bluuebunny/crossref_metadata_2025 huggingface dataset:
SURG-16. SAMPLING AND PROCESSING OF TUMOR TISSUE DURING RESECTION OF DIFFUSE INTRACRANIAL GLIOMA: INTERNATIONAL SURVEY AND RECOMMENDATIONS FOR STANDARDIZATION ON BEHALF OF FOUR RANO GROUPS
Authors: Karschnia Philipp , Smits Marion , Reifenberger Guido , Rhun Emilie Le , Ellingson Benjamin , Galldiks Norbert , Kim Michelle M , Huse Jason , Schnell Oliver , Harter Patrick , Mohme Malte , von Baumgarten Louisa , Albert Nathalie , Huang Raymond Y , Mehta Minesh , van den Bent Martin , Weller Michael , Vogelbaum Michael A , Chang Susan , Berger Mitchel , Tonn Joerg-Christian
Published: November 2023

BACKGROUND

Surgical resection represents the standard of care for newly diagnosed diffuse gliomas and allows neuropathological evaluation for diagnosis. Moreover, tissue specimens form the basis for research allowing the identification of pathogenetic mechanisms and targets. However, there is no consensus which tumor portions should be systematically sampled to achieve a genuinely representative evaluation in a condition characterized by intratumoral heterogeneity. Guidelines for biospecimen handling and long-term storage are also lacking, limiting comparative analyses between different biobanks.

METHODS

Four international RANO groups from the fields of surgical and medical neuro-oncology, radiation oncology, neuroimaging, and neuropathology aimed to generate a framework for tissue sampling and processing during resection of diffuse glioma.

RESULTS

A core committee of 21 representatives from the four RANO groups identified areas of interest based upon expert consensus and drafted recommendations for best practice guidelines. Those were eventually sent to 38 leading experts in the field for further evaluation using a two-staged eDelphi process, leading to refinement of the recommendations. Only recommendations which were scored as of ‘critical importance’ by ≥ 70% of the expert panelists were accepted. Consensus recommendations were developed for (I) tissue volume and (neuroimaging-based) tumor-specific regions from where the tumor should be sampled; (II) definitions how regions for sampling of non-contrast-enhancing tumor on MRI should be identified; (III) blood and CSF sampling; (IV) handling and storage to enable both neuropathological diagnosis and in-depth research analyses; and (V) the preferred sample labelling to avoid communication errors. These recommendations resulted in a sophisticated intraoperative workflow proposal to accurately depicture the tumor composition during sampling.

CONCLUSION

These RANO recommendations offer a framework to standardize the surgical and post-surgical workflow for prospective biobanking studies which will be presented together with the results of the eDelphi survey at the SNO meeting.
SURG-18. ONCO-FUNCTIONAL OUTCOME AFTER RESECTION FOR ELOQUENT GLIOBLASTOMA (GLIOFO STUDY): A PROPENSITY-SCORED ANALYSIS OF AN INTERNATIONAL, MULTICENTER COHORT STUDY
Authors: Gerritsen Jasper , Mekary Rania , Pisica Dana , Zwarthoed Rosa , Kilgallon John , Nawabi Noah , Jessurun Charissa , Versyck Georges , Pruijn Koen , Fisher Fleur , Larivière Emma , Solie Lien , Kloet Alfred , Tewarie Rishi Nandoe , Schouten Joost , Bos Eelke , Smith Timothy , Dirven Clemens , Broekman Marike , Vincent Arnaud , De Vleeschouwer Steven
Published: November 2023

BACKGROUND

Minimizing residual tumor volume and preventing functional loss are the primary goal in glioblastoma resections in eloquent areas. However, their combined impact on patient outcomes remains poorly understood. We therefore developed a novel onco-functional outcome (OFO) classification and evaluated its benefit in subgroups based on age, preoperative neurological morbidity (NIHSS), and preoperative Karnofsky Performance Score (KPS).

METHODS

Propensity-score matching was used to match OFO 1 (no residual volume, no postoperative functional loss) vs. non-OFO 1 patients for the overall cohort and subgroups based on age, NIHSS, and KPS. Cox proportional-hazard regressions were performed to analyze the association between OFO class and postoperative neurological deficits, KPS deterioration, receipt of adjuvant therapy, overall survival, and progression-free survival. Logistic regressions were performed to analyze the predictive value of perioperative factors on OFO class. Findings Between 2010 and 2020, 858 patients with tumor resection for primary eloquent glioblastoma were included as the overall unmatched cohort. After matching, the overall matched cohort comprised of 512 patients: 256 received OFO 1 and 256 received non-OFO 1. In the overall matched cohort and matched subgroups, OFO 1 resulted in fewer postoperative neurological deficits, lower rates of postoperative KPS deterioration, higher rates of receipt of adjuvant therapy, longer overall survival (median 21.0 months vs. 13.0 months, p < 0.001), and longer progression-free survival (median 10.0 months vs. 7.5 months, p < 0.001). Patients who underwent awake craniotomy more often received OFO 1 (43.0% vs. 26.9%, p < 0.001), and awake craniotomy was an independent predictor for OFO 1 (OR 1.93, p = 0.0070). Interpretation OFO 1 is beneficial in patients with glioblastoma in eloquent areas to improve surgical outcomes, irrespective of age, preoperative NIHSS, or KPS. Furthermore, awake craniotomy was significantly associated with achieving this status. These results might aid neurosurgeons with their surgical decision making in individual patients.
SURG-19. RE-PURPOSING DEEP BRAIN STIMULATORS AS ELECTRIC FIELD THERAPY (EFT) AS TREATMENT FOR GLIOBLASTOMA
Authors: Ma Jun , Dhawan Sanjay , Chen Clark
Published: November 2023

INTRODUCTION

Though alternating electric field therapy (EFT) for glioblastoma received FDA approval, biophysical modeling suggests that field strength generated by scalp electrodes may not sufficiently extend to deep, subcortical regions. Objective: We explore the anti-tumor activity of electric field (EF) generated by electrode directly implanted into glioblastomas, with the goal of repurposing deep brain stimulators as a therapeutic platform. Method: Laboratory characterization and murine modeling Result: In vitro, activation of leads of a deep brain stimulator induced tumoricidal activity within the region encompassed by the EF. To further characterized this tumoricidal activity, a customized two-electrode array was designed and fabricated to allow study of glioblastoma cells seeded at the center of the EF. Consistent with the observations made using the deep brain stimulator electrode, electric field therapy (EFT) induced both necrosis and apoptosis of glioblastoma cells. To characterize this effect in vivo, a four-electrode array was designed and fabricated such that tumor cells can be implanted through a center channel equidistant the electrodes. Mice were implanted with this array, followed by luciferase labelled murine glioblastomas through the center channel. After tumor engravement, mice were randomized to EFT or placebo. EFT was associated with significant diminishment of tumor growth (measured by bio- bioluminescence) and prolonged survival. Analysis of brain sections following EFT showed a notable increase in peri-tumoral microglia accumulation, suggesting potential of EFT as an immune-modulation platform.

CONCLUSION

Our results suggest therapeutic potential for repurposing of deep brain stimulator as glioblastoma therapy, with opportunities for therapeutic enhancement through novel electrode design and stimulation parameter modulation.
SURG-25. SURGICAL MORBIDITY IN RELATION TO THE SURGICAL APPROACH FOR OLFACTORY GROOVE MENINGIOMAS—A POOLED ANALYSIS OF 1016 PATIENTS AND PROPOSAL OF A NEW REPORTING SYSTEM
Authors: Kasper Ekkehard , Mirza Farhan , Kaya Serdar , Walker Robert , Starnoni Daniele , Daniel Roy , Nair Ramesh , Lam Fred
Published: November 2023

BACKGROUND

There is no consensus regarding whether a frontal or lateral approach is superior for resection of olfactory groove meningiomas (OGM). Objective: 1) To compare surgical approaches for microsurgical resection of OGMs for extent of resection and complication rates. 2) To develop a novel preoperative scoring system to guide choice of approach to decrease surgical morbidity.

METHODS

A PRISMA-guided pooled analysis of 20,672 surgical reports on OGMs published in the MRI era using search terms such as ‘olfactory groove meningioma’ and ‘surgery’. After title screening and removal of duplicates, we assessed 871 studies on surgical management of OGMs. Following exclusion criteria, 27 studies were chosen for the final pooled cohort analysis of reported patient outcomes.

RESULTS

The 27 studies identified a total of 1,016 individual patients who underwent open microsurgical resection of OGMs. The approaches used included: pterional/unilateral, bifrontal with variations, and anterior interhemispheric approaches. Across all studies, gross total resection (Simpson Grades I or II) was achieved in 91.4% of cases, and subtotal resection (Grades III and IV) was reported in 8.6% of cases. A cumulative 27% of surgical OGM patients sustained some form of complications. Minor complications 22.2% (CSF leak, seizures, infection, transient cranial nerve palsies, hydrocephalus). Major complications 4.7% (hemorrhage, ischemic infarct, malignant cerebral edema). Correlation between complications and the surgical approach was performed. Among 426 patients who underwent unilateral approaches, 14% experienced minor complications, and 2.1% experienced major complications. The 410 patients who underwent bifrontal approaches, 24.6% experienced minor complications, and 7% experienced major complications.

CONCLUSIONS

Unilateral approaches appear to have lower complication rates than bilateral approaches, however, the extent of resection is not uniformly reported, making it difficult to identify differences. We herein propose a novel preoperative imaging-based classification scoring system to help select the most suitable surgical approach to achieve lower post-surgical complication rates.
SURG-27. 17-YEAR EXPERIENCE OF SURGICAL MANAGEMENT OF INTRADURAL EXTRAMEDULLARY (IDEM) TUMORS: CLINICAL OUTCOMES FROM A LOW- AND MIDDLE-INCOME COUNTRY
Authors: Ozair Ahmad , Suresh Vinay , Suresh H S , Raju Bharath , Ahluwalia Manmeet
Published: November 2023

INTRODUCTION

Surgical outcomes of intradural extramedullary (IDEM) tumors have been well-reported in the literature from high-income countries. However, limited contemporaneous data from low- and middle-income countries (LMICs) exists. This study sought to analyze the clinical outcomes of all IDEM tumor cases operated during a 17-year period at a resource-limited setting in an LMIC.

METHODS

The present work was conducted and reported in accordance with Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines. A retrospective cohort study was carried out to analyze all IDEM tumor cases, operated upon by a consultant neurosurgeon, during 2004-2021, at a resource-limited setting in Southern India. All patients underwent routine biochemical and radiological investigations, including contrast-enhanced MRI. Laminectomy and tumor resection under the microscope were done without using intraoperative neuro-monitoring. Nerve fibers running through the tumor were sacrificed. Bilateral facet joints were preserved to ensure integrity without spinal fusion. All cases received a dural closure with 5-0 Prolene, with postoperative MRI confirming complete resection. Patients received telephonic and/or in-person follow-up visits.

RESULTS

50 patients with a mean age of 46.3 years (range 13-80) were included, with 31 males and 19 females. Their clinical presentation included radiculopathy (78%), radiculomyelopathy (12%), and radiculomyelopathy with bowel and bladder symptoms (10%). Histologically, schwannomas were the most common (52%), followed by neurofibromas (34%), meningiomas (12%), and ependymomas (2%). Two individuals were diagnosed with Neurofibromatosis Type 1. All meningiomas occurred in the thoracic region, with 83.3% of cases being in females. All patients had symptomatic relief postoperatively. No major adverse events occurred, including CSF leaks, permanent neurological deficits, or spinal instability. Recurrence occurred in two 'dumbbell' tumors (4%) at 5 and 7 years after primary excision during follow-up, managed with successful re-resection.

CONCLUSION

Microsurgical excision of IDEM tumors carries high safety and efficacy, including in resource-limited settings like LMICs.
SURG-28. MULTI-STAGE, OPEN CRANIAL APPROACHES FOR RESECTION OF PRIMARY INTRACRANIAL NEOPLASMS: A SYSTEMATIC REVIEW OF THE HISTORY AND CURRENT APPLICATIONS
Authors: Bui Nicholas , Brown Nolan , Kuo Cathleen , Gendreau Julian , Abraham Mickey
Published: November 2023

Staged surgery for skull base lesions has been utilized to facilitate maximal safe resection and optimize outcomes while minimizing morbidity and complications. Conversely, staged surgery for primary intraparenchymal neoplasms is less commonly performed and has not been reported as extensively within the literature. As such, we performed a systematic review to examine the unique surgical indications for staging, timing between stages, specific surgical approaches utilized, and postoperative complications of staged surgery for primary intra-axial neoplasms. METHODS: A literature search was conducted in August 2021 using PubMed, Web of Science, and Cochrane databases using the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) recommendations. Titles and abstracts were evaluated independently by 2 authors, after which articles were selected for final analysis based on application of strict inclusion criteria during full text screen. Each included article was then qualitatively assessed and relevant variables—including operative approaches, timing, and outcomes—were extracted for synthesis. RESULTS: Of 115 results, 7 articles were included for final analysis and consisted of 17 pediatric and 4 adult patients. Staged approaches were more commonly utilized in the pediatric patient population for resection of astrocytoma and glioma. Pediatric patients had a timing of surgeries ranging from 5–10 days between operations, compared with 18 days to 4 months in adult patients. Complications in pediatric patients were most commonly hemiparesis, hydrocephalus, cranial nerve VI and VII palsies, truncal ataxia, and cerebellar mutism, while complications in adult patients included language and abstract thinking deficits, respiratory failure, and motor weakness. CONCLUSION: This study reports the first comprehensive review of staged surgical procedures for primary, intra-axial cranial neoplasms. There exists a large degree of heterogeneity in complications resulting from staged surgeries for intra-axial neoplasms, which are similar to complications associated with single-stage surgery for intraparenchymal lesions as well as multi-stage surgeries for skull base lesions.
SURG-31. DEFINING THE NEW POSSIBILITIES FOR CESIUM BRACHYTHERAPY IN PATIENTS WITH PERIVENTRICULAR GBM
Authors: Ablyazova Faina , Sharma Anurag , Huang Lyu , Wang Lin , Ben-Shalom Netanel , Ellis Jason , D'Amico Randy , Boockvar John , Potters Louis , Wernicke A Gabriella
Published: November 2023

INTRODUCTION

Re-irradiation of patients with external beam radiotherapy (EBRT) for recurrent glioblastoma (GBM) continues to present a therapeutic dilemma due to a high risk of radiation induced necrosis (RN). In contrast, brachytherapy represents a safer, more conformal radiation option aimed at optimizing local control while minimizing the risk of brain tissue damage. Immediate intra-operative implantation with brachytherapy prevents tumor repopulation and offers patients two procedures in one setting. However, due to the risk of seed migration, surgical resection and brachytherapy in periventricular regions was deemed unachievable. In heavily pretreated periventricular GBM, where further EBRT is complicated by RN, a barrier between the ventricular lining and tumor cavity is needed to prevent seed migration. We present two patients where such a barrier allowed successful implantation of brachytherapy to improve disease control.

METHODS

Two patients, previously treated with surgery and EBRT, presented with recurrent GBM abutting the ventricles. Following GTR of the tumors, a barrier was created by patching the ventricle with Gelfoam to prevent seed migration. Intraoperative brachytherapy implantation of suture stranded Cs-131 seeds (Isoray) for patient 1 and collagen embedded Cs-131 (GammaTile) for patient 2 was performed. A total of 20 Cs-131 seeds on strings threaded through Surgicel, and 6 GammaTiles (24 Cs-131 seeds), were used implanted in patients 1 and 2, respectively. Surgicel covered the implanted seeds and the resection cavity filled with Adherus.

RESULTS

Post-operative CT scan demonstrated all 20 Cs-131 seeds and 24 Cs-131 seeds in the surgical cavities of patients 1 and 2, respectively, and had serial post operative imaging with MRI scans showing Cs-131 seeds layering surgical cavity, as late as 6 months in total follow up. To date, both patients have had durable local control and no seed migration.
SURG-36. CLINICO-RADIOLOGICAL PARAMETERS, MOLECULAR AND CHROMOSOMAL ALTERATIONS AFFECTING SURGICAL OUTCOME OF PETROCLIVAL MENINGIOMAS
Authors: Suri Ashish , Suri Vaishali
Published: November 2023

Petroclival meningiomas were reviewed for correlation of extent of resection with clinico-radiological parameters and molecular/chromosomal alterations. 53 surgical procedures in 50 patients of petroclival meningioma were performed. Cavernous sinus and sellar extension were present in 37(69.8%) and 5(9.4%) respectively; contralateral extension in 10(20%). Modified anterior transpetrous rhomboid-MATRA (44=83.0%) was the most commonly used approach, followed by retrosigmoid (2=3.8%), and combined (7=13.2%) approaches. Hypointense tumors on T2-weighted MRI (OR:5.85;95%CI:1.70-20.41) and presence of brainstem edema (OR:4.53;95%CI:1.36-15.12) were found to be significant factors increasing the likelihood of subtotal resection-STR (p = 0.004 & p = 0.011 respectively). In the presence of both tumor T2-hypointensity and brainstem edema, there was significant increase in the likelihood of STR (p = 0.001;OR:25;95%CI:3.52-177.48). The most common cranial nerve to suffer new-onset deficit postoperatively was found to be VI nerve(19=35.8%) followed by V(9=16.9%) and VII(8=15.8%) nerves. On long-term follow-up, 38 patients had good outcome. Out of the 16 cases for which molecular analysis was performed, no specimen was found to have pTERT-C228T,C250T, AKT-1, E17K and SMO-L412F,W535L mutations. Eight (50.0%) cases showed H3K27me3 loss while 5 (31.25%) had hemizygous CDKN2A deletion. All(100%) patients harboring H3K27me3 loss and/or hemizygous CDKN2A deletion had cavernous sinus extension compared to 62.5% patients without H3K27me3 loss and 72.7% with hemizygous CDKN2A retention. Similarly, hemizygous CDKN2A deletion and H3K27me3 loss are associated with increase in the rate of brainstem edema from 27.3% to 60% and 25% to 50% respectively. Cases (n = 4) with both these alterations have 100% cavernous sinus extension and 75% chances of brainstem edema and lack of arachnoid plane. The MATRA is a versatile approach for petroclival meningiomas with good surgical outcome and acceptable complication rates. T2 hypointense tumor and brainstem edema on pre-operative imaging are significant predictors of STR. H3K27me3 loss and hemizygous CDKN2A deletion may be associated with cavernous sinus extension suggesting their role in tumor spread.
SURG-42. FACTORS INFLUENCING TUMOR RECURRENCE AFTER RESECTION OF SKULL-BASE MENINGIOMAS
Authors: Begley Sabrina , McBriar Josh , Park Jung , Dehdashti Amir
Published: November 2023

BACKGROUND

Resection of skull-base meningiomas is challenging, given the proximity of and adherence to neurovascular structures. We characterize the benefits of neurosurgical resection of meningiomas, comparing clinical and surgical outcomes based upon tumor location within and outside the skull base.

METHODS

Data were retrospectively collected from 85 patients who underwent surgical resection of meningioma between 2008 – 2018, for whom long-term follow-up was available. Outcomes were compared between locations: non-skull base, anterior fossa, middle fossa, and posterior fossa. Logistic regression analysis was used to analyze pre-operative and pathologic factors influencing recurrence.

RESULTS

Forty-five (54.1%) tumors were located on the skull base: 29 anterior fossa, 22 middle, and 6 posterior. Simpson grade 1 or 2 resection was achieved in 63 patients. Mean Ki-67 showed a statically significant difference between all tumor locations: non-skull base (7.1), anterior fossa (4.0), middle fossa (10.8), posterior fossa (2.8) (p = 0.009). Simpson grade differed significantly by tumor location with percentage of Simpson grade 1 resections as follows: non-skull base supratentorial (45.7%), non-skull base infratentorial (0.0%), anterior (71.5%), middle (30.0%), posterior (16.7%) (p = 0.022). Tumors recurred in 11 patients with recurrence differing significantly between locations: non-skull base (18.2%), anterior (3.8%), middle (36.4%), posterior (0.0%) (p = 0.046). Median progression-free survival was 115.5 months and did not significantly differ by location. Larger tumor volumes (p = 0.018), Simpson grade 3 resection (p = 0.016), and increased Ki67 (p = 0.046) were associated with higher recurrence risk. No variables predicted post-operative neurological deficits.

CONCLUSIONS

High variability exists within skull-base meningiomas, depending on the cranial fossa of origin. Location may impact the molecular make-up, extent of resection, and patient outcomes. Due to the high-risk anatomy of the skull base, confirming these predictors of recurrence is vital to optimize initial treatment and decrease the risk associated with salvage treatment.
SURG-45. THE EFFECT OF STAPEDECTOMY IN POSTOPERATIVE OUTCOME OF SUPERIOR SEMICIRCULAR CANAL DEHISCENCE: A CASE SERIES OF 349 REPAIRS
Authors: Torres Lisette , Vohra Sanah , Mekonnen Mahlet , Pandey Aryan , Chow Ariana , Gopen Quinton , Yang Isaac
Published: November 2023

INTRODUCTION

Superior Semicircular Canal Dehiscence (SSCD) is a pathology of the otic capsule, in which, a “third mobile window” is formed on the osseous labyrinth surrounding the superior semicircular canal. Otosclerosis, another otic capsule pathology, can occur concurrently, therefore obscuring the symptoms seen in patients with SSCD. It is currently unknown whether the surgical procedures to treat otosclerosis such as stapedectomy can affect symptom resolution in patients following SSCD repair. Objective: To examine the association between post-SSCD repair symptom resolution and history of stapedectomy.

METHODS

A single institution retrospective review was conducted to evaluate post-operative symptom resolution in patients undergoing SSCD repair from 2011-2021. 349 SSCD repairs performed in a cohort of 279 patients were included, and among those were 10 patients with a history of stapedectomy. A p-value < 0.05 was considered statistically significant.

RESULTS

A total of 349 surgical repairs were analyzed. The patient population was composed of 63% female and 37% male with patient ages’ ranging from 13-84 years. Patients were divided into two different cohorts based on their history of stapedectomy. We compared these cohorts looking at their post-SSCD repair symptom changes and found no statistically significant differences between patients with and without history of stapedectomy. We also compared pre- and post-operative symptoms amongst the 10 patients with a history of stapedectomy and found no statistically significant differences in symptom resolution post-SSCD repair. Post-operative symptoms analyzed included amplification (p = 0.2), aural fullness (p = 0.2), autophony (p = 0.8), disequilibrium/imbalance (p = 0.8), dizziness (p = 0.3), headache (p = 0.7), hearing loss (p = 1), hyperacusis (p = 1), tinnitus (p = 0.4), and vertigo (p = 0.3).

CONCLUSIONS

With respect to symptom resolution post-SSCD repair, there were no significant differences between patients with and without a history of stapedectomy. Hence, previous stapedectomy surgery should not be considered an adverse condition to SSCD repair, with similar rates of improvement after SSCD surgery.
TMET-04. SENSITIZING DIPGS TO ANTIFOLATES: A PRECLINICAL STUDY ON PURINE BIOSYNTHESIS TARGETS
Authors: Mersich Ian , Congrove Sunny , Dasgupta Biplab
Published: November 2023

Diffuse Intrinsic Pontine Gliomas (DIPGs), among the most devastating pediatric brain tumors, present a desperate need for innovative treatment strategies, given the lack of effective therapies. Our study unveils a significant metabolic vulnerability in DIPGs, rooted in purine biosynthesis, a key facilitator of tumor progression. Contrary to prior reports, we demonstrate DIPG cell lines' sensitivity to methotrexate, an antifolate that targets purine metabolism, underscoring a potential reappraisal of its therapeutic role. Further, our research reveals a promising therapeutic synergy between antifolates, namely methotrexate and LSN-3213128, and SHMT inhibition, offering a potential novel treatment combination. This synergy, demonstrated in a proof-of-concept study, curtailed tumor progression in our DIPG mouse model, underscoring a promising new treatment strategy. Importantly, we identify a paradoxical antifolate resistance mechanism: while typical resistance is linked to dysfunctional folate transport, our findings intriguingly show an upregulation of folate transporters and intracellular folate in DIPGs. This paradox suggests that elevated intracellular folate levels may be effectively outcompeting antifolate metabolites for their targets. Significantly, the failure of physiological concentrations of purines in the cerebrospinal fluid (CSF) to restore DIPG cell viability under antifolate treatment further reinforces our rationale for targeting purine metabolism. The resistance mechanism is further validated by the observed synergy with SHMT inhibition, which disrupts the folate cycle allowing for the antifolates to out-compete the intracellular folates for their intended target. Our findings challenge conventional wisdom, open new avenues in DIPG therapeutic strategy, and highlight a paradoxical antifolate resistance mechanism that necessitates further exploration in the field.
TMET-10. INVESTIGATING HOW GLIOBLASTOMA TUMOUR CELLS EXPLOIT THEIR METABOLIC MICROENVIRONMENT
Authors: Shard Chloe , Ormsby Rebecca , Poonnoose Santosh , Toubia John , Trim Paul , Ebert Lisa , Patil Ashwini , Gomez Guillermo
Published: November 2023

A significant challenge in neuro-oncology is identifying the metabolic fuel sources that underpin glioblastoma malignancy. Metabolic reprogramming is a hallmark of tumorigenesis, providing malignant cells with an adaptation advantage to survive and grow under environmental stresses, including anti-cancer therapies. Incorporating single-cell RNA sequencing data from 56 glioblastoma patient biopsies, we have identified distinct subpopulations of malignant cells which diverge in their metabolic activities. These metabolic subpopulations are conserved across patient datasets but vary in abundance from patient to patient, contributing to glioblastoma heterogeneity. We are also employing spatial transcriptomics to build a map of the metabolic tumour landscape. This analysis showed that these malignant sub-populations occupy distinct spatial regions in the tumour landscape. Environmental influences like distance to blood vessels, which impact oxygen and nutrient supply, can vary significantly between regions. This suggests that as malignant cells colonise different regions of the tumour, they modify their metabolism as an adaption response. Importantly these niches vary in their compositions of native brain and immune cells, contributing to the diverse ecosystems inhabited by these malignant subpopulations. The next steps are to explore the specific metabolite dependencies of these tumour cells by mass spectrometry imaging and identify metabolite fluxes within the microenvironment that we can target therapeutically.
TMET-13. DNA DAMAGE SIGNALING ACTIVATES GTP SYNTHESIS TO PROMOTE GLIOBLASTOMA TREATMENT RESISTANCE
Authors: Scott Andrew J , O'Brien Alexandra , Zhou Weihua , Xu Jie , Palavalasa Sravya , Kothari Ayesha , Wilder-Romans Kari , Lin Angelica , Zhao Zitong , Yang Annabel , Korimerla Navyateja , Peterson Erik , Yang John , Zhang Li , Andren Anthony , Chandrasekaran Sriram , Venneti Sriram , Heth Jason , Umemura Yoshie , Qi Nathan , Woulfe John , Morgan Meredith , Lawrence Theodore , Al-Holou Wajd , Lyssiotis Costas , Wahl Daniel
Published: November 2023

Glioblastoma (GBM) is the most common type of invasive brain tumor in adults and is uniformly fatal due to inherent resistance to radiation therapy (RT) and chemotherapy. Our group and others have found that metabolites can regulate DNA repair and therapy resistance in brain tumors, but little is known about how DNA damage regulates metabolic pathway activity in cancer. Here we show that following treatment with RT, GBMs increase rates of de novo guanylate synthesis in vitro and in orthotopic patient-derived xenograft models via signaling through the DNA repair protein DNA-PK. To determine if disrupting this regulation can augment GBM treatment efficacy, we combined an FDA-approved inhibitor of purine synthesis (mycophenolate mofetil, MMF) with chemoradiation in a variety of mouse models of GBM. Critically, targeting GTP synthesis improved the efficacy of both RT alone and chemoradiation in multiple patient-derived and syngeneic intracranial models. Our translational studies have shown that mycophenolic acid, the active metabolite of MMF, penetrates the blood-brain barrier at concentrations sufficient to inhibit GTP synthesis in GBMs of human patients. The phase 1 arms of our study, which are ongoing, are testing the safety and efficacy of combining MMF with standard of care chemoradiation for patients with primary and recurrent GBM.
TMET-18. METABOLOMIC APPROACH TO IDENTIFICATION OF PROGNOSTIC BIOMARKERS OF GLIOBLASTOMA
Authors: Aboubechara John Paul , Liu Yin Allison , Fiehn Oliver , Fragoso Ruben , Lee Han , Riess Jonathan , Hodeify Rawad , Bloch Orin , Aboud Orwa
Published: November 2023

Glioblastoma, the most common malignant primary brain tumor, is associated with poor prognosis despite aggressive treatment. Alterations in cellular metabolism driven by acquired mutations contribute to tumor progression and recurrence. Metabolic changes in plasma can serve as potential biomarkers, offering insights into treatment response and prognostic value. In this prospective study, we enrolled 36 patients with isocitrate dehydrogenase (IDH) wild type glioblastoma (18 MGMT methylated, 16 MGMT unmethylated, 2 MGMT unknown) and performed untargeted metabolomics on patient plasma before and after surgery, as well as before and after concurrent chemoradiation. Our analysis focused on examining changes in 157 metabolites throughout each stage of treatment. We conducted correlations between metabolite levels and treatment stages, as well as associations between metabolite levels and disease progression or overall survival to identify clinically relevant biomarkers. Preliminary results demonstrate positive correlation between specific metabolite levels at the time of diagnosis and eventual overall survival. Notably, metabolites such as trans-4-hydroxyproline, ribose, pipecolinic acid, phenol, kynurenine, inositol-4-monophosphate, indole-3-propionic acid, glucose, arachidonic acid, 5-methoxytryptamine, and 3-aminopiperidine-2,6-dione show significant positive correlations (p< 0.05) with overall survival. However, no metabolites exhibited negative associations with overall survival. Ongoing analysis will further explore the relationship between metabolite levels at different treatment stages and survival outcomes. By future planned machine learning techniques integration to our study, we aim to enhance our understanding of the metabolomic changes associated with treatment response and prognosis. This study represents a step toward unraveling the metabolomic alterations in glioblastoma patients throughout treatment. Although the underlying metabolic pathways and potential shared mechanisms are not yet fully understood, the identified metabolites associated with overall survival hold promise as potential biomarkers for prognosis. Furthermore, the integration of machine learning techniques will provide a more comprehensive understanding of the complex metabolic changes in glioblastoma.
TMIC-04. IMMUNE PROFILING OF PEDIATRIC ONCOHISTONE GLIOMAS REVEALS DIVERSE MYELOID POPULATIONS AND TUMOR-PROMOTING BEHAVIORS
Authors: Andrade Augusto Faria , Topouza Danai , McNicholas Michael , Gonzalez Santiago Eduardo G , De Cola Antonella , Gehlhaar Arne , Jessa Selin , Chandarana Bhavyaa , Russo Caterina , Faury Damien , Danieau Geoffroy , Zeinieh Michele , Krug Brian , Wei Yuhong , Wu Qing , Nakada Emily M , Juretic Nikoleta , Larouche Valerie , Weil Alexander G , Dudley Roy , Karamchandani Jason , Agnihotri Sameer , Ellezam Benjamin , Quail Daniela , Konnikova Yelizaveta , Kleinman Claudia , Walsh Logan , Pathania Manav , Jabado Nada
Published: November 2023

Pediatric high-grade gliomas pHGG are lethal and frequently bear missense mutations in histone H3, which drive tumorigenesis by altering the epigenome and cell fate/differentiation. While previous studies showed intrinsic contingencies associated with tumor development, limited information exists on the tumor microenvironment (TME) and immune cells for these tumors. To define the immune landscape of pediatric tumors at single-cell resolution, we profiled and compared 69 pediatric gliomas samples using the Chromium 10X technologies, H3.3 K27M (N=19) and G34R (N=16) mutant tumors, low-grade gliomas (N=11) and ependymomas (N=23). Additionally, to enable the spatial resolution of immune lineages, we performed Imaging Mass Cytometry (IMC) on H3-mutant samples (H3.3 K27M (N=7) and G34R (N=5)). We demonstrate that pediatric histone H3-mutant gliomas are highly infiltrated by myeloid cells, more specifically resident microglia, bone-marrow derived macrophages (BMDM) and monocytes, and are devoid of lymphoid infiltration. Different myeloid subsets were found to interact with H3-mutant cancer cells. Classical BMDM showed strong interactions with H3-mutant cancer cells while monocytes subsets showed tendency to interact only with G34R cells. We have generated a novel H3.3K27M glioma immunocompetent murine model, establishing a highly-penetrant and reliable tool. H3.3K27M murine tumors recapitulated the TME from human tumors, showing great myeloid infiltration. Using in vivo orthotopic serial engraftments, we observed that secondaries transplanted tumors had a significantly worse survival, possessing a less diverse immune infiltration compared to initial engraftments and a dominant presence of myeloid cells. Interestingly, in vivo myeloid depletion combined with PD-1 blockade extended overall mice survival. Our findings provide a valuable characterization of the biology of these tumors, reinforcing the several roles of myeloid cells in the context of pediatric brain tumours, providing a framework for understanding the H3.3K27M and G34R tumors, including other pediatric gliomas, and designing future immunotherapies.
TMIC-05. UNVEILING THE IMPACT OF PTN-PTPRZ1 SIGNALING ON GLIOBLASTOMA PROGRESSION THROUGH TUMOR MICROENVIRONMENT COMMUNICATION
Authors: Ge Weihong , Kan Ryan , Fazzari Elisa , Azizad Daria , Ito Joyce , Yilgor Can , Tse Christopher , Tum Andrew , Patel Kunal , Nathanson David , Bhaduri Aparna
Published: November 2023

Glioblastoma (GBM) is the most lethal primary brain tumor with high rate of recurrence. GBM’s high inter- and intra-heterogeneity present a huge challenge to both disease modeling and treatment. Recent progress in the field has highlighted the role of signals associated with the microenvironment factor in driving tumor progression, suggesting that more detailed characterizations of the GBM microenvironment may provide novel therapeutic targets. In this study, we used a novel stem cell derived cortical organoid transplantation model, where we transplanted patient IDH wild type GBM cells onto organoids and provided multiple culture conditions to explore the impact of the environment on tumor cell identity. After several weeks of culture, single cell RNA-sequencing of tumor and non-neoplastic organoid cells was used to profile molecular features, demonstrating not only cellular composition of GBM and its surrounding normal brain cell, but also the bidirectional communication between the two. We observed functional heterogeneity where individual tumors responded differently to environmental perturbations. However, the most significant cell-cell interaction between tumors and the microenvironment was found to be PTN-PTPRZ1, which is well-maintained across all transplantation models we tested, as well as in re-analysis of published patient data that included tumor and normal cells. Encouraged by our previous works as well as others, which have revealed PTPRZ1 as an outer radial glia marker gene driving tumor invasion, we further verified PTN/PTPRZ1 expression not only in our organoid transplantation models but also on FFPE sections from GBM patients and mouse xenograft samples. These data suggest that this signaling axis promotes tumor progression through tumor – microenvironmental crosstalk, and using the organoid model we show a functional role for this communication. Together, this study presents a GBM organoid transplantation modeling system, which we leverage to detect a promising therapeutically target existing between GBM and its microenvironment.
TMIC-06. GLIOBLASTOMA PROGRESSION IS PROMOTED BY C5AR1 SIGNALING THROUGH EMT INDUCTION, AND ITS BLOCKADE BY W54011 ATTENUATES MALIGNANT PHENOTYPES
Authors: Yoo Jihwan , Oh Yoojung , Lee Dongkyu , Choi Seonah , Kim Eui-Hyun , Moon Ju Hyung , Chang Jong Hee , Kang Seok-Gu
Published: November 2023

BACKGROUND

Glioblastoma multiforme (GBM) is an aggressive brain tumor with poor prognosis. Tumor mesenchymal stem-like cells (tMSLCs) in GBM tissues secrete complement component 5a (C5a), which promotes tumor malignancy. This study aimed to investigate the impact of C5a on GBM tumorspheres (GBM-TS) and to evaluate the therapeutic potential of C5a inhibition using the C5a antagonist, W54011.

METHODS

RNA sequencing (RNAseq) was performed on tumor tissues to identify differentiaaly expressing genes (DEG) and perform gene set enrichment analysia (GSEA) to correlate with patient survival based on C5aR1 expression. GBM-TS and tMSLCs were cultured to create a conditioned medium (CM) containing C5a, which was used to stimulate GBM-TS. The effect of C5a on GBM-TS proliferation, invasion, and stemness was determined using WST/ATP assay, 3D invasion assay, and neurosphere formation assay. Western blot and RNAseq analysis were performed to validate the results. In vivo studies were conducted using orthotopic xenograft mouse models injected with GBM-TS alone or with CM and treated with W54011.

RESULTS

Patients with high C5aR1 expression had a poor prognosis. Treatment with CM increased proliferation, invasion, and stemness of GBM-TS, but W54011 reversed these effects. Treatment with CM induced epithelial-messenchymal transition (EMT) in GBM TSs, whereas W54011 restored the spherical morphology and induced apoptosis. Our results were supported by transcriptome analysis and marker expression in Western blots. In the orthotopic xenograft mouse model, co-injection of GBM-TS and CM resulted in larger tumors and poorer survival, while treatment with W54011 reduced tumor size.

CONCLUSIONS

C5a promotes the growth, invasion, and stemness of GBM-TS, and inhibition of C5a using W54011 may have therapeutic potential for patients with high C5a expression. These results provide insight into the underlying mechanisms of GBM progression and establish a knowledge base for the clinical efficacy of W54011 in GBM treatment.
TMIC-08. CLAUDIN-1 UPREGULATION IN GLIOBLASTOMA INDUCED BLOOD-BRAIN-BARRIER DYSFUNCTION VIA A PARACRINE MECHANISM
Authors: Schweiger Brittany , Kievit Forrest
Published: November 2023

BACKGROUND

Blood-brain-barrier (BBB) disruption is a well-known phenomenon in glioblastoma. However, the mechanism driving BBB dysfunction in GBM is still unknown, especially in the previously established vasculature near the invasive edge. In this study, we aimed to determine if GBM paracrine signaling is sufficient to induce BBB dysfunction and identify changes in the tight junctions of the BBB.

METHODS

An in vivo xenograft model was established through an intracranial injection of U-87 MG cells in nude mice. Weekly MRIs were performed to monitor tumor growth. Two weeks after tumor appearance, brains were collected following a 4% PFA perfusion for immunostaining and confocal imaging. An in vitro model of the BBB was created by seeding primary mouse brain microvascular endothelial cells (BMECs) on transwell inserts. Once the BMECs reached confluency with a TEER value of 170-175Ω*cm2, the media was replaced with filtered conditioned media from U-87 MG cell line, an IDH mutant cell line, or BMECs for three days with TEER values monitored each day.

RESULTS

Immunofluorescent staining revealed a significant increase in claudin-1 expression and decrease in claudin-5 expression in the tumor vs normal brain tissue of our in vivo model (p < 0.01). After 24 hours of exposure to conditioned media from both U-87 MG and IDH mutant cells, BMECs had a significant decrease in TEER compared to control and BMEC conditioned media (p < .0001). After 72 hours, TEER values continued to decrease, reaching around 155Ω*cm2, with control BMECs remaining around 187Ω*cm2.

CONCLUSIONS

These results suggest GBM cells secrete factors capable of inducing changes in the tight junction proteins of the BBB and increasing its permeability. Future studies will aim to identify the mechanism in which these changes occur.
TMIC-09. PRIMARY CILIA REGULATE EXTRACELLULAR VESICLE-MEDIATED IMMUNOSUPPRESSION IN HUMAN GLIOBLASTOMA CELLS
Authors: Jung Mi-Yeon , Trichka Josie , Oishi Masahiro , Agyeman-Andoh Afua , Welsh Joshua , George Jubin , Roehrkasse Amanda , Laws Maxwell , Jones Jennifer , Adoro Stanley , Parney Ian , Brown Desmond
Published: November 2023

Glioblastoma is the most common primary malignant brain tumor. Despite maximal safe resection, followed by chemoradiation, median survival is 15 months, and 5-year survival is 6.8%. Efficacy of immunotherapy is limited by glioblastoma-mediated immunosuppression. Extracellular vesicles (EVs) are a heterogeneous group of small membrane-bound particles that are released from all cell types. Glioblastoma-derived EVs regulate the tumor microenvironment and tumor progression in a paracrine manner. They also regulate glioblastoma-mediated systemic immunosuppression in an IL6- and PDL1-dependent manner by inducing myeloid-derived suppressor cells (MDSCs) ultimately resulting in T cell depletion. Primary cilia are ubiquitous microtubule-based organelles that project from the mother centriole and are present on glioblastoma cells. Inhibition of ciliogenesis–through knockdown of KIF3A, IFT88, or ARL13B (structural ciliary proteins required for ciliogenesis)–abolishes IL6 induction in response to chemoradiation and significantly reduces the induction of MDSCs in normal human donor monocytes exposed to glioblastoma-derived EVs. Inhibition of ciliogenesis does not affect the biophysical properties of EVs but our data instead suggest significant alterations in EV packaging and content in response to ciliary loss. These data suggest a novel role for primary cilia in packaging of EV contents and connects these organelles with tumor EV-mediated immunosuppression in glioblastomas. These findings have potential implications for improving the efficacy of immunotherapy in glioblastoma–a universally fatal disease.
TMIC-11. SPATIAL PROFILING OF TUMOR VASCULATURE AT AUTOPSY IN BRAINSTEM GLIOMAS
Authors: Straehla Joelle , Woods Jared , Vogelzang Jayne , Jones Jacquelyn , Ligon Keith , Alexandrescu Sanda
Published: November 2023

BACKGROUND

Diffuse midline glioma (DMG) is a lethal pediatric tumor, and new treatment strategies are urgently needed. To design therapies that can cross the blood-tumor barrier, we designed a pilot study to investigate protein expression on DMG tumor vasculature using spatial profiling, with attention to targetable surface proteins.

METHODS

We identified 5 patients and 4 controls consented to institutional tissue banking protocols with adequate autopsy tissue from multiple anatomical regions within the brainstem. Portions of formalin-fixed, paraffin-embedded tissue were arranged into tissue microarrays profiled using the nanoString GeoMX platform. Briefly, a multiplexed cocktail of 51 primary antibodies tagged with UV-photocleavable oligonucleotide barcodes and fluorescent morphology markers were applied to tissues and 10-14 regions of interest (ROIs) were segmented by vessel area for each patient. ROIs were processed using UV light and barcodes were quantified using ex situ digital counting.

RESULTS

Five patients were included in the pilot study with average age 9.8 years (range 8-13), and overall survival was 9.5 months (range 3-18 months). Three tumors were classified as DMG, H3K27-mutant, WHO grade 4; one as high grade glioma without identified histone alteration but with recurrent DMG drivers (ACVR1 and PIK3CA mutations) and one as infiltrating atypical glioma with high proliferative rate and no DMG driver mutations. Controls ranged from 4-15 years and did not have pathological changes in the brain at death. Protein abundance was compared between cases and control and within cases where tumor-adjacent normal tissue was identified. Several proteins were significantly more abundant on tumor vasculature compared to non-tumor adjacent or control brainstem vessels. Validation studies in primary tissue are ongoing.

CONCLUSIONS

Digital spatial profiling is a promising technology for investigating tumor vasculature and is feasible in autopsy specimens. Work is ongoing to validate candidate biomarkers and expand the cohort to develop a vascular atlas for DMG.
TMIC-13. EXHAUSTED CD8+ T CELLS MAINTAIN LOW-GRADE GLIOMAS IN NF1-MUTANT MICE
Authors: Barakat Rasha , Chatterjee Jit , Mu Rui , Qi Xuanhe , Cobb Olivia , Gao Karen , Gu Xingxing , Smirnov Igor , Kipnis Jonathan , Gutmann David
Published: November 2023

T cells are minor cellular constituents of the brain tumor microenvironment, but have recently been shown to play critical roles in glioma pathobiology and treatment. Previous studies from our laboratory have shown that T cells are required for the formation and growth of low-grade gliomas (LGGs) in murine models of the Neurofibromatosis type 1 (NF1) tumor predisposition syndrome. To better characterize the immune landscape of these pediatric low-grade tumors, we leveraged single cell RNA sequencing of human pediatric pilocytic astrocytomas and genetically engineered mouse LGG (Nf1-optic glioma) models. First, we showed that both human and murine LGGs contain a CD8+ T cell population expressing PD-1 and TIGIT, similar to conventional exhausted T cell populations. Second, these PD-1+/TIGIT+ CD8+ T cells are actively recruited to the tumor site by Ccl2 where they dictate tumorigenesis through the elaboration of Ccl4, a cytokine necessary for microglia Ccl5-mediated support of Nf1-OPG growth. As such, Ccl4 expression was enriched in PD-1+/TIGIT+ CD8+ T cells relative to all other T cell populations within these tumors. Third, this “exhausted” CD8+ T cell population was exclusively present in the optic nerves, but not in the blood, dura, or deep cervical nodes of optic glioma-bearing mice. Fourth, targeting this PD1+/TIGIT+ exhausted CD8+ T cell population with immune checkpoint monoclonal antibody inhibitors reduced CD8+ T cell tumoral recruitment, Ccl4 production, and optic glioma growth. Collectively, these findings establish an obligate role for PD-1+/TIGIT+ CD8+ T cells in Nf1-optic glioma control and suggest that immune checkpoint modulation may be useful for the treatment of LGGs in children.