Circulating extracellular vesicles as biomarker for diagnosis, prognosis and monitoring in glioblastoma patients.

BACKGROUND: Extracellular vesicles (EVs) obtained by noninvasive liquid biopsy from patient blood can serve as biomarkers. Here, we investigated the potential of circulating plasma EVs to serve as an indicator in the diagnosis, prognosis and treatment response of glioblastoma patients. METHODS: Plasma samples were collected from glioblastoma patients at multiple timepoints before and after surgery. EV concentrations were measured by nanoparticle tracking analysis and imaging flow cytometry. Tumor burden and edema were quantified by 3D reconstruction. EVs and tumors were further monitored in glioma-bearing mice. RESULTS: Glioblastoma patients displayed a 5.5-fold increase in circulating EVs compared to healthy donors (p < 0.0001). Patients with higher EV levels had a significantly shorter overall survival and progression-free survival than patients with lower levels, and the plasma EV concentration was an independent prognostic parameter for overall survival. EV levels correlated with the extent of peritumoral FLAIR hyperintensity but not with the size of the contrast-enhancing tumor, and similar findings were obtained in mice. Postoperatively, EV concentrations decreased rapidly back to normal levels, and the magnitude of the decline was associated with the extent of tumor resection. EV levels remained low during stable disease, but increased again upon tumor recurrence. In some patients, EV resurgence preceded the magnetic resonance imaging (MRI) detectability of tumor relapse. CONCLUSIONS: Our findings suggest that leakiness of the blood-brain barrier may primarily be responsible for the high circulating EV concentrations in glioblastoma patients. Elevated EVs reflect tumor presence, and their quantification may thus be valuable in assessing disease activity.

Doping of casted silk fibroin membranes with extracellular vesicles for regenerative therapy: a proof of concept.

Bioactive material concepts for targeted therapy have been an important research focus in regenerative medicine for years. The aim of this study was to investigate a proof-of-concept composite structure in the form of a membrane made of natural silk fibroin (SF) and extracellular vesicles (EVs) from gingival fibroblasts. EVs have multiple abilities to act on their target cell and can thus play crucial roles in both physiology and regeneration. This study used pH neutral, degradable SF-based membranes, which have excellent cell- and tissue-specific properties, as the carrier material. The characterization of the vesicles showed a size range between 120 and 180 nm and a high expression of the usual EV markers (e.g. CD9, CD63 and CD81), measured by nanoparticle tracking analysis (NTA) and single-EV flow analysis (IFCM). An initial integration of the EVs into the membrane was analyzed using scanning and transmission electron microscopy (SEM and TEM) and vesicles were successfully detected, even if they were not homogeneously distributed in the membrane. Using direct and indirect tests, the cytocompatibility of the membranes with and without EVs could be proven and showed significant differences compared to the toxic control (p < 0.05). Additionally, proliferation of L929 cells was increased on membranes functionalized with EVs (p > 0.05).

Rhizochalinin Exhibits Anticancer Activity and Synergizes with EGFR Inhibitors in Glioblastoma In Vitro Models.

Rhizochalinin (Rhiz) is a recently discovered cytotoxic sphingolipid synthesized from the marine natural compound rhizochalin. Previously, Rhiz demonstrated high in vitro and in vivo efficacy in various cancer models. Here, we report Rhiz to be highly active in human glioblastoma cell lines as well as in patient-derived glioma-stem like neurosphere models. Rhiz counteracted glioblastoma cell proliferation by inducing apoptosis, G2/M-phase cell cycle arrest, and inhibition of autophagy. Proteomic profiling followed by bioinformatic analysis suggested suppression of the Akt pathway as one of the major biological effects of Rhiz. Suppression of Akt as well as IGF-1R and MEK1/2 kinase was confirmed in Rhiz-treated GBM cells. In addition, Rhiz pretreatment resulted in a more pronounced inhibitory effect of γ-irradiation on the growth of patient-derived glioma-spheres, an effect to which the Akt inhibition may also contribute decisively. In contrast, EGFR upregulation, observed in all GBM neurospheres under Rhiz treatment, was postulated to be a possible sign of incipient resistance. In line with this, combinational therapy with EGFR-targeted tyrosine kinase inhibitors synergistically increased the efficacy of Rhiz resulting in dramatic inhibition of GBM cell viability as well as a significant reduction of neurosphere size in the case of combination with lapatinib. Preliminary in vitro data generated using a parallel artificial membrane permeability (PAMPA) assay suggested that Rhiz cannot cross the blood brain barrier and therefore alternative drug delivery methods should be used in the further in vivo studies. In conclusion, Rhiz is a promising new candidate for the treatment of human glioblastoma, which should be further developed in combination with EGFR inhibitors.

Epigenetic profiling reveals a strong association between lack of 5-ALA fluorescence and EGFR amplification in IDH-wildtype glioblastoma.

Background: 5-aminolevulinic acid (5-ALA) fluorescence-guided resection increases the percentage of complete CNS tumor resections and improves the progression-free survival of IDH-wildtype glioblastoma patients. A small subset of IDH-wildtype glioblastoma shows no 5-ALA fluorescence. An explanation for these cases is missing. In this study, we used DNA methylation profiling to further characterize non-fluorescent glioblastomas. Methods: Patients with newly diagnosed and recurrent IDH-wildtype glioblastoma that underwent surgery were analyzed. The intensity of intraoperative 5-ALA fluorescence was categorized as non-visible or visible. DNA was extracted from tumors and genome-wide DNA methylation patterns were analyzed using Illumina EPIC (850k) arrays. Furthermore, 5-ALA intensity was measured by flow cytometry on human gliomasphere lines (BT112 and BT145). Results: Of 74 included patients, 12 (16.2%) patients had a non-fluorescent glioblastoma, which were compared to 62 glioblastomas with 5-ALA fluorescence. Clinical characteristics were equally distributed between both groups. We did not find significant differences between DNA methylation subclasses and 5-ALA fluorescence (P = .24). The distribution of cells of the tumor microenvironment was not significantly different between the non-fluorescent and fluorescent tumors. Copy number variations in EGFR and simultaneous EGFRvIII expression were strongly associated with 5-ALA fluorescence since all non-fluorescent glioblastomas were EGFR-amplified (P < .01). This finding was also demonstrated in recurrent tumors. Similarly, EGFR-amplified glioblastoma cell lines showed no 5-ALA fluorescence after 24 h of incubation. Conclusions: Our study demonstrates an association between non-fluorescent IDH-wildtype glioblastomas and EGFR gene amplification which should be taken into consideration for recurrent surgery and future studies investigating EGFR-amplified gliomas.

Epigenetic neural glioblastoma enhances synaptic integration and predicts therapeutic vulnerability.

Neural-tumor interactions drive glioma growth as evidenced in preclinical models, but clinical validation is nascent. We present an epigenetically defined neural signature of glioblastoma that independently affects patients' survival. We use reference signatures of neural cells to deconvolve tumor DNA and classify samples into low- or high-neural tumors. High-neural glioblastomas exhibit hypomethylated CpG sites and upregulation of genes associated with synaptic integration. Single-cell transcriptomic analysis reveals high abundance of stem cell-like malignant cells classified as oligodendrocyte precursor and neural precursor cell-like in high-neural glioblastoma. High-neural glioblastoma cells engender neuron-to-glioma synapse formation in vitro and in vivo and show an unfavorable survival after xenografting. In patients, a high-neural signature associates with decreased survival as well as increased functional connectivity and can be detected via DNA analytes and brain-derived neurotrophic factor in plasma. Our study presents an epigenetically defined malignant neural signature in high-grade gliomas that is prognostically relevant.

Deep Characterization and Comparison of Different Retrovirus-like Particles Preloaded with CRISPR/Cas9 RNPs.

The CRISPR/Cas system has a broad range of possible medical applications, but its clinical translation has been hampered, particularly by the lack of safe and efficient vector systems mediating the short-term expression of its components. Recently, different virus-like particles (VLPs) have been introduced as promising vectors for the delivery of CRISPR/Cas genome editing components. Here, we characterized and directly compared three different types of retrovirus-based (R) VLPs, two derived from the γ-retrovirus murine leukemia virus (gRVLPs and "enhanced" egRVLPs) and one from the lentivirus human immunodeficiency virus, HIV (LVLPs). First, we unified and optimized the production of the different RVLPs. To ensure maximal comparability of the produced RVLPs, we adapted several assays, including nanoparticle tracking analysis (NTA), multi-parametric imaging flow cytometry (IFC), and Cas9-ELISA, to analyze their morphology, surface composition, size, and concentration. Next, we comparatively tested the three RVLPs targeting different genes in 293T model cells. Using identical gRNAs, we found egRVLPs to mediate the most efficient editing. Functional analyses indicated better cargo (i.e., Cas9) transfer and/or release as the underlying reason for their superior performance. Finally, we compared on- and off-target activities of the three RVLPs in human-induced pluripotent stem cells (hiPSC) exploiting the clinically relevant C-C motif chemokine receptor 5 (CCR5) as the target. Again, egRVLPs facilitated the highest, almost 100% knockout rates, importantly with minimal off-target activity. In conclusion, in direct comparison, egRVLPs were the most efficient RVLPs. Moreover, we established methods for in-depth characterization of VLPs, facilitating their validation and thus more predictable and safe application.

Clinical determinants impacting overall survival of patients with operable brain metastases from non-small cell lung cancer.

Non-small cell lung cancer (NSCLC) is currently the leading cause of cancer-related death worldwide, and the incidence of brain metastases (BM) in NSCLC patients is continuously increasing. The recent improvements of systemic treatment in NSCLC necessitate continuous updates on prognostic subgroups and factors determining overall survival (OS). In order to improve clinical decision-making in tumor boards, we investigated the clinical determinants affecting survival in patients with resectable NSCLC BM. A retrospective analysis was conducted of NSCLC patients with surgically resectable BM treated in our institution between 01/2015 and 12/2020. The relevant clinical factors affecting survival identified by univariate analysis were included in a multivariate logistic regression model. Overall, 264 patients were identified, with a mean age of 62.39 ± 9.98 years at the initial diagnosis of NSCLC BM and OS of 23.22 ± 1.71 months. The factors that significantly affected OS from the time of primary tumor diagnosis included the systemic metastatic load (median: 28.40 ± 4.82 vs. 40.93 ± 11.18 months, p = 0.021) as well as a number of BM <2 (median: 17.20 ± 2.52 vs. 32.53 ± 3.35 months, p = 0.014). When adjusted for survival time after neurosurgical intervention, a significant survival benefit was found in patients <60 years (median 16.13 ± 3.85 vs. 9.20 ± 1.39 months, p = 0.011) and, among others, patients without any concurrent systemic metastases at time of NSCLC BM diagnosis. Our data shows that the number of BM (singular/solitary), the Karnofsky Performance Status, gender, and age but not localization (infra-/supratentorial), mass-edema index or time to BM occurrence impact OS, and postsurgical survival in NSCLC BM patients. Additionally, our study shows that patients in prognostically favorable clinical subgroups an OS, which differs significantly from current statements in literature. The described clinically relevant factors may improve the understanding of the risks and the course of this disease and Faid future clinical decision making in tumor boards.

Diagnostic potential of extracellular vesicles in meningioma patients.

BACKGROUND: Extracellular vesicles (EVs) play an important role in cell-cell communication, and tumor-derived EVs circulating in patient blood can serve as biomarkers. Here, we investigated the potential role of plasma EVs in meningioma patients for tumor detection and determined whether EVs secreted by meningioma cells reflect epigenetic, genomic, and proteomic alterations of original tumors. METHODS: EV concentrations were quantified in patient plasma (n = 46). Short-term meningioma cultures were established (n = 26) and secreted EVs were isolated. Methylation and copy number profiling was performed using 850k arrays, and mutations were identified by targeted gene panel sequencing. Differential quantitative mass spectrometry was employed for proteomic analysis. RESULTS: Levels of circulating EVs were elevated in meningioma patients compared to healthy individuals, and the plasma EV concentration correlated with malignancy grade and extent of peritumoral edema. Postoperatively, EV counts dropped to normal levels, and the magnitude of the postoperative decrease was associated with extent of tumor resection. Methylation profiling of EV-DNA allowed correct tumor classification as meningioma in all investigated cases, and accurate methylation subclass assignment in almost all cases. Copy number variations present in tumors, as well as tumor-specific mutations were faithfully reflected in meningioma EV-DNA. Proteomic EV profiling did not permit original tumor identification but revealed tumor-associated proteins that could potentially be utilized to enrich meningioma EVs from biofluids. CONCLUSIONS: Elevated EV levels in meningioma patient plasma could aid in tumor diagnosis and assessment of treatment response. Meningioma EV-DNA mirrors genetic and epigenetic tumor alterations and facilitates molecular tumor classification.

MPAPASS software enables stitched multiplex, multidimensional EV repertoire analysis and a standard framework for reporting bead-based assays.

Extracellular vesicles (EVs) of various types are released or shed from all cells. EVs carry proteins and contain additional protein and nucleic acid cargo that relates to their biogenesis and cell of origin. EV cargo in liquid biopsies is of widespread interest owing to its ability to provide a retrospective snapshot of cell state at the time of EV release. For the purposes of EV cargo analysis and repertoire profiling, multiplex assays are an essential tool in multiparametric analyte studies but are still being developed for high-parameter EV protein detection. Although bead-based EV multiplex analyses offer EV profiling capabilities with conventional flow cytometers, the utilization of EV multiplex assays has been limited by the lack of software analysis tools for such assays. To facilitate robust EV repertoire studies, we developed multiplex analysis post-acquisition analysis (MPAPASS) open-source software for stitched multiplex analysis, EV database-compatible reporting, and visualization of EV repertoires.

CRISPR-to-Kill (C2K)-Employing the Bacterial Immune System to Kill Cancer Cells.

CRISPR/Cas9 was described as a bacterial immune system that uses targeted introduction of DNA double-strand breaks (DSBs) to destroy invaders. We hypothesized that we can analogously employ CRISPR/Cas9 nucleases to kill cancer cells by inducing maximal numbers of DSBs in their genome and thus triggering programmed cell death. To do so, we generated CRISPR-to-kill (C2K) lentiviral particles targeting highly repetitive Short Interspersed Nuclear Element-Alu sequences. Our Alu-specific sgRNA has more than 15,000 perfectly matched target sites within the human genome. C2K-Alu-vectors selectively killed human, but not murine cell lines. More importantly, they efficiently inhibited the growth of cancer cells including patient-derived glioblastoma cell lines resistant to high-dose irradiation. Our data provide proof-of-concept for the potential of C2K as a novel treatment strategy overcoming common resistance mechanisms. In combination with tumor-targeting approaches, the C2K system might therefore represent a promising tool for cancer gene therapy.

Cannabidiol converts NF-κB into a tumor suppressor in glioblastoma with defined antioxidative properties.

BACKGROUND: The transcription factor NF-κB drives neoplastic progression of many cancers including primary brain tumors (glioblastoma [GBM]). Precise therapeutic modulation of NF-κB activity can suppress central oncogenic signaling pathways in GBM, but clinically applicable compounds to achieve this goal have remained elusive. METHODS: In a pharmacogenomics study with a panel of transgenic glioma cells, we observed that NF-κB can be converted into a tumor suppressor by the non-psychotropic cannabinoid cannabidiol (CBD). Subsequently, we investigated the anti-tumor effects of CBD, which is used as an anticonvulsive drug (Epidiolex) in pediatric neurology, in a larger set of human primary GBM stem-like cells (hGSC). For this study, we performed pharmacological assays, gene expression profiling, biochemical, and cell-biological experiments. We validated our findings using orthotopic in vivo models and bioinformatics analysis of human GBM datasets. RESULTS: We found that CBD promotes DNA binding of the NF-κB subunit RELA and simultaneously prevents RELA phosphorylation on serine-311, a key residue that permits genetic transactivation. Strikingly, sustained DNA binding by RELA-lacking phospho-serine 311 was found to mediate hGSC cytotoxicity. Widespread sensitivity to CBD was observed in a cohort of hGSC defined by low levels of reactive oxygen species (ROS), while high ROS content in other tumors blocked CBD-induced hGSC death. Consequently, ROS levels served as a predictive biomarker for CBD-sensitive tumors. CONCLUSIONS: This evidence demonstrates how a clinically approved drug can convert NF-κB into a tumor suppressor and suggests a promising repurposing option for GBM therapy.

Genome-wide methylation profiling of glioblastoma cell-derived extracellular vesicle DNA allows tumor classification.

BACKGROUND: Genome-wide DNA methylation profiling has recently been developed into a tool that allows tumor classification in central nervous system tumors. Extracellular vesicles (EVs) are released by tumor cells and contain high molecular weight DNA, rendering EVs a potential biomarker source to identify tumor subgroups, stratify patients and monitor therapy by liquid biopsy. We investigated whether the DNA in glioblastoma cell-derived EVs reflects genome-wide tumor methylation and mutational profiles and allows noninvasive tumor subtype classification. METHODS: DNA was isolated from EVs secreted by glioblastoma cells as well as from matching cultured cells and tumors. EV-DNA was localized and quantified by direct stochastic optical reconstruction microscopy. Methylation and copy number profiling was performed using 850k arrays. Mutations were identified by targeted gene panel sequencing. Proteins were differentially quantified by mass spectrometric proteomics. RESULTS: Genome-wide methylation profiling of glioblastoma-derived EVs correctly identified the methylation class of the parental cells and original tumors, including the MGMT promoter methylation status. Tumor-specific mutations and copy number variations (CNV) were detected in EV-DNA with high accuracy. Different EV isolation techniques did not affect the methylation profiling and CNV results. DNA was present inside EVs and on the EV surface. Proteome analysis did not allow specific tumor identification or classification but identified tumor-associated proteins that could potentially be useful for enriching tumor-derived circulating EVs from biofluids. CONCLUSIONS: This study provides proof of principle that EV-DNA reflects the genome-wide methylation, CNV, and mutational status of glioblastoma cells and enables their molecular classification.

Quantification of extracellular vesicles in vitro and in vivo using sensitive bioluminescence imaging.

Extracellular vesicles (EVs) are naturally occurring nano-sized carriers that are secreted by cells and facilitate cell-to-cell communication by their unique ability to transfer biologically active cargo. Despite the pronounced increase in our understanding of EVs over the last decade, from disease pathophysiology to therapeutic drug delivery, improved molecular tools to track their therapeutic delivery are still needed. Unfortunately, the present catalogue of tools utilised for EV labelling lacks sensitivity or are not sufficiently specific. Here, we have explored the bioluminescent labelling of EVs using different luciferase enzymes tethered to CD63 to achieve a highly sensitive system for in vitro and in vivo tracking of EVs. Using tetraspanin fusions to either NanoLuc or ThermoLuc permits performing highly sensitive in vivo quantification of EVs or real-time imaging, respectively, at low cost and in a semi-high throughput manner. We find that the in vivo distribution pattern of EVs is determined by the route of injection, but that different EV subpopulations display differences in biodistribution patterns. By applying this technology for real-time non-invasive in vivo imaging of EVs, we show that their distribution to different internal organs occurs just minutes after administration.

Epigenomic programming in early fetal brain development.

Aim: To provide a comprehensive understanding of gene regulatory networks in the developing human brain and a foundation for interpreting pathogenic deregulation. Materials & methods: We generated reference epigenomes and transcriptomes of dissected brain regions and primary neural progenitor cells (NPCs) derived from cortical and ganglionic eminence tissues of four normal human fetuses. Results: Integration of these data across developmental stages revealed a directional increase in active regulatory states, transcription factor activities and gene transcription with developmental stage. Consistent with differences in their biology, NPCs derived from cortical and ganglionic eminence regions contained common, region specific, and gestational week specific regulatory states. Conclusion: We provide a high-resolution regulatory network for NPCs from different brain regions as a comprehensive reference for future studies.

Glioma escape signature and clonal development under immune pressure.

Immunotherapeutic strategies are increasingly important in neuro-oncology, and the elucidation of escape mechanisms that lead to treatment resistance is crucial. We investigated the impact of immune pressure on the clonal dynamics and immune escape signature by comparing glioma growth in immunocompetent versus immunodeficient mice. Glioma-bearing WT and Pd-1-/- mice survived significantly longer than immunodeficient Pfp-/- Rag2-/- mice. While tumors in Pfp-/- Rag2-/- mice were highly polyclonal, immunoedited tumors in WT and Pd-1-/- mice displayed reduced clonality with emergence of immune escape clones. Tumor cells in WT mice were distinguished by an IFN-γ-mediated response signature with upregulation of genes involved in immunosuppression. Tumor-infiltrating stromal cells, which include macrophages/microglia, contributed even more strongly to the immunosuppressive signature than the actual tumor cells. The identified murine immune escape signature was reflected in human patients and correlated with poor survival. In conclusion, immune pressure profoundly shapes the clonal composition and gene regulation in malignant gliomas.

Molecular profiling of an osseous metastasis in glioblastoma during checkpoint inhibition: potential mechanisms of immune escape.

Peripheral metastases of glioblastoma (GBM) are very rare despite the ability of GBM cells to pass through the blood-brain barrier and be disseminated through the peripheral blood. Here, we describe a detailed genetic and immunological characterization of a GBM metastasis in the skeleton, which occurred during anti-PD-1 immune checkpoint therapy. We performed whole genome sequencing (WGS) and 850 K methylation profiling of the primary and recurrent intracranial GBM as well as one of the bone metastases. Copy number alterations (CNA) and mutational profiles were compared to known genomic alterations in the TCGA data base. In addition, immunophenotyping of the peripheral blood was performed. The patient who was primarily diagnosed with IDH-wildtype GBM. After the resection of the first recurrence, progressive intracranial re-growth was again detected, and chemotherapy was replaced by PD-1 checkpoint inhibition, which led to a complete intracranial remission. Two months later MR-imaging revealed multiple osseous lesions. Biopsy confirmed the GBM origin of the skeleton metastases. Immunophenotyping reflected the effective activation of a peripheral T-cell response, with, however, increase of regulatory T cells during disease progression. WGS sequencing demonstrated distinct genomic alterations of the GBM metastasis, with gains along chromosomes 3 and 9 and losses along chromosome 4, 10, and 11. Mutational analysis showed mutations in potentially immunologically relevant regions. Additionally, we correlated tumour-infiltrating lymphocyte and microglia presence to the occurrence of circulating tumour cells (CTCs) in a larger cohort and found a decreased infiltration of cytotoxic T cells in patients positive for CTCs. This study exemplifies that the tumour microenvironment may dictate the response to immune checkpoint therapy. In addition, our study highlights the fact that despite an effective control of intracranial GBM, certain tumour clones have the ability to evade the tumour-specific T-cell response and cause progression even outside of the CNS.

FASN Is a Biomarker Enriched in Malignant Glioma-Derived Extracellular Vesicles.

Extracellular vesicles (EVs) are known for their important role in cancer progression and hold considerable potential as a source for tumor biomarkers. However, purification of tumor-specific EVs from patient plasma is still an urgent unmet need due to contamination by normal host cell-derived EVs, that results in compromised analytical sensitivity. Here we identified fatty acid synthase (FASN), a key lipogenic enzyme which is highly expressed in malignant glioma cells, to be elevated in CD63- and CD81-positive EVs in glioma patient plasma samples, opening vital opportunities to sort brain tumor-specific EVs.

Local Intracerebral Immunomodulation Using Interleukin-Expressing Mesenchymal Stem Cells in Glioblastoma.

PURPOSE: Mesenchymal stem cells (MSCs) show an inherent brain tumor tropism that can be exploited for targeted delivery of therapeutic genes to invasive glioma. We assessed whether a motile MSC-based local immunomodulation is able to overcome the immunosuppressive glioblastoma microenvironment and to induce an antitumor immune response. EXPERIMENTAL DESIGN: We genetically modified MSCs to coexpress high levels of IL12 and IL7 (MSCIL7/12, Apceth-301). Therapeutic efficacy was assessed in two immunocompetent orthotopic C57BL/6 glioma models using GL261 and CT2A. Immunomodulatory effects were assessed by multicolor flow cytometry to profile immune activation and exhaustion of tumor-infiltrating immune cells. Diversity of the tumor-specific immune response as analyzed using T-cell receptor sequencing. RESULTS: Intratumoral administration of MSCIL7/12 induced significant tumor growth inhibition and remission of established intracranial tumors, as demonstrated by MR imaging. Notably, up to 50% of treated mice survived long-term. Rechallenging of survivors confirmed long-lasting tumor immunity. Local treatment with MSCIL7/12 was well tolerated and led to a significant inversion of the CD4+/CD8+ T-cell ratio with an intricate, predominantly CD8+ effector T-cell-mediated antitumor response. T-cell receptor sequencing demonstrated an increased diversity of TILs in MSCIL7/12-treated mice, indicating a broader tumor-specific immune response with subsequent oligoclonal specification during generation of long-term immunity. CONCLUSIONS: Local MSC-based immunomodulation is able to efficiently alter the immunosuppressive microenvironment in glioblastoma. The long-lasting therapeutic effects warrant a rapid clinical translation of this concept and have led to planning of a phase I/II study of apceth-301 in recurrent glioblastoma.

Immune Characterization in Aneurysmal Subarachnoid Hemorrhage Reveals Distinct Monocytic Activation and Chemokine Patterns.

The pathophysiology of delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH) is incompletely understood. Intrathecal activation of inflammatory immune cells is suspected to play a major role for the induction of DCI. The aim of this study is to identify immune cell subsets and mediators involved in the pathogenesis of DCI. We prospectively collected blood and CSF from 25 patients with aSAH at early and late time points. We performed multicolor flow cytometry of peripheral blood and CSF, analyzing immune cell activation and pro-inflammatory cyto- and chemokines. In addition to the primary immune analysis, we retrospectively analyzed immune cell dynamics in the CSF of all our SAH patients. Our results show an increased monocyte infiltration secondary to aneurysm rupture in patients with DCI. Infiltrating monocytes are defined by a non-classical (CD14dim CD16+) phenotype at early stages. The infiltration is most likely triggered by the intrathecal immune activation. Here, high levels of pro-inflammatory chemokines, such as CXCL1, CXCL9, CXCL10, and CXCL11, are detected. The intrathecal cellular activation profile of monocytes was defined by upregulation of CD163 and CD86 on monocytes and a presumable later differentiation into antigen-presenting plasmacytoid dendritic cells (pDCs) and hemosiderophages. Peripheral immune activation was reflected by CD69 upregulation on T cells. Analysis of DCI prevalence, Hunt and Hess grade, and clinical outcome correlated with the degree of immune activation. We demonstrate that monocytes and T cells are activated intrathecally after aSAH and mediate a local inflammatory response which is presumably driven by chemokines. Our data shows that the distinct pattern of immune activation correlates with the prevalence of DCI, indicating a pathophysiological connection to the incidence of vasospasm.

Preclinical analysis of human mesenchymal stem cells: tumor tropism and therapeutic efficiency of local HSV-TK suicide gene therapy in glioblastoma.

Glioblastoma are highly invasive and associated with limited therapeutic options and a grim prognosis. Using stem cells to extend current therapeutic strategies by targeted drug delivery to infiltrated tumors cells is highly attractive. This study analyzes the tumor homing and therapeutic abilities of clinical grade human mesenchymal stem cells (MSCs) in an orthotopic glioblastoma mouse model. Our time course analysis demonstrated that MSCs display a rapid targeted migration to intracerebral U87 glioma xenografts growing in the contralateral hemisphere within the first 48h hours after application as assessed by histology and 7T magnetic resonance imaging. MSCs accumulated predominantly peritumorally but also infiltrated the main tumor mass and targeted distant tumor satellites while no MSCs were found in other regions of the brain. Intratumoral application of MSCs expressing herpes simplex virus thymidine kinase followed by systemic prodrug application of ganciclovir led to a significant tumor growth inhibition of 86% versus the control groups (p<0.05), which translated in a significant prolonged survival time (p<0.05). This study demonstrates that human MSCs generated according to apceth's GMP process from healthy donors are able to target and provide a significant growth inhibition in a glioblastoma model supporting a potential clinical translation.