Antiepileptic drugs in patients with malignant brain tumor: beyond seizures and pharmacokinetics

Glioblastoma disrupts cortical network activity at multiple spatial and temporal scales

The emergence of glioblastoma in cortical tissue initiates early and persistent neural hyperexcitability with signs ranging from mild cognitive impairment to convulsive seizures. The influence of peritumoral synaptic density, expansion dynamics, and spatial contours of excess glutamate upon higher order neuronal network modularity is unknown. We combined cellular and widefield imaging of calcium and glutamate fluorescent reporters in two glioblastoma mouse models with distinct synaptic microenvironments and infiltration profiles. Functional metrics of neural ensembles are dysregulated during tumor invasion depending on the stage of malignant progression and tumor cell proximity. Neural activity is differentially modulated during periods of accelerated and inhibited tumor expansion. Abnormal glutamate accumulation precedes and outpaces the spatial extent of baseline neuronal calcium signaling, indicating these processes are uncoupled in tumor cortex. Distinctive excitability homeostasis patterns and functional connectivity of local and remote neuronal populations support the promise of precision genetic diagnosis and management of this devastating brain disease.

Novel therapeutic strategies in glioma targeting glutamatergic neurotransmission

High grade gliomas carry a poor prognosis despite aggressive surgical and adjuvant approaches including chemoradiotherapy. Recent studies have demonstrated a mitogenic association between neuronal electrical activity and glioma growth involving the PI3K-mTOR pathway. As the predominant excitatory neurotransmitter of the brain, glutamate signalling in particular has been shown to promote glioma invasion and growth. The concept of the neurogliomal synapse has been established whereby glutamatergic receptors on glioma cells have been shown to promote tumour propagation. Targeting glutamatergic signalling is therefore a potential treatment option in glioma. Antiepileptic medications decrease excess neuronal electrical activity and some may possess anti-glutamate effects. Although antiepileptic medications continue to be investigated for an anti-glioma effect, good quality randomised trial evidence is lacking. Other pharmacological strategies that downregulate glutamatergic signalling include riluzole, memantine and anaesthetic agents. Neuromodulatory interventions possessing potential anti-glutamate activity include deep brain stimulation and vagus nerve stimulation - this contributes to the anti-seizure efficacy of the latter and the possible neuroprotective effect of the former. A possible role of neuromodulation as a novel anti-glioma modality has previously been proposed and that hypothesis is extended to include these modalities. Similarly, the significant survival benefit in glioblastoma attributable to alternating electrical fields (Tumour Treating Fields) may be a result of disruption to neurogliomal signalling. Further studies exploring excitatory neurotransmission and glutamatergic signalling and their role in glioma origin, growth and propagation are therefore warranted.

The evidence for repurposing anti-epileptic drugs to target cancer

Antiepileptic drugs are versatile drugs with the potential to be used in functional drug formulations with drug repurposing approaches. In the present review, we investigated the anticancer properties of antiepileptic drugs and interlinked cancer and epileptic pathways. Our focus was primarily on those drugs that have entered clinical trials with positive results and those that provided good results in preclinical studies. Many contributing factors make cancer therapy fail, like drug resistance, tumor heterogeneity, and cost; exploring all alternatives for efficient treatment is important. It is crucial to find new drug targets to find out new antitumor molecules from the already clinically validated and approved drugs utilizing drug repurposing methods. The advancements in genomics, proteomics, and other computational approaches speed up drug repurposing. This review summarizes the potential of antiepileptic drugs in different cancers and tumor progression in the brain. Valproic acid, oxcarbazepine, lacosamide, lamotrigine, and levetiracetam are the drugs that showed potential beneficial outcomes against different cancers. Antiepileptic drugs might be a good option for adjuvant cancer therapy, but there is a need to investigate further their efficacy in cancer therapy clinical trials.

The Antiepileptic Drug Oxcarbazepine Inhibits the Growth of Patient-Derived Isocitrate Dehydrogenase Mutant Glioma Stem-like Cells

Patients diagnosed with isocitrate dehydrogenase mutant (IDH^mut) gliomas suffer frequently from seizures. Although the clinical course is less aggressive than that of its IDH wildtype counterpart, recent discoveries have shown that epileptic activity can promote tumor proliferation. However, it is not known if antiepileptic drugs confer additional value by inhibiting tumor growth. In this study, the antineoplastic properties of 20 FDA-approved antiepileptic drugs (AEDs) were tested in six patient-derived IDH^mut glioma stem-like cells (GSCs). Cell proliferation was assessed using the CellTiterGlo-3D assay. Two of the screened drugs (oxcarbazepine and perampanel) demonstrated an antiproliferative effect. A subsequent eight-point dose-response curve proved the dose-dependent growth inhibition for both drugs, but only oxcarbazepine reached an IC₅₀ value below 100 µM in 5/6 GSCs (mean 44.7 µM; range 17.4-98.0 µM), approximating the possible c_max for oxcarbazepine in patient serums. Furthermore, the treated GSC spheroids were 82% smaller (mean volume 1.6 nL vs. 8.7 nL; p = 0.01 (live/dead^TM fluorescence staining)), and the apoptotic events increased by more than 50% (caspase-3/7 activity; p = 0.006). Taken together, this drug screen of a large series of antiepileptic drugs identified oxcarbazepine as a potent proapoptotic drug in IDH^mut GSCs, which combines antiepileptic and antineoplastic properties to treat this seizure-prone patient population.

Anti-seizure medication is not associated with an increased risk to develop cancer in epilepsy patients

Objective

Whether anti-seizure medication (ASM) increases the risk for cancer has been debated for decades. While for some ASM, a carcinoma-promoting effect has been suspected, carcinoma-protective effects have been shown for other ASM. However, the issue remains unresolved as data from preclinical and clinical studies have been inconsistent and contradictory.

Methods

We collected anonymous patient data from practice neurologists throughout Germany between 2009 and 2018 using the IMS Disease Analyzer database (QuintilesIMS, Frankfurt, Germany). People with epilepsy (PWE) with an initial cancer diagnosis and antiepileptic therapy prior to the index date were 1:1 matched with a control group of PWE without cancer according to age, gender, index year, Charlson Comorbidity Index, and treating physician. For both groups, the risk to develop cancer under treatment with different ASMs was analyzed using three different models (ever use vs. never use (I), effect per one (II) and per five therapy years (III).

Results

A total of 3152 PWE were included (each group, n = 1,576; age = 67.3 ± 14.0 years). The risk to develop cancer was not significantly elevated for any ASM. Carbamazepine was associated with a decreased cancer risk (OR Model I: 0.699, p < .0001, OR Model II: 0.952, p = .4878, OR Model III: 0.758, p < .0004).

Significance

Our findings suggest that ASM use does not increase the risk of cancer in epilepsy patients.

Supplementary Information

The online version of this article (10.1007/s00415-020-10379-4) contains supplementary material, which is available to authorized users.

The Korean Society for Neuro-Oncology (KSNO) Guideline for Antiepileptic Drug Usage of Brain Tumor: Version 2021.1

Background

To date, there has been no practical guidelines for the prescription of antiepileptic drugs (AEDs) in brain tumor patients in Korea. Thus, the Korean Society for Neuro-Oncology (KSNO), a multidisciplinary academic society, had begun preparing guidelines for AED usage in brain tumors since 2019.

Methods

The Working Group was composed of 27 multidisciplinary medical experts in Korea. References were identified through searches of PubMed, MEDLINE, EMBASE, and Cochrane CENTRAL using specific and sensitive keywords as well as combinations of the keywords.

Results

The core contents are as follows. Prophylactic AED administration is not recommended in newly diagnosed brain tumor patients without previous seizure history. When AEDs are administered during peri/postoperative period, it may be tapered off according to the following recommendations. In seizure-naïve patients with no postoperative seizure, it is recommended to stop or reduce AED 1 week after surgery. In seizure-naïve patients with one early postoperative seizure (<1 week after surgery), it is advisable to maintain AED for at least 3 months before tapering. In seizure-naïve patients with ≥2 postoperative seizures or in patients with preoperative seizure history, it is recommended to maintain AEDs for more than 1 year. The possibility of drug interactions should be considered when selecting AEDs in brain tumor patients. Driving can be allowed in brain tumor patients when proven to be seizure-free for more than 1 year.

Conclusion

The KSNO suggests prescribing AEDs in patients with brain tumor based on the current guideline. This guideline will contribute to spreading evidence-based prescription of AEDs in brain tumor patients in Korea.

Epileptogenesis and oncogenesis: An antineoplastic role for antiepileptic drugs in brain tumours?

The first description of epileptic seizures due to brain tumours occurred in 19th century. Nevertheless, after over one hundred years, scientific literature is still lacking on how epilepsy and its treatment can affect tumour burden, progression and clinical outcomes. In patients with brain tumours, epilepsy dramatically impacts their quality of life (QoL). Even antiepileptic therapy seems to affect tumor lesion development. Numerous studies suggest that certain actors involved in epileptogenesis (inflammatory changes, glutamate and its ionotropic and metabotropic receptors, GABA-A and its GABA-AR receptor, as well as certain ligand- and voltage-gated ion channel) may also contribute to tumorigenesis. Although some antiepileptic drugs (AEDs) are known operating on such mechanisms underlying epilepsy and tumor development, few preclinical and clinical studies have tried to investigate them as targets of pharmacological tools acting to control both phenomena. The primary aim of this review is to summarize known determinants and pathophysiological mechanisms of seizures, as well as of cell growth and spread, in patients with brain tumors. Therefore, a special focus will be provided on the anticancer effects of commonly prescribed AEDs (including levetiracetam, valproic acid, oxcarbazepine and others), with an overview of both preclinical and clinical data. Potential clinical applications of this finding are discussed.

Paternal Exposure to Carbamazepine Impacts Zebrafish Offspring Reproduction Over Multiple Generations

Chronic low-concentration chemical exposures may have both direct health outcomes on adults and indirect effects on their offspring. Using zebrafish, we examined the impacts of chronic, low-concentration carbamazepine (CBZ) exposure on a suite of male reproductive endpoints in the parents and four generations of offspring reared in clean water. CBZ is one of the most frequently detected pharmaceutical residues in water, is a histone deacetylase inhibitor in mammals, and is reported to lower androgens in mammals and fish. Exposure of adult zebrafish to 10 μg/L CBZ for 6 weeks decreased reproductive output, courtship and aggressive behaviors, 11-ketotestosterone (11KT), and sperm morphology but did not impact milt volume or sperm swimming speed. Pairwise breeding generated lineages of offspring with both parents exposed and two lineages where only one parent was exposed; the control lineage had unexposed parents. Reproductive output and male reproductive indices were assessed in F₁-F₄ offspring to determine whether parental CBZ exposure had transgenerational impacts. The offspring of CBZ-exposed males had lower 11KT, reproductive output, altered courtship, aggression, and sperm morphology compared to the lineage from unexposed parents. Our results indicate that parental carbamazepine exposure history impacts the unexposed progeny up to the F₄ generations and that paternal, but not maternal, exposure is most important for the reproductive health of male offspring.

AMPA receptor antagonist perampanel affects glioblastoma cell growth and glutamate release in vitro

Epileptic seizures are frequent in patients with glioblastoma, and anticonvulsive treatment is often necessary. While clinical guidelines recommend all approved anticonvulsants, so far it is still unclear which of the available drugs is the best therapeutic option for treating glioma-associated seizures, also in view of possible anti-tumorigenic effects. In our study, we employed four patient-derived low-passage cell lines of glioblastoma and three cell lines of brain metastases, and challenged these cultures with four anticonvulsants with different mechanisms of action: levetiracetam, valproic acid, carbamazepine and perampanel. Cell proliferation was determined by bromodeoxyuridine incorporation. To further analyze the effects of perampanel, apoptosis induction was measured by caspase 3/7 activation. Glutamate release was quantified and glucose uptake was determined using 18F-fluorodeoxyglucose. Real-time polymerase chain reaction was employed to assess the expression of genes associated with glutamate release and uptake in brain tumor cells. Of the four anticonvulsants, only perampanel showed systematic inhibitory effects on cell proliferation, whereas all other anticonvulsants failed to inhibit glioma and metastasis cell growth in vitro. Metastasis cells were much more resistant to perampanel than glioblastoma cell lines. Glucose uptake was attenuated in all glioblastoma cells after perampanel exposure, whereas cell death via apoptosis was not induced. Extracellular glutamate levels were found to be significantly higher in glioblastoma cell lines as compared to metastasis cell lines, but could be reduced by perampanel exposure. Incubation with perampanel up-regulated glutamine synthetase expression in glioblastoma cells, whereas treatment with valproic acid and levetiracetam downregulated excitatory amino acid transporter-2 expression. Overall, our data suggest that perampanel acts as an anticonvulsive drug and additionally mediated anti-tumorigenic effects.

Lacosamide at therapeutic concentrations induces histone hyperacetylation in vitro

Inhibition of histone deacetylases (HDACs) and subsequent hyperacetylation of histone proteins lead to altered gene expression associated with therapeutic drug effects, but also with teratogenicity. The only US Food and Drug Administration (FDA)-approved antiepileptic drug that has been consistently shown to induce histone hyperacetylation is valproic acid. More recently, lacosamide was reported to interfere with histone modifications, but histone hyperacetylation was not demonstrated. In the current study we evaluated the effects of lacosamide on histone acetylation in vitro. MDA-MB-231 (triple-negative breast cancer) cells and human placental BeWo cells were exposed for 16 hours to 5-20 μg/ml (20-80 μm) lacosamide. Histone acetylation was evaluated by western blot analysis. We additionally measured HDAC1 activity in the presence of lacosamide. At 5, 10, and 20 μg/ml, lacosamide enhanced histone acetylation in BeWo cells by 1.7-fold (p > 0.05), 3.4-fold (p < 0.05), and 3.0-fold (p > 0.05), respectively. Histone H3 acetylation and total histones H3 and H4 levels were not significantly modified (p > 0.05). The magnitude of change in histone acetylation in MDA-MB-231 cells was smaller (p > 0.05). In contrast to valproic acid, lacosamide did not inhibit HDAC1. Our findings suggest that the effects of lacosamide on gene expression, and the related potential antitumor activity and teratogenicity, may differ from those of valproic acid.

Long-term retention rates of antiepileptic drugs used in acute seizures

PURPOSE

A number of antiepileptic drugs (AEDs) are currently available for treating acute seizures. It is recommended to select the initial treatment option according to the type of epileptic syndrome and the patient's clinical characteristics, but little is known about the long-term retention rates of AEDs started in the emergency department.

METHODS

We recruited patients admitted with seizures over a two-year period. All patients underwent early neurological assessment, EEG testing, and neuroimaging. The treatments received at baseline and at one year of follow-up were compared.

RESULTS

In total, 225 patients were included. Overall, monotherapy with levetiracetam was the regimen most often used in patients with new-onset seizures, whereas other AEDs were mainly used in patients previously treated with other drugs. Lacosamide use was most likely associated with the presence of lesion related seizures in elderly patients, and carboxamides with focal onset seizures of unknown cause. The mean retention rate of the total of AED treatments was nearly 70%. The main cause leading to discontinuation was the development of intolerable adverse events. Levetiracetam use decreased as lacosamide use increased in the overall group of patients.

CONCLUSION

Our study shows that there is a trend to use newer AEDs, particularly levetiracetam, as the first option in new-onset seizures in the emergency room. However, levetiracetam use significantly decreased over follow-up, mainly because of the development of adverse events. The use of other, better-tolerated AEDs, such lacosamide predominated in elderly patients and patients with lesion related seizures, or carboxamides in epilepsies of unknown etiology.

Perampanel: Does it have broad-spectrum potential?

This article reviews the profile of perampanel, a novel noncompetitive α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate (AMPA) receptor antagonist, and its role as a potential broad-spectrum antiepileptic drug in the treatment of epilepsy. For this narrative review, data were collected using specified search criteria. Articles reporting the evidence for perampanel's efficacy from preclinical models, phase 3 clinical studies, observational studies, and descriptive evidence were included. AMPA receptors play a key role in mediating the action of glutamate at the excitatory synapse. Preclinical research showed the AMPA receptor blockade to constitute a promising target for antiepileptic drug therapy. In animal models, perampanel proved to be protective against seizures and reduce seizure severity and duration. Four phase-3 randomized controlled trials (3 in patients with focal seizures and one in primary generalized tonic-clonic seizures in idiopathic generalized epilepsy) have been completed. In focal (partial) onset seizures, perampanel (4, 8, and 12 mg) significantly reduced seizure frequency per 28 days (23.3%-28.8% vs 12.8%; P < .01) and responder rates (≥50% reduction in seizures) (28.5%-35.3% vs 19.3%; P < .05) compared with placebo. In primary generalized tonic-clonic seizures, perampanel 8 mg resulted in greater reduction in seizure frequency per 28 days (-76.5% vs -38.4%; P < .0001) and responder rate (64.2% vs 39.5%; P = .0019) than placebo. The efficacy, safety, and tolerability of perampanel have been reproduced in real-world clinical practice, and the agent has been shown to be effective in other epilepsy syndromes. Perampanel is a potentially broad-spectrum antiepileptic drug with a novel mechanism of action that may be a useful addition for patients with epilepsy with various seizure types. The availability of novel antiepileptic drugs for epilepsy treatment enables more individualized treatment for these patients.

Choice of antiepileptic drugs affects the outcome in cancer patients with seizures

BACKGROUND

Seizures in cancer patients may occur as a result of CNS primary or metastatic tumor, brain surgery, vascular disease, pharmacologic treatment (including chemotherapy), radiation therapy, or metabolic disorders. The aims of the study were to a) determine whether seizures in cancer patients have prognostic implications and b) study patient outcome based on the antiepileptic drug used.

METHOD

This is a prospective comparative study that included adult cancer patients with and without seizures from May 2010 to November 2016 seen by the neuro-oncology unit at a cancer referral center. Variables included age, gender, oncologic characteristics, seizure features, treatment, and outcome. Parametric and non-parametric tests were used to compare groups, and Kaplan-Meier curves with the log-rank test were used to analyze survival. Cox multivariate regression tests were used to describe survival and compare groups.

RESULTS

A total of 823 patients were included; 419 (51%) patients had at least one seizure and were compared with 404 (49%) who did not experience seizures. Of the seizure group, 53% had brain metastases, 36% did not have a brain tumor, and 11% had a primary brain tumor. No survival differences were noted among patients with brain metastases or primary tumor with or without seizures. In the seizure group, 249 (59%) required only one antiepileptic drug, whereas 134 (32%) required 2 or more. A better overall survival was identified for patients prescribed carbamazepine (p = 0.02), lamotrigine (p = 0.015), levetiracetam (p = 0.03), and valproic acid (p = 0.009).

CONCLUSIONS

Patients with primary or metastatic brain tumors have the same overall survival with or without seizures. However, patients with seizures not treated with antiepileptics exhibit worse overall survival.

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.

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.