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Inducible gene expression is an important tool in molecular biology research to study protein function. Most frequently, the antibiotic doxycycline is used for regulation of so-called tetracycline (Tet)-inducible systems. In contrast to stable gene overexpression, these systems allow investigation of acute and reversible effects of cellular protein induction. Recent reports have already called for caution when using Tet-inducible systems as the employed antibiotics can disturb mitochondrial function and alter cellular metabolism by interfering with mitochondrial translation. Reprogramming of energy metabolism has lately been recognized as an important emerging hallmark of cancer and is a central focus of cancer research. Therefore, the scope of this study was to systematically analyze dose-dependent metabolic effects of doxycycline on a panel of glioma cell lines with concomitant monitoring of gene expression from Tet-inducible systems. We report that doxycycline doses commonly used with inducible expression systems (0.01–1 µg/mL) substantially alter cellular metabolism: Mitochondrial protein synthesis was inhibited accompanied by reduced oxygen and increased glucose consumption. Furthermore, doxycycline protected human glioma cells from hypoxia-induced cell death. An impairment of cell growth was only detectable with higher doxycycline doses (10 µg/mL). Our findings describe settings where doxycycline exerts effects on eukaryotic cellular metabolism, limiting the employment of Tet-inducible systems.
BRAF V600E mutations occur frequently in malignant melanoma, but are rare in most malignant glioma subtypes. Besides, more benign brain tumors such as ganglioglioma, dysembryoblastic neuroepithelial tumours and supratentorial pilocytic astrocytomas, only pleomorphic xanthoastrocytomas (50-78%) and epitheloid glioblastoma (50%) regularly exhibit BRAF mutations. In the present study, we report on three patients with recurrent malignant gliomas harbouring a BRAF V600E mutation. All patients presented with markedly disseminated leptomeningeal disease at recurrence and had progressed after radiotherapy and alkylating chemotherapy. Therefore, estimated life expectancy at recurrence was a few weeks. All three patients received dabrafenib as a single agent and all showed a complete or nearly complete response. Treatment is ongoing and patients are stable for 27 months, 7 months and 3 months, respectively. One patient showed a dramatic radiologic and clinical response after one week of treatment. We were able to generate an ex vivo tumor cell culture from CSF in one patient. Treatment of this cell culture with dabrafenib resulted in reduced cell density and inhibition of ERK phosphorylation in vitro. To date, this is the first series on adult patients with BRAF-mutated malignant glioma and leptomeningeal dissemination treated with dabrafenib monotherapy. All patients showed a dramatic response with one patient showing an ongoing response for more than two years.
Introduction: The concurrent presence of both central nervous system (CNS) tumors and multiple sclerosis (MS) poses various diagnostic and therapeutic pitfalls and makes the clinical management of such patients challenging.
Methods: In this retrospective, single-center cohort study, we searched our clinical databases (2006–2019) for patients with concurrent CNS tumors and MS and described their disease courses. Age at diagnosis of the respective disease and probabilities for MS disease activity events (DAEs) with vs. without prior tumor-specific therapy were tested pairwise using t-test for dependent samples and exact binomial test.
Results: N = 16 patients with concurrent CNS tumors and MS were identified. MS diagnosis preceded the CNS oncological diagnosis by an average of 9 years (p = 0.004). More DAEs occurred in patients without prior chemotherapy (83.3%) than in patients with prior chemotherapy (16.7%; p = 0.008). This effect did not reach significance for patients with prior radiation therapy/radiosurgery (66.7% vs. 33.3%, p = 0.238). The average interval between DAEs and the last documented lymphopenia was 32.25 weeks.
Conclusions: This study describes the clinical and demographic features of patients with concurrent CNS tumors and MS and suggests several practical approaches to their clinical management. Our findings suggest that adding a disease-modifying MS therapy to the regimen of patients treated with chemotherapy is necessary only if the patient suffers from a highly active, aggressive course of MS. In view of the lack of prospective trials, individual risk assessments should remain the foundation of the decision on MS treatment in concurrent CNS tumor diseases.
Purpose: Seizures pose a significant burden in patients with primary and secondary brain tumors during the end-of-life period. A wide range of 6 to 56% of clinically observed epileptic seizures at the end of life has been reported. We aimed to analyse the incidence of epileptic seizures at the end of life in brain tumor patients more accurately using not only clinical but also electrophysiological findings.
Methods: This retrospective, single center study included brain tumor patients who died during the stay on the ward or within 7 days after discharge between 01/2015 and 08/2020. Clinical observation of seizures derived from the original medical records and EEG findings (within 45 days prior to death) were analyzed to determine the incidence of seizures in that period.
Results: Of the 68 eligible patients, 50 patients (73.5%) suffered from seizures within 45 days prior to death, of which n = 24 had a status epilepticus. The diagnosis of seizures/ status epilepticus was determined either by the presentation of clinical signs in 45 patients and if not, by the detection of a (possible) non-convulsive status epilepticus in the EEG of five patients.
Conclusion: In the presence of neurologically trained staff and with the frequent use of routine EEG, we were able to identify seizures and to distinguish status epilepticus from encephalopathy/ hypoactive delirium. We detected a higher incidence of seizures and status epilepticus at the end of life in neurooncological patients than previously reported.
Background: Cerebral radiation injury, including subacute radiation reactions and later stage radiation necrosis, is a severe side effect of brain tumor radiotherapy. A protocol of four infusions of the monoclonal antibody bevacizumab has been shown to be a highly effective treatment. However, bevacizumab is costly and can cause severe complications including thrombosis, bleeding and gastrointestinal perforations.
Methods: We performed a retrospective analysis of patients treated in our clinic for cerebral radiation injury who received only a singular treatment with bevacizumab. Single-shot was defined as a singular administration of bevacizumab without a second administration during an interval of at least 6 weeks.
Results: We identified 11 patients who had received a singular administration of bevacizumab to treat cerebral radiation injury. Prior radiation had been administered to treat gliomas (ten patients) or breast cancer brain metastases (one patient). 9 of 10 patients with available MRIs showed a marked reduction of edema at first follow-up. Discontinuation of Dexamethasone was possible in 6 patients and a significant dose reduction could be achieved in all other patients. One patient developed pulmonary artery embolism 2 months after bevacizumab administration. The median time to treatment failure of any cause was 3 months.
Conclusions: Single-shot bevacizumab therefore has meaningful activity in cerebral radiation injury, but durable control is rarely achieved. In patients where a complete protocol of four infusions with bevacizumab is not feasible due to medical contraindications or lack of reimbursement, single-shot bevacizumab treatment may be considered.
Cerebral radiation necrosis is a common complication of the radiotherapy of brain tumours that can cause significant mortality. Corticosteroids are the standard of care, but their efficacy is limited and the consequences of long-term steroid therapy are problematic, including the risk of adrenal insufficiency (AI). Off-label treatment with the vascular endothelial growth factor A antibody bevacizumab is highly effective in steroid-resistant radiation necrosis. Both the preservation of neural tissue integrity and the cessation of steroid therapy are key goals of bevacizumab treatment. However, the withdrawal of steroids may be impossible in patients who develop AI. In order to elucidate the frequency of AI in patients with cerebral radiation necrosis after treatment with corticosteroids and bevacizumab, we performed a retrospective study at our institution’s brain tumour centre. We obtained data on the tumour histology, age, duration and maximum dose of dexamethasone, radiologic response to bevacizumab, serum cortisol, and the need for hydrocortisone substitution for AI. We identified 17 patients with cerebral radiation necrosis who had received treatment with bevacizumab and had at least one available cortisol analysis. Fifteen patients (88%) had a radiologic response to bevacizumab. Five of the 17 patients (29%) fulfilled criteria for AI and required hormone substitution. Age, duration of dexamethasone treatment, and time since radiation were not statistically associated with the development of AI. In summary, despite the highly effective treatment of cerebral radiation necrosis with bevacizumab, steroids could yet not be discontinued due to the development of AI in roughly one-third of patients. Vigilance to spot the clinical and laboratory signs of AI and appropriate testing and management are, therefore, mandated.