EANO guidelines on the diagnosis and treatment of diffuse gliomas of adulthood

Prescription preferences of antiepileptic drugs in brain tumor patients: An international survey among EANO members

Background

This study aimed at investigating antiepileptic drug (AED) prescription preferences in patients with brain tumor-related epilepsy (BTRE) among the European neuro-oncology community, the considerations that play a role when initiating AED treatment, the organization of care, and practices with regard to AED withdrawal.

Methods

A digital survey containing 31 questions about prescription preferences of AEDs was set out among members of the European Association of Neuro-Oncology (EANO).

Results

A total of 198 respondents treating patients with BTRE participated of whom 179 completed the entire survey. Levetiracetam was the first choice in patients with BTRE for almost all respondents (90% [162/181]). Levetiracetam was considered the most effective AED in reducing seizure frequency (72% [131/181]) and having the least adverse effects (48% [87/181]). Common alternatives for levetiracetam as equivalent first choice included lacosamide (33% [59/181]), lamotrigine (22% [40/181]), and valproic acid (21% [38/181]). Most crucial factors to choose a specific AED were potential adverse effects (82% [148/181]) and interactions with antitumor treatments (76% [137/181]). In the majority of patients, neuro-oncologists were involved in the treatment of seizures (73% [132/181])). Other relevant findings were that a minority of respondents ever prescribe AEDs in brain tumor patients without epilepsy solely as prophylaxis (29% [53/181]), but a majority routinely considers complete AED withdrawal in BTRE patients who are seizure-free after antitumor treatment (79% [141/179]).

Conclusions

Our results show that among European professionals treating patients with BTRE levetiracetam is considered the first choice AED, with the presumed highest efficacy and least adverse effects.

Temporal muscle thickness as a prognostic marker in newly diagnosed glioblastoma patients: translational imaging analysis of the CENTRIC EORTC 26071-22072 and CORE trials

PURPOSE

To investigate the prognostic relevance of temporal muscle thickness (TMT) as a surrogate parameter of skeletal muscle status in patients with newly diagnosed glioblastoma.

METHODS

We assessed TMT in cranial magnetic resonance images (MRI) of 755 patients enrolled in the CENTRIC EORTC 26071-22072 study (n=508) and CORE study (n=247). We used predefined sex-specific TMT cutoff values to categorize "patients at risk of sarcopenia" and "patients with normal muscle status" at baseline. Furthermore, we categorized patients according to the extent of TMT loss over time. Associations with progression-free survival (PFS) and overall survival (OS) were evaluated using the Cox model adjusted for other exploratory variables.

RESULTS

Patients at risk of sarcopenia (CENTRIC; n=158/508, 31.1%; CORE; n=87/247, 35.2%) at baseline had significantly higher risk of progression and death than patients with normal muscle status in both study cohorts (CENTRIC: PFS=HR 0.16, 95% CI: 0.12, 0.21, p<0.001; OS=HR 0.341, 95% CI: 0.27, 0.44, p < 0.001; CORE: PFS=HR 0.29, 95% CI: 0.21, 0.39, p<0.001; OS=HR 0.365, 95% CI: 0.27, 0.49, p<0.001). Similar results were obtained in multivariate Cox models adjusted for other important prognostic parameters. The extent of TMT loss over time showed a significant inverse correlation with median OS times in patients at risk for sarcopenia (CENTRIC: p<0.001, CORE: p=0.005), but not in patients with normal baseline muscle mass (CENTRIC: p=0.538, CORE: p=0.28).

CONCLUSION

TMT identifies ambulatory patients with newly diagnosed glioblastoma at risk for progressive sarcopenia and adverse outcomes. Early intervention may prevent skeletal muscle loss and improve patient outcome.

Molecular Features of Glioma Determined and Validated Using Combined TCGA and GTEx Data Analyses

Gliomas are among the most common intracranial tumors which originated from neuroepithelial cells. Increasing evidence has revealed that long noncoding RNA (lncRNA)-microRNA (miRNA)-mRNA module regulation and tumor-infiltrating immune cells play important regulatory roles in the occurrence and progression of gliomas. However, the precise underlying molecular mechanisms remain largely unknown. Data on gliomas in The Cancer Genome Atlas lack normal control samples; to overcome this limitation, we combined 665 The Cancer Genome Atlas glioma RNA sequence datasets with 188 Genotype-Tissue Expression normal brain RNA sequences to construct an expression matrix profile after normalization. We systematically analyzed the expression of mRNAs, lncRNAs, and miRNAs between gliomas and normal brain tissues. Kaplan–Meier survival analyses were conducted to screen differentially expressed mRNAs, lncRNAs, and miRNAs. A prognostic miRNA-related competitive endogenous RNA network was constructed, and the core subnetworks were filtered using 6 miRNAs, 3 lncRNAs, and 11 mRNAs. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses were performed to investigate the biological functions of significantly dysregulated mRNAs. Co-expression network analysis was performed to analyze and screen the core genes. Furthermore, single-sample Gene Set Enrichment Analysis and immune checkpoint gene expression analysis were performed, as co-expression analysis indicated immune gene dysregulation in glioma. Finally, the expression of representative dysregulated genes was validated in U87 cells at the transcriptional level, establishing a foundation for further research. We identified 7017 mRNAs, 437 lncRNAs, and 9 miRNAs that were differentially expressed in gliomas. Kaplan–Meier survival analysis revealed 5684 mRNAs, 61 lncRNAs, and 7 miRNAs with potential as prognostic signatures in patients with glioma. The hub subnetwork of the competing endogenous RNA network between PART1-hsa-mir-25-SLC12A5/TACC2/BSN/TLN2/ZDHHC8 was screened out. Gene co-expression network, single-sample Gene Set Enrichment Analysis, and immune checkpoint expression analysis demonstrated that tumor-infiltrating immune cells are closely related to gliomas. We identified novel potential biomarkers to predict survival and therapeutic targets for patients with gliomas based on a large-scale sample. Importantly, we filtered pivotal genes that provide valuable information for further exploration of the molecular mechanisms underlying glioma tumorigenesis and progression.

New Approaches to Glioblastoma

Faced with unique immunobiology and marked heterogeneity, treatment strategies for glioblastoma require therapeutic approaches that diverge from conventional oncological strategies. The selection and prioritization of targeted and immunotherapeutic strategies will need to carefully consider these features and companion biomarkers developed alongside treatment strategies to identify the appropriate patient populations. Novel clinical trial strategies that interrogate the tumor microenvironment for drug penetration and target engagement will inform go/no-go later-stage clinical studies. Innovative trial designs and analyses are needed to move effective agents toward regulatory approvals more rapidly. Expected final online publication date for the Annual Review of Medicine, Volume 73 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Optimal Combinations of Chemotherapy and Radiotherapy in Low-Grade Gliomas: A Mathematical Approach

Low-grade gliomas (LGGs) are brain tumors characterized by their slow growth and infiltrative nature. Treatment options for these tumors are surgery, radiation therapy and chemotherapy. The optimal use of radiation therapy and chemotherapy is still under study. In this paper, we construct a mathematical model of LGG response to combinations of chemotherapy, specifically to the alkylating agent temozolomide and radiation therapy. Patient-specific parameters were obtained from longitudinal imaging data of the response of real LGG patients. Computer simulations showed that concurrent cycles of radiation therapy and temozolomide could provide the best therapeutic efficacy in-silico for the patients included in the study. The patient cohort was extended computationally to a set of 3000 virtual patients. This virtual cohort was subject to an in-silico trial in which matching the doses of radiotherapy to those of temozolomide in the first five days of each cycle improved overall survival over concomitant radio-chemotherapy according to RTOG 0424. Thus, the proposed treatment schedule could be investigated in a clinical setting to improve combination treatments in LGGs with substantial survival benefits.

Tryptophan metabolism is inversely regulated in the tumor and blood of patients with glioblastoma

Tryptophan (Trp)-catabolic enzymes (TCEs) produce metabolites that activate the aryl hydrocarbon receptor (AHR) and promote tumor progression and immunosuppression in glioblastoma. As therapies targeting TCEs or AHR become available, a better understanding of Trp metabolism is required. Methods: The combination of LC-MS/MS with chemical isobaric labeling enabled the simultaneous quantitative comparison of Trp and its amino group-bearing metabolites in multiple samples. We applied this method to the sera of a cohort of 43 recurrent glioblastoma patients and 43 age- and sex-matched healthy controls. Tumor volumes were measured in MRI data using an artificial neural network-based approach. MALDI MSI visualized Trp and its direct metabolite N-formylkynurenine (FK) in glioblastoma tissue. Analysis of scRNA-seq data was used to detect the presence of Trp metabolism and AHR activity in different cell types in glioblastoma. Results: Compared to healthy controls, glioblastoma patients showed decreased serum Trp levels. Surprisingly, the levels of Trp metabolites were also reduced. The decrease became smaller with more enzymatic steps between Trp and its metabolites, suggesting that Trp availability controls the levels of its systemic metabolites. High tumor volume associated with low systemic metabolite levels and low systemic kynurenine levels associated with worse overall survival. MALDI MSI demonstrated heterogeneity of Trp catabolism across glioblastoma tissues. Analysis of scRNA-seq data revealed that genes involved in Trp metabolism were expressed in almost all the cell types in glioblastoma and that most cell types, in particular macrophages and T cells, exhibited AHR activation. Moreover, high AHR activity associated with reduced overall survival in the glioblastoma TCGA dataset. Conclusion: The novel techniques we developed could support the identification of patients that may benefit from therapies targeting TCEs or AHR activation.

Lower-Grade Gliomas: An Epidemiological Voxel-Based Analysis of Location and Proximity to Eloquent Regions

Background

Glioma is the most common intra-axial tumor, and its location relative to critical areas of the brain is important for treatment decision-making. Studies often report tumor location based on anatomical taxonomy alone since the estimation of eloquent regions requires considerable knowledge of functional neuroanatomy and is, to some degree, a subjective measure. An unbiased and reproducible method to determine tumor location and eloquence is desirable, both for clinical use and for research purposes.

Objective

To report on a voxel-based method for assessing anatomical distribution and proximity to eloquent regions in diffuse lower-grade gliomas (World Health Organization grades 2 and 3).

Methods

A multi-institutional population-based dataset of adult patients (≥18 years) histologically diagnosed with lower-grade glioma was analyzed. Tumor segmentations were registered to a standardized space where two anatomical atlases were used to perform a voxel-based comparison of the proximity of segmentations to brain regions of traditional clinical interest.

Results

Exploring the differences between patients with oligodendrogliomas, isocitrate dehydrogenase (IDH) mutated astrocytomas, and patients with IDH wild-type astrocytomas, we found that the latter were older, more often had lower Karnofsky performance status, and that these tumors were more often found in the proximity of eloquent regions. Eloquent regions are found slightly more frequently in the proximity of IDH-mutated astrocytomas compared to oligodendrogliomas. The regions included in our voxel-based definition of eloquence showed a high degree of association with performing biopsy compared to resection.

Conclusion

We present a simple, robust, unbiased, and clinically relevant method for assessing tumor location and eloquence in lower-grade gliomas.

Subventricular zone involvement is associated with worse outcome in glioma WHO grade 2 depending on molecular markers

Neural stem cells within the subventricular zone were identified as cells of origin driving growth of high-grade gliomas, and anatomical involvement of the subventricular zone has been associated with an inferior clinical outcome. Whether the association between poor outcome and subventricular zone involvement also applies to glioma of lower grades is unclear. We therefore analysed a retrospective cohort of 182 patients with glioma grade 2 (according to the WHO 2016 classification) including 78 individuals (43%) with subventricular zone involvement. Patients with and without subventricular zone involvement did not differ in regard to demographics, histopathology, and molecular markers. Notably, subventricular zone involvement was a negative prognostic marker for malignant progression and overall survival on uni- and multivariate analysis. When patients were stratified according to the cIMPACT-NOW update 6, subventricular zone involvement was negatively associated with outcome in IDH-wildtype astrocytomas and 1p19q-codeleted oligodendrogliomas but not in IDH-mutant astrocytomas. Collectively, subventricular zone involvement may represent a risk factor for worse outcome in glioma WHO grade 2 depending on the molecular tumor signature. The present data confirm the relevance of molecular glioma classifications as proposed by the cIMPACT-NOW update 6. These findings warrant evaluation in prospective cohorts.

Rationally designed drug delivery systems for the local treatment of resected glioblastoma

Glioblastoma (GBM) is a particularly aggressive brain cancer associated with high recurrence and poor prognosis. The standard of care, surgical resection followed by concomitant radio- and chemotherapy, leads to low survival rates. The local delivery of active agents within the tumor resection cavity has emerged as an attractive means to initiate oncological treatment immediately post-surgery. This complementary approach bypasses the blood-brain barrier, increases the local concentration at the tumor site while reducing or avoiding systemic side effects. This review will provide a global overview on the local treatment for GBM with an emphasis on the lessons learned from past clinical trials. The main parameters to be considered to rationally design fit-of-purpose biomaterials and develop drug delivery systems for local administration in the GBM resection cavity to prevent the tumor recurrence will be described. The intracavitary local treatment of GBM should i) use materials that facilitate translation to the clinic; ii) be characterized by easy GMP effective scaling up and easy-handling application by the neurosurgeons; iii) be adaptable to fill the tumor-resected niche, mold to the resection cavity or adhere to the exposed brain parenchyma; iv) be biocompatible and possess mechanical properties compatible with the brain; v) deliver a therapeutic dose of rationally-designed or repurposed drug compound(s) into the GBM infiltrative margin. Proof of concept with high translational potential will be provided. Finally, future perspectives to facilitate the clinical translation of the local perisurgical treatment of GBM will be discussed.

Advances in the management of glioblastoma

Glioblastoma (GB) is the most common and most malignant primary brain tumour in adults. Despite much effort, gold standard therapy has not changed since the introduction of adjuvant temozolomide in 2005 and prognosis remains poor. Despite this, there has been significant improvement in the surgical technology and technique, that has allowed for increased rates of safe maximal resection of the tumour. In addition, our increased knowledge of the biology of GB has revealed more potential targets, especially in the field of immunotherapy, which has been successful in revolutionising treatment of other cancers. We review the current best practice for the treatment of GB and explore some of the more recent advances in GB management from both a surgical and molecular therapeutic perspective.

Glioma-Targeted Therapeutics: Computer-Aided Drug Design Prospective

Amongst the several types of brain cancers known to humankind, glioma is one of the most severe and life-threatening types of cancer, comprising 40% of all primary brain tumors. Recent reports have shown the incident rate of gliomas to be 6 per 100,000 individuals per year globally. Despite the various therapeutics used in the treatment of glioma, patient survival rate remains at a median of 15 months after undergoing first-line treatment including surgery, radiation, and chemotherapy with Temozolomide. As such, the discovery of newer and more effective therapeutic agents is imperative for patient survival rate. The advent of computer-aided drug design in the development of drug discovery has emerged as a powerful means to ascertain potential hit compounds with distinctively high therapeutic effectiveness against glioma. This review encompasses the recent advances of bio-computational in-silico modeling that have elicited the discovery of small molecule inhibitors and/or drugs against various therapeutic targets in glioma. The relevant information provided in this report will assist researchers, especially in the drug design domains, to develop more effective therapeutics against this global disease.

Extracellular vesicles: the key for precision medicine in glioblastoma

Glioblastoma (GBM) represents the most aggressive and lethal disease of the central nervous system. Diagnosis is delayed following the occurrence of symptoms, and treatment is based on standardized approaches that are unable to cope with its heterogeneity, mutability, and invasiveness. The follow-up of patients relies on burdensome schedules for magnetic resonance imaging (MRI). However, to personalize treatment, biomarkers and liquid biopsy still represent unmet clinical needs. Extracellular vesicles (EVs) may be the key to revolutionize the entire process of care for patients with GBM. EVs can be collected noninvasively (eg, blood) and impressively possess multilayered information, which is constituted by their concentration and molecular cargo. EV-based liquid biopsy may facilitate GBM diagnosis and enable the implementation of personalized treatment, resulting in customized care for each patient and for each analyzed time point of the disease, thereby tackling the distinctive heterogeneity and mutability of GBM that confounds effective treatment. Herein, we discuss the limitations of current GBM treatment options and the rationale behind the need for personalized care. We also review the evidence supporting GBM-associated EVs as a promising tool capable of fulfilling the still unmet clinical need for effective and timely personalized care of patients with GBM.

Dynamic Interplay between Lower-Grade Glioma Instability and Brain Metaplasticity: Proposal of an Original Model to Guide the Therapeutic Strategy

The behavior of lower-grade glioma (LGG) is changing over time, spontaneously, and in reaction to treatments. First, due to genomic instability and clonal expansion, although LGG progresses slowly during the early period of the disease, its growth velocity will accelerate when this tumor will transform to a higher grade of malignancy. Furthermore, its pattern of progression may change following therapy, e.g., by switching from a proliferative towards a more diffuse profile, in particular after surgical resection. In parallel to this plasticity of the neoplasm, the brain itself is constantly adapting to the tumor and possible treatment(s) thanks to reconfiguration within and between neural networks. Furthermore, the pattern of reallocation can also change, especially by switching from a perilesional to a contrahemispheric functional reorganization. Such a reorientation of mechanisms of cerebral reshaping, related to metaplasticity, consists of optimizing the efficiency of neural delocalization in order to allow functional compensation by adapting over time the profile of circuits redistribution to the behavioral modifications of the glioma. This interplay between LGG mutations and reactional connectomal instability leads to perpetual modulations in the glioma-neural equilibrium, both at ultrastructural and macroscopic levels, explaining the possible preservation of quality of life despite tumor progression. Here, an original model of these dynamic interactions across LGG plasticity and the brain metanetwork is proposed to guide a tailored step-by-step individualized therapeutic strategy over years. Integration of these new parameters, not yet considered in the current guidelines, might improve management of LGG patients.

Efficacy of osimertinib plus bevacizumab in glioblastoma patients with simultaneous EGFR amplification and EGFRvIII mutation

BACKGROUND

Amplification of EGFR and its active mutant EGFRvIII are common in glioblastoma (GB). While EGFR and EGFRvIII play critical roles in pathogenesis, targeted therapy with EGFR-tyrosine kinase inhibitors or antibodies has shown limited efficacy. To improve the likelihood of effectiveness, we targeted adult patients with recurrent GB enriched for simultaneous EGFR amplification and EGFRvIII mutation, with osimertinib/bevacizumab at doses described for non-small cell lung cancer.

METHODS

We retrospectively explored whether previously described EGFRvIII mutation in association with EGFR gene amplification could predict response to osimertinib/bevacizumab combination in a subset of 15 patients treated at recurrence. The resistance pattern in a subgroup of subjects is described using a commercial next-generation sequencing panel in liquid biopsy.

RESULTS

There were ten males (66.7%), and the median patient's age was 56 years (range 38-70 years). After their initial diagnosis, 12 patients underwent partial (26.7%) or total resection (53.3%). Subsequently, all cases received IMRT and concurrent and adjuvant temozolomide (TMZ; the median number of cycles 9, range 6-12). The median follow-up after recurrence was 17.1 months (95% CI 12.3-22.6). All patients received osimertinib/bevacizumab as a second-line intervention with a median progression-free survival (PFS) of 5.1 months (95% CI 2.8-7.3) and overall survival of 9.0 months (95% CI 3.9-14.0). The PFS6 was 46.7%, and the overall response rate was 13.3%. After exposure to the osimertinib/bevacizumab combination, the main secondary alterations were MET amplification, STAT3, IGF1R, PTEN, and PDGFR.

CONCLUSIONS

While the osimertinib/bevacizumab combination was marginally effective in most GB patients with simultaneous EGFR amplification plus EGFRvIII mutation, a subgroup experienced a long-lasting meaningful benefit. The findings of this brief cohort justify the continuation of the research in a clinical trial. The pattern of resistance after exposure to osimertinib/bevacizumab includes known mechanisms in the regulation of EGFR, findings that contribute to the understanding and targeting in a stepwise rational this pathway.

Psychological Distress in Intracranial Neoplasia: A Comparison of Patients With Benign and Malignant Brain Tumours

Objective: We aimed to assess psychological distress in patients with intracranial neoplasia, a group of patients who suffer from severe functional, neurocognitive and neuropsychological side effects, resulting in high emotional distress. Methods: We conducted a cross-sectional study, including inpatients with brain tumours. Eligible patients completed validated self-report questionnaires measuring depression, anxiety, distress, symptoms of posttraumatic stress disorder (PTSD), fear of progression and health-related quality of life. The questionnaire set was completed after brain surgery and receiving diagnosis and before discharge from hospital. Results: A total of n = 31 patients participated in this survey. Fourteen of them suffered from malignant (n = 3 metastatic neoplasia) and 17 from benign brain tumours. Mean values of the total sample regarding depression (M = 9.28, SD = 6.08) and anxiety (M = 6.00, SD = 4.98) remained below the cut-off ≥ 10. Mean psychosocial distress (M = 16.30, SD = 11.23, cut-off ≥ 14) and posttraumatic stress (M = 35.10, SD = 13.29, cut-off ≥ 32) exceeded the clinically relevant cut-off value in all the patients with intracranial tumours. Significantly, more patients with malignant (79%) than benign (29%) brain tumours reported PTSD symptoms (p = 0.006). Conclusion: Distress and clinically relevant PTSD symptoms in patients with intracranial neoplasia should be routinely screened and treated in psycho-oncological interventions immediately after diagnosis. Especially, neuro-oncological patients with malignant brain tumours or metastases need targeted support to reduce their emotional burden.

[Brain tumor immunotherapy-Possibilities and challenges of personalization]

Brain tumors represent a special interdisciplinary challenge in the treatment of neurological disorders. Insights into the interindividual as well as the spatial and temporal intraindividual heterogeneity require entirely new personalized treatment approaches. Particularly in the field of immunotherapy there are possibilities for targeted interventions and systematic follow-up for assessment of response to treatment. Although not yet integrated into the standard treatment, early clinical trials in recent years have shown the feasibility of systematic personalized treatment approaches. The conceptual and regulatory implications of these approaches reach far beyond the field of neuro-oncology.

Age is associated with unfavorable neuropathological and radiological features and poor outcome in patients with WHO grade 2 and 3 gliomas

With the rising life expectancy and availability of neuroimaging, increased number of older patients will present with diffuse and anaplastic gliomas. The aim of our study was therefore to investigate age-related prognostic clinical, neuropathological and radiological features of lower-grade gliomas. All consecutive patients with diffuse or anaplastic glioma WHO grade 2 and 3 who underwent first tumor resection between 2010 and 2018, were selected from the institutional neuro-oncological database and evaluated. The mean age of 55 males and 44 females was 46 years (SD ± 16). Wild-type IDH1 (p = 0.012), persistent nuclear ATRX expression (p = 0.012) and anaplasia (p < 0.001) were significantly associated with higher age. The CE volume before resection was found to be increased in older patients (r = 0.42, p < 0.0001), and CE rate was higher in the IDH wild-type population only (p = 0.02). The extent of resection did not differ with age. Overall, one year of life resulted in a PFS reduction of 9 days (p = 0.047); in IDH sub-group analysis, this dependency was confirmed only in wild-type tumors (p = 0.05). OS was significantly reduced in older patients (p = 0.033). In conclusion, behavior and prognosis of WHO grade 2 and 3 glioma were unfavorable in correlation to patient’s age, even if the extent of resection was comparable. Older age imparted a poorer PFS and higher CE rate only in the IDH wild-type population.

Radiotherapy for glioblastoma patients with poor performance status

Purpose

There is limited information on treatment recommendations for glioblastoma patients with poor performance status. Here, we aim to evaluate the association of radiotherapy on survival in glioblastoma patients presenting with poor postoperative performance status in first-line setting.

Methods

We retrospectively analyzed data of 93 glioblastoma patients presenting with poor postoperative performance status (ECOG 2–4) at the University Hospital Zurich, Switzerland, in the years 2005–2019. A total of 43 patients received radiotherapy with or without systemic therapy in the first-line setting, whereas 50 patients received no additive local or systemic treatment after initial biopsy or resection. Overall survival was calculated from primary diagnosis and from the end of radiotherapy. In addition, factors influencing survival were analyzed.

Results

Median overall survival from primary diagnosis was 6.2 months in the radiotherapy group (95% CI 6.2–14.8 weeks, range 2–149 weeks) and 2.3 months in the group without additive treatment (95% CI 1.3–7.4 weeks, range 0–28 weeks) (p < 0.001). This survival benefit was confirmed by landmark analyses. Factors associated with overall survival were extent of resection and administration of radiotherapy with or without systemic treatment. Median survival from end of radiotherapy was 3 months (95% CI 4.3–21.7 weeks, range 0–72 weeks), with 25.6% (n = 11) early termination of treatment and 83.7% (n = 36) requiring radiotherapy as in-patients. Performance status improved in 27.9% (n = 12) of patients after radiotherapy.

Conclusion

In this retrospective single-institution analysis, radiotherapy improved overall survival in patients with poor performance status, especially in patients who were amendable to neurosurgical resection.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00432-021-03770-9.

TRIM28 Selective Nanobody Reduces Glioblastoma Stem Cell Invasion

Glioblastoma (GB), is the most common and aggressive malignant primary brain tumour in adults. Intra- and inter-tumour heterogeneity, infiltrative GB cell invasion and presence of therapy-resistant GB stem cells (GSCs) represent major obstacles to favourable prognosis and poor therapy response. Identifying the biomarkers of the most aggressive tumour cells and their more efficient targeting strategies are; therefore, crucial. Recently, transcription factor TRIM28 has been identified as a GB biomarker and, in this study, we have shown high expression of TRIM28 in GB and in low grade gliomas as well as higher expression in GSCs vs. differentiated GB cells, although in both cases not significant. We demonstrated significant in vitro inhibition of GB cells and GSCs invasiveness and spread in zebrafish brains in vivo by anti-TRIM28 selective nanobody NB237. TRIM28 was also enriched in GB (tumour) core and associated with the expression of stem cell genes, but was not prognostic for overall survival. However, based on the above results, we conclude that TRIM28 nanobody NB237 offers a new opportunity as a GB therapeutic tool.

Radiotherapy of High-Grade Gliomas: First Half of 2021 Update with Special Reference to Radiosensitization Studies

Albeit the effort to develop targeted therapies for patients with high-grade gliomas (WHO grades III and IV) is evidenced by hundreds of current clinical trials, radiation remains one of the few effective therapeutic options for them. This review article analyzes the updates on the topic "radiotherapy of high-grade gliomas" during the period 1 January 2021-30 June 2021. The high number of articles retrieved in PubMed using the search terms ("gliom* and radio*") and manually selected for relevance indicates the feverish research currently ongoing on the subject. During the last semester, significant advances were provided in both the preclinical and clinical settings concerning the diagnosis and prognosis of high-grade gliomas, their radioresistance, and the inevitable side effects of their treatment with radiation. The novel information concerning tumor radiosensitization was of special interest in terms of therapeutic perspective and was discussed in detail.

Vorasidenib, a Dual Inhibitor of Mutant IDH1/2, in Recurrent or Progressive Glioma; Results of a First-in-Human Phase I Trial

PURPOSE

Lower grade gliomas (LGGs) are malignant brain tumors. Current therapy is associated with short- and long-term toxicity. Progression to higher tumor grade is associated with contrast enhancement on MRI. The majority of LGGs harbor mutations in the genes encoding isocitrate dehydrogenase 1 or 2 (IDH1/IDH2). Vorasidenib (AG-881) is a first-in-class, brain-penetrant, dual inhibitor of the mutant IDH1 and mutant IDH2 enzymes.

PATIENTS AND METHODS

We conducted a multicenter, open-label, phase I, dose-escalation study of vorasidenib in 93 patients with mutant IDH1/2 (mIDH1/2) solid tumors, including 52 patients with glioma that had recurred or progressed following standard therapy. Vorasidenib was administered orally, once daily, in 28-day cycles until progression or unacceptable toxicity. Enrollment is complete; this trial is registered with ClinicalTrials.gov, NCT02481154.

RESULTS

Vorasidenib showed a favorable safety profile in the glioma cohort. Dose-limiting toxicities of elevated transaminases occurred at doses ≥100 mg and were reversible. The protocol-defined objective response rate per Response Assessment in Neuro-Oncology criteria for LGG in patients with nonenhancing glioma was 18% (one partial response, three minor responses). The median progression-free survival was 36.8 months [95% confidence interval (CI), 11.2-40.8] for patients with nonenhancing glioma and 3.6 months (95% CI, 1.8-6.5) for patients with enhancing glioma. Exploratory evaluation of tumor volumes in patients with nonenhancing glioma showed sustained tumor shrinkage in multiple patients.

CONCLUSIONS

Vorasidenib was well tolerated and showed preliminary antitumor activity in patients with recurrent or progressive nonenhancing mIDH LGG.

The 3.0 Cell Communication: New Insights in the Usefulness of Tunneling Nanotubes for Glioblastoma Treatment

Simple Summary

Communication between cells helps tumors acquire resistance to chemotherapy and makes the struggle against cancer more challenging. Tunneling nanotubes (TNTs) are long channels able to connect both nearby and distant cells, contributing to a more malignant phenotype. This finding might be useful in designing novel strategies of drug delivery exploiting these systems of connection. This would be particularly important to reach tumor niches, where glioblastoma stem cells proliferate and provoke immune escape, thereby increasing metastatic potential and tumor recurrence a few months after surgical resection of the primary mass. Along with the direct inhibition of TNT formation, TNT analysis, and targeting strategies might be useful in providing innovative tools for the treatment of this tumor.

Abstract

Glioblastoma (GBM) is a particularly challenging brain tumor characterized by a heterogeneous, complex, and multicellular microenvironment, which represents a strategic network for treatment escape. Furthermore, the presence of GBM stem cells (GSCs) seems to contribute to GBM recurrence after surgery, and chemo- and/or radiotherapy. In this context, intercellular communication modalities play key roles in driving GBM therapy resistance. The presence of tunneling nanotubes (TNTs), long membranous open-ended channels connecting distant cells, has been observed in several types of cancer, where they emerge to steer a more malignant phenotype. Here, we discuss the current knowledge about the formation of TNTs between different cellular types in the GBM microenvironment and their potential role in tumor progression and recurrence. Particularly, we highlight two prospective strategies targeting TNTs as possible therapeutics: (i) the inhibition of TNT formation and (ii) a boost in drug delivery between cells through these channels. The latter may require future studies to design drug delivery systems that are exchangeable through TNTs, thus allowing for access to distant tumor niches that are involved in tumor immune escape, maintenance of GSC plasticity, and increases in metastatic potential.

Multicenter DSC-MRI-Based Radiomics Predict IDH Mutation in Gliomas

Simple Summary

Significant efforts have been put toward developing MRI-based radiogenomics for IDH status subtyping predictions; however, in the vast majority of these approaches, the external validation sets are absent. Another limitation in current studies is the lack of explainability in radiomics models, which hampers clinical trust and translation. Motivated by these challenges, we proposed a multicenter DSC–MRI-based radiomics study based on an independent exploratory set, which was externally validated on two independent cohorts, for IDH mutation status prediction. Our results demonstrated that DSC–MRI radiogenomics in gliomas, coupled with dynamic-based image standardization techniques, hold the potential to provide (a) increased predictive performance by offering models that generalize well, (b) reasoning behind the IDH mutation status predictions, and (c) interpretability of the radiomics features’ impacts in model performance.

Abstract

To address the current lack of dynamic susceptibility contrast magnetic resonance imaging (DSC–MRI)-based radiomics to predict isocitrate dehydrogenase (IDH) mutations in gliomas, we present a multicenter study that featured an independent exploratory set for radiomics model development and external validation using two independent cohorts. The maximum performance of the IDH mutation status prediction on the validation set had an accuracy of 0.544 (Cohen’s kappa: 0.145, F1-score: 0.415, area under the curve-AUC: 0.639, sensitivity: 0.733, specificity: 0.491), which significantly improved to an accuracy of 0.706 (Cohen’s kappa: 0.282, F1-score: 0.474, AUC: 0.667, sensitivity: 0.6, specificity: 0.736) when dynamic-based standardization of the images was performed prior to the radiomics. Model explainability using local interpretable model-agnostic explanations (LIME) and Shapley additive explanations (SHAP) revealed potential intuitive correlations between the IDH–wildtype increased heterogeneity and the texture complexity. These results strengthened our hypothesis that DSC–MRI radiogenomics in gliomas hold the potential to provide increased predictive performance from models that generalize well and provide understandable patterns between IDH mutation status and the extracted features toward enabling the clinical translation of radiogenomics in neuro-oncology.

Red blood cell distribution width to platelet ratio substantiates preoperative survival prediction in patients with newly-diagnosed glioblastoma

Object

The conception of individual patient-adjusted treatment strategies is constantly emerging in the field of neuro-oncology. Systemic laboratory markers may allow insights into individual needs and estimated treatment benefit at an earliest possible stage. Therefore, the present study was aimed at analyzing the prognostic significance of preoperative routine laboratory values in patients with newly-diagnosed glioblastoma.

Methods

Between 2014 and 2019, 257 patients were surgically treated for newly-diagnosed glioblastoma at the Neuro-Oncology Center of the University Hospital Bonn. Preoperative routine laboratory values including red blood cell distribution width (RDW) and platelet count were reviewed. RDW to platelet count ratio (RPR) was calculated and correlated to overall survival (OS) rates.

Results

Median preoperative RPR was 0.053 (IQR 0.044–0.062). The receiver operating characteristic (ROC) curve indicated an optimal cut-off value for RPR to be 0.05 (AUC 0.62; p = 0.002, 95% CI 0.544–0.685). 101 patients (39%) presented with a preoperative RPR < 0.05, whereas 156 patients (61%) had a RPR ≥ 0.05. Patients with preoperative RPR < 0.05 exhibited a median OS of 20 months (95% CI 17.9–22.1), which was significantly higher compared to a median OS of 13 months (95% CI 10.9–15.1) in patients with preoperative RPR ≥ 0.05 (p < 0.001).

Conclusions

The present study suggests the RPR to constitute a novel prognostic inflammatory marker for glioblastoma patients in the course of preoperative routine laboratory examinations and might contribute to a personalized medicine approach.

Prognostic factors in adult brainstem glioma: a tertiary care center analysis and review of the literature

Introduction

Adult brainstem gliomas (BSGs) are rare central nervous system tumours characterized by a highly heterogeneous clinical course. Median survival times range from 11 to 84 months. Beyond surgery, no treatment standard has been established. We investigated clinical and radiological data to assess prognostic features providing support for treatment decisions.

Methods

34 BSG patients treated between 2000 and 2019 and aged ≥ 18 years at the time of diagnosis were retrospectively identified from the databases of the two largest Austrian Neuro-Oncology centres. Clinical data including baseline characteristics, clinical disease course, applied therapies, the outcome as well as neuroradiological and neuropathological findings were gathered and analysed. The tumour apparent diffusion coefficient (ADC), volumetry of contrast-enhancing and non-contrast-enhancing lesions were determined on magnetic resonance imaging scans performed at diagnosis.

Results

The median age at diagnosis was 38.5 years (range 18–71 years). Tumour progression occurred in 26/34 (76.5%) patients after a median follow up time of 19 months (range 0.9–236.2). Median overall survival (OS) and progression-free survival (PFS) was 24.1 months (range 0.9–236.2; 95% CI 18.1–30.1) and 14.5 months (range 0.7–178.5; 95% CI 5.1–23.9), respectively. Low-performance status, high body mass index (BMI) at diagnosis and WHO grading were associated with shorter PFS and OS at univariate analysis (p < 0.05, log rank test, respectively). ADC values below the median were significantly associated with shorter OS (14.9 vs 44.2 months, p = 0.018).

Conclusion

ECOG, BMI, WHO grade and ADC values were associated with the survival prognosis of BSG patients and should be included in the prognostic assessment.

APLN/APLNR Signaling Controls Key Pathological Parameters of Glioblastoma

Simple Summary

The neurovascular peptide Apelin and its receptor APLNR are upregulated during glioblastoma pathology. Here we summarize their role in the brain tumor microenvironment composed of neurons, astrocytes, and the vascular and immune systems. Targeting APLN/APLNR signaling promises to unfold multimodal actions in future GBM therapy, acting as an anti-angiogenic and an anti-invasive treatment, and offering the possibility to reduce neurological symptoms and increase overall survival simultaneously.

Abstract

Glioblastoma (GBM) is the most common and aggressive primary brain tumor in adults. GBM-expansion depends on a dense vascular network and, coherently, GBMs are highly angiogenic. However, new intratumoral blood vessels are often aberrant with consequences for blood-flow and vascular barrier function. Hence, the delivery of chemotherapeutics into GBM can be compromised. Furthermore, leaky vessels support edema-formation, which can result in severe neurological deficits. The secreted signaling peptide Apelin (APLN) plays an important role in the formation of GBM blood vessels. Both APLN and the Apelin receptor (APLNR) are upregulated in GBM cells and control tumor cell invasiveness. Here we summarize the current evidence on the role of APLN/APLNR signaling during brain tumor pathology. We show that targeting APLN/APLNR can induce anti-angiogenic effects in GBM and simultaneously blunt GBM cell infiltration. In addition, we discuss how manipulation of APLN/APLNR signaling in GBM leads to the normalization of tumor vessels and thereby supports chemotherapy, reduces edema, and improves anti-tumorigenic immune reactions. Hence, therapeutic targeting of APLN/APLNR signaling offers an interesting option to address different pathological hallmarks of GBM.

Glioblastoma: Emerging Treatments and Novel Trial Designs

Simple Summary

Nowadays, very few systemic agents have shown clinical activity in patients with glioblastoma, making the research of novel therapeutic approaches a critical issue. Fortunately, the availability of novel compounds is increasing thanks to better biological knowledge of the disease. In this review we want to investigate more promising ongoing clinical trials in both primary and recurrent GBM. Furthermore, a great interest of the present work is focused on novel trial design strategies.

Abstract

Management of glioblastoma is a clinical challenge since very few systemic treatments have shown clinical efficacy in recurrent disease. Thanks to an increased knowledge of the biological and molecular mechanisms related to disease progression and growth, promising novel treatment strategies are emerging. The expanding availability of innovative compounds requires the design of a new generation of clinical trials, testing experimental compounds in a short time and tailoring the sample cohort based on molecular and clinical behaviors. In this review, we focused our attention on the assessment of promising novel treatment approaches, discussing novel trial design and possible future fields of development in this setting.

Comparing Tumor Cell Invasion and Myeloid Cell Composition in Compatible Primary and Relapsing Glioblastoma

Simple Summary

We established a new minimally invasive mouse model for GBM relapse. For this, we utilized orthotopical implantation of HSVTK-transduced GBM cells and pharmacological treatment with GCV. In addition, we implanted patient-derived GBM cells of primary or recurrent tumors. We found that recurrent GBM were more aggressively invasive than primary GBM. Moreover, the recurring tumors had a higher ratio of monocyte-derived macrophages among the entire population of tumor associated myeloid cells. This shift in the composition of tumor-associated immune cells appeared to be independent from cell-death signaling or surgical intervention. This model provides the means to investigate the entire process of tumor relapse and test standard as well as experimental therapeutic strategies for relapsing GBM under defined conditions.

Abstract

Glioblastoma (GBM) recurrence after treatment is almost inevitable but addressing this issue with adequate preclinical models has remained challenging. Here, we introduce a GBM mouse model allowing non-invasive and scalable de-bulking of a tumor mass located deeply in the brain, which can be combined with conventional therapeutic approaches. Strong reduction of the GBM volume is achieved after pharmacologically inducing a tumor-specific cell death mechanism. This is followed by GBM re-growth over a predictable timeframe. Pharmacological de-bulking followed by tumor relapse was accomplished with an orthotopic mouse glioma model. Relapsing experimental tumors recapitulated pathological features often observed in recurrent human GBM, like increased invasiveness or altered immune cell composition. Orthotopic implantation of GBM cells originating from biopsies of one patient at initial or follow-up treatment reproduced these findings. Interestingly, relapsing GBM of both models contained a much higher ratio of monocyte-derived macrophages (MDM) versus microglia than primary GBM. This was not altered when combining pharmacological de-bulking with invasive surgery. We interpret that factors released from viable primary GBM cells preferentially attract microglia whereas relapsing tumors preponderantly release chemoattractants for MDM. All in all, this relapse model has the capacity to provide novel insights into clinically highly relevant aspects of GBM treatment.

Pathways of follow-up care in an Italian center: retrospective study on patients with gliomas II and III

INTRODUCTION

Glioma is the most common primary brain cancer in adults. Long-term and progression-free survivals are dependent on the type and grade of glioma, as well as on the extent of resection and postoperative treatments. In Italy, it is unclear how long follow-up care should last and whether the primary care sector is either willing or able to take this on. The aim is to determine pathways of follow-up care and evaluate the professional attitude of doctors to prescribe to patient visits and exams after surgery.

METHODS

A retrospective study was performed on patients with glioma II and III who underwent surgery at tertiary care Neurological Institute Besta of Milan (FINCB) from 2012 to 2020. Data were collected through electronic medical records and inserted in an ad hoc developed database.

RESULTS

Three pathways have been identified: a common preliminary pathway (from the pre-operative visit to surgery) for all patients undergoing surgery for gliomas II and III and two follow-up pathways (with or without second surgery).

CONCLUSIONS

FINCB has developed care pathways that are sometimes personalized according to the doctor's expertise and attitude to prescribe new examinations. Given the lack of guidelines on this issue, we can cautiously conclude that it is necessary to identify whether, in addition to standard care, personalized supportive care intervention and pathway plan can significantly improve patients' outcome.

The Multifaceted Role of Extracellular Vesicles in Glioblastoma: microRNA Nanocarriers for Disease Progression and Gene Therapy

Glioblastoma (GB) is the most aggressive form of brain cancer in adults, characterized by poor survival rates and lack of effective therapies. MicroRNAs (miRNAs) are small, non-coding RNAs that regulate gene expression post-transcriptionally through specific pairing with target messenger RNAs (mRNAs). Extracellular vesicles (EVs), a heterogeneous group of cell-derived vesicles, transport miRNAs, mRNAs and intracellular proteins, and have been shown to promote horizontal malignancy into adjacent tissue, as well as resistance to conventional therapies. Furthermore, GB-derived EVs have distinct miRNA contents and are able to penetrate the blood-brain barrier. Numerous studies have attempted to identify EV-associated miRNA biomarkers in serum/plasma and cerebrospinal fluid, but their collective findings fail to identify reliable biomarkers that can be applied in clinical settings. However, EVs carrying specific miRNAs or miRNA inhibitors have great potential as therapeutic nanotools in GB, and several studies have investigated this possibility on in vitro and in vivo models. In this review, we discuss the role of EVs and their miRNA content in GB progression and resistance to therapy, with emphasis on their potential as diagnostic, prognostic and disease monitoring biomarkers and as nanocarriers for gene therapy.

Does positive MGMT methylation outbalance the limitation of subtotal resection in glioblastoma IDH-wildtype patients?

Background

The impact on survival of complete resection (CR) in patients with malignant glioma and MGMT promoter methylation on adjuvant therapy strategies has been proven in the past. However, it is not known whether a MGMT promoter methylation can compensate a subtotal resection. Therefore, we analyzed the progress of postoperative residual tumor tissue depending on the molecular tumor status.

Methods

We included all glioblastoma, IDH-wildtype (WHO grade IV) patients with postoperative residual tumor tissue, who were treated at our neurooncological department between 2010 and 2018. Correlation of molecular patterns with clinical data and survival times was performed. The results were compared to patients following CR.

Results

267 patients with glioblastoma, IDH-wildtype (WHO grade IV) received surgery of whom 81 patients with residual tumor were included in the analysis. MGMT promoter was methylated in 31 patients (38.27%). Median OS and PFS were significantly increased in patients with methylated MGMT promoter (mOS: 16 M vs. 13 M, p = 0.009; mPFS: 13 M vs. 5 M, p = 0.003). In comparison to survival of patients following CR, OS was decreased in patients with residual tumor regardless MGMT methylation.

Conclusion

Our data confirm impact of MGMT promoter methylation in patients with glioblastoma, IDH-wildtype on OS and PFS. However, in comparison to patients after CR, a methylated MGMT promoter cannot compensate the disadvantage due to residual tumor volume. In terms of personalized medicine and quality of life as major goal in oncology, neuro-oncologists have to thoroughly discuss advantages and disadvantages of residual tumor volume versus possible neurological deficits in CR.

The advanced development of Cx43 and GAP-43 mediated intercellular networking in IDH1 wildtype diffuse and anaplastic gliomas with lower mitotic rate

PURPOSE

The biologic behavior and the therapeutic resistance of diffuse and anaplastic gliomas varies greatly. This may be explained by differences in cell-to-cell communication, determined by the Cx43-associated junctional activity and the microtubules-defined network, in which GAP-43 is the dominant structural component. We assessed the expression of these crucial communication proteins in samples of patients harboring WHO°II and III gliomas, graded according to the current 4th revised WHO classification.

METHODS

Tissue of adult patients with WHO°II and III gliomas, who underwent surgery between 2014 and 2018, were selected from our institutional biobank. GAP-43 and Cx43 expression was analyzed using IHC. Routine clinical and neuropathological findings were additionally retrieved from our institutional prospective database.

RESULTS

43 (57%) males and 33 (43%) females with a median age of 47 (IqR: 35-61) years were selected. IDH1 wildtype tumors showed a significantly higher expression of Cx43 (p = 0.014) and a tendency for increased GAP-43 production. Advanced Cx43 expression significantly correlated with lower mitosis rate (p = 0.014): more in IDH1 wildtype (r = - 0.57, p = 0.003) than in mutated gliomas (r = - 0.37, p = 0.019). There was no difference in Cx43 or GAP-43 expression in relation to anaplastic phenotype, Gadolinum-contrasted enhancement (CE) on MRI and advanced EGFR or p53 expression.

CONCLUSIONS

Intercellular communication tends to be more relevant in slower proliferating, e.g. lower malignant tumors. They could have more time to establish this network, providing longitudinally acquired resistance against specific oncological therapy. This feature matches the unfavorable IDH1 wildtype status of glioma and supports the noted malignant behavior of these tumors in the upcoming 5th WHO classification of gliomas.

Physiological MRI of microvascular architecture, neovascularization activity, and oxygen metabolism facilitate early recurrence detection in patients with IDH-mutant WHO grade 3 glioma

PURPOSE

This study aimed to determine the diagnostic performance of physiological MRI biomarkers including microvascular perfusion and architecture, neovascularization activity, tissue oxygen metabolism, and tension for recurrence detection of IDH-mutant WHO grade 3 glioma.

METHODS

Sixty patients with IDH-mutant WHO grade 3 glioma who received overall 288 follow-up MRI examinations at 3 Tesla after standard treatment were retrospectively evaluated. A conventional MRI protocol was extended with a physiological MRI approach including vascular architecture mapping and quantitative blood-oxygen-level-dependent imaging which required 7 min extra data acquisition time. Custom-made MATLAB software was used for the calculation of MRI biomarker maps of microvascular perfusion and architecture, neovascularization activity, tissue oxygen metabolism, and tension. Statistical procedures included receiver operating characteristic analysis.

RESULTS

Overall, 34 patients showed recurrence of the WHO grade 3 glioma; of these, in 15 patients, recurrence was detected one follow-up examination (averaged 160 days) earlier by physiological MRI data than by conventional MRI. During this time period, the tumor volume increased significantly (P = 0.001) on average 7.4-fold from 1.5 to 11.1 cm³. Quantitative analysis of MRI biomarkers demonstrated microvascular but no macrovascular hyperperfusion in early recurrence. Neovascularization activity (AUC = 0.833), microvascular perfusion (0.682), and oxygen metabolism (0.661) showed higher diagnostic performance for early recurrence detection of WHO grade 3 glioma compared to conventional MRI including cerebral blood volume (0.649).

CONCLUSION

This study demonstrated that the targeted assessment of microvascular features and tissue oxygen tension as an early sign of neovascularization activity provided valuable information for recurrence diagnostic of WHO grade 3 glioma.

Ventricle contact may be associated with higher 11C methionine PET uptake in glioblastoma

Purpose

Ventricle contact is associated with a worse prognosis and more aggressive tumor characteristics in glioblastoma (GBM). This is hypothesized to be a result of neural stem cells located around the lateral ventricles, in the subventricular zone. 11C Methionine positron emission tomography (metPET) is an indicator for increased proliferation, as it shows uptake of methionine, an amino acid needed for protein synthesis. This study is the first to study metPET characteristics of GBM in relation to ventricle contact.

Methods

A total of 12 patients with IDH wild-type GBM were included. Using MRI, the following regions were determined: primary tumor (defined as contrast enhancing lesion on T1) and peritumoral edema (defined as edema visible on FLAIR excluding the enhancement). PET parameters in these areas were extracted using PET fused with MRI imaging. Parameters extracted from the PET included maximum and mean tumor-to-normal ratio (TNRmax and TNRmean) and metabolic tumor volume (MTV).

Results

TNRmean of the primary tumor showed significantly higher values for the ventricle-contacting group compared to that for the non-contacting group (4.44 vs 2.67, p = 0.030). Other metPET parameters suggested higher values for the ventricle-contacting group, but these differences did not reach statistical significance.

Conclusion

GBM with ventricle contact demonstrated a higher methionine uptake and might thus have increased proliferation compared with GBM without ventricle contact. This might explain survival differences and should be considered in treatment decisions.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00234-021-02742-7.

Blood-Based Biomarkers for Glioma in the Context of Gliomagenesis: A Systematic Review

BACKGROUND

Gliomas are the most common and aggressive tumors of the central nervous system. A robust and widely used blood-based biomarker for glioma has not yet been identified. In recent years, a plethora of new research on blood-based biomarkers for glial tumors has been published. In this review, we question which molecules, including proteins, nucleic acids, circulating cells, and metabolomics, are most promising blood-based biomarkers for glioma diagnosis, prognosis, monitoring and other purposes, and align them to the seminal processes of cancer.

METHODS

The Pubmed and Embase databases were systematically searched. Biomarkers were categorized in the identified biomolecules and biosources. Biomarker characteristics were assessed using the area under the curve (AUC), accuracy, sensitivity and/or specificity values and the degree of statistical significance among the assessed clinical groups was reported.

RESULTS

7,919 references were identified: 3,596 in PubMed and 4,323 in Embase. Following screening of titles, abstracts and availability of full-text, 262 articles were included in the final systematic review. Panels of multiple biomarkers together consistently reached AUCs >0.8 and accuracies >80% for various purposes but especially for diagnostics. The accuracy of single biomarkers, consisting of only one measurement, was far more variable, but single microRNAs and proteins are generally more promising as compared to other biomarker types.

CONCLUSION

Panels of microRNAs and proteins are most promising biomarkers, while single biomarkers such as GFAP, IL-10 and individual miRNAs also hold promise. It is possible that panels are more accurate once these are involved in different, complementary cancer-related molecular pathways, because not all pathways may be dysregulated in cancer patients. As biomarkers seem to be increasingly dysregulated in patients with short survival, higher tumor grades and more pathological tumor types, it can be hypothesized that more pathways are dysregulated as the degree of malignancy of the glial tumor increases. Despite, none of the biomarkers found in the literature search seem to be currently ready for clinical implementation, and most of the studies report only preliminary application of the identified biomarkers. Hence, large-scale validation of currently identified and potential novel biomarkers to show clinical utility is warranted.

Large Adult Spinal Diffuse Midline Histone H3 Lysine27-to-Methionine-Mutant Glioma With Intramedullary and Extramedullary Components Presenting With Progressive Hydrocephalus: A Case Report Highlighting Unique Imaging Findings and Treatment

Diffuse midline glioma with histone H3 lysine27-to-methionine mutation (H3 K27M mutation) is a rare, aggressive tumor that is designated as World Health Organization (WHO) grade IV regardless of histologic features. Preoperative diagnosis remains challenging due to limited evidence regarding distinctive clinical and imaging characteristics. We describe the case of a young woman who presented with progressively worsening headaches due to communicating hydrocephalus. MR imaging with contrast of the cervical and thoracic spine revealed diffuse leptomeningeal enhancement with focal areas of intramedullary and subarachnoid T2 hyperintensity and enhancement, suggestive of a potential infectious process. Intraoperatively, no epidural pathology was identified, and with the differential diagnosis remaining broad, a second procedure was conducted involving intradural exploration and biopsy of a lesion. This was then identified as a diffuse midline glioma with H3 K27M mutation. The nonfocal clinical presentation in the setting of communicating hydrocephalus as well as the significant exophytic tumor growth and imaging findings made the initial diagnosis unique and challenging. This case, therefore, emphasizes the rare presentation of this tumor, and the need for further understanding of the clinical and imaging characteristics of this disease as well as the need for effective therapeutics.

Accuracy of Machine Learning Algorithms for the Classification of Molecular Features of Gliomas on MRI: A Systematic Literature Review and Meta-Analysis

Simple Summary

Glioma prognosis and treatment are based on histopathological characteristics and molecular profile. Following the World Health Organization (WHO) guidelines (2016), the most important molecular diagnostic markers include IDH1/2-genotype and 1p/19q codeletion status, although more recent publications also include ARTX genotype and TERT- and MGMT promoter methylation. Machine learning algorithms (MLAs), however, were described to successfully determine these molecular characteristics non-invasively by using magnetic resonance imaging (MRI) data. The aim of this review and meta-analysis was to define the diagnostic accuracy of MLAs with regard to these different molecular markers. We found high accuracies of MLAs to predict each individual molecular marker, with IDH1/2-genotype being the most investigated and the most accurate. Radiogenomics could therefore be a promising tool for discriminating genetically determined gliomas in a non-invasive fashion. Although encouraging results are presented here, large-scale, prospective trials with external validation groups are warranted.

Abstract

Treatment planning and prognosis in glioma treatment are based on the classification into low- and high-grade oligodendroglioma or astrocytoma, which is mainly based on molecular characteristics (IDH1/2- and 1p/19q codeletion status). It would be of great value if this classification could be made reliably before surgery, without biopsy. Machine learning algorithms (MLAs) could play a role in achieving this by enabling glioma characterization on magnetic resonance imaging (MRI) data without invasive tissue sampling. The aim of this study is to provide a performance evaluation and meta-analysis of various MLAs for glioma characterization. Systematic literature search and meta-analysis were performed on the aggregated data, after which subgroup analyses for several target conditions were conducted. This study is registered with PROSPERO, CRD42020191033. We identified 724 studies; 60 and 17 studies were eligible to be included in the systematic review and meta-analysis, respectively. Meta-analysis showed excellent accuracy for all subgroups, with the classification of 1p/19q codeletion status scoring significantly poorer than other subgroups (AUC: 0.748, p = 0.132). There was considerable heterogeneity among some of the included studies. Although promising results were found with regard to the ability of MLA-tools to be used for the non-invasive classification of gliomas, large-scale, prospective trials with external validation are warranted in the future.

Radiological assessment schedule for 1p/19q-codeleted gliomas during the surveillance period using parametric modeling

Background

There have been no evidence-based guidelines on the optimal schedule for the radiological assessment of 1p/19q-codeleted glioma. This study aimed to recommend an appropriate radiological evaluation schedule for 1p/19q-codeleted glioma during the surveillance period through parametric modeling of the progression-free survival (PFS) curve.

Methods

A total of 234 patients with 1p/19q-codeleted glioma (137 grade II and 97 grade III) who completed regular treatment were retrospectively reviewed. The patients were stratified into each layered progression risk group by recursive partitioning analysis. A piecewise exponential model was used to standardize the PFS curves. The cutoff value of the progression rate among the remaining progression-free patients was set to 10% at each scan.

Results

Progression risk stratification resulted in 3 groups. The optimal magnetic resonance imaging (MRI) interval for patients without a residual tumor was every 91.2 weeks until 720 weeks after the end of regular treatment following the latent period for 15 weeks. For patients with a residual tumor after the completion of adjuvant radiotherapy followed by chemotherapy, the optimal MRI interval was every 37.5 weeks until week 90 and every 132.8 weeks until week 361, while it was every 33.6 weeks until week 210 and every 14.4 weeks until week 495 for patients with a residual tumor after surgery only or surgery followed by radiotherapy only.

Conclusions

The optimal radiological follow-up schedule for each progression risk stratification of 1p/19q-codeleted glioma can be established from the parametric modeling of PFS.

From Laboratory Studies to Clinical Trials: Temozolomide Use in IDH-Mutant Gliomas

In this review, we discuss the use of the alkylating agent temozolomide (TMZ) in the treatment of IDH-mutant gliomas. We describe the challenges associated with TMZ in clinical (drug resistance and tumor recurrence) and preclinical settings (variabilities associated with in vitro models) in treating IDH-mutant glioma. Lastly, we summarize the emerging therapeutic targets that can potentially be used in combination with TMZ.

Chimeric Antigen Receptor T Cells for Glioblastoma: Current Concepts, Challenges, and Future Perspectives

Glioblastoma is the most common malignant primary brain tumor and is associated with a poor prognosis even after multimodal therapy. Chimeric antigen receptor (CAR) T cells have emerged as a promising therapeutic avenue in glioblastoma. CARs incorporate antigen-recognition moieties that endow autologous T cells with specificity against antigens expressed on glioblastoma (e.g., interleukin [IL]-13Rα2, epidermal growth factor receptor variant III [EGFRvIII], and human epidermal growth factor receptor 2 [HER2]). Compelling antitumor effects of such therapy have been shown in murine glioblastoma models. In humans, 5 phase I/II studies on IL-13Rα2-, EGFRvIII-, and HER2-directed CAR T cells for the treatment of glioblastoma have been published suggesting an acceptable safety profile. However, antitumor effects fell short of expectations in these initial clinical studies. Tumor heterogeneity, antigen loss, and the immunosuppressive tumor microenvironment are among the most important factors to limit the efficacy of CAR T-cell therapy in glioblastoma. Novel target antigens, modification of CAR T-cell design, the combination of CAR T-cell therapy with other therapeutic approaches, but also the use of CAR natural killer cells or CAR macrophages may optimize antitumor effects. Numerous clinical trials studying such approaches are ongoing, as well as several preclinical studies. With an increasing understanding of immune-escape mechanisms of glioblastoma and novel manufacturing techniques for CARs, CAR T cells may provide clinically relevant activity in glioblastoma. This review focuses on the use of CAR T cells in glioblastoma, but also introduces the basic structure, mechanisms of action, and relevant side effects of CAR T cells.

Update on neuroimaging in brain tumours

PURPOSE OF REVIEW

To highlight some of the recent advances in magnetic resonance imaging (MRI), in terms of acquisition, analysis, and interpretation for primary diagnosis, treatment planning, and surveillance of patients with a brain tumour.

RECENT FINDINGS

The rapidly emerging field of radiomics associates large numbers of imaging features with clinical characteristics. In the context of glioma, attempts are made to correlate such imaging features with the tumour genotype, using so-called radiogenomics. The T2-fluid attenuated inversion recovery (FLAIR) mismatch sign is an easy to apply imaging feature for identifying isocitrate dehydrogenase-mutant 1p/19q intact glioma with very high specificity.For treatment planning, resting state functional MRI (fMRI) may become as powerful as task-based fMRI. Functional ultrasound has shown the potential to identify functionally active cortex during surgery.For tumour response assessment automated techniques have been developed. Multiple new guidelines have become available, including those for adult and paediatric glioma and for leptomeningeal metastases, as well as on brain metastasis and perfusion imaging.

SUMMARY

Neuroimaging plays a central role but still often falls short on essential questions. Advanced imaging acquisition and analysis techniques hold great promise for answering such questions, and are expected to change the role of neuroimaging for patient management substantially in the near future.

PCV chemotherapy alone for WHO grade 2 oligodendroglioma: prolonged disease control with low risk of malignant progression

Introduction

The role of chemotherapy alone in newly diagnosed WHO grade 2 oligodendroglioma after biopsy, incomplete or gross total resection remains controversial. We here analyze the clinical outcome of four patient cohorts being treated with either procarbazine, CCNU and vincristine (PCV) or temozolomide (TMZ) after biopsy, resection only, or wait-and-scan after biopsy.

Methods

Patients (n = 142) with molecularly defined oligodendroglioma (WHO 2016) were assigned to four cohorts: W&S, wait-and-scan after stereotactic biopsy (n = 59); RES, surgical resection only (n = 27); TMZ, temozolomide after biopsy (n = 26) or PCV (n = 30) after biopsy. Presurgical MRI T2 tumor volumes were obtained by manual segmentation. Progression-free survival (PFS), post-recurrence PFS (PR-PFS) and rate of histological progression to grade 3 were analyzed.

Results

PFS was longest after PCV (9.1 years), compared to 5.1 years after W&S, 4.4 years after RES and 3.6 years after TMZ. The rate of histological progression from grade 2 to 3 within 10 years was 9% for the PCV, 29% for the W&S, 67% for the RES and 75% for the TMZ group (p = 0.01). In the W&S group, patients treated with PCV at first relapse had a longer PFS from intervention than those treated with TMZ (7.2 vs 4.0 years, p = 0.04). Multivariate analysis identified smaller tumor volume prior to any intervention (p = 0.02) to be prognostic for PFS.

Conclusions

PCV chemotherapy alone is an effective treatment for WHO grade 2 oligodendroglioma, with long PFS and low rate of histological progression.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11060-021-03765-z.

An Update on Glioblastoma Biology, Genetics, and Current Therapies: Novel Inhibitors of the G Protein-Coupled Receptor CCR5

The mechanisms governing therapeutic resistance of the most aggressive and lethal primary brain tumor in adults, glioblastoma, have increasingly focused on tumor stem cells. These cells, protected by the periarteriolar hypoxic GSC niche, contribute to the poor efficacy of standard of care treatment of glioblastoma. Integrated proteogenomic and metabolomic analyses of glioblastoma tissues and single cells have revealed insights into the complex heterogeneity of glioblastoma and stromal cells, comprising its tumor microenvironment (TME). An additional factor, which isdriving poor therapy response is the distinct genetic drivers in each patient's tumor, providing the rationale for a more individualized or personalized approach to treatment. We recently reported that the G protein-coupled receptor CCR5, which contributes to stem cell expansion in other cancers, is overexpressed in glioblastoma cells. Overexpression of the CCR5 ligand CCL5 (RANTES) in glioblastoma completes a potential autocrine activation loop to promote tumor proliferation and invasion. CCL5 was not expressed in glioblastoma stem cells, suggesting a need for paracrine activation of CCR5 signaling by the stromal cells. TME-associated immune cells, such as resident microglia, infiltrating macrophages, T cells, and mesenchymal stem cells, possibly release CCR5 ligands, providing heterologous signaling between stromal and glioblastoma stem cells. Herein, we review current therapies for glioblastoma, the role of CCR5 in other cancers, and the potential role for CCR5 inhibitors in the treatment of glioblastoma.