Michaelides, Loizos

Gliomas are diffusely infiltrative, requiring accurate and sensitive diagnostic tools during surgical resection. Mutations in isocitrate dehydrogenase enzyme (IDH) alter its normal activity and result in accumulation of a unique oncometabolite, 2-hydroxyglutarate (2HG), in tumor cells. However, IDH-wild-type (IDH-wt) gliomas are more common and typically more aggressive. Here, 86 human brain samples were analyzed by syringe touch spray mass spectrometry to evaluate molecular alterations in gliomas. Tandem mass spectrometry (MS/MS) experiments were performed to minimize isobaric and isomeric interferences, and a ratiometric approach (using only signals for endogenous compounds) was employed to improve reliability of the measurements. Multiple ratios for pairs of metabolite signal intensities were found to differentiate tumor samples from nontumor tissue and they stratified glioma subtypes by IDH mutation status and by tumor grade, with several ratios showing 100% agreement with independent clinical assignments ( P < 0.0001, Mann–Whitney U test). Increased carnitine relative abundances were found across all glioma subtypes. Importantly, α-aminoadipate was significantly elevated in grade 4 glioma, which may correlate with increased tumor malignancy. Grade 3 gliomas showed markedly higher 2HG abundance than grade 4 samples. In addition, a selection of ratios showed a linear trend with varying tumor cell percentage. Overall, the multiple metabolic ratio alterations indicate a high degree of heterogeneity among glioma subtypes. Furthermore, there are metabolites that can differentiate glioma from nontumor tissue and this measurement can be made by a simple ratiometric method which has potential to be used intraoperatively for margin assessment without diverging from standard of care.

Abstract Glioblastoma (GBM) remains the most lethal primary brain cancer due to its remarkable metabolic plasticity and therapeutic resistance. Here, we identify cholesterol dependency as a therapeutically exploitable vulnerability in GBM using two FDA-approved drugs: the H1 histamine antagonist clemastine and the retinoid X receptor agonist bexarotene. Combined treatment induces potent synergistic anti-tumor activity across patient-derived glioma models, suppressing proliferation, stemness, and survival at sub-IC50 concentrations. Mechanistically, this therapy disrupts cholesterol biosynthesis, transport, and homeostasis, triggering endoplasmic reticulum stress and activation of the unfolded protein response, ultimately leading to autophagy and apoptotic cell death. Orthotopic patient-derived glioma models recapitulate these mechanisms in vivo, where local intracranial administration significantly reduces tumor progression and prolongs survival using fourfold lower doses than systemic intraperitoneal delivery. Single-cell RNA sequencing revealed activation of regeneration and plasticity programs, accompanied by immune microenvironment remodeling and enhanced inflammatory signaling. Importantly, syngeneic models preserved immune cell composition, supporting future integration with immunotherapeutic strategies. Together, these findings establish cholesterol dysregulation–induced metabolic collapse as a promising therapeutic approach for GBM.

Abstract Glioma stem cells (GSCs) are considered a major driver of glioblastoma (GBM) progression and are highly resistant to standard cytotoxic treatments. BMP4 has been shown to promote GSC differentiation, enhance radiosensitivity, slow tumor growth, and extend survival in animal models. Despite this promise, BMP4 has yet to achieve clinical impact, owing largely to heterogeneous and nonlinear responses across preclinical experimental systems. To elucidate how BMP4 could function as an effective targeted differentiation therapy in GBM, we develop a mathematical model that describes the growth of a GBM tumor via a hierarchy of GSCs, progenitor and terminally differentiated cells. We parameterize our model using new radiotherapy and proliferation assay data (with and without BMP4 exposure) from twelve patient-derived GSC lines. This integration of model and data allows us, for the first time, to quantitatively capture patient-specific heterogeneity in BMP4 sensitivity. We perform global sensitivity analysis on the model, identifying proliferation rate and GSC self-renewal sensitivity as key determinants of BMP4 efficacy. These parameters act as model-derived biomarkers that distinguish BMP4-responsive tumors from non-responsive ones. In an in silico analysis across a broad cohort of virtual patients, we find that continuous BMP4 delivery from surgical resection through radiotherapy consistently outperforms a single-dose strategy. Virtual clinical trials further show that, without stratification using these model-derived biomarkers, BMP4 yields little observable therapeutic benefit. In contrast, selecting patients with more proliferative, BMP4-responsive GSCs markedly increases the likelihood of observing a significant treatment effect. Citation Format: Nicholas Harbour, Lee Curtin, Loizos Michaelides, Matthew E. Hubbard, Pamela Jackson, Vinitha Rani, Rajappa Kenchappa, Virginea Farias, Anna Carrano, Markus Owen, Alfredo Quinones-Hinojosa, Kristin Swanson. Virtual clinical trials of BMP4 differentiation therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 6831.

Background/Objectives: Postoperative opioid exposure after lumbar fusion remains a key clinical concern. Understanding which perioperative factors are associated with lower postoperative opioid use may help optimize recovery after minimally invasive (MIS) transforaminal lumbar interbody fusion (TLIF). This study aimed to determine if patients undergoing MIS-TLIF under spinal anesthesia (SA) showed lower postoperative opioid use compared to those undergoing MIS-TLIF under general anesthesia (GA). Methods: We retrospectively studied all adult patients (>18 years) undergoing 1- and contiguous 2-level MIS-TLIFs performed by a single surgeon. Patients undergoing the procedure under GA were compared to those undergoing the procedure under SA. Postoperative oral opioid use, up to 3 months post discharge, was collected. A 1:1 propensity score matching (PSM) protocol was implemented. Each outcome variable was initially assessed using univariate regression. Predictor variables with a p-value < 0.2 were included in the multivariate regression model. This was a retrospective, non-randomized study, and residual confounding cannot be excluded despite PSM. Results: The matched groups (n = 50 in each group) did not differ significantly depending on demographics or levels fused. Before regression, mean number of postoperative opioid prescriptions (p = 0.03), mean total operating room (OR) time in minutes (p < 0.01), and median length of stay (LOS) in days (p = 0.03) were significantly different. Multivariate regression showed that the GA group received 216.5 more total morphine milligram equivalents than the SA group (95% CI = 0.7–432.2, p = 0.049). The days of opioid use were higher in the GA group by 3.8 days (95% CI = 0.5 to 7.1, p = 0.025). On multivariate regression, LOS in hours was greater in the GA group by 14.1 h (p = 0.042). Conclusions: SA is an effective anesthetic modality for spinal surgery with the advantages of reduced postoperative opioid use, reduced OR time, and shorter LOS compared to GA.

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 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 Glioblastoma (GBM) is the most common malignant tumor of the CNS, accounting for 80% of brain tumors. Recent advances in gene editing and immunology have led to the development of chimeric antigen receptors (CARs), including CARs incorporating chlorotoxin (CLTX) receptor domains for GBM targeting. While CAR-engineered neutrophils have shown promise, their systemic administration can induce severe off-target effects. Extracellular vesicles (EVs), secreted by these cells, retain properties of their parent cells—including CAR expression and tumor-lytic activity—yet their potential has not been explored in CAR Neutrophils. To address this, CAR-CLTX DNA was inserted into the AAV1 safe harbor locus of induced pluripotent stem cells, which were subsequently differentiated into neutrophils. Conditioned media were collected during differentiation and processed using extraPEG-based EV isolation. EVs were quantified via nanoparticle tracking analysis, electron microscopy, and western blotting. Proteomic and microRNA (miRNA) profiling of EV cargo was conducted at days 12 and 21 of differentiation. Cytotoxic effects of EVs were assessed in U87MG and LN229 glioblastoma cells in 2D culture, 3D organoids, and in vivo models. EVs were secreted in high quantities within the 100–200 nm size range, expressed canonical exosomal markers, and exhibited characteristic morphology. Proteomic analysis identified neutrophil-associated proteins involved in migration, chemotaxis, and degranulation. miRNA sequencing revealed high levels of tumor-suppressive miRNAs (e.g., miR-182) implicated in apoptotic signaling, T cell receptor pathways, cytokine-cytokine receptor interactions, Jak-STAT, Hedgehog, and NK cell-mediated cytotoxicity. EV uptake by glioma cells was demonstrated in vitro. Cytotoxic effects of CAR Neutrophil EVs were observed across glioblastoma cell lines, organoids, and in vivo. These findings demonstrate that CAR Neutrophil-derived EVs carry anti-tumor protein and miRNA cargo, are efficiently taken up by GBM cells, and mediate glioma cell cytotoxicity. This supports the feasibility of correlating EV cargo composition with function in GBM treatment.

Abstract Intravital microscopy enables dynamic and real‐time visualisation of microscopic structures in living tissues without the need for fixation, with real‐life applicability being illustrated by several first‐in‐human studies in different cancers. Its use in preclinical models has yielded important observations of the microvasculature of both healthy and diseased tissues. It has further enabled the observation of the interactions between important components of the tissue microenvironment such as immune cells and neighbouring microvessels. Important recent technological advances, however, have enabled the translation of this technology to human use. Here, we review the main advances in intravital microscopy and some of the most recent uses in different human disease settings.

Background Spinal subdural empyema rarely involves the spinal cord and may result in devastating neurological deficits. These lesions typically require prompt diagnosis, surgical evacuation, and antibiotic therapy. Here, we present the clinical course, imaging, and narrated operative video of a thoracic spinal subdural empyema initially diagnosed as an intramedullary neoplasm. Case Description A 73-year-old female presented with a 6-month history of worsening thoracic myelopathy; over the last few weeks, she rapidly developed paraplegia. She was initially diagnosed with an enlarging thoracic intramedullary mass. A spinal biopsy was performed for the presumptive diagnosis of primary intramedullary central nervous system lymphoma. However, at surgery, the thoracic lesion proved to be a chronic subdural empyema (i.e., surrounded by arachnoid granulations and soft-purulent tissue). Interestingly, the operative specimen failed to grow any specific organism. Conclusion Spinal subdural empyema should be one of the differential diagnoses considered for patients presenting with intradural spinal cord lesions.