Prolonged survival with valproic acid use in the EORTC/NCIC temozolomide trial for glioblastoma

Emerging therapeutic potential of anti-psychotic drugs in the management of human glioma: A comprehensive review

Despite numerous advancements in the last decade, human gliomas such as astrocytoma and glioblastoma multiforme have the worst prognoses among all cancers. Anti-psychotic drugs are commonly prescribed to treat mental disorders among cancer patients, and growing empirical evidence has revealed their antitumor, anti-metastatic, anti-angiogenic, anti-proliferative, chemo-preventive, and neo-adjuvant efficacies in various in vitro, in vivo, and clinical glioma models. Anti-psychotic drugs have drawn the attention of physicians and researchers owing to their beneficial effects in the prevention and treatment of gliomas. This review highlights data on the therapeutic potential of various anti-psychotic drugs as anti-proliferative, chemopreventive, and anti-angiogenic agents in various glioma models via the modulation of upstream and downstream molecular targets involved in apoptosis, autophagy, oxidative stress, inflammation, and the cell cycle in in vitro and in vivo preclinical and clinical stages among glioma patients. The ability of anti-psychotic drugs to modulate various signaling pathways and multidrug resistance-conferring proteins that enhance the efficacy of chemotherapeutic drugs with low side-effects exemplifies their great potential as neo-adjuvants and potential chemotherapeutics in single or multimodal treatment approach. Moreover, anti-psychotic drugs confer the ability to induce glioma into oligodendrocyte-like cells and neuronal-like phenotype cells with reversal of epigenetic alterations through inhibition of histone deacetylase further rationalize their use in glioma treatment. The improved understanding of anti-psychotic drugs as potential chemotherapeutic drugs or as neo-adjuvants will provide better information for their use globally as affordable, well-tolerated, and effective anticancer agents for human glioma.

Newly Diagnosed Glioblastoma: A Review on Clinical Management

Glioblastoma is an aggressive primary tumor of the central nervous system. This review will focus on clinical developments and management of newly diagnosed disease, including a discussion about the incorporation of molecular features into the classification of glioblastoma. Such advances will continue to shape our thinking about the disease and how to best manage it. With regards to treatment, the role of surgical resection, radiotherapy, chemotherapy, and tumor-treating fields will be presented. Pivotal studies defining our current standard of care will be highlighted, as will key ongoing trials that may influence our management of glioblastoma in the near future.

Withdrawal of antiepileptic drugs in patients with low grade and anaplastic glioma after long-term seizure freedom: a prospective observational study

Background

When glioma patients experience long-term seizure freedom the question arises whether antiepileptic drugs (AEDs) should be continued. As no prospective studies exist on seizure recurrence in glioma patients after AED withdrawal, we evaluated the decision-making process to withdraw AEDs in glioma patients, and seizure outcome after withdrawal.

Methods

Patients with a histologically confirmed low grade or anaplastic glioma were included. Eligible patients were seizure free ≥ 1 year from the date of last antitumor treatment, or ≥ 2 years since the last seizure when seizures occurred after the end of the last antitumor treatment. Patients and neuro-oncologists made a shared decision on the preferred AED treatment (i.e. AED withdrawal or continuation). Primary outcomes were: (1) outcome of the shared decision-making process and (2) rate of seizure recurrence.

Results

Eighty-three patients fulfilled all eligibility criteria. However, in 12/83 (14%) patients, the neuro-oncologist had serious objections to AED withdrawal. Therefore, 71/83 (86%) patients were analyzed; In 46/71 (65%) patients it was decided to withdraw AED treatment. In the withdrawal group, 26% (12/46) had seizure recurrence during follow-up. Seven of these 12 patients (58%) had tumor progression, of which three within 3 months after seizure recurrence. In the AED continuation group, 8% (2/25) of patients had seizure recurrence of which one had tumor progression.

Conclusion

In 65% of patients a shared decision was made to withdraw AEDs, of which 26% had seizure recurrence. AED withdrawal should only be considered in carefully selected patients with a presumed low risk of tumor progression.

Sequential treatment of phenethyl isothiocyanate increases sensitivity of Temozolomide resistant glioblastoma cells by decreasing expression of MGMT via NF-κB pathway

BACKGROUND

Existence of acquired or intrinsic resistance to Temozolomide (TMD) remains a point of concern in treating glioblastoma (GBM). Here we established mechanism by which Phenethyl isothiocyanate (PEITC) reverses TMD resistance in T98G cell lines both in vitro and in vivo.

METHODS

For the study TMD-resistant cell lines were generated by stepwise exposing the parental cell lines (U87 and U373) to TMD. The 50% inhibitory concentration (IC₅₀) values were established. MTT assay was done for cell survival studies, apoptosis assay by FITC Annexin V/PI staining, luciferase reporter assay for NF-κB transcription activity, cell colony survival and cell invasion assay, protein expression by western blot was done. For in vivo studies nude mouse model of GBM was established, TUNEL assay was done for apoptosis in tumor specimens.

RESULTS

We established that T98G, U87-R and U373-R showed higher NF-κB activity and exhibited higher IC₅₀ of TMD with significantly increased MGMT expression compared to untreated cells. Next, we found that PEITC suppressed proliferation of resistant GBM cells, inhibited NF-κB activity, decreased expression of MGMT and reversed the resistance in U373-R, U87-R and T98G cells. Exposure to PEITC followed by sequential treatment of TMD produced synergistic effect. In U373-R grafted xenografts mouse model PEITC suppressed cell growth and enhanced cell death.

CONCLUSION

Altogether, the present research established that combination of PEITC with TMD could enhance its clinical efficacy in resistant GBM by suppressing MGMT via inhibiting NF-κB activity.

The Analysis of Risk Factors and Survival Outcome for Chinese Patients with Epilepsy with High-Grade Glioma

OBJECTIVE

To evaluate the risk factors of tumor-related epilepsy (TRE) and the relationship between TRE and functional/survival outcomes in patients with high-grade glioma (HGG).

METHODS

The clinical data of 587 patients with HGG were retrospectively analyzed. A χ² test and logistic multiple-regression analysis were used to analyze factors associated with TRE. Logistic and Cox regression were used to analyze factors that may influence functional and survival outcomes.

RESULTS

Glioma location in temporal (odds ratio [OR], 0.439; P = 0.04) and parietal lobes (OR, 0.092; P = 0.02) were independent protective factors of preoperative epilepsy, compared with gliomas of frontal lobe. Preoperative epilepsy (OR, 9.290; P < 0.001) and dominant hemispheric location (OR, 2.616; P = 0.04) were independent risk factors of postoperative epilepsy. On univariate analysis, patients with preoperative epilepsy had longer progression-free survival (PFS) (P = 0.001) and overall survival (OS) (P < 0.001). Multivariate analysis further confirmed that preoperative epilepsy was an independent protective factor of OS (hazard ratio, 0.587; P = 0.008).

CONCLUSIONS

In patients with HGG, preoperative epilepsy is significantly associated with tumor involvement of the frontal lobe, whereas postoperative epilepsy is associated with preoperative epilepsy and dominant hemispheric location. Also, patients with HGG with preoperative epilepsy have better PFS and OS.

Recent Advances in Oncolytic Virotherapy and Immunotherapy for Glioblastoma: A Glimmer of Hope in the Search for an Effective Therapy?

To date, no targeted drugs, antibodies or combinations of chemotherapeutics have been demonstrated to be more efficient than temozolomide, or to increase efficacy of standard therapy (surgery, radiotherapy, temozolomide, steroid dexamethasone). According to recent phase III trials, standard therapy may ensure a median overall survival of up to 18⁻20 months for adult patients with newly diagnosed glioblastoma. These data explain a failure of positive non-controlled phase II trials to predict positive phase III trials and should result in revision of the landmark Stupp trial as a historical control for median overall survival in non-controlled trials. A high rate of failures in clinical trials and a lack of effective chemotherapy on the horizon fostered the development of conceptually distinct therapeutic approaches: dendritic cell/peptide immunotherapy, chimeric antigen receptor (CAR) T-cell therapy and oncolytic virotherapy. Recent early phase trials with the recombinant adenovirus DNX-2401 (Ad5-delta24-RGD), polio-rhinovirus chimera (PVSRIPO), parvovirus H-1 (ParvOryx), Toca 511 retroviral vector with 5-fluorocytosine, heat shock protein-peptide complex-96 (HSPPC-96) and dendritic cell vaccines, including DCVax-L vaccine, demonstrated that subsets of patients with glioblastoma/glioma may benefit from oncolytic virotherapy/immunotherapy (>3 years of survival after treatment). However, large controlled trials are required to prove efficacy of next-generation immunotherapeutics and oncolytic vectors.

Histone deacetylase enzymes and selective histone deacetylase inhibitors for antitumor effects and enhancement of antitumor immunity in glioblastoma

Glioblastoma multiforme (GBM), which is the most common primary central nervous system malignancy in adults, has long presented a formidable challenge to researchers and clinicians alike. Dismal 5-year survival rates of the patients with these tumors and the ability of the recurrent tumors to evade primary treatment strategies have prompted a need for alternative therapies in the treatment of GBM. Histone deacetylase (HDAC) inhibitors are currently a potential epigenetic therapy modality under investigation for use in GBM with mixed results. While these agents show promise through a variety of proposed mechanisms in the pre-clinical realm, only several of these agents have shown this same promise when translated into the clinical arena, either as monotherapy or for use in combination regimens. This review will examine the current state of use of HDAC inhibitors in GBM, the mechanistic rationale for use of HDAC inhibitors in GBM, and then examine an exciting new mechanistic revelation of certain HDAC inhibitors that promote antitumor immunity in GBM. The details of this antitumor immunity will be discussed with an emphasis on application of this antitumor immunity towards developing alternative therapies for treatment of GBM. The final section of this article will provide an overview of the current state of immunotherapy targeted specifically to GBM.

Pre-treatment or Post-treatment of Human Glioma Cells With BIX01294, the Inhibitor of Histone Methyltransferase G9a, Sensitizes Cells to Temozolomide

Glioblastoma (GBM) is a malignant, primary brain tumor, highly resistant to conventional therapies. Temozolomide (TMZ) is a first line therapeutic agent in GBM patients, however, survival of such patients is poor. High level of DNA repair protein, O⁶-methylguanine-DNA-methyltransferase (MGMT) and occurrence of glioma stem-like cells contribute to GBM resistance to the drug. Here, we explored a possibility of epigenetic reprograming of glioma cells to increase sensitivity to TMZ and restore apoptosis competence. We combined TMZ treatment with BIX01294, an inhibitor of histone methyltransferase G9a, known to be involved in cancerogenesis. Two treatment combinations were tested: BIX01294 was administered to human LN18 and U251 glioma cell cultures 48 h before TMZ or 48 h after TMZ treatment. Despite their different status of the MGMT gene promoter, there was no correlation with the response to TMZ. The analyses of cell viability, appearance of apoptotic alterations in morphology of cells and nuclei, and markers of apoptosis, such as levels of cleaved caspase 3, caspase 7 and PARP, revealed that both pre-treatment and post-treatment with BIX01294 sensitize glioma cells to TMZ. The additive effect was stronger in LN18 cells. Moreover, BIX01294 enhanced the cytotoxic effect of TMZ on glioma stem-like cells, although it was not associated with modulation of the pluripotency markers (NANOG, SOX2, CD133) expression or methylation of NANOG and SOX2 gene promoters. Accordingly, knockdown of methyltransferase G9a augments TMZ-induced cell death in LN18 cells. We found the significant increases of the LC3-II levels in LN18 cells treated with BIX01294 alone and with drug combination that suggests involvement of autophagy in enhancement of anti-tumor effect of TMZ. Treatment with BIX01294 did not affect methylation of the MGMT gene promoter. Altogether, our results suggest that G9a is a potential therapeutic target in malignant glioma and the treatment with the G9a inhibitor reprograms glioma cells and glioma stem-like cells to increase sensitivity to TMZ and restore apoptosis competence.

The survival effect of valproic acid in glioblastoma and its current trend: a systematic review and meta-analysis

Glioblastoma (GBM) can often present with seizure. Attempts have been made to associate the use of anti-epileptic medication valproic acid (VPA) in standard of care management with survival benefit in the past; however, results to date have been conflicting, and most likely subjected to historical bias. This study aimed to quantify the overall survival (OS) effect of VPA in patients with GBM based on the current literature, and identify potential trend-modifying covariates. Searches of 7 electronic databases from inception to April 2018 were conducted following the appropriate guidelines. Hazard ratios (HRs) derived from Cox proportional hazard models, and mean differences (MDs), were analyzed using the random effects model. Meta-regression was used to identify potential trend-modifying covariates. Seven retrospective cohort studies satisfied selection criteria describing 2181 primary GBM diagnoses, with 534 (24%) receiving VPA in their treatment. Overall, VPA was shown to confer a statistically significant OS advantage (HR, 0.71; 95% CI, 0.56-0.91; p < 0.01) compared to the control group by up to 2.4 months (95% CI, 1.51-3.21; p < 0.01). However, upon meta-regression, this survival advantage as inferred by HRs trended towards the null in newer studies (slope, 1.15; p = 0.02) or in studies with older participants (slope, 1.13; p = 0.02). A similar result was seen with MDs. Based on the literature to date, VPA was significantly associated with better OS in GBM patients by 2.4 months when managed by current standard of care. However, this effect was particularly emphasized among older studies or studies conducted in younger participants indicating the need to exercise caution in assuming generalizability of the pooled effect. Overall, there is considerable bias risks in the current interpretation of the literature, and larger, prospective studies are required for validating our findings.

Oscillatory brain activity associates with neuroligin-3 expression and predicts progression free survival in patients with diffuse glioma

Introduction

Diffuse gliomas have local and global effects on neurophysiological brain functioning, which are often seen as ‘passive’ consequences of the tumor. However, seminal preclinical work has shown a prominent role for neuronal activity in glioma growth: mediated by neuroligin-3 (NLGN3), increased neuronal activity causes faster glioma growth. It is unclear whether the same holds true in patients. Here, we investigate whether lower levels of oscillatory brain activity relate to lower NLGN3 expression and predict longer progression free survival (PFS) in diffuse glioma patients.

Methods

Twenty-four newly diagnosed patients with diffuse glioma underwent magnetoencephalography and subsequent tumor resection. Oscillatory brain activity was approximated by calculating broadband power (0.5–48 Hz) of the magnetoencephalography. NLGN3 expression in glioma tissue was semi-quantitatively assessed by immunohistochemistry. Peritumor and global oscillatory brain activity was then compared between different levels of NLGN3 expression with Kruskal–Wallis tests. Cox proportional hazards analyses were performed to estimate the predictive value of oscillatory brain activity for PFS.

Results

Patients with low expression of NLGN3 had lower levels of global oscillatory brain activity than patients with higher NLGN3 expression (P < 0.001). Moreover, lower peritumor (hazard ratio 2.17, P = 0.008) and global oscillatory brain activity (hazard ratio 2.10, P = 0.008) predicted longer PFS.

Conclusions

Lower levels of peritumor and global oscillatory brain activity are related to lower NLGN3 expression and longer PFS, corroborating preclinical research. This study highlights the important interplay between macroscopically measured brain activity and glioma progression, and may lead to new therapeutic interventions in diffuse glioma patients.

Electronic supplementary material

The online version of this article (10.1007/s11060-018-2967-5) contains supplementary material, which is available to authorized users.

Neurologic and Medical Management of Brain Tumors

Patients with brain tumor encounter a wide spectrum of tumor and treatment-related complications during their disease course. Tumors may serve as seizure substrates, are associated with a hypercoagulable state that results in thromboembolic complications, and may influence mood and cognition. Antitumor and supportive therapies may also have deleterious effects. Herein, we discuss major aspects of supportive care for patients with brain tumors, with attention to benefit and complications derived from the management of seizures, brain edema, venous thromboembolism, fatigue, mood alterations, and cognitive dysfunction.

Tumor-related epilepsy: epidemiology, pathogenesis and management

INTRODUCTION

Seizure is a common comorbidity in patients with brain tumor. It may be the presenting symptom or develop after the tumor diagnosis. The underlying pathophysiology of brain tumor-related epilepsy remains poorly understood.

METHODS

A comprehensive literature review of Pubmed English articles from 1980-2017 was performed to summarize current knowledge and treatment options of brain tumor-related epilepsy.

RESULTS

Multiple factors have been found to contribute to tumor-related epilepsy, including tumor type, speed of tumor growth, location, and tumor burden. The underlying pathogenesis of epilepsy is not clear but perturbations in the peri-tumoral regions, both structural and cellular communications, have been implicated.

CONCLUSIONS

Surgical and medical treatments of tumor-related epilepsy remain challenging as additional factors such as the extent of surgical resection, interactions with tumor-related oncological treatments and anti-epileptic medication related side effects need to be considered.

Molecular dissection of the valproic acid effects on glioma cells

Many glioblastoma patients suffer from seizures why they are treated with antiepileptic agents. Valproic acid (VPA) is a histone deacetylase inhibitor that apart from its anticonvulsive effects in some retrospective studies has been suggested to lead to a superior outcome of glioblastoma patients. However, the exact molecular effects of VPA treatment on glioblastoma cells have not yet been deciphered. We treated glioblastoma cells with VPA, recorded the functional effects of this treatment and performed a global and unbiased next generation sequencing study on the chromatin (ChIP) and RNA level. 1) VPA treatment clearly sensitized glioma cells to temozolomide: A protruding VPA-induced molecular feature in this context was the transcriptional upregulation/reexpression of numerous solute carrier (SLC) transporters that was also reflected by euchromatinization on the histone level and a reexpression of SLC transporters in human biopsy samples after VPA treatment. DNA repair genes were adversely reduced. 2) VPA treatment, however, also reduced cell proliferation in temozolomide-naive cells: On the molecular level in this context we observed a transcriptional upregulation/reexpression and euchromatinization of several glioblastoma relevant tumor suppressor genes and a reduction of stemness markers, while transcriptional subtype classification (mesenchymal/proneural) remained unaltered. Taken together, these findings argue for both temozolomide-dependent and -independent effects of VPA. VPA might increase the uptake of temozolomide and simultaneously lead to a less malignant glioblastoma phenotype. From a mere molecular perspective these findings might indicate a surplus value of VPA in glioblastoma therapy and could therefore contribute an additional ratio for clinical decision making.

Overview on current treatment standards in high-grade gliomas

High-grade gliomas (HGGs) are the most common primary tumors of the central nervous system, which include anaplastic gliomas (grade III) and glioblastomas (GBM, grade IV). Surgery is the mainstay of treatment in HGGs in order to achieve a histological and molecular characterization, as well as relieve neurological symptoms and improve seizure control. Combinations of some molecular factors, such as IDH 1-2 mutations, 1p/19q codeletion and MGMT methylation status, allow to classify different subtypes of gliomas and identify patients with different outcome. The SOC in HGGs consists in a combination of radiotherapy and chemotherapy with alkylating agents. Despite this therapeutic approach, tumor recurrence occurs in HGGs, and new surgical debulking, reirradiation or second-line chemotherapy are needed. Considering the poor results in terms of survival, several clinical trials have explored the efficacy and tolerability of antiangiogenic agents, targeted therapies against epidermal growth factor receptor (EGFR) and different immunotherapeutic approaches in recurrent and newly-diagnosed GBM, including immune checkpoint inhibitors (ICIs), and cell- or peptide-based vaccination with unsatisfactory results in term of disease control. In this review we describe the major updates in molecular biology of HGGs according to 2016 WHO Classification, the current management in newly-diagnosed and recurrent GBM and grade III gliomas, and the results of the most relevant clinical trials on targeted agents and immunotherapy.

Antiepileptic treatment and survival in newly diagnosed glioblastoma patients: Retrospective multicentre study in 285 Italian patients

Glioblastoma multiforme (GBM) has a dismal prognosis even with the best available treatment. Different studies have suggested a possible impact of antiepileptic drugs (AED) on survival in patients with GBM. A recent pooled analysis of prospective clinical trials in newly diagnosed GBM found no significant survival benefit in GBM patients treated with AED. We performed a retrospective study on adult patients with GBM in order to evaluate the impact of AED therapy on overall survival (OS), after adjusting for known prognostic factor (age, extent of surgery, Karnofsky performance status, radiochemotherapy). A total of 285 patients were analyzed. Of them 144 received a non-enzyme-inducing (NEIAED) and 95 an enzyme-inducing AED (EIAED). At univariate analysis the OS of patients receiving AED was not significantly different from that of patients not receiving an AED (HR 0.98, 95%CI 0.69-1.4, p = 0.925), moreover OS was not significantly different between patients receiving EIAED or NEIAED. At multivariate analysis a trend to more prolonged survival (HR 0.8, 95% CI 0.59-1.08, p = 0.15) was detected in patients treated with NEIAED. The question whether treatment with AED may increase OS in GBM patients remains unanswered and randomized extremely large controlled clinical trial would be necessary to elucidate the possible impact of AED on prognosis. In the meantime the use of AED in GBM patients, based on the presumed potential antitumour activity, is not recommended.

Treatment with 5-azacitidine delay growth of glioblastoma xenografts: a potential new treatment approach for glioblastomas

PURPOSE

Glioblastoma multiforme (GBM) is the most lethal primary brain tumor in adults. The epigenetically active ribonucleoside analog 5-azacitidine is a new therapy option that changes tumor cell chromatin, which is frequently modified by methylation and deacetylation in malignant gliomas.

METHODS

In vitro, we analyzed cell viability, cell apoptosis, and migration of human GBM cells. In vivo, we established subcutaneous and intracerebral GBM mouse models originating from U87MG, U373MG, and primary GBM cells as well as one patient-derived xenograft. Xenografts were treated with 5-azacitidine as well as valproic acid, bevacizumab, temozolomide, and phosphate buffered saline. The tumor sizes and Ki67 proliferation indices were determined. Glioma angiogenesis was examined immunohistochemically by expression analysis of endothelial cells (CD31) and pericytes (PDGFRβ).

RESULTS

In vitro, 5-azacitidine treatment significantly reduced human glioblastoma cell viability, increased cellular apoptosis, and reduced cellular migration. In vivo, 5-azacitidine significantly reduced growth in two intracerebral GBM models. Notably, this was also shown for a xenograft established from a patient surgery sample; whereas, epigenetically acting valproic acid did not show any growth reduction. Highly vascularized tumors responded to treatment, whereas low-vascularized xenografts showed no response. Furthermore, intracerebral glioblastomas treated with 5-azacitidine showed a clearly visible reduction of tumor angiogenesis and lower numbers of endothelial cells and tumor vessel pericytes.

CONCLUSIONS

Our data show significant growth inhibition as well as antiangiogenic effects in intracerebral as well as patient-derived GBM xenografts. This encourages to investigate in detail the multifactorial effects of 5-azacitidine on glioblastomas.

Combination Therapy with Sulfasalazine and Valproic Acid Promotes Human Glioblastoma Cell Death Through Imbalance of the Intracellular Oxidative Response

Glioblastoma (GBM) is the most common and aggressive malignant primary brain tumor and still lacks effective therapeutic strategies. It has already been shown that old drugs like sulfasalazine (SAS) and valproic acid (VPA) present antitumoral activities in glioma cell lines. SAS has also been associated with a decrease of intracellular glutathione (GSH) levels through a potent inhibition of xc- glutamate/cystine exchanger leading to an antioxidant deprotection. In the same way, VPA was recently identified as a histone deacetylase (HDAT) inhibitor capable of activating tumor suppression genes. As both drugs are widely used in clinical practice and their profile of adverse effects is well known, the aim of our study was to investigate the effects of the combined treatment with SAS and VPA in GBM cell lines. We observed that both drugs were able to reduce cell viability in a dose-dependent manner and the combined treatment potentiated these effects. Combined treatment also increased cell death and inhibited proliferation of GBM cells, while having no effect on human and rat cultured astrocytes. Also, we observed high protein expression of the catalytic subunit of xc- in all the examined GBM cell lines, and treatment with SAS blocked its activity and decreased intracellular GSH levels. Noteworthy, SAS but not VPA was also able to reduce the [¹⁴C]-ascorbate uptake. Together, these data indicate that SAS and VPA exhibit a substantial effect on GBM cell's death related to an intracellular oxidative response imbalance, making this combination of drugs a promising therapeutic strategy.

Outcome of cancer-related seizures in patients treated with lacosamide

OBJECTIVES

Lacosamide is an antiepileptic drug (AED), which has proven to be effective to control seizures, including acute conditions such as status epilepticus. The aim of this study is to describe the clinical experience with lacosamide in neuro-oncological patients.

MATERIALS AND METHODS

Multicenter retrospective study in patients with cancer-related seizures, who received lacosamide as an add-on therapy.

RESULTS

Forty-eight patients with benign and malignant tumors, including primary brain tumors, lymphomas, systemic cancer with central nervous system involvement, or paraneoplastic encephalitis, were included. Lacosamide was effective in the control of chronic seizures in patients with either benign or malignant tumors. The success rate was greater in malignant tumors, and drug-resistant epilepsies were more likely associated with benign tumors. Adverse events occurred in nearly 70% of patients, particularly in acute conditions and associated with the concomitant use of radio-/chemotherapy. Lacosamide-related adverse events were more likely somnolence and dizziness, which usually resolved after dose adjustment. After starting lacosamide, nearly half of the patients discontinued one of the baseline AEDs and decreased or discontinued dexamethasone. Fifteen patients with status epilepticus were treated with intravenous lacosamide, and 73% of them had their condition resolved without serious drug-related adverse events.

CONCLUSION

Lacosamide is an AED to consider in cases of cancer-related seizures. Lacosamide pharmacodynamics and pharmacokinetics allow the achievement of responder rates over 50% with no serious adverse effects, amelioration of side effects from other AEDs or radio-/chemotherapy, and no significant drug interactions. Furthermore, the intravenous formulation shows clear benefits in acute conditions such as status epilepticus.

Efficacy and safety of Levetiracetam vs. other antiepileptic drugs in Hispanic patients with glioblastoma

Epilepsy is a common symptom in patients with glioblastoma (GB). 213 patients with GB from RedLANO follow-up registry were included. All patients underwent surgery, if feasible, followed by chemoradiation based on temozolomide (Stupp platform). Information was recorded regarding demographics, seizure timing, anti-epileptic drugs (AEDs), dosage, time to next seizure, total seizures in 6 months, and main side effects of AEDs. The relationship between epilepsy treatment and overall survival (OS) was evaluated. Mean age was 53 years old and 56.8% were male. Seventy-eight patients (37%) were treated with levetiracetam (LEV), 27% were given another AED and 36% did not require any AED. Choice of AED was not associated with age (p = 0.67), performance status (p = 0.24) or anatomic tumor site (p = 0.34). Seizures and AED requirement were greater in those having primary GB (p = 0.04). After starting an AED, the mean time until next crisis was 9.9 days (SD ± 6.3), which was shorter in those receiving LEV (p = 0.03); mean number of seizures during the first 3 and 6 months were 2.9 and 4, respectively. Most patients treated with LEV (n = 46) required less than two medication adjustments compared to those treated with other AEDs (p = 0.02). Likewise, less patients exposed to LEV required a coadjuvant drug (p = 0.04). Additionally, patients receiving LEV had significantly less adverse effects compared to patients treated with another AED. OS was significantly higher in the group treated with LEV compared to other AEDs (25.5 vs. 17.9 months; p = 0.047). Patients treated with LEV had better seizure control and longer OS compared to other AEDs.

Advances in epigenetic glioblastoma therapy

Glioblastoma multiforme (GBM) is the most lethal primary brain tumor in adults despite contemporary gold-standard first-line treatment strategies. This type of tumor recurs in virtually all patients and no commonly accepted standard treatment exists for the recurrent disease. Therefore, advances in all scientific and clinical aspects of GBM are urgently needed. Epigenetic mechanisms are one of the major factors contributing to the pathogenesis of cancers, including glioblastoma. Epigenetic modulators that regulate gene expression by altering the epigenome and non-histone proteins are being exploited as therapeutic drug targets. Over the last decade, numerous preclinical and clinical studies on histone deacetylase (HDAC) inhibitors have shown promising results in various cancers. This article provides an overview of the anticancer mechanisms of HDAC inhibitors and the role of HDAC isoforms in GBM. We also summarize current knowledge on HDAC inhibitors on the basis of preclinical studies and emerging clinical data.

Valproic acid inhibits glioblastoma multiforme cell growth via paraoxonase 2 expression

We studied the potential mechanisms of valproic acid (VPA) in the treatment of glioblastoma multiforme (GBM). Using the human U87, GBM8401, and DBTRG-05MG GBM-derived cell lines, VPA at concentrations of 5 to 20 mM induced G2/M cell cycle arrest and increased the production of reactive oxygen species (ROS). Stress-related molecules such as paraoxonase 2 (PON2), cyclin B1, cdc2, and Bcl-xL were downregulated, but p27, p21 and Bim were upregulated by VPA treatment. VPA response element on the PON2 promoter was localized at position -400/−1. PON2 protein expression was increased in GBM cells compared with normal brain tissue and there was a negative correlation between the expression of PON2 and Bim. These findings were confirmed by the public Bredel GBM microarray (Gene Expression Omnibus accession: GSE2223) and the Cancer Genome Atlas GBM microarray datasets. Overexpression of PON2 in GBM cells significantly decreased intracellular ROS levels, and PON2 expression was decreased after VPA stimulation compared with controls. Bim expression was significantly induced by VPA in GBM cells with PON2 silencing. These observations were further shown in the subcutaneous GBM8401 cell xenograft of BALB/c nude mice. Our results suggest that VPA reduces PON2 expression in GBM cells, which in turn increases ROS production and induces Bim production that inhibits cancer progression via the PON2–Bim cascade.

Histone Deacetylase Inhibitors as Anticancer Drugs

Carcinogenesis cannot be explained only by genetic alterations, but also involves epigenetic processes. Modification of histones by acetylation plays a key role in epigenetic regulation of gene expression and is controlled by the balance between histone deacetylases (HDAC) and histone acetyltransferases (HAT). HDAC inhibitors induce cancer cell cycle arrest, differentiation and cell death, reduce angiogenesis and modulate immune response. Mechanisms of anticancer effects of HDAC inhibitors are not uniform; they may be different and depend on the cancer type, HDAC inhibitors, doses, etc. HDAC inhibitors seem to be promising anti-cancer drugs particularly in the combination with other anti-cancer drugs and/or radiotherapy. HDAC inhibitors vorinostat, romidepsin and belinostat have been approved for some T-cell lymphoma and panobinostat for multiple myeloma. Other HDAC inhibitors are in clinical trials for the treatment of hematological and solid malignancies. The results of such studies are promising but further larger studies are needed. Because of the reversibility of epigenetic changes during cancer development, the potency of epigenetic therapies seems to be of great importance. Here, we summarize the data on different classes of HDAC inhibitors, mechanisms of their actions and discuss novel results of preclinical and clinical studies, including the combination with other therapeutic modalities.

Prevention and management of postoperative seizures in neuro-oncology

INTRODUCTION

Epilepsy related to brain tumors is often difficult to treat and may impact the quality of life. We performed a review of current recommendations for the prevention of postoperative seizures and optimizing the anti-epileptic treatment.

MATERIAL AND METHODS

Based on studies performed since 2000 we conducted the review by (1) analyzing the incidence of tumoral epilepsy and mechanisms of epileptogenicity; (2) describing the current medical and surgical strategy according to oncologic treatments; (3) discussing the management of postoperative seizures; (4) considering the drug withdrawal after oncologic therapy.

RESULTS

Epilepsy related to supra-tentorial brain tumors is frequent (40-60%) especially in low-grade gliomas, glioneuronal tumors, fronto-temporal and eloquent cortex locations. Seizures can occur as a presenting symptom or during the course of the tumor, including after surgery and oncological treatments. Maximal safe surgical resection is the more effective therapy, alone or combined with adjuvant therapy (chemotherapy, radiotherapy). Anti-epileptic drugs are not indicated for epilepsy prophylaxis in patients without seizures but only after the first seizure due to high risk of recurrence. As they may generate adverse effects and interfere with oncological treatments, the choice is based on efficacy, tolerability and potential interactions. New anti-epileptic non-enzyme-inducing drugs are recommended in first-line monotherapy in association with adjuvant oncological therapies. Enzyme-inhibiting drugs could have a favorable effect on survival. Late seizures are often related to tumor progression or recurrence. Discontinuation of anti-epileptic drugs could be considered after successful oncological treatment and a stable medical condition.

CONCLUSION

These guidelines are helpful for a rational therapy in tumoral epilepsy.

In vitro antineoplastic effects of brivaracetam and lacosamide on human glioma cells

Background

Epilepsy is a frequent symptom in patients with glioma. Although treatment with antiepileptic drugs is generally effective in controlling seizures, drug-resistant patients are not uncommon. Multidrug resistance proteins (MRPs) and P-gp are over-represented in brain tissue of patients with drug-resistant epilepsy, suggesting their involvement in the clearance of antiepileptic medications. In addition to their anticonvulsant action, some drugs have been documented for cytotoxic effects. Aim of this study was to evaluate possible in vitro cytotoxic effects of two new-generation antiepileptic drugs on a human glioma cell line U87MG.

Methods

Cytotoxicity of brivaracetam and lacosamide was tested on U87MG, SW1783 and T98G by MTS assay. Expression of chemoresistance molecules was evaluated using flow cytometry in U87MG and human umbilical vein endothelial cells (HUVECs). To investigate the putative anti-proliferative effect, apoptosis assay, microRNA expression profile and study of cell cycle were performed.

Results

Brivaracetam and lacosamide showed a dose-dependent cytotoxic and anti-migratory effects. Cytotoxicity was not related to apoptosis. The exposure of glioma cells to brivaracetam and lacosamide resulted in the modulation of several microRNAs; particularly, the effect of miR-195-5p modulation seemed to affect cell cycle, while miR-107 seemed to be implicated in the inhibition of cells migration. Moreover, brivaracetam and lacosamide treatment did not modulate the expression of chemoresistance-related molecules MRPs1-3-5, GSTπ, P-gp on U87MG and HUVECs.

Conclusion

Based on antineoplastic effect of brivaracetam and lacosamide on glioma cells, we assume that patients with glioma could benefit by the treatment with these two molecules, in addition to standard therapeutic options.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-017-0546-9) contains supplementary material, which is available to authorized users.

The Effect of Sodium Valproate on the Glioblastoma U87 Cell Line Tumor Development on the Chicken Embryo Chorioallantoic Membrane and on EZH2 and p53 Expression

Literature data support evidences that glioblastoma (GBM) patients experience prolonged survival due to sodium valproate (NaVP) treatment. The study assessed the human GBM cell U87 xenograft studied in the chicken embryo chorioallantoic membrane (CAM) model evaluating NaVP effect on tumor. Three groups of tumors (each n = 10) were studied: nontreated, treated with 4 mM, and treated with 8 mM of NaVP. The majority of tumors without NaVP treatment during tumor growth destroyed the chorionic epithelium, invaded the mesenchyme, and induced angiogenesis. Incidence of tumor formation on CAM without invasion into the mesenchyme was higher when U87 cells were treated with NaVP; the effect significantly increased with NaVP concentration. Treatment with 8 mM of NaVP did not show clear dynamics of tumor growth during 5 days; at the same time, the angiogenesis failed. With a strong staining of EZH2, p53 in tumors without NaVP treatment was found, and NaVP significantly decreased the expression of EZH2- and p53-positive cells; the effect was significantly higher at its 8 mM concentration. NaVP has a function in blocking the growth, invasion, and angiogenesis of tumor in the CAM model; tumor growth interferes with EZH2 and p53 molecular pathways, supporting the NaVP potential in GBM therapy.

A practical guide to the use of anti-epileptic drugs by neurosurgeons

Initiation of anti-epileptic drugs is increasingly relevant to daily neurosurgical practice. Intracranial pathologies ranging from brain tumours to subarachnoid haemorrhage and traumatic brain injury are commonly associated with the subsequent development of seizures. The scope and range of anti-epileptic drugs available has increased dramatically in recent years and understanding the evidence base behind this class of drugs in addition to their interaction/side effect profiles is essential. In this review we aim to generate a practical guide for neurosurgeons regarding the use of different anti-epileptic medications in common neurosurgical conditions, including considerations for their use in pregnancy.

Pattern of care and outcome in elderly patients with glioblastoma: Data in 151 patients from 3 Lombardia Hospitals

The appropriate treatment approach for elderly patients with glioblastoma multiforme (GBM) is unclear, although different studies suggest survival benefit in fit patients treated with radiotherapy and chemiotherapy after surgery. We performed a retrospective analysis of 151 patients older than 65years with GBM treated in 3 Lombardia Hospitals. In univariate regression analysis higher KPS (p=0.02), macroscopical total resection (p<0.003), radiotherapy (p<0.0001), chemotherapy (p<0.0001) and second line chemotheraphy (p=0.02) were of positive prognostic value. On the contrary older age (>70years), presence of seizure at onset and additional resection after tumor recurrence did not influence OS. Multivariate analysis revealed radiotherapy (HR 0.2 p<0.0001) and extent of surgery (HR 0.3, p=0,0063) as positive independent prognostic factors. Patients receiving radio-chemiotherapy displayed more treatment-related toxicities with a slightly prolonged OS versus those receiving hypofractionated radiotherapy. With the limits of a retrospective study, our data suggest that in elderly fit patients extensive surgery should be considered, moreover adjuvant treatments led to an increase in OS. Randomized controlled study are needed to develop treatment guidelines for elderly GBM patients and to assess whether the combination of post-surgical radio and chemiotherapy may be superior to hypofractionated radiotherapy and chemiotherapy in fit patients.

Therapeutic Targeting of Histone Modifications in Adult and Pediatric High-Grade Glioma

Recent exciting work partly through The Cancer Genome Atlas has implicated epigenetic mechanisms including histone modifications in the development of both pediatric and adult high-grade glioma (HGG). Histone lysine methylation has emerged as an important player in regulating gene expression and chromatin function. Lysine (K) 27 (K27) is a critical residue in all seven histone 3 variants and the subject of posttranslational histone modifications, as it can be both methylated and acetylated. In pediatric HGG, two critical single-point mutations occur in the H3F3A gene encoding the regulatory histone variant H3.3. These mutations occur at lysine (K) 27 (K27M) and glycine (G) 34 (G34R/V), both of which are involved with key regulatory posttranscriptional modifications. Therefore, these mutations effect gene expression, cell differentiation, and telomere maintenance. In recent years, alterations in histone acetylation have provided novel opportunities to explore new pharmacological targeting, with histone deacetylase (HDAC) overexpression reported in high-grade, late-stage proliferative tumors. HDAC inhibitors have shown promising therapeutic potential in many malignancies. This review focuses on the epigenetic mechanisms propagating pediatric and adult HGGs, as well as summarizing the current advances in clinical trials using HDAC inhibitors.

Epigenetic modification in chromatin machinery and its deregulation in pediatric brain tumors: Insight into epigenetic therapies

Malignancies are characterized by the reprogramming of epigenetic patterns. This reprogramming includes gains or losses in DNA methylation and disruption of normal patterns of covalent histone modifications, which are associated with changes in chromatin remodeling processes. This review will focus on the mechanisms underlying this reprogramming and, specifically, on the role of histone modification in chromatin machinery and the modifications in epigenetic processes occurring in brain cancer, with a specific focus on epigenetic therapies for pediatric brain tumors.

Management of neuro-oncologic emergencies

Patients with brain tumors and systemic malignancies are subject to diverse neurologic complications that require urgent evaluation and treatment. These neurologic conditions are commonly due to the tumor's direct effects on the nervous system, such as cerebral edema, increased intracranial pressure, seizures, spinal cord compression, and leptomeningeal metastases. In addition, neurologic complications can develop as a result of thrombocytopenia, coagulopathy, hyperviscosity syndromes, infection, immune-related disorders, and adverse effects of treatment. Patients may present with typical disease syndromes. However, it is not uncommon for patients to have more subtle, nonlocalizing manifestations, such as alteration of mental status, that could be attributed to other systemic, nonneurologic complications. Furthermore, neurologic complications are at times the initial manifestations of an undiagnosed malignancy. Therefore a high index of suspicion is essential for rapid assessment and management. Timely intervention may prolong survival and improve quality of life. In this chapter, we will discuss the common neuro-oncologic emergencies, including epidemiology, pathophysiology, clinical presentation, diagnosis, and treatment.

Epileptic features and survival in glioblastomas presenting with seizures

INTRODUCTION

The prognostic value of seizures in patients with glioblastoma is currently under discussion. The objective of this research was to study the risk factors associated with seizures occurring at the diagnosis of glioblastoma and the role of seizures as a predictive factor for survival.

MATERIAL AND METHODS

We prospectively analyzed the clinical data over the course of the disease, baseline MR imaging, and histological characteristics (p53 overexpression, the Ki67 proliferation index, and presence of the IDH1 R132H mutation), in glioblastomas treated in a single hospital from November 2012 to July 2014. The study follow-up cutoff point was October 2015.

RESULTS

In total, 56 patients were recruited (57% men, mean age 57 years). Median baseline score on the Karnofsky performance scale was 80. Complete tumor debulking followed by radiochemotherapy was achieved in 58.9%. Mean survival was 13.6 months. Epileptic seizures were the presenting symptom in 26.6% of patients, and 44.6% experienced seizures at some point during the course of the disease. On multivariate analysis, the single factor predicting shorter survival was age older than 60 years (hazard ratio 3.565 (95%CI, 1.491-8.522), p=0.004). Seizures were associated with longer survival only in patients younger than 60 years (p=0.035). Younger age, the IDH1 R132H mutation, and p53 overexpression (>40%) were related to seizures at presentation. Baseline MRI findings, including tumor size, and the Ki67 proliferation index were not associated with the risk of epileptic seizures or with survival. Prophylactic antiepileptic drugs did not increase survival time.

CONCLUSIONS

Seizures as the presenting symptom of glioblastoma predicted longer survival in adults younger than 60 years. The IDH1 R132H mutation and p53 overexpression (>40%) were associated with seizures at presentation. Seizures showed no relationship with the tumor size or proliferation parameters.

Regression of a glioblastoma multiforme: spontaneous versus a potential antineoplastic effect of dexamethasone and levetiracetam

Patients with grade IV astrocytoma or glioblastoma multiforme (GBM) have a median survival of <12 months, increased to 14.6 months by maximal safe resection with radiation and temozolamide. In the absence of chemotherapy, radiotherapy or chemoradiotherapy, spontaneous regression of GBM or regression while only being on dexamethasone (DEX) and levetiracetam (LEV) have seldom been reported. Here, we present a case of a patient who had significant regression of the GBM with DEX and LEV alone. In this study, we hypothesise a plausible antineoplastic role of DEX and or LEV in GBM and highlight molecular, preclinical and clinical studies supporting this role.

NEOPLASM study: Real-life use of lacosamide in patients with brain tumor-related epilepsy

BACKGROUND

The choice of antiepileptic drug (AED) therapy in patients with brain tumor-related epilepsy (BTRE) is complicated, and there are a lack of robust clinical trial data to date.

METHODS

The NEOPLASM (Neuroncologic Patients treated with LAcoSaMide) study was a 6-month, multicenter, retrospective, observational study in patients with BTRE treated with lacosamide. Patients were started on lacosamide because of a lack of efficacy or adverse events (AEs) with prior AEDs or suitability versus other AEDs, according to clinical practice. The primary efficacy variable was the seizure-free rate at 6months. Safety variables included the proportion of patients with an AE and the proportion with an AE that led to discontinuation.

RESULTS

Overall, 105 patients from 14 hospital centers were included in the analysis. Treatment with lacosamide for 6months resulted in a 30.8% seizure-free rate, and 66.3% of patients had a ≥50% seizure reduction (responders). In the subset of patients included because of a lack of efficacy with prior AEDs, seizure-free rates were 28.0%, and 66.7% of patients were responders. No statistically significant differences in efficacy were observed according to the mechanism of action or enzyme-inducing properties of concomitant AEDs. Adverse events were reported by 41.9% of patients at 6months, and 4.7% of them led to discontinuation. The most common AEs were somnolence/fatigue and dizziness. Notably, 57.1% of the patients who were switched to lacosamide because of AEs with their previous therapy did not report any AE at 6-month follow-up.

CONCLUSIONS

In this open-label, observational study, lacosamide appeared to be effective and well tolerated in a large population of patients with BTRE. Lacosamide may therefore be a promising option for the treatment of patients with BTRE.

Valproic acid reduces hair loss and improves survival in patients receiving temozolomide-based radiation therapy for high-grade glioma

PURPOSE

Valproic acid (VPA), a histone deacetylase (HDAC) inhibitor, is also used to manage seizures in glioblastoma patients. HDAC inhibitors can protect normal cells and tissues from the deleterious effects of radiotherapy, and VPA is reported to improve the survival of glioblastoma patients receiving chemoradiation therapy. VPA also promotes hair growth, and thus has the potential to reduce the radiotherapy side effect of hair loss while improving the survival of patients with glioblastoma. The purpose of this study was to determine whether VPA use during radiotherapy for high-grade glioma is associated with decreased side effects of radiotherapy and an improvement in overall survival (OS) and progression-free survival (PFS).

METHODS

Medical records of 112 patients with high-grade glioma were retrospectively reviewed. We grouped patients by VPA use or non-use during radiotherapy, and evaluated hair loss, OS, and PFS.

RESULTS

The radiation dose and fractionation at the onset of hair loss were 4 Gy and two fractions higher, respectively, in the VPA group compared with the VPA non-use group (P < 0.01). Median OS was 42.2 and 20.3 months in the VPA use and non-use groups, respectively (P < 0.01; hazard ratio [HR], 0.36; 95% confidence interval [CI], 0.18-0.74). Median PFS was 22.7 and 11.0 months in the VPA use and non-use groups, respectively (P = 0.099; HR, 0.62; 95% CI, 0.36-1.09).

CONCLUSIONS

VPA use during radiotherapy for glioma is associated with delayed hair loss and improvement in survival. Hair loss prevention benefits patients suffering from the deleterious effects of radiation.

Valproic acid enhances the efficacy of radiation therapy by protecting normal hippocampal neurons and sensitizing malignant glioblastoma cells

Neurocognitive deficits are serious sequelae that follow cranial irradiation used to treat patients with medulloblastoma and other brain neoplasms. Cranial irradiation causes apoptosis in the subgranular zone of the hippocampus leading to cognitive deficits. Valproic acid (VPA) treatment protected hippocampal neurons from radiation-induced damage in both cell culture and animal models. Radioprotection was observed in VPA-treated neuronal cells compared to cells treated with radiation alone. This protection is specific to normal neuronal cells and did not extend to cancer cells. In fact, VPA acted as a radiosensitizer in brain cancer cells. VPA treatment induced cell cycle arrest in cancer cells but not in normal neuronal cells. The level of anti-apoptotic protein Bcl-2 was increased and the pro-apoptotic protein Bax was reduced in VPA treated normal cells. VPA inhibited the activities of histone deacetylase (HDAC) and glycogen synthase kinase-3β (GSK3β), the latter of which is only inhibited in normal cells. The combination of VPA and radiation was most effective in inhibiting tumor growth in heterotopic brain tumor models. An intracranial orthotopic glioma tumor model was used to evaluate tumor growth by using dynamic contrast-enhanced magnetic resonance (DCE MRI) and mouse survival following treatment with VPA and radiation. VPA, in combination with radiation, significantly delayed tumor growth and improved mouse survival. Overall, VPA protects normal hippocampal neurons and not cancer cells from radiation-induced cytotoxicity both in vitro and in vivo. VPA treatment has the potential for attenuating neurocognitive deficits associated with cranial irradiation while enhancing the efficiency of glioma radiotherapy.

The withdrawal of antiepileptic drugs in patients with low-grade and anaplastic glioma

INTRODUCTION

The withdrawal of antiepileptic drugs (AEDs) in World Health Organization (WHO) grade II-III glioma patients with epilepsy is controversial, as the presence of a symptomatic lesion is often related to an increased risk of seizure relapse. However, some glioma patients may achieve long-term seizure freedom after antitumor treatment, raising questions about the necessity to continue AEDs, particularly when patients experience serious drug side effects. Areas covered: In this review, we show the evidence in the literature from 1990-2016 for AED withdrawal in glioma patients. We put this issue into the context of risk factors for developing seizures in glioma, adverse effects of AEDs, seizure outcome after antitumor treatment, and outcome after AED withdrawal in patients with non-brain tumor related epilepsy. Expert commentary: There is currently scarce evidence of the feasibility of AED withdrawal in glioma patients. AED withdrawal could be considered in patients with grade II-III glioma with a favorable prognosis, who have achieved stable disease and long-term seizure freedom. The potential benefits of AED withdrawal need to be carefully weighed against the presumed risk of seizure recurrence in a shared decision-making process by both the clinical physician and the patient.

Anticonvulsant therapy in brain-tumor related epilepsy

Background. The lifetime risk of patients with brain tumors to have focal epileptic seizures is 10-100%; the risk depends on different histology. Specific guidelines for drug treatment of brain tumor-related seizures have not yet been established.

Aim. This review addresses the special aspects of antiepileptic drug (AED) therapy in brain tumor-related epilepsy.

Methods. We analyzed the literature up to December 2015.

Results. Based on current evidence the management of tumor-related seizures does not differ substantially from that applied to epilepsies from other etiologies. Therefore, the choice of an AED is based, above all, on tolerability and pharmacokinetic interactions with chemotherapeutic drugs. Levetiracetam is recommended by many authors as first-line therapy in brain tumor-related epilepsy. Due to the possibility of interactions, the combination of enzyme-inducing AEDs and chemotherapeutic drugs, is usually not recommended as a first choice. Currently there is no evidence that prophylactic prescription of long-term AEDs in brain tumor-patients who did not present with seizures is justified. Because of the high risk of recurrence, however, AED treatment should be strongly considered after a single brain tumor-related seizure. The decision to withdraw AEDs must carefully consider the risk of seizure recurrence.

Conclusion. At present levetiracetam is the preferred drug in brain tumor-related epilepsy, especially when drug interactions need to be avoided. In the future we hope to acquire more targeted drugs against this disorder by uncovering its pathogenesis.

Investigational new drugs for brain cancer

INTRODUCTION

Despite substantial improvements in standards of care, the most common aggressive pediatric and adult high-grade gliomas (HGG) carry uniformly fatal diagnoses due to unique treatment limitations, high recurrence rates and the absence of effective treatments following recurrence. Recent advancements in our understanding of the pathophysiology, genetics and epigenetics as well as mechanisms of immune surveillance during gliomagenesis have created new knowledge to design more effective and target-directed therapies to improve patient outcomes.

AREAS COVERED

In this review, the authors discuss the critical genetic, epigenetic and immunologic aberrations found in gliomas that appear rational and promising for therapeutic developments in the presence and future. The current state of the latest therapeutic developments including tumor-specific targeted drug therapies, metabolic targeting, epigenetic modulation and immunotherapy are summarized and suggestions for future directions are offered. Furthermore, they highlight contemporary issues related to the clinical development, such as challenges in clinical trials and toxicities.

EXPERT OPINION

The commitment to understanding the process of gliomagenesis has created a catalogue of aberrations that depict multiple mechanisms underlying this disease, many of which are suitable to therapeutic inhibition and are currently tested in clinical trials. Thus, future treatment endeavors will employ multiple treatment modalities that target disparate tumor characteristics personalized to the patient's individual tumor.

The endoplasmic reticulum stress/unfolded protein response in gliomagenesis, tumor progression and as a therapeutic target in glioblastoma

Endoplasmic reticulum (ER) stress disrupts among others protein homeostasis in cells leading to the activation of the unfolded protein response (UPR) that is crucial for restoring this balance and cell survival. Hypoxia, reactive oxygen species and nutrient deprivation, conditions commonly present in the tumor microenvironment, are well-known triggers of the UPR. Apart from being an adaptive response, recently the UPR has been implicated in oncogenesis. Here we review the current understanding of the UPR in the most life threatening brain tumor in adults, glioblastoma multiforme (GBM). The UPR is controlled by BiP/GRP78 and three different sensors, PERK, IRE1 and ATF6. In orthotopic GBM mouse models IRE1 was reported to control angiogenesis, invasion and mesenchymal differentiation. Furthermore, PERK also was found to stimulate GBM growth. However, a direct role of the UPR in gliomagenesis remains to be demonstrated. Patient samples display chronic activation of the UPR and in vitro standard chemo- and radiotherapy partially act by aggravating ER stress leading to cell death. The UPR has been linked to enhanced sensitivity for apoptosis-inducing agents such as TRAIL and MDA-7. A number of agents such as proteasome inhibitors and several natural products were reported to exert cytotoxicity by enhancing ER stress in GBM cells, and some demonstrated activity in clinical studies. Finally, ER stress was suggested to be implicated in the maintenance of homeostasis in GBM stem cells. Taken together, the UPR appears to play an important role in GBM tumor progression and is a promising target for developing novel therapeutic interventions.

SEL1L SNP rs12435998, a predictor of glioblastoma survival and response to radio-chemotherapy

The suppressor of Lin-12-like (C. elegans) (SEL1L) is involved in the endoplasmic reticulum (ER)-associated degradation pathway, malignant transformation and stem cells.

In 412 formalin-fixed and paraffin-embedded brain tumors and 39 Glioblastoma multiforme (GBM) cell lines, we determined the frequency of five SEL1L single nucleotide genetic variants with regulatory and coding functions by a SNaPShot™ assay. We tested their possible association with brain tumor risk, prognosis and therapy.

We studied the in vitro cytotoxicity of valproic acid (VPA), temozolomide (TMZ), doxorubicin (DOX) and paclitaxel (PTX), alone or in combination, on 11 GBM cell lines, with respect to the SNP rs12435998 genotype.

The SNP rs12435998 was prevalent in anaplastic and malignant gliomas, and in meningiomas of all histologic grades, but unrelated to brain tumor risks. In GBM patients, the SNP rs12435998 was associated with prolonged overall survival (OS) and better response to TMZ-based radio-chemotherapy. GBM stem cells with this SNP showed lower levels of SEL1L expression and enhanced sensitivity to VPA.