Overall Survival In Glioblastoma Patients Research Articles

The prognostic importance of glioblastoma size and shape

PurposeExtent of resection, MGMT promoter methylation status, age, functional level, and residual tumor volume are established prognostic factors for overall survival in glioblastoma patients. Preoperative tumor volume has also been investigated, but the results have been inconclusive. We hypothesized that the surface area and the shape were more representative of the tumor’s infiltrative capacities, and thus, the purpose of this study was to assess the prognostic value of tumor size and shape in patients with glioblastoma.MethodsIn total, 271 patients with primary, unifocal glioblastoma were included from two centers in Norway and Sweden, respectively. All tumors were automatically segmented on preoperative MRI scans and manually validated. Tumor volume was used as a measurement of size, whereas sphericity index and area-to-volume ratio defined the shape complexity of the tumor. Contact surface area of the tumor was considered a measurement of both size and shape. Multivariable Cox proportional hazards models were used to assess the prognostic value of the respective tumor measurements, with previously established prognostic factors as covariates.ResultsThere were no associations between preoperative tumor volume and overall survival. Contact surface area (HR = 1.013, p = 0.002) and sphericity index (HR = 2.223, p = 0.001) were both significant independent prognostic factors for survival in the multivariable Cox models. Contact surface area was also associated with MGMT promoter methylation (p = 0.039) and extent of resection (p = 0.017).ConclusionTumor shape complexity appears to be an independent prognostic factor in glioblastoma patients and may also be associated with MGMT promoter methylation status and extent of surgical resection.

EPID-23. HISTORY OF TYPE III IMMUNE HYPERSENSITIVITY IMPROVES SURVIVAL IN GLIOBLASTOMA

Abstract Preexisting atopy, particularly allergic rhinitis, is consistently associated with decreased risk of glioma, and there is evidence that preexisting autoimmune conditions may also decrease risk. Glioblastoma is both locally and systemically immunosuppressive and, unlike many other forms of cancer, its initiation is not strongly linked with chronic inflammation. Therefore, history of immune hypersensitivity could be associated with improved anti-glioma immunosurveillance. We leveraged Surveillance, Epidemiology and End Results (SEER) data combined with Medicare claims to investigate the effect of preexisting immune hypersensitivities on overall survival of glioblastoma patients receiving resection, radiation, and temozolomide (standard of care, or SOC) from 2008-2019. Patients <66 years of age, enrolled in Medicare Advantage, not continuously enrolled in Medicare Part A/B, missing follow-up, reported by autopsy/death certificate only, or who did not receive surgery were excluded. Prior history of immune hypersensitivity (≥6 months prior to primary cancer diagnosis) was identified by ICD-9/ICD-10 codes. Treatment pattern was determined using ICD-9/ICD-10 and HCPCS/CPT codes. Conditions were classified into broad immune hypersensitivity types: type I (IgE-mediated, including atopy), type II (IgG- or IgM-mediated), type III (immune complex-mediated, including lupus and rheumatoid arthritis), and type IV (cell-mediated). Survival comparisons were made using Cox proportional hazard models adjusted for demographics, extent of resection, and Charlson comorbidity score (excluding immune conditions) to estimate hazard ratios, 95% confidence intervals, and p-values. Overall, 44% of 3,426 glioblastoma patients who received SOC had an immune hypersensitivity (type I: 33%, type II: 4%, type III: 8%, and type IV: 15%). These conditions were significantly more common in females (47% vs 41%, p<0.001). After adjustment, only type III immune sensitivity was associated with improved OS (HR=0.81, 95% CI:0.71-0.92, p=0.002). These results suggest that underlying immune-complex mediated hypersensitivity may improve treatment response and prognosis in glioblastoma, and that these pathways could potentially be exploited for therapy.

IMMU-61. THE LAST OF US: A FUNGI BASED DENDRITIC CELL VACCINE

Abstract BACKGROUND Glioblastoma (GBM) is the most prevalent primary malignant brain tumor in adults. The current standard treatment for newly diagnosed GBM involves maximal surgical resection followed by radiotherapy and temozolomide. Despite these interventions, the median overall survival for GBM patients remains approximately 15 months, highlighting the critical need for innovative therapeutic approaches. OBJECTIVE Our laboratory has previously developed a subcutaneous autologous tumor vaccine incorporating irradiated (IR) tumor cells with phagocytosis-stimulating ligands (Mannan-BAM), toll-like receptor (TLR) agonists, and an immunostimulant anti-CD40 antibody (collectively termed MBT). This combination has shown efficacy in mouse models of colon carcinoma, breast cancer, melanoma, and, more recently, gliomas. Our study aimed to create a dendritic cell (DC) vaccine using this strategy. METHODS To evaluate whether MBT could induce the maturation of DCs in vitro, we harvested BMDCs from mice and co-cultured them in the presence of MBT-tagged irradiated tumor cells. We then analyzed the maturation markers using flow cytometry and assessed cytokine production via ELISA. To test the efficacy of this approach in vivo, we utilized two different murine glioma models (SB28 and GL261). RESULTS Using flow cytometry, we observed a significant upregulation of important co-stimulatory molecules. Additionally, ELISA analysis demonstrated that MBT-treated DCs significantly increased the secretion of Type 1 cytokines while limiting the secretion of the regulatory cytokine IL-10. MBT-primed DCs combined with immune checkpoint inhibitor PD-1 increased mouse survival in a glioma model compared to WT mice. However, mice eventually succumbed to cerebral edema. Histology demonstrated significant treatment effects. CONCLUSION Our results demonstrate that MBT effectively matures DCs ex-vivo. Further research is required to immunophenotype the response to vaccination in glioma models and explore ways to overcome resistance.

BIOM-74. IDENTIFICATION OF EMP2 AS A TARGETABLE BIOMARKER IN GLIOBLASTOMA TUMORS RESISTANT TO ANTI-ANGIOGENIC THERAPIES

Abstract BACKGROUND The role of Epithelial Membrane Protein-2 (EMP2) in mediating resistance to current anti-angiogenic drugs in the treatment of glioblastoma (GBM) is an intriguing hypothesis that may provide insights into improving the limited survival benefits observed in current therapies. Investigating the interaction between EMP2 and anti-angiogenic drugs such as bevacizumab or Aflibercept could lead to a better understanding of the mechanisms underlying resistance, potentially opening up new avenues for more effective treatment strategies. OBJECTIVE To use EMP2 as a targetable biomarker for anti-VEGF resistance and test combination therapy with anti-VEGF (Aflibercept or bevacizumab), and a novel anti-EMP2 mAb in SB28 and GL261 GBM mouse models. METHODS Tumor tissue was collected prospectively from patients undergoing surgery for suspected glioblastoma and stained for EMP2 and HIF-2a using standard immunohistochemistry. Patients had banked tumor tissue both before and after bevacizumab treatment with 3 months of clinical and radiologic follow-up available. To establish syngeneic models, 10-week-old mice were subcutaneously implanted with murine SB28 or GL261 GBM cells. RESULTS Immunohistochemistry conducted on pre- and post-bevacizumab-treated patient samples revealed an increase in EMP2 and HIF-2a protein expression post-treatment. This increase in EMP2 expression correlated with reduced survival time. Similarly, the in vivo models showed a significant upregulation in both markers in the Aflibercept-treated cohort compared to the control. Treatment with either polyclonal sera to VEGF or Aflibercept failed to reduce tumor load or provide a therapeutic benefit. However, combination therapy with Aflibercept and anti-EMP2 mAb was found to significantly reduce tumor volume and weight in both SB28 and GL261 tumors. These findings highlight the potential effectiveness of combination therapies targeting EMP2 and VEGF in reducing tumor load in GBM. CONCLUSION Our results suggest that EMP2 can be a promising new therapeutic target that can be combined with anti-VEGF treatment to potentially increase overall survival in GBM patients.

EPID-12. NEIGHBORHOOD SOCIOECONOMIC STATUS PREDICTS SURVIVAL IN GLIOBLASTOMA: A SINGLE CENTER COHORT STUDY

Abstract BACKGROUND Glioblastoma (GBM) is the most common primary brain malignancy. Despite recent progress in treatments, prognosis for patients remain poor. Recent literature has suggested the association of GBM outcomes and socioeconomic status. However, there is limited evidence regarding the association of neighborhood-level socioeconomic status on GBM outcomes. OBJECTIVE To investigate the impact of neighborhood-level socioeconomic status on GBM outcomes. METHODS We retrospectively reviewed all adult GBM patients at a single institution from 2008 to 2023. Patient addresses underwent geospatial analysis and Area Deprivation Index (ADI) was extracted. Univariable and multivariable survival analyses were performed. A Cox proportional hazards model was used to assess the effect of ADI and other socioeconomic variables while controlling for a priori selected clinical variables with known relevance to survival. RESULTS In total, 1492 patients met inclusion criteria. The average age at diagnosis was 62±14.2 years with a median overall survival of 12.1 [Interquartile Range (IQR) 5-22] months. The median ADI was 66 (IQR 46-84). Patients with high socioeconomic deprivation (ADI>75) were less likely to receive chemotherapy (92% vs 96%, p=.03), and had worse overall survival compared to patients with low socioeconomic deprivation (10 vs 13 months, p=.001). In the multivariable model, patients with high ADI had worse overall survival (hazard ratio [HR], 1.42; 95% confidence interval [CI], 1.16-1.73, p<.001). To account for changes in WHO guidelines, we implemented the model on patients diagnosed between 2017-2023 and findings were consistent (HR 1.34, 95%CI 1.07-1.68, p=.011). CONCLUSIONS We present the largest study reporting the effect of neighborhood-level socioeconomic status on overall survival of GBM patients. Neighborhood-level socioeconomic status provides the most accurate capture of the patient-level socioeconomic determinants of health. Patients with higher ADI have worse overall survival after controlling for other socioeconomic and clinical variables. These results suggest significant association between neighborhood-level socioeconomic status and overall survival in GBM patients.

Opportunities and Challenges of Small Molecule Inhibitors in Glioblastoma Treatment: Lessons Learned from Clinical Trials.

Glioblastoma (GBM) is the most prevalent central nervous system tumour (CNS). Patients with GBM have a dismal prognosis of 15 months, despite an intensive treatment schedule consisting of surgery, chemoradiation and concurrent chemotherapy. In the last decades, many trials have been performed investigating small molecule inhibitors, which target specific genes involved in tumorigenesis. So far, these trials have been unsuccessful, and standard of care for GBM patients has remained the same since 2005. This review gives an overview of trials investigating small molecule inhibitors on their own, combined with chemotherapy or other small molecule inhibitors. We discuss possible resistance mechanisms in GBM, focussing on intra- and intertumoral heterogeneity, bypass mechanisms and the influence of the tumour microenvironment. Moreover, we emphasise how combining inhibitors can help overcome these resistance mechanisms. We also address strategies for improving trial outcomes through modifications to their design. In summary, this review aims to elucidate different resistance mechanisms against small molecule inhibitors, highlighting their significance in the search for novel therapeutic combinations to improve the overall survival of GBM patients.

Association between dichotomized VASARI feature and overall survival in glioblastoma patients: a single-institution propensity score matching analysis

ObjectivesThis study aimed to investigate the intra- and inter-observer consistency of the Visually Accessible Rembrandt Images (VASARI) feature set before and after dichotomization, and the association between dichotomous VASARI features and the overall survival (OS) in glioblastoma (GBM) patients.MethodsThis retrospective study included 351 patients with pathologically confirmed IDH1 wild-type GBM between January 2016 and June 2022. Firstly, VASARI features were assessed by four radiologists with varying levels of experience before and after dichotomization. Cohen’s kappa coefficient (κ) was calculated to measure the intra- and inter-observer consistency. Then, after adjustment for confounders using propensity score matching, Kaplan-Meier curves were used to compare OS differences for each dichotomous VASARI feature. Next, patients were randomly stratified into a training set (n = 211) and a test set (n = 140) in a 3:2 ratio. Based on the training set, Cox proportional hazards regression analysis was adopted to develop combined and clinical models to predict OS, and the performance of the models was evaluated with the test set.ResultsEleven VASARI features with κ value of 0.61–0.8 demonstrated almost perfect agreement after dichotomization, with the range of κ values across all readers being 0.874–1.000. Seven VASARI features were correlated with GBM patient OS. For OS prediction, the combined model outperformed the clinical model in both training set (C-index, 0.762 vs. 0.723) and test set (C-index, 0.812 vs. 0.702).ConclusionThe dichotomous VASARI features exhibited excellent inter- and intra-observer consistency. The combined model outperformed the clinical model for OS prediction.

Genetic Prognostic Factors in Adult Diffuse Gliomas: A 10-Year Experience at a Single Institution.

Gliomas are primary brain lesions involving cerebral structures without well-defined boundaries and constitute the most prevalent central nervous system (CNS) neoplasms. Among gliomas, glioblastoma (GB) is a glioma of the highest grade and is associated with a grim prognosis. We examined how clinical variables and molecular profiles may have affected overall survival (OS) over the past ten years. A retrospective study was conducted at Sina Hospital in Tehran, Iran and examined patients with confirmed glioma diagnoses between 2012 and 2020. We evaluated the correlation between OS in GB patients and sociodemographic as well as clinical factors and molecular profiling based on IDH1, O-6-Methylguanine-DNA Methyltransferase (MGMT), TERTp, and epidermal growth factor receptor (EGFR) amplification (EGFR-amp) status. Kaplan-Meier and multivariate Cox regression models were used to assess patient survival. A total of 178 patients were enrolled in the study. The median OS was 20 months, with a 2-year survival rate of 61.0%. Among the 127 patients with available IDH measurements, 100 (78.7%) exhibited mutated IDH1 (IDH1-mut) tumors. Of the 127 patients with assessed MGMT promoter methylation (MGMTp-met), 89 (70.1%) had MGMT methylated tumors. Mutant TERTp (TERTp-mut) was detected in 20 out of 127 cases (15.7%), while wildtype TERTp (wildtype TERTp-wt) was observed in 107 cases (84.3%). Analyses using multivariable models revealed that age at histological grade (p < 0.0001), adjuvant radiotherapy (p < 0.018), IDH1 status (p < 0.043), and TERT-p status (p < 0.014) were independently associated with OS. Our study demonstrates that patients with higher tumor histological grades who had received adjuvant radiotherapy exhibited IDH1-mut or presented with TERTp-wt experienced improved OS. Besides, an interesting finding showed an association between methylation of MGMTp and TERTp status with tumor location.

Investigating Causal Genetic Effects on Overall Survival of Glioblastoma Patients using Normalizing Flow and Structural Causal Model.

Glioblastoma (GBM) is the most common and aggressive brain tumor with short overall survival (OS) of about 15 months. Understanding the causal factors affecting the patient survival is crucial for disease prognosis and treatment planning. Although previous efforts on survival prediction using multi-omics data has yielded useful predictive models, the causation of the correlated genetic risk factors has not been addressed. Recent advances in causal deep learning models enable the study of causality from complex dataset. In this paper, we leverage the recently proposed structural causal model (SCM) with normalizing flows parameterized by deep networks to perform the counterfactual query to investigate the causal relationship between gene mutation and OS with the presence of other confounders including sex, age and radiomics features. The query amounts to the question that what the survival days will be if the gene mutation status has been changed, i.e., from mutant to non-mutant and vice versa. The trained causal model will infer the counterfactual outcome given the intervention on specific gene mutation. We apply multivariate Cox-PH model to find the genes associated with survival, and investigate the causal genetic effect by comparing the original and counterfactual survival days in a bi-directional fashion. Particularly, the following two scenarios are considered: (1) intervention on a specific gene with non-mutant status to generate the counterfactual survival days as if the gene is mutant, with which the original survival days of the subjects with that mutant gene will be compared; (2) intervention on the gene with mutant status and perform the comparison with survival days of subjects with that non-mutant gene. Our experimental results show that no causation of two correlated genes (NF1, RB1) was revealed in the cohort (n=181), while their genetic effects on OS in terms of prolonging or shortening are generally in accordance with clinical findings.

Abstract 2508: EMP2 is a targetable biomarker in GBM tumors resistant to anti-angiogenic therapies

Abstract Background: Glioblastoma (GBM) is characterized as the most aggressive and lethal primary brain tumor. One of the hallmarks of GBM tumor growth and progression lies within the proangiogenic tumor microenvironment. Current anti-angiogenic drugs such as the anti-VEGF antibody take effect by inducing tumor cell starvation, leading to a functional normalization of the tumor vasculature. However, the survival benefits of anti-angiogenic drugs have been very limited. To this end, we hypothesized that the tetraspan Epithelial Membrane Protein-2 (EMP2) may help mediate resistance. Objective: We hypothesize that Epithelial Membrane Protein-2 may serve as a targetable biomarker for anti-VEGF resistance. We further explored the effectiveness of combination therapy in SB28 and GL261 GBM mouse models using anti-VEGF drug, Aflibercept, with a novel anti-EMP2 monoclonal antibody (mAb). Results: Tumor tissue was collected prospectively from patients undergoing surgery for suspected glioblastoma and stained for EMP2 and HIF2a using standard immunohistochemistry. Patients had banked tumor tissue both prior to and after bevacizumab treatment with 3 months of clinical and radiologic follow-up available. Bevacizumab treatment increased EMP2 protein expression. This increase in EMP2 correlated with reduced mean survival time post-bevacizumab therapy. Similarly, HIF-2a showed increased expression post-bevacizumab treatment and showed expression in both tumor and stromal cells. Limited animal models exist for anti-VEGF therapy for GBM. To establish syngeneic models, 10 week-old mice were subcutaneously implanted with murine SB28 or GL261 GBM cells. Treatment with either polyclonal sera to VEGF or Aflibercept failed to reduce tumor load or provide a therapeutic benefit. To next investigate if this model could recapitulate the response obtained patients tumors, formalin fixed paraffin embedded tissue was analyzed for both EMP2 and HIF-2a expression. Both markers were significantly upregulated in Aflibercept treated samples compared to the control.To next investigate if combination treatment could produce a significant reduction in tumor load, animals were treated with a combination treatment with Aflibercept and anti-EMP2 mAb. The combination therapy significantly reduced tumor volume and weight in comparison to control-treated tumors. Combination treatment in SB28 tumors resulted in a two fold reduction in tumor load and 50% reduction in tumor weight. Moreover, tumors showed reduced Ki67 expression. Similarly, treated GL261 tumors produced a 2.3 fold reduction in tumor size and ~2.7 fold reduction in tumor weight. Our results suggest that EMP2 can be a promising new target therapeutic target that can be combined with anti-VEGF treatment to potentially increase overall survival in GBM patients. Citation Format: Brian Aguirre, Mahlet Mekonnen, Riddhi Mehta, Meera Suresh, Anubhav Chandla, Karam Han, Isaac Yang, Madhuri Wadehra. EMP2 is a targetable biomarker in GBM tumors resistant to anti-angiogenic therapies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2508.

Systematic review and pooled analysis of the impact of treatment-induced lymphopenia on survival of glioblastoma patients

Purpose/objective(s)Treatment related lymphopenia is a known toxicity for glioblastoma (GBM) patients and several single-institution studies have linked lymphopenia with poor survival outcomes. We performed a systematic review and pooled analysis to evaluate the association between lymphopenia and overall survival (OS) for GBM patients undergoing chemotherapy and radiation therapy (RT).Materials/methodsFollowing PRISMA guidelines, a systematic literature review of the MEDLINE database and abstracts from ASTRO, ASCO, and SNO annual meetings was conducted. A pooled analysis was performed using inverse variance-weighted random effects to generate a pooled estimate of the hazard ratio of association between lymphopenia and OS.ResultsTen of 104 identified studies met inclusion criteria, representing 1,718 patients. The lymphopenia cutoff value varied (400–1100 cells/uL) and as well as the timing of its onset. Studies were grouped as time-point (i.e., lymphopenia at approximately 2-months post-RT) or time-range (any lymphopenia occurrence from treatment-start to approximately 2-months post-RT. The mean overall pooled incidence of lymphopenia for all studies was 31.8%, and 11.8% vs. 39.9% for time-point vs. time-range studies, respectively. Lymphopenia was associated with increased risk of death, with a pooled HR of 1.78 (95% CI 1.46–2.17, P < 0.00001) for the time-point studies, and a pooled HR of 1.38 (95% CI 1.24–1.55, P < 0.00001) for the time-point studies. There was no significant heterogeneity between studies.ConclusionThese results strengthen observations from previous individual single-institution studies and better defines the magnitude of the association between lymphopenia with OS in GBM patients, highlighting lymphopenia as a poor prognostic factor.

Glioblastoma and Internal Carotid Artery Calcium Score: A Possible Novel Prognostic Partnership?

Purpose: Clinical evidence suggests an association between comorbidities and outcome in patients with glioblastoma (GBM). We hypothesised that the internal carotid artery (ICA) calcium score could represent a promising prognostic biomarker in a competing risk analysis in patients diagnosed with GBM. Methods: We validated the use of the ICA calcium score as a surrogate marker of the coronary calcium score in 32 patients with lung cancer. Subsequently, we assessed the impact of the ICA calcium score on overall survival in GBM patients treated with radio-chemotherapy. Results: We analysed 50 GBM patients. At the univariate analysis, methyl-guanine-methyltransferase gene (MGMT) promoter methylation (p = 0.048), gross total tumour resection (p = 0.017), and calcium score (p = 0.011) were significant prognostic predictors in patients with GBM. These three variables also maintained statistical significance in the multivariate analysis. Conclusions: the ICA calcium score could be a promising prognostic biomarker in GBM patients.

A novel disulfidptosis-related gene signature predicts overall survival of glioblastoma patients.

Aim: The aim of this study was to investigate the prognostic relevance of disulfidptosis-related genes in glioblastoma using bioinformatic analysis in The Cancer Genome Atlas Program-Glioblastoma (TCGA-GBM) database and develop a gene signature model for predicting patient prognosis. Methods: We conducted a bioinformatic analysis using the TCGA-GBM database and employed weighted co-expression network analysis to identify disulfidptosis-related genes. Subsequently, we developed a predictive gene signature model based on these genes to stratify glioblastoma patients into high and low-risk groups. Results: Patients categorized into the high-risk group based on the disulfidptosis-related gene signature exhibited a significantly reduced survival rate in comparison to those in the low-risk group. Functional analysis also revealed notable differences in the immune status between the two risk groups. Conclusion: In conclusion, a new disulfidptosis-related gene signature can be utilised to predict prognosis in GBM.

Interleukin-11/IL-11 Receptor Promotes Glioblastoma Cell Proliferation, Epithelial-Mesenchymal Transition, and Invasion.

Glioblastoma is highly proliferative and invasive. However, the regulatory cytokine networks that promote glioblastoma cell proliferation and invasion into other areas of the brain are not fully defined. In the present study, we define a critical role for the IL-11/IL-11Rα signalling axis in glioblastoma proliferation, epithelial to mesenchymal transition, and invasion. We identified enhanced IL-11/IL-11Rα expression correlated with reduced overall survival in glioblastoma patients using TCGA datasets. Proteomic analysis of glioblastoma cell lines overexpressing IL-11Rα displayed a proteome that favoured enhanced proliferation and invasion. These cells also displayed greater proliferation and migration, while the knockdown of IL-11Rα reversed these tumourigenic characteristics. In addition, these IL-11Rα overexpressing cells displayed enhanced invasion in transwell invasion assays and in 3D spheroid invasion assays, while knockdown of IL-11Rα resulted in reduced invasion. Furthermore, IL-11Rα-overexpressing cells displayed a more mesenchymal-like phenotype compared to parental cells and expressed greater levels of the mesenchymal marker Vimentin. Overall, our study identified that the IL-11/IL-11Rα pathway promotes glioblastoma cell proliferation, EMT, and invasion.

Preoperative epilepsy is an independent predictive factor for overall survival in Glioblastoma patients - a Bi-Center Analysis of 597 patients

Preoperative epilepsy is an independent predictive factor for overall survival in Glioblastoma patients - a Bi-Center Analysis of 597 patients

Syngeneic Mouse Model of Glioblastoma: Intracranial Implantation of GL261 Cells.

Glioblastoma (GBM) is the most aggressive and prevalent primary brain malignancy in adults. Current treatments provide limited benefit, and thus, the median overall survival of GBM patients is only 15months. GBM progression is highly dependent on its ability to evade immune response, so understanding the mechanisms behind GBM-driven immunosuppression seems crucial for designing more efficient therapies. Animal models of GBM constitute a convenient tool in glioma research, and several different approaches have been already developed to model this disease in vivo, including genetic and xenograft models. Here, we describe a murine syngeneic model of glioma which recapitulates many of the key features of human disease, including complex tumor microenvironment. We present an optimized protocol for stereotactic intracranial implantation of GL261 cells into C57BL/6 mice which results in tumor growth in the striatum. This model has been widely used to get insight into glioma biology, as well as in the studies aiming at the development and validation of new therapeutic approaches.

IMMU-08. EOSINOPHILS ARE IMPORTANT MODULATORS OF AN IMMUNE-RESPONSIVE TUMOR-MICROENVIRONMENT IN GLIOBLASTOMA

Abstract Eosinophils, bone marrow-derived granulocytes involved in allergic asthma and autoimmunity, have attracted increasing attention due to their assumed role in effective responses to immune checkpoint blockade in some extracranial tumors. However, the role of this rare type of immune cells in immunologically cold tumors such as glioblastoma (GBM) has not been studied so far. When quantifying immune infiltrates and levels of 30 immune-relevant cytokines in 60 matched pairs of human primary and recurrent GBM, strongest correlations (r= 0.71-0.93) were observed for the eosinophil-associated cytokines Eotaxin and Il-5 as well as for TNFa, IFNg and Il2 which are important cytokines for cytotoxic T cell responses. A combined score of these cytokines (Eo score) turned out to be an independent prognostic marker for improved overall survival of GBM patients. Furthermore, multicolor immunofluorescent staining revealed that Eo score high GBM are significantly higher infiltrated by effector T cells and show a significantly lower infiltration with anti-inflammatory M2-like tumor-associated macrophages / microglia cells (M2-TAM) in recurrent GBM. Flowcytometry analysis of GBM-derived single cell suspensions confirmed a positive correlation of higher eosinophil numbers with higher numbers of tumor-infiltrating T cells, while an inverse relation between eosinophils and monocytes could be demonstrated in the TCGA data set. Spatial transcriptomic data of human GBM confirmed that areas with a higher eosinophil infiltration showed higher numbers of T cells and pro-inflammatory M1-TAM, lower numbers of M2-TAM and a remarkable vessel normalization. Finally, in a newly developed patient-derived GBM organoid model we could corroborate the functional impact of eosinophils on the tumor-microenvironment. An increase of eosinophil numbers in these patient avatars resulted in a significantly decreased number of M2-TAM. Altogether, tumor-infiltrating eosinophils seem to be a novel type of immune-modulator in GBM and may enhance immune responses by shaping the tumor niche from an immunosuppressive to an immunepermissive microenvironment.

NIMG-13. ROBUSTNESS OF PROGNOSTIC STRATIFICATION IN DE NOVO GLIOBLASTOMA PATIENTS ACROSS 22 GEOGRAPHICALLY DISTINCT INSTITUTIONS: INSIGHTS FROM THE RESPOND CONSORTIUM

Abstract PURPOSE Glioblastoma is the most prevalent primary malignant brain tumor in adults, with a median overall survival (OS) of approximately 15 months and only limited advancements in prognostication and survival prediction. This study aims to evaluate an AI-based prognostic stratification model for OS prediction trained on the ReSPOND consortium data and to validate its performance on an independent dataset. METHODS The AI model was trained on a cohort of 2,293 glioblastoma patients from 22 institutions across three continents. For validation, an independent cohort of 78 treatment-naïve patients was used from three institutions. Preoperative structural MRI scans were utilized for feature extraction. Automated segmentation defined three tumor sub-compartments: enhancing, necrotic, and peritumoral T2-FLAIR abnormality. The AI predictor incorporated variables such as patient age, normalized tumor sub-compartment volume, spatial distribution characteristics, and morphologic descriptors. The overall survival predictor index provided a continuous value between 0 and 1 for patient stratification that higher values indicating longer predicted OS. Generalizability was assessed using Leave-One-Cohort-Out-Cross-Validation (LOCOCV) for training data, and the model was subsequently applied to the validation cohort. RESULTS Survival analysis demonstrated a concordance index of 0.64 for LOCOCV training data and 0.59 for the independent validation data, indicating effective prognostic stratification of patients. CONCLUSION Multi-parametric AI assisted image analysis extracts prognostic biomarkers, which correlate with OS in glioblastoma patients. The generalizability of this method was validated using the extensive centralized glioblastoma imaging dataset registry from the ReSPOND consortium and an independent dataset, demonstrating its generalizability across diverse patient populations and acquisition settings. This model holds promise for robust prognostic stratification and prediction in de novo glioblastoma patients.

Switch to generic formulation of temozolomide results in statistically significant increase in grade 3 and 4 bone marrow toxicity in glioma patients in the province of Alberta.

Temozolomide (TMZ) is an oral, systemic chemotherapy used chiefly for treating high-grade glioma. Due to the rising costs of systemic chemotherapy, many jurisdictions have replaced brand name with generic formulations. The aim of this study was to determine whether or not there was difference in the incidence of grade 3 or 4 bone marrow toxicity and median overall survival in patients treated with brand name versus generic TMZ in the province of Alberta, Canada. The province suspended the use of generic TMZ based on preliminary data pointing to excess toxicity. This multicenter, retrospective study included data from patients with newly diagnosed high-grade glioma that received treatment with TMZ in Alberta. Multivariate logistic regression analysis was performed to determine the association between grade 3 or 4 toxicity to generic versus brand name TMZ exposure, ECOG score, and age. Kaplan-Meier survival estimates and log-rank testing were used to determine differences in overall survival between the brand name and generic TMZ cohorts, as well as the cytopenic versus non-cytopenic patients. Furthermore, a screening analysis for grade 3 or 4 bone marrow toxicity was conducted on all de novo glioma patients treated with brand name TMZ after Alberta preemptively stopped generic TMZ. Grade 3 or 4 neutropenia and thrombocytopenia were observed in 15% and 19% of patients treated with generic TMZ (n = 156) as compared to 3% and 5% of patients (n = 100) treated with brand name TMZ-treated patients; P= .003 and .001. A trend toward increased median overall survival in glioblastoma patients treated with generic TMZ (13.7 months) versus brand name (15.8 months, P = .178.) was also observed through meeting statistical significance. Based on these results, the province stopped the use of generic TMZ and reverted to the Merck TMZ. An initial review of all new glioma patients (n = 89) treated with Merck TMZ since the province stopped the generic drug demonstrated 3.4% and 10.1% grade 3 or 4 neutropenia, respectively. The statistically significant difference in toxicity profile has prompted the province of Alberta to replace generic TMZ with brand name TMZ in high-grade glioma patients pending more detailed analysis. Our study provides evidence supporting the importance of conducting prospective studies on long-term safety for generic chemotherapies.

Metformin use is associated with longer survival in glioblastoma patients with MGMT gene silencing.

New treatments are needed to improve the overall survival of patients with glioblastoma Metformin is known for anti-tumorigenic effects in cancers, including breast and pancreas cancers. In this study, we assessed the association between metformin use and overall survival in glioblastoma patients. We retrospectively studied 241 patients who underwent surgery at diagnosis of glioblastoma between 2014 and 2018. Metformin was used for pre-existing type 2 diabetes mellitus or in the prevention or management of glucocorticoid induced hyperglycemia. Kaplan-Meier curves and log-rank p test were used for univariate analysis. Cox-proportional hazards model was used to generate adjusted hazard ratios for multivariate analysis. Metformin use was associated with longer survival in patients with tumors that had a methylated O6-methylguanine DNA methyltransferase gene (MGMT) promoter (484 days 95% CI: 56-911 vs. 394 days 95% CI: 249-538, Log-Rank test: 6.5, p = 0.01). Cox regression analysis shows that metformin associates with lower risk of death at 2 years in patients with glioblastoma containing a methylated MGMT promoter (aHR = 0.497, 95% CI 0.26-0.93, p = 0.028). Our findings suggest a survival benefit with metformin use in patients with glioblastomas having methylation of the MGMT promoter.