Citations

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.

Abstract The 5-year survival rate for metastatic melanoma (MM) is 35% with rates increasing to ~50% with immune checkpoint blockade (ICB) treatment. Unfortunately, melanoma brain metastases (MBM) develop in nearly half of MM patients and often relapse rapidly following ICB treatment. MBM resistance to ICB can be attributed to tumor-associated macrophages (TAM). Transcriptional profiling of MM revealed that TAMs possess a lipidated phenotype suggesting that aberrant lipogenic processes confer ICB resistance. Stearoyl-CoA desaturase (SCD) is a lipogenic enzyme that is overexpressed in MM and may cause TAM lipidation. SCD serves as an attractive target for inhibition and combination with ICB for treating MBM. We hypothesize that SCD overexpression produces lipid-rich tumor cells that trigger a phenotypic switch towards immunosuppressive lipid-laden macrophages (LL-Mø). Clinical correlation analysis was conducted to assess SCD expression with ICB response. scRNA-seq data of MBM were analyzed to assess TAMs exhibiting lipidated phenotype. Phagocytosis and lipid transfer was assessed via macrophage and melanoma co-culture using time-lapse microscopy. In-silico modeling and LC-MS/MS was performed to assess blood brain barrier (BBB) penetrance of two small molecule inhibitors of SCD (SCDi): MTI-301 and MF-438. Clinical correlation analysis of MM patients revealed high SCD expression associated with decreased survival of patients treated with ICB. scRNA-seq analysis of MBM revealed upregulation of de novo lipogenesis and cholesterol uptake transcripts within TAM populations. Time-lapse co-culture studies reveal rapid lipid accumulation in macrophages. In-silico modeling predicted SCDi BBB penetration and was corroborated by LC-MS/MS. MBM are notoriously difficult to treat due to poor drug penetrance into CNS and unique microenvironment. We demonstrate that macrophages reprogram towards immunosuppressive LL-Mø, which can be exploited for anti-tumor targeting. The potential for SCDi to synergize with ICB in MBM may improve patient outcomes. MTI-301 is approved for first-in-human clinical trial starting end of 2025.

Abstract Spontaneously arising canine high-grade gliomas (cHGG) offer a clinically relevant model for human glioblastoma, sharing conserved histopathological, genetic, and immunological traits. We established two cHGG cell lines and two canine adipose-derived mesenchymal stem cell (cAMSC) lines, and immune-competent 3D cHGG organoid models. Immunoblotting of cHGG cell lines showed that these models exhibit hallmark GBM features including SOX2, Nestin, GFAP, and activation of PI3K/AKT and p53 pathways. Given the established cytotoxic and differentiation-inducing effects of BMP4 in human GBM cell lines, we evaluated whether our canine glioma models recapitulate these responses to assess their translational relevance. BMP4 treatment of cHGG cells induced significant cytotoxicity and reduced migration, accompanied by downregulation of SOX2 and Nestin, upregulation of GFAP, and suppression of CDK6 and phospho-AKT—hallmarks of reduced stemness and astrocytic differentiation. In human-derived GBM cells, BMP4 enhanced radiosensitivity, likely via differentiation and depletion of therapy-resistant stem-like populations. Our cHGG models mirrored these molecular responses, suggesting a conserved BMP4 signaling axis in canine glioma. Quantitative phase imaging showed that BMP4 treatment was non-toxic to cAMSCs and did not impair their migration, supporting the feasibility of engineering cAMSC-BMP4 for therapeutic delivery. Observed molecular traits in canine and human gliomas—including mutually exclusive mutations in PDGFRA and PIK3CA, and shared expression of TP53, PTEN, p21, Rb1, mTOR, and MAPK—underscore the translational relevance of the cHGG model. High-content imaging further confirmed expression of p-AKT, p53, MDM2, and CD44 in cHGG lines, reinforcing activation of conserved gliomagenic pathways. To complement these findings, we developed a cHGG 3D organoids from freshly resected tumors, that recapitulate tumor heterogeneity with co-localized GFAP+/Nestin+ glioma cells, CD3+ infiltrating T cells, macrophages and cleaved caspase-3+ apoptotic cells, indicating active immune surveillance and ongoing programmed cell death. Our results support canine GBM model as a platform to assess glioma biology, cell therapy, and modeling immune engagement in a species-relevant, physiologically intact environment for streamlined translation of therapeutics to human clinical trials.

Abstract Glioblastoma (GBM) is the most common and aggressive primary brain tumor in adults, with a dismal 5-year survival rate of ~6.5%. Vasogenic cerebral edema is a severe complication that occurs in the majority of GBM patients, leading to a significant increase in intracranial pressure, neurological deficits, and increased mortality rates. GBM-associated edema is almost exclusively managed by the corticosteroid dexamethasone, the use of which is associated with immunosuppression and interference with radiation therapy. While there is considerable research on edema formation, little is known about how edema resolution occurs in GBM, particularly in response to dexamethasone or other anti-edema therapies. This gap in understanding highlights the need for new approaches to treat edema effectively. The water channel aquaporin-4 (AQP4), a key player in the brain’s water homeostasis, is upregulated in GBM compared to the normal brain. To investigate the role of AQP4 in GBM-associated edema, we used the RCAS/tv-a system to generate de novo GBM with different driver mutations in Aqp4 knockout (KO) and wild-type (WT) mice. Our results indicated that Aqp4 KO tumor-bearing mice had shortened survival and increased edema content. Additionally, Aqp4 loss decreased astrocyte coverage specifically in the tumor core but not the tumor periphery. Our single cell RNA-seq data suggested that Aqp4 loss led to an astrocytic shift towards a less reactive, progenitor-like state, while also decreasing the myeloid and CD8+ T cell population in the tumor microenvironment. Interestingly, tumor-bearing mice treated with anti-VEGFA antibody, which has anti-edema properties, showed increased expression of Aqp4 and reduced vessel leakage. This suggests that AQP4 plays a critical role in mediating the effects of anti-VEGFA therapy. Overall, this study highlights the important role of AQP4 in the resolution of edema, while also revealing its additional effects on astrocyte activation and the immune microenvironment in GBM.

Abstract Glioblastoma is an aggressive brain cancer with poor prognosis. Recent evidence implicates metabolic reprogramming, including the hexosamine biosynthetic pathway (HBP) and pentose phosphate pathway (PPP), as critical for tumor survival, therapy resistance, and progression. HBP inhibition with a proprietary small molecule (G2Bz) reduced stemness and migration and increased apoptosis of GBM in vitro. HBP inhibition was concomitant with an accumulation of metabolites in the Pentose Phosphate Pathway (PPP). Therefore, we further inhibited HBP with G2Bz and/or PPP with 6-aminonicotinamide (6-AN) in primary patient-derived GBM lines and evaluated additive or synergistic effects. Ultrastructural and functional changes were examined by electron microscopy (EM), high content imaging of endoplasmic reticulum (ER) and lipid droplets (LD), extracellular-flux analysis, and lipid profiling. Synergism was validated in an orthotopic model receiving lipoparticle-encapsulated G2Bz via intranasal delivery and/or intraperitoneal 6-AN; tumor burden was monitored via bioluminescence. Dual inhibition of HBP/PPP revealed additive or synergistic anti-proliferative effect. EM displayed severe ultrastructural cell damage with mitochondrial disorganization, ER dilation, and cytoskeletal remodeling. These changes coincided with increased ROS generation and reduced spare respiratory capacity suggesting higher sensitivity and lower ability to fight stress. Reduced ER–mitochondria contacts accompanied by increased expression of BiP and ER expansion suggest an unfolded protein response. Loss of LDs were associated with downregulation of lipid biosynthesis regulator SREBF1 and an increase in free fatty acids with a rise in lipid peroxidation. Reduced mitochondria–LD contacts correlate with lower endogenous fatty acid oxidation and a shift to exogenous fatty acid utilization. Dual inhibition in-vivo, suppressed tumor growth compared to control. These findings support that dual inhibition of HBP/PPP synergistically disrupts tumor metabolism, promoting organelle disorganization and lipid remodeling and highlight metabolic co-targeting as a strategy to impair GBM metabolism.

Abstract BACKGROUND Awake craniotomy with speech mapping remains a gold standard for achieving maximal safe resection of diffuse gliomas located in eloquent cortex. Significant practice variability exists with regards to patient selection, speech mapping paradigms, aggressiveness of resection, and use of other adjuncts. We report our experience with speech mapping procedures for patients with diffuse gliomas, comparing cases performed with and without intraoperative MRI. METHODS A single-surgeon retrospective review of 148 consecutive awake craniotomy procedures, from 2008-2024, was performed. We recorded baseline patient characteristics, speech mapping findings, post-operative course, and volumetric extents of resection. Multivariate regression analyses were performed for factors predictive of permanent aphasia and residual tumor volume. RESULTS Speech mapping was performed in 95% of cases, with positive speech areas found in 49% of cases. Intraoperative MRI cases (75% of total) had significantly greater extent of resection (87.4% vs. 78.6%, p=0.03) despite equivalent pre-operative volumes. Post-operative new/worsened aphasia was 15% for mild and 5% for moderate symptoms, and this was associated with reduced rates of return to work (54% vs 78%, p=0.04). Predictors of recovery from aphasia were extent of resection (OR 1.1, p=0.006) and 90-day disease progression (OR 0.06, p=0.04). Predictors of residual tumor volume were pre-operative tumor volume (β 0.3, p<0.001), identification of after-discharge potentials during speech mapping (β -9.7, p<0.001), and pre-operative functional status (β -0.3, p=0.02). Overall survival was impacted by presence of contrast enhancement (p=0.0002), tissue diagnosis (p<0.0001), and WHO grade (p<0.0001). CONCLUSIONS Awake craniotomy with speech mapping remains a valuable strategy for achieving maximal safe resection of diffuse gliomas, with the majority of patients returning to baseline level of functioning. New/worsened aphasia is the biggest risk of surgery, which significantly impacts patient quality of life. Intraoperative MRI can be considered as an adjunctive tool for awake speech mapping during glioma surgery.

Abstract BACKGROUND While most meningiomas are classified as low-grade tumors with indolent behavior, a subset is characterized by a more aggressive clinical course and patients undergo repeated resections and courses of radiation. Once these therapies fail, prognosis is poor and progression-free survival (PFS) rates at 6 months (PFS-6) are estimated to only be 43.6% for WHO grade 1 and 38% for WHO grade 2/3 meningiomas. Effective medical therapies are limited. Somatostatin receptor 2 (SSTR2) is expressed in a majority of meningiomas and represents a suitable treatment target. [177Lu]Lu-DOTA-TATE (177Lu-Dotatate) is an SSTR2-targeted radioligand therapy, established as standard of care in the treatment of certain neuroendocrine tumors. Two ongoing non-randomized studies of 177Lu-Dotatate in meningiomas have reported encouraging efficacy compared to historical benchmarks. METHODS/STUDY DESIGN The MOMENTUM-1 study (RTOG 3523, NCT#06955169) is a multicenter, randomized, open-label study of 177Lu-Dotatate in adult patients with progressive intracranial WHO grade 1-3 meningiomas. Up to 130 eligible subjects are randomized in a 2:1 fashion to 177Lu-Dotatate at 7.4 GBq (200 mCi) every 4 weeks for 4 (+2 optional) doses or standard of care (SOC) medical therapy as defined by the protocol and deemed appropriate by the local investigator. Treatment responses are assessed by gadolinium-enhanced MRI brain and [68Ga]Ga-DOTA-TATE (68Ga-Dotatate) PET imaging. At time of progression, cross-over from the SOC to the interventional treatment arm is allowed. The primary endpoint is PFS. Secondary endpoints include PFS-6, OS-12, OS, response assessments (ORR, DCR), safety/tolerability, and patient-reported outcomes. RESULTS/CONCLUSION MOMENTUM-1 is a multicenter, randomized, open-label, phase II study of 177Lu-Dotatate in adult patients with progressive WHO grade 1-3 meningioma. This clinical trial is expected to start enrolling patients in the United States in the third quarter of 2025. Details on study design, eligibility criteria for subject enrollment and study site eligibility criteria will be presented.

Abstract INTRODUCTION Preserving language during tumor resection is critical but challenged by the time-intensive, complex nature of direct electrical stimulation (DES). High-gamma electrocorticography (ECoG) captures real-time, task-induced cortical responses, yet its spatiotemporal concordance with DES across language tasks remains underexplored. OBJECTIVE To evaluate how early and late high-gamma ECoG responses align with DES across auditory, object, action, and descriptive naming tasks. METHODS Seventeen patients (14 gliomas, 3 metastases) underwent awake craniotomy. ECoG was recorded, and bipolar DES was applied on the same subdural grid across the four tasks using adjacent contacts. Early (100–200 ms) and late (>200 ms) high-gamma activity (30–150 Hz) and DES-positive sites were co-registered with a standard MNI-152 brain. The spatial overlap was quantified using Dice-Sørensen (D-S) coefficients with accuracy assessed by ECoG–DES contact proximity (exact/adjacent, <1 cm) across tumor, peritumoral (<2 cm), and whole-grid ROIs. Patient language outcomes were determined from longitudinal neurologic exams. RESULTS DES-positive sites were identified in 15/17 (88%) patients, primarily during auditory and action naming. Auditory naming elicited gamma activity in all patients, with early and late responses, reflecting sensory and extended semantic processes, observed in 10/17(59%) cases, showing strong concordance with DES (early: D-S= 0.63, 95% CI: 0.51–0.74; early + late: D-S = 0.66, 95% CI: 0.54–0.77). Non-auditory tasks showed predominantly late gamma responses, with modest DES overlap (object: D-S= 0.34; action: D-S= 0.42; descriptive: D-S= 0.37) suggesting border distributed cortical networks. Accuracy in all tasks ranged from 76–95% within the whole grid; auditory naming achieved 83% sensitivity and 82% specificity in peritumoral ROI. At 6 months, 14/17 (82%) patients had no speech deficits; 8/9 with preoperative deficits improved while 2 had a new deficit. CONCLUSION Gamma activity during auditory naming reliably predicts DES-defined language eloquence for safe maximal resection of brain tumors.