bluuebunny/crossref_metadata_2025_split huggingface dataset:
OS03.6.A MITOCHONDRIA TRANSFER IN GBM IS MEDIATED BY TGF-Β AND PROMOTES INCREASED INVASIVENESS
Authors: Moreino S S , Storevik S , Pinaz F , Lourido M C , Han J , Augustsson M T , Sarnow K , Joseph J V , Ystaas L A R , Neises L , Meiser J , Bjerkvig R , Daubon T , Hossain J A , Miletic H 
Published: October 2024

Abstract

BACKGROUND
Acquisition of intact mitochondria from the tumor microenvironment (TME) is a ubiquitious phenomenon in tumors of glioblastoma multiforme (GBM),promoting mitochondrial respiration and metabolic pathways tied to proliferation and tumorigenicity 1. The Transforming growth factor β (TGFβ) pathway is a major molecular pathway upregulated in GBM compared to low grade gliomas 2 and recent studies have shown its involvement in invasion associated microtube (MT) formation 3. We hypothesized that TGFβ affects the mitochondria transfer process between GBM and members in the TME, namely astrocytes. We speculated that mitochondria transfer would lead to increased invasiveness as oxidative metabolism has been previously linked to invasion 1. Furthermore, we postulated that inducing metabolic stress conditions via mitochondria depletion would have an impact on the GBM-TME mitochondria transfer process.

METHODOLOGY
We utilised specifically transduced cell lines, immunofluorescence, confocal imaging and flow cytometry to measure mitochondria transfer under TGFβ treatment, MT formation and downstream SMAD signaling. Invasion data was elucidated via collagen invasion assays. Mitochondria depletion experiments in vitro were conducted using electron transport chain inhibitor treatment and flow cytometry. Orthotopic xenograft models were utilised to study this mitochondria depletion in vivo, and immunohistochemical analyses were performed to quantify mitotransfer.

RESULTS
Our in vitro results show that treatment of GBM - astrocyte cocultures with TGFβ directly impacted mitotransfer rates, MT formation and downstream SMAD signaling. Results obtained from collagen assays show promoted invasion in GBM with acquired mitochondria from the TME. Our mitochondria depletion model experiments show an amplified transfer of mitochondria from the TME by mitochondria deficient GBM cells - further characterizing the reliance of GBM on this process to promote its aggressive tumorigenic phenotype.

CONCLUSION
We identified a new mediating role of TGFβ in GBM interactions with the TME and canonical SMAD as a specific downstream signaling pathway involved. Our collagen invasion and mitochondria depletion studies also demonstrated the importance of mitochondria transfer from TME astrocytes to GBM in cellular functions related to proliferation, invasion and cell rescue.

REFLECTION
The findings of our study provide new insights into GBM disease progression and therapy resistance, indicating new opportunities for treatment development.
OS04.5.A SEXUALITY IN PATIENTS WITH LOW-GRADE GLIOMAS
Authors: Buunk A M , Siebenga F F , Bosma-Bleeker M H , Spikman J M 
Published: October 2024

Abstract

BACKGROUND
Patients diagnosed with a low-grade glioma (LGG) face various challenges that influence their daily functioning, such as mood disorders, cognitive decline and fatigue. However, little is known about problems concerning sexuality and intimacy in patients with LGG, although these can have a profound negative impact on quality of life and well-being. Also, related factors (disease characteristics, cognitive functions, emotional problems) are unknown. Therefore, the aim of the present study was twofold: 1) investigate changes in sexuality after diagnosis of and surgery for LGG, and 2) examine if sexuality changes are related to disease characteristics (tumor volume and localisation), cognitive impairments and mood problems.

MATERIAL AND METHODS
Patients with diffuse oligodendrogliomas and astrocytomas (WHO grades II and III) were included. After surgery, before the start of adjuvant therapy, cognitive functions and mood were investigated with neuropsychological tests and questionnaires respectively. At least 3 months after proton therapy, sexuality was investigated with the Brain Injury Questionnaire of Sexuality (BIQS), with lower scores indicative of decreases in sexual functioning compared to pre-diagnosis. The subscales Sexual Functioning (8 items, range 8-40, score between 8-23 = indicative for negative change) and Relationship Quality & Self-Esteem (5 items, range 5-25, score between 5-14 = indicative for negative change) were used. Tumor volume and location were recorded. Descriptive statistics, between-group comparisons and correlational analyses were used.

RESULTS
46 patients with LGG were included (mean age = 43.2 years, 32.6% female). Compared to pre-diagnosis, 71.7% of all patients reported decreased sexual functioning and 54.3% lower relationship quality and self-esteem. On item level, most frequent changes were decreased sex drive (41.3%), lower importance of sexuality (43.5%), decreased ability to give partner sexual satisfaction (47.8%), and lower frequency of sexual activities (67.4%). Correlational analyses and between-group comparisons yielded no significant associations between sexuality changes and tumor volume, localisation, cognitive impairments, and mood problems.

CONCLUSION
Changes in sexuality were found in over 70% of the patients with LGG, with most frequent changes being lower frequency and the decreased ability to give a partner sexual satisfaction. Decreases compared to pre-diagnosis did not appear to be closely connected to disease-related, psychological or cognitive factors. Consequently, our results emphasize the need to consider sexual health in all patients with LGG in clinical practice, as neglecting sexuality can lead to unnecessary sexual problems, feelings of loneliness and isolation. Future studies could examine the effect of adjuvant therapies, such as proton therapy, on sexuality more closely.
OS06.8.A PROSPECTIVE STUDY ON THE IMPACT OF THE GUT MICROBIOME COMPOSITION TO PATIENT’S RESPONSE TO STANDARD TREATMENT IN PCNSL
Authors: Hernández-Verdin I , Kirasic E , Mokhtari K , Barillot N , Rincón de la Rosa L , Sourdeau E , Abada Y , Le Tarff-Tavernier M , Choquet S , Houillier C , Hoang-Xuan K , Alentorn A 
Published: October 2024

Abstract

BACKGROUND
Gut microbiota has gained attention as a potential modulator of occurrence, progression, and response to cancer therapy, with host immune regulation as one potential mechanism. Primary central nervous system lymphoma (PCNSL) is a rare and distinct entity within diffuse large B-cell lymphoma whose treatment relies on a high-dose methotrexate (HD-MTX) regimen with or without consolidation. However, whether there is a specific microbiota composition association with treatment response and clinical outcomes remains incompletely understood.

MATERIAL AND METHODS
To identify the relationship between gut microbiome composition and response standard treatment in patients with PCNSL, we conducted a prospective study of PCNSL patients, included in the clinical trial NCT02313389 and the ancillary study NCT04253496 from 2020 to 2023 (patients aged more than 60 years, HD-MTX based induction and randomized HD-MTX-based maintenance versus follow-up without consolidation). Stool and cerebrospinal fluid (CSF) samples (n=49) were collected before (n=35) or after (n=14) therapy initiation to perform metagenomic and flow cytometry analyses. Clinical data, including treatment response, progression-free survival (PFS), and overall survival (OS), were collected and correlated with microbiome composition and immune cell content in CSF.

RESULTS
Analysis of paired samples (before versus after HD-MTX), revealed slight changes in microbial composition, especially the loss of a bacteria belonging to the Verrucomicrobiota Phylum. Unsupervised clustering on microbial data revealed two microbial communities associated with significantly distinct PFS (33.65 vs 7.60 months, p=0.001) and OS (36.75 vs 23.95 months, p=0.005) in PCNSL patients. Linear discriminant analysis Effect Size and differential abundance analysis between these communities revealed a specific organism belonging to the Bacteroidota Phylum whose enrichment is associated with improved OS and PFS at both univariate and multivariate models. Further stratifying patients according to this bacteria content showed an association with CD8 T cell infiltration to the CSF, suggesting a link between host immune cell regulation and gut microbiome composition.

CONCLUSION
Our findings suggest that gut microbiome communities may influence responses to standard treatment and clinical outcomes in PCNSL patients. Moreover, the identification of this particular microorganism could potentially provide a basis for patient stratification and guide personalized therapeutic strategies. We are currently working in a validation cohort to reinforce our findings and to elucidate the mechanisms underlying the interaction between the gut microbiome, the host immune regulation, and the treatment response.
OS07.6.A CONNEXIN-MEDIATED NETWORKS IN GLIOBLASTOMA COMMUNICATION
Authors: Strobel H , Mulaw M , Karpel-Massler G , Peraud A , Debatin K , Westhoff A 
Published: October 2024

Abstract

BACKGROUND
Recent data suggest that Glioblastoma (GB), a highly aggressive malignant brain tumor, mimics cellular interactions found in healthy brain structures. GB cells exhibit, among other types of interaction, extensive membrane protrusions linked through gap junctions (GJs), tightly regulated intercellular channels predominantly comprised of connexins (Cxs). These channels facilitate the exchange of small molecules and also provide platforms for signaling hubs. Consequently, GJs/Cxs interconnect GB cells into expansive communicative networks that substantiate tumor growth, migration, and influence the response to injury. In this investigation, we delineated the precise composition of Cxs in brain tumors, with a specific emphasis on GB, unraveling their nuanced functional roles.

MATERIAL AND METHODS
Using our exclusive repository of primary brain tumor specimens, we screened for the expression of all 21 known Cxs. By comparing our findings with publicly available RNA sequencing data sets and performing various in silico analyses, we identified Connexin 26 (Cx26) as an interesting candidate. The role of Cx26 in a defined signaling network was further elucidated by pharmacological modulation as well as genetic knock-out models.

RESULTS
We found a multitude of Cxs expressed in brain tumors, many of them dysregulated when compared to their expression in healthy brain cells. Additionally, by utilizing in silico analyses of publicly accessible RNA sequencing datasets, the expression of Cx26 emerges as a potential biomarker, correlating significantly with the overall survival of GB patients. Notably, subsequent analysis affirms that Cx26 expression is highest in grade IV brain tumors and in GBs, it exhibits a pronounced association with the mesenchymal subtype. Within the tumor, its expression is most notably concentrated in the tumor core and aligns with the recently described Connectivity Signature. The genetic manipulation of Cx26 exerted a profound impact on cellular behavior. Notably, the knock-out of Cx26 significantly impeded the cells’ ability to establish morphological networks when cultured in the presence of an extracellular matrix substrate. Furthermore, pharmacological modulation of these cells suggests Cx26 as a prospective mediator in facilitating TGF-β1-associated cell-cell communication.

CONCLUSION
Cx26 is a novel mediator of connectivity that facilitates cell-cell interaction in the recently described network that characterizes a particular aggressive GB subpopulation. This effect seems to be associated with the tight regulation of the TGF-β1 signaling cascade.
OS07.7.A DISSECTING SPATIAL DIVERSITY OF GLIOBLASTOMA GENOTYPES
Authors: Zhang J , Joshi T , Hambardzumyan D , Heiland D 
Published: October 2024

Abstract

BACKGROUND
Glioblastoma (GBM) remains an intractable cancer characterized by significant inter- and intra-patient heterogeneity. Recent research has established connections between key genetic drivers and distinct transcriptional profiles in GBM, yet the interactions between genetic changes and the transcriptional and spatial heterogeneity remain unclear. This study used genetically engineered mouse models, coupled with spatially resolved and single-cell RNA sequencing, to explore how specific genetic alterations influence the tumor microenvironment (TME) and cellular responses spatially.

MATHODS
We used nestin-Tva C57BL/6 mice and generated de novo GBM using overexpression of oncogenes in combinations with short hairpin RNAs (shRNAs) or deletion to various tumor suppressors, including Tp53, Cdkn2A, and Pten. We modeled key driver mutations for GBM: PDGFB, NF1, and EGFR. We conducted single-cell RNA sequencing, combined with spatially resolved transcriptomics and proteomics. Data integration techniques, including horizontal (mutual nearest neighbors) and vertical (weighted nearest neighbors) approaches, were used and analyzed with the SPATA2 software. Advanced computational methods, such as graph neural networks and single-cell deconvolution, were applied to examine GBM genotypes and the spatial variability within tumors and their TMEs.

RESULTS
Our findings revealed persistent cellular heterogeneity among tumor cells under various genetic conditions. However, specific genetic alterations influenced the cells toward dominant transcriptional states. NF1 and EGFR mutations resulted in shifts towards MES and AC-like states, respectively, unlike PDGFB, which promoted a NPC/OPC-like state. These transcriptional shifts were strongly associated with distinct microenvironmental changes, such as enhanced neuronal signaling in PDGFB-driven GBMs versus pronounced immune infiltration in NF1 and EGFR models. Utilizing weighted co-expression network analysis (WGCNA) and gene set enrichment analysis (GSEA) alongside spatial-niche deconvolution, we identified a mesenchymal transition leading to an immunosuppressive TME in NF1-driven GBMs and increased lymphocyte presence in EGFR-amplified GBMs, especially around blood vessels. Similar spatial patterns were observed in human spatially resolved transcriptomic data, highlighting the complexity and variability of genetic drivers in human GBMs.

CONCLUSION
Our genetically engineered mouse models provide a valuable platform for investigating GBM with defined driver mutations. By leveraging sophisticated analytical techniques and computational modeling, this study underscores the potential to elucidate the interactions between genetic drivers and the tumor microenvironment. Our approach paves the way for developing targeted therapies and precision medicine strategies in GBM.
OS09.6.A METHYLATION CLASSIFICATION AND MOLECULAR LANDSCAPE OF H3 WILDTYPE SPINAL CORD GLIOMA
Authors: Chai R , Chen H , Chang Q , Wang Y , Wang J 
Published: October 2024

Abstract

BACKGROUND
Spinal cord H3-K27M-wildtype gliomas (H3WT-SCG) are rare and heterogeneous tumors whose pathological classification remain challenging.

MATERIAL AND METHODS
We comprehensively characterized 55 H3WT-SCG patients through DNA methylation array, whole-exome/transcriptome sequencing, proteomics, and single-cell RNA sequencing.

RESULTS
Methylation-based classification revealed six molecular classes in the enrolled cohort, including spinal cord pilocytic astrocytomas (PA-SPINE, n=29), normal-like (high-immune, n=10), Diffuse leptomeningeal glioneuronal tumour (DLGNT, n=10), subependymaoma (SUBEPN-SPINE) (n=3), glioblastoma-like (GBM-like, n=2), and pleomorphic xanthoastrocytoma-like (PXA-like) (n=2). To our surprise, the molecular classification is inconsistent with traditional histologic diagnoses in 61.8% of cases, and the most traditional diffuse astrocytoma classified into PA-SPINE (14/24) or normal-like (5/24). We found that compared to traditional methods, methylation-based classification more accurately reflects the molecular features and patient prognosis in H3WT-SCGs, evidenced by the enrichment of BRAF fusions in PA-SPINE and DLGNT (p-value 0.04), and the enrichment of chromosomes 1p loss (p-value 6.5e-08) and 1q gain (p-value 3.6e-05) in DLGNT. The largest subclass, PA-SPINE, can be further divided into adult (older than 18 year old) and pediatric subtypes, with differences in DNA methylation profile. The adult case has lower BRAF fusion frequency (p-value = 1.4e-03), shorter tumor length (p-value = 3.7 e-04) and longer progress-free- survival (p-value = 0.062). Moreover, adult PA-SPINE neoplastic cells exhibited a less differentiated status, characterized by higher expression of EGFR and neuronal markers, as well as lower expression of cytokines and chemokines than pediatric cases. Single cell analysis showed that adult cases demonstrated reduced infiltration of monocyte-derived macrophages and proliferative myeloid cells compared to pediatric cases.

CONCLUSION
This study revealed molecular classes of H3WT-SCGs that precisely reflect the clinical and molecular characteristics of these tumors and further highlight the differences in clinical, molecular, biological, and cellular features between adult and pediatric PA-SPINE.
OS10.4.A CXCL1 MEDIATES LEPTOMENINGEAL METASTASIS GROWTH
Authors: Osman A , Remsik J , Wijetunga A , Snyder J , Manoranjan B , Nobre A , Freret M , Guber D , Chabot K , Piedrafita-Ortiz S , Tong X , Wang H , Li M , Yang J , Boire A 
Published: October 2024

Abstract

BACKGROUND
Leptomeningeal metastasis (LM) is a fatal neurological complication of cancer characterized by the entry of metastatic cancer cells originated from solid or hematologic tumors into the cerebrospinal fluid (CSF)-filled leptomeningeal compartment encasing the brain and the spinal cord. LM occurs in 5-20% in patients with solid tumors, especially those with breast cancer, lung cancer, melanoma. Untreated LM patients succumb within 4-6 weeks after diagnosis, or 2-5 months when they are treated with the current available therapies. To date, the only efficacious life-prolonging intervention was the application of proton craniospinal irradiation (pCSI) as demonstrated in the recent clinical trial, NCT04343573, with an average overall survival of 9 months. While a cohort of pCSI-treated patients survived over 18 months (responders), another cohort did not respond to pCSI and succumbed to the disease within 3 months post-treatment (non-responders). In this project, we aimed to characterize the molecular basis of pCSI response to turn the non-responders into responders.

MATERIAL AND METHODS
We performed proteomic analyses on serially collected CSF from LM patients at baseline (before pCSI), and multiple time points post-treatment. We further established syngeneic mouse models of LM-CSI to define the molecular basis of pCSI resistance.

RESULTS
We found that pCSI resulted in a significant drop in the levels of the chemokine CXCL1, a CXC-motif chemokine with elevated baseline levels after the onset of LM. Patients with significantly higher CSF CXCL1 levels prior to pCSI had worse central nervous system (CNS) progression-free survival. Using our preclinical LM mouse models, we found that both the cancer and host cells, namely macrophages, choroid plexus epithelial cells, and leptomeningeal fibroblasts, were a source of CXCL1. Genetic manipulation of Cxcl1expression in cancer cells or host revealed that the CXCL1 produced by the cancer cells was an essential factor for their growth in the leptomeninges. Moreover, we found that a subset of cancer cells expressed a receptor for CXCL1 - CXCR2 - and transcriptomic profiling of this rare population revealed an enrichment in pathways associated with cell cycle progression. Finally, intrathecally delivered CXCR2 antagonist hampered the LM growth.

CONCLUSION
Our results indicate that CXCL1/CXCR2 signaling axis regulates LM growth and suggests interruption of this signaling axis as a possible actionable therapeutic intervention to halt LM progression.
OS10.6.A THE IMPACT OF PATIENT-REPORT OUTCOME QUESTIONNAIRE PARTICIPATION ON OVERALL SURVIVAL IN PATIENTS WITH BRAIN METASTASES
Authors: David S , Cialdella F , Nagtegaal S H J , van Grinsven E E , Philippens M E P , Verhoeff J J C 
Published: October 2024

Abstract

BACKGROUND
The COIMBRA (NCT05267158) is a prospective, observational study of patients with brain metastases (BMs) which collects extensive longitudinal clinical, radiological and patient-report outcome (PRO) data before and after radiotherapy (RT). After enrollment, patients can make decisions whether to participate in additional data collection, for example in providing Quality of Life (QoL) data. Validated questionnaires, such as the EORTC QLQ-C30 among others, are designed to measure different aspects of QoL of cancer patients and thus gain insights into their mental, physical, and social well-being. In this study, we investigate whether patient consent to filling out QoL-questionnaires has an effect on overall survival (OS).

MATERIAL AND METHODS
We included 377 patients with BMs who were referred for stereotactic radiosurgery (SRS) and enrolled in the COIMBRA study in the UMC Utrecht, between 2019 April to 2023 April. Among them, 276 patients consented to providing PROs, while 101 did not. OS was calculated from the start of RT and analyzed using Kaplan-Meier analysis and Cox regression.

RESULTS
The median OS for patients who consented to PROs was 17.7 months, significantly higher than the 12.3 months for those who did not consent (log-rank test p=0.008). The effect of PRO consent on OS was significant in both univariate (HR = 0.62; p &lt;0.001) and multivariate Cox regression (HR=0.72; p=0.02), the latter correcting for age, KPS, primary cancer type, chemotherapy, surgery, and time from diagnosis to receiving radiotherapy. The 1-, 2- and 5-year survival rates for the PRO consented vs non-consented were: 68% vs 50%; 46% vs 33% and 34% vs 14%, respectively.

CONCLUSION
Our results show a significant relationship between patient consent to filling out PRO questionnaires and longer OS in patients with BMs undergoing SRS. This suggests that patient engagement, as measured by willingness to participate in PROs, may be indicative of broader health behaviors linked to improved survival. However, it is important to consider that the act of participation could itself be influenced by underlying factors we did not investigate, which may predispose patients to both decreased engagement and worse outcomes. For example, factors such as lower levels of overall health literacy, lower socioeconomic status, the distribution of the lesions might contribute to lower participation and independently affect survival outcomes. Therefore, while fostering patient engagement remains a promising approach to enhance study involvement, our understanding of the complex interplay between patient characteristics and their participation in care processes must be further studied. These results may indicate that any study for which active patient participation is required might thereby introduce a selection bias for patients with better overall health and expected survival.