Glioblastoma with oligodendroglioma component (GBM-O): molecular genetic and clinical characteristics

Current approaches in glioblastoma multiforme immunotherapy

Glioblastoma multiform (GBM) is the most prevalent CNS (central nervous system) tumor in adults, with an average survival length shorter than 2 years and rare metastasis to organs other than CNS. Despite extensive attempts at surgical resecting, the inherently permeable nature of this disease has rendered relapse nearly unavoidable. Thus, immunotherapy is a feasible alternative, as stimulated immune cells can enter into the remote and inaccessible tumor cells. Immunotherapy has revolutionized patient upshots in various malignancies and might introduce different effective ways for GBM patients. Currently, researchers are exploring various immunotherapeutic strategies in patients with GBM to target both the innate and acquired immune responses. These approaches include reprogrammed tumor-associated macrophages, the use of specific antibodies to inhibit tumor progression and metastasis, modifying tumor-associated macrophages with antibodies, vaccines that utilize tumor-specific dendritic cells to activate anti-tumor T cells, immune checkpoint inhibitors, and enhanced T cells that function against tumor cells. Despite these findings, there is still room for improving the response faults of the many currently tested immunotherapies. This study aims to review the currently used immunotherapy approaches with their molecular mechanisms and clinical application in GBM.

Radio-anatomical evaluation of clinical and radiomic profile of multi-parametric magnetic resonance imaging of de novo glioblastoma multiforme

BACKGROUND

Glioblastoma (GBM) is a fatal, fast-growing, and aggressive brain tumor arising from glial cells or their progenitors. It is a primary malignancy with a poor prognosis. The current study aims at evaluating the neuroradiological parameters of de novo GBM by analyzing the brain multi-parametric magnetic resonance imaging (mpMRI) scans acquired from a publicly available database analysis of the scans.

METHODS

The dataset used was the mpMRI scans for de novo glioblastoma (GBM) patients from the University of Pennsylvania Health System, called the UPENN-GBM dataset. This was a collection from The Cancer Imaging Archive (TCIA), a part of the National Cancer Institute. The MRIs were reviewed by a single diagnostic radiologist, and the tumor parameters were recorded, wherein all recorded data was corroborated with the clinical findings.

RESULTS

The study included a total of 58 subjects who were predominantly male (male:female ratio of 1.07:1). The mean age with SD was 58.49 (11.39) years. Mean survival days with SD were 347 (416.21) days. The left parietal lobe was the most commonly found tumor location with 11 (18.96%) patients. The mean intensity for T1, T2, and FLAIR with SD was 1.45E + 02 (20.42), 1.11E + 02 (17.61), and 141.64 (30.67), respectively (p =  < 0.001). The tumor dimensions of anteroposterior, transverse, and craniocaudal gave a z-score (significance level = 0.05) of - 2.53 (p = 0.01), - 3.89 (p < 0.001), and 1.53 (p = 0.12), respectively.

CONCLUSION

The current study takes a third-party database and reduces physician bias from interfering with study findings. Further prospective and retrospective studies are needed to provide conclusive data.

Evaluation of Immunohistochemical Expression of ALK-1 in Gliomas, WHO Grade 4 and Its Correlation with IDH1-R132H Mutation Status

BACKGROUND

Glioblastoma (GB), a grade 4 glioma is the most common primary malignant brain tumor in adults. Recently, the mutation status of isocitrate dehydrogenase (IDH) has been crucial in the treatment of GB. IDH mutant cases display a more favorable prognosis than IDH-wild type ones. The anaplastic lymphoma kinase (ALK) is expressed as a receptor tyrosine kinase in both the developing central and peripheral nervous systems. Increasing lines of evidence suggest that ALK is over-expressed in GB and represents a potential therapeutic target.

OBJECTIVES

The goal of the current study was to investigate ALK-1 immunohistochemical expression in gliomas, grade 4, besides its correlation with IDH1-R132H mutation status and the clinicopathological parameters of the tumors.

MATERIAL AND METHODS

Seventy cases of gliomas, grade 4 were tested for immunohistochemical expression of ALK-1 & IDH1-R132H in the tumor cells.

RESULTS

ALK-1 immunoexpression was detected in 22.9% of our cases and IDH1-R132H mutation was detected in 12.9% of them. ALK-1 expression (100%) was only detected in the more aggressive IDH R132H-negative GBs. ALK-1 expression was also noted in the larger-sized tumors, more in males and patients older than the mean age.  Conclusion: Our results suggest that mutations in ALK-1 may predict a more dismal prognosis since ALK expression was only noted in IDH-R132H negative GBs known to have a considerably poorer outcome compared to IDH-R132H mutant cases. GBs with detectable ALK-protein expression could potentially experience substantial clinical advantages through the utilization of newly introduced ALK inhibitors allowing personalized treatment to a subset of patients. Hence, future studies targeting ALK in IDH wildtype Glioblastomas including clinical trials on larger scales are recommended.

The STAT3-Regulated Autophagy Pathway in Glioblastoma

Glioblastoma (GBM) is the most common primary brain malignancy in adults with a dismal prognosis. Despite advances in genomic analysis and surgical technique and the development of targeted therapeutics, most treatment options are ineffective and mainly palliative. Autophagy is a form of cellular self-digestion with the goal of recycling intracellular components to maintain cell metabolism. Here, we describe some recent findings that suggest GBM tumors are more sensitive to the excessive overactivation of autophagy leading to autophagy-dependent cell death. GBM cancer stem cells (GSCs) are a subset of the GBM tumor population that play critical roles in tumor formation and progression, metastasis, and relapse, and they are inherently resistant to most therapeutic strategies. Evidence suggests that GSCs are able to adapt to a tumor microenvironment of hypoxia, acidosis, and lack of nutrients. These findings have suggested that autophagy may promote and maintain the stem-like state of GSCs as well as their resistance to cancer treatment. However, autophagy is a double-edged sword and may have anti-tumor properties under certain conditions. The role of the STAT3 transcription factor in autophagy is also described. These findings provide the basis for future research aimed at targeting the autophagy-dependent pathway to overcome the inherent therapeutic resistance of GBM in general and to specifically target the highly therapy-resistant GSC population through autophagy regulation.

Systematic Review and Individual Patient Data Analysis of Uncommon Variants of Glioblastoma: An Analysis of 196 Cases

OBJECTIVES

Different variant of GBM has been reported viz. Epithelioid Glioblastoma (GBM-E), Rhabdoid GBM (GBM-R), Small cell GBM (GBM-SC), Giant cell GBM (GBM-GC), GBM with neuro ectodermal differentiation (GBM-PNET) with unknown behavior.

MATERIALS

We conducted a systematic review and individual patient data analysis of these rare GBM variants. We searched PubMed, google search, and Cochrane library for eligible studies till July 1^st 2016 published in English language and collected data regarding age, sex, subtype and treatment received, Progression Free Survival (PFS), Overall Survival (OS). Statistical Package for social sciences (SPSS) v16 software was used for all statistical analysis.

RESULTS

We retrieved data of 196 patients with rare GBM subtypes. Among these GBM-GC is commonest (51%), followed by GBM-R (19%), GBM-PNET (13%), GBM-SC (9%) and GBM-E (8%). Median age at diagnosis was 38, 40, 43.5, 69.5 and 18 years, respectively. Male: female ratio was 2:1 for GBM-E, and 1:3 for GBM-SC. Maximal safe resection followed by adjuvant local radiation was used for most of the patients. However, 6 patients with GBM-PNET, 3 each of GBM-E, GBM-SC received adjuvant craniospinal radiation. Out of 88 patients who received chemotherapy, 64 received Temozolomide alone or combination chemotherapy containing Temozolomide. Median PFS and OS for the entire cohort were 9 and 16 months. In univariate analysis, patient with a Gross Total Resection had significantly better PFS and OS compared to those with a Sub Total Resection [23 vs. 13 months (p-0.01)]. Median OS for GBM PNET, GBM-GC, GBM-SC, GBM-R and GBM-E were 32, 18.3, 11, 12 and 7.7 months, respectively (P = 0.001). Interestingly, 31.3%, 37.8% of patients with GBM-E, GBM-R had CSF dissemination.

CONCLUSION

Overall cohort of rarer GBM variant has equivalent survival compared to GBM not otherwise specified. However, epithelioid and Rhabdoid GBM has worst survival and one third shows CSF dissemination.

Prognostic value of test(s) for O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation for predicting overall survival in people with glioblastoma treated with temozolomide

BACKGROUND

Glioblastoma is an aggressive form of brain cancer. Approximately five in 100 people with glioblastoma survive for five years past diagnosis. Glioblastomas that have a particular modification to their DNA (called methylation) in a particular region (the O6-methylguanine-DNA methyltransferase (MGMT) promoter) respond better to treatment with chemotherapy using a drug called temozolomide.

OBJECTIVES

To determine which method for assessing MGMT methylation status best predicts overall survival in people diagnosed with glioblastoma who are treated with temozolomide.

SEARCH METHODS

We searched MEDLINE, Embase, BIOSIS, Web of Science Conference Proceedings Citation Index to December 2018, and examined reference lists. For economic evaluation studies, we additionally searched NHS Economic Evaluation Database (EED) up to December 2014.

SELECTION CRITERIA

Eligible studies were longitudinal (cohort) studies of adults with diagnosed glioblastoma treated with temozolomide with/without radiotherapy/surgery. Studies had to have related MGMT status in tumour tissue (assessed by one or more method) with overall survival and presented results as hazard ratios or with sufficient information (e.g. Kaplan-Meier curves) for us to estimate hazard ratios. We focused mainly on studies comparing two or more methods, and listed brief details of articles that examined a single method of measuring MGMT promoter methylation. We also sought economic evaluations conducted alongside trials, modelling studies and cost analysis.

DATA COLLECTION AND ANALYSIS

Two review authors independently undertook all steps of the identification and data extraction process for multiple-method studies. We assessed risk of bias and applicability using our own modified and extended version of the QUality In Prognosis Studies (QUIPS) tool. We compared different techniques, exact promoter regions (5'-cytosine-phosphate-guanine-3' (CpG) sites) and thresholds for interpretation within studies by examining hazard ratios. We performed meta-analyses for comparisons of the three most commonly examined methods (immunohistochemistry (IHC), methylation-specific polymerase chain reaction (MSP) and pyrosequencing (PSQ)), with ratios of hazard ratios (RHR), using an imputed value of the correlation between results based on the same individuals.

MAIN RESULTS

We included 32 independent cohorts involving 3474 people that compared two or more methods. We found evidence that MSP (CpG sites 76 to 80 and 84 to 87) is more prognostic than IHC for MGMT protein at varying thresholds (RHR 1.31, 95% confidence interval (CI) 1.01 to 1.71). We also found evidence that PSQ is more prognostic than IHC for MGMT protein at various thresholds (RHR 1.36, 95% CI 1.01 to 1.84). The data suggest that PSQ (mainly at CpG sites 74 to 78, using various thresholds) is slightly more prognostic than MSP at sites 76 to 80 and 84 to 87 (RHR 1.14, 95% CI 0.87 to 1.48). Many variants of PSQ have been compared, although we did not see any strong and consistent messages from the results. Targeting multiple CpG sites is likely to be more prognostic than targeting just one. In addition, we identified and summarised 190 articles describing a single method for measuring MGMT promoter methylation status.

AUTHORS' CONCLUSIONS

PSQ and MSP appear more prognostic for overall survival than IHC. Strong evidence is not available to draw conclusions with confidence about the best CpG sites or thresholds for quantitative methods. MSP has been studied mainly for CpG sites 76 to 80 and 84 to 87 and PSQ at CpG sites ranging from 72 to 95. A threshold of 9% for CpG sites 74 to 78 performed better than higher thresholds of 28% or 29% in two of three good-quality studies making such comparisons.

Pre-clinical tumor models of primary brain tumors: Challenges and opportunities

Primary brain tumors are a heterogeneous group of malignancies that originate in cells of the central nervous system. A variety of models tractable for preclinical studies have been developed to recapitulate human brain tumors, allowing us to understand the underlying pathobiology and explore potential treatments. However, many promising therapeutic strategies identified using preclinical models have shown limited efficacy or failed at the clinical trial stage. The inability to develop therapeutic strategies that significantly improve survival rates in patients highlight the compelling need to revisit the design of currently available animal models and explore the use of new models that allow us to bridge the gap between promising preclinical findings and clinical translation. In this review, we discuss current strategies used to model glioblastoma, the most malignant brain tumor in adults and highlight the shortcomings of specific models that must be circumvented for the development of innovative therapeutic strategies.

Deep Learning of Imaging Phenotype and Genotype for Predicting Overall Survival Time of Glioblastoma Patients

Glioblastoma (GBM) is the most common and deadly malignant brain tumor. For personalized treatment, an accurate pre-operative prognosis for GBM patients is highly desired. Recently, many machine learning-based methods have been adopted to predict overall survival (OS) time based on the pre-operative mono- or multi-modal imaging phenotype. The genotypic information of GBM has been proven to be strongly indicative of the prognosis; however, this has not been considered in the existing imaging-based OS prediction methods. The main reason is that the tumor genotype is unavailable pre-operatively unless deriving from craniotomy. In this paper, we propose a new deep learning-based OS prediction method for GBM patients, which can derive tumor genotype-related features from pre-operative multimodal magnetic resonance imaging (MRI) brain data and feed them to OS prediction. Specifically, we propose a multi-task convolutional neural network (CNN) to accomplish both tumor genotype and OS prediction tasks jointly. As the network can benefit from learning tumor genotype-related features for genotype prediction, the accuracy of predicting OS time can be prominently improved. In the experiments, multimodal MRI brain dataset of 120 GBM patients, with as many as four different genotypic/molecular biomarkers, are used to evaluate our method. Our method achieves the highest OS prediction accuracy compared to other state-of-the-art methods.

Histo-genomics: digital pathology at the forefront of precision medicine

The toughest challenge OMICs face is that they provide extremely high molecular resolution but poor spatial information. Understanding the cellular/histological context of the overwhelming genetic data is critical for a full understanding of the clinical behavior of a malignant tumor. Digital pathology can add an extra layer of information to help visualize in a spatial and microenvironmental context the molecular information of cancer. Thus, histo-genomics provide a unique chance for data integration. In the era of a precision medicine, a four-dimensional (4D) (temporal/spatial) analysis of cancer aided by digital pathology can be a critical step to understand the evolution/progression of different cancers and consequently tailor individual treatment plans. For instance, the integration of molecular biomarkers expression into a three-dimensional (3D) image of a digitally scanned tumor can offer a better understanding of its subtype, behavior, host immune response and prognosis. Using advanced digital image analysis, a larger spectrum of parameters can be analyzed as potential predictors of clinical behavior. Correlation between morphological features and host immune response can be also performed with therapeutic implications. Radio-histomics, or the interface of radiological images and histology is another emerging exciting field which encompasses the integration of radiological imaging with digital pathological images, genomics, and clinical data to portray a more holistic approach to understating and treating disease. These advances in digital slide scanning are not without technical challenges, which will be addressed carefully in this review with quick peek at its future.

Expression of p53 & epidermal growth factor receptor in glioblastoma

Background & objectives:

Glioblastoma (GB) is the most frequent brain tumour, manifesting at any age, with a peak incidence between 45 and 75 years. Primary and secondary GBs constitute relatively distinct disease entities in evolution, in expression profiles and in therapeutic response. Histopathologically, primary and secondary GBs are indistinguishable. The aim of this investigation was to study the immunohistochemical (IHC) expression of p53 and epidermal growth factor receptor (EGFR) in GB with the objective of categorizing the morphological variants of GB into primary and secondary based on the presence of low-grade areas and knowing the variable expression of p53 and EGFR in primary and secondary GB.

Methods:

A total of 28 patients with GB were studied and categorized into primary and secondary based on the presence of low-grade areas, i.e. discernible astrocytic morphology, gemistocyte and oligodendroglia. Tumours with the presence of combination of the above features or any one of the above features were taken as secondary GB, whereas tumours with highly pleomorphic areas were considered as primary GB. IHC was done on the representative tissue blocks for p53 and EGFR.

Results:

Majority of the patients were in the fifth and sixth decades of life with a mean age of 46.96±13 yr with male preponderance (male:female 2.5:1). Mean age of presentation was 48.93±12 yr in primary and 44.69±15 yr in secondary GB. All cases of GB were classified into primary (53.57%) and secondary (46.43%) based on morphology. EGFR was more frequently expressed than p53. Based on IHC, 50 per cent of cases were classified into primary, three per cent into secondary and 47 per cent as unclassified.

Interpretation & conclusions:

Histopathological features, i.e. presence of low-grade areas, may play a role in classifying GB into primary and secondary. EGFR has a pivotal role in gliomagenesis. Combination of p53 and EGFR alone may not be sufficient to clarify GB into primary and secondary.

Identification of the tumor-suppressive function of circular RNA ITCH in glioma cells through sponging miR-214 and promoting linear ITCH expression

Circular RNAs (circRNAs) is a class of endogenous noncoding RNAs that, unlike linear RNAs, form covalently closed continuous loops and have recently shown huge capabilities as gene regulators in mammals. However, little is known about their roles in cancer initiation and progression, such as glioma. In this study, we determined the expression level of circRNA ITCH (cir-ITCH) in glioma specimens and further investigated its functional role in glioma cells. By performing Taq-man based RT-qPCR, we identified that cir-ITCH was downregulated in glioma tissues and cell lines. Receiver operating curve analysis suggested cir-ITCH showed a relatively high diagnostic accuracy. Kaplan-Meier assay revealed that decreased cir-ITCH level was associated with poor survival of glioma patients. The functional relevance of cir-ITCH was further examined by biological assays. Cir-ITCH significantly promoted the capacities of cell proliferation, migration and invasion of glioma cells. The linear isomer of cir-ITCH, ITCH gene was then identified as the down stream target. Subsequently, RNA immunoprecipitation clearly showed that cir-ITCH sponged miR-214, which further promoted the ITCH expression. Finally, the gain and loss functional assays indicate that cir-ITCH plays an anti-oncogenic role through sponging miR-214 and regulating ITCH-Wnt/β-catenin pathway. These results suggest that cir-ITCH is a tumor-suppressor gene in glioma and may serve as a promising prognostic biomarker for glioma patients. Therefore, restoration of cir-ITCH expression could be a future direction to develop a novel treatment strategy.

Major Challenges and Potential Microenvironment-Targeted Therapies in Glioblastoma

Glioblastoma (GBM) is considered one of the most malignant, genetically heterogeneous, and therapy-resistant solid tumor. Therapeutic options are limited in GBM and involve surgical resection followed by chemotherapy and/or radiotherapy. Adjuvant therapies, including antiangiogenic treatments (AATs) targeting the VEGF–VEGFR pathway, have witnessed enhanced infiltration of bone marrow-derived myeloid cells, causing therapy resistance and tumor relapse in clinics and in preclinical models of GBM. This review article is focused on gathering previous clinical and preclinical reports featuring major challenges and lessons in GBM. Potential combination therapies targeting the tumor microenvironment (TME) to overcome the myeloid cell-mediated resistance problem in GBM are discussed. Future directions are focused on the use of TME-directed therapies in combination with standard therapy in clinical trials, and the exploration of novel therapies and GBM models for preclinical studies. We believe this review will guide the future of GBM research and therapy.

Down-regulation of the long noncoding RNA-HOX transcript antisense intergenic RNA inhibits the occurrence and progression of glioma

This study aims to explore the role of long noncoding RNA (lncRNA)-HOX transcript antisense intergenic RNA (HOTAIR) in the occurrence and progression of glioma. Fresh glioma and normal brain tissues were classified into a glioma group (n = 67) and a normal group (n = 64) respectively. U87 cells were assigned into the blank, sh-NC, and sh-HOTAIR groups. Quantitative real-time polymerase chain reaction (qRT-PCR) was utilized to determine HOTAIR expression. Cell proliferation, cell cycle and cell apoptosis rates were detected by cell counting kit-8 (CCK-8) and flow cytometry (FCM). Scratch test and transwell assay were conducted for cell migration and invasion. Orthotopic glioma tumor model in nude mice was established by inoculating tumor cell suspension. Hematoxylin-Eosin (HE) staining was used to observe the growth and invasion of orthotopic glioma tumors. The expression of HOTAIR and cell viability was found to be lowest in the sh-HOTAIR group among the three groups. The sh-HOTAIR group exhibited a higher apoptotic rate and lower number of cell migration compared with the blank and sh-NC groups. Additionally, the speed of wound healing was slower, the migration distance decreased and the survival time of nude mice was extended in the sh-HOTAIR compared to the other groups. Moreover, the sh-HOTAIR group demonstrated reduced lesion sizes and inflammation, no convulsions or hemiplegia and lesser number of satellite metastases. Our findings support that down-regulation of HOTAIR could inhibit cell proliferation, promote cell apoptosis as well as suppress cell invasion and migration in the progression of glioma.

Impact of epidemiological characteristics of supratentorial gliomas in adults brought about by the 2016 world health organization classification of tumors of the central nervous system

The latest World Health Organization (WHO) classification of tumors of the central nervous system (CNS) integrates both histological and molecular features in the definition of diagnostic entities. This new approach enrolls novel entities of gliomas. In this study, we aimed to reveal the epidemiological characteristics, including age at diagnosis, gender ratio, tumor distribution and survival, of these new entities. We retrospectively reclassified 1210 glioma samples according to the 2016 CNS WHO diagnostic criteria. In our cohort, glioblastoma multiforme (GBM) with wildtype isocitrate dehydrogenase (IDH) was the most common malignant tumor in the brain. Almost all gliomas were more prevalent in males, especially in the cluster of WHO grade III gliomas and IDH-wildtype GBM. Age at diagnosis was directly proportional to tumor grade. With respect to the distribution by histology, we found that gliomas concurrent with IDH-mutant and 1p/19q-codeleted or with single IDH-mutant were mainly distributed in frontal lobe, while those with IDH-wildtype were dominant in temporal lobe. Lesions located in insular lobe were more likely to be IDH-mutant astrocytoma. In summary, our results elucidated the epidemiological characteristics as well as the regional constituents of these new gliomas entities, which could bring insights into tumorigenesis and personalized treatment of Chinese glioma population.

Glioma targeting peptide in combination with the P53 C terminus inhibits glioma cell proliferation in vitro

Glioma is a prevalent malignant primary brain tumor in adults, the treatment for which remains a challenge due to its high infiltration and recurrence. Hence, treatments that lead to the suppression of glioma cell migration and invasion may be used in addition to surgery to increase the therapeutic outcome. In this study, we aimed to construct a multifunctional protein that would exert an effect on glioma cell proliferation and migration. The protein is named GL1-P53C-11R and it consists of the glioma-targeting peptide GL1 (G), the P53 C terminus (Pc) and the cell-penetrating peptide arginine (R). GL1-P53C-R was expressed with the fusion protein ZZ and immunofluorescence analysis showed effective delivery of the fused ZZ-GL1-P53C-R protein represented as ZZ-GPcR. The ZZ-GPcR exhibited an inhibitory effect on the proliferation, migration and invasion of U87ΔEGFR cells. Western blotting results indicated that it caused significant changes in the expression levels of cell cycle and apoptotic proteins. Flow cytometric analysis showed increase apoptosis. Our findings suggest that the P53C in the fusion protein ZZ-GPcR can enter into glioma cells to exert its inhibitory effect.

Frequency and clinical significance of chromosome 7 and 10 aneuploidies, amplification of the EGFR gene, deletion of PTEN and TP53 genes, and 1p/19q deficiency in a sample of adult patients diagnosed with glioblastoma from Southern Brazil

Glioblastoma stands out as the most frequent central nervous system neoplasia, presenting a poor prognosis. The aim of this study was to verify the frequency and clinical significance of the aneuploidy of chromosomes 7 and 10, EGFR amplification, PTEN and TP53 deletions and 1p/19q deficiency in adult patients diagnosed with glioblastoma. The sample consisted of 40 patients treated from November 2011 to March 2015 at two major neurosurgery services from Southern Brazil. Molecular cytogenetic analyses of the tumor were performed through fluorescent in situ hybridization (FISH). The clinical features evaluated consisted of age, sex, tumor location, clinical symptoms, family history of cancer, type of resection and survival. The mean age of the patients was 59.3 years (ranged from 41 to 83). Most of them were males (70%). The median survival was 145 days. Chromosome 10 monosomy was detected in 52.5% of the patients, chromosome 7 polysomy in 50%, EGFR amplification in 42.5%, PTEN deletion in 35%, TP53 deletion in 22.5%, 1p deletion in 5% and 19q deletion in 7.5%. Age was shown to be a prognostic factor, and patients with lower age presented higher survival (p = 0.042). TP53 and PTEN deletions had a negative impact on survival (p = 0.011 and p = 0.037, respectively). Our data suggest that TP53 and PTEN deletions may be associated with a poorer prognosis. These findings may have importance over prognosis determination and choice of the therapy to be administered.

The Initial Area Under the Curve Derived from Dynamic Contrast-Enhanced MRI Improves Prognosis Prediction in Glioblastoma with Unmethylated MGMT Promoter

BACKGROUND AND PURPOSE

Although perfusion and permeability MR parameters have known to have prognostic value, they have reproducibility issues. Our aim was to evaluate whether the initial area under the time-to-signal intensity curve (IAUC) derived from dynamic contrast-enhanced MR imaging can improve prognosis prediction in patients with glioblastoma with known MGMT status.

MATERIALS AND METHODS

We retrospectively examined 88 patients with glioblastoma who underwent preoperative dynamic contrast-enhanced MR imaging. The means of IAUC values at 30 and 60 seconds (IAUC30_mean and IAUC60_mean) were extracted from enhancing tumors. The prognostic values of IAUC parameters for overall survival and progression-free survival were assessed with log-rank tests, according to the MGMT status. Multivariate overall survival and progression-free survival models before and after adding the IAUC parameters as covariates were explored by net reclassification improvement after receiver operating characteristic analysis for 1.5-year overall survival and 1-year progression-free survival and by random survival forest.

RESULTS

High IAUC parameters were associated with worse overall survival and progression-free survival in the unmethylated MGMT group, but not in the methylated group. In the unmethylated MGMT group, 1.5-year overall survival and 1-year progression-free survival prediction improved significantly after adding IAUC parameters (overall survival area under the receiver operating characteristic curve, 0.86; progression-free survival area under the receiver operating characteristic curve, 0.74-0.76) to the model with other prognostic factors (overall survival area under the receiver operating characteristic curve, 0.81; progression-free survival area under the receiver operating characteristic curve, 0.69; P < .05 for all) except in the case of IAUC60_mean for 1-year progression-free survival prediction (P = .059). Random survival forest models indicated that the IAUC parameters were the second or most important predictors in the unmethylated MGMT group, except in the case of the IAUC60_mean for progression-free survival.

CONCLUSIONS

IAUC can be a useful prognostic imaging biomarker in patients with glioblastoma with known MGMT status, improving prediction of glioblastoma prognosis with the unmethylated MGMT promoter status.

The new WHO 2016 classification of brain tumors-what neurosurgeons need to know

BACKGROUND

The understanding of molecular alterations of tumors has severely changed the concept of classification in all fields of pathology. The availability of high-throughput technologies such as next-generation sequencing allows for a much more precise definition of tumor entities. Also in the field of brain tumors a dramatic increase of knowledge has occurred over the last years partially calling into question the purely morphologically based concepts that were used as exclusive defining criteria in the WHO 2007 classification.

METHODS

Review of the WHO 2016 classification of brain tumors as well as a search and review of publications in the literature relevant for brain tumor classification from 2007 up to now.

RESULTS

The idea of incorporating the molecular features in classifying tumors of the central nervous system led the authors of the new WHO 2016 classification to encounter inevitable conceptual problems, particularly with respect to linking morphology to molecular alterations. As a solution they introduced the concept of a "layered diagnosis" to the classification of brain tumors that still allows at a lower level a purely morphologically based diagnosis while partially forcing the incorporation of molecular characteristics for an "integrated diagnosis" at the highest diagnostic level. In this context the broad availability of molecular assays was debated. On the one hand molecular antibodies specifically targeting mutated proteins should be available in nearly all neuropathological laboratories. On the other hand, different high-throughput assays are accessible only in few first-world neuropathological institutions. As examples oligodendrogliomas are now primarily defined by molecular characteristics since the required assays are generally established, whereas molecular grouping of ependymomas, found to clearly outperform morphologically based tumor interpretation, was rejected from inclusion in the WHO 2016 classification because the required assays are currently only established in a small number of institutions.

CONCLUSION

In summary, while neuropathologists have now encountered various challenges in the transitional phase from the previous WHO 2007 version to the new WHO 2016 classification of brain tumors, clinical neurooncologists now face many new diagnoses allowing a clearly improved understanding that could offer them more effective therapeutic opportunities in neurooncological treatment. The new WHO 2016 classification presumably presents the highest number of modifications since the initial WHO classification of 1979 and thereby forces all professionals in the field of neurooncology to intensively understand the new concepts. This review article aims to present the basic concepts of the new WHO 2016 brain tumor classification for neurosurgeons with a focus on neurooncology.

Concordance analysis and diagnostic test accuracy review of IDH1 immunohistochemistry in glioblastoma

The study investigated isocitrate dehydrogenase (IDH) 1 immunohistochemistry (IHC) positive rate and concordance rate between IDH1 IHC and molecular test in glioblastoma. The current study included 1360 glioblastoma cases from sixteen eligible studies. Meta-analysis, including subgroup analysis by antibody clones and cut-off values, for IDH1 IHC positive rate was conducted. In addition, we performed a concordance analysis and diagnostic test accuracy review between IDH1 IHC and molecular tests. The estimated rates of IDH1 IHC were 0.106 [95 % confidence interval (CI) 0.085-0.132]. The IDH1 IHC positive rate of primary and secondary glioblastomas was 0.049 (95 % CI 0.023-0.99) and 0.729 (95 % CI 0.477-0.889), respectively. The overall concordance rate between IDH1 IHC and molecular test was 0.947 (95 % CI 0.878-0.978). In IDH1 IHC-positive and negative subgroups, the concordance rate was 0.842 (95 % CI 0.591-0.952) and 0.982 (95 % CI 0.941-0.995), respectively. The pooled sensitivity and specificity for IDH1 IHC were 1.00 (95 % CI 0.82-1.00) and 0.99 (95 % CI 0.96-1.00), respectively. IDH1 IHC is an accurate test for IDH1 mutation in glioblastoma patients. Further cumulative studies for evaluation criteria of IDH1 IHC will determine how to best apply this approach in daily practice.

Farewell to GBM-O: Genomic and transcriptomic profiling of glioblastoma with oligodendroglioma component reveals distinct molecular subgroups

INTRODUCTION

Glioblastoma with oligodendroglioma component (GBM-O) was recognized as a histologic pattern of glioblastoma (GBM) by the World Health Organization (WHO) in 2007 and is distinguished by the presence of oligodendroglioma-like differentiation. To better understand the genetic underpinnings of this morphologic entity, we performed a genome-wide, integrated copy number, mutational and transcriptomic analysis of eight (seven primary, primary secondary) cases.

RESULTS

Three GBM-O samples had IDH1 (p.R132H) mutations; two of these also demonstrated 1p/19q co-deletion and had a proneural transcriptional profile, a molecular signature characteristic of oligodendroglioma. The additional IDH1 mutant tumor lacked 1p/19q co-deletion, harbored a TP53 mutation, and overall, demonstrated features most consistent with IDH mutant (secondary) GBM. Finally, five tumors were IDH wild-type (IDHwt) and had chromosome seven gains, chromosome 10 losses, and homozygous 9p deletions (CDKN2A), alterations typical of IDHwt (primary) GBM. IDHwt GBM-Os also demonstrated EGFR and PDGFRA amplifications, which correlated with classical and proneural expression subtypes, respectively.

CONCLUSIONS

Our findings demonstrate that GBM-O is composed of three discrete molecular subgroups with characteristic mutations, copy number alterations and gene expression patterns. Despite displaying areas that morphologically resemble oligodendroglioma, the current results indicate that morphologically defined GBM-O does not correspond to a particular genetic signature, but rather represents a collection of genetically dissimilar entities. Ancillary testing, especially for IDH and 1p/19q, should be used for determining these molecular subtypes.

Reduced PTEN expression and overexpression of miR-17-5p, -19a-3p, -19b-3p, -21-5p, -130b-3p, -221-3p and -222-3p by glioblastoma stem-like cells following irradiation

Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a tumor suppressor gene that induces cell apoptosis by inhibiting the PI3K/Akt signaling pathway. Glioblastoma (GBM) is a brain tumor that is resistant to irradiation and chemotherapy and, thus, is difficult to cure. GBM stem-like cells (GSCs) have been implicated as a cause of this resistance. microRNA (miRNA/miR) inhibits the expression of proteins. The objective of the present study was to identify miRNAs that target PTEN, which induces apoptosis, in irradiation-resistant GSCs. When the expression of miRNAs was examined in GSCs irradiated at 60 Gy using the human GBM A172 cell line, the expression of PTEN-targeting miR-17-5p, -19a-3p, -19b-3p, -21-5p, -130b-3p, -221-3p and -222-3p was significantly higher in irradiated GSCs than in non-irradiated cells, and the PTEN expression levels, as revealed by immunostaining, were lower in the irradiated GSCs than in the non-irradiated cells. These results suggested that the expression of PTEN was suppressed through the overexpression of PTEN-targeting miRNAs in GSCs following irradiation.

Paradoxical perfusion metrics of high-grade gliomas with an oligodendroglioma component: quantitative analysis of dynamic susceptibility contrast perfusion MR imaging

INTRODUCTION

The aim of this study is to investigate perfusion characteristics of glioblastoma with an oligodendroglioma component (GBMO) compared with conventional glioblastoma (GBM) using dynamic susceptibility contrast (DSC) perfusion magnetic resonance (MR) imaging and microvessel density (MVD).

METHODS

The study was approved by the institutional review board. Newly diagnosed high-grade glioma patients were enrolled (n = 72; 20 GBMs, 14 GBMOs, 19 anaplastic astrocytomas (AAs), 13 anaplastic oligodendrogliomas (AOs), and six anaplastic oligoastrocytomas (AOAs)). All participants underwent preoperative MR imaging including DSC perfusion MR imaging. Normalized cerebral blood volume (nCBV) values were analyzed using a histogram approach. Histogram parameters were subsequently compared across each tumor subtype and grade. MVD was quantified by immunohistochemistry staining and correlated with perfusion parameters. Progression-free survival (PFS) was assessed according to the tumor subtype.

RESULTS

GBMO displayed significantly reduced nCBV values compared with GBM, whereas grade III tumors with oligodendroglial components (AO and AOA) exhibited significantly increased nCBV values compared with AA (p < 0.001). MVD analyses revealed the same pattern as nCBV results. In addition, a positive correlation between MVD and nCBV values was noted (r = 0.633, p < 0.001). Patients with oligodendroglial tumors exhibited significantly increased PFS compared with patients with pure astrocytomas in each grade.

CONCLUSION

In contrast to grade III tumors, the presence of oligodendroglial components in grade IV tumors resulted in paradoxically reduced perfusion metrics and MVD. In addition, patients with GBMO exhibited a better clinical outcome compared with patients with GBM.

Clinical management of grade III oligodendroglioma

Oligodendrogliomas represent the third most common type of glioma, comprising 4%-15% of all gliomas and can be classified by degree of malignancy into grade II and grade III, according to WHO classification. Only 30% of oligodendroglial tumors have anaplastic characteristics. Anaplastic oligodendroglioma (AO) is often localized as a single lesion in the white matter and in the cortex, rarely in brainstem or spinal cord. The management of AO is deeply changed in the recent years. Maximal safe surgical resection followed by radiotherapy (RT) was considered as the standard of care since paramount findings regarding molecular aspects, in particular co-deletion of the short arm of chromosome 1 and the long arm of chromosome 19, revealed that these subsets of AO, benefit in terms of overall survival (OS) and progression-free survival (PFS), from the addition of chemotherapy to RT. Allelic losses of chromosomes 1p and 19q occur in 50%-70% of both low-grade and anaplastic tumors, representing a strong prognostic factor and a powerful predictor of prolonged survival. Several other molecular markers have potential clinical significance as IDH1 mutations, confirming the strong prognostic role for OS. Malignant brain tumors negatively impacts on patients' quality of life. Seizures, visual impairment, headache, and cognitive disorders can be present. Moreover, chemotherapy and RT have important side effects. For these reasons, "health-related quality of life" is becoming a topic of growing interest, investigating on physical, mental, emotional, and social well-being. Understanding the impact of medical treatment on health-related quality of life will probably have a growing effect both on health care strategies and on patients.

Prognostic Relevance of Histomolecular Classification of Diffuse Adult High-Grade Gliomas with Necrosis

Diffuse adult high-grade gliomas (HGGs) with necrosis encompass anaplastic oligodendrogliomas (AOs) with necrosis (grade III), glioblastomas (GBM, grade IV) and glioblastomas with an oligodendroglial component (GBMO, grade IV). Here, we aimed to search for prognostic relevance of histological classification and molecular alterations of these tumors. About 210 patients were included (63 AO, 56 GBM and 91 GBMO). GBMO group was split into "anaplastic oligoastrocytoma (AOA) with necrosis grade IV/GBMO," restricted to tumors showing intermingled astrocytic and oligodendroglial component, and "GBM/GBMO" based on tumors presenting oligodendroglial foci and features of GBM. Genomic arrays, IDH1 R132H expression analyses and IDH direct sequencing were performed. 1p/19q co-deletion characterized AO, whereas no IDH1 R132H expression and intact 1p/19q characterized both GBM and GBM/GBMO. AOA with necrosis/GBMO mainly demonstrated IDH1 R132H expression and intact 1p/19q. Other IDH1 or IDH2 mutations were extremely rare. Both histological and molecular classifications were predictive of progression free survival (PFS) and overall survival (OS) (P < 10(-4) ). Diffuse adult HGGs with necrosis can be split into three histomolecular groups of prognostic relevance: 1p/19q co-deleted AO, IDH1 R132H-GBM and 1p/19q intact IDH1 R132H+ gliomas that might be classified as IDH1 R132H+ GBM. Because of histomolecular heterogeneity, we suggest to remove the name GBMO.

Oligodendroglioma: pathology, molecular mechanisms and markers

For nearly a century, the diagnosis and grading of oligodendrogliomas and oligoastrocytomas has been based on histopathology alone. Roughly 20 years ago, the first glioma-associated molecular signature was found with complete chromosome 1p and 19q codeletion being particularly common in histologically classic oligodendrogliomas. Subsequently, this codeletion appeared to not only carry diagnostic, but also prognostic and predictive information, the latter aspect only recently resolved after carefully constructed clinical trials with very long follow-up times. More recently described biomarkers, including the non-balanced translocation leading to 1p/19q codeletion, promoter hypermethylation of the MGMT gene, mutations of the IDH1 or IDH2 gene, and mutations of FUBP1 (on 1p) or CIC (on 19q), have greatly enhanced our understanding of oligodendroglioma biology, although their diagnostic, prognostic, and predictive roles are less clear. It has therefore been suggested that complete 1p/19q codeletion be required for the diagnosis of 'canonical oligodendroglioma'. This transition to an integrated morphological and molecular diagnosis may result in the disappearance of oligoastrocytoma as an entity, but brings new challenges as well. For instance it needs to be sorted out how (histopathological) criteria for grading of 'canonical oligodendrogliomas' should be adapted, how pediatric oligodendrogliomas (known to lack codeletions) should be defined, which platforms and cut-off levels should ideally be used for demonstration of particular molecular aberrations, and how the diagnosis of oligodendroglioma should be made in centers/countries where molecular diagnostics is not available. Meanwhile, smart integration of morphological and molecular information will lead to recognition of biologically much more uniform groups within the spectrum of diffuse gliomas and thereby facilitate tailored treatments for individual patients.

Biomarker-driven diagnosis of diffuse gliomas

The diffuse gliomas are primary central nervous system tumors that arise most frequently in the cerebral hemispheres of adults. They are currently classified as astrocytomas, oligodendrogliomas or oligoastrocytomas and range in grade from II to IV. Glioblastoma (GBM), grade IV, is the highest grade and most common form. The diagnosis of diffuse gliomas has historically been based primarily on histopathologic features, yet these tumors have a wide range of biological behaviors that are only partially explained by morphology. Biomarkers have now become an established component of the neuropathologic diagnosis of gliomas, since molecular alterations aid in classification, prognostication and prediction of therapeutic response. Isocitrate dehydrogenase (IDH) mutations are frequent in grades II and III infiltrating gliomas of adults, as well as secondary GBMs, and are a major discriminate of biologic class. IDH mutant infiltrating astrocytomas (grades II and III), as well as secondary GBMs, are characterized by TP53 and ATRX mutations. Oligodendrogliomas are also IDH mutant, but instead are characterized by 1p/19q co-deletion and mutations of CIC, FUBP1, Notch1 and the TERT promoter. Primary GBMs typically lack IDH mutations and demonstrate EGFR, PTEN, TP53, PDGFRA, NF1 and CDKN2A/B alterations and TERT promoter mutations. Pediatric gliomas differ in their spectrum of disease from those in adults; high grade gliomas occurring in children frequently have mutations in H3F3A, ATRX and DAXX, but not IDH. Circumscribed, low grade gliomas, such as pilocytic astrocytoma, pleomorphic xanthoastrocytoma and ganglioglioma, need to be distinguished from diffuse gliomas in the pediatric population. These gliomas often harbor mutations or activating gene rearrangements in BRAF.

Novel genotype-phenotype associations in human cancers enabled by advanced molecular platforms and computational analysis of whole slide images

Technological advances in computing, imaging, and genomics have created new opportunities for exploring relationships between histology, molecular events, and clinical outcomes using quantitative methods. Slide scanning devices are now capable of rapidly producing massive digital image archives that capture histological details in high resolution. Commensurate advances in computing and image analysis algorithms enable mining of archives to extract descriptions of histology, ranging from basic human annotations to automatic and precisely quantitative morphometric characterization of hundreds of millions of cells. These imaging capabilities represent a new dimension in tissue-based studies, and when combined with genomic and clinical endpoints, can be used to explore biologic characteristics of the tumor microenvironment and to discover new morphologic biomarkers of genetic alterations and patient outcomes. In this paper, we review developments in quantitative imaging technology and illustrate how image features can be integrated with clinical and genomic data to investigate fundamental problems in cancer. Using motivating examples from the study of glioblastomas (GBMs), we demonstrate how public data from The Cancer Genome Atlas (TCGA) can serve as an open platform to conduct in silico tissue-based studies that integrate existing data resources. We show how these approaches can be used to explore the relation of the tumor microenvironment to genomic alterations and gene expression patterns and to define nuclear morphometric features that are predictive of genetic alterations and clinical outcomes. Challenges, limitations, and emerging opportunities in the area of quantitative imaging and integrative analyses are also discussed.

Prognosis of Glioblastoma With Oligodendroglioma Component is Associated With the IDH1 Mutation and MGMT Methylation Status

Glioblastoma (GBM) with oligodendroglioma component (GBMO) is a newly described GBM subtype in the 2007 World Health Organization classification. However, its biological and genetic characteristics are largely unknown. We investigated the clinicopathological and molecular features of 34 GBMOs and compared the survival rate of these patients with those of patients with astrocytoma, oligodendroglioma, anaplastic oligoastrocytoma (AOA), and conventional GBMs in our hospital. GBMO could be divided into two groups based on the presence of an IDH1 mutation. The IDH1 mutation was more frequently found in secondary GBMO, which had lower frequencies of EGFR amplification but higher MGMT methylation than the wild type IDH1 group, and patients with mutant IDH1 GBMO were on average younger than those with wild-type IDH1. Therefore, GBMO is a clinically and molecularly heterogeneous subtype, largely belonging to a proneural and classical subtype of GBM. The survival rate of GBMO patients itself was worse than that of AOA patients but not significantly better than that of conventional GBM patients. GBMO survival was independent of the dominant histopathological subtype i.e., astrocyte-dominant or oligodendroglioma -dominant, but it was significantly associated with the IDH1 mutation and MGMT methylation status. Therefore, GBMO should be regarded as a separate entity from AOA and must be classified as a subtype of GBM. However, further study is needed to determine whether it is a pathologic variant or a pattern of GBM because GBMO has a similar prognosis to conventional GBMs.

Molecular stereotactic biopsy technique improves diagnostic accuracy and enables personalized treatment strategies in glioma patients

BACKGROUND

In gliomas molecular biomarkers are increasingly gaining diagnostic, prognostic and predictive significance. Determination of biomarker status after biopsy is important as not all patients are eligible for open tumor resection. We developed and validated prospectively (6/10-12/11) a protocol allowing for both reliable determination of multiple biomarkers and representative histological diagnoses from small-sized biopsies.

METHODS

All molecular stereotactic biopsies were performed according to a detailed workflow. The selection of specimens best suited for molecular analyses was intra-operatively guided by the attending neuropathologist. Postoperative screening was done by methylation specific PCR using two distinct cryopreserved specimens to test for reproducibility of the findings and to rule out contamination. The DNA of a single best-suited specimen (1 mm(3)) was subjected to detailed molecular analysis (MGMT promoter methylation, IDH1/2 mutational status, LOH 1p and/or 19q).

RESULTS

159 consecutively enrolled untreated gliomas were analyzed (94 glioblastomas, 2 gliosarcomas, 24 anaplastic astrocytomas, 10 oligo-tumors grade II/III, 20 grade II astrocytomas and 9 pilocytic astrocytomas). Transient morbidity was 2 %. Overall, the drop-out rate due to tissue contamination was 0.4 %. Median time from biopsy to histological and molecular genetic analyses was 3 and 5 days, respectively. Distributions of the respective biomarker status for tumor subgroups were consistent with the literature. The final histological diagnosis was changed/modified in 5/159 patients according to molecular findings. Treatment after molecular biopsy was highly personalized.

CONCLUSIONS

Molecular stereotactic biopsy is feasible and safe, can be implemented in daily clinical practice, improves diagnostic precision and enables personalized treatment.

Epidemiologic and molecular prognostic review of glioblastoma

Glioblastoma multiforme (GBM) is the most common and aggressive primary central nervous system malignancy with a median survival of 15 months. The average incidence rate of GBM is 3.19/100,000 population, and the median age of diagnosis is 64 years. Incidence is higher in men and individuals of white race and non-Hispanic ethnicity. Many genetic and environmental factors have been studied in GBM, but the majority are sporadic, and no risk factor accounting for a large proportion of GBMs has been identified. However, several favorable clinical prognostic factors are identified, including younger age at diagnosis, cerebellar location, high performance status, and maximal tumor resection. GBMs comprise of primary and secondary subtypes, which evolve through different genetic pathways, affect patients at different ages, and have differences in outcomes. We report the current epidemiology of GBM with new data from the Central Brain Tumor Registry of the United States 2006 to 2010 as well as demonstrate and discuss trends in incidence and survival. We also provide a concise review on molecular markers in GBM that have helped distinguish biologically similar subtypes of GBM and have prognostic and predictive value.

How our practice of histopathology, especially tumour pathology has changed in the last two decades: reflections from a major referral center in Pakistan

Continued advances in the field of histo-pathology (and cyto-pathology) over the past two decades have resulted in dramatic changes in the manner in which these disciplines are now practiced. This is especially true in the setting of a large university hospital where the role of pathologists as clinicians (diagnosticians), undergraduate and postgraduate educators, and researchers has evolved considerably. The world around us has changed significantly during this period bringing about a considerable change in our lifestyles and the way we live. This is the world of the internet and the world-wide web, the world of Google and Wikipedia, of Youtube and Facebook where anyone can obtain any information one desires at the push of a button. The practice of histo (and cyto) pathology has also evolved in line with these changes. For those practicing this discipline in a poor, developing country these changes have been breathtaking. This is an attempt to document these changes as experienced by histo (and cyto) pathologists practicing in the biggest center for Histopathology in Pakistan, a developing country in South Asia with a large (180 million) and ever growing population. The Section of Histopathology, Department of Pathology and Microbiology at the Aga Khan University Hospital (AKUH) in Karachi, Pakistan's largest city has since its inception in the mid-1980s transformed the way histopathology is practiced in Pakistan by incorporating modern methods and rescuing histopathology in Pakistan from the primitive and outdated groove in which it was stuck for decades. It set histopathology in Pakistan firmly on the path of modernity and change which are essential for better patient management and care through accurate and complete diagnosis and more recently prognostic and predictive information as well.

C-terminally truncated form of αB-crystallin is associated with IDH1 R132H mutation in anaplastic astrocytoma

Malignant gliomas are the most common human primary brain tumors. Point mutation of amino acid arginine 132 to histidine (R132H) in the IDH1 protein leads to an enzymatic gain-of-function and is thought to promote gliomagenesis. Little is known about the downstream effects of the IDH1 mutation on protein expression and how and whether changes in protein expression are involved in tumor formation or propagation. In the current study, we used 2D DIGE (difference gel electrophoresis) and mass spectrometry to analyze differences in protein expression between IDH1(R132H) mutant and wild type anaplastic (grade III) astrocytoma from human brain cancer tissues. We show that expression levels of many proteins are altered in IDH1(R132H) mutant anaplastic astrocytoma. Some of the most over-expressed proteins in the mutants include several forms of αB-crystallin, a small heat-shock and anti-apoptotic protein. αB-crystallin proteins are elevated up to 22-fold in IDH1(R132H) mutant tumors, and αB-crystallin expression appears to be controlled at the post-translational level. We identified the most abundant form of αB-crystallin as a low molecular weight species that is C-terminally truncated. We also found that overexpression of αB-crystallin can be induced by transfecting U251 human glioblastoma cell lines with the IDH1(R132H) mutation. In conclusion, the association of a C-terminally truncated form of αB-crystallin protein with the IDH1(R132H) mutation is a novel finding that could impact apoptosis and stress response in IDH1 mutant glioma.

Using the molecular classification of glioblastoma to inform personalized treatment

Glioblastoma is the most common and most aggressive diffuse glioma, associated with short survival and uniformly fatal outcome, irrespective of treatment. It is characterized by morphological, genetic and gene-expression heterogeneity. The current standard of treatment is maximal surgical resection, followed by radiation, with concurrent and adjuvant chemotherapy. Due to the heterogeneity, most tumours develop resistance to treatment and shortly recur. Following recurrence, glioblastoma is quickly fatal in the majority of cases. Recent genetic molecular advances have contributed to a better understanding of glioblastoma pathophysiology and disease stratification. In this paper we review basic glioblastoma pathophysiology, with emphasis on clinically relevant genetic molecular alterations and potential targets for further drug development.

Machine-based morphologic analysis of glioblastoma using whole-slide pathology images uncovers clinically relevant molecular correlates

Pathologic review of tumor morphology in histologic sections is the traditional method for cancer classification and grading, yet human review has limitations that can result in low reproducibility and inter-observer agreement. Computerized image analysis can partially overcome these shortcomings due to its capacity to quantitatively and reproducibly measure histologic structures on a large-scale. In this paper, we present an end-to-end image analysis and data integration pipeline for large-scale morphologic analysis of pathology images and demonstrate the ability to correlate phenotypic groups with molecular data and clinical outcomes. We demonstrate our method in the context of glioblastoma (GBM), with specific focus on the degree of the oligodendroglioma component. Over 200 million nuclei in digitized pathology slides from 117 GBMs in the Cancer Genome Atlas were quantitatively analyzed, followed by multiplatform correlation of nuclear features with molecular and clinical data. For each nucleus, a Nuclear Score (NS) was calculated based on the degree of oligodendroglioma appearance, using a regression model trained from the optimal feature set. Using the frequencies of neoplastic nuclei in low and high NS intervals, we were able to cluster patients into three well-separated disease groups that contained low, medium, or high Oligodendroglioma Component (OC). We showed that machine-based classification of GBMs with high oligodendroglioma component uncovered a set of tumors with strong associations with PDGFRA amplification, proneural transcriptional class, and expression of the oligodendrocyte signature genes MBP, HOXD1, PLP1, MOBP and PDGFRA. Quantitative morphologic features within the GBMs that correlated most strongly with oligodendrocyte gene expression were high nuclear circularity and low eccentricity. These findings highlight the potential of high throughput morphologic analysis to complement and inform human-based pathologic review.