Diffusely infiltrating astrocytomas: pathology, molecular mechanisms and markers

Development of Predicting Nomograms for Diffuse Astrocytoma and Anaplastic Astrocytoma: A Study Based on the Surveillance, Epidemiology, and End Results Database

BACKGROUND

Astrocytoma is a type of adult-type diffuse gliomas that includes diffuse astrocytoma (DA) and anaplastic astrocytoma (AA). However, comprehensive investigations into the risk assessment and prognosis of DA and AA using population-based studies remain noticeably scarce.

METHODS

In this study, we developed 2 predictive nomograms to evaluate the susceptibility and prognosis associated with DA and AA. The study cohort comprised 3837 individuals diagnosed with DA or AA between 2010 and 2019 selected from the Surveillance, Epidemiology, and End Results (SEER) database. Independent predictors were identified and used to construct the nomograms for overall death and cancer-specific death rates. The performance of the models was assessed using C-index, calibration curves, and receiver operating characteristic curve, and the clinical applicability was evaluated using decision curve analysis.

RESULTS

The receiver operating characteristic curves in this study show excellent clinical applicability and predictive power. Notably, the area under the curves of the training and verification queues was higher than 0.80, thereby cementing the models' precision. Additionally, the calibration plots demonstrate that the anticipated mortality rates strikingly match the measured values. This alignment of figures is sustained in the validation cohort. Furthermore, the decision curve analysis corroborates the models' translational potential, reinforcing their relevance within real-world clinical settings.

CONCLUSIONS

The presented nomograms have not only exhibited good predictive performance but also showcased pragmatic clinical utility in prognosticating patient outcomes. Significantly, this will undoubtedly serve as a valuable asset for oncologists, facilitating informed treatment decisions and meticulous follow-up planning.

Motor dysfunction as a primary symptom predicts poor outcome: multicenter study of glioma symptoms

Background and objectives

The objectives of this study were to investigate the prognostic value of primary symptoms and leading symptoms in adult patients with diffuse infiltrating glioma and to provide a clinical perspective for evaluating survival.

Methods

This study included a retrospective cohort from two tertiary university hospitals (n = 604, 2006-2013, Tampere University Hospital and Turku University Hospital) and a prospective cohort (n = 156, 2014-2018, Tampere University Hospital). Preoperative symptoms were divided into primary and leading symptoms. Results were validated with the newer WHO 2021 classification criteria.

Results

The most common primary symptoms were epileptic seizure (30.8% retrospective, 28.2% prospective), cognitive disorder (13.2% retrospective, 16.0% prospective), headache (8.6% retrospective, 12.8% prospective), and motor paresis (7.0% retrospective, 7.1% prospective). Symptoms that predicted better survival were epileptic seizure and visual or other sense-affecting symptom in the retrospective cohort and epileptic seizure and headache in the prospective cohort. Predictors of poor survival were cognitive disorder, motor dysfunction, sensory symptom, tumor hemorrhage, speech disorder and dizziness in the retrospective cohort and cognitive disorder, motor dysfunction, sensory symptom, and dizziness in the prospective cohort. Motor dysfunction served as an independent predictor of survival in a multivariate model (OR = 1.636).

Conclusion

Primary and leading symptoms in diffuse gliomas are associated with prognoses in retrospective and prospective settings. Motor paresis was an independent prognostic factor for poor survival in multivariate analysis for grade 2-4 diffuse gliomas, especially in glioblastomas.

Postoperative prognostic nomogram for adult grade II/III astrocytoma in the Chinese Han population

Background

Prognostic models of glioma have been the focus of many studies. However, most of them are based on Western populations. Additionally, because of the complexity of healthcare data in China, it is important to select a suitable model based on existing clinical data. This study aimed to develop and independently validate a nomogram for predicting the overall survival (OS) with newly diagnosed grade II/III astrocytoma after surgery.

Methods

Data of 472 patients with astrocytoma (grades II-III) were collected from Qilu Hospital as training cohort while data of 250 participants from Linyi People's Hospital were collected as validation cohort. Cox proportional hazards model was used to construct the nomogram and individually predicted 1-, 3-, and 5-year survival probabilities. Calibration ability, and discrimination ability were analyzed in both training and validation cohort.

Results

Overall survival was negatively associated with histopathology, age, subtotal resection, multiple tumors, lower KPS and midline tumors. Internal validation and external validation showed good discrimination (The C-index for 1-, 3-, and 5-year survival were 0.791, 0.748, 0.733 in internal validation and 0.754, 0.735, 0.730 in external validation, respectively). The calibration curves showed good agreement between the predicted and actual 1-, 3-, and 5-year OS rates.

Conclusion

This is the first nomogram study that integrates common clinicopathological factors to provide an individual probabilistic prognosis prediction for Chinese Han patients with astrocytoma (grades II-III). This model can serve as an easy-to-use tool to advise patients and establish optimized surveillance approaches after surgery.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13755-023-00223-0.

Unraveling the signaling mechanism behind astrocytoma and possible therapeutics strategies: A comprehensive review

BACKGROUND

A form of cancer called astrocytoma can develop in the brain or spinal cord and sometimes causes death. A detailed overview of the precise signaling cascade underlying astrocytoma formation has not yet been revealed, although various factors have been investigated. Therefore, our objective was to unravel and summarize our current understanding of molecular genetics and associated signaling pathways with some possible therapeutic strategies for astrocytoma.

RECENT FINDINGS

In general, four different forms of astrocytoma have been identified in individuals, including circumscribed, diffuse, anaplastic, and multiforme glioblastoma, according to a recent literature review. All types of astrocytoma have a direct connection with some oncogenic signaling cascade. Common signaling is MAPK cascade, including Ras-Raf-ERK, up-regulated with activating EGFR/AKT/PTEN/mTOR and PDGFR. Recent breakthrough studies found that BRAF mutations, including KIAA1549: BRAF and BRAF V600E are responsible for astrocytoma progression. Additionally, cancer progression is influenced by mutations in some tumor suppressor genes, such as the Tp53/ATRX and MGMT mutant. As synthetic medications must cross the blood-brain barrier (BBB), modulating signal systems such as miRNA is the primary option for treating patients with astrocytoma. However, available surgery, radiation therapy, and experimental therapies such as adjuvant therapy, anti-angiogenic therapy, and EGFR-targeting antibody drug are the usual treatment for most types of astrocytoma. Similar to conventional anticancer medications, some phytochemicals slow tumor growth by simultaneously controlling several cellular proteins, including those involved in cell cycle regulation, apoptosis, metastatic spread, tyrosine kinase, growth factor receptor, and antioxidant-related proteins.

CONCLUSION

In conclusion, cellular and molecular signaling is directly associated with the development of astrocytoma, and a combination of conventional and alternative therapies can improve the malignancy of cancer patients.

Radiology-Pathology and Surgical Correlation in Astroblastoma

Astroblastoma is a rare astrocytic glial neoplasm that affects mainly young girls, peaking between 10 and 30 years of age, with low- and high-grade manifestations. Imaging characteristics are well-described, but histopathologic and, more recently, molecular analysis is fundamental to establish the diagnosis, now based on MN1 alterations. We describe a case with typical imaging and histologic features of an MN1-altered astroblastoma.

Classification of adult-type diffuse gliomas: Impact of the World Health Organization 2021 update

Over the last decade, developments in molecular profiling have radically altered the diagnosis, classification, and management of numerous cancer types, with primary brain tumors being no exception. Although historically brain tumors have been classified based on their morphological characteristics, recent advances have allowed refinement of tumor classification based on molecular alterations. This shift toward molecular classification of primary brain tumors is reflected in the 2021 5^th edition of the WHO classification of central nervous system tumors (WHO 2021). In this review, we will discuss the most recent updates to the classification of adult‐type diffuse gliomas, a group of highly infiltrative and largely incurable CNS malignancies. It is our hope continued that refinement of molecular criteria will improve diagnosis, prognostication, and eventually treatment of these devastating tumors.

Serum Inflammatory Biomarkers Contribute to the Prognosis Prediction in High-Grade Glioma

Background

To evaluate the prognostic value of serum inflammatory biomarkers and develop a risk stratification model for high-grade glioma (HGG) patients based on clinical, laboratory, radiological, and pathological factors.

Materials and Methods

A retrospective study of 199 patients with HGG was conducted. Patients were divided into a training cohort (n = 120) and a validation cohort (n = 79). The effects of potential associated factors on the overall survival (OS) time were investigated and the benefits of serum inflammatory biomarkers in improving predictive performance was assessed. Univariable and multivariable Cox regression analyses, the least absolute shrinkage and selection operator (LASSO) regression analysis, and support vector machines (SVM) were used to select variables for the final nomogram model.

Results

After multivariable Cox, LASSO, and SVM analysis, in addition to 3 other clinico-pathologic factors, platelet-to-lymphocyte ratio (PLR) >144.4 (hazard ratio [HR], 2.05; 95% confidence interval [CI], 1.25–3.38; P = 0.005) were left for constructing the predictive model. The model with PLR exhibited a better predictive performance than that without them in both cohorts. The nomogram based on the model showed an excellent ability of discrimination in the entire cohort (C-index, 0.747; 95%CI, 0.706–0.788). The calibration curves showed good consistency between the predicted and observed survival probability.

Conclusion

Our study confirmed the prognostic value of serum inflammatory biomarkers including PLR and established a comprehensive scoring system for the OS prediction in HGG patients.

The Diagnostic Value of Conventional MRI and CT Features in the Identification of the IDH1-Mutant and 1p/19q Co-Deletion in WHO Grade II Gliomas

RATIONALE AND OBJECTIVES

The classification of patients based on pathology and molecular features is important for improving WHO grade II glioma patient prognosis, especially for the initially diagnosed patients. Less invasive and more convenient methods for the prediction of the pathological type and gene status are desired.

MATERIALS AND METHODS

This study investigates the ability to use conventional magnetic resonance imaging (MRI) and computed tomography (CT) features for determining the Isocitrate Dehydrogenase (IDH)-mutant and 1p/19q-codeletion status, through a retrospective review of information obtained from 189 WHO grade II glioma patients. Diffuse astrocytoma (IDH-mutant), Diffuse astrocytoma (IDH- wildtype) and Oligodendroglioma (IDH-mutant and 1p/19q co-deletion) were included in this cohort. All patients were divided into IDH-mutant group and IDH-wildtype group according to the IDH R132H mutation status. Moreover, all patients were divided into 1p/19q co-deletion group and 1p/19q non-codeletion group according to the 1p and 19q chromosome status. Patients underwent pre-operative CT and MRI scans, followed by operation and histopathological analyses, including immunohistochemistry and polymerase chain reaction analysis for IDH mutants, and fluorescence capillary electrophoresis analysis for the 1p/19q co-deletion. The χ² test, logistical regression and receiver operating characteristic curve analysis were conducted for statistical analysis.

RESULTS

IDH-mutant group patients exhibited a higher calcification frequency (25.2% vs 2.4%, p = 0.006) and lower frequency of T1 enhancement (20.4% vs 38.1%, p = 0.028) comparing patients in IDH-wildtype group, while 1p/19q co-deletion group patients exhibited a higher calcification frequency (46.67% vs 2.6%, p < 0.001) and lower homogenous signal frequency in T2WI (12.0% vs 31.6%, p = 0.014), sharp lesion margins (14.7% vs 43.0%, p = 0.010), T2/fluid attenuated inversion recovery mismatch signs (22.7% vs 50.9%, p = 0.001), and subventricular zone involvement (64.0% vs 15.8%, p = 0.021) comparing patients in 1p/19q non-codeletion group. According to the results of receiver operating characteristic analysis, these features were observed to have certain diagnostic abilities, especially with regard to combination parameters, which had a high diagnostic capability, with an area under the curve of 0.848.

CONCLUSION

Conventional MRI and CT features, which still represent the most convenient and widely used predictive method, might be a promising noninvasive predictor for differentiating between varied WHO grade II gliomas. Patients with calcification and T1 nonenhancement are more likely to be IDH-mutant. Moreover, patients with noncalcification, homogenous signal, sharp lesion margins, subventricular zone involvement on T2 and T2/fluid attenuated inversion recovery mismatch signs are more likely to be 1p/19q non-codeletion.

The IDH-TAU-EGFR triad defines the neovascular landscape of diffuse gliomas

Gliomas that express the mutated isoforms of isocitrate dehydrogenase 1/2 (IDH1/2) have better prognosis than wild-type (wt) IDH1/2 gliomas. However, how these mutant (mut) proteins affect the tumor microenvironment is still a pending question. Here, we describe that the transcription of microtubule-associated protein TAU (MAPT), a gene that has been classically associated with neurodegenerative diseases, is epigenetically controlled by the balance between wt and mut IDH1/2 in mouse and human gliomas. In IDH1/2 mut tumors, we found high expression of TAU that decreased with tumor progression. Furthermore, MAPT was almost absent from tumors with epidermal growth factor receptor (EGFR) mutations, whereas its trancription negatively correlated with overall survival in gliomas carrying wt or amplified (amp) EGFR We demonstrated that the overexpression of TAU, through the stabilization of microtubules, impaired the mesenchymal/pericyte-like transformation of glioma cells by blocking EGFR, nuclear factor kappa-light-chain-enhancer of activated B (NF-κB) and the transcriptional coactivator with PDZ-binding motif (TAZ). Our data also showed that mut EGFR induced a constitutive activation of this pathway, which was no longer sensitive to TAU. By inhibiting the transdifferentiation capacity of EGFRamp/wt tumor cells, TAU protein inhibited angiogenesis and favored vascular normalization, decreasing glioma aggressiveness and increasing their sensitivity to chemotherapy.

The role of neuropathology in the management of newly diagnosed glioblastoma: a systematic review and evidence-based clinical practice guideline

TARGET POPULATION

These recommendations apply to adult patients with newly diagnosed or suspected glioblastoma (GBM) QUESTION : For adult patients with newly diagnosed GBM does testing for Isocitrate Dehydrogenase 1 or 2 (IDH 1/2) mutations afford benefit beyond standard histopathology in providing accurate classification and outcome prognostication? Level III IDH 1/2 mutational status by immunohistochemistry (IHC) and/or sequencing is suggested for classification and prognostic information. Level III Non-canonical IDH 1/2 mutations are very rare in patients aged 55 or older and universal testing of variant mutations by sequence analysis is not suggested for this age range.

QUESTION

For adult patients with lower grade infiltrating astrocytomas (WHO grades II and III) can the IDH-wildtype status designation supersede histopathology to predict prognosis and biologic relevance to eventual behavior as a GBM? Level III The designation of infiltrating astrocytomas (WHO grades II and III) as IDH-wildtype is not suggested as sufficient for a higher grade designation alone. Level III It is suggested that IDH-wildtype WHO grades II and III astrocytomas be tested for molecular-genetic alterations typical of IDH-wildtype GBM such as EGFR amplification, gain of chromosome 7/loss of chromosome 10 and TERT-p mutation to substantiate prediction of behavior similar to IDH-wildtype glioblastoma. Level III It is suggested that a diagnosis of diffuse astrocytic glioma, IDH-wildtype, with molecular features of GBM, WHO grade IV be rendered for infiltrating astrocytomas that lack histologic criteria of GBM but harbors molecular-genetic alterations of IDH-wildtype glioblastoma.

QUESTION

For adult patients with newly diagnosed infiltrating glioma arising in the midline does testing for H3-K27M mutations provide information beyond that gained by histopathology for accurate classification and outcome prognostication? Level III It is suggested that infiltrating gliomas arising in midline anatomic locations be tested for the H3-K27M mutation as they tend to exhibit WHO grade IV behavior even if they lack histologic criteria for glioblastoma.

Immune Profiling of Gliomas Reveals a Connection with IDH1/2 Mutations, Tau Function and the Vascular Phenotype

Simple Summary

In the present work we have confirmed that gliomas with isocitrate dehydrogenase 1/2 mutations are “cold” tumors, whereas the immune content of their wild-type counterparts is more heterogeneous. A large subgroup of wild-type glioblastomas is characterized by an important immune component, particularly enriched in myeloid cells, and an elevated expression of the ligand of programmed death ligand 1 (PD-L1) in the immune compartment. The rest contain few lymphocytes and myeloid cells. Notably, we have observed a direct correlation between the immune content and the presence of vascular alterations, as well as with the reduced expression of Tau, a microtubule-binding protein that we described as a negative regulator of angiogenesis. Using syngeneic mouse models, we show that overexpression of Tau reduces the immune content, delaying tumor growth.

Abstract

Background: Gliomas remain refractory to all attempted treatments, including those using immune checkpoint inhibitors. The characterization of the tumor (immune) microenvironment has been recognized as an important challenge to explain this lack of response and to improve the therapy of glial tumors. Methods: We designed a prospective analysis of the immune cells of gliomas by flow cytometry. Tumors with or without isocitrate dehydrogenase 1/2 (IDH1/2) mutations were included in the study. The genetic profile and the presence of different molecular and cellular features of the gliomas were analyzed in parallel. The findings were validated in syngeneic mouse models. Results: We observed that few immune cells infiltrate mutant IDH1/2 gliomas whereas the immune content of IDH1/2 wild-type tumors was more heterogeneous. Some of them contained an important immune infiltrate, particularly enriched in myeloid cells with immunosuppressive features, but others were more similar to mutant IDH1/2 gliomas, with few immune cells and a less immunosuppressive profile. Notably, we observed a direct correlation between the percentage of leukocytes and the presence of vascular alterations, which were associated with a reduced expression of Tau, a microtubule-binding protein that controls the formation of tumor vessels in gliomas. Furthermore, overexpression of Tau was able to reduce the immune content in orthotopic allografts of GL261 cells, delaying tumor growth. Conclusions: We have confirmed the reduced infiltration of immune cells in IDH1/2 mutant gliomas. By contrast, in IDH1/2 wild-type gliomas, we have found a direct correlation between the presence of vascular alterations and the entrance of leukocytes into the tumors. Interestingly, high levels of Tau inversely correlated with the vascular and the immune content of gliomas. Altogether, our results could be exploited for the design of more successful clinical trials with immunomodulatory molecules.

Proteomics identifies EGF-like domain multiple 7 as a potential therapeutic target for epidermal growth factor receptor-positive glioma

Background

Glioma, the most frequent primary tumor of the central nervous system, has poor prognosis. The epidermal growth factor receptor (EGFR) pathway and angiogenesis play important roles in glioma growth, invasion, and recurrence. The present study aimed to use proteomic methods to probe into the role of the EGF‐EGFR‐angiogenesis axis in the tumorigenesis of glioma and access the therapeutic efficacy of selumetinib on glioma.

Methods

Proteomic profiling was used to characterize 200 paired EGFR‐positive and EGFR‐negative glioma tissues of all pathological types. The quantitative mass spectrometry data were used for systematic analysis of the proteomic profiles of 10 EGFR‐positive and 10 EGFR‐negative glioma cases. Consensus‐clustering analysis was used to screen target proteins. Immunofluorescence analysis, cell growth assay, and intracranial xenograft experiments were used to verify and test the therapeutic effect of selumetinib on glioma.

Results

Advanced proteomic screening demonstrated that the expression of EGF‐like domain multiple 7 (EGFL7) was higher in EGFR‐positive tumor tissues than in EGFR‐negative tumor tissues. In addition, EGFL7 could act as an activator in vitro and in vivo to promote glioma cell proliferation. EGFL7 was associated strongly with EGFR and prognosis. EGFL7 knockdown effectively suppressed glioma cell proliferation. Selumetinib treatment showed tumor reduction effect in EGFR‐positive glioblastoma xenograft mouse model.

Conclusions

EGFL7 is a potential diagnostic biomarker and therapeutic target of glioma. Selumetinib could target the EGFR pathway and possibly improve the prognosis of EGFR‐positive glioma.

SNHG17 drives malignant behaviors in astrocytoma by targeting miR-876-5p/ERLIN2 axis

Background

Astrocytoma is a common tumor type in primary central nervous system and has a high death rate around the world. Aberrant expression of long non-coding RNAs (lncRNAs) has been introduced by emerging studies to result in the development of diverse cancers.

Methods

RT-qPCR examined the expression of SNHG17, miR-876-5p and ERLIN2, and western blot evaluated ERLIN2 protein level. RNA pull down and luciferase reporter assays illustrated the relationships between SNHG17 and its downstream molecules.

Results

SNHG17 was up-regulated in astrocytoma cells. Moreover, SNHG17 silence could repress the proliferation, migration and invasion of astrocytoma cells. Besides, miR-876-5p was selected out as a downstream molecule of SNHG17 in astrocytoma. ERLIN2 was determined to be targeted by miR-876-5p. ERLIN2 mRNA and protein levels were lessened by miR-876-5p overexpression and SNHG17 silence. Additionally, miR-876-5p overexpression decelerated the biological processes of astrocytoma cells, so did ERLIN2 knockdown. More importantly, the impacts of SNHG17 down-regulation on the malignant behaviors of astrocytoma cells were counteracted by overexpressed ERLIN2 or inhibited miR-876-5p.

Conclusions

SNHG17 could induce the progression of astrocytoma by sponging miR-876-5p to elevate the expression of ERLIN2. This study indicated that SNHG17 has a high potential to be a therapeutic target for astrocytoma.

Correlation between IDH, ATRX, and TERT promoter mutations in glioma

According to the 2016 World Health Organization (WHO) classification of central nervous system tumors, diffuse astrocytic and oligodendroglial tumors are differentiated by the presence of isocitrate dehydrogenase 1 or 2 (IDH1/2) mutation and the combined loss of the short arm of chromosome 1 and the long arm of chromosome 19 (1p/19q co-deletion). IDH-mutant astrocytoma often has p53 and alpha-thalassemia/mental retardation syndrome X-linked (ATRX) mutation, showing the alternative lengthening of telomeres (ALT) phenotype, while IDH-mutant and 1p/19q-co-deleted oligodendroglioma often have wild-type p53 and telomerase reverse transcriptase (TERT) promoter mutation, showing telomerase activation. This study analyzed IDH, ATRX, and TERT promoter mutations, and the correlation between them. Immortalized cells overcome the telomere-related crisis by activating telomerase or ALT. In glioma, telomerase is mainly activated by TERT promoter mutation, while ALT is usually associated with ATRX mutation. Although the mechanism of how ATRX mutation induces ALT remains unclear, ATRX loss alone is believed to be insufficient to induce ALT. Treatments targeting telomere maintenance are promising.

Whole-tumor radiomics analysis of DKI and DTI may improve the prediction of genotypes for astrocytomas: A preliminary study

PURPOSE

To test whether the whole-tumor radiomics analysis of DKI and DTI images could predict IDH and MGMTmet genotypes of astrocytomas.

METHOD

Sixty-two astrocytomas were enrolled. 364 radiomics features of whole tumor were extracted from mean-kurtosis (MK), and mean-diffusivity (MD) images, respectively. The multivariable logistic regression was used to select the most meaningful radiomics features for predicting IDH and MGMTmet genotypes. A radiomics model was built by logistic linear regression. A combined model was established based on selected radiomic, radiological and clinical features. To assess the difference between the models, the Z-test was performed.

RESULTS

The radiomics model built using the three most informative radiomics features for each genotype yielded an AUC of 0.831 ((95 % confidence interval [CI]: 0.721-0.918) for predicting IDH genotype, and 0.835 (95 %CI: 0.686-0.951) for MGMTmet genotype. A combined model for predicting IDH based on the radiomics score, age, and degree of edema reached an AUC of 0.885 (95 %CI: 0.802-0.955) and a combined model for predicting MGMTmet based on radiomics score and edema degree reached an AUC of 0.859 (95 %CI: 0.751-0.945) which was not significantly higher than the radiomics only model (P =  0.081).

CONCLUSIONS

The radiomics models via an objective whole-tumor analysis of MK and MD maps were independent imaging biomarkers for predicting IDH and MGMTmet genotypes, and the combined model further improved the performance for IDH, but not for MGMTmet.

Improving survival prediction of high-grade glioma via machine learning techniques based on MRI radiomic, genetic and clinical risk factors

OBJECTIVES

To develop a radiomic signature to predict overall survival (OS) for high-grade glioma (HGG), and construct a nomogram by combining selected radiomic, genetic and clinical risk factors to further improve the performance of the risk model.

MATERIALS AND METHODS

147 cases of HGG with MRI images, genetic data, clinical data were studied, wherein 112 patients were used as training cohort, and 35 patients were as independent test cohort. Radiomics features were extracted from tumor area and peritumoral edema area on CE-T1WI and T2FLAIR images. Association between radiomics signature, genetic, clinical risk factors and OS was explored by Kaplan-Meier survival analysis and log rank test. The multivariate Cox regression analysis was trained with radiomic features along with selected genetic and clinical risk factors, which was presented as a nomogram.

RESULTS

The radiomic signature constructed by 11 radiomics features stratified patients into low- and high-risk groups, and the C-Index for OS prediction was 0.707 and 0.711 in training and test cohorts, respectively. The multivariable Cox regression analysis identified radiomics signature (hazard ratio (HR): 2.18, P =  0.005), IDH (HR: 0.490, P =  0.007) and age (HR: 1.039, P =  0.005) as independent risk factors. A nomogram combining these independent risk factors further improved the performance for OS estimation (C-index = 0.764 and 0.758 in training and test cohorts, respectively).

CONCLUSION

The radiomics signature is a new prognostic biomarker for HGG. A nomogram incorporating radiomics signature, IDH and age improved the performance of OS estimation, which might be a new complement to the treatment guidelines of glioma.

A radiomics nomogram may improve the prediction of IDH genotype for astrocytoma before surgery

OBJECTIVES

To develop and validate a radiomics nomogram to preoperative prediction of isocitrate dehydrogenase (IDH) genotype for astrocytomas, which might contribute to the pretreatment decision-making and prognosis evaluating.

METHODS

One hundred five astrocytomas (Grades II-IV) with contrast-enhanced T1-weighted imaging (CE-T1WI), T2 fluid-attenuated inversion recovery (T2FLAIR), and apparent diffusion coefficient (ADC) map were enrolled in this study (training cohort: n = 74; validation cohort: n = 31). IDH1/2 genotypes were determined using Sanger sequencing. A total of 3882 radiomics features were extracted. Support vector machine algorithm was used to build the radiomics signature on the training cohort. Incorporating radiomics signature and clinico-radiological risk factors, the radiomics nomogram was developed. Receiver operating characteristic (ROC) curve and area under the curve (AUC) were used to assess these models. Kaplan-Meier survival analysis and log rank test were performed to assess the prognostic value of the radiomics nomogram.

RESULTS

The radiomics signature was built by six selected radiomics features and yielded AUC values of 0.901 and 0.888 in the training and validation cohorts. The radiomics nomogram based on the radiomics signature and age performed better than the clinico-radiological model (training cohort, AUC = 0.913 and 0.817; validation cohort, AUC = 0.900 and 0.804). Additionally, the survival analysis showed that prognostic values of the radiomics nomogram and IDH genotype were similar (log rank test, p < 0.001; C-index = 0.762 and 0.687; z-score test, p = 0.062).

CONCLUSIONS

The radiomics nomogram might be a useful supporting tool for the preoperative prediction of IDH genotype for astrocytoma, which could aid pretreatment decision-making.

KEY POINTS

• The radiomics signature based on multiparametric and multiregional MRI images could predict IDH genotype of Grades II-IV astrocytomas. • The radiomics nomogram performed better than the clinico-radiological model, and it might be an easy-to-use supporting tool for IDH genotype prediction. • The prognostic value of the radiomics nomogram was similar with that of the IDH genotype, which might contribute to prognosis evaluating.

Understanding cognitive functioning in glioma patients: The relevance of IDH-mutation status and functional connectivity

INTRODUCTION

Cognitive deficits occur frequently in diffuse glioma patients, but are limitedly understood. An important marker for survival in these patients is isocitrate dehydrogenase (IDH) mutation (IDH-mut). Patients with IDH-mut glioma have a better prognosis but more often suffer from epilepsy than patients with IDH-wildtype (IDH-wt) glioma, who are generally older and more often have cognitive deficits. We investigated whether global brain functional connectivity differs between patients with IDH-mut and IDH-wt glioma, and whether this measure reflects variations in cognitive functioning in these subpopulations beyond the associated differences in age and presence of epilepsy.

METHODS

We recorded magnetoencephalography and tested cognitive functioning in 54 diffuse glioma patients (31 IDH-mut, 23 IDH-wt). Global functional connectivity between 78 atlas regions spanning the entire cortex was calculated in two frequency bands (theta and alpha). Group differences in global functional connectivity were tested, as was their association with cognitive functioning, controlling for age, education, and presence of epilepsy.

RESULTS

Patients with IDH-wt glioma had lower functional connectivity in the alpha band than patients with IDH-mut glioma (p = 0.040, corrected for age and presence of epilepsy). Lower alpha band functional connectivity was associated with poorer cognitive performance (p < 0.034), corrected for age, education, and presence of epilepsy.

CONCLUSION

Global functional connectivity is lower in patients with IDH-wt diffuse glioma compared to patients with IDH-mut diffuse glioma. Moreover, having lower functional alpha connectivity relates to poorer cognitive performance in patients with diffuse glioma, regardless of age, education, and presence of epilepsy.

Comparing the value of DKI and DTI in detecting isocitrate dehydrogenase genotype of astrocytomas

AIM

To compare the value of diffusion kurtosis imaging (DKI) and diffusion tensor imaging (DTI) in evaluating astrocytomas with an isocitrate dehydrogenase (IDH) genotype.

MATERIALS AND METHODS

Fifty-eight astrocytomas were divided into IDH-wild-type (IDH-W) and IDH-mutant (IDH-M) groups, in all astrocytomas, low-grade astrocytomas (LGA) and high-grade astrocytomas (HGA), respectively. The DKI (mean kurtosis [MK], radial kurtosis [Kr], axial kurtosis [Ka]), and DTI (fractional anisotropy [FA], mean diffusivity [MD]) values were measured. The differences of parameter values between the IDH-W and IDH-M groups were compared by t-test. Receiver operating characteristic (ROC) curves were used to identify the best parameter and z-score tests were used to compare the performance between DKI and DTI.

RESULTS

In all astrocytomas, MK, Ka, and Kr values were significantly higher (p<0.001, p=0.002, and p<0.001), and the MD value (p=0.005) was lower in the IDH-W group than those in the IDH-M group. The areas under the ROC curve (AUC) of MK (0.811) and Kr (0.800) were significantly higher than that of MD (0.704). In LGA, MK, Ka, and Kr values were also significantly higher in the IDH-W group than those in the IDH-M group (p=0.002, p=0.008, p=0.006), whereas MD and FA values showed no differences. In HGA, MK and Kr values were significantly higher (p=0.008, p=0.003), and the MD value (p=0.031) was significantly lower in the IDH-W group than that in the IDH-M group, the AUC of MK (0.750) and Kr (0.788) were also higher than MD (0.637; p=0.032, p=0.025).

CONCLUSION

DKI may be a new imaging biomarker for evaluating the IDH genotype of astrocytomas, which is more accurate and stable than DTI.

Metabolic reprogramming in the pathogenesis of glioma: Update

Cancer is a genetic disease that is currently classified not only by its tissue and cell type of origin but increasingly by its molecular composition. Increasingly, tumor classification and subtyping is being performed based upon the oncogene gains, tumor suppressor losses, and associated epigenetic and transcriptional features. However, cancers, including brain tumors, are also characterized by profound alterations in cellular metabolism. At present, even though signature mutations in known metabolic enzymes are recognized as being important, the metabolic landscape of tumors is not currently incorporated into tumor diagnostic categories. Here we describe a set of recent discoveries on metabolic reprogramming driven by mutations in the genes for the isocitrate dehydrogenase (IDH) and receptor tyrosine kinase (RTK) pathways, which are the most commonly observed aberrations in diffuse gliomas. We highlight the importance of oncometabolites to dynamically shift the epigenetic landscape in IDH-mutant gliomas, and c-Myc and mechanistic target of rapamycin (mTOR) complexes in RTK-mutated gliomas to adapt to the microenvironment through metabolic reprogramming. These signify the integration of the genetic mutations with metabolic reprogramming and epigenetic shifts in diffuse gliomas, shedding new light onto potential patient subsets, coupled with information to guide the development of new therapeutic opportunities against the deadly types of brain tumors.

Loss of BCAT1 Expression is a Sensitive Marker for IDH-Mutant Diffuse Glioma

BACKGROUND

IDH mutation is an important prognostic factor of diffuse astrocytomas. Although the majority of IDH mutations could be identified by immunohistochemical (IHC) stain for R132H-mutant IDH1, DNA sequencing would be required for IHC negative cases to determine their IDH mutation status. This approach is not cost-effective for tumors with low IDH mutation rates.

OBJECTIVE

To investigate whether BCAT1 could be used as a surrogate marker for IDH mutations, because BCAT1 is an enzyme related to IDH genes.

METHODS

A group of 120 anaplastic astrocytomas were immunostained for BCAT1, ATRX, and R132H-mutant IDH1. Staining results correlated with the results of DNA sequencing of IDH1/IDH2.

RESULTS

DNA sequencing showed IDH1/2 mutations in 50.8% of cases of which 73.8% had IDH1 R132H mutation. Several IDH1 noncodon 132 mutations, ie, G97D, S122N, G123E, I130K, and G131S, which had uncertain prognostic significance, were identified. IHC stain for R132H-mutant IDH1 identified 93.3% of IDH1 R132H mutations and 70.5% of all IDH mutations. BCAT1 loss was seen in 65.8% of cases, its sensitivity to identify IDH mutations was 96.7%. The sensitivity reached 100% for IDH1 codon 132 and IDH2 codon 172 mutations.

CONCLUSION

Positive BCAT1 stain could be used to exclude diffuse gliomas with IDH1 codon 132 and IDH2 codon 172 mutations. Selecting cases with negative BCAT1 and R132H-mutant IDH1 staining for DNA sequencing of IDH1/2 genes could improve the cost-effectiveness of detecting IDH mutations particularly in tumors with low IDH mutation rates, and confine the need of 1p/19q assay in IDH-mutant tumors.

Effect of marital status on survival in glioblastoma multiforme by demographics, education, economic factors, and insurance status

The relationship between marital status and glioblastoma multiforme (GBM) has not been addressed in depth. Here, we aimed to investigate the association between marital status and survival in GBM. We searched the Surveillance, Epidemiology, and End Results (SEER) database and extracted the data of eligible patients diagnosed with GBM after 2004. Marital status was classified as married, divorced/separated, widowed, and single. A Kaplan-Meier test was conducted to compare the survival curves of different groups. Multivariate Cox regression was performed to evaluate overall survival (OS) and cause-specific survival (CSS) in different groups. Subgroup analysis was applied according to demographics, typical education and income levels in the locale, and insurance status. A total of 30 767 eligible patients were included. The median OS values were 9, 7, 3, 9 months in married, divorced/separated, widowed, and single patients, respectively. After adjustment for other covariates, married patients had better OS and CSS than other patients had. In addition to marital status, demographic factors, disease progression factors, local educational level, and insurance status were also associated with survival in GBM. Furthermore, subgroup analyses revealed the protective effect of marriage in most of the comparisons. Notably, the protective effect of marriage becomes more and more apparent as time goes on. The advantageous effect of marriage on GBM survival is especially prominent in patients who are male, older than 60 years of age, White, or living in middle-income counties. In conclusion, marital status is an independent prognostic factor for GBM.

Mitochondria Transcription Factor A: A Putative Target for the Effect of Melatonin on U87MG Malignant Glioma Cell Line

The disruption of mitochondrial activity has been associated with cancer development because it contributes to regulating apoptosis and is the main source of reactive oxygen species (ROS) production. Mitochondrial transcription factor A (TFAM) is a protein that maintains mitochondrial DNA (mtDNA) integrity, and alterations in its expression are associated with mitochondrial damage and cancer development. In addition, studies have shown that mitochondria are a known target of melatonin, the pineal gland hormone that plays an important anti-tumorigenic role. Thus, we hypothesized that melatonin decreases the expression of TFAM (RNA and protein) in the human glioblastoma cell line U87MG, which disrupts mtDNA expression and results in cell death due to increased ROS production and mitochondrial damage. Our results confirm the hypothesis, and also show that melatonin reduced the expression of other mitochondrial transcription factors mRNA (TFB1M and TFB2M) and interfered with mtDNA transcription. Moreover, melatonin delayed cell cycle progression and potentiated the reduction of cell survival due to treatment with the chemotherapeutic agent temozolomide. In conclusion, elucidating the effect of melatonin on TFAM expression should help to understand the signaling pathways involved in glioblastoma progression, and melatonin could be potentially applied in the treatment of this type of brain tumor.

Incorporating Advances in Molecular Pathology Into Brain Tumor Diagnostics

Recent advances in molecular pathology have reshaped the practice of brain tumor diagnostics. The classification of gliomas has been restructured with the discovery of isocitrate dehydrogenase (IDH) 1/2 mutations in the vast majority of lower grade infiltrating gliomas and secondary glioblastomas (GBM), with IDH-mutant astrocytomas further characterized by TP53 and ATRX mutations. Whole-arm 1p/19q codeletion in conjunction with IDH mutations now define oligodendrogliomas, which are also enriched for CIC, FUBP1, PI3K, NOTCH1, and TERT-p mutations. IDH-wild-type (wt) infiltrating astrocytomas are mostly primary GBMs and are characterized by EGFR, PTEN, TP53, NF1, RB1, PDGFRA, and CDKN2A/B alterations, TERT-p mutations, and characteristic copy number alterations including gains of chromosome 7 and losses of 10. Other clinically and genetically distinct infiltrating astrocytomas include the aggressive H3K27M-mutant midline gliomas, and smaller subsets that occur in the setting of NF1 or have BRAF V600E mutations. Low-grade pediatric gliomas are both genetically and biologically distinct from their adult counterparts and often harbor a single driver event often involving BRAF, FGFR1, or MYB/MYBL1 genes. Large scale genomic and epigenomic analyses have identified distinct subgroups of ependymomas tightly linked to tumor location and clinical behavior. The diagnosis of embryonal neoplasms also integrates molecular testing: (I) 4 molecularly defined, biologically distinct subtypes of medulloblastomas are now recognized; (II) 3 histologic entities have now been reclassified under a diagnosis of "embryonal tumor with multilayered rosettes (ETMR), C19MC-altered"; and (III) atypical teratoid/rhabdoid tumors (AT/RT) now require SMARCB1 (INI1) or SMARCA4 (BRG1) alterations for their diagnosis. We discuss the practical use of contemporary biomarkers for an integrative diagnosis of central nervous system neoplasia.

Association between mutant IDHs and tumorigenesis in gliomas

To become immortalized, cells need to maintain the telomere length via the activation of telomerase or alternative lengthening of telomere. Mutations in IDH1/2 are strongly associated with the early stage of gliomagenesis. Previous work has shown that the accumulation of 2-HG, which is induced by mutant IDH1/2, inhibits α-KG-dependent deoxygenase and leads to genome-wide histone and DNA methylation alterations. These alterations are believed to contribute to tumorigenesis. H-Ras can transform human astrocytes with the inactivation of p53/pRb and expression of hTERT; however, mutant IDH1 can also transform cells. Moreover, mutant IDH1 can drive the immortalization and transformation of p53-/pRb-deficient astrocytes by reactivating telomerase and stabilizing telomeres in combination with increased histone lysine methylation and c-Myc/Max binding at the TERT promoter. It remains unclear whether mutant IDH1/2 acts only as the initial driver of gliomagenesis or it maintains transformed cells. Clinical studies are being performed to assess the use of mutant IDH1/2 inhibitors for treating gliomas.

Glioma: experimental models and reality

In theory, in vitro and in vivo models for human gliomas have great potential to not only enhance our understanding of glioma biology, but also to facilitate the development of novel treatment strategies for these tumors. For reliable prediction and validation of the effects of different therapeutic modalities, however, glioma models need to comply with specific and more strict demands than other models of cancer, and these demands are directly related to the combination of genetic aberrations and the specific brain micro-environment gliomas grow in. This review starts with a brief introduction on the pathological and molecular characteristics of gliomas, followed by an overview of the models that have been used in the last decades in glioma research. Next, we will discuss how these models may play a role in better understanding glioma development and especially in how they can aid in the design and optimization of novel therapies. The strengths and weaknesses of the different models will be discussed in light of genotypic, phenotypic and metabolic characteristics of human gliomas. The last part of this review provides some examples of how therapy experiments using glioma models can lead to deceptive results when such characteristics are not properly taken into account.

Prognostic value of survivin and DNA topoisomerase IIα in diffuse and anaplastic astrocytomas

Distinguishing WHO grade II astrocytomas from grade III is a difficult task. This study looks into the potential prognostic use of mitotic activity and the proliferation markers Ki67/MiB-1 (Ki67), survivin and DNA topoisomerase IIα (TIIα) in 59 WHO grade II diffuse astrocytomas (DA) and 33 WHO grade III anaplastic astrocytomas (AA), IDH1 R132H-mutated and not otherwise specified (NOS) by means of immunohistochemistry. All proliferation markers showed higher expression in AA compared with DA. Only Ki67 had significantly greater expression in astrocytomas, NOS vs. astrocytomas, IDH1-mutated. Uni-/multivariable COX-regression analyses showed that greater expression of both survivin and TIIα were associated with poorer survival when stratified for IDH1-mutation status and, additionally, achieved hazard rates surpassing clinically established prognostic factors such as age and WHO performance status. Ki67 achieved only statistical significance in univariable analyses, whereas mitoses did not reveal any relation to survival. IDH1-mutated astrocytomas had significantly better survival than astrocytomas, NOS. Among IDH1-mutated astrocytomas no significant difference in survival was shown between DA and AA. Our findings suggest a potential usefulness of proliferation markers in the prognostic setting of astrocytomas independent of IDH1-mutation status, and survivin and TIIα are potential candidates in that regard.

Histologic classification of gliomas

Gliomas form a heterogeneous group of tumors of the central nervous system (CNS) and are traditionally classified based on histologic type and malignancy grade. Most gliomas, the diffuse gliomas, show extensive infiltration in the CNS parenchyma. Diffuse gliomas can be further typed as astrocytic, oligodendroglial, or rare mixed oligodendroglial-astrocytic of World Health Organization (WHO) grade II (low grade), III (anaplastic), or IV (glioblastoma). Other gliomas generally have a more circumscribed growth pattern, with pilocytic astrocytomas (WHO grade I) and ependymal tumors (WHO grade I, II, or III) as the most frequent representatives. This chapter provides an overview of the histology of all glial neoplasms listed in the WHO 2016 classification, including the less frequent "nondiffuse" gliomas and mixed neuronal-glial tumors. For multiple decades the histologic diagnosis of these tumors formed a useful basis for assessment of prognosis and therapeutic management. However, it is now fully clear that information on the molecular underpinnings often allows for a more robust classification of (glial) neoplasms. Indeed, in the WHO 2016 classification, histologic and molecular findings are integrated in the definition of several gliomas. As such, this chapter and Chapter 6 are highly interrelated and neither should be considered in isolation.

Immunotherapy of Malignant Tumors in the Brain: How Different from Other Sites?

Immunotherapy is now advancing at remarkable pace for tumors located in various tissues, including the brain. Strategies launched decades ago, such as tumor antigen-specific therapeutic vaccines and adoptive transfer of tumor-infiltrating lymphocytes are being complemented by molecular engineering approaches allowing the development of tumor-specific TCR transgenic and chimeric antigen receptor T cells. In addition, the spectacular results obtained in the last years with immune checkpoint inhibitors are transfiguring immunotherapy, these agents being used both as single molecules, but also in combination with other immunotherapeutic modalities. Implementation of these various strategies is ongoing for more and more malignancies, including tumors located in the brain, raising the question of the immunological particularities of this site. This may necessitate cautious selection of tumor antigens, minimizing the immunosuppressive environment and promoting efficient T cell trafficking to the tumor. Once these aspects are taken into account, we might efficiently design immunotherapy for patients suffering from tumors located in the brain, with beneficial clinical outcome.

Gliomatosis cerebri: A consensus summary report from the First International Gliomatosis cerebri Group Meeting, March 26-27, 2015, Paris, France

Gliomatosis cerebri (GC) is a universally fatal extensive and diffuse infiltration of brain parenchyma by a glial tumor. Many aspects of this phenomenon remain unknown. The First International Gliomatosis cerebri Group Meeting had the following goals: refine the clinical and radiologic diagnostic criteria for GC, suggest appropriate diagnostic procedures, standardize tissue manipulation for histologic and molecular characterization, and prioritize relevant preclinical projects. Also, general treatment recommendations were outlined for the pediatric population. Importantly, this meeting was the starting point for meaningful collaborative international research projects. This review is a consensus summary of discussions shared and conclusions derived from this meeting.

Towards an integrated morphological and molecular WHO diagnosis of central nervous system tumors: a paradigm shift

PURPOSE OF REVIEW

It is now fully clear that information on the molecular underpinnings of tumors of the central nervous system (CNS) can be used for a more robust characterization of at least selected neoplasms. During a meeting organized in Haarlem, The Netherlands, in May 2014, about 30 neuropathologists discussed how exactly molecular information could be incorporated in the routine classification of CNS tumors.

RECENT FINDINGS

This meeting laid the groundwork for an update of the WHO CNS tumor classification that integrates histopathological and molecular findings. Furthermore, a layered diagnostic approach was proposed that not only allows for integration of relevant molecular information in the pathological diagnosis, but also retains the option for rendering a diagnosis based on histopathological analysis alone. An integrated morphological and molecular definition of CNS tumors brings new challenges as well. For example, criteria for grading within molecularly defined categories of diffuse gliomas will require modification, and some tests used in clinical practice for the detection of molecular features, may provide false positive or false negative results.

SUMMARY

The evolving paradigm shift represents a major leap forward in the diagnosis of CNS tumors that will contribute substantially to optimizing interobserver reproducibility and clinico-pathological predictions.

Immunohistochemistry on IDH 1/2, ATRX, p53 and Ki-67 substitute molecular genetic testing and predict patient prognosis in grade III adult diffuse gliomas

The molecular subgrouping of diffuse gliomas was recently found to stratify patients into prognostically distinct groups better than histological classification. Among several molecular parameters, the key molecules for the subtype diagnosis of diffuse gliomas are IDH mutation, 1p/19q co-deletion, and ATRX mutation; 1p/19q co-deletion is undetectable by immunohistochemistry, but is mutually exclusive with ATRX and p53 mutation in IDH mutant gliomas. Therefore, we applied ATRX and p53 immunohistochemistry instead of 1p/19q co-deletion analysis. The prognostic value of immunohistochemical diagnosis for Grade III gliomas was subsequently investigated. Then, the same immunohistochmical diagnostic approach was expanded for the evaluation of Grade II and IV diffuse glioma prognosis. The results indicate immunohistochemical analysis including IDH1/2, ATRX, p53, and Ki-67 index is valuable for the classification of diffuse gliomas, which is useful for the evaluation of prognosis, especially Grade III gliomas and lower-grade gliomas (i.e., Grade II and III).

Biological Significance of Mutant Isocitrate Dehydrogenase 1 and 2 in Gliomagenesis

Mutations of the isocitrate dehydrogenase (IDH) genes are considered an important event that occurs at an early stage during gliomagenesis. The mutations often occur in grade 2 or 3 gliomas and secondary glioblastomas. Most IDH mutations are associated with codon 132 and 172 in IDH1 and IDH2 in gliomas, respectively. While IDH1 and IDH2 catalyze the oxidative decarboxylation of isocitrate to form α-ketoglutarate (α-KG), IDH1 and IDH2 mutations convert α-KG to 2-hydroxyglutarate (2-HG). The accumulation of oncometabolite 2-HG is believed to lead progenitor cells into gliomas, inhibiting several α-KG-dependent enzymes, including ten-eleven translocation enzymes, histone demethylases, and prolyl hydroxylases, although the mechanisms have not been fully revealed. Herein, we review the contribution of IDH1 and IDH2 mutations to gliomagenesis.

5-hydroxymethylcytosine loss is associated with poor prognosis for patients with WHO grade II diffuse astrocytomas

Currently, the reliable prognostic biomarkers for WHO grade II diffuse astrocytomas (DA) are still limited. We investigated the relations between the level of 5-Hydroxymethylcytosine (5hmC), an oxidated production of 5-methylcytosine (5mC) by the ten eleven translocated (TET) enzymes, and clinicopathological features of glioma patients. With an identified anti-5hmC antibody, we performed immunohistochemistry in 287 glioma cases. We detected that 5hmC variably reduced in most gliomas and 5hmC reduction was closely associated with higher pathological grades and shortened survival of glioma patients. In multivariate analysis, 5hmC had no independent prognostic value in the entire patient cohort. However, multivariate analysis within subtypes of gliomas revealed that 5hmC was still a prognostic marker confined to DA. In addition, we detected that IDH1 mutation by DNA sequencing was associated with favorable survival within DA. Lastly, we detected that the combination of 5hmC/KI67 was a useful prognostic marker for restratification of DA.