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Purpose:To date, there are no systemic treatment options for patients with recurrent or refractory meningioma.Experimental Design:To identify effective drugs, we performed a large-scale drug screening using FDA-approved drugs on several meningioma cell lines. The impact of the top four compounds was assessed on cell viability, proliferation, colony formation, migration, and apoptosis. In addition, the antineoplastic effects of the selected drugs were validated in a heterotopic xenograft mouse model.Results:Analyses of the viability of meningioma cells treated with 119 antineoplastic FDA-approved drugs resulted in categorization into sensitive and resistant drug–response groups based on the mean IC50 values and peak serum concentrations (Cmax) in patients. Eighty drugs, including 15 alkylating agents, 14 antimetabolites, and 13 tyrosine kinase inhibitors, were classified as resistant (IC50 > Cmax). The sensitive drug–response group (n = 29, IC50 < Cmax) included RNA/protein synthesis inhibitors, proteasome inhibitors, topoisomerase, tyrosine-kinase, and partial histone deacetylase and microtubule inhibitors. The IC50 value of the four most effective compounds (carfilzomib, omacetaxine, ixabepilone, and romidepsin) ranged from 0.12 to 9.5 nmol/L. Most of them caused cell-cycle arrest in the G2–M-phase and induced apoptosis. Furthermore, all drugs except romidepsin significantly inhibited tumor growth in vivo. The strongest antineoplastic effect was observed for ixabepilone, which reduced tumor volume by 86%.Conclusions:In summary, a large-scale drug screening provides a comprehensive insight into the anti-meningioma activities of FDA-approved drugs, and identified carfilzomib, omacetaxine, ixabepilone, and romidepsin as novel potent antineoplastic agents for the treatment of aggressive meningiomas. The most pronounced effects were observed with ixabepilone mandating for further clinical investigation.

Supplementary Figures

Drug Screening Data

Fig. S1: Workflow; Fig. S2: Representative gating strategy for TissueFAXS analysis; Fig. S3: Analysis of helper, cytotoxic and regulatory T cell infiltration and the proportion of PD-1-expressing T cells; Fig. S4: Association between the infiltration of T cells and survival; Fig. S5: Levels of tumor-infiltrating T lymphocytes (TILs) in meningiomas, separated by their localization.

Purpose:Clinically aggressive meningiomas (MGMs) are rare but treatment-resistant tumors in need for more effective therapies. Because tumor-infiltrating T lymphocytes (TILs) are essential for successful immunotherapy, we assessed TIL numbers and their activation status in primary (p-) and recurrent (r-) meningiomas and their impact on survival.Experimental Design:Presence of TILs was analyzed in 202 clinically well-annotated cases (n = 123 pMGMs and n = 79 rMGMs) focusing on higher-grade meningiomas [n = 97 World Health Organization (WHO) °II, n = 62 WHO°III]. TILs were quantified by a semiautomated analysis on whole-tissue sections stained by multicolor immunofluorescence for CD3, CD8, FOXP3, and programmed cell death protein 1 (PD-1).Results:Median T-cell infiltration accounted for 0.59% TILs per total cell count. Although there were no significant WHO°-dependent changes regarding helper (CD3+CD8−FOXP3−) and cytotoxic (CD3+CD8+FOXP3−) TILs in pMGMs, higher number of cytotoxic TILs were associated with an improved progression-free survival (PFS) independent of prognostic confounders. rMGMs were characterized by lower numbers of TILs in general, helper, and cytotoxic TILs. The additional analysis of their activation status revealed that a proportion of PD-1+CD8+ TILs within the TIL population was significantly decreased with higher WHO grade and in rMGMs. Furthermore, lower proportions of PD-1+CD8+ TILs were associated with inferior PFS in multivariate analyses, arguing for PD-1 as activation rather than exhaustion marker.Conclusions:We identified higher numbers of CD3+CD8+FOXP3− TILs and proportions of PD-1–expressing CD3+CD8+FOXP3− TILs as novel biomarkers for better survival. These findings might facilitate the selection of patients who may benefit from immunotherapy and argue in favor of an intervention in primary rather than recurrent tumors.

Supplementary Figure Legends

Suppl. Table S1: Impact of cytotoxic T-cells on patient survival; Suppl. Table S2: Impact of PD-1-expressing cytotoxic T-cells on patient survival

PURPOSE Meningiomas are the most frequent primary intracranial tumors. Patient outcome varies widely from benign to highly aggressive, ultimately fatal courses. Reliable identification of risk of progression for individual patients is of pivotal importance. However, only biomarkers for highly aggressive tumors are established ( CDKN2A/B and TERT), whereas no molecularly based stratification exists for the broad spectrum of patients with low- and intermediate-risk meningioma. METHODS DNA methylation data and copy-number information were generated for 3,031 meningiomas (2,868 patients), and mutation data for 858 samples. DNA methylation subgroups, copy-number variations (CNVs), mutations, and WHO grading were analyzed. Prediction power for outcome was assessed in a retrospective cohort of 514 patients, validated on a retrospective cohort of 184, and on a prospective cohort of 287 multicenter cases. RESULTS Both CNV- and methylation family–based subgrouping independently resulted in increased prediction accuracy of risk of recurrence compared with the WHO classification (c-indexes WHO 2016, CNV, and methylation family 0.699, 0.706, and 0.721, respectively). Merging all risk stratification approaches into an integrated molecular-morphologic score resulted in further substantial increase in accuracy (c-index 0.744). This integrated score consistently provided superior accuracy in all three cohorts, significantly outperforming WHO grading (c-index difference P = .005). Besides the overall stratification advantage, the integrated score separates more precisely for risk of progression at the diagnostically challenging interface of WHO grade 1 and grade 2 tumors (hazard ratio 4.34 [2.48-7.57] and 3.34 [1.28-8.72] retrospective and prospective validation cohorts, respectively). CONCLUSION Merging these layers of histologic and molecular data into an integrated, three-tiered score significantly improves the precision in meningioma stratification. Implementation into diagnostic routine informs clinical decision making for patients with meningioma on the basis of robust outcome prediction.

Targeting immunosuppressive and protumorigenic glioblastoma-associated macrophages and microglial cells (GAMs) holds great potential to improve patient outcomes. Although CSF1R has emerged as a promising target to reprogram anti-inflammatory M2-like GAMs, relevant treatment data on human, tumor-educated GAMs and innovative patient-derived 3D tumor organoid models to study the influence on adaptive immunity and the effectiveness of treatment in a complex and entirely autologous setting are largely lacking. We performed a comprehensive phenotypical, transcriptional and functional analysis of primary, patient-derived GAMs upon treatment with the CSF1R-targeting drugs PLX3397, BLZ945, and GW2580. The most effective reprogramming of GAMs was observed upon GW2580 treatment, which led to a downregulation of M2-related markers and signaling pathways, while M1-like markers, phagocytosis, and T-cell killing were substantially increased. Moreover, treatment of patient-derived glioblastoma organoids with GW2580 confirmed successful reprogramming together with reduced tumor cell proliferation, indicating that treatment with GW2580 could be an important pillar in the future therapy of GBM.

Patient-derived tumor organoids (TOs) generated from tumor tissues within a few days are promising new models since under optimal conditions they preserve genotype, phenotype, the tumor microenvironment and the cellular heterogeneity of the parental tumor. This exciting new technology could provide representative avatars of the patient tumor in large numbers and thus can be exploited for drug discovery and drug screening purposes more efficiently than conventional cell lines or xenografted mouse models. We established standardized TOs from fresh glioblastoma (GBM) tissue after enzymatic dissociation into single cell suspensions and seeding cells into anti-adhesive 384-well plates. Over 1000 standardized TOs were generated per patient with a success rate of over 90%. Morphologically, TOs formed after two days. Size was stable over 10 days, with a slow outgrowth in some cases. A steady increase of the ATP signal over time indicated proliferative activity in TOs. Immunofluorescent stainings for tumor cells (GFAP), immune cells (macrophages and T-cells), and extracellular matrix (Tensascin C) confirmed a strong resemblance of TOs to their corresponding parental tumor, which was further substantiated by RNA-seq and DNA-methylation. Next, automated robot-based high-throughput drug screening (aHTS) on TOs was performed using a drug library of 166 FDA-approved antineoplastic drugs. Cell viability was assessed by CellTiter-Glo3D. In total, aHTS on TOs from 11 GBM patients including two recurrent GBMs showed a strong heterogeneity of drug responses. The top ten best-performing drugs consisted of 35 compounds targeting 14 different modes of action. Proteasome and HDAC-inhibitors demonstrated the highest efficacy. Respective targets were validated by knockdown experiments in GBM cells. Altogether, our data corroborate the future use of standardized GBM TOs as patient avatars for personalized drug testing by utilizing an automated high-throughput drug screening platform to better account for inter-patient-individual drug responses.

Glioma-infiltrating myeloid cells such microglia and macrophages (GAM) are a major component of the immunosuppressive tumor microenvironment in glioblastoma (GBM). Especially their anti-inflammatory M2-like activation state might counteract efficacy of immunotherapeutic interventions by impairing effector T cell infiltration and function. Therefore, we studied the ability of the small molecule inhibitors (SMI) PLX3397, BLZ945, and GW2580 that target the M2-associated colony stimulating factor-1 receptor (CSF1R) to shape GAM phenotype towards a pro-inflammatory M1-like phenotype and how this affects the T cell compartment.Upon treatment of freshly isolated CD11b-sorted GBM patient-derived GAMs (n = 15) a decreased expression of CD163 (M2-like) and an increased expression of HLA-DR (M1-like) as well as an increased nitrite production as an indirect measure for iNOS activation (M1-like) was observed which was most pronounced for BLZ945, and GW2580. Transcriptome analysis of treated vs. untreated GAMs supported a reprogramming towards a pro-inflammatory phenotype. In addition, treatment of GAMs in a GBM patient-derived tumor organoid model confirmed a substantial decrease of CD163+ M2-polarized GAM together with a reduced number of proliferating tumor cells. Finally, treatment of patient-derived GAMs led to an increased T cell transmigration through a dense barrier of autologous tumor-derived endothelial cells and increased the ability of T cells to kill autologous tumor cells. Our results support CSF1R blockade is able to reduce the immunosuppressive and pro-tumorigenic functions of GAM substantially and thereby could enhance the effectiveness of T cell-based immunotherapy.

Meningiomas are the most frequent primary intracranial tumors. They can follow a wide clinical spectrum from benign to highly aggressive clinical course. No specific therapy exists for refractory cases or cases not amenable to resection and radiotherapy. Identification of risk of recurrence and malignant transformation for the individual patients is challenging. However, promising molecular markers and prognostic subgrouping by DNA methylation are emerging. Still, the biological underpinnings of these diagnostic subgroups are elusive, and, consequently, no novel therapeutic options arise thereof. Here we establish robust subgroups across the full landscape of meningiomas, consistent through DNA methylation, mutations, the transcriptomic, proteomic and phospho-proteomic level. Pronounced proliferative stress and DNA damage repair signals in malignant cells and in clusters exclusive to recurrent tumors are in line with their higher mitotic activity, but also provide an explanation for the accumulation of genomic instability in anaplastic meningiomas. Although homozygous deletion of CDKN2A/B is a diagnostic marker of high-grade meningioma, the expression of its gene product increased from low to non-deleted high-grade cases. Differences between subgroups in lymphocyte and myeloid cell infiltration, representing a majority of tumor mass in low-grade NF2 tumors, could be assigned to cluster-specific interaction with tumor cells. Activation to a more proinflammatory phenotype and decreased infiltration of myeloid cells in high-grade cases correlated with lower expression of CSF1, located on chromosome arm 1p, whose deletion is known as prognostic marker, with no proposed mechanism before. Our results demonstrate a robust molecular subclassification of a tumor type across multiple layers, provide insight into heterogeneous growth dynamics despite shared pathognomonic mutations, and highlight immune infiltration modulation as a novel target for meningioma therapy.

Tumor-organoids (TOs) are novel, complex three-dimensional ex vivo tissue cultures that under optimal conditions accurately reflect genotype and phenotype of the original tissue with preserved cellular heterogeneity and morphology. They may serve as a new and exciting model for studying cancer biology and directing personalized therapies. The aim of our study was to establish TOs from meningioma (MGM) and to test their usability for large-scale drug screenings. We were capable of forming several hundred TO equal in size by controlled reaggregation of freshly prepared single cell suspension of MGM tissue samples. In total, standardized TOs from 60 patients were formed, including eight grade II and three grade III MGMs. TOs reaggregated within 3 days resulting in a reducted diameter by 50%. Thereafter, TO size remained stable throughout a 14 days observation period. TOs consisted of largely viable cells, whereas dead cells were predominantly found outside of the organoid. H&E stainings confirmed the successful establishment of dense tissue-like structures. Next, we assessed the suitability and reliability of TOs for a robust large-scale drug testing by employing nine highly potent compounds, derived from a drug screening performed on several MGM cell lines. First, we tested if drug responses depend on TO size. Interestingly, drug responses to these drugs remained identical independent of their sizes. Based on a sufficient representation of low abundance cell types such as T-cells and macrophages an overall number of 25.000 cells/TO was selected for further experiments revealing FDA-approved HDAC inhibitors as highly effective drugs in most of the TOs with a mean z-AUC score of -1.33. Taken together, we developed a protocol to generate standardized TO from MGM containing low abundant cell types of the tumor microenvironment in a representative manner. Robust and reliable drug responses suggest patient-derived TOs as a novel drug testing model in meningioma research.

Treatment of aggressive meningiomas remains challenging due to a high rate of recurrence in higher-grade meningiomas, frequent subtotal resections, and the lack of effective systemic treatments. Substantial overexpression associated with a poor prognosis has been demonstrated for kinesin family member 11 (KIF11) in high-grade meningiomas. Due to anti-tumor activity for KIF11 inhibitors (KIF11i) filanesib and ispinesib in other cancer types, we sought to investigate their mode of action and efficacy for the treatment of aggressive meningiomas. Dose curve analysis of both KIF11i revealed IC50 values of less than 1 nM in anaplastic and benign meningioma cell lines. Both compounds induced G2/M arrest and subsequent subG1 increase in all cell lines. Profound induction of apoptosis was detected in the anaplastic cell lines determined by annexin V staining. KIF11i significantly inhibited meningioma growth in xenotransplanted mice by up to 83%. Furthermore, both drugs induced minor hematological side effects, which were less pronounced for filanesib. We identified substantial in vitro and in vivo anti-tumor effects of the KIF11 inhibitors filanesib and ispinesib, with filanesib demonstrating better tolerability, suggesting future use of filanesib for the treatment of aggressive meningioma.

Tumor-associated macrophages (TAMs) play an emerging role in tumor progression by creating an immunosuppressive tumor microenvironment. Therefore, we investigated TAM numbers and their activation (M1/2) in primary (p-) and recurrent (r-) meningiomas and evaluated their impact on survival. Presence of TAMs was analyzed in 195 clinically well-annotated cases (WHO°I n = 43, WHO°II n = 95, WHO°III n = 57; pMGM n = 120, rMGM n = 75). TAMs were quantified by a semiautomated analysis on whole tissue sections stained by multicolor immunofluorescence for CD68 as general TAM marker, and for CD163 and CD204 as M2 marker. CD68+ macrophages positive for either CD163 or CD204 were regarded as M2-polarized TAMs. Furthermore, concentration of 27 immune-relevant cytokines and chemokines from meningioma tissue samples (n = 46) were assessed by Luminex analysis. Median TAM infiltration accounted for 2.47% per total cell count in pMGM and 3.22% in rMGMs. Although no significant WHO°-dependent changes regarding TAM numbers were observed, high numbers of TAMs were associated with shorter progression-free survival (PFS) independent of prognostic confounding variables such as WHO, sex and age. In pMGMs, proportion of M2-polarized TAMs was significantly increased in WHO°II and WHO°III tumors compared to WHO°I (P = 0.001 and P = 0.03, respectively). Luminex data revealed a WHO°-dependent increase of IL-8, IL-10, and IL-12p70. Tissue samples containing higher numbers of TAMs demonstrated significant elevated concentrations of interleukin-1 family members (IL-1β, IL-1Ra), and G-CSF. Furthermore, upregulation of IL-1β and IL-1Ra resulted in shorter overall survival of patients (P = 0.049, P = 0.006, respectively). Taken together, we identified higher numbers of TAMs as an independent prognostic factor for shorter progression-free survival in meningioma patients. This was associated with increased levels of the interleukin-1 family members IL-1β and IL-1Ra and a shorter overall survival, indicating an important function in the tumor microenvironment.

The mainstay of treatment for progressive or recurrent meningiomas is surgery and/or radiotherapy. Patients with refractory cancer might benefit from systemic treatment options. However, to date, no effective chemotherapy is available for these patients. For this reason, novel inhibitors for the treatment of aggressive meningiomas are urgently needed. Therefore, we used our previously published Affymetrix microarray dataset (GSE74385) consisting of 62 meningiomas enriched with 28 WHO°III MGMs to screen substantially expressed genes that can be targeted by available inhibitors. For each targeted gene, three compounds were selected based on their clinical development. This filter process resulted in 107 drugs targeting 57 different genes. Most compounds were oncology-related (n = 94, 88%) with the remaining compounds being non-oncology agents (n = 13, 12%). Thereafter, a 2-stage screening strategy was employed. First, drugs were screened at a single dose (2.5 µM) in two malignant meningioma cell lines (NCH93 and IOMM-Lee) with CellTiter-Glo (Promega). Only drugs resulting in a cell viability of 50% or less of either cell line were considered for further validation. Remaining drug candidates (n = 33) exclusively belonged to the oncology-related group, consisting of 4 FDA-approved antineoplastic drugs (12%). The other drugs are currently tested in clinical trials (24% in phase III, 39% in phase II, and 24% in phase I). Drug candidates were further analyzed in a six-point dose-response scheme ranging from 0.1 nM to 10 µM in three meningioma cell lines (Ben-Men-1, NCH93, IOMM-Lee). The top 5 drugs were selected based on the lowest mean of z-transformed area under the curve. Resulting drugs and corresponding targets are: OTSSP167 (MELK), Panobinostat (HDAC), Picropodophyllin (IGF-1R), KPT-9274 (PAK4 and NAMPT), and BI-2536 (PLK1). Taken together, our drug screening approach utilized in silico data to identify potential inhibitors for the treatment of aggressive meningiomas warranting further preclinical investigation.

The discovery of the isocitrate dehydrogenase (IDH) mutation in glioma led to a paradigm shift on how we see glioma biology. Difficulties in cultivating IDH mutant glioma stem cells (IDHmut GSCs) resulted in a paucity of preclinical models in IDHmut glioma, limiting the discovery of new effective chemotherapeutic agents. To fill this gap, we used six recently developed patient-derived IDHmut GSC lines and performed a large-scale drug screening with 147 Food and Drug Administration (FDA)-approved anticancer drugs. GSCs were subjected to the test compounds for 72 h in concentrations ranging from 0.0001 to 1 &micro, M. Cell viability was assessed by CellTiterGlo and the induction of apoptosis by flow cytometry with Annexin V/propidium iodide staining. The initial screen was performed with two IDHmut GSC lines and identified seven drugs (bortezomib, carfilzomib, daunorubicin, doxorubicin, epirubicin, omacetaxine, plicamycin) with a substantial antiproliferative activity, as reflected by half maximal inhibitory concentrations (IC50) below 1 &micro, M and maximum inhibitory effects (Emax) below 25%. These findings were validated in an additional four IDHmut GSC lines. The candidate drugs, of which plicamycin and omacetaxine are known to cross the blood brain barrier, were used for subsequent cell death analyses. A significant induction of apoptosis was observed at IC50 values of the respective drugs. In summary, we were able to identify seven FDA-approved drugs that should be further taken into clinical investigations for the treatment of IDHmut gliomas.

Simple Summary The clinical management for aggressive meningiomas remains challenging due to the lack of systemic treatment options. Receptor tyrosine kinases (RTKs) are frequently overexpressed in meningiomas and are associated with poor patient survival. In this study, we evaluated the clinically approved pan-RTK inhibitor ponatinib as a novel candidate for the treatment of aggressive meningiomas. Ponatinib decreased cell viability and proliferation of meningioma cells and subsequently induced programmed cell death. Furthermore, the drug demonstrated a considerable tumor growth inhibition without causing any adverse effects in mice. Mechanistically, this was presumably caused by blocking the PDGFR signaling pathway accompanied by induction of mitochondrial dysfunction. Altogether, the multi-RTKi ponatinib may serve as a promising candidate for targeted therapy for aggressive meningiomas. Abstract To date, there is no standard-of-care systemic therapy for the treatment of aggressive meningiomas. Receptor tyrosine kinases (RTK) are frequently expressed in aggressive meningiomas and are associated with poor survival. Ponatinib is a FDA- and EMA-approved RTK inhibitor and its efficacy in meningioma has not been studied so far. Therefore, we investigated ponatinib as a potential drug candidate against meningioma. Cell viability and cell proliferation of ponatinib-treated meningioma cells were assessed using crystal violet assay, manual counting and BrdU assay. Treated meningioma cell lines were subjected to flow cytometry to evaluate the effects on cell cycle and apoptosis. Meningioma-bearing mice were treated with ponatinib to examine antitumor effects in vivo. qPCR was performed to assess the mRNA levels of tyrosine kinase receptors after ponatinib treatment. Full-length cDNA sequencing was carried out to assess differential gene expression. IC50 values of ponatinib were between 171.2 and 341.9 nM in three meningioma cell lines. Ponatinib induced G0/G1 cell cycle arrest and subsequently led to an accumulation of cells in the subG1-phase. A significant induction of apoptosis was observed in vitro. In vivo, ponatinib inhibited meningioma growth by 72.6%. Mechanistically, this was associated with downregulation of PDGFRA/B and FLT3 mRNA levels, and mitochondrial dysfunction. Taken together, ponatinib is a promising candidate for targeted therapy in the treatment of aggressive meningioma.

Currently, we are facing several challenges in the treatment of meningiomas: only subtotally removable tumors, high rate of recurrence in higher-grade meningiomas, malignancy, and lack of effective chemotherapeutic agents for aggressive or inoperable tumors. For these reasons, there is an urgent need for more successful treatments for aggressive meningiomas. Therefore, we used 147 FDA-approved antineoplastic drugs on two different meningioma cell lines, including the genetically modified cell line Ben-Men-1 (WHO°I) and the newly established anaplastic meningioma cell line NCH93 (WHO°III). The impact of the drugs on proliferation was assessed in a high-throughput 386-well format with CellTiter-Glo (Promega) and further validation was done by crystal-violet assay. Subsequent screening of 147 FDA-approved drugs resulted in the identification of potential 5 drugs, including Bortezomib, Carfilzomib, Omacetaxine, Paclitaxel, and Ponatinib. Dose-curve analysis revealed IC50 values of these drugs in the Ben-Men-1 and NCH93 cell lines as follows: Bortezomib 16.2 and 5.7 nM, Carfilzomib 4.8 and 2.6 nM, Omacetaxine and 5.0 and 8.9 nM, Paclitaxel 2.6 and 1.9 µM, and Ponatinib 278 and 206 nM. Inhibitor dosage of 10xIC50 values and higher lead to an average inhibition of Ben-Men-1 and NCH93 cells by up to 90% on day 2 (P< .001). The impact of the antineoplastic agents on the cell cycle was analyzed by flow cytometry. Percentages of sub-G1 phase were significantly elevated with increasing drug concentrations of all five tested compounds (P< .001). To assess the effects of the drugs on migration scratch assay was performed. Drug concentrations of 10xIC50 values resulted in an inhibition of migration in Ben-Men-1 cells for Bortezomib, Carfilzomib, and Omacetaxine by 49%, 30%, and 23%, respectively (P< .05). In conclusion, we identified 5 promising drugs for the treatment of aggressive meningiomas by applying a high-throughput drug screening of 147 FDA-approved antineoplastic drugs.

Purpose: Clinically aggressive meningiomas (MGMs) are rare but treatment-resistant tumors in need for more effective therapies. Because tumor-infiltrating T lymphocytes (TILs) are essential for successful immunotherapy, we assessed TIL numbers and their activation status in primary (p-) and recurrent (r-) meningiomas and their impact on survival. Experimental Design: Presence of TILs was analyzed in 202 clinically well-annotated cases (n = 123 pMGMs and n = 79 rMGMs) focusing on higher-grade meningiomas [n = 97 World Health Organization (WHO) °II, n = 62 WHO°III]. TILs were quantified by a semiautomated analysis on whole-tissue sections stained by multicolor immunofluorescence for CD3, CD8, FOXP3, and programmed cell death protein 1 (PD-1). Results: Median T-cell infiltration accounted for 0.59% TILs per total cell count. Although there were no significant WHO°-dependent changes regarding helper (CD3+CD8−FOXP3−) and cytotoxic (CD3+CD8+FOXP3−) TILs in pMGMs, higher number of cytotoxic TILs were associated with an improved progression-free survival (PFS) independent of prognostic confounders. rMGMs were characterized by lower numbers of TILs in general, helper, and cytotoxic TILs. The additional analysis of their activation status revealed that a proportion of PD-1+CD8+ TILs within the TIL population was significantly decreased with higher WHO grade and in rMGMs. Furthermore, lower proportions of PD-1+CD8+ TILs were associated with inferior PFS in multivariate analyses, arguing for PD-1 as activation rather than exhaustion marker. Conclusions: We identified higher numbers of CD3+CD8+FOXP3− TILs and proportions of PD-1–expressing CD3+CD8+FOXP3− TILs as novel biomarkers for better survival. These findings might facilitate the selection of patients who may benefit from immunotherapy and argue in favor of an intervention in primary rather than recurrent tumors.

The management of aggressive meningiomas remains challenging due to limited treatment options besides surgical removal and radiotherapy. High recurrence rates and lack of effective chemotherapies may be reasons for the unfavorable prognosis of these patients. Consequently, there is an urgent need to identify effective therapeutic agents. For this purpose, we performed a high-throughput screening utilizing a drug library consisting of 147 FDA-approved antineoplastic drugs on the anaplastic meningioma cell line NCH93 using CellTiter-Glo (Promega). Based on the lowest IC50, the top 5 drugs were selected including Bortezomib, Carfilzomib, Omacetaxine, Ixabepilone, and Romidepsin. Validation of candidate compounds was performed in Ben-Men-1 (grade I), NCH93 (grade III), and IOMM-Lee cells (grade III) using crystal violet assay. Dose-curve analysis revealed IC50 values in the lower nanomolar range for all compounds and all cell lines (0.2 – 16.2 nM). To further substantiate our findings, cell proliferation assessed by manual counting was significantly reduced by up to 90% by each candidate drug at 10xIC50 after 48 h (P < 0.001). Furthermore, cell migration was inhibited up to 60% by all candidate drugs at the respective IC50 (P < 0.05). However, colony formation was only significantly reduced by Bortezomib and Carfilzomib (P < 0.001). The impact of the drugs on cell cycle and apoptosis was analyzed by flow cytometry using Annexin V/PI staining. All candidate drugs induced cell cycle arrest at G0/G1 or G2/M phase (P < 0.001) and subsequently induced apoptosis. Among them, Bortezomib exhibited the most pronounced effect by up to 80% of apoptotic cells (P < 0.001). In summary, by utilizing a high-throughput drug screening we were able to identify Bortezomib, Carfilzomib, Omacetaxine, Ixabepilone, and Romidepsin as potent antineoplastic agents for the treatment of aggressive meningiomas.

The kinesin superfamily (KIF) members are highly conserved motor proteins, which play an important role in cellular functions including transport of vesicles and mitosis. Kinesin proteins are involved in multiple cancer types including melanoma, retinoblastoma, and glioma. Additionally, several kinesin inhibitors are available and are currently tested in clinical studies. So far, kinesin family members have not been investigated in meningiomas. As a first step, we selected differentially expressed kinesin family members from our initial gene expression array including 75 WHO°I-III meningioma for further validation by qRT-PCR. We assessed the mRNA expression levels of the kinesins KIFC1, KIF4A, KIF11, KIF14, and KIF20A in meningiomas WHO°I (n=24), °II (n=20), and °III (n=31). The mRNA levels of all investigated kinesins showed a statistically significant increase with WHO grade. High expression of KIFC1 (p=.026), KIF11 (p=.048), and KIF14 (p=.017) was associated with a shorter progression-free survival of meningioma patients. Depletion of KIF11 via two different siRNAs inhibited cell proliferation by 91% and 95% on day 3 and 5 (p

Extracellular vesicles (EVs) are considered as important mediators of intercellular communication, which carry a diverse repertoire of genetic information between cells. This feature of EVs can be used and improved to advance their therapeutic potential. We have previously shown that genetically engineered EVs carrying the suicide gene mRNA and protein-cytosine deaminase (CD) fused to uracil phosphoribosyltransferase (UPRT)-inhibited schwannoma tumor growth in vivo. To further examine whether this approach can be applied to other cancer types, we established a subcutaneous xenograft glioblastoma tumor model in mice, as glioblastoma represents the most common primary brain tumor, which is highly aggressive compared with the original schwannoma tumor model. U87-MG glioblastoma cells were implanted into the flanks of nude SCID mice, and the animals were intratumorally injected with the EVs isolated from the cells expressing EGFP or CD-UPRT. After the intraperitoneal administration of the prodrug 5-fluorocytosine, the tumor growth was assessed by regular caliper measurements. Our data revealed that the treatment with the CD-UPRT-enriched EVs significantly reduced the tumor growth in mice. Taken together, our findings suggest that EVs uploaded with therapeutic CD-UPRT mRNA/protein may be a useful tool for glioblastoma treatment.

Kinesins play an important role in many physiological functions including intracellular vesicle transport and mitosis. The emerging role of kinesins in different cancers led us to investigate the expression and functional role of kinesins in meningioma. Therefore, we re-analyzed our previous microarray dataset of benign, atypical, and anaplastic meningiomas (n = 62) and got evidence for differential expression of five kinesins (KIFC1, KIF4A, KIF11, KIF14 and KIF20A). Further validation in an extended study sample (n = 208) revealed a significant upregulation of these genes in WHO&deg, I to &deg, III meningiomas (WHO&deg, I n = 61, WHO&deg, II n = 88, and WHO&deg, III n = 59), which was most pronounced in clinically more aggressive tumors of the same WHO grade. Immunohistochemical staining confirmed a WHO grade-associated upregulated protein expression in meningioma tissues. Furthermore, high mRNA expression levels of KIFC1, KIF11, KIF14 and KIF20A were associated with shorter progression-free survival. On a functional level, knockdown of kinesins in Ben-Men-1 cells and in the newly established anaplastic meningioma cell line NCH93 resulted in a significantly inhibited tumor cell proliferation upon siRNA-mediated downregulation of KIF11 in both cell lines by up to 95% and 71%, respectively. Taken together, in this study we were able to identify the prognostic and functional role of several kinesin family members of which KIF11 exhibits the most promising properties as a novel prognostic marker and therapeutic target, which may offer new treatment options for aggressive meningiomas.

KIF11 is a highly conserved motor protein, which plays an important role in cell division by separating the spindle poles. KIF11 have been reported to be involved in multiple cancer types including melanoma, retinoblastoma, and glioma. In our previous studies, we found grade-specific expression levels of KIF11 in meningioma. Higher expression of KIF11 was associated with shorter progression-free survival and siRNA mediated knockdown inhibited the proliferation of two different meningioma cell lines in vitro. KIF11 inhibitors like Filanesib and Ispinesib are available and currently tested in phase II clinical trials for treatment of multiple myeloma. We investigated their potential benefit for treating meningiomas. To evaluate the potential of Filanesib and Ispinesib on meningioma cell lines, crystal violett assay was performed. Dose-curve analysis revealed IC50 values of less than 1 nM in the benign meningioma cell line Ben-Men-1 and the anaplastic cell line NCH93. Proliferation assay showed that single shot inhibitor dosage of 10 nM and higher led to an average inhibition of Ben-Men-1 cells by 58% and 66% on day 1 and 2 for Filanesib and by 63% and 60% for Ispinesib. NCH93 cells decreased their proliferation by 63% and 84% for Filanesib and by 67% and 89% for Ispinesib (p