBLASTOMA (GBM) CELLS
Authors: Ma Manxiu , Michelhaugh Sharon , Mittal Sandeep 
Published: November 2021

Abstract

BACKGROUND
TTFields therapy is a non-invasive biophysical approach for GBM patient treatment. TTFields produce an anti-mitotic effect by destabilizing microtubule polymerization and interrupting cell division. However, epigenetic modifications that may be induced by TTFields remain unknown. To address this, TTFields were applied to patient-derived GBM cells ± the histone deacetylase (HDAC) inhibitor trichostatin A (TSA) and cellular proliferation was assessed. HDAC activity was also measured after TTFields application.

METHODS
GBM cells were isolated from a newly-diagnosed patient tumor (IDH-WT, unmethylated MGMT promoter). Cells were grown in DMEM/F12 media with 10% FBS and gentamicin. Cells were plated on plastic coverslips (1×104cells/coverslip) and incubated overnight. TTFields were applied at 200 kHz (field intensity of ~1.6 V/cm) for 6 days. For the last 2 days of TTFields, cells were incubated with DMSO or 250 nM TSA. Cells were harvested and counted to assess proliferation (n=4-5/group). To determine if TTFields have a direct effect on HDAC activity, TTFields were applied as described and nuclei were extracted. Nuclear HDAC activity was measured using a commercial kit (n=2-3/group). Cell counts were compared with one-way ANOVA and Tukey multiple comparisons with p&lt; 0.05 considered significant.

RESULTS
Cell counts for the DMSO control group, TSA only, TTFields only, and the combination were: 643,400 ± 111,384, 233,800 ± 144,200, 90,775 ± 45,209, and 41,520 ± 36,168, respectively (mean ± SD; ANOVA p&lt; 0.0001). There was no statistical difference between the TTFields only and TSA only or TTFields + TSA groups, with all other comparisons statistically significant. For the HDAC activity measurements, control nuclei were 1068 ± 135 pmol/min/mg and TTFields-treated nuclei were 1301 ± 313.6 pmol/min/mg and were not statistically different.

CONCLUSIONS
The addition of TSA to TTFields did not alter cellular proliferation more than TTFields alone and TTFields did not alter HDAC activity in these GBM cells.
CSIG-11. KINASE-DIRECTED INHIBITION OF PYRIMIDINE BIOSYNTHESIS IN PTEN-DEFICIENT GLIOBLASTOMA
Authors: Sarma Pranjal , Ennis Kelli N , Behrmann Catherine A , Wetzel Collin , Dasgupta Biplab , Plas David R 
Published: November 2021

Abstract
Targeting pyrimidine biosynthesis has been a mainstay of chemotherapy in oncology, including frontline treatment of pancreatic, breast, and colorectal carcinomas. In glioblastoma, the targeting pyrimidine biosynthesis is a promising emerging approach for counteracting the effects of PTEN-deficiency in glioblastoma. PTEN loss triggers the activation of mTORC1, which in turn phosphorylates and activates the ribosomal protein kinases S6K1 and S6K2. We have previously shown that combination treatment of inhibitors targeting S6K1 and the TYRO3-AXL-MERTK receptor tyrosine kinases (TAM-RTKs) triggers cytotoxic responses in PTEN-deficient glioblastoma cells. Here we show brain-penetrant inactivation of S6K1 and TAM-RTKs using the S6K1 inhibitor LY-2584702 and the TAM-RTK inhibitor BMS-777607, which reduced glioblastoma tumor growth. Pharmacogenetic analysis of signal transduction indicated a key role for S6K2 in sustaining survival signaling in PTEN-deficient glioblastoma cells. Steady-state metabolomics revealed that combined inactivation of S6K1 and TAM-RTKs resulted in decreased nucleotide biosynthesis, and flux analysis indicated reduced flux of glucose to pyrimidines. Altogether the results indicate a kinase-directed therapeutic strategy for targeting S6K1 and TAM-RTKs to reduce pyrimidine biosynthesis and glioblastoma tumor growth.
CSIG-17. IMMUNE MODULATORY ROLE OF TYPE I INTERFERON IN SYNGENEIC MOUSE GLIOMA MODELS
Authors: Blomberg Evelina , Silginer Manuela , Weller Michael 
Published: November 2021

Abstract
Glioblastoma is characterized by a poor prognosis and a challenging phenotype for drug development. Although multimodal treatment, including surgery, radio- and chemotherapy is applied, the overall survival remains just above one year. Numerous clinical trials have studied targeted therapies against commonly deregulated pathways, but an efficient targeted drug is yet to be discovered. Likewise, immunotherapy has not been shown to be active. A subset of glioma tumor cells demonstrates stem-like properties; these cells are commonly referred to as glioma initiating cells (GIC). These types of cells are pluripotent and can by definition initiate and recapitulate glioma growth in experimental animals in vivo. Furthermore, these cells are often resistant to conventional therapies. Interferon β (IFN-β) is an immunomodulatory molecule with anti-cancer properties. We have previously shown that IFN-β greatly reduces sphere-formation capability of GIC. It was also confirmed that IFN-β sensitized resistant GIC to irradiation or the chemotherapeutic agent, temozolomide (TMZ). IFN-β treatment significantly prolonged survival in a xenograft model with GIC cells. In the current project, we want to use syngeneic mouse models to study the immunomodulatory effects of type I IFNs. Preliminary results indicate that abrogation of IFN signalling in tumor cells by CRISPR/Cas9 technology prolonged survival in mice only in cell lines which have substantial baseline autocrine IFN signalling. On the contrary, we did not observe a difference in survival when wild-type tumor cells were implanted in either IFNAR1 deficient or proficient hosts. Flow cytometry analysis will elucidate changes in immune cell recruitment and infiltration upon IFN signalling disruption. Moreover, we explore different treatments in combination with IFN-β as there are indications that TMZ or radiotherapy can have synergistic effects with stimulation of interferon type I signalling.
CSIG-21. 5-ALA PDT AND TARGETING MEK/ERK SIGNALING ELICITS SYNERGISTIC ANTITUMOR EFFECTS IN DIFFUSE MIDLINE GLIOMA
Authors: Price Gabrielle , Rivera Daniel , Bouras Alexandros , Hadjipanayis Constantinos 
Published: November 2021

Abstract
Diffuse midline gliomas (DMGs) are highly invasive, unresectable tumors in children. To date, there is no effective treatment for DMGs. Fractionated radiotherapy (RT), currently the standard of care, has provided limited disease control. Current obstacles to treatment include the blood brain barrier (BBB) that limits systemic drug delivery, tumor therapy resistance, and brainstem infiltration. Given the unmet need for more effective DMG treatments, photodynamic therapy (PDT), with the precursor photosensitizing agent 5-aminolevulinic acid (5-ALA), is an oncologic treatment that holds promise. 5-ALA PDT of tumors occurs by targeting tumor cells that accumulate the 5-ALA metabolite, protoporphyrin IX (PPIX), with 635 nm light to create deadly reactive oxygen species (ROS). We explore the synergism of 5-ALA PDT with the MEK inhibitor, trametinib, since the RAS/MEK signaling pathway regulates tumor cell proliferation and survival and has been shown to therapeutically enhance PDT in select tumor models. We demonstrated that sub-micromolar levels of 5-ALA PDT and nanomolar levels of trametinib successfully decrease cell proliferation and induce apoptosis in multiple DMG cell lines. Cell viability assays revealed that drug response differs based on the histone mutation (H3.1 or H3.3) of the line. Mechanisms of decreased cell survival involves the generation of reactive oxygen species that induces programmed cell death. Through the use of a DMG genetically engineered mouse model, we also found 5-ALA PDT to induce apoptosis in vivo. The synergistic effects of MEK inhibition and 5-ALA PDT in vitro and apoptotic effects of 5-ALA PDT in vivo, highlights the potential therapeutic efficacy of this treatment modality.
CSIG-23. ELONGATION CONTROL OF mRNA TRANSLATION DRIVES GROUP 3 MEDULLOBLASTOMA ADAPTATION TO NUTRIENT DEPRIVATION
Authors: Delaidelli Alberto , Negri Gian Luca , Yao Betty , Wang Que Xi , Huang Yue Zhou , Hughes Christopher , Leprivier Gabriel , Sorensen Poul 
Published: November 2021

Abstract
Group 3 affiliation and MYC genetic amplification are associated with poor life expectancy and substantial morbidity in children suffering from medulloblastoma (MB). However, the high metabolic demand induced by MYC-driven transformation sensitizes MYC-overexpressing MB to cell death under conditions of nutrient deprivation (ND). Additionally, MYC-driven transformation is known to promote mitochondrial oxidative phosphorylation (OXPHOS). We previously reported that eukaryotic Elongation Factor Kinase 2 (eEF2K), the master regulator of mRNA translation elongation, promotes survival of MYC-overexpressing tumors under ND. Interestingly, eEF2K is overexpressed in MYC-driven MB and our preliminary proteomics data highlight large-scale alterations in OXPHOS components affecting eEF2K deficient MB cells. We therefore hypothesized that eEF2K activity is required for the selective translation of mRNAs needed for efficient OXPHOS, and for the progression of MYC-driven MB. We pefrormed Multiplexed enhanced Protein Dynamic Mass Spectrometry in eEF2K knockdown MYC-overexpressing D425 MB cells to identify mRNAs selectively translated upon eEF2K activation. Messenger RNAs encoding multiple (9 out of 10 detected) components of the mitochondrial OXPHOS pathway are selectively translated upon eEF2K activation. Inactivation of eEF2K by genetic KO leads to the disassembly of electron transport chain (ETC) complexes I-IV without affecting mRNA levels of their respective components. Consistently, eEF2K KO MB cells display decreased mitochondrial membrane potential and 20% increased proton leak thorough the mitochondrial membrane. In addition, eEF2K inactivation results in increased Group 3 MB cell death under ND and doubles survival of MB bearing mice fed with calorie restricted diets (p&lt; 0.05). Control of mRNA translation elongation by eEF2K is critical for mitochondrial ETC complex assembly and efficient OXPHOS in MYC-overexpressing MB, likely representing an adaptive response by which MYC-driven MB cells cope with acute metabolic stress. Future therapeutic studies will aim to combine eEF2K inhibition with caloric restriction mimetic drugs as eEF2K activity appears critical under metabolic stress conditions.
RADT-04. STEREOTACTIC LASER ABLATION (SLA) FOLLOWED BY CONSOLIDATION STEREOTACTIC RADIOSURGERY (SRS) AS A TREATMENT STRATEGY FOR BRAIN METASTASIS THAT RECURRED LOCALLY AFTER INITIAL RADIOSURGERY (BMRS)
Authors: Pena-Pino Isabela , Ma Jun , Hori Yusuki , Fomchenko Elena , Dusenbery Kathryn , Reynolds Margaret , Wilke Christopher , Yuan Yianling , Barnett Gene , Chang Verionica , Mohammadi Alireza , Chen Clark 
Published: November 2021

Abstract

INTRODUCTION
In independent clinical trials, ~30% of brain metastases recur locally after radiosurgery (BMRS). For these lesions, treatment with stereotactic laser ablation (SLA, also known as laser interstitial thermal therapy (LITT)) alone achieves a 12-month local control (LC12) of 54-85% while repeat SRS achieved LC12 of 54-79%. Here, we report favorable outcomes for BMRS treated with SLA followed by consolidation radiosurgery (SLA/cSRS).

METHODS
Clinical outcome of 18 patients with 19 histologically confirmed BMRS treated with SLA followed by consolidation SRS and &gt;3 months follow-up were collected retrospectively across three institutions. Local control was defined as stability or decrease in contrast-enhancing (CE) and FLAIR volume.

RESULTS
SLA achieved ablation of 73-100% of the BMRS CE volumes. Consolidation hypo-fractionated radiosurgery (5 Gy x 5 or 6 Gy x 5) was carried out 16-40 days post-SLA (median of 26 days). With a median follow-up of 185 days (range: 93-1367 days) and median overall survival (OS) of 185 days (range: 99-1367 days), 100% LC12 was achieved. 13/18 (72%) patients that required steroid therapy prior to SLA/cSRS were successfully weaned off steroid by three months post-SLA/cSRS. Post-SLA, KPS declined for 3/19 (16%) patients and improved for 1/19 (5%) patients. No KPS changes occurred subsequent to consolidation SRS. There were no 30-day mortalities or wound complications. Two patients required re-admission within 30 days of SRS (severe headache that resolved with steroid therapy (n=1) and new-onset seizure (n=1)). Except for two patients who suffered histologically confirmed, local failure at 649 and 899 days, all other patients are either alive (n=6) or died from systemic disease progression (n=10). None of the treated patients developed symptomatic radiation necrosis.

CONCLUSIONS
This collaborative institutional experience support efficacy and safety of SLA followed by consolidation SRS as a treatment for BMRS. The treatment strategy warrants further investigations.
RADT-12. USE OF FDOPA PET FOR RADIATION THERAPY TARGETING IN GRADE 2 IDH MUTANT GLIOMA
Authors: Cordova James , Mazur Thomas , Mitchell Timothy , Perez-Carrillo Gloria , Wang Qing , Wang Yong , Ponisio Maria , Huang Jiayi 
Published: November 2021

Abstract

BACKGROUND
Low-grade, IDH mutant (IDHmt) gliomas typically do not enhance on MRI complicating radiotherapy (RT) target delineation. Amino acid PET using 3,4-dihydroxy-6-[18F]-fluoro-L-phenylalanine (FDOPA) has demonstrated avidity in IDHmt gliomas and may assist in RT planning for non-enhancing tumors. This study aims to compare conventional and FDOPA-defined target volumes in grade 2 IDHmt gliomas.

METHODS
In a prospective pilot study, patients underwent MRI and FDOPA PET using a 3T MRI/PET system followed by standard therapy. Gross tumor volumes (GTV) included the T2/FLAIR abnormality and surgical cavity; clinical target volumes (CTV) included a 1 cm expansion constrained anatomically. Metabolic target volumes (MTVs) were generated using the FDOPA SUV &gt; 1.5-fold normal brain isocurve. Union of GTV and MTV generated a fusion GTV (fGTV); expanding fGTV by 1 cm yielded the fusion CTV (fCTV). Target volumes were compared volumetrically with overlap (Dice coefficient) and surface metrics (Hausdorff distance). Medians are reported with ranges.

RESULTS
Four patients with grade 2 IDHmt glioma (3 1p/19q codeleted oligodendrogliomas, 1 non-codeleted astrocytoma) received MRI/PET before treatment. All oligodendrogliomas exhibited FDOPA avidity; the astrocytoma showed no avidity. GTV and CTV measured 16.1 cc (4.9 - 82.2 cc) and 76.7 cc (29.5 - 256.1 cc), respectively. The MTV volume outside of GTV was 0.8 cc (0.2 – 6.1 cc), but was covered in each case by the CTV. Addition of FDOPA increased fGTV and fCTV volumes by 5.4% and 17.5%, respectively. Dice coefficient and Hausdorff distances for GTV vs fGTV were 0.96 (0.95 - 0.99) and 11.2 mm (10.0 – 11.9 mm), respectively, and for CTV vs fCTV were 0.87 (0.81 – 0.95) and 10.2 mm (10.0 - 11.0), respectively.

CONCLUSIONS
FDOPA PET identified tracer-avid regions outside of MRI-defined GTVs in a group of IDHmt gliomas. FDOPA PET provides useful metabolic information for RT planning and warrants further investigation.