Citations

Abstract A new mouse model for the classical subtype of human glioblastoma (GBM) has been bred using Cre-mediated EGFRvIII overexpression and homozygous p19-ARF deletion, the mouse homolog of human p14ARF/CDKN2A, in GFAP expressing cells. Transgenic mice develop intraparenchymal and/or leptomeningeal brain lesions with some spinal cord invasion as early as 1 month old and 95% of mice die by 6 months due to hydrocephalus and/or paralysis. Mice with high grade tumors have worse survival and similar features to human classical GBM such as necrosis, high levels of mitosis and infiltration of tumor cells into normal brain. Immunohistochemical analysis confirms EGFRvIII overexpression and p19-ARF loss in Cre-expressing cells, along with patchy positive GFAP and high proliferation by Ki67. Bulk RNA sequencing reveals GEC3 tumors cluster closely with human classical GBM and have significant upregulation of downstream markers in the JAK/STAT and P13K/AKT pathways. Adherent and neurosphere primary culture of dissociated tumors indicate that tumor cells maintain EGFRvIII expression in culture and generate xenograft tumors by 3 weeks after intracranial injections into NODSCID mice. Xenograft tumors are reminiscent of the primary tumor, with similar histopathological features and immunohistochemical staining. Our spontaneous glioma model is a powerful tool for future studies focused on the role of the immune microenvironment on glioma recurrence and resistance.

Abstract Recurrent or refractory IDH-mutant (mt) gliomas represent a population with significant unmet clinical need. The Notch ligand delta-like 3 (DLL3) is a tumor-associated antigen that is highly and homogeneously expressed in IDH-mt gliomas but absent in normal brain tissue, making it an attractive therapeutic target. Tarlatamab is a half-life extended bispecific T-cell engager that targets DLL3 and CD3 to redirect cytotoxic T cells toward DLL3-expressing tumor cells. Given the specific expression of DLL3 in IDH-mt gliomas and promising activity of tarlatamab in other DLL3-positive tumors, this study investigates the safety, efficacy, and intracranial activity of tarlatamab in this patient population. TARGID is an open-label, phase II trial enrolling adult patients with histologically confirmed IDH1 or IDH2-mt astrocytoma or oligodendroglioma following up to two prior lines of systemic therapies. The study comprises two cohorts. Cohort 1 (n=10) includes patients with resectable disease who will receive up to three cycles of tarlatamab prior to surgery; postoperative continuation is permitted. The primary endpoint for this cohort is the change in CD8+ T-cell infiltration in tumor tissue and blood. Cohort 2 (n=34) includes patients with unresectable disease and uses a Simon’s optimal two-stage design (H0: P ≤ 0.1 versus H1: P ≥ 0.25). In the 1st stage, 13 patients will be accrued. If 2 or more responses are observed, 21 additional patients will be enrolled. Tarlatamab is administered intravenously at 10 mg every two weeks, following a 1 mg priming dose on Cycle 1 Day 1. The primary endpoint is objective response rate by RANO 2.0. Exploratory endpoints include DLL3 expression, circulating biomarkers, and immune correlatives. The trial is currently in activation, with first patient enrollment anticipated in Q3 2025. The study is supported by the provision of study drug from Amgen as an investigator-initiated trial.

Abstract The brain avidly consumes glucose to fuel neurophysiology. Cancers of the brain, such as glioblastoma (GBM), relinquish physiological integrity and gain the ability to proliferate and invade healthy tissue. How brain cancers rewire glucose utilization to drive aggressive growth remains elusive. Here, we infused 13C-labeled glucose into patients and mice with brain cancer, coupled with quantitative metabolic flux analysis, to map the fates of glucose-derived carbon in tumor vs. cortex. Through the first direct and comprehensive measurements of carbon and nitrogen labeling in both cortex and glioma tissues, we uncover profound metabolic transformations. In human cortex, glucose carbons fuel essential physiologic processes including TCA cycle oxidation and neurotransmitter synthesis. Conversely, gliomas downregulate these processes and scavenge alternative carbon sources such as amino acids from the environment, repurposing glucose-derived carbons to generate molecules needed for proliferation and invasion. Targeting this metabolic rewiring in mice through dietary amino acid modulation selectively alters GBM metabolism, slows tumor growth, and augments the efficacy of standard-of-care treatments. These findings illuminate how aggressive brain tumors exploit glucose to suppress normal physiological activity in favor of malignant expansion and offer potential therapeutic strategies to enhance treatment outcomes.

Abstract High-grade glioma (HGG) continues to have a dismal prognosis owing in part to its heterogeneous and invasive nature both within and between patients. The most aggressive form of high-grade glioma, called glioblastoma, portends a median survival of around 15 months. Like many cancers, high-grade glioma rewires metabolism towards its own benefit, shifting away from the typical reliance of brain tissue on glucose towards other sources such as fatty acids and acetate. Using a cohort of image-localized high-grade glioma biopsies collected from diverse imageable regions with associated transcriptomics (58 patients, 202 biopsies), we are able to assess the spatial transcriptomic landscape of HGG. We have previously shown that the transcriptome of HGG can be characterized into a continuous transition between states, and we have shown that the cellular ecosystem follows a similar pattern, using a combination of trajectory inference and cellular deconvolution. These patterns are strongly associated with the non-enhancing and contrast-enhancing regions of the tumors, which are typically considered for treatment planning and progression assessment. Here, we applied differential expression of hallmark pathways to determine how metabolism factors into this paradigm. As expected, we find overall higher levels of metabolism-associated pathway expression in the contrast enhancing regions compared to the non-enhancing regions. Interestingly, we found metabolic expression differs between the ecologies associated with transcriptional subtypes of high-grade glioma. For example, fatty acid (p=0.003), xenobiotic (p<0.0001) and heme (p<0.0001) metabolism pathways were significantly upregulated for mesenchymal tumor samples, while significantly downregulated for proliferative tumor samples (p=0.02, p<0.0001, p<0.0001, respectively). As we continue to further understand the complex spatial and temporally heterogeneous landscape of these aggressive tumors, it is important to consider the metabolites on which they depend, to better inform prognosis and develop new treatments.

Abstract Glioblastoma (GBM), the most common malignant primary brain tumor in adults, has a median survival of 15 months and 5-year survival rate of only 6.9%. Standard of care, including radiation and chemotherapy, can induce cellular senescence in the brain. The senescence-associated secretory phenotype (SASP) significantly affects glioma microenvironment as these secreted factors exhibit both anti-and pro-tumorigenic effects. However, it is currently unknown whether senescence in the surrounding GBM microenvironment could be beneficial or detrimental to tumor outcomes. Using cell-specific proteomics, we identified upregulation of cathepsin B (CTSB) expression in patient-derived brain tumor initiating cells (BTICs) co-cultured with human fetal neural progenitor cells (NPCs). In matched patient tumor biopsies, sequencing of lateral ventricle (LV)-proximal regions revealed increased CTSB expression compared to LV-distal counterparts. Remarkably, LV-proximal GBMs induced a senescent phenotype and reduced differentiation in subventricular zone (SVZ) NPCs through CTSB secretion. We hypothesize that senescent NPCs in the SVZ contribute to a pro-tumorigenic microenvironment that promotes tumor aggressiveness in LV-proximal GBM. To model this in vitro, senescence was induced in NPCs using recombinant CTSB (100 nM) and hydrogen peroxide (250 µM, 2 hours). Treated NPCs showed increased β-galactosidase activity and increased expression of SASP factors IL-1α, IL-6, and CTSB. Senescent NPCs significantly increased BTIC migration and proliferation (p<0.05) both in co-culture and through conditioned media, suggesting this effect may be mediated by soluble factors. These findings support the hypothesis that senescent NPCs promote BTIC malignancy in LV-proximal GBM and identify CTSB as a potential mediator of this interaction.

Abstract INTRODUCTION Glioblastoma (GBM) contains metabolically distinct cell lineages: treatment-sensitive cells (TSCs) dependent on glycolysis and treatment-resistant persister cells (TRPCs) reliant on lipid metabolism. Our integrative systems biology approach, combining spatial multi-omics and targeted analyses, uncovers lipid acquisition in TRPCs as a pivotal driver of GBM progression which is supported by a retrospective study of statin-treated patients, providing clinical evidence for the therapeutic potential of targeting lipid metabolism in GBM patients stratified based on high TRPC signatures. METHODS We applied spatial transcriptomics and proteomics combined with 3D reconstruction of the tumor microenvironment to map TRPC- and TSC-enriched regions. Immunohistochemically stained tissues were analyzed using CellProfiler and our custom SNAQ algorithm for single-cell neighborhood analysis. Lipid transfer from Tumor-Associated Myeloid Cells (TAMCs) to TRPCs was tracked via flow cytometry, holotomography, and time-lapse imaging. Genetic and pharmacological targeting of CCR2, CSF1R, and FABP3 was performed in vitro and in vivo. Finally, a retrospective analysis of 4,085 GBM patients assessed the impact of statin treatment in relation to TRPC signatures. RESULTS TRPCs exploit recruited TAMCs to acquire lipids, supporting their survival and immune evasion. These interactions are mediated by CCL2/7–CCR2 and CSF1–CSF1R signaling. Disruption of TRPC-TAM lipid homeostasis significantly remodeled the immune microenvironment, reduced tumor growth, and extended survival in preclinical models. Patients with high TRPC signatures typically had poor outcomes; however, retrospective analysis revealed that statin treatment was associated with improved survival in this subgroup. These findings position lipid trafficking as a metabolic vulnerability in GBM and highlight the therapeutic relevance of targeting TRPC–TAMC interactions. CONCLUSION Our study reveals lipid trafficking to TRPCs as a key mechanism driving GBM progression. Targeting TAMC-mediated lipid transfer disrupts immune suppression and tumor growth. Transcriptomic profiling may guide patient stratification, identifying those likely to benefit from lipid metabolism-targeted therapies such as statins.

Abstract INTRODUCTION Hydrocephalus in pediatric patients is commonly treated with endoscopic third ventriculostomy (ETV) or ventriculoperitoneal shunting (VPS). When primary ETV fails, clinicians must decide between repeat ETV (Re-ETV) and VPS placement. However, the optimal secondary intervention remains debated. Objective: To compare the efficacy and outcomes of Re-ETV versus VPS placement following failed primary ETV in pediatric hydrocephalus. METHODS We conducted a systematic review following PRISMA guidelines. Searches of PubMed, Embase, and the Cochrane Library identified English-language studies (2001–2023) reporting on Re-ETV or VPS after failed primary ETV in patients aged 0–18 years. Comparative studies, including randomized controlled trials, cohort studies, and prospective designs were eligible. Two independent reviewers screened titles, abstracts, and full texts; extracted data on sample size, intervention rates, failure rates, and complications; and assessed study quality using RoB 2.0 and CASP tools. Pooled descriptive statistics and odds ratios (OR) were calculated for secondary intervention failure. RESULTS Nine studies (n = 663) met inclusion criteria. Re-ETV was performed in 220 patients (33.2%) and VPS in 443 (66.8%). Primary ETV failure rates ranged from 16.6% to 60.9% (mean 40.6%). Re-ETV exhibited a pooled failure rate of 74.98%, whereas VPS failure was 22.26% (OR 4.86; 95% CI 3.21–7.38; p < 0.05). Hemorrhagic etiology during primary ETV significantly favored VPS over Re-ETV (p < 0.05). Time to secondary failure averaged 15.8 ± 21.7 months, with broad inter-study variability. CONCLUSION VPS placement demonstrates a substantially lower failure rate than Re-ETV as a secondary intervention after primary ETV failure in pediatric hydrocephalus. Nevertheless, variability in patient age, etiology, and follow-up underscores the necessity of individualized decision-making. Prospective trials with standardized outcome measures are warranted to refine secondary treatment guidelines.

Abstract Glioblastoma (GBM) and Alzheimer’s disease (AD) are devastating, age associated disorders with no cure. Epidemiologic data has established an inverse comorbidity between AD and cancer, including GBM, with up to a 50% reduction of cancer incidence in AD patients. While the underlying biology remains unclear, myeloid cells, which are central players in both neurodegeneration and tumor immunity, may serve as a mechanistic link. We hypothesize that myeloid cells activated by pre-existing AD pathology suppress tumor growth more effectively than homeostatic microglia. In this study, age-matched APPNL-G-F/MAPT double knock-in (henceforth “AD”) and wildtype (WT) mice received orthotopic xenografts of syngeneic GBM cell lines (GL261, SB28) (n=15/sex/genotype). We observed a significant survival difference, with AD mice living an average of 20% longer than WT mice (p<0.0001). In vivo luciferase imaging revealed impaired engraftment of tumor cells in AD mice compared to WT a week post-engraftment (p<0.05). At the microscopic level, tumors in AD mice were found to have nearly 2-fold the amount of tumor-infiltrating myeloid cells (p<0.01), with the proportion of anti-tumoral “activated” myeloid cells also being greater (p<0.05). Tumors in AD mice were found to have markedly higher immune infiltrate at the tumor rim and margin (p<0.001). We also observed striking astrogliosis (GFAP+) and microgliosis (P2RY12+) in both the tumor rim (p<0.05) and margin (p<0.01) in AD animals. This robust glial response was significantly higher in AD mice bearing tumor compared to both WT mice bearing tumor and sham AD mice. Lastly, we utilized a luciferase stain to visualize tumor cells that invaded beyond the bulk tumor. We found that both the quantity (p<0.01) and invasion distance of tumor cells (p<0.05) was lower in AD mice. We demonstrate that an AD-induced inflammatory microenvironment antagonizes glioma growth, providing a foundation for novel GBM treatment strategies that potentially exploit these immune signals.

Abstract BACKGROUND Gaseous hydrogen sulfide (H2S), a by-product of cysteine metabolism, inhibits cancer cell behavior and growth in glioblastoma (GBM) models. H2S production capacity (HPC) is decreased in human GBM specimens compared to non-tumor controls. Thus, boosting HPC is a novel strategy for GBM treatment. Suppression of thyroid hormone signaling increases production of H2S. Hypothesis: methimazole-induced hypothyroidism will increase tumor HPC to enhance chemotherapy efficacy in GBM. GOAL Proof of concept that methimazole, by reducing thyroid hormone signaling, can increase HPC in patients with recurrent/progressive GBM (rGBM). PRIMARY ENDPOINTS 10% increase in HPC and a 1.5-fold increase in peripheral blood sulfhydration signaling. METHODS This window of opportunity trial evaluates safety, HPC in plasma and tumor, and efficacy of methimazole + chemotherapy in patients with rGBM. rGBM patients planned for a resection begin methimazole 15 mg/d 5-7 days pre-op with investigator’s choice chemotherapy added 10-28 days post-op. Patients receive combination until progression. Pre- and post-op plasma and resected tumor tissue are assayed for HPC and proteins relevant to H2S production. Key eligibility: rGBM for whom a clinically-indicated resection is planned; normal thyroid function with no history of thyroid dysfunction. Patients may have received unlimited prior regimens including bevacizumab. RESULTS To date 15 patients (8 male), median age 56 years, enrolled. The trial was amended to increase methimazole to 25 mg/d; 3 patients have received this dose. Median TSH rose from 1.3 mU/ml to 20.5 at cycle 6. Free T3 and T4 did not fall significantly. Median plasma HPC rose 3-fold while tumor HPC did not rise significantly. No treatment-related grade 3-5 toxicities. Efficacy: PFS6 – 15% and OS12 – 21%. CONCLUSIONS Induction of subclinical hypothyroidism is feasible and safe in rGBM with significant increases in plasma but not tumor HPC. Further tumor correlative data for the dose-escalated methimazole will be presented.

Abstract Triggering receptor expressed on myeloid cells 2 (TREM2) is a critical modulator of phagocytosis, inflammation, and survival for microglia and other macrophages. In neurodegenerative disorders, microglia expressing TREM2 play a protective role at distinct phases of disease progression, enabling uptake of toxic protein aggregates and dead neurons. TREM2 is also highly expressed on tumor-associated macrophages in a variety of cancers, promoting an immunosuppressive microenvironment. We and others have previously investigated the role of TREM2 in gliomas with confounding results, suggesting TREM2 could be pro-tumorigenic or anti-tumorigenic depending on experimental context (Peshoff, et al. Neuro Oncol. and Zheng, et al. Neuro Oncol.) In this study, we aim to resolve these findings by investigating the role of TREM2 across progression of gliomas with unique genetic drivers using immunocompetent mouse models. We employ syngeneic glioma stem cell lines generated via retroviral vectors expressing a dominant negative p53 along with amplification of human PDGFB or oncogenic HRAS G12V to model proneural and mesenchymal glioblastomas, respectfully. In contrast to our previous results demonstrating enhanced GL261 and CT2A growth in Trem2-/- mice, we demonstrate that Trem2 deficiency results in decreased tumor volume and improved survival when mice are challenged with Ras-driven, but not PDGFB-driven, gliomas. Furthermore, Trem2-/- mice display a more immunostimulatory microenvironment with increased T cell infiltration to mesenchymal-like tumors. We employ an in vitro co-culture system of primary mouse microglia with glioma stem cells to understand how microglia sense and respond to different genetic subtypes. We find that TREM2-mediated processes including microglial phagocytosis, chemotaxis, and survival are impacted by glioma genetic drivers. Together, these results indicate discrepancies in the literature regarding the function of TREM2 in gliomas may be explained by tumor genetics behind the cell lines used, which can provide a framework for understanding subtypes of gliomas that could respond to TREM2-modulating therapy.