bluuebunny/crossref_metadata_2025 huggingface dataset:
CBMT-05. GENETIC AND EPIGENETIC MECHANISMS REGULATING SCD INHIBITOR SENSITIVITY IN GLIOBLASTOMA
Authors: Oatman Nicole , Dasgupta Nupur , Dasgupta Biplab , Choi Kwangmin , Gawali Mruniya , Gupta Nishtha , Parameswaran Sreeja , Lawler Sean , Brennan Cameron , Wu Jianqiang , Sallans Larry , Desai Pankaj , Weirauch Matthew , Komurov Kakajan , Dasgupta Biplab
Published: November 2019

A status-quo in targeted cancer therapy is that out of the thousands of somatic alterations found in a cancer cell, alterations only in driver genes determine therapeutic strategy. Despite unimpressive results of some driver-targeted therapies, and given that the majority of genomic alterations in cancer are not ‘drivers’, but ‘passengers’ / bystander alterations, it remains underappreciated whether targeting built-in vulnerabilities imposed by passenger gene alterations may provide therapeutic value. The tumor suppressor PTEN undergoes widespread functional inactivation including deletion in human cancer. PTEN deletion occurs frequently in GBM, sometimes as part of the 10q loss or chromosome 10 monosomy. We discovered that several genes including Stearoyl Co-A Desaturase, SCD (10q24.31), located 12 MB telomeric to PTEN is frequently co-deleted hemizygously and unintentionally in PTEN-deleted cancers. Strikingly, in a subset of GBM, SCD was also epigenetically silenced. A combination of SCD deletion and methylation resulted in two molecular subgroups – one that expressed SCD, and another that showed little or no detectable SCD. SCD, is an integral membrane protein of the endoplasmic reticulum and converts saturated fatty acids to monounsaturated fatty acids (Oleic and palmitoleic acids) that are critical for membrane fluidity and function, and thus SCD is generally overexpressed in most cancers. We show that SCD expressing lines are highly sensitive to multiple SCD inhibitors, while non-expressors are resistant. Despite modest BBB penetration, one SCD inhibitor was remarkably efficient in blocking intracranial tumor growth. SCD is an oxygen-dependent enzyme. We show that SCD retains significant enzymatic activity even in highly hypoxic conditions. Finally, through RNAseq, functional proteomics and ATACseq, we demonstrate an evolutionarily conserved mechanism of acquired resistance to SCD inhibitor through drug-induced acute phase signaling response in multiple SCD expressing cancers.
CBMT-25. THE KLF4K409Q MUTATION IN MENINGIOMA IMPAIRS HIF-1Α DEGRADATION AND CAN BE HARNESSED FOR TARGETED THERAPY
Authors: von Spreckelsen Niklas , Waldt Natalie , Poetschke Rebecca , Kesseler Christoph , Dohmen Hildegard , Jiao Hui-Ke , Nemeth Attila , Deckert Martina , Angenstein Frank , Krischek Boris , Stavrinou Pantelis , Timmer Marco , Remke Marc , Kirches Elmar , Goldbrunner Roland , Chiocca Ennio , Huettelmaier Stefan , Acker Till , Mawrin Christian
Published: November 2019

Recently, several Non-NF2 driver mutations (KLF4, TRAF7, SMO, AKT1E17K) in meningioma have been identified. While they have been shown to correlate with certain pathological subtypes and locations, the clinical impact and repercussions on cellular pathways have largely remained elusive. Through analysis of clinical, pathological and preoperative imaging data of 96 patients and sequencing of the corresponding 96 tumor samples for the Krueppel like factor 4-K409Q mutation (KLF4K409Q) we present evidence that the KLF4K409Q tumors harbour an increased risk for peritumoral brain edema (PTBE) and can be predicted with the edema-index, a simple tool based on preoperative imaging. Further analysis involving RNA-sequencing of a matched subset of 7 KLF4K409Q and 10 KLF4-wildtype (wt) tumors revealed a significant shift of gene expression and the upregulation of hypoxia driven pathways, including VEGF levels, in KLF4K409Q tumors. On the cellular level, we go on to show that the KLF4K409Q mutation results in an increased KLF-4 stability as well as the inhibition of hydroxylation dependent degradation of HIF1-α and a significant increase of VEGF expression under hypoxic conditions. Finally, we demonstrate that this upregulation of VEGF in KLF4K409Q cells can be inhibited by targeting the mammalian target of rapamycin (mTor) with Temsirolimus. In summary we show that the KLF4K409Q mutation in meningioma has highly relevant repercussions in both, the biological and clinical context and can be harnessed for targeted therapy.
CBMT-28. FATTY ACID OXIDATION PROVIDES METABOLIC PLASTICITY TO MAINTAIN GROWTH IN THE DYNAMIC MICROENVIRONMENT OF GLIOBLASTOMA
Authors: Kant Shiva , Kesarwani Pravin , Prabhu Antony , Graham Stewart , Buelow Katie , Nakano Ichiro , Chinnaiyan Prakash
Published: November 2019

Glioblastoma represents an aggressive, primary brain tumor with limited treatment options. Despite advances in molecularly characterizing glioblastoma, metabolic alterations driving its aggressive phenotype are only beginning to be recognized. Integrative cross-platform analyses coupling global metabolomic and gene expression profiling identified alterations in fatty acid β-oxidation (FAO) as a key metabolic node differentiating glioblastoma from low-grade astrocytoma, which was defined by an accumulation of acylcarnitines. Metabolic heterogeneity was observed within glioblastoma that could further define tumors as FAO ‘high’ and ‘low’, which were enriched with mesenchymal and proneural subtypes of glioblastoma, respectively. These findings were metabolomically and functionally recapitulated in molecular subtype-specific preclinical models, with the majority of baseline mitochondrial oxygen consumption being a result of enhanced FAO in these cells. The biologic consequence of enhanced FAO in glioblastoma is directly dependent upon tumor microenvironment. FAO serves as a metabolic cue to drive proliferation in a β-HB/GPR109A/cAMP-dependent autocrine manner in nutrient favorable conditions while providing an efficient, alternate source of ATP only in nutrient unfavorable conditions. Accordingly, inhibiting FAO alone in glioblastoma cells with etomoxir only led to modest anti-proliferative activity and minimal cytotoxicity. However, rational combinatorial strategies designed to target the dynamic roles FAO plays in gliomagenesis resulted in metabolic synthetic lethality in glioblastoma. Specifically, dual targeting of FAO (etomoxir) and glycolysis (2DG) resulted in robust energetic stress, necroptosis mediated cell death, and a significant improvement in survival in an orthotopic glioblastoma mouse model. In summary, we identified FAO as a dominant metabolic node in glioblastoma that provides metabolic plasticity, allowing these cells to adapt to their dynamic microenvironment. Combinatorial strategies designed to target these diverse roles FAO plays in gliomagenesis offers therapeutic potential in glioblastoma.
CBMT-38. THERAPEUTIC INHIBITION OF THE SPLICEOSOME IN GLIOBLASTOMA: CHANGES FORM MINOR TO MAJOR
Authors: Bonifert Tobias , Arora Sonali , Fitzgibbon Matthew , Paddison Patrick
Published: November 2019

Chemical or genetic perturbation of the spliceosome function may represent a therapeutic opportunity for Glioblastoma multiforme (GBM) and other cancers. We and others have shown that oncogenic MYC activity causes spliceosome vulnerability and leads to deficits in 3’ splice site recognition upon spliceosome perturbation. Several spliceosome inhibitors in pre-clinical development and in clinical trials target the U2 snRNP subcomplex SF3B, which is essential for 3’ splice site recognition. We showed that knockdown of one of its subunits, PHF5A, causes GBM-specific changes in splicing, including increases in exon skipping, intron retention and activation of alternative 3’ and 5’ splice sites. However, in depth analysis of these events revealed they are disproportionately enriched for “minor” introns. This class of ~800 introns is specifically excised by an alternative splicing pathway which involves the U12-dependent spliceosome. Remarkably, we provide evidence that inhibition of PHF5A in GBM stem-like cells causes increased retention of most minor introns, as well as activation of cryptic and alternative U2 snRNP-dependent splicing sites. We further demonstrate that components of the U12 snRNP complex are differentially required for GSC-specific viability. Our results suggest that regulation of the splicing of U12-type introns may be critically important for GBM tumor cell viability.
CBMT-45. SEX-SPECIFIC METABOLIC ADAPTIONS IN GLIOBLASTOMA
Authors: Sponagel Jasmin , Zhang Shanshan , Chinnaiyan Prakash , Rubin Joshua , Ippolito Joseph
Published: November 2019

Glioblastoma (GBM) is the most common and aggressive brain tumor in adults. GBM occurs more commonly in males, but female patients survive significantly longer. Understanding the molecular mechanisms that underlie those sex differences could support novel treatment strategies. In this regard, we found that male and female GBM patient samples differ in their metabolite abundance and that male patients exhibit a significantly higher abundance of TCA cycle metabolites. We confirmed those findings in a murine model of GBM, which has previously yielded important insights into sexual dimorphism in GBM. Strikingly, sex differences in TCA cycle flux were entirely driven by glutamine flux, not glucose flux, suggesting a sex-specific role for glutamine in GBM. Metabolic manipulation through glutamine deprivation resulted in a greater growth inhibition in male GBM cells. Glutamine itself can be utilized for anabolic reactions or it can be converted to glutamate by glutaminase. Only male GBM cells were sensitive to pharmacological glutaminase inhibition with BPTES or CB-839, suggesting that male GBM cells are glutamate dependent while female GBM cells are not. Concordantly, we found significantly higher glutaminase levels in male GBM cells. Furthermore, we found that numerous metabolites (including NADH, ATP, and glutathione) involved in cellular processes downstream of glutamate were more abundant in male GBM cells. In contrast, female GBM cells were resistant to low glutamine conditions and glutaminase inhibitors unless glutamine-synthase activity was disrupted, suggesting that glutamine synthesis might play a more prominent role in female GBM. Together, these data indicate that male and female GBM differ in their metabolic adaptions. Male GBM utilize glutamate to fuel the TCA cycle and mitochondrial activity while female GBM synthesize and utilize glutamine itself. This sexual dimorphism in metabolic reprogramming reveals novel sex specific metabolic targets for GBM and underlines the importance of considering sex in metabolic targeting approaches.
CSIG-21. DE-ORPHANIZING GPR133 - AN ADHESION GPCR REQUIRED FOR GLIOBLASTOMA PROGRESSION
Authors: Frenster Joshua , Erdjument-Bromage Hediye , Stephan Gabriele , Chidambaram Shravanthi , Alghamdi Abdulhakeem , Bready Devin , Straeter Norbert , Liebscher Ines , Schoeneberg Torsten , Neubert Thomas , Placantonakis Dimitris
Published: November 2019

We previously found GPR133 (ADGRD1), an orphan adhesion GPCR, is de novo expressed in glioblastoma (GBM) and enriched in patient-derived glioblastoma stem cells (GSCs). Knockdown of GPR133 reduces GBM cell proliferation and tumorsphere formation, and abolishes orthotopic tumor initiation in vivo in mice. Analysis of TCGA data indicates that increased GPR133 transcription inversely correlates with patient survival in GBM. While these findings underscore the importance of GPR133 in GBM and suggest an essential role in tumor growth, its ligand and mechanism of activation remain unknown. Toward identifying GPR133 ligands, we used GPR133’s N-terminal ectodomain as bait and performed affinity co-immunoprecipitation (CoIP) followed by mass spectrometry as an unbiased screening approach. We identified 490 extracellular proteins with enriched binding to GPR133 compared to control. Reverse CoIP using the 15 most abundant candidate ligands as bait to purify the receptor confirmed this interaction reproducibly in 4 candidates. Despite this binding, overexpression of these candidate ligands, or addition of purified recombinant protein, is not sufficient to increase receptor signaling as assessed by cAMP levels in HEK293 cells. This suggests that ligand binding to the GPR133 ectodomain may not be sufficient by itself to induce receptor activation. We hypothesize receptor activation requires mechanical forces in addition to ligand binding. Consistent with this hypothesis, the GPR133 binding proteins we have identified may be anchored to the extracellular matrix, mediating such mechanical force. To test whether mechanical shearing of the extracellular domain is sufficient for receptor activation, we used Dynabeads coupled to antibody against GPR133’s N-terminal ectodomain, and indeed observed receptor activation leading to elevated cAMP levels. No activation was observed when Dynabeads devoid of antibody were used. This mode of GPR133 activation might indicate a role in sensing mechanical/viscoelastic properties of GBM extracellular matrix, which may be relevant to tumor cell migration and invasion.
CSIG-22. REGULATION OF GLIOMA STEM CELL SELF-RENEWAL AND TUMORIGENESIS BY CARBOHYDRATE BINDING PROTEINS
Authors: Sharanek Ahmad , Fatakdawala Idris , Jahani-Asl Arezu
Published: November 2019

Glioma Stem Cells (GSC) are a population of malignant self-renewing stem cells in glioblastoma (GBM) tumors, the most common and aggressive primary brain tumor in the adult brain. GSC promote tumor growth and recurrence and acquire resistance to therapy. Strategies to target GSC in the tumor bulk are urgently needed in order to develop more effective therapeutic strategies for GBM. EGFRvIII/STAT3 signaling is a major oncogenic pathway in GBM. Here, we report our discovery that Galectin1, a family member of carbohydrate-binding proteins with affinity for b-galactosides, promotes GSC self-renewal and tumor growth in EGFRvIII-expressing subset of tumors. Analysis of RNA-Seq data shows that LGALS1, the gene encoding Galectin1, is highly expressed in human EGFRvIII-expressing GSC and its expression correlates with the expression of transcription factor STAT3. Importantly, STAT3 directly binds the promoter of LGALS1 to upregulate its expression and knockdown of STAT3 significantly attenuates LGALS1 mRNA levels. Genetic knockdown of LGALS1 impairs the ability of GSC to form spheres, as assayed in limiting dilution assay, suggesting that LGALS1-STAT3 signaling regulates glioma stem cell fate in EGFRvIII tumor subset. Strikingly, we employed genetic and pharmacological approaches in patient derived xenografts and found that LGALS1/Galectin1 impairs gliomas stem cell growth and tumorigenesis. Subcutaneous and stereotactic intracranial implantation of CRISPR knockout LGALS1 EGFRvIII-expressing GSC into SCID mice showed significantly reduced in vivo tumor xenografts growth and increased survival rate compared with controls. Treatment of GSC with OTX008, a specific inhibitor of galectin-1, significantly attenuates the self-renewal ability of these cells and impairs tumorigenesis. Together, our findings suggest that targeting LGALS1/Galectin1 in combination with current standards of care may provide an effective strategy for the future treatment of these deadly brain tumors.
CSIG-31. ALTERNATIVE RECEPTOR TYROSINE KINASE SIGNALING AS A RESISTANCE MECHANISM TO ERK INHIBITION IN HIGH-GRADE GLIOMAS
Authors: Stanton Ann-Catherine , Koncar Robert , Golbourn Brian , Wassell Michelle , Agrawal Nishant , Dey Brittany , Myers Max , Mack Stephen , Pollack Ian , Agnihotri Sameer
Published: November 2019

Pediatric High-Grade Gliomas (PHGG), which include Diffuse Midline Gliomas (DMG), are a leading cause of brain tumor death in children. Our recent work has identified extracellular signal-regulated kinase 5 (ERK5) as a critical mediator of cell survival in PHGG. Suppression of ERK5 genetically or pharmacologically leads to decreased cell proliferation and increased apoptosis both in vitro and in vivo in multiple PHGG and H3K27M mutant DMG cell lines. Mechanistically, we show that ERK5 directly stabilizes the proto-oncogene MYC at the protein level, providing rationale to clinically target ERK5. ERK5 contains both a kinase domain (KD) and a transactivation domain (TAD), unlike all other ERKs. Unexpectedly, we found that our ERK5 depleted cells could be partially rescued by an ERK5 kinase domain dead (ERK5-KDD) but TAD intact construct. Additionally, persistent ERK5 depletion does not result in complete growth inhibition and therefore we set out to determine potential adaptation or resistance mechanisms in response to ERK5 loss. To address this, we performed RNA sequencing of DMG cells, comparing control cells to ERK5 knockdown cells, and performed gene-ontology (GO) pathway analysis to identify transcriptional changes that occur in response to ERK5 depletion. We identified 105 differentially expressed genes, and GO analysis identified alternative receptor tyrosine kinase (RTK) gene-expression as one of the top biological processes upregulated in response to ERK5 loss. We validated our top targets at the RNA and the protein level. Our top targets were Erb-B2 Receptor Tyrosine Kinase 4 (ERBB4) and Discoidin Domain Receptor Tyrosine Kinase 2 (DDR2), both clinically actionable targets. Our future work will focus on functional validation of these RTKs as potential resistance mechanisms to ERK5 loss. Identification of resistance mechanisms to ERK5 loss will have both biological and translational relevance and may lead to effective therapeutic combinations.
CMET-04. RADIOMICS FEATURES CAN DIFFERENTIATE THE EGFR MUTATION STATUS OF BRAIN METASTASES FROM NON-SMALL CELL LUNG CANCER
Authors: Won Park Yae , Soo Ahn Sung , Choi Dongmin , Kim Hwiyoung
Published: November 2019

BACKGROUND AND PURPOSE

To assess whether radiomics features on DTI and conventional postcontrast T1-weighted (T1C) images can differentiate the epidermal growth factor receptor (EGFR) molecular status in brain metastases from non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

Radiomics features (n = 5046) were extracted from preoperative MRI including T1C and DTI from pathologically confirmed brain metastases of 59 patients with underlying NSCLC and known EGFR mutation status (31 EGFR wild type, 28 EGFR mutant). A subset of 4317 features (85.6%) with high stability (intraclass correlation coefficient > 0.9) were selected for further analysis. After feature selection by the least absolute shrinkage and selection operator, the radiomics classifiers were constructed by various machine learning algorithms. The prediction performance of the classifier was validated by using leave-one-out cross-validation. Diagnostic performance was compared between multiparametric MRI radiomics models and single imaging radiomics models using the area under the curve (AUC) from ROC analysis.

RESULTS

Thirty-seven significant radiomics features (6 from ADC, 6 from fractional anisotropy [FA], 25 from T1C) were selected. The best performing multiparametric radiomics model (AUC 0.97, 95% CI 0.94–1) showed better performance than any single radiomics model using ADC (AUC 0.79, p = 0.007), FA (AUC 0.75, p = 0.001), or T1C (AUC 0.96, p = 0.678); the accuracy, sensitivity, and specificity of this model were 94.4%, 96.6%, and 92.0%, respectively.

CONCLUSION

Radiomics classifiers integrating multiparametric MRI parameters may be useful to differentiate the EGFR mutation status in brain metastases from lung cancer.
CMET-11. RESPONSE TO STEREOTACTIC RADIOSURGERY FOR MULTIPLE BRAIN METASTASES BASED ON HISTOLOGY-SPECIFIC SUBTYPE STATUS
Authors: Rooney Michael K , Chandler James , Kalapurakal John , Stupp Roger , Lesniak Maciej S , Sonabend Adam , Kumthekar Priya , Tate Matthew , Kruser Timothy , Lukas Rimas , Dixit Karan , Sachdev Sean
Published: November 2019

BACKGROUND

This retrospective study evaluated the relationship between histologic subtype and treatment outcomes following SRS for the treatment of multiple brain metastases (MBM).

METHODS

We analyzed patients with MBM, defined here as >= 3 lesions, treated with SRS at our institution. Primary histologies examined were NSCLC, breast, and melanoma. Patients were categorized according to histology-specific subtypes (NSCLC-EGFR, ALK, KRAS, PD-L1%; breast-HER2, ER, PR; melanoma-BRAF). The primary outcome was local control (defined by RANO-BM) and secondary outcomes included intracranial progression-free survival (iPFS) and overall survival (OS).

RESULTS

141 patients met inclusion criteria (66 NSCLC, 61 breast, and 14 melanoma). HER2+ and BRAF V600E+ lesions had increased rates of local control following SRS (P=0.0048 and P=0.0256, respectively) compared to other breast/melanoma subtypes. EGFR mutation was not associated with increased local control with SRS (71 vs 74%), but increased iPFS (P=0.0031). On multivariable analysis, EGFR+ was independently associated with a decreased time-dependent risk of death (P=0.011). The use of progressively newer generations of EGFR-directed therapies was associated with stepwise decreasing risk of intracranial progression and death. HER2+ disease had improved iPFS and OS (P=0.0058 and P< 0.0001, respectively; it was not an independent risk factor for progression or death; however, the use of HER2-directed antibodies was associated with decreased risk of death (p=0.036). The use of tyrosine kinase inhibitors (i.e. lapatanib) was not associated with improvements, although this was a small subset.

CONCLUSIONS

Some histologic subtypes appear to have better control with SRS, with HER2+ breast cancer and BRAF V600E+ melanoma associated with improved outcomes – this requires further validation; a volumetric analysis is pending. This the protective effect of EGFR mutation appears to be partly related to use of EGFR inhibitors, with the use of newer-generation therapies leading to improved outcomes; although local control with SRS remains excellent regardless of the mutation.
CMET-17. RENAL CELL CARCINOMA BRAIN METASTASES TREATED WITH STEREOTACTIC RADIATION THERAPY AND NIVOLUMAB DOES NOT ALTER LESIONAL OR CLINICAL OUTCOMES
Authors: Mohammadi Homan , Tolpin Aaron , Figura Nicholas , Peacock Jeffrey , Oliver Daniel , Sim Austin , Palm Russel , Ahmed Kamran , Liu James , Tran Nam , Etame Arnold , Vogelbaum Michael , Robinson Timothy , Yu Michael
Published: November 2019

Metastases (BM) carries the risk of hemorrhaging lesions and can be effectively treated using stereotactic radiotherapy (SRT). Nivolumab is a recently approved immunotherapy for stage IV RCC. We evaluate whether patients with RCC BM treated with SRT overlapping with nivolumab have altered clinical and BM outcomes. METHODS: 38 consecutive patients were identified in our retrospective database from 1/2011 to 6/2018. Analyses were performed on a per-lesional basis (n=170), per-treatment session basis (n=79), and per-patient basis (n=38). Patients who received nivolumab within 6 months of SRT were considered to have overlapping treatments. ROC curve, chi-squared, Kaplan-Meier, log-rank, and Cox regression model were employed for statistical analyses. RESULTS: A total of 7 (18.4%) patients received overlapping treatments for 64 (37.6%) eligible lesions. Median follow-up was 15.4 months and median overall survival from first BM treatment was 14.8 months (0.5 – 98.4). Median time to subsequent distant brain and non-brain failures were 3.4 and 2.2 months, respectively. Median time to local failure was 20.2 months (two lesions). There were 11 hemorrhagic toxicities (7 in the nivolumab group) and 17 radionecrosis toxicities (4 in the nivolumab group) with no significant difference amongst the groups. Lesions receiving nivolumab within 6 months of SRT did not exhibit a higher rate of toxicity (p=0.521) but had a shortened time to hemorrhage (p< 0.001). Patients who received SRT > 1 month after nivolumab had a prolonged time to subsequent distant brain failure (median 11.1 months) than patients who received SRT > 1 month before (median 3.1 months) or within 1 month (median 1.6 months) of nivolumab, p=0.014. CONCLUSIONS: Overlapping nivolumab with SRT is safe with no increased risk of hemorrhagic lesions. An optimal treatment sequence of nivolumab administration followed by SRT prolongs the time to subsequent BM and warrants further investigation.
CMET-20. ANALYSIS OF NANO-SIZED PARTICLE IN HUMAN CEREBROSPINAL FLUID: A MEASUREMENT OF EXTRACELLULAR VESICLE CONCENTRATION CHANGE WITH MIR-21 EXPRESSION AFTER CHEMOTHERAPY FOR LEPTOMENINGEAL CARCINOMATOSIS
Authors: Lee Kyue-Yim , Lin Wei-wei , Gwak Ho-Shin , Heon Kim Jong , Chul Yoo Byong , Kim Tae-Hoon , Bae Park Jong , Jin Park Hyeon , Kim Ho-Jin , Woong Kwon Ji , Hoon Shin Sang , Yoo Heon
Published: November 2019

PURPOSE

For comparing the distribution and concentrations of nano-sized micro-molecules in cerebrospinal fluid (CSF) according to different central nervous system (CNS) disease

METHODS

We have collected CSF of 447 patients from 6 different groups (systemic cancer, healthy control, leptomeningeal carcinomatosis (LMC), brain metastasis, other brain tumor, and other CNS disease). After cell down by centrifugation, proportion of nano-sized particle is measured by Nano-sizer and absolute number of extracellular vesicle (EV, 100–1,000 nm) is counted by Nano-sight. We verified exosomes in our CSF samples by exosome purification and Western blot.

RESULTS

In Nano-sizer, two peaks appeared at mean 10.5 nm and 174 nm. The small peak is presumed to be nucleic acid and protein as we could decrease or eliminate the peak by nucleic acid elimination kit or proteinase. The proportion of large peak, presumed to represent EVs, is significantly higher in LMC group than all other groups (mean 64% vs. 44%, p < 0.001). And also, the count of EV is significantly higher in patients with LMC (7.15 x 108 vs. 3.46 x 108, p < 0.001). Furthermore, we evaluated paired EV concentration of pre- and post-treatment of intra-CSF chemotherapy in non-small lung cancer patients with LMC (n=33). Overall survival of patients was significantly prolonged in patients with increased EV count compared to those of decreased or ‘no-change’ (< 20%) (442 vs. 165 days, p < 0.001). The expression level of onco-microRNA (miR-21) is decreased significantly after the treatment in this favorable prognostic group (p < 0.01).

CONCLUSION

We expect to obtain appropriate variables representing cancer cell activity in the CSF samples by observing this nano-sized molecule proportion and EV concentration with onco-miR expression. KEY WORDS: cerebrospinal fluid, exosome, extracellular vesicle, microRNA, leptomeningeal carcinomatosis
CMET-24. PLATEAU WAVE EVENTS: A COMMON, CURABLE, AND ROUTINELY MISDIAGNOSED SYNDROME IN PATIENTS WITH NEOPLASTIC MENINGITIS (NM)
Authors: Padmanaban Varun , Zammar Samer , Zacharia Brad , Rizk Elias , Ryan Sandra , Glantz Michael
Published: November 2019

INTRODUCTION

NM is defined clinically by multilevel neurologic dysfunction. Seizures occur in less than 15% of patients. We describe a curable phenomenon (“plateau wave events”) that mimics and may be more common than seizures, but is not responsive to anticonvulsant medication.

METHODS

We queried a multinational NM registry to identify patients with episodic neurologic dysfunction suspected of having seizures. Detailed demographic, disease, treatment, and outcome data were collected.

RESULTS

Forty-three patients (21.2% of 203) were identified. Twenty patients (46.5% of 43) demonstrated a stereotyped constellation of symptoms including episodic severe headache and loss (19 patients) or impaired level (1 patient) of consciousness, nausea, vomiting, and gait instability lasting 30–180 seconds, with abrupt resolution and without post-ictal symptoms. Events developed a median of 74 (0–350) days following NM diagnosis. Fourteen patients (74%) were female. Median age was 54.8 [IQR 46.8, 61.6] years. Fourteen patients had solid tumors (11 breast), 5 had hematologic malignancies, and 1 had a primary brain tumor. Thirteen (68%) had ventriculomegaly. All patients demonstrated increased ICP [median 30.0 cm H2O, IQR 22.5, 30.0]. CSF cytology was positive and CSF protein was increased in 100% of patients, but no demographic, laboratory, or disease characteristic was associated with plateau wave events on multivariate analysis. Inter-ictal EEG in 8 patients showed no epileptiform activity. One intra-ictal EEG showed marked brainwave slowing and bradycardia during the clinical event. One intra-ictal ICP tracing showed an abrupt and dramatic increase in intracranial pressure during the event. Nineteen patients underwent ventriculoperitoneal shunting and experienced immediate symptom resolution. Anticonvulsant medication, initiated in 11 of these patients prior to shunting, provided no benefit.

CONCLUSIONS

Plateau wave events are common in patients with NM. They are frequently mistaken for seizures but are easily recognized by a constellation of defining signs and symptoms. Ventriculoperitoneal shunting is curative.
CMET-32. DNA METHYLATION ALTERATIONS IN LUNG ADENOCARCINOMAS THAT DEVELOP BRAIN METASTASES
Authors: Zuccato Jeffrey , Mamatjan Yasin , Aldape Kenneth , Zadeh Gelareh
Published: November 2019

INTRODUCTION

The development of brain metastases from primary cancer profoundly impacts patient prognosis. Metastases are the most common adult brain tumor with up to one quarter of lung cancers developing metastases and median overall survival after metastasis being one year. Clinical factors do not reliably predict brain metastasis development and over 90% are identified after symptoms develop. DNA methylation signatures predict outcomes in other cancers and so identifying signatures that predict metastasis development may allow for treatment strategies that prevent development in high risk patients.

METHODS

Whole genome DNA-methylation profiling was undertaken on N=124 lung adenocarcinoma patients after bisulfite conversion of DNA from formalin-fixed paraffin-embedded tissue. In a randomly selected 70% training cohort, the most differentially methylated CpG sites between patients developing and not developing brain metastases were identified with p< 0.05. A generalized boosted regression model built on these selected features output brain metastasis risk scores for patients in the independent 30% testing cohort.

RESULTS

Brain metastases developed in 49/124 (39.5%) of patients and 2.3K CpG sites were significantly differentially methylated between patients developing and not developing metastases. Methylation-based brain metastasis risk scores predicted time to brain metastasis in a univariate cox regression model (HR=3.2, 95% CI 1.1–9.4, p=0.03). A corresponding area under the receiver operating characteristic curve at 52 months was 0.64. A multivariate cox analysis including tumor size and nodal status, representing the non-metastatic components of cancer stage, identified methylation score as the only independent predictor of brain metastasis (HR=4.3, 95%CI 1.1–17, p=0.038).

CONCLUSIONS

DNA methylation signatures in lung adenocarcinoma predict brain metastasis development independent of stage components, which classically predict patient outcome in cancer. Future work developing a comprehensive nomogram utilizing methylation scores together with other clinical factors to determine patient specific risk values may aid in treatment decisions and patient prognosis counselling.
CMET-33. PHASE II STUDY OF PALBOCICLIB IN BRAIN METASTASES HARBORING CDK PATHWAY ALTERATIONS
Authors: Brastianos Priscilla , Cohen Justine , Wang Nancy , Lee Eudocia , Ligibel Jennifer , Chukwueke Ugonma , Keeley Maura , Oh Kevin , White Michael , Gerstner Elizabeth , Batchelor Tracy , Lawrence Donald , Ryan David P , John Iafrate A , Giobbie-Hurder Anita , Flaherty Keith , Santagata Sandro , Carter Scott , Cahill Daniel , Sullivan Ryan
Published: November 2019

BACKGROUND

Up to 25% of all cancer patients will develop brain metastases and prognosis remains poor. In preclinical work, we discovered that more than 50% brain metastases genomically diverge from primary tumors and harbor alterations in genes involved with cell cycle regulation. We thus initiated a phase II study to evaluate the efficacy and safety of the cyclin dependent kinase (CDK) 4/6 inhibitor, palbociclib, in patients with recurrent brain metastases with alterations in the CDK pathway (NCT02896335).

METHODS

The primary endpoint of the trial is the rate of intracranial benefit (defined as CR, PR, or SD, per RANO) at 8 weeks after the start of palbociclib. A Simon two-stage design was used to compare the rate of intracranial benefit for a null rate of 10% against an alternative of 30%. Fifteen patients were to be enrolled in the first stage. If fewer than 2 responders were observed, then the study would stop for insufficient evidence of efficacy. If 6 or more responders were observed among the total of 30, this treatment regimen would be considered worthy of further study. CSF, blood samples and tumor samples were collected to elucidate the genomic determinants of response to CDK inhibitors in the brain.

RESULTS

A total of 14 patients have been accrued (5 with breast cancer, 4 with melanoma, 3 esophageal and 2 with non-small cell lung cancer) thus far. One or more grade-3 or higher adverse events at least possibly related to treatment were seen in six (42%) patients, the majority being hematologic toxicities. At the time of the data analysis, eight (57%) patients had achieved intracranial benefit. Therefore, the study met primary endpoint.

CONCLUSIONS

In this unique, genomically-guided brain metastasis trial, we demonstrate that the CDK 4/6 inhibitor, palbociclib, is well-tolerated and has activity in patients with brain metastases.
COMP-03. QUANTITATIVE IMAGE FEATURE ANALYSIS IN DIFFUSE GLIOMA – A VALUABLE MR IMAGING BIOMARKER FOR PREOPERATIVE IDH MUTATION CLASSIFICATION
Authors: Carver Eric , Snyder James , Griffith Brent , Wen Ning
Published: November 2019

INTRODUCTION

Pre-operative differentiation of IDH mutant gliomas from similar appearing pathologies on imaging prior to definitive surgical diagnosis may aid treatment navigation, maximize the surgical approach, and provide diagnostic support for inoperable tumors. Quantitative image feature analysis offers a potential non-invasive method to identify diagnostic, prognostic, and predictive imaging biomarkers. We investigated the use of radiomic MR imaging features to classify tumors based on IDH mutation status.

METHOD

Pre-operative T1-weighted (T1W), T2-weighted (T2W), T1-contrast enhanced (T1CE), and fluid attenuated inversion recovery (FLAIR) MR brain images, along with patient IDH mutation status (mutant/wildtype) were obtained for 128 glioma patients from The Cancer Genome Atlas (TCGA). Enhancing tumor was delineated by GLISTRboost. GlistrBoost is a hybrid-discriminative model that segments tumors based on an expectation-maximization framework with a classification scheme and uses a probabilistic Bayesian strategy for segmentation refinement. MR studies for 78 glioma patients from six institutions were used for training and 50 glioma patients from a different institution were used for validation. Pre-processing included registration, resampling, and normalization. Cancer Imaging Phenomics Toolkit (CaPTK) extracted 938 radiomic image features per sequence for the enhancing tumor contour. Relevance of each individual feature was determined by the least absolute shrinkage and selection operator (LASSO). The ability of relevant radiomic image features to identify mutation status of IDH was assessed by logistic regression.

RESULTS

LASSO identified one highly informative radiomic imaging feature, the minimum of the mean absolute histogram deviation on T1 MR images, which was able to predict IDH mutation status with an accuracy of 0.74, precision of 1.0, and recall of 0.32.

CONCLUSION

Non-invasive prediction of IDH mutation status from pre-surgical MR images offers potential diagnostic, therapeutic, and prognostic benefits for glioma patients. Quantitative image feature analysis is a feasible method for identifying potential radiomic imaging features.
COMP-14. MOLECULAR PROFILING AND CELLULAR DECONVOLUTION OF GLIOBLASTOMA BRAIN TUMORS USING CHROMATIN RUN-ON AND SEQUENCING
Authors: Chu Tinyi , Rice Edward , Salamanca Hans , Wang Zhong , Longo Sharon , Corona Robert , Viapiano Mariano , Chin Lawrence , Danko Charles
Published: November 2019

Glioblastoma is among the most heterogeneous malignancies, making difficult the identification of clinically-relevant interactions between tumor cells and their supportive tumor microenvironment. Moreover, whether the heterogeneity of tumor cells is reflected by changes in the composition of the tumor microenvironment remains poorly defined. To further understand the cellular heterogeneity of GBM, we used our previously validated chromatin run-on and sequencing (ChRO-seq) method to analyze 61 GBMs from a retrospective cohort of patients banked at the State University of New York (Upstate Medical Center) between 1987 and 2007 (characteristics: Male:Female ratio= 2:1; median age at diagnosis= 59 years; median KPS=80; median overall survival= 343 days). We developed a new Bayesian statistical model that uses transcription at cell-type specific enhancers to identify the cellular composition of the tumor microenvironment in each patient. We validated our tool using simulations and scATAC-seq data from the same specimens, showing large improvements in sensitivity and accuracy compared with CYBERSORT. Integrative analysis of cellular composition and matching clinical data revealed correlations between the presence of specific cell types in the tumor mass and clinical variables. Finally, our analysis allowed us to identify transcription factors (e.g., NF-kB, C/EBPB) that control gene expression changes, revealing which cell types are controlled by each transcription factor in the GBM microenvironment. Our study uncovers new insights into the cellular heterogeneity of GBM and its impact on clinical progression and survival.
COMP-17. LARGE-SCALE TRANSCRIPTOMIC CHARACTERIZATION OF PRIMARY AND RECURRENT GLIOBLASTOMA IDENTIFIES GENE EXPRESSION SIGNATURE OF TUMOR RESPONSE TO STANDARD THERAPY
Authors: Dhawan Andrew , Lathia Justin , Peereboom David , Barnett Gene , Yeaney Gabrielle , Ahluwalia Manmeet
Published: November 2019

A near-universal phenomenon in glioblastoma is disease recurrence following surgical resection and chemoradiotherapy. Development of biomarkers predictive of therapeutic response to better guide care and inform future targeted therapies is crucial. In this work, a total of 84 glioblastoma surgical specimens involving 44 primary tumors and 40 matched samples at time of re-resection, were characterized utilizing RNA-sequencing. Transcriptomic analysis was carried out with the goal of identifying underlying differences between those patients with prolonged response to standard therapy and delayed time to re-resection. We examined individual gene expression, gene coexpression networks, and well-known gene pathways in this dataset that showed consistent association with time to re-resection in both primary and progressed specimens, independent of tumor molecular subtype. Leveraging this large, well-characterized dataset, and using a novel computational methodology based on a seed-gene approach, we identified a predictive gene signature for therapeutic response. Our analyses revealed a striking degree of heterogeneity among gene expression associated with response to standard therapy and time to re-resection, adding to the complexity of signature derivation. The novel signature we obtained for response showed components involving genes such as those in the IGF pathway (IGF2BP2, IGF2BP3) and PDGF-signalling pathway (MYC, FLI1, ARHGAP4, JAK3) predictive of poor response to therapy. Likewise, predictors of positive response to therapy included genes involved in the apoptosis and RAS pathways (RAB4A, CHUK) and DNA replication pathways (SSBP2). In sum, this is among the largest cohorts of well-characterized clinical tumor samples for which there is transcriptomic information from primary and re-resected samples from matched patients. Our results not only highlight an innovative computational method for gene signature derivation in the setting of significant underlying heterogeneity, but also result in a predictive gene signature, offering the potential to give therapy to those who stand to benefit most.
DDIS-02. DEVELOPMENT OF NOVEL SPRAY-TYPE FLUORESCENT PROBES FOR GLIOBLASTOMA DETECTION
Authors: Kitagawa Yosuke , Tanaka Shota , Kuriki Yugo , Yamamoto Kyoko , Nejo Takahide , Takahashi Satoshi , Nomura Masashi , Hana Taijun , Koike Tsukasa , Kushihara Yoshihiro , Yamazawa Erika , Takayanagi Shunsaku , Mukasa Akitake , Kamiya Mako , Urano Yasuteru , Saito Nobuhito
Published: November 2019

PURPOSE: ALA is commonly used as an intraoperative tool in malignant glioma surgery, which has been proven effective for radical tumor resection and extended progression-free survival. However, there are some limitations in its use, such as false positivity, false negativity, and inability of re-administration. We aim to develop a novel fluorescent labeling system which can be repeatedly administered by spray during surgery, using hydroxymethyl rhodamine green (HMRG) as fluorescent scaffold originally designed at our university for cancer detection. [Methods]Primary probe screening was performed using the homogenized glioblastoma (GBM) samples with the fluorescent probe library comprised of more than 320 kinds of HMRG fluorescent scaffold combined with various types of dipeptides. Second probe screening was performed using fresh GBM specimens and the selected probes in primary screening. To identify the responsible enzymes, diced electrophoresis gel (DEG) assay was performed. This method utilizes the combination of two dimensional electrophoresis (isoelectric point and molecular weight) and a multiwell-plate-based fluorometric assay to find protein spots with the specified activities. [Results] The prominent probes were selected based upon the above two-step screenings. We identified two enzymes by proteome analysis and experiments using inhibitors, which was further confirmed with real-time PCR and western blotting. [Discussion] This screening methodology is innovative in that it is based on selecting probes from the probe library that respond to clinical samples rather than creating probes from the responsible enzymes. Practical fluorescent probes can be established even for low-grade gliomas, which would be a breakthrough for rapid intraoperative diagnosis in glioma surgery. [Conclusion] HMRG-based aminopeptidase fluorescent probes may be effective for GBM detection.
DDIS-04. INTERFERON-β SENSITIZES HUMAN GLIOBLASTOMA CELLS TO THE CYCLIN-DEPENDENT KINASE INHIBITOR, TG02
Authors: Le Rhun Emilie , Lohmann Birthe , Epskamp Mirka , Weller Michael
Published: November 2019

Novel treatments for glioblastoma, the most common malignant primary brain tumor, are urgently needed. Type I interferons (IFN) are natural cytokines primarily involved in defense against viral infections, but may also play a role in the control of cancer, notably in the suppression of the cancer stem cell phenotype. TG02 is a novel orally available cyclin-dependent kinase 9 inhibitor which induces glioma cell apoptosis without profound caspase activation and is currently being explored in early clinical trials in newly diagnosed and recurrent glioblastoma. Here we used human glioma-initiating cell line models to explore whether IFN-β modulate the anti-glioma activity of TG02. Pre-exposure to IFN-β sensitized human glioma models to a variable extent to subsequent exposure to TG02. Combination treatment was associated with increased DEVD-amc cleaving activity that was blocked by BCL2. However, BCL2 did not protect from the synergistic effects of IFN and TG02 on glioma cell growth, furthermore, although IFN strongly induced pro-apoptotic XIAP-associated factor (XAF) expression, disrupting XAF expression did not abrogate the synergy with TG02 either. Consistent with that, caspase 3 gene silencing did not abrogate effects of TG02 or IFN-β alone or in combination. Finally, we observed that IFN-β may indeed modulate the effects of TG02 up-stream in the signaling cascade since inhibition of RNA polymerase II phosphorylation, a direct readout of TG02 pharmacodynamic activity, was facilitated in glioma cells pre-exposed to IFN-β. In summary, these data suggest that type I IFN may be combined with TG02 to limit glioblastoma growth but the well characterized effects of IFN and TG02 on apoptotic signaling are dispensable for synergistic control of tumor growth. Instead, exploring how IFN signaling primes glioma cells for TG02-mediated direct target inhibition may help to design novel, more effective pharmacological approaches to glioblastoma.
DDIS-25. PENTAMIDINE; A NEW CHEMOTHERAPY TARGETING ON GLIOMA STEM LIKE CELLS
Authors: Tamai Sho , Jiapaer Shabierjiang , Zhang Guangtao , Zhang Jiakang , Wang Yi , Sabit Hemragul , Tanaka Shingo , Kinoshita Masashi , Hirao Atsushi , Nakada Mitsutoshi
Published: November 2019

INTRODUCTION

Glioblastoma (GBM) is the most common primary malignant brain tumors. Despite aggressive therapies, median overall survival of patients who suffered from GBM is only 18 months. Furthermore, there is no effective therapy for glioma stem cells (GSCs), which act as forming tumors. Herein, we newly identified pentamidine, an antiprotozoal drug, is effective for GSCs by using drug repositioning approach.

METHOD

We used patient-derived glioma stem like cell lines KGS01, KGS07 which were established at Kanazawa University. We investigated proliferation ability, stemness and intracellular signal change by proliferation assay, sphere forming assay and western blotting, respectively. RESULT: Proliferation ability was prohibited by pentamidine in both cell lines. The half maximal inhibitory concentration was 1 - 5 μM. Sphere forming assay revealed that size and number of spheres were reduced in both cell lines, depending on concentration of pentamidine. Phosphorylation of extracellular signal-related kinase (ERK) and signal transducer and activator of transcription 3 (STAT3) were suppressed by pentamidine.

DISCUSSION

Pentamidine is known as the therapeutic drug for pneumocystis jirovecii. In this study, pentamidine suppressed proliferation activity and stemness in both glioma stem cell lines. Previous papers revealed pentamidine had anti-tumor effects for some types of tumor cell lines, however, therapeutic effect for tumor stem cells have never been mentioned.

CONCLUSION

These results suggest that pentamidine would be therapeutic drug for GSCs by suppressing phosphorylation of ERK and STAT3.