Brain Tumor Model Research Articles

TMIC-44. ANDROGEN LOSS WEAKENS ANTI-TUMOR IMMUNITY AND ACCELERATES BRAIN TUMOR GROWTH

Abstract Many cancers, including glioblastoma (GBM), exhibit a male-biased incidence and outcome disparity. The underlying reasons for this sex bias are unclear but likely involve differences in tumor cell state and immune response. This effect is further influenced by sex hormones, including androgens, which have been shown to inhibit anti-tumor T cell immunity in other solid tumors. Using a series of pre-clinical models, we observed that androgens drive anti-tumor immunity in brain tumors, contrasting with their effect in other tumor types. Upon castration, tumor growth was accelerated in GBM and brain tumor models, while the opposite effect was observed when tumors were located outside the brain. This castration effect could be reversed by testosterone administration. Flow cytometry revealed decreased T cell function, indicated by reduced anti-tumor cytokines (IFNγ and TNFα), and increased T cell exhaustion in both tumors and peripheral tissues in castrated mice, suggesting systemic immunosuppression. Indeed, the survival difference was completely abrogated in T cell deficient mice (RAG1 knockout). Mechanistically, increased hypothalamus-pituitary-adrenal (HPA) axis activity in castrated mice was responsible for the observed systemic immunosuppression, particularly in those with brain tumors. Blocking glucocorticoid receptors reversed the accelerated tumor growth in castrated mice, indicating that elevated glucocorticoid signaling mediated the castration effect. This mechanism was brain-specific rather than GBM-specific, as hyperactivation of the HPA axis was also observed with intracranial implantation of non-GBM tumors. Neuroinflammation caused by brain tumors was stronger in castrated mice, and proinflammatory cytokines like IL-1 and TNF induced HPA axis hyperactivation. Together, these findings highlight that brain tumors drive distinct endocrine-mediated mechanisms in the androgen-deprived setting and highlight the importance of organ-specific effects on anti-tumor immunity.

CNSC-30. DETERMINING THE REGULATION AND FUNCTION OF ANGPT1 HIGH-GRADE GLIOMAS

Abstract Angiopoietin-1 (Angpt1) is a secreted protein that promotes angiogenesis and vascular stability in development and certain disease states through activation of the Tie2 receptor. However, little is known about its regulation and function in brain tumors. Angpt1 is upregulated in glial brain tumors, including high-grade gliomas and ependymomas. We find Angpt1 is expressed by specific cell populations within gliomas, along with non-tumor reactive astrocytes and perivascular mural cells. Leveraging an in vivo brain tumor modeling system we have generated glioma models to investigate how tumor cell state impacts Angpt1 expression, along with creating Angpt1 knock-out models. We find that Angpt1 expression is increased when glioma models are biased towards a more astrocytic and/or mesenchymal state, mirroring developmental expression patterns. Ongoing studies utilizing these models are being used to determine the mechanisms that regulate the dynamic expression of Angpt1 and its function in glioma pathogenesis, including tumor angiogenesis and blood-brain barrier function.

DDDR-03. DEVELOPMENT OF ANTI-TUMOR AROMA THERAPY FOR GLIOBLASTOMA WITH LEMONGRASS ESSENTIAL OIL

Abstract INTRODUCTION Aroma essential oils apply to cancer therapy because of their immune-enhancing and sedative effects, and their ability to reduce the side effects of chemotherapy. Recently, aroma essential oils have also been reported to have anti-tumor effects. We investigate the anti-tumor effects of aromatic compounds contained in essential oils as a novel treatment for glioblastoma. In this study, we analyzed the antitumor effect of lemongrass essential oil and investigated its antitumor aroma therapy for glioblastoma. methods and RESULTS Human glioblastoma cells (U87, T98G) and mouse brain tumor cells (RSV-M) were used in the study. Tumor cells were cultured in the presence of lemongrass essential oil for 72 hours, and the growth inhibitory effect was observed, suggesting that the evaporated lemongrass essential oil components acted on tumor cells in the vicinity. In addition, a similar effect was observed with citral alone, which is the main component of lemongrass. Analysis of the effects of citral revealed that citral strongly binds to MARK4 and inhibits its enzyme activity, and that citral decreases the phosphorylation of tau protein. Next, a mouse brain tumor model with RSV-M was established, and the anti-tumor effect of lemongrass essential oil was studied. The results showed that the mice that inhaled lemongrass essential oil for 12 h/day had a significantly prolonged survival period compared to the control group. DISCUSSION Citral is the main component of lemongrass essential oil, which contains 70-80% of lemongrass essential oil. This study suggests a mechanism of inhibition of tumor cell proliferation by citral in malignant gliomas. Citral is a volatile monoterpene, and its anti-tumor effect was demonstrated by diffusion through evaporation. CONCLUSION Citral in lemongrass essential oil shows anti-tumor effects and is expected to be applied to a new glioblastoma therapy using “aroma”

TMIC-09. DENDRITIC CELL DYSFUNCTION RESTRICTS TUMOR ANTIGEN SPREADING IN ADOPTIVE CELLULAR TRANSFER THERAPY-ESCAPED GLIOMAS: IMPLICATIONS FOR TUMOR IMMUNE EVASION

Abstract Dendritic cells (DCs) play a pivotal role in initiating anti-tumor immune responses. Our group has developed an adoptive cellular transfer therapy (ACT) that significantly increases the infiltration of DCs and T cells into tumors, markedly enhancing survival in murine brain tumor models. However, tumors develop mechanisms to restrict the immune surveillance and the efficacy of immunotherapy, leading to tumor escape. In this study, we identified a mechanism involving DC dysfunction in ACT-escaped brain tumors. The finding that DCs are enriched after ACT treatment prompts an investigation into whether DC function is impaired in ACT-escaped tumors. Our results showed that DCs from both primary and ACT-escaped tumors were dysfunctional in their ability to activate T cells when co-cultured with tumor-reactive T cells or OT1 T cells. RNA-seq data revealed that, compared to primary tumor DCs, ACT-escaped tumor DCs exhibited a more pronounced reduction in conventional DC markers and antigen-presenting genes, alongside increased tolerance markers. Gene set enrichment analysis indicated that epithelial-mesenchymal transition (EMT) and hypoxia pathways were significantly enriched in ACT-escaped tumor DCs, suggesting divergent DC dysfunction mechanisms in primary versus escaped tumors. The anti-tumor role of DCs is primarily exerted through the activation of tumor-reactive T cells. Therefore, we assessed the cytotoxicity and exhaustion status of T cells in tumors. Surprisingly, we found that T cells from ACT-escaped tumors exhibited significantly higher levels of cytotoxicity and lower levels of T cell exhaustion compared to primary tumors. This suggests a T cell exhaustion-independent mechanism in ACT-escaped tumors. We further demonstrated that T cells in ACT-escaped tumor are mainly sourced from the adoptive transferred T cells, which recognize primary tumor antigens but not escaped tumor antigens. These results suggest that a combined mechanism of tumor antigen shifting and impaired DC function leads to a failure of antigen spreading and tumor eradication.

EXTH-09. GENE MODIFICATION OF HEMATOPOIETIC STEM AND PROGENITOR CELLS FOR IMPROVEMENT OF IMMUNOTHERAPIES FOR MALIGNANT GLIOMAS

Abstract Patients living with high-grade gliomas have a poor survival prognosis. Furthermore, standard of care treatment for these malignant gliomas has not significantly improved in the past decades. Our laboratory previously demonstrated that the combination of two different immunotherapies with HSPCs provided a significant survival benefit in preclinical brain tumor models, however, this therapeutic combination is still not 100% curative. We hypothesized that gene modification of HSPCs could add additional therapeutic benefit to immunotherapies for the treatment of resistant gliomas. Hematopoietic stem and progenitor cells (HSPCs) have been widely used in different clinical settings due to their ability to self-renew and differentiate into all immune cell lineages. In recent years, HSPCs have been the target of a variety of gene editing research efforts to decipher the most effective method for gene modification to use for therapeutic purposes. After comparison with previously established methods, we optimized a protocol for the successful editing of murine HSPCs and human CD34+ cells. Using Cas9 mRNA and sgRNAs in HSPCs, we achieved up to 80% reduction in gene expression. This method is superior to others due to its efficient, quick, inexpensive, and reliable nature. We also showed that, by knocking-down IL-6R in HSPCs, we can drive their differentiation into dendritic cells, while decreasing MDSCs and macrophages. Furthermore, gene-modified HSPCs are also capable of bone marrow reconstitution of lethally irradiated mice. Currently, we are testing whether the combination of gene-modified HSPCs with immunotherapy provides additional survival benefit to unmodified HSPCs with immunotherapy in a resistant murine glioma model.

Development of a murine laser interstitial thermotherapy system.

The objective of this study was to develop a murine system for the delivery of laser interstitial thermotherapy (LITT) with probe-based thermometry as a model for human glioblastoma treatment to investigate thermal diffusion in heterogeneous brain tissue. First, the tissue heating properties were characterized using a diode-pumped solid-state near-infrared laser in a homogeneous tissue model. The laser was adapted for use with a repurposed stereotactic surgery frame utilizing a micro laser probe and Hamilton syringe. The authors designed and manufactured a stereotactic frame attachment to work as a temperature probe stabilizer. Application of this novel design was used as a precise method for real-time thermometry at known distances from the thermal ablative center mass during murine LITT studies. Temperature measurements were achieved during LITT that verified the direct thermometry capability of the system without the need for MR-based thermal monitoring. Application of multiple stereotactic design iterations led to an accurately reproducible surgical laser ablation procedure. Histological staining confirmed precise thermal ablation and controllable lesion size based on time and temperature control. Treatment of a syngeneic intracranial glioma model highly resistant to conventional therapy resulted in a modest survival benefit. The authors have successfully developed a murine model system of LITT with direct in situ thermometry for investigation into the effects of thermal ablation and combinatorial treatments in murine brain tumor models.

A Mathematical Model of Brain Tumor with Glia-Neurons Interaction and Chemo-Virotherapy Treatment

A Mathematical Model of Brain Tumor with Glia-Neurons Interaction and Chemo-Virotherapy Treatment

Polymer-locking fusogenic liposomes for glioblastoma-targeted siRNA delivery and CRISPR-Cas gene editing.

In patients with glioblastoma (GBM), upregulated midkine (MDK) limits the survival benefits conferred by temozolomide (TMZ). RNA interference (RNAi) and CRISPR-Cas9 gene editing technology are attractive approaches for regulating MDK expression. However, delivering these biologics to GBM tissue is challenging. Here we demonstrate a polymer-locking fusogenic liposome (Plofsome) that can be transported across the blood-brain barrier (BBB) and deliver short interfering RNA or CRISPR-Cas9 ribonucleoprotein complexes into the cytoplasm of GBM cells. Plofsome is designed by integrating a 'lock' into the fusogenic liposome using a traceless reactive oxygen species (ROS)-cleavable linker so that fusion occurs only after crossing the BBB and entering the GBM tissue with high ROS levels. Our results showed that MDK suppression by Plofsomes significantly reduced TMZ resistance and inhibited GBM growth in orthotopic brain tumour models. Importantly, Plofsomes are effective only at tumour sites and not in normal tissues, which improves the safety of combined RNAi and CRISPR-Cas9 therapeutics.

Galectin-9 Mediates the Functions of Microglia in the Hypoxic Brain Tumor Microenvironment.

Galectin-9 is a multifaceted regulator of various pathophysiological processes that exerts positive or negative effects in a context-dependent manner. Here, we elucidated the distinctive functional properties of galectin-9 on myeloid cells within the brain tumor microenvironment. Galectin-9-expressing cells were abundant at the hypoxic tumor edge in the tumor-bearing ipsilateral hemisphere compared to the contralateral hemisphere in an intracranial mouse brain tumor model. Galectin-9 was highly expressed in microglia and macrophages in tumor-infiltrating cells. In primary glia, both the expression and secretion of galectin-9 were influenced by tumors. Analysis of a human glioblastoma bulk RNA-sequencing dataset and a single-cell RNA-sequencing dataset from a murine glioma model revealed a correlation between galectin-9 expression and glial cell activation. Notably, the galectin-9high microglial subset was functionally distinct from the galectin-9neg/low subset in the brain tumor microenvironment. Galectin-9high microglia exhibited properties of inflammatory activation and higher rates of cell death, whereas galectin-9neg/low microglia displayed a superior phagocytic ability against brain tumor cells. Blockade of galectin-9 suppressed tumor growth and altered the activity of glial and T cells in a mouse glioma model. Additionally, glial galectin-9 expression was regulated by Hif-2α in the hypoxic brain tumor microenvironment. Myeloid-specific Hif-2α deficiency led to attenuated tumor progression. Together, these findings reveal that galectin-9 on myeloid cells is an immunoregulator and putative therapeutic target in brain tumors.

Comprehensive insight into 3D bioprinting technology for brain tumor modeling

Glioblastoma is one of the most common primary malignant brain tumors with a poor prognosis and high mortality rate. Because only small lipophilic molecules can penetrate the blood-brain barrier, chemotherapy and immunotherapy are limited in their ability to effectively treat brain tumor. Three-dimensional (3D) bioprinting has the potential to model the 3D environment of human pathology and diseases directly. In many cancers, 3D bioprinting technology closely mimics the tumor microenvironment, making it a promising tool for drug screening and uncovering the mechanisms of cancer initiation and progression. Recent 3D bioprinting technologies have been developed to recreate the dynamic interactions between the tumor and endothelial cells. Brain tumor models using 3D bioprinting technology can reconstruct the biophysical heterogeneity and immune interactions in the brain. These advanced models regulate the organization of tumor structures for preclinical drug testing and reveal the immunological pathways involved in brain tumor. Here, we highlight 3D bioprinting technologies that can replace conventional in vitro models for brain tumor treatment.

The emerging field of viroimmunotherapy for pediatric brain tumors.

Pediatric brain tumors are the most common solid tumors in children. Even to date, with the advances in multimodality therapeutic management, survival outcomes remain dismal in some types of tumors, such as pediatric-type diffuse high-grade gliomas or central nervous system embryonal tumors. Failure to understand the complex molecular heterogeneity and the elusive tumor and microenvironment interplay continues to undermine therapeutic efficacy. Developing a strategy that would improve survival for these fatal tumors remains unmet in pediatric neuro-oncology. Oncolytic viruses (OVs) are emerging as a feasible, safe, and promising therapy for brain tumors. The new paradigm in virotherapy implies that the direct cytopathic effect is followed, under certain circumstances, by an antitumor immune response responsible for the partial or complete debulking of the tumor mass. OVs alone or combined with other therapeutic modalities have been primarily used in adult neuro-oncology. A surge in encouraging preclinical studies in pediatric brain tumor models recently led to the clinical translation of OVs with encouraging results in these tumors. In this review, we summarize the different virotherapy tested in preclinical and clinical studies in pediatric brain tumors, and we discuss the limitations and future avenues necessary to improve the response of these tumors to this type of therapy.

Potential for boron neutron capture therapy (BNCT) with ASCT2-targeted boron agents.

233 Background: Boron Neutron Capture Therapy (BNCT) is a cutting-edge particle irradiation technique that utilizes the nuclear reaction triggered by the irradiation of non-radioactive boron-10 with thermal neutrons, selectively annihilating tumor cells that have incorporated boron. In the clinical arena, Boronophenylalanine (BPA), a phenylalanine compound targeting amino acid receptors, has been the cornerstone of BNCT. While BNCT has been effective against malignant gliomas, its dependency on BPA uptake has illuminated the existence of inherent resistance within specific cells, tissues, and cancer types. This study pivots towards the Alanine-serine-cysteine transporter 2 (ASCT2)—a transporter distinct from LAT1—investigating its potential as a gateway for the development of innovative boron carriers, with the aim of expanding the clinical applicability and effectiveness of BNCT. Methods: This research embarked on in vitro investigations to evaluate boron accumulation in F98 and C6 rat glioma cells, and 9L rat gliosarcoma, following 24 hours of exposure to BPA and GluB-2 (10 μg B/ml each). Complementary in vivo studies involved the intravenous administration of these compounds to an F98 rat brain tumor model, with the subsequent measurement of boron distribution at 2.5, 6, and 24 hours post-administration. The efficacy of these treatments was then ascertained through neutron irradiation experiments, gauging therapeutic outcomes via the survival periods of the subjects. Results: In vitro findings highlighted that GluB-2 facilitated a significantly higher intracellular boron concentration compared to BPA in F98 cells (p=0.02, Student's t-test). In vivo results indicated that the apex of boron biodistribution in tumors was achieved at 2.5 hours post-BPA treatment and at 6 hours post-GluB-2 treatment, with GluB-2 securing a superior maximum intratumor boron concentration. Survival analysis revealed a mean survival of 28.0±2.5 days for the neutron alone group, 37.7±5.0 days for the group receiving BPA IV + BNCT at 2.5 hours, 55.1±19.9 days for the group treated with GluB-2 IV + BNCT at 6 hours, and 25.3±1.4 days for the untreated group. Remarkably, the group treated with GluB-2 demonstrated significantly prolonged survival compared to the BPA-treated group (p<0.001, log-rank test). Conclusions: Combining BNCT with GluB-2 showed superior efficacy over BPA. Further research is needed to optimize boron concentration timing and ASCT2 expression levels, yet GluB-2 presents a promising advancement in BNCT, potentially transforming malignant brain tumor treatment.

AB020. Flagellin synergistically enhances anti-tumor effect of EGFRvIII peptide in a glioblastoma-bearing mouse brain tumor model.

Glioblastoma (GBM) is the most aggressive type of brain tumor with heterogeneity and strong invasive ability. Treatment of GBM has not improved significantly despite the progress of immunotherapy and classical therapy. Epidermal growth factor receptor variant III (EGFRvIII), one of GBM-associated mutants, is regarded as an ideal therapeutic target in EGFRvIII-expressed GBM patients because it is a tumor-specific receptor expressed only in tumors. Flagellin B (FlaB) originated from Vibrio vulnificus, is known as a strong adjuvant that enhances innate and adaptive immunity in various vaccine models. This study investigated whether FlaB synergistically could enhance the anti-tumor effect of EGFRvIII peptide (PEGFRvIII). EGFRvIII-GL261/Fluc cells were used for GBM-bearing mouse brain model. Cell-bearing mice were inoculated with phosphate-buffered saline (PBS), FlaB alone, PEGFRvIII alone, and PEGFRvIII plus FlaB. Tumor growth based on magnetic resonance imaging (MRI) and the survival rate was investigated. T cell population was examined by flow cytometry analysis. Both cleaved caspase-3 and CD8+ lymphocytes were shown by immunohistochemistry (IHC) staining. The PEGFRvIII plus FlaB group showed delayed tumor growth and increased survival rate when compared to other treatment groups. As evidence of apoptosis, cleaved caspase-3 expression and DNA disruption were more increased in the PEGFRvIII plus FlaB group than in other groups. In addition, the PEGFRvIII plus FlaB group showed more increased CD8+ T cells and decreased Treg cells than other treatment groups in the brain. FlaB can enhance the anti-tumor effect of PEGFRvIII by increasing CD8+ T cell response in a mouse brain GBM model.

In vivo mouse models for adult brain tumors: Exploring tumorigenesis and advancing immunotherapy development.

Brain tumors, particularly glioblastoma (GBM), are devastating and challenging to treat, with a low 5-year survival rate of only 6.6%. Mouse models are established to understand tumorigenesis and develop new therapeutic strategies. Large-scale genomic studies have facilitated the identification of genetic alterations driving human brain tumor development and progression. Genetically engineered mouse models (GEMMs) with clinically relevant genetic alterations are widely used to investigate tumor origin. Additionally, syngeneic implantation models, utilizing cell lines derived from GEMMs or other sources, are popular for their consistent and relatively short latency period, addressing various brain cancer research questions. In recent years, the success of immunotherapy in specific cancer types has led to a surge in cancer immunology-related research which specifically necessitates the utilization of immunocompetent mouse models. In this review, we provide a comprehensive summary of GEMMs and syngeneic mouse models for adult brain tumors, emphasizing key features such as model origin, genetic alteration background, oncogenic mechanisms, and immune-related characteristics. Our review serves as a valuable resource for the brain tumor research community, aiding in the selection of appropriate models to study cancer immunology.

STEM-05. CREATING PATIENT-DERIVED TUMOROIDS TO INVESTIGATE RADIORESISTANCE IN PEDIATRIC BRAIN TUMORS

Abstract BACKGROUND Brain cancers are the most frequently diagnosed tumor types in pediatric and young adult populations. Unfortunately, they often carry a poor prognosis and face common challenges such as treatment resistances due to intra- and intertumoral heterogeneity. To fully understand the intrinsic and extrinsic mechanisms which might hinder proper care, there is an emerging need to develop precise models of brain tumors to understand resistances and to predict therapeutic responses. While tumor-derived primary cell lines are relatively easy to produce, fully replicate the complexity of tumors as they grow without interactions with and from the microenvironment. Therefore, the advent of organoid cultures represents a significant advancement in modelling development. Derived from this technology, tumoroids offer a promising solution for modeling 3D tumors and their complex microenvironment. METHODS We develop tumoroids from fresh biopsies and patient-derived tumor xenografts. These models were rigorously validated against to initial tumor using confocal microscopy, methylome analyses, metabolomics and single-cell RNAseq. To assess the intrinsic hypoxic environment and its spatial heterogeneity, characteristic of aggressive cancers, we employed fluorescent oxygen-sensitive dye loaded polymeric nanorods. RESULTS We successfully generated tumoroids using PDX of ependymomas (BT39) and it paired relapse (BT42), two H3.3 mutated high-grade gliomas (BT35 and BT69), one ganglioglioma (BT63) and directly from fresh biopsies of DIPG sample (BT140). Several passages were obtained after primary derivation, and cryopreservation demonstrating the stability of the models over time. Tumoroids displayed similar protein and omics markers as their parental tumors and harbored specific stem cell and neural progenitor markers. The methylation patterns were entirely preserved comparing 3D models and their parental tumors, and other multiomics and metabolic approaches confirmed the accurate reconstitution of tumor complexity. The study of oxygen-sensitive nanorods highlighted the heterogeneous oxygen gradient within tumoroids. CONCLUSIONS All these initial characterized tumoroids helped us to develop radioresistant paired models.

MDB-52. MYC-DRIVEN PEDIATRIC BRAIN TUMORS SHARE A COMMON PHOTORECEPTOR IDENTITY

Abstract Mouse models serve as invaluable tools for improving the understanding and treatment of pediatric brain tumors. We recently published a highly aggressive MYC-driven brain tumor model (GMYC), which exhibits approximately 70% penetrance. Our transcription profiling indicates that GMYC tumors accurately resemble human Group 3 medulloblastoma (MB-G3). Interestingly, a strong photoreceptor program was activated in the tumor model. This is commonly upregulated in MB-G3 but also in pineoblastoma (PB), another malignant pediatric brain tumor. CRX, a transcription factor critical for pineal cell development is also a master regulator for MB-G3 maintenance. By studying early tumor initiation using Crx-lineage tracing and scRNA-seq, we confirmed that GMYC tumors originate from early pinealocytes. Exome sequencing of GMYC tumors further confirmed mutations of epigenetic regulators commonly reported in either PB or MB. To investigate tumor development from photoreceptor-positive progenitors in the developing brain, we performed Crx-lineage tracing with tamoxifen injections, confirming that Crx-positive cells exist in pineal gland progenitors. However, Crx-traced cells also marked granule neurons in the flocculonodular lobe of the cerebellum, which is the suggested site of MB-G3 origin arising from the developing rhombic lip. To investigate if the Myc oncogene can generate different types of pediatric brain tumors in Crx-positive cells, an XMYCT58A-Tomato mouse model was established by crossing Crx-CreERT2; LSL-MycT58A and Rosa26LSL-tdTomato strains. Here, MycT58A was turned on with tamoxifen injection after birth and tumor development followed using the tdTomato reporter. XMYCT58A-Tomato mice developed brain tumors from both the pineal gland and cerebellum after 2-6 months. Histologically, tumors were non-glial (GFAP-, Olig2-), showed neuronal activity (Neurod1+), and stained positive for photoreceptor identity markers (CRX+, OTX2+) similar to both MB-G3 and PB-MYC. Collectively, our data suggest that both MYC-driven MB-G3 and PB-MYC originate from photoreceptor-positive cells, which has implications for developing novel treatments targeting these devastating childhood malignancies.

A viral attack on brain tumors: the potential of oncolytic virus therapy.

Managing malignant brain tumors remains a significant therapeutic hurdle that necessitates further research to comprehend their treatment potential fully. Oncolytic viruses (OVs) offer many opportunities for predicting and combating tumors through several mechanisms, with both preclinical and clinical studies demonstrating potential. OV therapy has emerged as a potent and effective method with a dual mechanism. Developing innovative and effective strategies for virus transduction, coupled with immune checkpoint inhibitors or chemotherapy drugs, strengthens this new technique. Furthermore, the discovery and creation of new OVs that can seamlessly integrate gene therapy strategies, such as cytotoxic, anti-angiogenic, and immunostimulatory, are promising advancements.This review presents an overview of the latest advancements in OVs transduction for brain cancer, focusing on the safety and effectiveness of G207, G47Δ, M032, rQNestin34.5v.2, C134, DNX-2401, Ad-TD-nsIL12, NSC-CRAd-S-p7, TG6002, and PVSRIPO. These are evaluated in both preclinical and clinical models of various brain tumors.

Optimization, Characterization, and Comparison of Two Luciferase-Expressing Mouse Glioblastoma Models.

Glioblastoma (GBM) is the most aggressive brain cancer. To model GBM in research, orthotopic brain tumor models, including syngeneic models like GL261 and genetically engineered mouse models like TRP, are used. In longitudinal studies, tumor growth and the treatment response are typically tracked with in vivo imaging, including bioluminescence imaging (BLI), which is quick, cost-effective, and easily quantifiable. However, BLI requires luciferase-tagged cells, and recent studies indicate that the luciferase gene can elicit an immune response, leading to tumor rejection and experimental variation. We sought to optimize the engraftment of two luciferase-expressing GBM models, GL261 Red-FLuc and TRP-mCherry-FLuc, showing differences in tumor take, with GL261 Red-FLuc cells requiring immunocompromised mice for 100% engraftment. Immunohistochemistry and MRI revealed distinct tumor characteristics: GL261 Red-FLuc tumors were well-demarcated with densely packed cells, high mitotic activity, and vascularization. In contrast, TRP-mCherry-FLuc tumors were large, invasive, and necrotic, with perivascular invasion. Quantifying the tumor volume using the HALO® AI analysis platform yielded results comparable to manual measurements, providing a standardized and efficient approach for the reliable, high-throughput analysis of luciferase-expressing tumors. Our study highlights the importance of considering tumor engraftment when using luciferase-expressing GBM models, providing insights for preclinical research design.

A Scoping Review of Focused Ultrasound Enhanced Drug Delivery for Across the Blood-Brain Barrier for Brain Tumors.

Previous mechanisms of opening the blood-brain barrier (BBB) created a hypertonic environment. Focused ultrasound (FUS) has recently been introduced as a means of controlled BBB opening. Here, we performed a scoping review to assess the advances in drug delivery across the BBB for treatment of brain tumors to identify advances and literature gaps. A review of current literature was conducted through a MEDLINE search inclusive of articles on FUS, BBB, and brain tumor barrier, including human, modeling, and animal studies written in English. Using the Rayyan platform, 2 reviewers (J.P and C.Y) identified 967 publications. 224 were chosen to review after a title screen. Ultimately 98 were reviewed. The scoping review was designed to address the following questions: (1) What FUS technology improvements have been made to augment drug delivery for brain tumors? (2) What drug delivery improvements have occurred to ensure better uptake in the target tissue for brain tumors? Microbubbles (MB) with FUS are used for BBB opening (BBBO) through cavitation to increase its permeability. Drug delivery into the central nervous system can be combined with MB to enhance transport of therapeutic agents to target brain tissue resulting in suppression of tumor growth and prolonging survival rate, as well as reducing systemic toxicity and degradation rate. There is accumulating evidence demonstrating that drug delivery through BBBO with FUS-MB improves drug concentrations and provides a better impact on tumor growth and survival rates, compared with drug-only treatments. Here, we review the role of FUS in BBBO. Identified gaps in the literature include impact of tumor microenvironment and extracellular space, improved understanding and control of MB and drug delivery, further work on ideal pharmacologics for delivery, and clinical use.

Receptor Ligand-Free Mesoporous Silica Nanoparticles: A Streamlined Strategy for Targeted Drug Delivery across the Blood-Brain Barrier.

Mesoporous silica nanoparticles (MSNs) represent a promising avenue for targeted brain tumor therapy. However, the blood-brain barrier (BBB) often presents a formidable obstacle to efficient drug delivery. This study introduces a ligand-free PEGylated MSN variant (RMSN25-PEG-TA) with a 25 nm size and a slight positive charge, which exhibits superior BBB penetration. Utilizing two-photon imaging, RMSN25-PEG-TA particles remained in circulation for over 24 h, indicating significant traversal beyond the cerebrovascular realm. Importantly, DOX@RMSN25-PEG-TA, our MSN loaded with doxorubicin (DOX), harnessed the enhanced permeability and retention (EPR) effect to achieve a 6-fold increase in brain accumulation compared to free DOX. In vivo evaluations confirmed the potent inhibition of orthotopic glioma growth by DOX@RMSN25-PEG-TA, extending survival rates in spontaneous brain tumor models by over 28% and offering an improved biosafety profile. Advanced LC-MS/MS investigations unveiled a distinctive protein corona surrounding RMSN25-PEG-TA, suggesting proteins such as apolipoprotein E and albumin could play pivotal roles in enabling its BBB penetration. Our results underscore the potential of ligand-free MSNs in treating brain tumors, which supports the development of future drug-nanoparticle design paradigms.