IDH1/2 wildtype gliomas grade 2 and 3 with molecular glioblastoma-like profile have a distinct course of epilepsy compared to IDH1/2 wildtype glioblastomas

The course of tumor-related epilepsy in glioblastoma patients: A retrospective analysis

PURPOSE

Many patients with glioblastoma suffer from tumor-related seizures. However, there is limited data on the characteristics of tumor-related epilepsy achieving seizure freedom. The aim of this study was to characterize the course of epilepsy in patients with glioblastoma and the factors that influence it.

METHODS

We retrospectively analyzed the medical records of glioblastoma patients treated at the University Hospital Erlangen between 01/2006 and 01/2020.

RESULTS

In the final cohort of patients with glioblastoma (n = 520), 292 patients (56.2 %) suffered from tumor-related epilepsy (persons with epilepsy, PWE). Levetiracetam was the most commonly used first-line antiseizure medication (n = 245, 83.9 % of PWE). The onset of epilepsy was preoperative in 154/292 patients (52.7 %). 136 PWE (46.6 %) experienced only one single seizure while 27/292 PWE (9.2 %) developed drug-resistant epilepsy. Status epilepticus occurred in 48/292 patients (16.4 %). Early postoperative onset (within 30 days of surgery) of epilepsy and total gross resection (compared with debulking) were independently associated with a lower risk of further seizures. We did not detect dose-dependent pro- or antiseizure effects of radiochemotherapy.

CONCLUSION

Tumor-related epilepsy occurred in more than 50% of our cohort, but drug-resistant epilepsy developed in less than 10% of cases. Epilepsy usually started before tumor surgery.

The complex molecular epileptogenesis landscape of glioblastoma

The cortical microenvironment surrounding malignant glioblastoma is a source of depolarizing crosstalk favoring hyperexcitability, tumor expansion, and immune evasion. Neosynaptogenesis, excess glutamate, and altered intrinsic membrane currents contribute to excitability dyshomeostasis, yet only half of the cases develop seizures, suggesting that tumor and host genomics, along with location, rather than mass effect, play a critical role. We analyzed the spatial contours and expression of 358 clinically validated human epilepsy genes in the human glioblastoma transcriptome compared to non-tumor adult and developing cortex datasets. Nearly half, including dosage-sensitive genes whose expression levels are securely linked to monogenic epilepsy, are strikingly enriched and aberrantly regulated at the leading edge, supporting a complex epistatic basis for peritumoral epileptogenesis. Surround hyperexcitability induced by complex patterns of proepileptic gene expression may explain the limited efficacy of narrowly targeted antiseizure medicines and the persistence of epilepsy following tumor resection and clarify why not all brain tumors provoke seizures.

A Mendelian randomization study of the entire phenome to explore the causal links between epilepsy

OBJECTIVE

The causes and triggering factors of epilepsy are still unknown. The results of genome-wide association studies can be utilized for a phenome-wide association study using Mendelian randomization (MR) to identify potential risk factors for epilepsy.

METHODS

This study utilizes two-sample MR analysis to investigate whether 316 phenotypes, including lifestyle, environmental factors, blood biomarker, and more, are causally associated with the occurrence of epilepsy. The primary analysis employed the inverse variance weighted (IVW) model, while complementary MR analysis methods (MR Egger, Wald ratio) were also employed. Sensitivity analyses were also conducted to evaluate heterogeneity and pleiotropy.

RESULTS

There was no evidence of a statistically significant causal association between the examined phenotypes and epilepsy following Bonferroni correction (p < 1.58 × 10-4) or false discovery rate correction. The results of the MR analysis indicate that the frequency of tiredness or lethargy in the last 2 weeks (p = 0.042), blood uridine (p = 0.003), blood propionylcarnitine (p = 0.041), and free cholesterol (p = 0.044) are suggestive causal risks for epilepsy. Lifestyle choices, such as sleep duration and alcohol consumption, as well as biomarkers including steroid hormone levels, hippocampal volume, and amygdala volume were not identified as causal factors for developing epilepsy (p > 0.05).

CONCLUSIONS

Our study provides additional insights into the underlying causes of epilepsy, which will serve as evidence for the prevention and control of epilepsy. The associations observed in epidemiological studies may be partially attributed to shared biological factors or lifestyle confounders.

Anti-epileptic drug use during adjuvant chemo-radiotherapy is associated with poorer survival in patients with glioblastoma: A nationwide population-based cohort study

INTRODUCTION

There are emerging but inconsistent evidences about anti-epileptic drugs (AEDs) as radio- or chemo-sensitizers to improve survival in glioblastoma patients. We conducted a nationwide population-based study to evaluate the impact of concurrent AED during post-operative chemo-radiotherapy on outcome.

MATERIAL AND METHODS

A total of 1057 glioblastoma patients were identified by National Health Insurance Research Database and Cancer Registry in 2008-2015. Eligible criteria included those receiving surgery, adjuvant radiotherapy and temozolomide, and without other cancer diagnoses. Survival between patients taking concurrent AED for 14 days or more during chemo-radiotherapy (AED group) and those who did not (non-AED group) were compared, and subgroup analyses for those with valproic acid (VPA), levetiracetam (LEV), or phenytoin were performed. Multivariate analyses were used to adjust for confounding factors.

RESULTS

There were 642 patients in the AED group, whereas 415 in the non-AED group. The demographic data was balanced except trend of more patients in the AED group had previous drug history of AEDs (22.6% vs. 18%, P 0.078). Overall, the AED group had significantly increased risk of mortality (HR = 1.18, P 0.016) compared to the non-AED group. Besides, an adverse dose-dependent relationship on survival was also demonstrated in the AED group (HR = 1.118, P 0.0003). In subgroup analyses, the significant detrimental effect was demonstrated in VPA group (HR = 1.29,P 0.0002), but not in LEV (HR = 1.18, P 0.079) and phenytoin (HR = 0.98, P 0.862).

CONCLUSIONS

Improved survival was not observed in patients with concurrent AEDs during chemo-radiotherapy. Our real-world data did not support prophylactic use of AEDs for glioblastoma patients.

Characteristics and Prognosis of Tumor-Related Epilepsy During Tumor Evolution in Patients With IDH Wild-Type Glioblastoma

BACKGROUND AND OBJECTIVES

Tumor-related epilepsy is a well-known symptom of glioblastoma. However, the particular characteristics of epileptic seizures related to glioblastoma, isocitrate dehydrogenase (IDH)-wild-type is almost unexplored longitudinally during the whole course of the disease. We assessed tumor-related epilepsy and seizure control during tumor evolution and the prognostic significance of tumor-related epilepsy.

METHODS

We performed an observational, retrospective single-center study at one tertiary referral neuro-oncology surgical center (2000-2020). We included adult patients treated for a newly diagnosed supratentorial glioblastoma, IDH-wild-type with available preoperative and postoperative MRI and with available epileptic seizure status at diagnosis. To determine factors associated with tumor-related epilepsy or seizure control, univariate analyses were performed using the χ2 or Fisher exact tests for categorical variables and the unpaired t test or Mann-Whitney rank-sum test for continuous variables. Predictors associated with tumor-related epilepsy and seizure control in unadjusted analysis were entered into backward stepwise logistic regression models.

RESULTS

One thousand six patients were enrolled. The cumulative incidence of tumor-related epilepsy increased during tumor evolution (33.1% at diagnosis, 44.7% after oncologic treatment, 52.4% at progression, and 51.8% at the end-of-life phase) and is related to tumor features (cortex involvement, no necrosis, and small volume). Uncontrolled epileptic seizures increased during tumor evolution (20.1% at diagnosis, 32.0% after oncologic treatment, 46.7% at progression, and 41.1% at the end-of-life phase). Epileptic seizure control after oncologic treatment was related to seizure features (uncontrolled before oncologic treatment and focal-to-bilateral tonic-clonic seizures) and to the extent of resection. Epileptic seizure control at tumor progression was related to seizure features (presence at diagnosis and uncontrolled after oncologic treatment) and to the time to progression. Tumor-related epilepsy at diagnosis was a predictor of a longer overall survival (adjusted hazard ratio, 0.78; 95% CI 0.67-0.90; p < 0.001) independent of age, Karnofsky Performance Status score, tumor location and volume, extent of resection, standard combined chemoradiotherapy, levetiracetam use, and MGMT promoter methylation.

DISCUSSION

The progression of tumor-related epilepsy with the evolution of glioblastoma, IDH-wild-type and the effects of surgery on seizure control argue for proper antiseizure medication and maximal safe resection. Tumor-related epilepsy is an independent predictor of a longer survival.

Exploring molecular glioblastoma: Insights from advanced imaging for a nuanced understanding of the molecularly defined malignant biology

Background

Molecular glioblastoma (molGB) does not exhibit the histologic hallmarks of a grade 4 glioma but is nevertheless diagnosed as glioblastoma when harboring specific molecular markers. MolGB can easily be mistaken for similar-appearing lower-grade astrocytomas. Here, we investigated how advanced imaging could reflect the underlying tumor biology.

Methods

Clinical and imaging data were collected for 7 molGB grade 4, 9 astrocytomas grade 2, and 12 astrocytomas grade 3. Four neuroradiologists performed VASARI-scoring of conventional imaging, and their inter-reader agreement was assessed using Fleiss κ coefficient. To evaluate the potential of advanced imaging, 2-sample t test, 1-way ANOVA, Mann-Whitney U, and Kruskal-Wallis test were performed to test for significant differences between apparent diffusion coefficient (ADC) and relative cerebral blood volume (rCBV) that were extracted fully automatically from the whole tumor volume.

Results

While conventional VASARI imaging features did not allow for reliable differentiation between glioma entities, rCBV was significantly higher in molGB compared to astrocytomas for the 5th and 95th percentile, mean, and median values (P < .05). ADC values were significantly lower in molGB than in astrocytomas for mean, median, and the 95th percentile (P < .05). Although no molGB showed contrast enhancement initially, we observed enhancement in the short-term follow-up of 1 patient.

Discussion

Quantitative analysis of diffusion and perfusion parameters shows potential in reflecting the malignant tumor biology of molGB. It may increase awareness of molGB in a nonenhancing, "benign" appearing tumor. Our results support the emerging hypothesis that molGB might present glioblastoma captured at an early stage of gliomagenesis.

Epilepsy in gliomas: recent insights into risk factors and molecular pathways

PURPOSE OF REVIEW

The purpose of this review is to discuss the molecular pathways governing the development of seizures in glioma patients.

RECENT FINDINGS

The intrinsic epileptogenicity of the neuronal component of glioneuronal and neuronal tumors is the most relevant factor for seizure development. The two major molecular alterations behind epileptogenicity are the rat sarcoma virus (RAS)/mitogen-activated protein kinase / extracellular signal-regulated kinase (MAPK/ERK) and phosphatidylinositol-3-kinase / protein kinase B / mammalian target of rapamycin (P13K/AKT/mTOR) pathways. The BRAFv600E mutation has been shown in experimental models to contribute to epileptogenicity, and its inhibition is effective in controlling both seizures and tumor growth. Regarding circumscribed astrocytic gliomas, either BRAFv600E mutation or mTOR hyperactivation represent targets of treatment. The mechanisms of epileptogenicity of diffuse lower-grade gliomas are different: in addition to enhanced glutamatergic mechanisms, the isocitrate dehydrogenase (IDH) 1/2 mutations and their product D2-hydroxyglutarate (D2HG), which is structurally similar to glutamate, exerts excitatory effects on neurons also dependent on the presence of astrocytes. In preclinical models IDH1/2 inhibitors seem to impact both tumor growth and seizures. Conversely, the molecular factors behind the epileptogenicity of glioblastoma are unknown.

SUMMARY

This review summarizes the current state of molecular knowledge on epileptogenicity in gliomas and highlights the relationships between epileptogenicity and tumor growth.

Unexplained Causes of Glioma-Associated Epilepsies: A Review of Theories and an Area for Research

Approximately 30% of glioma patients are able to survive beyond one year postdiagnosis. And this short time is often overshadowed by glioma-associated epilepsy. This condition severely impairs the patient's quality of life and causes great suffering. The genetic, molecular and cellular mechanisms underlying tumour development and epileptogenesis remain incompletely understood, leading to numerous unanswered questions. The various types of gliomas, namely glioblastoma, astrocytoma and oligodendroglioma, demonstrate distinct seizure susceptibility and disease progression patterns. Patterns have been identified in the presence of IDH mutations and epilepsy, with tumour location in cortical regions, particularly the frontal lobe, showing a more frequent association with seizures. Altered expression of TP53, MGMT and VIM is frequently detected in tumour cells from individuals with epilepsy associated with glioma. However, understanding the pathogenesis of these modifications poses a challenge. Moreover, hypoxic effects induced by glioma and associated with the HIF-1a factor may have a significant impact on epileptogenesis, potentially resulting in epileptiform activity within neuronal networks. We additionally hypothesise about how the tumour may affect the functioning of neuronal ion channels and contribute to disruptions in the blood-brain barrier resulting in spontaneous depolarisations.

Differential metabolic alterations in IDH1 mutant vs. wildtype glioma cells promote epileptogenesis through distinctive mechanisms

Glioma-related epilepsy (GRE) is a hallmark clinical presentation of gliomas with significant impacts on patient quality of life. The current standard of care for seizure management is comprised of anti-seizure medications (ASMs) and surgical resection. Seizures in glioma patients are often drug-resistant and can often recur after surgery despite total tumor resection. Therefore, current research is focused on the pro-epileptic pathological changes occurring in tumor cells and the peritumoral environment. One important contribution to seizures in GRE patients is metabolic reprogramming in tumor and surrounding cells. This is most evident by the significantly heightened seizure rate in patients with isocitrate dehydrogenase mutated (IDHmut) tumors compared to patients with IDH wildtype (IDHwt) gliomas. To gain further insight into glioma metabolism in epileptogenesis, this review compares the metabolic changes inherent to IDHmut vs. IDHwt tumors and describes the pro-epileptic effects these changes have on both the tumor cells and the peritumoral environment. Understanding alterations in glioma metabolism can help to uncover novel therapeutic interventions for seizure management in GRE patients.

Seizure Management and Prophylaxis Considerations in Patients with Brain Tumors

PURPOSE OF REVIEW

The article gives an overview of the current knowledge in the management of tumor related epilepsy, including systematic reviews and consensus statements as well as recent insight into a potentially more individualized treatment approach.

RECENT FINDINGS

Tumor molecular markers as IDH1 mutation and MGMT methylation status may provide future treatment targets. Seizure control should be included as a metric in assessing efficacy of tumor treatment. Prophylactic treatment is recommended in all brain tumor patients after the first seizure. Epilepsy has a profound effect on the quality of life in this patient group. The clinician should tailor the choice of seizure prophylactic treatment to the individual patient, with the goal of limiting adverse effects, avoiding interactions and obtaining a high degree of seizure freedom. Status epilepticus is associated with inferior survival and must be treated promptly. A multidisciplinary team should treat patients with brain tumors and epilepsy.

Clinical updates on gliomas and implications of the 5th edition of the WHO classification of central nervous system tumors

Background

The 5th edition of the World Health Organization (WHO) classification of central nervous system tumors incorporated specific molecular alterations into the categorization of gliomas. The major revision of the classification scheme effectuates significant changes in the diagnosis and management of glioma. This study aimed to depict the clinical, molecular, and prognostic characteristics of glioma and its subtypes according to the current WHO classification.

Methods

Patients who underwent surgery for glioma at Peking Union Medical College Hospital during 11 years were re-examined for tumor genetic alterations using next-generation sequencing, polymerase chain reaction-based assay, and fluorescence in situ hybridization methods and enrolled in the analysis.

Results

The enrolled 452 gliomas were reclassified into adult-type diffuse glioma (ntotal=373; astrocytoma, n=78; oligodendroglioma, n=104; glioblastoma, n=191), pediatric-type diffuse glioma (ntotal=23; low-grade, n=8; high-grade, n=15), circumscribed astrocytic glioma (n=20), and glioneuronal and neuronal tumor (n=36). The composition, definition, and incidence of adult- and pediatric-type gliomas changed significantly between the 4th and the 5th editions of the classification. The clinical, radiological, molecular, and survival characteristics of each subtype of glioma were identified. Alterations in CDK4/6, CIC, FGFR2/3/4, FUBP1, KIT, MET, NF1, PEG3, RB1, and NTRK2 were additional factors correlated with the survival of different subtypes of gliomas.

Conclusions

The updated WHO classification based on histology and molecular alterations has updated our understanding of the clinical, radiological, molecular, survival, and prognostic characteristics of varied subtypes of gliomas and provided accurate guidance for diagnosis and potential prognosis for patients.

Antitumor Potential of Antiepileptic Drugs in Human Glioblastoma: Pharmacological Targets and Clinical Benefits

Glioblastoma (GBM) is characterized by fast-growing cells, genetic and phenotypic heterogeneity, and radio-chemo-therapy resistance, contributing to its dismal prognosis. Various medical comorbidities are associated with the natural history of GBM. The most disabling and greatly affecting patients' quality of life are neurodegeneration, cognitive impairment, and GBM-related epilepsy (GRE). Hallmarks of GBM include molecular intrinsic mediators and pathways, but emerging evidence supports the key role of non-malignant cells within the tumor microenvironment in GBM aggressive behavior. In this context, hyper-excitability of neurons, mediated by glutamatergic and GABAergic imbalance, contributing to GBM growth strengthens the cancer-nervous system crosstalk. Pathogenic mechanisms, clinical features, and pharmacological management of GRE with antiepileptic drugs (AEDs) and their interactions are poorly explored, yet it is a potentially promising field of research in cancer neuroscience. The present review summarizes emerging cooperative mechanisms in oncogenesis and epileptogenesis, focusing on the neuron-to-glioma interface. The main effects and efficacy of selected AEDs used in the management of GRE are discussed in this paper, as well as their potential beneficial activity as antitumor treatment. Overall, although still many unclear processes overlapping in GBM growth and seizure onset need to be elucidated, this review focuses on the intriguing targeting of GBM-neuron mutual interactions to improve the outcome of the so challenging to treat GBM.