Abstract K + channels are important for controlling membrane potential and regulating functional properties of microglia. Whereas the inward-rectifying K + (K ir ) channel 2.1 modulates proliferation, voltage-gated K + channels (K v ) are linked to inflammatory response in mouse microglia (mMG). These channels serve as possible drug targets but little is known regarding their activity in human microglia. We used patch-clamp recording to study membrane currents of primary human microglia (hMG) and human induced pluripotent stem cell-derived microglia-like cells (hiPSC-MGL) and compared them with mMG. Unlike mMG, hMG and hiPSC-MGL exhibited K ir 2.1 currents only after LPS+IFN-γ stimulation. Interestingly, K v currents were not observed in hMG or hiPSC-MGL under any condition. While mMG had a progressively ameboid morphology after stimulation, hMG showed few morphological changes and hiPSC-MGL increased ramification. Overall, the activity of K ir 2.1 and K v channels in hMG and hiPSC-MGL differs fundamentally from mMG. Our findings highlight differences between species and underscore the need for translational approaches.

BACKGROUND:Glioblastoma (GB) is the most aggressive primary brain tumor in adults. Tumor-associated epilepsy at diagnosis (TAE) is common, yet its prognostic significance remains unclear. METHODS:We analyzed a retrospective multicenter test cohort of 855 GB patients (Aachen, Hamburg, Bielefeld) and validated findings in a prospectively collected cohort of 344 patients (Erlangen). Survival was assessed using multivariable Cox regression, propensity score matching, and interaction modeling of TAE and extent of resection (EOR). Molecular profiling included methylation-based classification, epigenetic deconvolution, and spatial transcriptomics. RESULTS:TAE was independently associated with improved survival (HR 0.81, 95% CI 0.69-0.99, P = .036, absolute survival advantage ∼4-5 months). This effect was validated in the independent cohort (C-index 0.68 (95% CI 0.62-0.74) and persisted in propensity-matched analyses (HR 0.74, 95% CI 0.56-0.96, P = .027). Interaction modeling revealed that gross total resection (GTR) improved survival in both groups but particularly in patients with TAE (EOR interaction HR 0.69, 95% CI 0.49-0.99, P = .041). In this subgroup, partial resection provided no significant advantage over biopsy, whereas patients without seizures benefited incrementally from both partial resection and GTR. Molecular analysis demonstrated enrichment of the RTK II subtype, differentiated cell states, and an inflammatory microenvironment in glioblastoma with TAE; tumors without seizures displayed neuronal and stem-like features. Functional validation using Electrogenomics showed that glioblastoma cortical slices with increased inflammatory score exhibited synchronization of action potentials characteristic for seizure-like epileptiform activity. CONCLUSIONS:TAE at diagnosis is a favorable prognostic marker in GB, defining a biologically distinct subgroup. Seizure status modifies the prognostic effect of surgical resection, underscoring the importance of GTR particularly in patients presenting with TAE.

Tumor-specific targeting remains a major obstacle for the development of precision cancer therapies. For several tumors and specifically glioblastoma (GBM), an aggressive brain tumor with poor prognosis, more effective treatments are urgently needed. Recombinant adeno-associated viruses (rAAVs), with their established clinical utility and mutational capsid plasticity, offer a promising platform for targeted delivery. We engineered and evaluated modified AAV capsids derived from the established AAV2 with HSPG-tropism knockdown and two less-characterized, tropism-reduced AAV9 variants. The epidermal growth factor receptor (EGFR), a tumor marker often overexpressed in GBM, was targeted by inserting an affibody (ZEGFR:1907). Also chlorotoxin (CLTX) was inserted, a peptide from scorpion venom reported to bind GBM. Transduction efficiencies were initially assessed with established cell lines (A431, HeLa, U251MG, MCF7). Affibody-displaying capsids exhibited EGFR-dependent transduction, with AAV9-affibody variants surpassing AAV9 wild-type. Several affibody-displaying capsids also transduced patient-derived GBM explants, as confirmed by fluorescence microscopy. These findings highlight the potential of retargeting AAV9 variants and the use of human surgical tissue samples for the initial evaluation of newly designed AAV capsids.

The role of adjuvant fractionated radiotherapy (aFRT) after gross total resection (GTR) of WHO-2 meningiomas remains unclear. We aimed to estimate the effect of aFRT on recurrence risk and survival following GTR and subtotal resection (STR). We analyzed 1452 patients with WHO-2 from our international, multicenter database (followed between 1989 and 2019). Outcomes were recurrence (10-year follow-up) and death (5-year follow-up). Risk estimates were obtained using competing risks and survival analysis. Average treatment effects were estimated by G-computation, adjusted for potential confounding by age, sex, Simpson grade, Ki-67 proliferation index, location, country group (universal healthcare or not), and year of treatment initiation. The robustness of findings was examined through sensitivity analyses. Overall, 276 of 1452 patients (19.0

Abstract Purpose The Ki-67 proliferation index (Ki-67 PI) has been associated with meningioma recurrence, yet its clinical utility remains debated. Whether Ki-67 PI provides prognostic information across subgroups defined by both WHO grade and extent of resection remains to be investigated. Methods We analyzed 5,050 patients with intracranial meningiomas from the international PERNS cohort (42 centers, diagnosed between 1989–2019) who underwent surgical resection without postoperative radiotherapy. Ki-67 PI prognostic accuracy was assessed up to 10 years postoperatively by using ROC analyses and estimating its association with the risk of recurrence. Results Results demonstrated that the prognostic value of Ki-67 PI differed by subgroups defined by WHO grade and Simpson grade. For patients with the same Simpson grade (1–3), the predictive accuracy of Ki-67 PI for 10-year recurrence risk was stronger in WHO-2 than in WHO-1. Within WHO-1 and WHO-2 meningiomas, the predictive accuracy of Ki-67 PI increased with higher Simpson grade (1–3). However, no predictive value was observed in Simpson grade 4 resections regardless of WHO grade. Conclusion These findings highlight that Ki-67 PI should be interpreted in the context of both WHO grade and extent of resection, and, if done so, may offer potential value to refine individualized surveillance strategies in meningioma patients with gross total resection in the initial 10-year postoperative timeframe. Findings cannot be extrapolated beyond 10 years, which may be particularly relevant for WHO-1 tumors with low Ki-67 PI and Simpson grade 1 resection.

Recurrence risk estimates underpin meningioma research, including molecular classification and clinical trial benchmarking, yet are often based on retrospective or historical data. The aim of this study was to assess the variation of recurrence risk estimates across calendar periods, WHO classification editions, geographical settings, and healthcare systems.thetermine We analyzed 4,111 patients with primary WHO-1/-2 meningiomas from 31 centers in 15 countries (1990–2019). Recurrence was defined according to local radiological assessment. The 5- and 10-year recurrence risks were estimated using regression standardization with inverse probability of censoring weights, adjusting for key clinical, surgical, and histopathological variables. Recurrence risk estimates varied across all domains examined. More recent calendar periods were associated with higher predicted recurrence risk, particularly for WHO-2 at 5 years (e.g., ≥ 2013 vs. ≤ 2007: RR 1.60, 95

Intense efforts are employed to optimize neurosurgical resection of gliomas in different clinical scenarios. However, the level of evidence employed toward personalized treatment decisions is still moderate. Therefore, a joint task force was created by the European Association for Neurosurgical Societies (EANS) and the European Association of Neuro-Oncology (EANO) in order to provide interdisciplinary guidance on the extent of resection (EOR) in glioma surgery. This task force assessed the data on the EOR in gliomas, evaluated the level of evidence, and composed recommendations. The EOR is determined routinely by postoperative magnetic resonance imaging. Since EOR may be associated with survival and may have an impact on epilepsy, neurocognition, quality of life, neurological status, and also on planning of radiation and pharmacotherapy (evidence classes I-IV), recommendations of different levels can be made for the resection of newly diagnosed glioblastomas (level A), recurrent glioblastomas (level C), newly diagnosed (level B) and recurrent (good practice point) IDH mutant gliomas, ependymomas in children (level B) and adults (good practice point) as well as World Health Organization CNS grade 1 tumors (good practice point). We hereby report the outcome of this collaborative effort by the joint task force between EANS and EANO.

Meningiomas (MGMs) are the most common primary intracranial tumors in adults with a substantial subset exhibiting aggressive clinical behavior. Immunotherapy represents a potential alternative treatment option, even though MGMs have traditionally been considered “immunologically cold” tumors. This study explored less characterized immune cell subsets —B cells, natural killer (NK) cells, and granulocytes— and their associations with major immune cell populations as well as their prognostic implications. For this purpose, we performed tissue cytometry analysis in a clinically well-annotated multi-center cohort of 97 newly diagnosed MGMs encompassing all WHO grades (1, 2, 3) and DNA methylation classes (benign, intermediate, malignant). Resulting infiltration data were integrated with previously published data on tumor-associated macrophages (TAMs) and tumor-infiltrating T lymphocytes (TILs) to identify MGM immune ecotypes. Overall, infiltration rates of B cells, NK cells, neutrophils, and eosinophils showed lower frequencies and varied widely across tumors. Notably, we observed significantly lower numbers of B cells in MGM with losses in chromosomal arms 10q and 22q, while lower number of T cells were found in patients with a loss of chromosomal arm 1p. In addition, NK cells and eosinophils were enriched in grade 1 and benign tumors, whereas neutrophils predominated in malignant cases. Despite their relatively low abundance, elevated neutrophil frequencies turned out to be an independent of prognostic factor for poor survival. Importantly, subsequent integration of TAM and TIL data derived from the same patient cohort unraveled five distinct immune ecotypes, each displaying characteristic immune cell infiltration patterns and differential survival outcomes. Altogether, this study provides an expanded overview of various rare immune cell subtypes in MGM and demonstrates their integration into different prognostic immune ecotypes, enabling better stratification in future clinical studies.

Background:The optimal extent of resection for glioblastoma remains debated, with high-level evidence from randomized controlled trials (RCTs) notably scarce. We aimed to evaluate international surgical practices, perceived quality of evidence, and feasibility of future RCTs through an international survey of neurosurgeons. Methods:An international survey was distributed via European Organization for Research and Treatment of Cancer (EORTC), European Association of Neurosurgical Societies (EANS), Congress of Neurological Surgeons (CNS), and national societies. We used descriptive statistics to summarize surgical practices and univariate analysis and multivariate regression to identify demographic or institutional factors associated with clinical decision-making. Results:Responses were received from 328 neurosurgeons across 38 countries. Participation was predominantly from Europe (81.1%), with 12.2% from North America. Most participants (82.9%) practiced in academic centers. While 60.4% identified supramarginal resection (SMR) as the optimal surgical goal, 37.8% aim for complete resection of enhancing tumor (CRET). Overall, 90.2% viewed the evidence for CRET as strong, compared to 63.1% for SMR. Despite these views, 72.6% expressed willingness to randomize patients between CRET and SMR, while 49.4% would be willing to randomize between partial resection and biopsy, if CRET is not feasible. Despite differences in individual practice, willingness to participate in RCTs remained consistent across geographic regions. The incomplete overlap between case-based decisions and general willingness to randomize highlights the importance of case-specific nuances. A paradox was observed where perceived weak evidence correlated with lower willingness to randomize(P < .001). Conclusion:There is substantial global willingness among neurosurgeons to participate in surgical RCTs for glioblastoma. These findings provide a foundation for designing future international trials to resolve long-standing controversies regarding optimal surgical strategy for glioblastoma.

Autoantibodies against leucine-rich glioma inactivated 1 protein (LGI1) lead to limbic encephalitis, a rare neurological autoimmune disorder characterized by faciobrachial dystonic seizures and memory deficits. While animal models provide precious insights into the mechanisms of LGI1 autoantibody action, species-specific confirmation is lacking. In this study, we investigated the effects of patient-derived LGI1 monoclonal antibodies (LGI1 mAb) on CA3 pyramidal neurons using cultured ex vivo human hippocampal slices, providing a unique platform to study disease mechanisms in a homologous, clinically relevant context. Under incubation conditions, human CA3 neurons preserved their morphology, were intrinsically excitable and received spontaneous excitatory currents with large amplitudes and frequencies suggestive of "giant" AMPA receptor-mediated currents. In slices exposed to LGI1 mAb, human CA3 pyramidal neurons displayed increased action potential (AP) firing frequency, mirroring the effects observed with the Kv1.1 channel blocker dendrotoxin-K (DTX-K). This increase likely resulted from a decreased Kv1.1 channel activity at the axonal initial segment, as indicated by alterations in AP properties, including spike latency at rheobase and depolarizing ramp slope. Differences between LGI1 mAb and DTX-K effects on some AP properties suggested distinct mechanisms of action and emphasized the need for further exploration of downstream pathways. Our findings underscore the importance of species-specific confirmatory studies of disease mechanisms and give insight into possibilities and limitations of human hippocampal slice cultures as a translational model for the investigation of disease mechanisms beyond epilepsy, including the effects of pharmacological compounds and autoantibodies.

ABSTRACT Disturbances of neurovascular coupling (NVC) contribute to metabolic derailment and neurological symptoms associated with epilepsy. While postictal arterial constriction can be alleviated by inhibitors of voltage gated calcium channels (VGCCs), less is knownregarding seizure-associated electrical signals in higher-order capillaries and their role in determining pericyte tone during seizures. Here we investigated electrical signaling within the ex vivo neurovascular unit (NVU) derived from rat and human brain tissue. We focused on electrical signal transduction between pericytes and endothelial cells and the potential role of VGCCs in vasomotion. Using dye coupling and paired patch-clamp recordings, we showed that morphologically heterogeneous groups of mid-capillary pericytes build a functional syncytium with endothelial cells. Coupling was asymmetric, allowing for directed propagation of electrical signals. Regardless of their morphology, mid-capillary pericytes responded with depolarization and constriction to metabotropic receptor (GPCR) activation (by thromboxane, norepinephrine and UDP-glucose). However, depolarization via the patch pipette induced neithe r Ca 2+ -influx nor constriction, suggesting lack of contribution of VGCCs to vasomotion. On inducing epileptiform activity, A2a adenosine receptors and inwardly rectifying potassium channels hyperpolarized the capillary syncytium, followed by repeated depolarizations due to seizure-associated potassium increase in the parenchyma. Thus, while mid-capillary pericytes are contractile, their tone does not rely on their membrane potential and VGCCs. However, syncytial coupling allows for transmission of seizure-associated hyper- and depolarizing signals to upstream feeding arterioles.

Abstract Background Meningiomas represent a common type of brain tumours and arise from the arachnoid cap cells which line the dural coverings of the brain. These predominantly benign tumours cause strong morbidity due to their intracranial location. Due to a lack of established pharmacological treatment approaches, surgery and radiotherapy remain the standard in clinical management of these tumours. Methods Here, we created a primary meningioma cell culture model and tested molecular compounds targeting key tumour-driving signalling pathways using cell viability assays and isobologram analysis. Results We found significant drug vulnerabilities within the meningioma-driving cell signalling network. Effective drugs included metformin, inhibitors of STAT3 and focal adhesion kinase (FAK), and the anti-inflammatory phytochemical sulforaphane, known as NRF2 pathway inducer and NFκB pathway inhibitor. Interestingly, FAK inhibitor Y15 and sulforaphane showed synergistic activity across cells of distinct meningioma patients, indicating this combination as a potential therapy approach. Conclusions Overall, we present a molecular targeting strategy for meningiomas that could pave the way for less invasive clinical management of these tumours and, as a result, help reduce patient mortality and morbidity. Metformin and sulforaphane both have FDA and EU pharmaceutical approval and thus could be repurposed promptly to establish a new meningioma therapy regimen.

OBJECTIVE:Despite advances in technical approaches, microsurgical resection remains the gold standard for treating drug-resistant mesial temporal lobe epilepsy (MTLE). However, current multicenter data on the risk of new focal neurological deficits following MTLE surgery and on factors predicting the likelihood of seizure freedom postsurgery are limited. This study aimed to evaluate the safety and efficacy of surgery by providing reliable data on the predictors of favorable postoperative outcomes. METHODS:The authors conducted a retrospective multicenter analysis across 20 epilepsy centers on 5 continents. Detailed standardized clinical data were collected, encompassing the preoperative status of patients, presurgical diagnostics, surgical techniques, complications, and neurological outcomes. Predictive factors for postoperative neurological deficits and a satisfactory response to surgery (defined as International League Against Epilepsy [ILAE] classes 1 and 2) were analyzed using a logistic regression model. Additionally, the authors assessed the relationship between neurological deficits, seizure outcomes, and neuropsychological performance. RESULTS:A total of 1167 patients were included in this study. Postoperative new neurological deficits were observed in 22.2% of cases, with new quadrantanopia being the most common (11.2%). No in-hospital mortality or 30-day mortality was recorded. Surgical revision was necessary in 4.3% of cases within the 1st year. A younger age and surgical intervention on the nondominant brain hemisphere were associated with a reduced risk of postoperative neurological deficits. After 1 year, 74.2% of patients achieved seizure outcomes classified as ILAE class 1 or 2. Known positive predictors of seizure outcomes, such as identifiable MRI lesions and a history of febrile seizures, were supported by data. Furthermore, even after adjusting for preoperative MRI findings, hemisphere dominance, occurrence of bilateral tonic-clonic seizures, age, and sex, anterior temporal lobe resection was linked to improved seizure outcomes. CONCLUSIONS:This study offers extensive multicenter data on outcomes following MTLE surgery from a large international patient cohort. The authors' analysis indicates a strong safety profile and high efficacy for epilepsy surgery in this patient group. The comprehensive breakdown of results facilitates the assessment of individual success prospects and improves informed patient counseling.

Extended Data relating to Main Figure 4/Targeting of AKT-driven subclonal progression of ALDH1A1+ cells. A, Collected source data for main Figs. 4B,C,F-H. Left, diagrams: in vitro cell confluence dynamics of paired treatment naive vs. TMZ-related experimental (TMZ→eR; BN46) or clinical (RT/TMZ; BN118, BN123, BN132) relapse patient cells. Monitoring of cell confluence by software-based cell recognition. Assay specified in Fig. 4A. Right, graphs: Readout results from the indicated cases in line, representing source data for Figs. 4B (Cell Confluence), 4C (Cell Viability), and 4H (Apoptosis). Respective assays specified in the main Figure Legends. Data as mean ± SD. p values calculated by pairwise Wilcoxon rank-sum test followed by multiple testing correction using Benjamini-Hochberg method. B, IF of ALDH1A1 and Ki67 in the BN46-donor cell tumor PDX model. Shown is an example from a TMZ+MK2206-treated mouse (OS = 148 days; low levels of cellular co-expression). Scale bar: 20 µm. C, Comparison of overall survival under the investigated treatment conditions (refer to Fig. 4J). Hazard ratio 95% confidence interval estimates and significance levels derived from Cox regression are shown.

Importance:Variations in perioperative dexamethasone dosing are common in brain metastasis resection, but their impact on patient outcomes remains unclear. Objective:To evaluate the association between perioperative dexamethasone dosing and patient outcomes, focusing on overall survival (OS) and progression-free survival (PFS). Design, Setting, and Participants:This retrospective multicenter comparative effectiveness study used data collected from January 2010 to December 2023. Patients with symptomatic brain metastases undergoing primary surgical resection at 7 neurological centers in Germany and 1 in Austria and who had complete records of perioperative dexamethasone dosing were included. Propensity score matching (PSM) was used to control for confounders. Analysis was conducted from March to June 2024. Exposures:Cumulative perioperative dexamethasone administration over 27 days, dichotomized at 122 mg using maximally selected rank statistics. Main Outcomes and Measures:The primary outcome was OS. Secondary outcomes included extracranial PFS (ecPFS) and intracranial PFS (icPFS) as well as incidence of wound revision surgery after brain metastasis resection. Hazard ratios (HRs) were calculated using Cox proportional hazards models. Results:A total of 1064 patients were included in the analysis. The median (IQR) age was 64 (56-72) years, with 489 female patients (49%) and 541 male patients (51%). Non-small cell lung cancer (NSCLC) was the most common tumor entity (564 patients [53%]), followed by breast cancer (146 patients [14%]) and melanoma (138 patients [13%]). After PSM, patients receiving cumulative dexamethasone doses less than 122 mg had a median OS of 19.1 (95% CI, 15.2-22.4) months compared with 12.0 (95% CI, 9.1-14.7) months for those receiving 122 mg or more (P = .002). Multivariable analysis showed an independent association between higher cumulative dexamethasone doses and reduced OS (HR, 1.40; 95% CI, 1.18-1.66; P < .001). Secondary analyses demonstrated consistent findings with icPFS and ecPFS and a dose-response association between cumulative dexamethasone and hazard for death. Conclusions and Relevance:In this study, higher cumulative perioperative dexamethasone was associated with reduced OS, icPFS, and ecPFS in patients undergoing brain metastasis resection. These findings suggest that stricter dosing protocols could improve outcomes. Prospective trials are warranted to confirm these associations and guide evidence-based practice.

INTRODUCTION:The rising incidence of meningiomas, coupled with the aggressive behavior observed in a subset of these tumors, presents significant clinical challenges. Accurate diagnosis and risk stratification are essential for effective patient management. AREAS COVERED:This review offers a comprehensive overview of the evolving diagnostic landscape for meningiomas. It examines the roles of MRI, CT, and PET imaging - particularly somatostatin receptor type 2 (SSTR2) PET - in tumor detection and differentiation. In addition, it discusses the integration of molecular markers into the 2021 WHO classification and highlights the potential of multiomics analyses to enhance tumor classification and prognostication. It also addresses challenges related to standardization, clinical implementation, and accessibility of these advanced diagnostic tools. A literature search was conducted using PubMed and clinicaltrials.gov to identify clinical trials exploring the use of SSTR2 PET and treatments informed by molecular diagnostic findings. EXPERT OPINION:The integration of molecular data with advanced imaging techniques offers significant promise for the development of an integrated diagnostic framework for meningiomas. This approach has the potential to improve risk stratification and support the implementation of personalized treatment strategies. However, achieving this will require extensive correlative research and the establishment of large, high-quality datasets that combine imaging, molecular, and clinical information.

Introduction:Surgery for singular brain metastases (BM) aims to improve survival by providing control of CNS disease. This concept may need to be refined against the background of recent advances in medical and radiation oncology. In particular there is a debate about the prognostic role of residual tumor. Research question:Does extent of resection influence overall- and cerebral progression-free-survival as well as functional outcome? Materials and methods:This retrospective series comprised 202 patients with single BM who underwent surgery 2015-2023. All patients underwent pre- and postoperative MR imaging. Results:Surgical indications included a tumor too large for radiosurgery (≥15.0 cm3; 42.5 %) and tissue acquisition for molecular analyses for potential therapeutic targets (21.8 %). Extent of resection was categorized as incomplete (8.4 %), questionably complete (22.3 %), and complete (69.3 %). Median residual tumor volume was only 0.12 cm3 (IQR 0.04-0.35). Complete resection was not correlated with better overall (OS) or CNS progression free survival. Complication rates and postoperative KPS did not vary significantly with resection category. Postoperative MRI revealed two cases with unilateral sigmoid sinus thrombosis in asymptomatic patients (cf. 11/16 [69.0 %] complications requiring treatment in symptomatic patients). We recorded 6.2 % major (CTCAE III-V) surgical, 5.3 % neurological, and 7.2 % medical complications. Postoperative treatment and major complications were prominent prognostic factors for OS. Conclusion:Small tumor remnants may have limited impact on survival. In the era of targeted therapies tissue acquisition for molecular analysis is an increasingly important indication for BM surgery.