Brain Tumor Model Research Articles

Exact solutions through symmetry reductions for a high-grade brain tumor model with response to hypoxia

Mathematical biology models can simulate cell behavior scenarios, specifically for tumor proliferation. In this paper, we study a continuous model describing the evolution of high-grade gliomas from the point of view of the theory of symmetry reductions in partial differential equations (PDEs). Malignant gliomas are the most frequent and deadly type of brain tumor. Over the last few years, complex mathematical models of cancerous growths have been developed increasingly, especially on solid tumors, in which growth primarily comes from abnormal cellular proliferation. The presented PDE system includes two different cellular phenotypes, depending on their oxygenation level. Furthermore, this mathematical model assumes that both phenotypes differ in migration and proliferation rates. Specifically, it includes the possibility of hypoxic cells diffusing into well-oxygenated areas of a tumor. Our main findings are obtained through the classical symmetries admitted by the proposed system, and transformation groups are used to reduce the PDE system to ordinary differential equations. By these means, we provide not only exact solutions but also capture a 3-dimensional representation of the biological phenomenon. The simulations provided show the relationship between normoxic and hypoxic phenotypes in high-grade gliomas.

Abstract LB344: Complement-mediated signaling during cross-presentation of tumor antigen augments T cell responses

Abstract Production of complement C3a and C5a locally at the immune synapse by activated dendritic cells (DCs) enhances T cell responses in multiple experimental models. Complement signaling through cognate C3a receptor (C3aR) and C5a receptor (C5aR) modulate effector T cell stability, proliferation and differentiation. We have previously shown that complement C3 plays a mechanistic role in driving synergistic anti-tumor effects of blocking indoleamine 2,3-dioxygenase (IDO) during radiation and chemotherapy in a murine brain tumor model that expresses the gp10025-33 peptide antigen. We hypothesize that, when anti-tumor responses are allowed to happen, complement C3 production by local DCs acts as a costimulation factor, operating through C3aR and C5aR on the T cell surface to allow optimal T cell activation and proliferation. To study the role of complement C3 as a costimulation factor during T cell responses against a nominal tumor antigen (gp10025-33 peptide, expressed by B16F10 melanoma), we used T cells from syngeneic pmel-1 mice (TCR transgenic with CD8 T cells that recognize the cross-presented gp10025-33 peptide) co-cultured with gp10025-33 peptide and dendritic cells from either wild-type (WT) or C3-defiecient (C3-KO) mice. In addition, we used in vitro culture conditions where gp10025-33 tumor peptide was in stringent limited supply to model homeostatic conditions of the tumor microenvironment. We found that, when stimulated by DCs from C3-KO mice, pmel-1 CD8 T cells had decreased activation marker expression, proliferation, and cytokine effector function relative to stimulation by DCs from WT mice. Next, we bred pmel-1 mice onto a syngeneic background deficient in receptors for both C3a and C5a complement factors (C3aR-KO/C5aR-KO double knock-out mice). We used CD8 T cells from the resulting mouse strain (pmel-1/C3aR-KO/C5aR-KO) co-cultured with WT DCs to study the role of complement signaling in T cells during responses to tumor antigen. Using the same stringent antigen conditions, CD8 T cells from the pmel-1/C3aR-KO/C5aR-KO mice had decreased activation marker expression and proliferation, and differences in cytokine function compared to CD8 T cells from the pmel-1 mice. These findings suggest that lack of local complement production by the DCs in the tumor microenvironment may inhibit anti-tumor immune responses, and that complement signaling through C3aR and C5aR on T cells may play an important role during such anti-tumor responses. Citation Format: Caryn L. Bird, Gabriela A. Pacholczyk, Theodore S. Johnson. Complement-mediated signaling during cross-presentation of tumor antigen augments T cell responses [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr LB344.

A prediction model for magnetic particle imaging–based magnetic hyperthermia applied to a brain tumor model

Background and objectiveBrain tumor is a global health concern at the moment. Thus far, the only treatments available are radiotherapy and chemotherapy, which have several drawbacks such as low survival rates and low treatment efficacy due to obstruction of the blood-brain barrier. Magnetic hyperthermia (MH) using magnetic nanoparticles (MNPs) is a promising non-invasive approach that has the potential for tumor treatment in deep tissues. Due to the limitations of the current drug-targeting systems, only a small proportion of the injected MNPs can be delivered to the desired area and the rest are distributed throughout the body. Thus, the application of conventional MH can lead to damage to healthy tissues. MethodsMagnetic particle imaging (MPI)-guided treatment platform for MH is an emerging approach that can be used for spatial localization of MH to arbitrarily selected regions by using the MPI magnetic field gradient. Although the feasibility of this method has been demonstrated experimentally, a multidimensional prediction model, which is of crucial importance for treatment planning, has not yet been developed. Hence, in this study, the time dependent magnetization equation derived by Martsenyuk, Raikher, and Shliomis (which is a macroscopic equation of motion derived from the Fokker-Planck equation for particles with Brownian relaxation mechanism) and the bio-heat equations have been used to develop and investigate a three-dimensional model that predicts specific loss power (SLP), its spatio-thermal resolution (temperature distribution), and the fraction of damage in brain tumors. ResultsBased on the simulation results, the spatio-thermal resolution in focused heating depends, in a complex manner, on several parameters ranging from MNPs properties to magnetic fields characteristics, and coils configuration. However, to achieve a high performance in focused heating, the direction and the relative amplitude of the AC magnetic heating field with respect to the magnetic field gradient are among the most important parameters that need to be optimized. The temperature distribution and fraction of the damage in a simple brain model bearing a tumor were also obtained. ConclusionsThe complexity in the relationship between the MNPs properties and fields parameter imposes a trade-off between the heating efficiency of MNPs and the accuracy (resolution) of the focused heating. Therefore, the system configuration and field parameters should be chosen carefully for each specific treatment scenario. In future, the results of the model are expected to lead to the development of an MPI-guided MH treatment platform for brain tumor therapy. However, for more accurate quantitative results in such a platform, a magnetization dynamics model that takes into account coupled Néel-Brownian relaxation mechanism in the MNPs should be developed.

Abstract 2882: Characteristic immunomodulatory role of myeloid galectin-9 in the brain tumor microenvironment

Abstract Galectin-9 is a member of galectin family with carbohydrate-recognition domains that specifically bind to β-galactoside. Increasing reports have suggested that galectin-9 can bind and interact with immune-modulatory molecules including TIM-3 in several pathophysiological conditions, especially in T cells. However, to date, little is known about the galectin-9 in myeloid cells under tumor microenvironment. In this study, we explored the expressional characteristics and roles of galectin-9 in the brain tumor microenvironment using an intracranial mouse brain tumor model and in vitro system. We found that expression level of galectin-9 was markedly elevated in ipsilateral hemisphere compared to contralateral hemisphere of intracranial brain tumor model. FACS analyses showed that galectin-9 expression was higher in CD45highCD11bhigh macrophages and CD45midCD11bhigh microglia as well as lymphocytes from ipsilateral region than those from contralateral region. In addition, galectin-9 levels were increased after exposure to GL26 brain tumor cells in in vitro co-culture system using primary microglia. Interestingly, phagocytic activity, a key function of myeloid cells, was significantly reduced in galecin-9+ microglia compared to galecin-9- microglia when co-cultured with GL26-GFP cells. Furthermore, SIRPα levels were higher in galectin-9+ microglia than galecin-9- microglia. Similar results were observed in macrophages. Collectively, these findings suggest that galectin-9 may be an important modulatory molecule in myeloid cells under brain tumor microenvironment. Citation Format: Chanju Lee, Dahee Yu, Eun Jung Park. Characteristic immunomodulatory role of myeloid galectin-9 in the brain tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2882.

Abstract 5498: SHP2 inhibition enhances antitumor effect of mirdametinib in a pediatric brain tumor model bearing CDC42SE2BRAF fusion by rewiring the proteome and phosphoproteome landscape

Abstract Pediatric gliomas are the most common type of pediatric brain tumors representing wide range of molecularly and clinically heterogenous subtypes. The hyperactivity of mitogen-activated protein kinases (MAPK) pathway has been identified in the majority of pediatric glioma suggesting its therapeutic potential. However, pharmacologic targeting single MAPK pathway’s component is limited due to the development of drug resistance and differential response associated with tumor molecular landscape. Therefore, effective combination strategy in the framework of precision medicine is needed. Here we report combination benefit and molecular underpinning therapeutic response of brain penetrant MEK inhibitor (mirdametinib) and SHP2 inhibitor (SHP099) in a pediatric patient derived xenograft (PDX) and xenoline developed at our institution. Our model was derived from a pediatric patient who was diagnosed with rare high-grade subtype of glioma, anaplastic pleomorphic xanthoastrocytoma, and did not respond to MEK inhibitor, trametinib. Integrative multi-omics revealed molecular fidelity between our model and its patient tumor counterpart including the presence of 7q35 fusion, CDC52SE2-BRAF, CDKN2A/B loss, and MAPK pathway hyperactivation. In vitro studies using our xenoline IU-X128 demonstrated synergy between SHP099 and mirdametinib to curtail cell proliferation (p<0.05). Moreover, this combination was well tolerated in our PDX, IU-RHT128, and potentiated anti-tumor effect of the single agent within clinically achievable doses. Reverse Phase Proteome Array (RPPA) identified MAPK reactivation via Mushasi RNA binding protein-PI3K-AKT crosstalk as a potential innate resistance mechanism to single agent MEK inhibitor in the PDX tumor. Further, tandem mass tags (TMT)-LC-MS/MS profiling on tumor treated with single agent SHP099 or mirdametinib and their combination revealed that combination therapy does not only revert certain proteome and phosphoproteome reprogramming from single agent treatment but also created a novel landscape which can be associated with anti-tumor effect. In this case, kinase network reprograming leading to MAPK reactivation was identified in mirdametinib treated tumor which was attenuated in the combination treatment. In summary, our results demonstrated that combination SHP099 and mirdametinib is superior to single agent alone in the pediatric A-PXA brain tumor model with proteome and phosphoproteome reprogramming of multiple networks as potential molecular mechanisms underlying therapeutic benefit of combination therapy. Ultimately, clinical translation of this finding will potentially benefit patient of this malignant rare pediatric glioma subset which currently does not have standard therapy. Citation Format: Nur P. Damayanti, Anthony Alfonso, Josue D. Ordaz, Erika Dobrota, M. Reza Saadatzadeh, Pankita Pandya, Barbara J. Bailey, Khadijeh Bijangi-Vishehsaraei, Harlan E. Shannon, Kathy Coy, Melissa Trowbridge, Anthony L. Sinn, Rosa Gallager, Julia Wulfkuhle, Emanuel Petricoin, Amber Mosley, Mark S. Marshall, Alex Lion, Michael J. Fergusson, Karl Balsara, Karen E. Pollok. SHP2 inhibition enhances antitumor effect of mirdametinib in a pediatric brain tumor model bearing CDC42SE2BRAF fusion by rewiring the proteome and phosphoproteome landscape. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5498.

Abstract 2730: Antisense-oligonucleotide therapy targeting BRAF alleviates pediatric brain tumors with intractable epilepsy

Abstract Rationale: BRAF mutations leading to aberrant MAPK/ERK signaling are one of the major driver mutations in low-grade pediatric brain tumors (e.g., pilocytic astrocytoma, ganglioglioma, dysembryoplastic neuroepithelial tumor, and diffuse astrocytoma). These variants are highly associated with poor prognosis and intractable epilepsy. We previously identified that BRAF mutations originate from neural stem cells during embryonic brain development and lead to epilepsy-associated pediatric brain tumors (Koh et al, Nat Med 2018). Existing BRAF inhibitors such as Vemurafenib and Dabrafenib are specific to BRAF V600E protein and have limited penetrance into the blood-brain barrier (BBB). Antisense oligonucleotide (ASO) therapy via intrathecal injection bypasses BBB and degrades the transcript of the target gene in the brain. Thus, it is a promising and effective therapeutic tool in neurological disorders with genetically and molecularly identified targets. Methods: We developed the genetically engineered mouse model of Braf-derived pediatric brain tumors with intractable epilepsy by introducing Braf p.V600E mutation into neural stem cells during embryonic brain development. These mice show a gradual increase in tumor size and epileptic seizures and a decrease in survival rate over time, thereby recapitulating BRAF-derived pediatric brain tumors with intractable epilepsy. We administrated the most effective ASO inhibiting mouse Braf RNA selected by in silico and in vitro screening. ASO was delivered by single bolus intracerebroventricular (i.c.v.) injection at 10 weeks after pre-monitoring of behavior seizure and tumor size. Results: Oral administration of existing BRAF inhibitors could not significantly reduce seizures and tumor size in BRAF pediatric tumor models. Single ICV injection of Braf ASO successfully reduced the transcript and encoded protein in a dose-dependent manner and its knock-down effect lasted at least 3 months. Injected ASOs are well distributed to CD34-positive regions and tumor cells in Braf-derived neuro-glial tumors. The behavioral and electrographic seizure frequency is remarkably reduced after treatment of the ASO. The size of tumors and enlarged dysmorphic neurons are significantly reduced. The survival rate was significantly increased. Also, the bodyweight is rescued in Braf ASO treated group, compared to the vehicle-treated control group. No behavioral and molecular toxicity was found at two months after i.c.v. administration of ASO. Conclusions: In our study, ASO therapy targeting BRAF shows strong therapeutic effects on various aspects of BRAF-derived pediatric brain tumors, including the epileptic seizures, tumor size, survival rate as well as dysmorphic neurons. Therefore, ASO therapy targeting BRAF will be a promising and effect therapy in BRAF-derived pediatric brain tumors with intractable epilepsy. Citation Format: Jeong Ho Lee, Seyeon Kim. Antisense-oligonucleotide therapy targeting BRAF alleviates pediatric brain tumors with intractable epilepsy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2730.

Abstract 3582: Differentiation of niraparib and olaparib brain penetration in a mouse brain metastatic tumor model

Abstract Purpose: There remains an unmet need to provide effective treatment therapy for patients with primary and metastatic brain tumors; lack of drug penetration across the blood brain barrier (BBB) is a key factor. Synthetic lethality remains an attractive mechanism in treating brain tumors post radiotherapy. Here, we evaluated brain penetration and distribution of niraparib and olaparib in a mouse brain tumor model. Experimental: Female mice (CrTac:NCr-Foxn1nu; 6 w/o) received 2.5E5 luciferase transfected human breast cancer line (MDA 231-BRM2-831) via intracardiac injection. Mice were imaged twice/week using bioluminescence imaging (BLI) to monitor tumor growth. On day 35, mice with brain metastases (BM) were treated via oral gavage once daily for 5 days with either niraparib (35 mg/kg, n=4 BM, n=3 control), olaparib (50 mg/kg, n=3 BM, n=3 control), or vehicle (n=3 control). Terminal blood samples and brains were collected 2 hr post final dose. Serial tissue sections were collected for MALDI-IMS, H&E and IHC staining from 5 distinct horizontal planes in the brain. Tissue collected between each imaging plane was homogenized for LC-MS bioanalysis. Summary of Data: In vivo BLI imaging was used to identify mice with BM and tumor presence was confirmed ex vivo using IHC. Quantitative MALDI IMS of coronal brain sections collected from mice administered niraparib showed consistent concentrations distributed throughout the brain parenchyma with locally higher concentrations detected from tumor regions. Table 1 summarizes the LC-MS bioanalysis concentrations in plasma and bulk brain homogenates and brain section concentrations detected by MALDI IMS. The estimated mean unbound brain-to-plasma partition coefficient (Kp,uu,brain) was 3.0x and 5.6x higher for niraparib compared to olaparib in control and BM mice, respectively. Conclusions: Herein, we demonstrated that niraparib has a higher brain penetration and distribution compared to olaparib in both control mice and mice with BM. Summary of Quantification Results Displayed as Total Conc. with Adjusted Free Conc. in Parentheses Compound Group Terminal Plasma Mean (ng/mL) LC-MS Bulk Brain Homogenate Mean (ng/g) MALDI IMS Brain Section Mean (ng/g) Kp,uu Brain Niraparib Control 3847 (769) 658 (111) 532 (89) 0.18 Niraparib BM 2535 (507) 543 (91) 473 (80) 0.14 Niraparib Vehicle BLQ BLQ Olaparib Control 226 (68) 6 (2) BLQ 0.06 Olaparib BM 119 (36) 5 (2) BLQ 0.03 Olaparib Vehicle BLQ BLQ Citation Format: Mark Reid Groseclose, Jeremy Barry, Tinamarie Skedzielewski, Gerald McDermott, Chakravarthi Balabhadrapatruni, Bill Benson, Yongle Pang, David K. Lim, Hoang Tran, Mike Ringenberg, Keyur Gada, Amine Aziez, Elaine Paul, Hasan Alsaid. Differentiation of niraparib and olaparib brain penetration in a mouse brain metastatic tumor model. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3582.

893 Development of a Rabbit Human Glioblastoma Model for Testing of Endovascular Selective Intra-Arterial Infusion (ESIA) of Novel Stem Cell-Based Therapeutics

INTRODUCTION: Poor outcomes for glioblastoma (GBM) are partly due to the inability to deliver therapeutic agents to the tumor because of the blood brain barrier (BBB) as well as ineffective agents. We have evaluated bone marrow-derived mesenchymal stem cells (MSCs) as transport vehicles of biological therapeutics, particularly Delta-24-RGD (D24), an engineered tumor-selective oncolytic adenovirus that replicates and lyses only in human tumor cells. In mice, we have shown that MSCs loaded with D24 (MSCs-D24) home to GBMs after intra-arterial (IA) carotid infusion, resulting in widespread distribution in the tumor and oncolysis. Intravenous infusion is ineffective, rendering IA delivery the only effective systemic option. To understand the applicability of IA infusions of MSCs-D24 requires a large animal, human brain tumor model recapitulating the challenges of clinical use. METHODS: Rabbits underwent stereotactic xenoimplantation of human GBM cell lines. Tumor creation was confirmed on magnetic resonance imaging (MRI), histologic and immunohistochemistry analysis. Selective internal carotid artery MSCs-D24 infusion ipsilateral to the tumor was performed assess efficacy and safety. RESULTS: We report on successful xenoimplantation of human glioblastoma cell lines (U87, GSC17, and GSC8-11) in 28 immunosuppressed rabbits using Mycophenolate Mofetil, Dexamethasone, and Tacrolimus. The implanted rabbits were followed for 35 days prior to tumor assessment with MRI, angiography, and histological analysis. On MRI, the tumors were hyperintense on T2-weighted image and enhanced (evidence of BBB breakdown). On histological analysis, tumors showed phenotypic traits of human GBM and display varying levels of vascularity, an important feature for testing IA therapy. Selective internal carotid artery MSCs-D24 infusion was safe in the model, and MSCs-D24 homed to the implanted tumor at 24 hours. CONCLUSIONS: The intracranial immunosuppressed rabbit human GBM model allows testing of ESIA infusion of novel therapeutics (eg. MSCs-D24) in a clinically relevant fashion.

466 Robust Model of Microglia Replacement With Circulation-Derived Microglia-Like Cells (CDMCs) in CNS Malignancies

INTRODUCTION: Tumor-associated microglia and macrophages (TAMs) represent a main cell type of brain malignancies and demonstrate complex interactions with cancerous cells and the tumor microenvironment. These interactions have important implications for the progression and treatment of malignant central nervous system (CNS) tumors. TAMs have therefore emerged as therapeutic targets, though their potential to date has been unfulfilled. METHODS: C57BL/6 mice were preconditioned for BMT with retroorbital busulfan injections (25 mg/kg), and native microglia were depleted via PLX5622 (1200 mg/kg, chow). Following transplantation, animals underwent intracranial stereotactic injection of syngeneic cell lines of either high-grade glioma (GL261) or breast cancer metastasis (E0771). Following animal sacrifice, we used single cell RNA sequencing of CD45-positive cells to profile the transcriptomic identity of glioma tumor-associated CDMCs (TA-CDMCs). RESULTS: Lineage tracing proved high intra- and peri-tumoral chimerism of BMT-graft derived cells among CNS myeloid cells in both models two weeks after tumor cell injection, demonstrating a robust ability to modify the tumor-immune microenvironment in animal models. TA-CDMCs showed a similarly activated morphology as naÏve TAMs under immunohistochemistry. Pathway enrichment analysis revealed an upregulation of immune response pathways in TA-CDMCs compared to regular TAMs, including the overexpression of genes relevant for the regulation of T cell activation, suggesting possible modification of the glioma immune-environment following CDMC repopulation. CONCLUSIONS: The present study offered a robust proof-of-concept that highly efficient TAM replacement could be achieved in orthotopic murine brain tumor models. Additionally, it appears that replaced CDMCs retain unique transcriptional patterns in the tumor-immune microenvironment, with the upregulation of several key immune response pathways. These efforts may represent a novel route of tumor-directed immunotherapy and offer exciting opportunities for ex-vivo CDMC manipulation to specifically target neoplastic cells.

IGFBP5 is an ROR1 ligand promoting glioblastoma invasion via ROR1/HER2-CREB signaling axis

Diffuse infiltration is the main reason for therapeutic resistance and recurrence in glioblastoma (GBM). However, potential targeted therapies for GBM stem-like cell (GSC) which is responsible for GBM invasion are limited. Herein, we report Insulin-like Growth Factor-Binding Protein 5 (IGFBP5) is a ligand for Receptor tyrosine kinase like Orphan Receptor 1 (ROR1), as a promising target for GSC invasion. Using a GSC-derived brain tumor model, GSCs were characterized into invasive or non-invasive subtypes, and RNA sequencing analysis revealed that IGFBP5 was differentially expressed between these two subtypes. GSC invasion capacity was inhibited by IGFBP5 knockdown and enhanced by IGFBP5 overexpression both in vitro and in vivo, particularly in a patient-derived xenograft model. IGFBP5 binds to ROR1 and facilitates ROR1/HER2 heterodimer formation, followed by inducing CREB-mediated ETV5 and FBXW9 expression, thereby promoting GSC invasion and tumorigenesis. Importantly, using a tumor-specific targeting and penetrating nanocapsule-mediated delivery of CRISPR/Cas9-based IGFBP5 gene editing significantly suppressed GSC invasion and downstream gene expression, and prolonged the survival of orthotopic tumor-bearing mice. Collectively, our data reveal that IGFBP5-ROR1/HER2-CREB signaling axis as a potential GBM therapeutic target.

Polio virotherapy targets the malignant glioma myeloid infiltrate with diffuse microglia activation engulfing the CNS.

Malignant gliomas commandeer dense inflammatory infiltrates with glioma-associated macrophages and microglia (GAMM) promoting immune suppression, evasion, and tumor progression. Like all cells in the mononuclear phagocytic system, GAMM constitutively express the poliovirus receptor, CD155. Besides myeloid cells, CD155 is widely upregulated in the neoplastic compartment of malignant gliomas. Intratumor treatment with the highly attenuated rhino:poliovirus chimera, PVSRIPO, yielded long-term survival with durable radiographic responses in patients with recurrent glioblastoma (Desjardins et al. New England Journal of Medicine, 2018). This scenario raises questions about the contributions of myeloid versus neoplastic cells to polio virotherapy of malignant gliomas. We investigated PVSRIPO immunotherapy in immunocompetent mouse brain tumor models with blinded, board-certified neuropathologist review, a range of neuropathological, immunohistochemical, and immunofluorescence analyses, and RNAseq of the tumor region. PVSRIPO treatment caused intense engagement of the GAMM infiltrate associated with substantial, but transient tumor regression. This was accompanied by marked microglia activation and proliferation in normal brain surrounding the tumor, in the ipsilateral hemisphere and extending into the contralateral hemisphere. There was no evidence for lytic infection of malignant cells. PVSRIPO-instigated microglia activation occurred against a backdrop of sustained innate antiviral inflammation, associated with induction of the Programmed Cell Death Ligand 1 (PD-L1) immune checkpoint on GAMM. Combining PVSRIPO with PD1/PD-L1 blockade led to durable remissions. Our work implicates GAMM as active drivers of PVSRIPO-induced antitumor inflammation and reveals profound and widespread neuroinflammatory activation of the brain-resident myeloid compartment by PVSRIPO.

Modulation of blood-brain tumor barrier for delivery of magnetic hyperthermia to brain cancer.

Glioblastoma (GBM) is the most invasive brain tumor and remains lack of effective treatment. The existence of blood-brain tumor barrier (BBTB) constitutes the greatest barrier to non-invasive delivery of therapeutic agents to tumors in the brain. Here, we propose a novel approach to specifically modulate BBTB and deliver magnetic hyperthermia in a systemic delivery mode for the treatment of GBM. BBTB modulation is achieved by targeted delivering fingolimod to brain tumor region via dual redox responsive PCL-SeSe-PEG (poly (ε-caprolactone)-diselenium-poly (ethylene glycol)) polymeric nanocarrier. As an antagonist of sphingosine 1-phosphate receptor-1 (S1P1), fingolimod potently inhibits the barrier function of BBB by blocking the binding of sphingosine 1-phosphate (S1P) to S1P1 in endothelial cells. We found that the modulated BBTB showed slight expression level of tight junction proteins, allowing efficient accumulation of zinc- and cobalt- doped iron oxide nanoclusters (ZnCoFe NCs) with enhanced magnetothermal conversion efficiency into tumor tissues through the paracellular pathway. As a result, the co-delivery of heat shock protein 70 inhibitor VER-155008 with ZnCoFe NCs could realize synergistic magnetic hyperthermia effects upon exposure to an alternating current magnetic field (ACMF) in both GL261 and U87 brain tumor models. This modulation approach brings new ideas for the treatment of central nervous system diseases that require delivery of therapeutic agents across the blood-brain barrier (BBB).

LILRB2-containing small extracellular vesicles from glioblastoma promote tumor progression by promoting the formation and expansion of myeloid-derived suppressor cells

BackgroundLeukocyte immunoglobulin-like receptor subfamily B2 (LILRB2) was reported to be an inhibitory molecule with suppressive functions. sEVs mediate communication between cancer cells and other cells. However, the existence of LILRB2 on sEVs in circulation and the function of sEVs-LILRB2 are still unknown. This study aims to investigate the role of LILRB2 in GBM and determine how LILRB2 in sEVs regulates tumor immunity.MethodsLILRB2 expression in normal brain and GBM tissues was detected by immunohistochemistry, and the effect of LILRB2 on prognosis was evaluated in an orthotopic brain tumor model. Next, a subcutaneous tumor model was constructed to evaluate the function of pirb in vivo. The immune cells in the tumor sites and spleen were detected by immunofluorescence staining and flow cytometry. Then, the presence of pirb in sEVs was confirmed by WB. The percentage of immune cells after incubation with sEVs from GL261 (GL261-sEVs) or sEVs from GL261-pirb+ (GL261-sEVs-pirb) was detected by flow cytometry. Then, the effect of pirb on sEVs was evaluated by a tumor-killing assay and proliferation assay. Finally, subcutaneous tumor models were constructed to evaluate the function of pirb on sEVs.ResultsLILRB2 was overexpressed in human GBM tissue and was closely related to an immunosuppressive TME in GBM. Then, a protumor ability of LILRB2 was observed in subcutaneous tumor models, which was related to lower CD8 + T cells and higher MDSCs (myeloid-derived suppressor cells) in the tumor and spleen compared to those of the control group. Next, we found that pirb on sEVs (sEVs-pirb) inhibits the function of CD8 + T cells by promoting the formation and expansion of MDSCs. Furthermore, the protumor function of sEVs-pirb was demonstrated in subcutaneous tumor models.ConclusionWe discovered that LILRB2/pirb can be transmitted between GBM cells via sEVs and that pirb on sEVs induces the formation and expansion of MDSCs. The induced MDSCs facilitate the formation of an immunosuppressive TME.Graphical

Improved Boron Neutron Capture Therapy Using Integrin αvβ3-Targeted Long-Retention-Type Boron Carrier in a F98 Rat Glioma Model

Integrin αvβ3 is more highly expressed in high-grade glioma cells than in normal tissues. In this study, a novel boron-10 carrier containing maleimide-functionalized closo-dodecaborate (MID), serum albumin as a drug delivery system, and cyclic arginine-glycine-aspartate (cRGD) that can target integrin αvβ3 was developed. The efficacy of boron neutron capture therapy (BNCT) targeting integrin αvβ3 in glioma cells in the brain of rats using a cRGD-functionalized MID-albumin conjugate (cRGD-MID-AC) was evaluated. F98 glioma cells exposed to boronophenylalanine (BPA), cRGD-MID-AC, and cRGD + MID were used for cellular uptake and neutron-irradiation experiments. An F98 glioma-bearing rat brain tumor model was used for biodistribution and neutron-irradiation experiments after BPA or cRGD-MID-AC administration. BNCT using cRGD-MID-AC had a sufficient cell-killing effect in vitro, similar to that with BNCT using BPA. In biodistribution experiments, cRGD-MID-AC accumulated in the brain tumor, with the highest boron concentration observed 8 h after administration. Significant differences were observed between the untreated group and BNCT using cRGD-MID-AC groups in the in vivo neutron-irradiation experiments through the log-rank test. Long-term survivors were observed only in BNCT using cRGD-MID-AC groups 8 h after intravenous administration. These findings suggest that BNCT with cRGD-MID-AC is highly selective against gliomas through a mechanism that is different from that of BNCT with BPA.

Intracranial Cannula Implantation for Serial Locoregional Chimeric Antigen Receptor (CAR) T Cell Infusions in Mice.

Pediatric CNS tumors are responsible for the majority of cancer-related deaths in children and have poor prognoses, despite advancements in chemotherapy and radiotherapy. As many tumors lack efficacious treatments, there is a crucial need to develop more promising therapeutic options, such as immunotherapies; the use of chimeric antigen receptor (CAR) T cell therapydirected against CNS tumors is of particular interest. Cell surface targets such as B7-H3, IL13RA2, and the disialoganglioside GD2 are highly expressed on the surface of several pediatric and adult CNS tumors,raising the opportunity to use CAR T cell therapy against these and other surface targets. To evaluate the repeated locoregional delivery of CAR T cells in preclinical murine models, an indwelling catheter system that recapitulates indwelling catheters currently being used in human clinical trials was established. Unlike stereotactic delivery, the indwelling catheter system allows for repeated dosing without the use of multiple surgeries. This protocol describes the intratumoral placement of a fixed guide cannula that has been used to successfully test serial CAR T cell infusions in orthotopic murine models of pediatric brain tumors. Following orthotopic injection and engraftment of the tumor cells in mice, intratumoral placement of a fixed guide cannula is completed on a stereotactic apparatus and secured with screws and acrylic resin. Treatment cannulas are then inserted through the fixed guide cannula for repeated CAR T cell delivery. Stereotactic placement of the guide cannula can be adjusted to deliver CAR T cells directly into the lateral ventricle or other locations in the brain. This platform offers a reliable mechanism for the preclinical testing of repeated intracranial infusions of CAR T cells and other novel therapeutics for these devastating pediatric tumors.

Translational Orthotopic Models of Glioblastoma Multiforme.

Genetically engineered mouse (GEM) models for human glioblastoma multiforme (GBM) are critical to understanding the development and progression of brain tumors. Unlike xenograft tumors, in GEMs, tumors arise in the native microenvironment in an immunocompetent mouse. However, the use of GBM GEMs in preclinical treatment studies is challenging due to long tumor latencies, heterogeneity in neoplasm frequency, and the timing of advanced grade tumor development. Mice induced via intracranial orthotopic injection are more tractable for preclinical studies, and retain features of the GEM tumors. We generated an orthotopic brain tumor model derived from a GEM model with Rb, Kras, and p53 aberrations (TRP), which develops GBM tumorsdisplaying linear foci of necrosis by neoplastic cells, and dense vascularization analogous to human GBM. Cells derived from GEM GBM tumors are injected intracranially into wild-type, strain-matched recipient mice and reproduce grade IV tumors, therefore bypassing the long tumor latency period in GEM mice and allowing for the creation of large and reproducible cohorts for preclinical studies. The highly proliferative, invasive, and vascular features of the TRP GEM model for GBM are recapitulated in the orthotopic tumors, and histopathology markers reflect human GBM subgroups. Tumor growth is monitored by serial MRI scans. Due to the invasive nature of the intracranial tumors in immunocompetent models, carefully following the injection procedure outlined here is essential to prevent extracranial tumor growth.

Modeling Human Brain Tumors and the Microenvironment Using Induced Pluripotent Stem Cells

Brain cancer is a group of diverse and rapidly growing malignancies that originate in the central nervous system (CNS) and have a poor prognosis. The complexity of brain structure and function makes brain cancer modeling extremely difficult, limiting pathological studies and therapeutic developments. Advancements in human pluripotent stem cell technology have opened a window of opportunity for brain cancer modeling, providing a wealth of customizable methods to simulate the disease in vitro. This is achieved with the advent of genome editing and genetic engineering technologies that can simulate germline and somatic mutations found in human brain tumors. This review investigates induced pluripotent stem cell (iPSC)-based approaches to model human brain cancer. The applications of iPSCs as renewable sources of individual brain cell types, brain organoids, blood-brain barrier (BBB), and brain tumor models are discussed. The brain tumor models reviewed are glioblastoma and medulloblastoma. The iPSC-derived isogenic cells and three-dimensional (3D) brain cancer organoids combined with patient-derived xenografts will enhance future compound screening and drug development for these deadly human brain cancers.

Transmembrane capability of DNA origami sheet enhanced by 3D configurational changes

DNA origami-engineered nanostructures are widely used in biomedical applications involving transmembrane delivery. Here, we propose a method to enhance the transmembrane capability of DNA origami sheets by changing their configuration from two-dimensional to three-dimensional. Three DNA nanostructures are designed and constructed, including the two-dimensional rectangular DNA origami sheet, the DNA tube, and the DNA tetrahedron. The latter two are the variants of the DNA origami sheet with three-dimensional morphologies achieved through one-step folding and multi-step parallel folding separately. The design feasibility and structural stability of three DNA nanostructures are confirmed by molecular dynamics simulations. The fluorescence signals of the brain tumor models demonstrate that the tubular and the tetrahedral configurational changes could dramatically increase the penetration efficiency of the original DNA origami sheet by about three and five times, respectively. Our findings provide constructive insights for further rational designs of DNA nanostructures for transmembrane delivery.

A mathematical model of brain tumor

Malignant glioma is an aggressive primary brain tumor. Due to its location, the interactions of glioma and the immune system are complex. We start this paper by proposing a simple mathematical model that describes the interaction among glioma cells, microglia and cytotoxic T lymphocytes (CTLs). The existence and stability conditions of the equilibrium points are analyzed. Numerical results showed that neither microglia nor CTLs has the ability to eradicate the tumor. As a result, we extend the model by including the chemotherapeutic agent. The model has six equilibrium points, and one of these points represents a cured state. Through local stability, we found a range of values for the infusion rate that guarantees the elimination of glioma, as well as preventing the glioma from reoccurring.

Multi-Targeted Neutron Capture Therapy Combined with an 18 kDa Translocator Protein-Targeted Boron Compound Is an Effective Strategy in a Rat Brain Tumor Model

Boron neutron capture therapy (BNCT) has been adapted to high-grade gliomas (HG); however, some gliomas are refractory to BNCT using boronophenylalanine (BPA). In this study, the feasibility of BNCT targeting the 18 kDa translocator protein (TSPO) expressed in glioblastoma and surrounding environmental cells was investigated. Three rat glioma cell lines, an F98 rat glioma bearing brain tumor model, DPA-BSTPG which is a boron-10 compound targeting TSPO, BPA, and sodium borocaptate (BSH) were used. TSPO expression was evaluated in the F98 rat glioma model. Boron uptake was assessed in three rat glioma cell lines and in the F98 rat glioma model. In vitro and in vivo neutron irradiation experiments were performed. DPA-BSTPG was efficiently taken up in vitro. The brain tumor has 16-fold higher TSPO expressions than its brain tissue. The compound biological effectiveness value of DPA-BSTPG was 8.43 to F98 rat glioma cells. The boron concentration in the tumor using DPA-BSTPG convection-enhanced delivery (CED) administration was approximately twice as high as using BPA intravenous administration. BNCT using DPA-BSTPG has significant efficacy over the untreated group. BNCT using a combination of BPA and DPA-BSTPG gained significantly longer survival times than using BPA alone. DPA-BSTPG in combination with BPA may provide the multi-targeted neutron capture therapy against HG.