Mark P. van Opijnen

The germline genetic susceptibility to adult glioblastoma remains unclear. With the option of broad molecular testing, it is crucial that clinicians are aware of the a priori probability of finding germline predisposition in glioblastoma patients. Here, we studied the genetic predisposition to adult glioblastoma using paired tumor-normal WGS data in an unselected, average cohort of 92 glioma WHO grade 4 patients. In 10 patients (11%), 12 Pathogenic Germline Variants (PGVs) were found in genes strongly associated with familial glioblastoma ( MSH6 (3x), PMS2 (5x), MSH2 , NF1 , BRCA1 ) or medulloblastoma ( SUFU ). In six of these patients (60%), causality was supported by a second (somatic) event and/or a matching genome-wide mutational signature. Thus, germline predisposition does play a role in the development of adult glioblastoma, with mismatch repair deficiency being the main mechanism. Our results also highlight the benefits of tumor-normal WGS for glioblastoma patients and their families, beyond identifying actionable mutations for therapy.

Key Clinical Message: This case shows the feasibility of targeted muscle reinnervation (TMR) in a patient with a traumatic neuroma of the medial antebrachial cutaneous nerve (MABCN). TMR was performed by connecting the proximal stump of the MABCN to the branch innervating the accessory epitrochleoanconeus muscle. Postoperatively, the patient reported significantly less pain.

For glioblastoma patients, the efficacy-targeted therapy is limited to date. Most of the molecular therapies previously studied are lacking efficacy in this population. More trials are needed to study the actual actionability of biomarkers in (recurrent) glioblastoma. This study aimed to assess the current clinical trial landscape to assess the role of molecular biomarkers in trials on recurrent glioblastoma treatment. The database ClinicalTrials.gov was used to identify not yet completed clinical trials on recurrent glioblastoma in adults. Recruiting studies were assessed to investigate the role of molecular criteria, which were retrieved as detailed as possible. Primary outcome was molecular criteria used as selection criteria for study participation. Next to this, details on moment and method of testing, and targets and drugs studied, were collected. In 76% (181/237) of the included studies, molecular criteria were not included in the study design. Of the remaining 56 studies, at least one specific genomic alteration as selection criterium for study participation was required in 33 (59%) studies. Alterations in EGFR, CDKN2A/B or C, CDK4/6, and RB were most frequently investigated, as were the corresponding drugs abemaciclib and ribociclib. Of the immunotherapies, CAR-T therapies were the most frequently studied therapies. Previously, genomics studies have revealed the presence of potentially actionable alterations in glioblastoma. Our study shows that the potential efficacy of targeted treatment is currently not translated into genome-driven trials in patients with recurrent glioblastoma. An intensification of genome-driven trials might help in providing evidence for (in)efficacy of targeted treatments.

Increased use of whole genome sequencing (WGS) in neuro-oncology for diagnostics and research purposes necessitates a renewed conversation about informed consent procedures and governance structures for sharing personal health data. There is currently no consensus on how to obtain informed consent for WGS in this population. In this narrative review, we analyze the formats and contents of frameworks suggested in literature for WGS in oncology and assess their benefits and limitations. We discuss applicability, specific challenges, and legal context for patients with (recurrent) glioblastoma. This population is characterized by the rarity of the disease, extremely limited prognosis, and the correlation of the stage of the disease with cognitive abilities. Since this has implications for the informed consent procedure for WGS, we suggest that the content of informed consent should be tailor-made for (recurrent) glioblastoma patients.

Purpose: Next generation sequencing (NGS) is an important tool used in clinical practice to obtain the required molecular information for accurate diagnostics of high-grade adult-type diffuse glioma (HGG). Since individual centers use either in-house produced or standardized panels, interlaboratory variation could play a role in the practice of HGG diagnosis and treatment. This study aimed to investigate the current practice in NGS application for both primary and recurrent HGG. Methods: This nationwide Dutch survey used the expertise of (neuro)pathologists and clinical scientists in molecular pathology (CSMPs) by sending online questionnaires on clinical and technical aspects. Primary outcome was an overview of panel composition in the different centers for diagnostic practice of HGG. Secondary outcomes included practice for recurrent HGG and future perspectives. Results: Out of twelve neuro-oncology centers, the survey was filled out by eleven (neuro)pathologists and seven CSMPs. The composition of the diagnostic NGS panels differed in each center with numbers of genes ranging from 12 to 523. Differences are more pronounced when tests are performed to find therapeutic targets in the case of recurrent disease: about half of the centers test for gene fusions (60%) and tumor mutational burden (40%). Conclusion: Current notable interlaboratory variations as illustrated in this study should be reduced in order to refine diagnostics and improve precision oncology. In-house developed tests, standardized panels and routine application of broad gene panels all have their own advantages and disadvantages. Future research would be of interest to study the clinical impact of variation in diagnostic approaches.

Background: Despite current best treatment options, a glioblastoma almost inevitably recurs after primary treatment. However, in the absence of clear evidence, current guidelines on recurrent glioblastoma are not well-defined. Re-resection is one of the possible treatment modalities, though it can be challenging to identify those patients who will benefit. Therefore, treatment decisions are made based on multidisciplinary discussions. This study aimed to investigate the current practice variation between neuro-oncology specialists. Methods: In this nationwide study among Dutch neuro-oncology specialists, we surveyed possible practice variation. Via an online survey, 4 anonymized recurrent glioblastoma cases were presented to neurosurgeons, neuro-oncologists, medical oncologists, and radiation oncologists in The Netherlands using a standardized questionnaire on whether and why they would recommend a re-resection or not. The results were used to provide a qualitative analysis of the current practice in The Netherlands. Results: The survey was filled out by 56 respondents, of which 15 (27%) were neurosurgeons, 26 (46%) neuro-oncologists, 2 (4%) medical oncologists, and 13 (23%) radiation oncologists. In 2 of the 4 cases, there appeared to be clinical equipoise. Overall, neurosurgeons tended to recommend re-resection more frequently compared to the other specialists. Neurosurgeons and radiation oncologists showed opposite recommendations in 2 cases. Conclusions: This study showed that re-resection of recurrent glioblastoma is subject to practice variation both between and within neuro-oncology specialties. In the absence of unambiguous guidelines, we observed a relationship between preferred practice and specialty. Reduction of this practice variation is important; to achieve this, adequate prospective studies are essential.

IDH1/2 wildtype (IDHwt) glioma WHO grade 2 and 3 patients with pTERT mutation and/or EGFR amplification and/or +7/−10 chromosome gain/loss have a similar overall survival time as IDHwt glioblastoma patients, and are both considered glioblastoma IDHwt according to the WHO 2021 classification. However, differences in seizure onset have been observed. This study aimed to compare the course of epilepsy in the two glioblastoma subtypes. We analyzed epilepsy data of an existing cohort including IDHwt histologically lower-grade glioma WHO grade 2 and 3 with molecular glioblastoma-like profile (IDHwt hLGG) and IDHwt glioblastoma patients. Primary outcome was the incidence proportion of epilepsy during the disease course. Major secondary outcomes included onset of epilepsy, number of seizure days and antiepileptic drug (AED) polytherapy. Out of 254 patients, 78% (50/64) IDHwt hLGG and 68% (129/190) IDHwt glioblastoma patients developed epilepsy during the disease course (p=0.121). Epilepsy onset before histopathological diagnosis occurred more frequently in IDHwt hLGG compared to IDHwt glioblastoma patients (90% versus 60%, p<0.001), with a significantly longer median time to diagnosis (3.5 versus 1.3 months, p<0.001). Median total seizure days was also longer for IDHwt hLGG patients (7.0 versus 3.0, p=0.005), and they received more often AED polytherapy (32% versus 17%, p=0.028). Although the incidence proportion of epilepsy during the entire disease course is similar, IDHwt hLGG patients show a significantly higher incidence of epilepsy before diagnosis and a significantly longer median time between first seizure and diagnosis compared to IDHwt glioblastoma patients, indicating a distinct clinical course.

Purpose: Optimal treatment with antiepileptic drugs (AEDs) is an important part of care for brain tumor patients with epileptic seizures. Lamotrigine and lacosamide are both examples of frequently used non-enzyme inducing AEDs with limited to no drug-drug interactions, reducing the risk of unfavorable side effects. This study aimed to compare the effectiveness of lamotrigine versus lacosamide. Methods: In this multicenter study we retrospectively analyzed data of patients with diffuse grade 2–4 glioma with epileptic seizures. All patients received either lamotrigine or lacosamide during the course of their disease after treatment failure of first-line monotherapy with levetiracetam or valproic acid. Primary outcome was the cumulative incidence of treatment failure, from initiation of lamotrigine or lacosamide, with death as competing event, for which a competing risk model was used. Secondary outcomes were uncontrolled seizures after AED initiation and level of toxicity. Results: We included a total of 139 patients of whom 61 (44%) used lamotrigine and 78 (56%) used lacosamide. At 12 months, there was no statistically significant difference in the cumulative incidence of treatment failure for any reason between lamotrigine and lacosamide: 38% (95%CI 26–51%) versus 30% (95%CI 20–41%), respectively. The adjusted hazard ratio for treatment failure of lacosamide compared to lamotrigine was 0.84 (95%CI 0.46–1.56). The cumulative incidences of treatment failure due to uncontrolled seizures (18% versus 11%) and due to adverse events (17% versus 19%) did not differ significantly between lamotrigine and lacosamide. Conclusion: Lamotrigine and lacosamide show similar effectiveness in diffuse glioma patients with epilepsy.

Purpose: Optimal treatment with antiepileptic drugs (AEDs) is an important part of care for brain tumor patients with epileptic seizures. Lamotrigine and lacosamide are both examples of frequently used non-enzyme inducing AEDs with limited to no drug-drug interactions, reducing the risk of unfavorable side effects. This study aimed to compare the effectiveness of lamotrigine versus lacosamide.Methods: In this multicenter study we retrospectively analyzed data of patients with diffuse grade 2-4 glioma with epileptic seizures. All patients received either lamotrigine or lacosamide during the course of their disease after treatment failure of first-line monotherapy with levetiracetam or valproic acid. Primary outcome was the cumulative incidence of treatment failure, from initiation of lamotrigine or lacosamide, with death as competing event, for which a competing risk model was used. Secondary outcomes were uncontrolled seizures after AED initiation and level of toxicity.Results: We included a total of 139 patients of whom 61 (44%) used lamotrigine and 78 (56%) used lacosamide. At 12 months, there was no statistically significant difference in the cumulative incidence of treatment failure for any reason between lamotrigine and lacosamide: 38% (95%CI: 26-51%) versus 30% (95%CI: 20-41%), respectively. The adjusted hazard ratio for treatment failure of lacosamide compared to lamotrigine was 0.84 (95%CI: 0.46-1.56). The cumulative incidences of treatment failure due to uncontrolled seizures (18% versus 11%) and due to adverse events (17% versus 19%) did not differ significantly between lamotrigine and lacosamide. Conclusion: Lamotrigine and lacosamide show similar effectiveness in diffuse glioma patients with epilepsy.