bluuebunny/crossref_metadata_2025 huggingface dataset:
BIOM-47. PREDICTORS OF SEIZURE AT ONSET USING A FUNCTIONAL VARIANT ANALYSIS OF TARGETED NEXT GENERATION SEQUENCING IN GBM
Authors: Lim-Fat Mary Jane , Rahman Rifaquat , Iorgulescu Bryan , Bhave Varun , Youssef Gilbert , Allen Marie , Chukwueke Ugonma , McFaline-Figueroa J Ricardo , Nayak Lakshmi , Lee Eudocia , Reardon David A , Batchelor Tracy , Beroukhim Rameen , Huang Raymond , Bi Wenya Linda , Ligon Keith , Wen Patrick Y
Published: November 2022

BACKGROUND

Adverse events (AE) including seizures cause significant morbidity in patients with GBM. We propose a novel method for assessing genomic predictors of AEs using results from a clinical targeted sequencing platform with variant function analysis.

METHODS

We identified 1,011 consecutive adult patients with newly diagnosed, histologically confirmed IDH-wildtype GBM with targeted exome NGS (Oncopanel) at Dana-Farber Cancer Institute from 2013-2019. Seizure at presentation was retrospectively identified as an AE. Biologic function (high loss, low loss, neutral, low gain and high gain) was assigned to variants using a three-tiered approach leveraging a genetic variant database (OncoKB), followed by analysis using protein prediction tools (Sift, Polyphen2 and Provean). Univariate logistic regression was performed for each relevant altered gene against the outcome of interest with false-discovery rate correction. Genes associated with seizure at presentation were included iteratively in a multivariate logistic model including other predictors of the outcome.

RESULTS

Our analysis included 470 GBM patients with 107 genes and 12 whole chromosome or arm level candidate variants covered by all versions of Oncopanel and with >10% alteration. Seizure at presentation occurred in 143/463 patients (31%) and was associated with EGFR amplification (high gain) (OR: 2.76, 95% CI: 1.4-5.3, p = 0.04). In a multivariate analysis (including age, sex, and preoperative tumor volume), EGFR amplification remained statistically significant (OR: 1.5, 95% CI: 1.0-2.2, p = 0.03).

CONCLUSION

Genomic biomarkers based on functional variant analysis of a routine clinical panel may predict adverse events in GBM. Seizure at presentation was independently associated with EGFR amplification. Our ongoing analysis will look at predictors of myelosuppression, thromboembolism, pseudoprogression and early progression using a similar approach. Identifying molecular risk factors could improve the management of patients through supportive care and consideration of prophylactic therapies.
BIOM-51. ELUCIDATION OF THE TRANSCRIPTOMIC CONSEQUENCES OF KLF4 AND TRAF7 MUTATIONS IN SECRETORY MENINGIOMAS
Authors: Michaelsen Signe Regner , Cloos Paul , Broholm Helle , Johansen Jens , Ahmadov Ulvi , Mathiesen Tiit , Kristensen Lasse , Kristensen Bjarne Winther , Hansen Klaus
Published: November 2022

Secretory meningioma (SM) is a benign histological meningioma subtype frequently located in the central skull-base, complicating surgical removal, highlighting the need of gentle targeting treatment alternatives. SM tumors arise from the arachnoid layer in the meninges and are associated with a hotspot p.K409Q mutation in KLF4 combined with different mutations in TRAF7. The objective of this study was to identify how KLF4 and TRAF7 mutations alter signaling in SM tumors.The study includes 16 FFPE samples from SM tumors and three arachnoid cysts as normal-tissue reference. All tissues were histologically confirmed, followed by genomic sequencing of KLF4, TRAF7, NF2 and TERT-promoter (C220T/C228T) using a customized NGS panel. Gene expression profiles were analyzed using NanoString Pan-cancer Progression and Pan-cancer Pathways panels, which resulted in measurement of 1,202 unique transcripts over background level.All 16 SM tumors presented the KLF4p.K409Q mutation, of which 12 had mutation in TRAF7 (four being p.N520S), while no cysts had mutations in these genes. Neither tumors nor cysts had NF2 or TERT-promoter mutations. PCA analysis showed different RNA expression profiles for SM tumors and cysts, while TRAF7 mutation was without influence on the overall gene expression patterns in the tumors. Sub-analysis found increased KLF4 expression in TRAF7-mutated SM tumors versus non-mutated tumors and cysts at the RNA level, while TRAF7 expression was stable in all samples. In total 98 genes were found differentially expressed (54 up- and 44 downregulated) with a log2-fold change over 1 and an adjusted p-value under 0.05 in tumors versus cysts. Further analyses are planned to explore and validate these results. In conclusion, we find that the KLF4p.K409Q mutation correlates more strongly with SM histology, than the TRAF7 mutation, and that SM tumors have gene expressions profiles that are distinct from normal arachnoid tissue for a number of disease relevant genes.
BIOM-53. SPECIFIC MICRORNA EXPRESSION PATTERN PREDICTS RECURRENCE IN ATYPICAL MENINGIOMA
Authors: Fadrus Pavel , Tukmachi Dagmar , Duba Milos , Naar Ondrej , Vybihal Vaclav , Sana Jiri , Smrcka Martin , Slaby Ondrej
Published: November 2022

Meningiomas are the most common primary tumors of the central nervous system (CNS). Atypical meningioma (AM) recurs in 40% of patients despite total resection and radiotherapy (RT). No consensus on optimal adjuvant management was found, and it is difficult to identify patients insensitive to RT in real-life clinical practice. A promising group of biomarkers represent microRNAs (miRNAs), short non-coding RNAs that regulate most biological processes, including cell proliferation, differentiation, and apoptosis. The study aims to identify tissue miRNAs capable of predicting patients with AM who could benefit from the indicated adjuvant RT. The study includes 80 patients with AM in the exploratory phase and 400 patients with meningioma in the validation phase. Total RNA enriched with miRNAs was isolated from FFPE tissue using the mirVana miRNA Isolation Kit (TF Scientific). Subsequently, RNA quantity and quality controls were measured using NanoDrop 2000 (TF Scientific) and Qubit 2.0 (TF Scientific) instruments. A global miRNA expression profile was generated using the TaqMan Array Human MicroRNA Cards (TF Scientific), which allow the detection of up to 754 miRNAs simultaneously. Obtained data were processed and integrated through bioinformatics algorithms with clinicopathological data of patients with AM.The study identified significantly dysregulated miRNAs among AM patients with and without recurrence (p < 0.05). Results also suggest dysregulated miRNA expression profile in AM patients with indicated RT who did/did not develop a recurrence (p < 0.05). Lists of individual miRNAs and detailed graphical analyses will be included in the conference presentation.The results will help predict the prognosis of surgically intervened patients more accurately and can help determine which patients will benefit from the adjuvant RT. This research is supported by the AZV grant from the Ministry of Health of the Czech Republic (reg. No. NV19-03-00559) and Conceptual development of research organization (FNBr, 65269705). All rights reserved.
BIOM-59. NOVEL BIOMARKER DISCOVERY AND DIAGNOSTICS FOR INTRA-AXIAL BRAIN TUMORS, USING CSF PROTEOMICS
Authors: Mansouri Alireza , Mikolajewicz Nicholas , Khan Shahbaz , Trifoi Mara , Zacharia Brad , Glantz Michael , Zadeh Gelareh , Kislinger Thomas
Published: November 2022

BACKGROUND

Invasive brain sampling is typically necessary for reliable diagnosis and prognostication of intra-axial brain tumors but carries risk of morbidity. Liquid biopsy of proximal fluids may mitigate this risk. Through direct contact with the tumor microenvironment and, as an ultra-filtrate of plasma, the cerebrospinal fluid may be the ideal matrix. Reflecting the tumor phenotype, proteomic analyses are critical. Here we identified diagnostic CSF proteomic signatures and putatively novel biomarkers for glioblastoma (GBM), brain metastases (BM), and central nervous system lymphoma (CNSL).

METHODS

CSF samples were retrospectively retrieved from the Penn State Neuroscience Biorepository and profiled using shotgun proteomics and the MStern approach. Proteomic signatures were identified using machine learning classifiers and survival analyses.

RESULTS

With as little as 30 µL of CSF, 755 unique proteins were recovered across 73 samples (22 GBM, 17 BM, 14 CNSL, 20 NPH). Proteomic-based classifiers identified malignancy with area under the receiver operating characteristic (AUROC) of 0.94 and distinguished between tumor entities with AUROC ≥0.95. More clinically relevant triplex classifiers, comprised of just 3 proteins, distinguished between tumor entities with AUROC of 0.75-0.89. Novel biomarkers were identified, including GAP43, TFF3 and CACNA2D2, and characterized using single-cell RNA sequencing.

DISCUSSION

Reliable classification of intra-axial malignancies using low CSF volumes is feasible, allowing for longitudinal tumor surveillance. Based on emerging evidence, upfront implantation of CSF reservoirs in brain tumor patients warrants consideration.
BIOM-60. APOLLO: RAMAN-BASED PATHOLOGY OF MALIGNANT GLIOMA
Authors: Lita Adrian , Sjöberg Joel , Filipescu Stefan , Celiku Orieta , Petre Luigia , Gilbert Mark , Noushmehr Houtan , Petre Ion , Larion Mioara
Published: November 2022

Methylation classification is an essential component for integrative diagnosis in glioma, however, the DNA methylation classification is not always available for all the samples. We hypothesized that Raman spectroscopy might be suitable to predict the glioma methylome, based upon its ability to create a molecular fingerprint of the tumor and would provide biological insights into the discriminatory features. Raman Spectroscopy was used for molecular fingerprinting of the regions of interest using 1mm2 FFPE tissue spots from 45 patient samples with LGm1 to LGm6 methylation subtypes. Spectral information was then used to train a convolutional neural network (CNN), capable of detecting the glioma methylation subtypes. 70 % of the dataset was used for model training while the remaining 30% for validation. We demonstrate that Raman spectroscopy can accurately and rapidly classify gliomas according to their methylation subtype from achieved FFPE samples, as a novel way to obtain classification. For each sample we ran Ward linkage clustering with a variable number of clusters (from 2 to 7), with the majority cluster corresponding to tumor spots and the others corresponding to (various types of) non-tumor spots. The average accuracy over all samples was 90:3%, the average precision was 99:6% and the average recall was 90:2%. We show that Raman spectroscopy together with artificial intelligence can predict the methylome of glioma samples and augment the ability to classify these tumors retrospectively. The non-destructive nature of this method and the ability to be applied on FFPE samples directly, allows the histopathologist to reuse of the same slide for subsequent staining and downstream analyses.
BIOM-64. TARGETING IDENTIFICATION OF HOST-BRAIN CANCER SYSTEMIC CYTOKINE SIGNALLING FOR EARLY DETECTION AND TUMOUR SUB-TYPING
Authors: Brennan Paul , Baker Matt
Published: November 2022

Background

The host-tumour interaction is fundamental to brain tumour biology, orchestration of which is mediated in part by cytokines. We reasoned that detection of a tumour-specific cytokine profile in patient serum could contribute to early diagnosis strategies, and permit prediction of tumour subtypes before histological diagnosis.

METHOD

Patient serum blood samples (300ul) were collected prospectively from patients with radiological evidence of a new brain tumour diagnosis pre-treatment, and from symptom-matched patients without radiological evidence of a tumour (controls). Our in-house cytokine assay incorporates antibodies captured onto a nitrocellulose slide. 64 capture antibodies are printed per slide, with 4 replicates per antibody. Fluorescence is measured from a biotin secondary antibody, the signal compared to a standard curve, and the averaged relative intensity across 4 replicates determined. We used a hierarchical clustering strategy to examine the relative expression of all 64 biomarkers for each patient class, and for cancer versus non-cancer. We refined this to identify the most discriminatory biomarkers. We made a univariate examination of the association of each antibody with brain tumour type.

RESULTS

Cytokine profiles were collected from 83 patients (42 glioblastoma, 8 meningioma, 12 metastatic cancer, 6 grade III gliomas, 3 grade II gliomas, 2 other brain tumours, 10 non-cancer patients). The top 4 biomarkers with greatest separation for brain cancer versus non-cancer were osteopontin, MMP3, MMP9 and TIMP-1. A principal component analysis demonstrated clear separation between clusters for these biomarkers. Univariate analysis evidenced discrimination of tumour subtypes, for example MMP9 and oligodendrogliomas.

CONCLUSION

Cytokine signals can be identified in small volumes of patient serum and used to identify brain cancer ‘risk.’ This could support prioritization for brain imaging, and prediction of tumour subtype to guide pre-operative management decision-making. Combination with other liquid biopsy strategies such as serum spectroscopy may improve spectroscopy test performance and utility.
BIOM-65. SAFE MAXIMAL RESECTION OF IDH-WILDTYPE GLIOBLASTOMA WITH TUMOR-FREE MOLECULAR MARGIN RESULTS IN PROLONGED PROGRESSION-FREE SURVIVAL
Authors: Shankar Ganesh , Massaad Elie , Bradley Joseph , Lennerz Jochen , Dietrich Jorg , Choi Bryan , Nahed Brian , Curry William , Batchelor Tracy , Carter Bob , Cahill Daniel
Published: November 2022

Purpose Although maximal resection of wild-type GBM tumors is associated with longer survival, the association of genomic alterations with the ability to resect disease has not been elucidated. This study aimed to determine whether certain molecular alterations are less amenable to surgical resection and whether achieving a surgical margin devoid of tumor cell burden provides a clinical benefit. Methods Molecular profiling of 148 consecutive tumor samples from newly diagnosed patients with IDH-WT GBM SNaPshot genotyping, and methylation-specific PCR for MGMT promoter methylation. The association of alterations with residual volume and progression-free survival was evaluated in regression analyses. We prospectively investigated the impact of TERTp status at the surgical margin on progression-free survival (PFS) in 47 patients. PFS and overall survival (OS) were evaluated with the log-rank test and Cox regression models.Results Overall, 148 patients (91 men [61.5%], median age, 62.5 years [range 56–70 years] had maximally safe surgery. The median follow-up duration was 18 months (IQR, 4-32 months). The rate of PFS was significantly lower in MGMT promoter unmethylated IDH-WT GBM amenable to resection with residual volume >4.9cc (hazard ratio [HR], 2.35; 95% CI, 1.44-3.84; P=.005). Gene amplification (PDGFRA, KIT, KDR) on 4q12 and TP53 and RB1 mutations were associated with greater RV. Prospective trial revealed median PFS for tumors with TERTp mutations in the surgical margin was 10.1 months while tumors with undetectable TERTp mutations in the margin did not progress (median follow-up 8.1 months, IQR 1.6-14.6). Surgical tumor margins devoid of TERTp mutations were associated with significantly different probability of PFS (0.23; 95%CI 0.15-0.43; P< 0.01)Conclusion In conclusion, 4q12 amplification (KDR/PDGFRA/KIT) and tumor suppressor gene alterations (RB1, TP53) were associated with greater residual volume. Tumor-free margins defined spatially by intraoperative navigation as assessed by quantifying TERTp mutation allelic fraction was correlated with prolonged PFS.
BIOS-04. CONTACT: CLINICAL OUTCOME ASSESSMENTS TRENDS IN BRAIN CANCER TRIALS
Authors: Kim Yeonju , Armstrong Terri , Gilbert Mark , Celiku Orieta
Published: November 2022

BACKGROUND

Clinical outcome assessments (COAs) are a key component of patient-centered assessment of net clinical benefit in trials. In neuro-oncology, unique symptoms, treatment-related toxicities, and overall poor prognosis further necessitate a focus on symptom management and quality of life. We conducted a computational survey of trends of COA use in past and ongoing neuro-oncology trials.

METHODS

Neuro-oncology trials on ClinicalTrials.gov were identified using primary malignant CNS tumor terms. Instrument names from PROQOLID (n= 2695) were used to determine COA use. Regression and interrupted time-series analyses assessed chronological and design-related trends.

RESULTS

Among 3584 adult neuro-oncology studies, 20% reported using a specific COA instrument: 21% among (n= 3038) interventional and 16% among (n= 524) observational trials. Among interventional studies, most trials used one instrument (91%) as a secondary outcome (81%). 269 unique COAs were reported overall, most frequently patient-reported (72%) and clinician-reported outcomes (44%) indicated for general neoplasms (59%), all conditions (30%), and brain tumors (21%). Most commonly used instruments among treatment-focused trials (n= 523 reporting COAs) included Performance Status (KPS 18%, ECOG 9%), EORTC QLQ-C30 and QLQ-BN20 (9%), and MMSE (7%). Among supportive care studies (n= 47), HADS (13%), FACT-Br (11%), and KPS (11%) were most frequent. COAs use was more likely in phase 3 versus early phase 1 and phase 1 (OR= 0.12 [(95% CI:) 0.02-0.42]; OR= 0.22 [0.09-0.52]) but not versus phase 2 (OR= 0.60 [0.26-1.36]), and was more likely in supportive care trials (versus diagnostics and prevention: OR= 0.10 [0.01-0.65]; OR= 0.05 [0.00-0.79]). The rate of COA use increased linearly over time (1998-2020; β= 1.1 [0.8–1.4]), with no significant changes surrounding individual regulatory events.

CONCLUSION

A growing proportion of neuro-oncology trials specified COA use, reflecting positive changes toward patient-centered drug evaluation. Further investigation of COA use by phase and trial focus may inform future trial design.
BIOS-05. SANGER SEQUENCING AND COPY-NUMBER ALTERATION ANALYSIS WITH MLPA CAN CLINICALLY CLASSIFY IDH-WILD-TYPE LOWER-GRADE ASTROCYTOMA
Authors: Arakawa Yoshiki , Makino Yasuhide , Yoshioka Ema , Shofuda Tomoko , Kawauchi Takeshi , Terada Yukinori , Tanji Masahiro , Kanematsu Daisuke , Mineharu Yohei , Miyamoto Susumu , Kanemura Yonehiro
Published: November 2022

The IDH-wild-type lower-grade astrocytomas are a heterogeneous entity. According to 2021 WHO classification, IDH-wild-type astrocytomas with any of the following factors show poor prognosis: combination of chromosome 7 gain and 10 loss (+7/-10), and/or EGFR amplification, and/or TERT promoter (TERTp) mutation. Multiplex ligation-dependent probe amplification (MLPA) can detect copy number alterations with a reasonable cost. The purpose of this study was to find precise and cost-effective method for stratifying the prognosis of IDH-wild-type astrocytomas. Sanger sequencing, MLPA, and quantitative methylation-specific PCR were performed for 42 IDH-wild-type lower-grade astrocytomas surgically treated at Kyoto University Hospital, and overall survival was analyzed for 40 patients. Of the 42 IDH-wild-type astrocytomas, 21 were classified as grade 4 in 2021 WHO classification and all of them had either TERTp mutation or EGFR amplification. Kaplan-Meier analysis confirmed the prognostic significance of 2021 WHO Classification, and WHO grade was also prognostic. Cox regression hazard model identified PTEN loss and PDGFRA amplification as independent significant prognostic indicators (Risk ratio of 9.75, p< 0.001 and 13.9, p=0.002). The classification recommended by 2021 WHO Classification could be completed using Sanger sequencing and MLPA. Survival analysis revealed PTEN and PDGFRA were significant prognostic factors for IDH-wild-type lower-grade astrocytomas.
CNSC-08. TUMOUR-INFILTRATED CORTEX PARTICIPATES IN LARGE-SCALE COGNITIVE CIRCUITS
Authors: Mandal Ayan , Assem Moataz , Romero-Garcia Rafael , Coelho Pedro , McDonald Alexa , Woodberry Emma , Morris Robert , Price Stephen , Duncan John , Santarius Thomas , Suckling John , Hart Michael , Erez Yaara
Published: November 2022

In neurosurgery, tumour-infiltrated cortex is generally assumed to be non-functional. While prior studies have suggested integration of tumour-infiltrated tissue in relatively local circuits responsible for language and motor function, it is unknown whether such tissue can participate in distributed networks important for higher-order cognitive abilities like executive function. We tested the hypothesis that diffuse low-grade gliomas integrate into large-scale cognitive circuits using intracranial electrocorticography and resting-state functional magnetic resonance imaging of four patients. To identify brain areas recruited for executive function, electrocorticography recordings were acquired from tumour-infiltrated tissue under three conditions: i) baseline (rest), ii) simple counting (1-20; “easy”), and iii) switch counting (1-a-2-b-3-c etc.; “hard”). In each patient, we observed significant task-based high gamma power modulations in tumour-infiltrated cortex in response to increasing cognitive effort (p < 0.05), implying preserved functionality of neoplastic tissue for complex tasks. Additionally, tumour locations corresponding to task-responsive electrodes exhibited functional connectivity patterns that significantly co-localised with canonical brain networks implicated in higher-order cognitive processing (p < 0.05). Finally, dorsal attention network connectivity in tumour-infiltrated cortex correlated with high gamma power elevations during increased cognitive demand (χ 2(1) = 5.14; p = 0.023), establishing a concordance between both techniques. Overall, this study contributes convergent evidence that tumour-infiltrated cortex can participate in large-scale neurocognitive circuits, prompting a reconsideration of traditional notions of neoplastic brain tissue.
CNSC-10. THE COMPLEX RELATIONSHIP BETWEEN NEURONAL ACTIVITY AND FUNCTIONAL NETWORK PROPERTIES IN GLIOMA PATIENTS
Authors: Zimmermann Mona , Breedt Lucas , Centeno Eduarda , Kulik Shanna , Santos Fernando , Stam Cornelis , van Lingen Marike , Hillebrand Arjan , Douw Linda
Published: November 2022

BACKGROUND

Glioma is associated with pathologically high peritumoral neuronal activity, which associates with faster tumor progression. Concurrently, glioma patients have local and widespread disturbances of the functional brain network as measured with magnetoencephalography (MEG), such as higher network clustering (the extent to which regions connected to a particular area are also connected to each other) and locally altered integrative connectivity (for instance assessed with a centrality measure). How local neuronal activity and nodal network properties relate to each other has yet to be investigated.

METHODS

We obtained eyes-closed resting-state MEG in 95 de novo glioma patients and 57 matched healthy controls (HCs). The offset of the power spectrum was calculated for 210 cortical atlas regions as a proxy for neuronal activity. Regional clustering coefficient (CC) and eigenvector centrality (EC) were calculated in the delta, theta and alpha bands. Offset and network values were then averaged across peritumoral regions, contralateral homologue regions and all non-peritumoral regions. Linear mixed models were used to relate nodal CC and EC to local offset in patients and HCs.

RESULTS

The peritumoral area was significantly more active than the non-peritumoral homologue in patients, and showed pathologically high activity in comparison to HCs. However, patients’ functional network was disturbed globally, showing higher clustering and lower centrality than HCs. Whereas high activity related to high centrality in HCs and patients alike, high activity seemed to relate to low clustering in non-peritumoral regions in patients, but not HCs.

CONCLUSION

We find that the relationship between neuronal activity and functional network properties is disturbed in a complex manner in glioma patients. Our results further underline the importance of investigating how local activity may impact global network topology in order to understand how neuron-glioma interactions shape brain functioning.
CNSC-15. DECIPHERING RAMAN-SPECTRAL TISSUE HETEROGENEITY IN GLIOBLASTOMA
Authors: Klein Karoline , Klamminger Gilbert Georg , Mombaerts Laurent , Jelke Finn , Mirizzi Giulia , Slimani Redouane , Husch Andreas , Mittelbronn Michel , Hertel Frank , Borgmann Felix Kleine
Published: November 2022

Raman Spectroscopy is able to provide a fast identification method for healthy and pathological tissues without the need for sample preparation. This makes it highly interesting for intraoperative use in identifying tumor types and borders. However, the capability of a machine-learning classifier to recognize known tissues based on Raman spectra relies on a solid ground truth that is usually provided by measuring small tissue samples first and analyzing the sample later by histopathology. This approach is limited in very closely interspersed tissues that cannot be identified macroscopically, such as glioblastoma where vital tumor tissue, necrosis and peritumoral tissue with characteristic changes to healthy brain tissue are tightly arranged. These areas have been shown to be distinct in their spectral properties, which makes tumor border identification aided by Raman Spectroscopy challenging. As infiltrative tumors leaving no tumor-cell-free brain tissue, borders need to be defined on a clinical scale, where extensive resection must be weighed against retaining functional brain tissue. For this, spectral analysis beyond tumor identification is necessary. In a computational approach we use methods of unsupervised learning and K-means Clustering to investigate heterogeneity within glioblastomas in the native state in order to reduce the complexity of this tumor type. Thereby, it was possible to extract spectra of necrotic tumor areas and to calculate a prediction probability for necrotic tissue within glioblastomas. Several clusters with spectral similarity to each other could be identified, which might represent the different areas of a glioblastoma. Two of these clusters were identified as probable grey and white matter, respectively, by comparison with autopsy tissue. In addition, this assignment independently confirmed the prediction of the classifier as non-necrotic tissue. Deciphering the spectral heterogeneity of glioblastoma in this way may be a great advantage for the surgeon to identify tumor borders and assist in resection control.
CNSC-18. HYPOXIA-INDUCED METABOLIC ADAPTATIONS THROUGH ACOX-1 IN GLIOBLASTOMA
Authors: Bhattacharya Ayon , Caflisch Laura , Balinda Henriette , Boyer Andrew , Lodi Alessia , Zhou Mei , Li Mengxing , Chiou Jennifer , Pandey Renu , Tiziani Stefano , Vadlamudi Ratna , Brenner Andrew
Published: November 2022

BACKGROUND

Hypoxia is a major driver of invasiveness and resistance in glioblastoma (GBM). We hypothesize that GBM adapts to chronic hypoxic conditions through utilization of peroxisomal fatty acid oxidation (FAO). We explored the contribution of acyl coenzyme A oxidase 1 (ACOX-1), a rate-limiting enzyme for peroxisomal FAO, in metabolic adaptation to hypoxia and as a potential therapeutic target.

METHODS

A primary cell line from a bevacizumab-resistant tumor (012015) was cultured under chronic hypoxia (2%O2) or normoxia (21% O2). We used UPLC-MS/MS and GC-MS to determine lipid and polar metabolites. RNA seq was performed on U251 ACOX-1 (KO) cells under normoxic and hypoxic conditions. Differential gene expression was obtained using TopHat2 (genome alignment), HTSeq, and DEseq. Gene set enrichment analysis was used to compare biological pathways between conditions. ACOX-1 was deleted using CRISPR-Cas9 and orthotopically implanted in NCr/SCID nude mice. Animals were treated with 30 mg/kg of pazopanib or vehicle daily through oral gavage.

RESULTS

In 012015 cells we observed altered carnitine metabolites, increase in specific triglycerides, and S-lactoylglutathione indicating dysfunctional mitochondrial FAO, and increase in oxidative stress between hypoxic and normoxic conditions. Also, decrease in citric acid cycle metabolites, increase in glycolytic metabolites were seen in hypoxia. Further RNA seq on U251 ACOX-1 (KO) cells showed downregulated genes such as PCK1, SCD, SREBF1, PIPOX (p< 1E-8) and significant KEGG pathways such as unsaturated fatty acid (p= 0.009), peroxisome (p= 0.025) and PPAR (p= 0.016) between hypoxia and normoxia suggesting increased dependence of these cells on peroxisomal FAO. ACOX-1 (KO) mice showed increased survival when treated (p= 6.7E-04) with pazopanib.

CONCLUSION

In ACOX-1 (KO) model, we observed metabolomic reprogramming with downregulated genes, dysregulated metabolites, and pathways in peroxisomal FAO in hypoxia. These identified genes could be potential targets for therapy in combination with anti-angiogenic therapies that increase hypoxia in GBM.
SURG-36. EVALUATION OF SURGICAL RESULTS AND PREDICTIVE FACTORS OF HYDROCEPHALUS IN PEDIATRIC PATIENTS WITH POSTERIOR FOSSA TUMORS
Authors: Formentin Cleiton , Matias Leo Gordiano , de Santos Santos Lucas Souza Rodrigues , Joaquim Andrei Fernandes , Tedeschi Helder , Ghizoni Enrico
Published: November 2022

INTRODUCTION

Infratentorial tumors represent 45 to 60% of all brain tumors in children and are associated with hydrocephalus in 70 to 90% of cases. The aim of this study is to describe and analyze the surgical results and correlate them with the incidence of hydrocephalus, as well as identify predictive factors of hydrocephalus in pediatric patients underwent to a surgical treatment of posterior fossa tumors.

METHODS

This is a retrospective observational study, based on demographic, clinical and radiological information of pediatric patients underwent to surgical resection of posterior fossa tumors by a single group between 2011 and 2019.

RESULTS

We included 135 patients with a mean age of 7.56 years, mean follow-up of 35.7 months and overall survival of 18.8 months. Considering the histology, most tumors were pilocytic astrocytomas (34.1%), followed by medulloblastomas (27.4%) Total resection was achieved in 77.8% and tumor recurrence was observed in 16.2%. The rate of hydrocephalus was 36.3%, with most shunt procedures performed preoperatively. There was a high rate of complications associated with shunting (42.9%), mostly represented by infection (71.5%). Patients with hydrocephalus were younger (p = 0.001), showing a faster evolution between the onset of symptoms and diagnosis (p = 0.008). Tumor volume (p = 0.1) and location (p = 0.32) were not statistically significant for hydrocephalus, however, the presence of leptomeningeal disease (p = 0.001) was. The resection rate was also significant, with lesions totally resected showing the best results (p = 0.009). Regarding tumor histology, 33.3% of patients with medulloblastoma and 62.5% of patients with ependymoma were shunted.

CONCLUSION

One third of children with posterior fossa tumors will require a shunt procedure. Some factors should guide the neurosurgeon during patient counseling and surgical planning to minimize the use of permanent shunts and avoid related complications.
SURG-37. NEURO-ONCOLOGICAL AUGMENTED REALITY: A MORE INTUITIVE APPROACH TO RESECTION PLANNING
Authors: Van Gestel Frederick , Frantz Taylor , Neuville Quentin , Klein Sam , Bruneau Michaël , Jansen Bart , Scheerlinck Thierry , Vandemeulebroucke Jef , Duerinck Johnny
Published: November 2022

BACKGROUND

When preparing for the resection of an intracranial lesion, its borders and optimal approach are often determined using neuronavigation with a tracked pointer. This can sometimes prove challenging, especially for deep-seated lesions. Augmented reality (AR) can simplify and improve this step by directly displaying the lesion on the patient's skin.

METHODS

A proprietary inside-out infrared tracking solution was developed, allowing for heads-up displaying AR scenes on the Microsoft HoloLens II without the need for an external tracking camera or computer. We included twenty patients with an intracerebral lesion planned for resection. After semi-automatic hologram-to-patient registration, different participants marked the lesion outlines on the patient’s skin, consecutively aided by the Brainlab neuronavigation system and the HoloLens. Each registration on both systems provided a registration transform that was compared for accuracy and consistency. Participant performance was quantified in terms of duration and accuracy for both patient registration and lesion delineation, and compared to expert performance.

RESULTS

When using AR both registration and delineation were significantly faster than with conventional neuronavigation (p = 0.02 and p < 0.001, respectively, and p < 0.001 for the total duration), taking 79.23 ± 17.48 and 39.58 ± 39.10 seconds while neuronavigation required 96.61 ± 24.54 and 90.80 ± 44.09 seconds. AR had a registration offset of 3.3mm and 3.4°, and was more consistent compared to neuronavigation. AR facilitated more accurate and detailed lesion delineation, while neuronavigation often overestimated lesion size.

CONCLUSION

Augmented reality provides a faster and more accurate alternative for resection planning. Lesion delineation was more intuitive while retaining high accuracy. Future research should focus on further intraoperative implementations.
TMET-01. DISRUPTION OF THE SERINE-PRODUCING PATHWAYS SLOWS PROGRESSION OF THE SONIC HEDGEHOG-DRIVEN MEDULLOBLASTOMA
Authors: Tikunov Andrey , Bates Dale , Macdonald Jeff , Gershon Timothy
Published: November 2022

We have found that medulloblastoma metabolism is specialized to promote growth in the CNS and can be targeted for anti-tumor therapy. Prior studies show that serine is scarce in the CNS and that metastatic tumors require serine-producing enzymes to grow in the brain. We analyzed whether medulloblastoma, a primary brain tumor, showed similar serine dependency. We found that Sonic Hedgehog signaling, which induces proliferation in cerebellar granule neuron progenitors in normal development and medulloblastoma formation when hyperactivated, also induces PHGDH and SHMT1, which each catalyze key steps in different serine-production pathways. To define the functional role of PHGDH and SHMT1 in medulloblastomas, we bred mice genetically engineered to develop SHH medulloblastomas with mice carrying deletions of each of these genes. We found that mice with Phgdh-deleted medulloblastomas showed slower progression and longer survival times, compared to mice with Phgdh-intact medulloblastomas. Medulloblastomas with combined deletion of Phgdh and Shmt1 show even slower tumor progression. Stable-isotope flux analysis suggests that different serine-producing pathways compensate for the loss of individual serine-producing enzymes, providing a rationale for the greater anti-tumor effect of disrupting multiple serine-producing enzymes simultaneously. Our data show that serine-producing enzymes can be targeted as a novel approach to medulloblastoma therapy, and underscore the importance of targeting multiple serine-production pathways in complex metabolic interventions.
CNSC-20. PROTEOMIC ANALYSIS OF GLIOMA BIOPSIES SHOWS CONSISTENCY WITH GLIOMA GRADING
Authors: Leu Severina , Boulay Jean-Louis , le Amer Michè , Ritz Marie-Françoise , Halbeisen Florian Samuel , Schmidt Alexander , Buczak Katarzyna , Hutter Gregor
Published: November 2022

BACKGROUND

Glioma are currently classified according to integrated histopathologic and molecular genetic (WHO 2021 classification) as well as methylomic criteria (Capper 2018). However, little is known about proteomic profiling of these subgroups , which may reveal specific biomarkers and pathways potentially activated or inactivated. Material and

METHODS

Eighty-six glioma biopsy samples were prospectively collected from patients undergoing surgery at the University Hospital of Basel between 2017 and 2019. Samples were classified into seven distinct glioma subgroups based on integrated WHO 2016 and methylome profiling criteria. Proteins were extracted from fresh frozen samples devoid of necrosis/haemorrhage and processed for mass spectrometry analysis.

RESULTS

For each tumour sample, a total of 8’855 proteins were identified and quantified. 950 proteins were differentially expressed between at least two glioma subgroups. Strikingly, most significant differences in expression are related to tumor grading rather than to glioma subgroups. Proteins SSDH and GABT, involved in Gamma-aminobutyric acid (GABA) catabolism, show the strongest increase between low grade glioma (LGG) and high grade glioma (HGG), whereas S10AA and ANXA2, part of pathways involved in coagulation, cell adhesion and immune response, appear increased in HGG.

CONCLUSION

Tumor grading turns out to be dominant over genetic and epigenetic criteria for proteomic classification. Most significant protein level variations may represent potential glioma grade-specific therapeutic targets.
TMET-12. HYPERPOLARIZED Δ- [1-13C] GLUCONOLACTONE IMAGING VISUALIZES TERT-ASSOCIATED CHANGES IN DYNAMIC PENTOSE PHOSPHATE PATHWAY METABOLISM IN GLIOBLASTOMA
Authors: Minami Noriaki , Hong Donghyun , Taglang Celine , Batsios Georgios , Gillepspie Anne Marie , Stevers Nicholas , Viswanath Pavithra , Costello Joseph F , Ronen Sabrina
Published: November 2022

BACKGROUND

TERT promoter mutations are a hallmark of glioblastoma (GBM). We recently reported that the expression of TERT and its upstream transcriptional factor, GABPB1, are strongly correlated with redox in GBM with TERT promoter mutations. However, further imaging biomarkers which visualize redox-associated metabolism and TERT expression are needed. Here we demonstrate that 13C magnetic resonance spectroscopy (MRS) of hyperpolarized δ-[1-13C] gluconolactone metabolism is a useful imaging tool to visualize changes in dynamic pentose phosphate pathway (PPP) metabolism that reflect TERT-associated changes in redox in GBM.

METHODS

U251 human GBM cells stably expressing shRNA targeting TERT or GABPB1 were compared to controls. Doxycyclin-inducible shTERT or shGABPB1 U251 cells were also examined. For in vivo studies, cells were injected into immunodeficient rat brains and tumors confirmed by T2-weighted MRI. δ-[1-13C] gluconolactone was polarized using a Hypersense DNP polarizer and injected into live cells or tumor-bearing rats. For cells 13C-MRS was acquired using a 500MHz Agilent spectrometer and analyzed using Mnova and Matlab software. For in vivo13C-MRS studies, spectra were acquired using a 3T Bruker scanner and a spectral spatial echo-planar spectroscopic imaging sequence. Spectral signal to noise was improved using Tensor denoising. Spectra were processed using a custom-written Matlab script.

RESULTS

Hyperpolarized 6-phosphogluconolactone (6PG), the metabolic product from δ-[1-13C] gluconolactone via the PPP, was significantly reduced in TERT or GABPB1 silenced cells compared to control cells in both U251 models. The positive correlation between TERT expression and 6PG level was confirmed by linear regression analysis. Hyperpolarized 6PG production in both tumor models was also significantly reduced in TERT or GABPB1-silenced tumors compared to controls.

CONCLUSION

We successfully visualized TERT-associated changes in dynamic PPP metabolism in a GBM model in cells and in vivo. Hyperpolarized δ-[1-13C] gluconolactone is a potential tool for monitoring TERT expression in GBM with TERT promoter mutations.
TMET-19. DEFINING A NOVEL ROLE FOR CD97 IN REGULATING GBM GLYCOLYTIC METABOLISM
Authors: Ravn-Boess Niklas , Bhowmick Nainita , Hattori Takamitsu , Prakash Varsha , Stephan Gabriele , Frenster Joshua , Bready Devin , Lawson Christopher , Wilcox Jordan , Placantonakis Dimitris
Published: November 2022

Glioblastoma (GBM) is the most common and aggressive primary brain malignancy. Despite multimodal therapy, disease recurrence is inevitable. To identify novel vulnerabilities of GBM, we performed an arrayed CRISPR/Cas9 screen against select adhesion G protein-coupled receptors (aGPCRs), many of which we found to be de novo expressed in GBM. Knockout of CD97, previously implicated in GBM cell migration, produced the most striking proliferative disadvantage in patient-derived GBM cultures (PDGC) among aGPCRs tested. We found high CD97 surface expression in all our PDGCs, while levels remained nearly undetectable in non-neoplastic brain cells, confirming that CD97 is de novo expressed in GBM. Upon shRNA-mediated knockdown of CD97 in PDGCs from all three TCGA transcriptional subtypes, we observed reduced proliferation, as measured by cell cycle analysis. Notably, CD97 knockdown also significantly reduced tumorsphere formation capacity as measured by limiting dilution assays; an effect that was partially rescued upon CD97 overexpression. To elucidate mechanisms of action of CD97, we performed RNA-sequencing and GO pathway enrichment analysis from PDGCs following CD97 knockdown. The top downregulated pathways involved glycolytic metabolism, specifically involving many genes relevant for glucose-6-phosphate (G6P) and fructose-6-phosphate (F6P) processing. Indeed, when we measured metabolite levels under both steady-state and flux conditions using mass spectrometry, we observed an accumulation of G6P and a depletion of most downstream glycolytic and Krebs cycle metabolites upon CD97 knockdown. Furthermore, Seahorse metabolic assays revealed deficits in both glycolytic metabolism and oxygen consumption. We aim to interrogate the activity of specific glycolytic enzymes involved in processing G6P and F6P, pinpointing how these are influenced by CD97 signaling pathways (MAPK or Akt). Overall; our studies suggest a novel role of CD97 in regulating GBM metabolism (Warburg effect), and provide a strong scientific rationale for developing biologics to target CD97 which appears to be universally and de novo expressed in GBM.
CNSC-22. IDENTIFICATION OF MECHANISMS INVOLVED IN THE RECURRENCE OF GLIOBLASTOMA BY TRANSCRIPTOMIC, PROTEOMIC AND SPATIAL PROFILING ANALYSIS
Authors: Shekarian Tala , Ritz Marie-Françoise , Martins Tomas A , Hogan Sabrina , Schmassmann Philip , Burger Bettina , Hutter Gregor
Published: November 2022

BACKGROUND

Glioblastoma (GBM) is the most aggressive and common brain tumor. Despite multimodal therapy which consists of complete tumor removal, chemo- and radiation therapy in most patients, the tumor recurs, and the overall survival of only 14 months remains very poor. To identify tumor-induced immune evasion and treatment resistance mechanisms induced during GBM recurrence, we aimed at characterizing the immunological/molecular changes in patient-matched treatment-naïve and recurrent GBM samples.

MATERIAL AND METHODS

Proteins and total RNA were extracted from 16 patient-matched treatment-naïve (primary) and recurrent GBM fresh frozen tumor samples. The expression of genes involved in brain immune responses were compared using Nanostring panels encompassing Cancer and Neuroinflammation genes. Proteomic was conducted using 6 patient-matched primary and recurrent tumor samples. Immunostaining was performed on a tissue microarray containing matched primary and recurrent tumor samples to identify tumor cells and microglia in order to assess spatial transcriptome of these specific cell types in situ using GeoMX technology. Moreover, correlation analysis of differentially genes and proteins with time to relapse was performed.

RESULTS

Genes significantly differentially expressed between primary and recurrent tumors revealed genes overexpressed in recurrent tumors belonging to “FCGR-mediated Phagocytosis” and “synapse pruning” pathways. Proteomic confirmed the synaptic signalling considering overexpressed proteins. Correlation studies with the time to relapse indicated that higher expression of FCG receptors, complement molecules and synaptic components correlate with shorter time to relapse, sharing similarities with neurodegenerative/cognitive disorders such as schizophrenia and Alzheimer disease. The source for these molecules is under evaluation with the spatial transcriptomic analysis.

CONCLUSION

Upregulation of specific proteins such as FCG receptors, complement and synaptic components may result in more favourable conditions for tumor regrowth and may therefore be identified as negative predictors patient outcome. Interfering with these molecules may represent novel therapeutic options after initial GBM surgery.
TMET-25. MEK/ERK AND AMPK SIGNALING DICTATE VULNERABILITY TO FATTY ACID DESATURATION INHIBITION IN GLIOBLASTOMA
Authors: Sammarco Alessandro , Eyme Katharina , Jha Roshani , Mnatsakanyan Hayk , Neustadt Rudolph , Moses Charlotte , Alnasser Ahmad , Tardiff Daniel , Su Baolong , Williams Kevin , Bensinger Steven J , Chung Chee Yeun , Badr Christian E
Published: November 2022

Lipid metabolism is altered in many cancers. Glioma stem cells (GSCs), a subpopulation that contributes to molecular heterogeneity and therapeutic resistance of glioblastoma (GBM), are highly dependent on de novo lipid synthesis (DNLS) for energy production and proliferation. Although DNLS is a promising therapeutic target in GBM and other tumors, the molecular mechanisms that determine the dependence on DNLS remain largely unknown. In this study, we aimed to define the genetic drivers of vulnerability to DNLS inhibitors in GSCs and to explore the molecular mechanisms dictating resistance to a brain-penetrant inhibitor of stearoyl-CoA desaturase (SCD), a key enzyme involved in DNLS. Using an astrocyte model of gliomagenesis, we discovered that activation of RAS/MEK/ERK promotes vulnerability to DNLS inhibitors, whereas defective MEK/ERK activity drives resistance to SCD inhibition. Also, we identified the energy sensor AMPK as a downstream target of MEK/ERK and discovered an adaptive metabolic reprograming of GSCs dictated by AMPK activation. Shotgun lipidomics revealed that constitutive AMPK activation protects from SCD inhibition-induced lipotoxicity and endoplasmic reticulum stress and preserves the ability of transformed cells to form brain tumors in mice. Mechanistically, we found that AMPKs ability to circumvent lipotoxicity was achieved by altering the lipid composition and saturation state of cell membranes, and channeling potentially lipotoxic fatty acids into lipid droplets (i.e., lipid storage). These results strongly suggest that the efficacy of DNLS-targeted therapy can be dictated by the MEK/ERK and AMPK signaling status of GSCs. These data also suggest that MEK/ERK and AMPK signaling could be used as predictive biomarkers to understand which GBM patients are likely to respond to DNLS-targeted therapy. In conclusion, our data uncover an unexpected mechanism by which GSCs avoid a metabolic vulnerability and provides a rationale for integrating DNLS-targeted therapies for GBM treatment.