bluuebunny/crossref_metadata_2025 huggingface dataset:
EPCO-28. UNVEILING INVASIVE MECHANISMS OF GLIOBLASTOMA CELLS THROUGH MULTIMODAL SINGLE-CELL SEQUENCING
Authors: Wu Yiyan , Wu Benson , Ellenbogen Yosef , Mansouri Sheila , Kant Joan , Li Xuyao , Singh Olivia , Habibi Parnian , Kossinna Pathum , Rodriguez Sandra Ruth Lau , Gao Andrew , Zadeh Gelareh , Gaiti Federico
Published: November 2024

Glioblastoma (GBM) is the most common malignancy of the central nervous system, characterized by a dismal prognosis and inevitable recurrence despite aggressive standard-of-care therapy. Extensive colonization of the surrounding brain parenchyma precludes complete surgical resection, posing a significant therapeutic challenge. While well-studied in model systems, the molecular features and epigenetic regulators of invasive GBM cells remain under-explored directly in clinical samples. To address this gap, we performed a multimodal single-cell sequencing characterization of GBM tumor samples from anatomically distinct regions collected using MRI guidance. Our results demonstrate an enrichment of progenitor-like (neural- and oligodendrocyte-like) malignant states and neurons at the tumor margins. In contrast, differentiated-like states and myeloid cells were more abundant in the tumor core. Peri-tumoral progenitor-like malignant states expressed a unique neuronal signature associated with synaptic signaling, neurogenesis, and Notch signaling. Further, the expression of this neuronal signature was correlated with increased invasiveness. Analysis of matched primary-recurrent GBM patient cohorts revealed an expansion of this neuronal activity program, which was associated with worse overall survival. Motifs of proneural transcription factors implicated in neuronal lineage differentiation were also found to be differentially accessible in progenitor-like malignant states marked by the neuronal invasive signature, potentially contributing to the remodeling of cell states at the invasive margin. Further, cell-cell interaction analysis predicted greater communication between neurons and peri-tumoral progenitor-like malignant states, mediated predominantly through neurexin-neuroligin trans-synaptic signaling, facilitating synaptogenesis and the integration of tumor cells into neural circuits. Altogether, these findings suggest a model in which GBM invasive cells communicate with normal brain neurons in peri-tumoral regions, exploiting neurodevelopmental pathways to facilitate invasion and potentially seed recurrence. Our characterization of invasive GBM cells provides insight into the mechanisms of brain invasion and highlights potential therapeutic vulnerabilities of malignant invasive cells. Understanding these mechanisms opens new avenues for targeted therapies aimed at curtailing the invasive and adaptive capabilities of GBM.
EPCO-32. PROSPECTIVE GERMLINE SEQUENCING OF PATIENTS WITH GLIOMAS, GLIONEURONAL OR NEURONAL TUMORS
Authors: Lin Andrew , Nandakumar Subhiksha , Mehine Miika , Kemel Yelena , Mandelker Diana , Karajannis Matthias , Sait Sameer Farouk , Gavrilovic Igor , Pentsova Elena , Schaff Lauren , Stone Jacqueline , Nolan Craig , Boire Adrienne , Grommes Christian , Santomasso Bianca , Diamond Eli , Wilcox Jessica , Piotrowski Anna , Kaley Thomas , Young Robert , Imber Brandon , Brennan Cameron , Moss Nelson , Tabar Viviane , Rosenblum Marc , Bale Tejus , DeAngelis Lisa , Mellinghoff Ingo , Berger Michael , Stadler Zsofia , Schultz Nicholas
Published: November 2024

BACKGROUND

Several genetic syndromes have been linked to the development of central nervous system (CNS) tumors; however, the prevalence and clinical significance of germline pathogenic variants in this population remain unclear.

METHODS

2,367 patients with a glioma, glioneuronal, or neuronal tumor (WHO grade 1-4) ages 0.2-93.8 years underwent tumor and matched normal sequencing with MSK-IMPACT. Germline variants and copy-number variants affecting 90 well-established cancer predisposing genes were analyzed; the presence of biallelic inactivation was determined using FACETS.

RESULTS

Eleven percent harbored germline pathogenic mutations in high-, moderate-, and low-penetrance genes. High- and moderate-penetrance genes included CHEK2 (n=32, 1.3%), BRCA2 (n=10; 0.4%), TP53 (n=9; 0.4%), NF1 (n=6; 0.2%), and mismatch repair (MMR) genes (n=20, 0.9%). Low-penetrance genes included monoallelic MUTYH (n=42; 1.8%) and the APC I1307K variant (n=28, 1.2%). Biallelic inactivation was found in all tumors from patients with germline TP53 and NF1 mutations, with lower rates in tumors from patients with a germline MMR alteration (53%). Biallelic inactivation was rare among patients with a germline mutation in homologous recombination pathway (HRD) genes (27%), and in the aforementioned low-penetrance APC (15.3%) and MUTYH (10.2%) variants. All patients with biallelic inactivation of an MMR gene were hypermutated. Biallelic inactivation of MMR genes and TP53 were observed in IDH-mutant astrocytoma and IDH-WT gliomas, while biallelic inactivation of NF1 and somatic IDH1/2 mutation were mutually exclusive. When examining the age at diagnosis among patients with germline alterations, tumors with biallelic inactivation were diagnosed at a younger age compared to tumors with monoallelic alterations (37.7 vs 51.6 years, p=0.002).

CONCLUSION

Clinical germline sequencing identifies a germline mutation in a high proportion of patients with CNS tumors. Biallelic inactivation was most commonly identified in tumors from patients with germline TP53 or NF1 mutations and were less common in patients with a germline MMR alteration.
EPCO-39. MULTIOMIC AND CLINICAL ANALYSIS OF MULTIPLY RECURRENT MENINGIOMAS REVEALS RISK FACTORS, UNDERLYING BIOLOGY, AND INSIGHTS INTO EVOLUTION
Authors: Pugazenthi Sangami , Patel Bhuvic , English Collin , McGeehan Kyle , McCornack Colin , Mok David , Anzaldua-Campos Markus , Nouri Shervin Hosseingholi , Yano Hiroko , Klisch Tiemo , Harmanci Akdes , Patel Akash , Kim Albert
Published: November 2024

Although meningiomas, the most common primary brain tumor, are often effectively treated with surgery and radiation, an important subset of meningiomas behave aggressively and are characterized by treatment resistance and multiple recurrences. Prior work has yet to specifically study multiply recurrent meningiomas (MRMs), including whether they are molecularly distinct from non-recurrent meningiomas (NRMs) at initial diagnosis and whether the molecular features of MRMs evolve with subsequent recurrences. The objective of this study was to identify clinical and molecular features associated with MRMs and determine if longitudinal molecular changes occur in paired MRM samples. In this dual institution study, clinical parameters were collected for 1,186 meningioma patients. After propensity score matching, 31 MRMs were matched to 84 NRMs. Molecular sequencing including whole exome sequencing (n=44), EPIC bead chip methylation array (n=43), and RNA-sequencing (n=66) were performed. On multivariable binomial logistic regression, MRMs were significantly associated with male sex (P=0.012), subtotal resection (P=0.001), higher number of meningiomas on presentation (P=0.017), and histopathological sheeting (P=0.002). Multiomic analysis of primary meningiomas revealed MRMs exhibit greater global copy number alternations (CNA) (P=0.0113) and increased DNA methylation (P=0.0161). Integrated methylation profiling and RNA-sequencing identified candidate driver genes of MRMs. Among these genes, we demonstrate that knockdown of EDNRB, a locus with higher promoter methylation and decreased gene expression in MRMs, leads to increased meningioma cell proliferation, suggesting a tumor suppressor function. CNAs, subclonal evolution, and methylation profiles of MRMs did not significantly change from primary tumor to recurrence, even after radiation treatment, suggesting MRMs are molecularly aggressive from initial diagnosis. Overall, we identify several novel clinical and molecular risk factors associated with MRMs. MRMs harbor unique molecular features on presentation, which do not appear to change during evolution and after treatments, which has implications for development of biomarkers and therapeutic agents for these aggressive tumors.
EPCO-46. SPATIAL TRANSCRIPTOMICS ANALYSIS OF GLIOBLASTOMA REVEALS THREE DISTINCT REGIONAL PROGRAMS OF T-CELL INFILTRATION
Authors: Wang William L , Chen Yiyun , Mo Chiu Ho , Good Zinaida , Sotillo Elena , Mackall Crystal L
Published: November 2024

Glioblastoma (GBM) resists T-cell killing by developing an immunosuppressive tumor microenvironment. Transcriptomic technologies, such as single-cell RNA sequencing (scRNA-seq), have characterized immune cell phenotypes and putative cell-cell interactions in GBM. However, the tumor microenvironment surrounding T-cells is still not well characterized, motivating the need for spatial analyses. Two publicly-available GBM spatial transcriptomic datasets were analyzed, with one discovery cohort (N=18) and one validation cohort (N=12). Using cell deconvolution with a scRNA-seq reference dataset, areas of high T-cell infiltration were identified and clustered into regional programs based on transcriptomic signatures. To highlight which ligand-receptor interactions are most prominent in these regional programs, a novel spatial enrichment algorithm was applied. The impact of spatially enriched ligand-receptor interactions on overall survival was evaluated using bulk RNA-sequencing data from The Cancer Genome Atlas (TCGA). Three distinct T-cell regional programs (transitional, immunosuppressive, and infiltrative) were found across both the discovery and validation cohort. The infiltrative T-cell regional program resided on the periphery of the tumor with a neural progenitor phenotype (NRGN, VSNL1, SLC17A7). In contrast, the immunosuppressive T-cell region had a higher proportion of malignant cells and a greater mesenchymal tumor signature (ANXA1, CD44, complement pathway). Furthermore, ligand-receptor enrichment analysis showed that the immunosuppressive region had higher tumor and tumor-associated macrophage (TAM) signaling towards CD4 T-cells along the collagen, midkine, and osteopontin pathways. TCGA survival analysis showed that higher collagen and midkine signals were associated with worse overall and disease free survival. Our results identified three distinct regional programs in GBM and highlight a set of signaling pathways associated with T-cell suppression. Our findings suggest that the disruption of these pathways could reduce immunosuppressive signals from tumor and TAMs to T-cells. Subsequent validation with spatial proteomics data in glioblastoma is ongoing.
EPCO-52. INVESTIGATING EGFR CONTAINING EXTRACHROMOSOMAL DNA DYNAMICS IN GBM
Authors: Zhao Bo , Cho Chae Yun , Ye Lingqun , Akdemir Kadir
Published: November 2024

The epidermal growth factor receptor (EGFR) is the most frequently altered gene in GBM, with EGFR amplification occurring in approximately 40% of all glioblastomas, half of which exhibit the EGFRvIII deletion variant. EGFR amplification often occurs through the formation of extrachromosomal DNA (ecDNA), where EGFR typically co-amplifies with upstream enhancers. ecDNA is commonly found in a wide range of cancer types, particularly Glioblastoma (GBM), but is rare in normal cells. The uneven segregation of ecDNAs results in oncogene copy number variations in subclones, producing highly heterogeneous tumor cells and providing a selective advantage to cancer cells in response to changing environmental conditions. Meanwhile, ecDNAs keep evolving through fusion, deletion, or integration of new fragments, resulting in alterations to their structure and sequence. Some ecDNAs can reintegrate into chromosomal DNA, disrupting the integrity of chromosomal genes or rewiring chromosomal gene expression via ecDNA resident enhancers. However, the dynamics of EGFR-containing ecDNA (ecEGFR) have not been thoroughly investigated across primary and recurrent GBM. In this study, we profiled 47 glioblastoma specimens (both primary and recurrent) using a multi-omic approach, including WGS, RNA-seq, and ATAC-seq, identifying ecDNA in 14 samples, 10 of which carried EGFR. EGFR deletions were observed in 4 ecEGFR-positive samples, with 2 being the vIII variant. Interestingly, EGFR deletions predominantly occurred in the primary GBM. These ecEGFR samples exhibited significantly high EGFR copy number, gene expression, and chromatin accessibility. Additionally, there were samples with ecEGFR in the primary tumor but not in the recurrent tumor, or ecEGFR appears only in recurrent tumor. One patient showed an ecEGFR deletion in the primary tumor, while the recurrent tumor exhibited wild type ecEGFR.
EPCO-56. INHERITED PREDISPOSITION TO ADULT GLIOMAS: OVERVIEW OF THE CURRENT CLINICAL PRACTICE AND FUTURE RECOMMENDATIONS
Authors: Patel Saumya , Balay Lara , Maga Tara , Maraka Stefania
Published: November 2024

Gliomas are the most common adult primary malignant brain tumor and occur in ages 45-65 years old. While most gliomas are sporadic in nature, a small portion is related to cancer predisposition syndromes (CPS), such as Li Fraumeni or Lynch syndromes. Given that 5–10% of patients will have a family history of glioma, there is currently an effort in identifying germline variants associated with gliomas. Additionally, with the advent of somatic tumor testing, it is possible to pick up suspected germline mutations in genes that cause CPS. Our experience includes a 32-year-old patient diagnosed with astrocytoma IDH mutant, Grade 2 who was found to have a BRAC1 mutation on somatic brain tumor testing. 10 years later, the patient was found with metastatic ovarian cancer and a germline BRAC1 mutation. Early identification of CPS can lead to early detection or prevention of malignancies in affected patients and relatives. However, gliomas are rarely the primary or presenting tumor of CPS, and guidance of CPS screening for these individuals is still lacking. Due to the increasing interest and importance of CPS testing in patients with glioma we have developed a collaborative protocol between our neuro-oncologists and genetic counselors aso that patients have access to germline testing. We propose that all patients with glioma at age of 50 or under, patients with strong family history of cancer including gliomas, and patients with suspected germline mutations based on tumoral somatic mutational profile should be referred to the genetic counselors. Our preliminary findings include 8 patients who completed germline genetic testing. Of these, one patient tested positive for a BRCA1 pathogenic variant. We are planning to continue to collect this data to better inform clinical practice.
EPCO-57. INTEGRATED ANALYSIS OF BULK AND SINGLE-CELL RNA SEQUENCING DATA OF PRIMARY AND METASTATIC PEDIATRIC MEDULLOBLASTOMA
Authors: Orozco Ana Isabel Castillo , Danieau Geoffroy , Khazaei Niusha , Aghababazadeh Masoumeh , Khatami Marjan , Garzia Livia
Published: November 2024

Medulloblastoma (MB) is a highly aggressive and the most common brain tumor in childhood. MB presents a high intertumoral heterogeneity, with at least four molecular subgroups identified (SHH, WNT, Group 3, and Group 4). Metastatic MB, or Leptomeningeal Disease (LMD), is predominantly found in the MB Group 3 type. Although LMD represents a main clinical challenge, its molecular mechanisms remain poorly characterized. Recent research has shown that primary and MB metastasis diverge dramatically. Our work has focused on establishing therapy naïve Group 3 Patient-Derived Xenografts models of primary and metastatic Medulloblastoma to conduct transcriptomic profiling at the bulk and single-nuclei RNAseq levels to identify genetic drivers/pathways that sustain leptomeningeal disease compartment. Our results show various signaling pathways enriched across LMD models, such as MYC targets, unfolded protein response, and fatty acid metabolism. Using single-sample GSEA analysis (ssGSEA) and deconvolution approaches, we have also identified that our PDXes models retain neoplastic subpopulations previously identified in MB single-cell sequencing studies. Similarly, we have identified slight differences in cell subpopulation proportions between primary and leptomeningeal compartments. Our single-nuclei studies have confirmed these results and differentially expressed genes previously found in bulk RNAseq analyses. These results suggest the presence of cell populations enriched in the metastatic compartment with an aberrant transcription phenotype and adaptations in fatty acid metabolism to survive the leptomeningeal space. In conclusion, our work supports the notion that primary and LMD retain subpopulation clusters present in MB Group 3 tumors with different proportions in the metastatic compartment shown by bulkRNAseq deconvolution and single nuclei RNA analysis. We also show that primary and LMD are transcriptionally different, with various enriched pathways in the metastatic compartment and shared among LMD Group 3 PDX models. Through these approaches, we aim to elucidate the genetic dependencies of metastatic Medulloblastoma that will help for targeted therapies.
ANGI-07. A CASE OF HYPERBARIC OXYGEN USED AS A TREATMENT MODALITY FOR ANAPLASTIC ASTROCYTOMA
Authors: Boldig Catherine , Jaffer Muhammad , Pina Yolanda , Mokhtari Sepideh
Published: November 2024

Although its precise mechanism is unclear, hyperbaric oxygen is thought to impede the growth of tumor cells by inhibiting tumor hypoxia, a known driver for angiogenesis. We present a case of a 32-year-old pilot who developed sudden onset aphasia and disorientation which led to hospitalization and imaging. He was diagnosed with anaplastic astrocytoma and underwent resection, radiation, and chemotherapy with temozolomide. Approximately one year later, MRI showed enlarging non-enhancing T2/FLAIR hyperintense mass in the right temporal lobe. He received 4 cycles of lomustine. Four months later, MRI showed slight increase in the size of ring enhancement around the treatment area. These findings were thought to be related to treatment-related changes. After 4 doses of bevacizumab every 2 weeks, there was improvement in surrounding vasogenic edema. However, after 7 doses, his MRI brain demonstrated increase in treatment-related changes with more vasogenic edema. He also had worsening left-sided weakness, unable to lift his left arm against gravity, dysarthria, and cognitive slowing. MRI perfusion supported treatment-related changes rather than tumor growth. He then started hyperbaric oxygen treatments and after 20 sessions of treatment, his vasogenic edema and his left-sided weakness improved. After 60 sessions of hyperbaric oxygen, he noticed further improvement in his strength and short-term memory. Four months after completion of his hyperbaric oxygen, he was found to have increasing size of ring-enhancing lesion and was restarted on hyperbaric oxygen treatments in addition to bevacizumab and low-dose temozolomide. He completed a total of 100 rounds of hyperbaric treatments. MRI showed improvement and stability. His left-sided weakness continued to improve. Hyperbaric oxygen alone or combined with other treatment modalities may be a promising therapy to improve quality of life. Further research will assist with mechanisms through which hyperbaric oxygen works and patient outcomes.
ANGI-08. SPATIAL TRANSCRIPTOMIC COMPARISONS OF GLIOBLASTOMA TISSUE REVEAL UPREGULATION OF NEURODEVELOPMENTAL PATHWAYS AND SYNAPTIC GENES IN INFILTRATING TUMOR CELLS
Authors: Harwood Dylan , Pedersen Vilde , Bager Nicolai , Schmidt Ane , Stannius Tobias , Areškevičiūtė Aušrinė , Josefsen Knud , Nørøxe Dorte , Scheie David , Rostalski Hannah , Lü Maya , Locallo Alessio , Lassen Ulrik , Bagger Frederik , Weischenfeldt Joachim , Heiland Dieter , Vitting-Seerup Kristoffer , Michaelsen Signe , Kristensen Bjarne
Published: November 2024

Glioblastoma remains one of the deadliest brain malignancies. First-line therapy consists of maximal surgical tumor resection, chemotherapy, and radiotherapy. Malignant cells escape surgical resection by migrating into the surrounding healthy brain tissue, where they give rise to the recurrent tumor. Gene expression profiling allows glioblastoma tumor cores to be classified into mesenchymal, proneural, and classical subtypes, each with distinct genetic alterations and cellular compositions. In contrast, the adjacent brain parenchyma where infiltrating malignant cells escape surgical resection is less characterized in patients. Using single-cell and multicellular resolution spatial transcriptomics on tissues from both the tumor core and infiltrated brain tissue (n = 11), we compared the transcriptional profiles of malignant cells in these regions. Malignant cells near regions with microvascular proliferation showed increased expression of genes related to vascular homeostasis. Within tumor cores, proneural and mesenchymal subtypes exhibited distinct spatial gene expression patterns, although these differences were reduced in the infiltrated brain tissue, apart from gene expression due to chromosomal alterations specific to the proneural subtype. We identified two transcriptional patterns of brain infiltration, with the dominant pattern showing a transition from mesenchymal to proneural states. This transition was accompanied by increased expression of genes linked to neurodevelopmental pathways and glial cell differentiation. Additionally, one gene module upregulated in infiltrating malignant cells was predictive of poor patient survival and enriched for genes associated with differentiated neuronal cells. Together, our findings provide an updated view of the spatial landscape of glioblastomas and infiltrated brain tissue, furthering our understanding of the malignant cells that invade healthy brain. This insight offers new avenues for targeted therapy after surgical resection of the primary tumor.
ANGI-10. NETWORK ANALYSIS ESTABLISHES CSF2RA’S REGIONAL INFLUENCE ON HYPOXIA RESPONSE IN THE INVASIVE RIM OF HIGH GRADE GLIOMA
Authors: Flick Matthew , Stevens Victoria , Sereduk Christopher , Plaisier Christopher , Barajas Ramon , Hu Leland , Kannan Kasthuri , Tran Nhan
Published: November 2024

BACKGROUND

High-grade glioma (HGG) is the most common and aggressive form of primary brain cancer. Standard of care surgery employs Magnetic Resonance Imaging to identify the contrast enhancing (CE) core for resection, leaving a non-enhancing (NE) invasive rim of tumor which contributes to recurrence. The hypoxic tumor microenvironment is thought to drive invasion into healthy brain, and understanding cellular responses to hypoxia may provide insight into combatting recurrence. Here, we apply a graph network to integrate regionally heterogeneous data from a unique dataset of spatially-localized CE and NE biopsies from a large cohort of patients with HGG to identify gene networks regulating hypoxia response and invasion.

METHODS

RNA-sequencing of 1159 differentially expressed genes across 159 IDH-wt biopsies (74 patients) from NE/CE regions were represented as nodes in a Neo4j graph network. Candidate genes for network random walks occurred exclusively within NE communities detected by modularity optimization and were localized by cell-type using single-cell RNA-sequencing (scRNAseq). CSF2RA was selected as source (walk length = 5; 10,000 walks/source node). Frequently occurring genes (one-tailed test) in walks were ranked by correlation with CSF2RA expression in NE samples and analyzed by gene set enrichment analysis for biological processes (clusterProfiler). CSF2RA and hypoxia gene expression were visualized with DoHeatmap in composite NE/CE scRNAseq profiles.

RESULTS

CSF2RA, an immune receptor, was upregulated (logFC = 0.789) in NE samples, scRNAseq myeloid populations, and Glycolytic/Plurimetabolic glioma subtype. CSF2RA random walk genes (n=46) enriched metabolic/proliferative signatures. CSF2RA expression correlated negatively with hypoxia genes globally and regionally (NE/CE), while NE/CE scRNAseq revealed distinct cellular expression patterns of CSF2RA and hypoxia response genes.

CONCLUSION

CSF2RA expression may prime NE glioma cells for invasion by altering hypoxia response. The genetic network bridging CSF2RA and hypoxia response may be a targetable mechanism of tumor recurrence.
ANGI-12. THE IMPACT OF STANDARD-OF-CARE TREATMENT ON THE RELATIONSHIP BETWEEN CELL DENSITY AND SOX2 POSITIVITY IN GLIOBLASTOMA PATIENTS AT AUTOPSY
Authors: Bobholz Samuel , Lowman Allison , Aaronsen Daniel , Winiarz Aleksandra , Dueweg Savannah , Flatley Michael , Nath Biprojit , Kyereme Fitzgerald , Connelly Jennifer , Mrachek Kelly , Krucoff Max , Banerjee Anjishnu , LaViolette Peter
Published: November 2024

INTRODUCTION

Sex-determining region Y-box 2 (SOX2) staining highlights pluripotent cells and provides an early sign of tumor cell invasion in glioblastoma patients. This infiltration can often occur at the single cell level and can occur in the absence of lower resolution histological tumor features such as hypercellularity. This study assessed the impact of standard treatment regimens on the relationship between cellularity and SOX2+% at death using autopsy samples as ground truth.

METHODS

A total of 36 IDH-wildtype glioblastoma patients were included for this study (23M/13F, mean age=61.9). Tissue samples from both suspected tumor invasion and suspected normal tissue were collected for each patient, which were then stained for SOX2, digitized at 40X resolution, and segmented into positive staining nuclei percentage using a color deconvolution algorithm. These samples were then aligned to the MRI using in-house MATLAB-based software, where manually defined control points placed on areas of architectural similarity are used to compute a transform that corrects for nonlinear shrinkage of the tissue sample due to post-mortem processing. The association between SOX2+% and cell density was then computed per subject, and compared between patients who received SOC (radiation and temozolomide) treatment following surgery (as well as additional treatment per case, n=31) and patients who opted for no additional treatment following surgery (n=5).

RESULTS

Patients who received no additional treatment showed substantially higher correlation between cell density and SOX2+% than patients who had received SOC (t=2.90, p=0.006). No association with overall survival was observed (r=0.17, p=0.329).

CONCLUSIONS

These results indicate a decoupling between hypercellularity and SOX2+% associated with standard GBM treatments, indicating that radiation and other treatments induce a more heterogenous tumor microenvironment that could lead to single-cell tumor invasion beyond gross histological markers of tumor presence.
ANGI-14. DRUGGABLE GENOME CRISPR SCREEN IN 3D HYDROGEL DEVICES REVEALS TARGETABLE KINASES AND PHOSPHATASES IMPLICATED IN CYTOSKELETAL REORGANIZATION IN INVADING GBM CELLS
Authors: Hu Mufeng , Weldy Anna , Akins Erin , Jain Saket , Chang Alexander , Kumar Sanjay , Aghi Manish
Published: November 2024

The invasive nature of glioblastoma cells into adjacent brain tissues is a key factor in its unfavorable prognosis. To decipher the mechanisms driving glioblastoma invasion, we developed microdissectable biomimetic 3D hydrogel invasion devices containing hyaluronic acid hydrogels decorated with integrin-binding peptides (RGD) and crosslinked with protease-cleavable crosslinkers. The ability to disassemble these devices and interrogate cells in the core vs. invasive fraction allows for high throughput screens. We thus performed a screen in GBM43 cells expressing CRISPR/Cas9 and a 13,250 gRNA library targeting the 2550 genes in the druggable human genome. Of seven initial hits from this screen, only two could be validated by single gene CRISPR and use of a drug to target the hit - ACP1 (also known as LMW-PTP) and Aurora Kinase B (AURKB). Integration of ChIP-seq and RNA-seq revealed no plausible transcriptional targets of ACP1 and AURKB that could drive invasion. Proximity labeling with the TurboID system identified CTTN (cortactin), an actin binding protein whose phosphorylation is integral to the formation of lamellipodia and invadopodia, as phosphorylated by AURKB and Ephrin A2 (EPHA2), whose dephosphorylation controls cell morphology, adhesion, migration and invasion by modifying the organization of the actin cytoskeleton and influencing the activities of integrins and intercellular adhesion molecules, as dephosphorylated by ACP1. These findings underscore the delicate balance between kinase and phosphatase activities in regulating the actin cytoskeleton broadly and at the cell’s front or “leading edge,” offering new therapeutic targets to disrupt the invasion that is a hallmark of glioblastoma.
BIOM-03. DABRAFENIB AND STEROIDS FOR THE TREATMENT OF ERDHEIM-CHESTER DISEASE WITH EXTENSIVE CENTRAL NERVOUS SYSTEM INVOLVEMENT
Authors: Yuen Carlen , Bao Silin , Aung Mya Sandi , Shishodia Rhea , Kong Xiao-Tang
Published: November 2024

Erdheim-Chester disease (ECD) is an exceedingly rare non–Langerhans cell CD68+ CD1a- S100- histiocytic multi-organ disease. Diagnosis of ECD is often delayed due to non-specific radiographic findings and heterogeneous lesional tissue. Increasingly, the role of genomic alterations is being recognized for both diagnosis and treatment of ECD. More than half of ECD patients harbor the BRAFV600E mutation. Evaluation for this mutation be can falsely negative on immunohistochemical staining and confirmation with molecular analyses is recommended. We present a case of the 44 year-old male with BRAFV600E-positive ECD treated successfully with steroids followed by single-agent dabrafenib.
BIOM-04. SINGLE-CELL RNA SEQUENCING PROTOCOL OF THE HUMAN METASTATIC PROSTATE SPINE TUMOR MICROENVIRONMENT
Authors: Nguyen Annee , Haines Corinne , Price Meghan , Baeta Cesar , Hockenberry Harrison , Johnson Eli , Goodwin C Rory
Published: November 2024

INTRODUCTION

90% of spine tumor patients can develop metastases with debilitating complications, such as sensorimotor dysfunction, paralysis, and spinal instability. As spine tumor patients have limited eligibility to participate in clinical trials and have heterogenous tumor pathology, there is a distinct lack of therapeutic targets and prognostication markers of disease. Thus, there is a distinct need for molecular profiling of spine tumors.

OBJECTIVE

We describe an OR-to-bench-top processing of spine tumors for single-cell omic studies, with samples from a metastatic prostate cancer patient to demonstrate the ability to compare molecular markers and microenvironments of difficult-to-process spine tumors and adjacent normal tissue.

METHODS

Under IRB protocol #Pro00101198, patients undergoing spine surgery with the Department of Neurosurgery at Duke University were consented for tissue collection. Vertebral osseous metastases and adjacent normal tissue were confirmed histologically (H&E, immunohistochemistry) and radiologically (MRI, PET, CT, and x-ray). Tissues were manually and enzymatically homogenized in serum-free media with collagenase A and DNAse I to obtain a single cell suspension. Cells were then filter sterilized, erythrolyzed, counted to determine live-death ratio, resuspended to 10-20 million cells per mL, then cryopreserved for downstream standard library preparation for single-cell sequencing using the 10X genomics platform. Downstream analysis was performed using Seurat pipeline, InferCNV analysis, and SingleR.

RESULTS

P404S and PSA expression confirmed tumor was prostate in origin. Radiological imaging and H&E staining confirmed the presence of T7 osseous metastasis. Uniform manifold approximation and project (UMAP) plots identified 12 unique clusters of immune cell subpopulations between normal and tumorous vertebrae, with their own subsets of differentially expressed genes.

CONCLUSION

We have developed a protocol to generate granular single cell molecular profiling for spine tumors and metastases. Applications of this protocol can aid in identifying therapeutic targets, molecular predictors of disease, and potentiate increased eligibility of patients for clinical trials.
BIOM-05. FUSION TRANSCRIPTOME LANDSCAPE IN GLIOBLASTOMA
Authors: Aulakh Sonikpreet , Xiu Joanne , Kothari Shawn , Sengupta Soma , Glantz Michael , Ahluwalia Manmeet , Nicolaides Theodore , Gilbert Mark
Published: November 2024

BACKGROUND

For most patients with glioblastoma (GBM), no truly effective salvage therapies exist. However, there are compelling examples in oncology where gene fusions lead to functioning oncoproteins that are highly effective targets (ie BCR-ABL1 in CML). Using a large genomic database, we sought to determine the prevalence of fusion transcripts in GBMs.

METHODS

A total of 4392 GBMs were tested at Caris Life Sciences (Phoenix, AZ). Mutations were detected by NextGen sequencing of DNA (592-gene panel or whole exome sequencing); gene fusions were detected by Whole Transcriptome Sequencing. All tumors were wild type for IDH1/2. Significance was tested by Fisher-Exact and ChiSquare and adjusted by Benjamini-Hochberg (q <0.05).

RESULTS

Overall, pathogenic fusions were found in 428 (9.7%). The most prevalent were FGFR3 [N=159 (37%), highest FGFR3:TACC3, N=134], MET [N=92 (21%), highest PTPRZ1:Met, N=31; ST7:MET N=25; CAPZA2: MET, N=23), EGFR [N=87(20%), highest EGFR:SETP14, N=21 and SEC61G: EGFR, N=19], NTRK2 (N=27), PDGFRA (N=23), ROS1 (N=14) and BRAF (N=10). Other actionable fusions including ALK (N=3), NTRK3 (N=3), RAF1(N=3), RET (N=3), NTRK1(N=2) were seen. Tumors with fusions were more likely to have pathogenic gene amplifications including: MET (7.5% vs. 0.7%), FGFR3 (5% vs. 0.2%), CDK4 (17% vs. 11%) and MDM2 (12% and 7.5%) but less frequent EGFR mutation (6.1% vs. 18%), amplification (6.1% vs. 18%) and EGFRvIII mutation (11.9% vs. 22.5%), RB1 (2.9% vs. 11.5%) and TP53mutation (22% vs. 30%) (all q<0.05). EGFR fusions are enriched with EGFR amplification (92%) and EGFRvIII mutation (51%); cMET fusion with MET amplification (40%).

CONCLUSIONS

Comprehensive molecular profiling reveals that approximately 10% of IDH WT GBMs carry oncogenic fusions that may be therapeutic targets. Broad spectrum of observed fusions underscores the need for novel clinical trial designs to allow efficient enrollment for prospective testing of potential targeted agents.
BIOM-06. NOGGIN CONTRIBUTES TO BRAIN METASTATIC COLONIZATION OF LUNG CANCER CELLS
Authors: Yang Seung Ho
Published: November 2024

Brain metastasis is a common complication among patients with lung cancer, yet the underlying mechanisms remain unclear. In this study, we aimed to investigate the pathogenesis of brain metastasis in lung cancer. We established highly colonizing metastatic lung cancer cells, A549-M2, through multiple implantations of A549 human lung cancer cells in the carotid artery of athymic nude mice. Compared to parental cells (M0), M2 cells demonstrated slower growth in culture plates and soft agar, as well as lower motility and higher adhesion, key characteristics of mesenchymal-epithelial transition (MET). Further analysis revealed that M2 cells exhibited decreased expression of epithelial-mesenchymal transition markers, including ZEB1 and Vimentin. M2 cells also demonstrated reduced invasiveness in co-culture systems. RNA sequencing and gene set enrichment analysis confirmed that M2 cells underwent MET. Intriguingly, depletion of Noggin, a BMP antagonist, was observed in M2 cells, and replenishment of Noggin restored suppressed migration and invasion of M2 cells. In addition, Noggin knockdown in control M0 cells promoted cell attachment and suppressed cell migration, suggesting that Noggin reduction during brain colonization causes inhibition of migration and invasion of metastatic lung cancer cells. Our results suggest that lung cancer cells undergo MET and lose their motility and invasiveness during brain metastatic colonization, which is dependent on Noggin.
BIOM-13. COMBINED MGMT PROMOTER METHYLATION AND LOW GENE BODY METHYLATION IS A SUPERIOR PREDICTOR OF ALKYLATING AGENT RESPONSE THAN PROMOTER METHYLATION ALONE IN GLIOBLASTOMA
Authors: Nuechterlein Nicholas , Cimino P J
Published: November 2024

BACKGROUND

The DNA methylation status of the promoter region of O-6-methylguanine-DNA methyltransferase (MGMT) is a critical predictor of temozolomide response in newly diagnosed glioblastoma. However, MGMT-STP27, the dominant method for MGMT promoter methylation determination from methylation array data, considers only methylation probes located in the promoter region. In this study, we propose a robust MGMT classifier that considers MGMT methylation probes in both the promoter and gene body regions.

METHODS

We leveraged glioblastoma DNA methylation and/or gene expression data published by the TCGA (N=312), GLASS (N=276), and Capper et al. (N=535). We correlated MGMT gene expression and MGMT probe methylation in datasets with paired expression and methylation data. We formulated an MGMT methylation score that measured the difference between MGMT promoter probe methylation and gene body probe methylation. We then compared the prognostic utility of this score with the MGMT-STP27 model on patients treated with upfront alkylating agents in multiple datasets in both univariate and multivariate analyses.

RESULTS

We found that MGMT expression was prognostic in TCGA (OS HR=1.5, p=0.027, PFS HR=1.9, p=0.001) and GLASS (OS HR=1.4, p=0.088, PFS HR=1.6, p=0.03) glioblastomas among patients treated with alkylating agents. MGMT expression was negatively correlated with MGMT promoter methylation and positively correlated with MGMT gene body methylation. We defined an MGMT score as the difference between the average MGMT DNA methylation in negatively correlated promoter probes and the average methylation in positively correlated gene body probes. This score was prognostic in the TCGA (OS HR=1.6, p=0.003, PFS HR=1.6, p=0.001) and GLASS (OS HR=3.1, p=0.01, PFS HR=3.9, p=0.004) and was also superior to the MGMT-STP27 classifiers in multivariate analyses (TCGA p=0.03).

CONCLUSION

Overall, we defined an MGMT methylation score that considers promoter and gene body methylation and may be a superior predictor of glioblastoma response to alkylating agents compared to MGMT-STP27.
BIOM-16. A TARGETED GENE EXPRESSION BIOMARKER PREDICTS LOW GRADE MENINGIOMA RECURRENCE AND OVERALL SURVIVAL
Authors: Nguyen Minh , Morshed Ramin , Youngblood Mark , Perlow Haley , Lucas Calixto-Hope , Patel Akash , Palmer Joshua , McCortney Kathleen , Horbinski Craig , Magill Stephen , Chen William , Raleigh David
Published: November 2024

Targeted gene expression profiling improves risk stratification for meningiomas, but the utility of this approach for low grade meningiomas is incompletely understood. To address this, 466 meningiomas that were initially used to validate a 34-gene expression biomarker were combined with 270 previously unpublished samples for an analysis of biomarker performance in newly diagnosed (n=691) or recurrent (n=45) WHO grade 1 meningiomas treated with gross total (GTR) or subtotal resection (STR), and newly diagnosed WHO grade 2 meningiomas treated with GTR. Prediction of local freedom from recurrence (LFFR) or overall survival (OS) was measured using Cox proportional hazards models and the Kaplan-Meier method. The cohort included 736 patients, 69.4% female, with a median age at diagnosis of 58 years. There were 635 WHO grade 1 meningiomas, 498 with GTR and 133 with STR, and 101 WHO grade 2 meningiomas with GTR. The median follow-up was 4.6 years, the local recurrence rate was 12.0% and the rate of death was 8.4%. The biomarker classified 51.5% of meningiomas as intermediate risk and 9.6% as high risk. Combining the biomarker with extent of resection identified 19.7% as unfavorable (intermediate molecular risk with STR or high molecular risk), including 7.4% of newly diagnosed WHO grade 1 meningiomas with GTR. The risk score was prognostic for LFFR overall (hazard ratio per 0.1 increase in risk score 1.89, 95% confidence interval 1.58-2.25) and across WHO grades, extents of resection, and newly diagnosed or recurrent settings. Gene expression risk groups were prognostic for LFFR, with improved outcomes among low molecular risk compared to intermediate molecular risk (Log-rank, p=0.0002) and high molecular risk meningiomas (Log-rank, p<0.0001). These data suggest that a targeted gene expression biomarker can identify low grade meningiomas that are more likely to recur after surgery, possibly changing management for approximately one-fifth of cases.
BIOM-22. SPATIAL, SINGLE-CELL, AND BULK RNA SEQUENCING IDENTIFY MOLECULAR PROGRAMS UNDERLYING MENINGIOMA BRAIN INVASION
Authors: Aggarwal Ayush , Youngblood Mark W , Mirchia Kanish , Najem Hinda J , Magill Stephen T , Heimberger Amy B , Raleigh David R
Published: November 2024

Brain invasion is a negative prognostic factor for meningiomas, but the molecular programs underlying meningioma brain invasion are poorly understood. To address this, we performed transcriptomic analyses of 3 independent datasets: Bulk RNA sequencing from 199 meningiomas (n=33 with brain invasion), single-cell RNA sequencing of 2 regionally distinct samples from the brain tumor interface (BTI) versus tumor core (TC) (n=22,118 single-cell transcriptomes), and spatial RNA sequencing from 6 samples with (n=4) versus without (n=2) brain invasion (n=18,471 spatial transcriptomes). Single-cell and spatial datasets were integrated with Harmony, cell interactions were defined using CellChat, and cross-platform comparisons were performed with the Seurat data integration pipeline. Bulk RNA sequencing revealed enrichment of 1835 genes in meningiomas with brain invasion compared to those without brain invasion, including glial markers (GFAP, NCAN) and markers of extracellular matrix remodeling (PDGFRA, COL9A1). Single-cell RNA sequencing comparison of BTI versus TC meningioma cells identified 2793 genes that were enriched in BTI cells, 268 of which were conserved across bulk and single-cell transcriptomes from brain-invasive meningiomas. Gene ontology enrichment analysis showed molecular programs underlying cell migration and regulation of neurogenesis at the BTI, while glycolysis and antigen presentation programs were enriched in the TC. Cholesterol, CSPG4, and LIF signaling were active in the TC, while SLIT signaling was enriched at the BTI. Spatial RNA sequencing showed enrichment of 439 genes at the BTI, and a conserved set of 12 genes were enriched in BTI meningioma cells across bulk, single-cell, and spatial datasets (TGM2, APOC1, IGFBP6, PLEKHO1, GFPT2, ZYX, IQGAP3, LUM, S100A11, ARPC1B, CDK1, CYCS). Comparison of tumor microenvironment monocytes at the BTI versus TC demonstrated enrichment of 1571 genes that were associated with macrophage migration and activation. These data elucidate molecular programs underlying meningioma brain invasion and provide insights into meningioma intratumor heterogeneity.
BIOM-24. GLIOBLASTOMA DNA ALTERATIONS AND RAPID EARLY PROGRESSION AFTER SURGERY
Authors: Samimi Kayla , Saini Aren , Cullison Kaylie , Herr Janette , Mellon Eric A
Published: November 2024

Glioblastoma is the most common primary brain cancer with overall poor prognosis. In the weeks following initial resection, approximately 50% of glioblastoma patients will demonstrate rapid early progression (REP) on MRI prior to the start of radiation therapy (RT). REP is associated with worse overall survival (OS), however associations between REP and biomarkers in glioblastoma have yet to be evaluated. A single institution sample of 100 patients (age 61.2 years median, 57 males) with a primary diagnosis of glioblastoma were included in this study. Patients underwent gross or subtotal resection followed by RT within 60 days of their surgery. Patients who received biopsy only were excluded. For this analysis, REP was defined as increased nodular enhancement at the border of the resection cavity between the post-operative MRI and RT planning MRI. DNA mutations were collected from commercial next generation sequencing (NGS) results. Biomarkers with a mutational incidence of >10% were used in the analysis, which included TERT promoter (N=80), EGFR (N=38), PTEN (N=40), TP53 (N=36), CDKN2A/2B (N=41), NF1 (N=16), MTAP (N=24), PIK3CA (N=14), and MGMT methylation status (N=32). Statistical analysis was performed using SPSS Statistics 28.0. Of the patients sampled, 45 met the classification of REP. The presence of EGFR alterations (p=0.001) and MGMT methylation (p=0.016) strongly correlated with REP. After multivariate linear regression, only EGFR alterations significantly correlated with REP (p=0.006). There was no significant correlation between REP or overall survival and mutations in TERT promoter, PTEN, TP53, CDKN2A/2B, NF1, MTAP, and PIK3CA. This is the first study to analyze molecular contributors to REP. We identified that EGFR alterations are most strongly correlated with REP. This suggests that patients with EGFR alterations identified on pathology should move rapidly to adjuvant therapies given their propensity to quickly re-grow after resection.
BIOM-26. ROLE OF EXTRA-DOMAIN B FIBRONECTIN IN MODULATING GLIOBLASTOMA CELL INVASIVE PROPERTIES
Authors: Kang Bo Ram , Yun Minji , Bae Eunkyung , Chong Kyuha
Published: November 2024

Glioblastoma (GBM) is a highly malignant tumor characterized by its resistance to current treatment modalities and high recurrence rates. Extra-domain B Fibronectin (EDB-FN), a glycoprotein not found in normal tissues but selectively expressed in the tumor microenvironment, was previously identified by our team as a promising molecular marker for brain tumors, offering potential for both prognostic prediction and therapeutic targeting. However, the specific role and mechanism of action of EDB-FN in GBM cells remain unclear. In this study, we sought to elucidate the potential role of EDB-FN and the underlying mechanisms contributing to GBM malignancy through in vitro investigations. Our findings reveal that silencing EDB-FN in GBM cells leads to a decrease in cell migration, invasiveness, extracellular matrix adhesion ability, and stem cell-like properties. Furthermore, we discovered that FAK and ERK signaling pathways play a crucial role in GBM cell progression in response to EDB-FN. This study underscores the potential of EDB-FN as a specific biomarker for GBM treatment, paving the way for future research in this area.