Background: Glioblastoma cells assemble to a syncytial communicating network based on tumor microtubes (TMs) as ultra-long membrane protrusions. The relationship between network architecture and transcriptional profile remains poorly investigated. Drugs that interfere with this syncytial connectivity such as meclofenamate (MFA) may be highly attractive for glioblastoma therapy. Methods: In a human neocortical slice model using glioblastoma cell populations of different transcriptional signatures, three-dimensional tumor networks were reconstructed, and TM-based intercellular connectivity was mapped on the basis of two-photon imaging data. MFA was used to modulate morphological and functional connectivity; downstream effects of MFA treatment were investigated by RNA sequencing and fluorescence-activated cell sorting (FACS) analysis. Results: TM-based network morphology strongly differed between the transcriptional cellular subtypes of glioblastoma and was dependent on axon guidance molecule expression. MFA revealed both a functional and morphological demolishment of glioblastoma network architectures which was reflected by a reduction of TM-mediated intercellular cytosolic traffic as well as a breakdown of TM length. RNA sequencing confirmed a downregulation of NCAM and axon guidance molecule signaling upon MFA treatment. Loss of glioblastoma communicating networks was accompanied by a failure in the upregulation of genes that are required for DNA repair in response to temozolomide (TMZ) treatment and culminated in profound treatment response to TMZ-mediated toxicity. Conclusion: The capacity of TM formation reflects transcriptional cellular heterogeneity. MFA effectively demolishes functional and morphological TM-based syncytial network architectures. These findings might pave the way to a clinical implementation of MFA as a TM-targeted therapeutic approach.

Object: Increasing age is a known negative prognostic factor for glioblastoma. However, a multifactorial approach is necessary to achieve optimal neuro-oncological treatment. It remains unclear to what extent frailty, comorbidity burden, and obesity might exert influence on survival in geriatric glioblastoma patients. We have therefore reviewed our institutional database to assess the prognostic value of these factors in elderly glioblastoma patients. Methods: Between 2012 and 2018, patients aged ≥ 65 years with newly diagnosed glioblastoma were included in this retrospective analysis. Patients frailty was analyzed using the modified frailty index (mFI), while patients comorbidity burden was assessed according to the Charlson comorbidity index (CCI). Body mass index (BMI) was used as categorized variable. Results: A total of 110 geriatric patients with newly diagnosed glioblastoma were identified. Geriatric patients categorized as least-frail achieved a median overall survival (mOS) of 17 months, whereas most frail patients achieved a mOS of 8 months (p = 0.003). Patients with a CCI > 2 had a lower mOS of 6 months compared to patients with a lower comorbidity burden (12 months; p = 0.03). Multivariate analysis identified “subtotal resection” (p = 0.02), “unmethylated MGMT promoter status” (p = 0.03), “BMI < 30” (p = 0.04), and “frail patient (mFI ≥ 0.27)” (p = 0.03) as significant and independent predictors of 1-year mortality in geriatric patients with surgical treatment of glioblastoma (Nagelkerke's R² 0.31). Conclusions: The present study concludes that both increased frailty and comorbidity burden are significantly associated with poor OS in geriatric patients with glioblastoma. Further, the present series suggests an obesity paradox in geriatric glioblastoma patients.

Glioblastoma is the most common and aggressive primary tumor of the central nervous system with poor outcome. Current gold standard treatment is surgical resection followed by a combination of radio- and chemotherapy. Efficacy of temozolomide (TMZ), the primary chemotherapeutic agent, depends on the DNA methylation status of the O6-methylguanine DNA methyltransferase (MGMT), which has been identified as a prognostic biomarker in glioblastoma patients. Clinical studies revealed that glioblastoma patients with hypermethylated MGMT promoter have a better response to TMZ treatment and a significantly improved overall survival. In this study, we thus used the CRISPRoff genome editing tool to mediate targeted DNA methylation within the MGMT promoter region. The system carrying a CRISPR-deactivated Cas9 (dCas9) fused with a methyltransferase (Dnmt3A/3L) domain downregulated MGMT expression in TMZ-resistant human glioblastoma cell lines through targeted DNA methylation. The reduction of MGMT expression levels reversed TMZ resistance in TMZ-resistant glioblastoma cell lines resulting in TMZ induced dose-dependent cell death rates. In conclusion, we demonstrate targeted RNA-guided methylation of the MGMT promoter as a promising tool to overcome chemoresistance and improve the cytotoxic effect of TMZ in glioblastoma.

OBJECTIVE: Both pre- and postoperative seizures comprise common side effects that negatively impact patient quality of life in those suffering from intracranial meningioma. Therefore, seizure freedom represents an important outcome measure in meningioma surgery. In the current study the authors analyzed their institutional database to identify risk factors for postoperative seizure occurrence after surgical meningioma therapy in patients with preoperative symptomatic epilepsy. METHODS: Between February 2009 and April 2017, 187 patients with preoperative seizures underwent resection of supratentorial meningioma at the authors’ institution. Seizure outcome was assessed retrospectively 12 months after tumor resection according to the International League Against Epilepsy (ILAE) classification and stratified into favorable (ILAE class I) versus unfavorable (ILAE classes II–VI). A univariate and multivariate analysis was performed to identify factors influencing seizure outcome. RESULTS: Overall 169 (90%) of 187 patients with preoperative seizures achieved favorable outcome in terms of seizure freedom after meningioma resection. Multivariate analysis revealed peritumoral edema > 1 cm in maximal diameter and WHO grade II and III tumors, as well as a low extent of resection (Simpson grades III–V) as independent predictors for postoperative unfavorable seizure outcome. CONCLUSIONS: Surgery is highly effective in the treatment of seizures as common side effects of supratentorial meningioma. Furthermore, the present study identified several significant and independent risk factors for postoperative seizure occurrence, enabling one to select for high-risk patients that require special attention in clinical and surgical management.