Isocitrate dehydrogenase-1 mutations as prognostic biomarker in glioblastoma multiforme patients in West Bohemia

IDH1 mutation is detectable in plasma cell-free DNA and is associated with survival outcome in glioma patients

BACKGROUND

Circulating cell-free DNA (cfDNA, liquid biopsy) is a powerful tool to detect molecular alterations. However, depending on tumor characteristics, biology and anatomic localization, cfDNA detection and analysis may be challenging. Gliomas are enclosed into an anatomic sanctuary, which obstacles the release of cfDNA into the peripheral blood. Therefore, the advantages of using liquid biopsy for brain tumors is still to be confirmed. The present study evaluates the ability of liquid biopsy to detect IDH1 mutations and its correlation with survival and clinical characteristics of glioma patients.

METHODS

Blood samples obtained from glioma patients were collected after surgery prior to the adjuvant therapy. cfDNA was extracted from plasma and IDH1 p.R132H mutation analysis was performed on a digital droplet PCR. χ2-test and Cohen k were used to assess the correlation between plasma and tissue IDH1 status, while Kaplan Meier curve and Cox regression analysis were applied to survival analysis. Statistical calculations were performed by MedCalc and GraphPad Prism software.

RESULTS

A total of 67 samples were collected. A concordance between IDH1 status in tissue and in plasma was found (p = 0.0024), and the presence of the IDH1 mutation both in tissue (138.8 months vs 24.4, p < 0.0001) and cfDNA (116.3 months vs 35.8, p = 0.016) was associated with longer median OS. A significant association between IDH1 mutation both in tissue and cfDNA, age, tumor grade and OS was demonstrated by univariate Cox regression analysis. No statistically significant association between IDH1 mutation and tumor grade was found (p = 0.10).

CONCLUSIONS

The present study demonstrates that liquid biopsy may be used in brain tumors to detect IDH1 mutation which represents an important prognostic biomarker in patients with different types of gliomas, being associated to OS.

Endoglin (CD105) and proliferation index in recurrent glioblastoma treated with anti-angiogenic therapy

Introduction

CD105 is an angiogenic biomarker that is useful to determine the microvessel density (MVD) within a tumor, namely, in highly vascularized tumors like glioblastoma (GBM). However, its expression has shown inconsistent associations with the prognosis of GBM patients. The aim of this study was to evaluate the value of MVD-CD105 (microvessel density assessed with anti-CD105 antibody) and Ki-67 (proliferation index marker) as prognostic and therapy response biomarkers, specifically in primary tumors and in recurrent tumoral specimens of a cohort of GBM patients treated with bevacizumab upon recurrence.

Materials and methods

We conducted a retrospective study of 102 consecutive GBM patients treated with bevacizumab upon recurrence at CHUSJ between 2010 and 2017. Demographic, clinical, and survival data of all patients were collected and analyzed. The tissue expression of MVD-CD105 and Ki-67 in primary and recurrent specimens was correlated with progression-free survival after temozolomide (PFS-1), progression-free survival after bevacizumab (PFS-2), and overall survival (OS).

Results

The immunohistochemical expression score for MVD-CD105 was similar in primary and recurrent tumoral specimens (mean scores of 15 and 16, respectively). Likewise, the mean Ki-67 expression was similar in primary (mean of 31% of tumor cells) and recurrent tumoral specimens (mean of 29% of tumor cells). MVD-CD105 expression in primary tumors had no impact on PFS-1, PFS-2, or OS. At recurrence, patients whose tumors showed increased MVD-CD105 had worse median PFS-2 (2 vs. 8 months, p = 0.045) and OS (17 vs. 26 months, p = 0.007) compared to those whose tumors showed lower MVD-CD105. CD105 tumoral pattern and localization had no impact on prognosis. Ki-67 expression was not associated with differences in survival outcomes.

Conclusion

In this study, higher MVD-CD105 expression in recurrent GBM patients seems to be associated with a worse PFS-2 and OS while portending no prognostic significance in the primary tumors. This highlights the importance of keeping track of the molecular evolution of the tumor over the course of the disease.

Molecular Biomarker Testing for the Diagnosis of Diffuse Gliomas

CONTEXT.—

The diagnosis and clinical management of patients with diffuse gliomas (DGs) have evolved rapidly over the past decade with the emergence of molecular biomarkers that are used to classify, stratify risk, and predict treatment response for optimal clinical care.

OBJECTIVE.—

To develop evidence-based recommendations for informing molecular biomarker testing for pediatric and adult patients with DGs and provide guidance for appropriate laboratory test and biomarker selection for optimal diagnosis, risk stratification, and prediction.

DESIGN.—

The College of American Pathologists convened an expert panel to perform a systematic review of the literature and develop recommendations. A systematic review of literature was conducted to address the overarching question, "What ancillary tests are needed to classify DGs and sufficiently inform the clinical management of patients?" Recommendations were derived from quality of evidence, open comment feedback, and expert panel consensus.

RESULTS.—

Thirteen recommendations and 3 good practice statements were established to guide pathologists and treating physicians on the most appropriate methods and molecular biomarkers to include in laboratory testing to inform clinical management of patients with DGs.

CONCLUSIONS.—

Evidence-based incorporation of laboratory results from molecular biomarker testing into integrated diagnoses of DGs provides reproducible and clinically meaningful information for patient management.

Intravoxel incoherent motion magnetic resonance imaging in predicting IDH1 gene mutations in high-grade gliomas

BACKGROUND

Intravoxel incoherent motion (IVIM) magnetic resonance imaging (MRI) has been applied to gliomas; however, the relationships between its parameters and isocitrate dehydrogenase 1 (IDH1) mutations in gliomas remain to be investigated.

PURPOSE

To investigate the value of IVIM in predicting IDH1 mutations in high-grade gliomas before surgery.

MATERIAL AND METHODS

A total of 72 patients with pathologically confirmed high-grade gliomas underwent conventional brain MRI and IVIM from September 2016 to May 2020. Among them, 22 cases were IDH1 mutant and 50 cases were IDH1 wild type. The independent samples t test (normal distribution and homogeneity of variance) or Mann-Whitney rank-sum test (non-normal distribution or heterogeneity of variance) was conducted, and receiver operating characteristic curves were generated to determine parameters for distinguishing IDH1-mutated from IDH1 wild-type high-grade gliomas. These parameters included apparent diffusion coefficient (ADC), true diffusivity (D), pseudo-diffusivity (D*), and perfusion fraction (f).

RESULTS

ADC, D, and f were significantly higher in IDH1-mutated gliomas than in IDH1 wild-type gliomas (P < 0.05 for all). There was no significant difference in the D* value between the two groups (P = 0.053). The areas under the curve of ADC, D, and f in predicting IDH1 mutations in gliomas were 0.798, 0.810, and 0.823, respectively. The specificity of ADC was highest (80.0%), and the sensitivity of the f value was the highest (100.0%).

CONCLUSION

IVIM can be used for the quantitative prediction of IDH1 mutations in high-grade gliomas before surgery, and the f value is the most effective.

Identification of Hub Genes and Key Pathways Associated with Anti-VEGF Resistant Glioblastoma Using Gene Expression Data Analysis

Anti-VEGF therapy is considered to be a useful therapeutic approach in many tumors, but the low efficacy and drug resistance limit its therapeutic potential and promote tumor growth through alternative mechanisms. We reanalyzed the gene expression data of xenografts of tumors of bevacizumab-resistant glioblastoma multiforme (GBM) patients, using bioinformatics tools, to understand the molecular mechanisms of this resistance. An analysis of the gene set data from three generations of xenografts, identified as 646, 873 and 1220, differentially expressed genes (DEGs) in the first, fourth and ninth generations, respectively, of the anti-VEGF-resistant GBM cells. Gene Ontology (GO) and pathway enrichment analyses demonstrated that the DEGs were significantly enriched in biological processes such as angiogenesis, cell proliferation, cell migration, and apoptosis. The protein–protein interaction network and module analysis revealed 21 hub genes, which were enriched in cancer pathways, the cell cycle, the HIF1 signaling pathway, and microRNAs in cancer. The VEGF pathway analysis revealed nine upregulated (IL6, EGFR, VEGFA, SRC, CXCL8, PTGS2, IDH1, APP, and SQSTM1) and five downregulated hub genes (POLR2H, RPS3, UBA52, CCNB1, and UBE2C) linked with several of the VEGF signaling pathway components. The survival analysis showed that three upregulated hub genes (CXCL8, VEGFA, and IDH1) were associated with poor survival. The results predict that these hub genes associated with the GBM resistance to bevacizumab may be potential therapeutic targets or can be biomarkers of the anti-VEGF resistance of GBM.

Potential roads for reaching the summit: an overview on target therapies for high-grade gliomas

Background:

The tailored targeting of specific oncogenes represents a new frontier in the treatment of high-grade glioma in the pursuit of innovative and personalized approaches. The present study consists in a wide-ranging overview of the target therapies and related translational challenges in neuro-oncology.

Methods:

A review of the literature on PubMed/MEDLINE on recent advances concerning the target therapies for treatment of central nervous system malignancies was carried out. In the Medical Subject Headings, the terms “Target Therapy”, “Target drug” and “Tailored Therapy” were combined with the terms “High-grade gliomas”, “Malignant brain tumor” and “Glioblastoma”. Articles published in the last five years were further sorted, based on the best match and relevance. The ClinicalTrials.gov website was used as a source of the main trials, where the search terms were “Central Nervous System Tumor”, “Malignant Brain Tumor”, “Brain Cancer”, “Brain Neoplasms” and “High-grade gliomas”.

Results:

A total of 137 relevant articles and 79 trials were selected. Target therapies entailed inhibitors of tyrosine kinases, PI3K/AKT/mTOR pathway, farnesyl transferase enzymes, p53 and pRB proteins, isocitrate dehydrogenases, histone deacetylases, integrins and proteasome complexes. The clinical trials mostly involved combined approaches. They were phase I, II, I/II and III in 33%, 42%, 16%, and 9% of the cases, respectively.

Conclusion:

Tyrosine kinase and angiogenesis inhibitors, in combination with standard of care, have shown most evidence of the effectiveness in glioblastoma. Resistance remains an issue. A deeper understanding of the molecular pathways involved in gliomagenesis is the key aspect on which the translational research is focusing, in order to optimize the target therapies of newly diagnosed and recurrent brain gliomas. (www.actabiomedica.it)

Radiomic MRI Phenotyping of Glioblastoma: Improving Survival Prediction

Purpose To investigate whether radiomic features at MRI improve survival prediction in patients with glioblastoma multiforme (GBM) when they are integrated with clinical and genetic profiles. Materials and Methods Data in patients with a diagnosis of GBM between December 2009 and January 2017 (217 patients) were retrospectively reviewed up to May 2017 and allocated to training and test sets (3:1 ratio). Radiomic features (n = 796) were extracted from multiparametric MRI. A random survival forest (RSF) model was trained with the radiomic features along with clinical and genetic profiles (O-6-methylguanine-DNA-methyltransferase promoter methylation and isocitrate dehydrogenase 1 mutation statuses) to predict overall survival (OS) and progression-free survival (PFS). The RSF models were validated on the test set. The incremental values of radiomic features were evaluated by using the integrated area under the receiver operating characteristic curve (iAUC). Results The 217 patients had a mean age of 57.9 years, and there were 87 female patients (age range, 22-81 years) and 130 male patients (age range, 17-85 years). The median OS and PFS of patients were 352 days (range, 20-1809 days) and 264 days (range, 21-1809 days), respectively. The RSF radiomics models were successfully validated on the test set (iAUC, 0.652 [95% confidence interval {CI}, 0.524, 0.769] and 0.590 [95% CI: 0.502, 0.689] for OS and PFS, respectively). The addition of a radiomics model to clinical and genetic profiles improved survival prediction when compared with models containing clinical and genetic profiles alone (P = .04 and .03 for OS and PFS, respectively). Conclusion Radiomic MRI phenotyping can improve survival prediction when integrated with clinical and genetic profiles and thus has potential as a practical imaging biomarker. © RSNA, 2018 Online supplemental material is available for this article. See also the editorial by Jain and Lui in this issue.

Multi-Label Nonlinear Matrix Completion With Transductive Multi-Task Feature Selection for Joint MGMT and IDH1 Status Prediction of Patient With High-Grade Gliomas

The O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation and isocitrate dehydrogenase 1 (IDH1) mutation in high-grade gliomas (HGG) have proven to be the two important molecular indicators associated with better prognosis. Traditionally, the statuses of MGMT and IDH1 are obtained via surgical biopsy, which has limited their wider clinical implementation. Accurate presurgical prediction of their statuses based on preoperative multimodal neuroimaging is of great clinical value for a better treatment plan. Currently, the available data set associated with this study has several challenges, such as small sample size and complex, nonlinear (image) feature-to-(molecular) label relationship. To address these issues, we propose a novel multi-label nonlinear matrix completion (MNMC) model to jointly predict both MGMT and IDH1 statuses in a multi-task framework. Specifically, we first employ a nonlinear random Fourier feature mapping to improve the linear separability of the data, and then use transductive multi-task feature selection (performed in a nonlinearly transformed feature space) to refine the imputed soft labels, thus alleviating the overfitting problem caused by small sample size. We further design an optimization algorithm with a guaranteed convergence ability based on a block prox-linear method to solve the proposed MNMC model. Finally, by using a single-center, multimodal brain imaging and molecular pathology data set of HGG, we derive brain functional and structural connectomics features to jointly predict MGMT and IDH1 statuses. Results demonstrate that our proposed method outperforms the previously widely used single- and multi-task machine learning methods. This paper also shows the promise of utilizing brain connectomics for HGG prognosis in a non-invasive manner.

IDH Mutation Analysis in Glioma Patients by CADMA Compared with SNaPshot Assay and two Immunohistochemical Methods

Mutations in IDH1/2 genes are a marker of good prognosis for glioma patients, associated with low grade gliomas and secondary glioblastomas. Immunohistochemistry and Sanger sequencing are current standards for IDH1/2 genotyping while many other methods exist. The aim of this study was to validate Competitive amplification of differentially melting amplicons (CADMA) PCR for IDH genotyping by comparison with SNaPshot assay and two immunohistochemical methods. In our study, 87 glioma patients (46 from Olomouc and 41 from Ostrava) were analyzed. IDH1/2 mutations in native bioptical samples were analyzed at DNA level by CADMA and SNaPshot while IDH1 mutations in FFPE samples were analyzed at protein level by two IHC methods. CADMA PCR sensitivity for IDH1 was 96.4% and specificity 100% for 86 concluded samples. SNaPshot assay sensitivity was 92.9% and specificity of 100% for 85 concluded samples. IHC in the laboratory no. 2 reached sensitivity 85.7% and specificity 100% for 86 concluded samples. IHC in the laboratory no. 4 reached sensitivity of 96.4% and specificity of 79.7% in 74 concluded samples. Only one IDH2 mutation was found by SNaPshot while CADMA yielded false negative result. In conclusion, CADMA is a valid method for IDH1 p.(R132H) testing with higher sensitivity than SNaPshot assay. Also, molecular genetic methods of IDH1 testing from native samples were more robust than IHC from FFPE.

IDH1 mutation is associated with lower expression of VEGF but not microvessel formation in glioblastoma multiforme

Introduction

Glioblastoma multiforme (GBM) represents the most malignant primary brain tumor characterized by pathological vascularization. Mutations in isocitrate dehydrogenases 1 and 2 (IDH1 and IDH2) were observed in GBM. We aimed to assess the intra-tumor hypoxia, angiogenesis and microvessel formation in GBM and to find their associations with IDH1 mutation status and patients prognosis.

Methods

52 patients with a diagnosis of GBM were included into the study. IDH1 R132H mutation was assessed by RT-PCR from FFPE tumor samples obtained during surgery. The expression of markers of hypoxia (HIF2α), angiogenesis (VEGF), tumor microvascularity (CD31, CD34, vWF, CD105), and proliferation (Ki-67) were assessed immunohistochemically (IHC). IDH1 mutation and IHC markers were correlated with the patient survival.

Results

20 from 52 GBM tumor samples comprised IDH1 R132H mutation (38.5%). The majority of mutated tumors were classified as secondary glioblastomas (89.9%). Patients with IDH1 mutated tumors experienced better progression-free survival (P = 0.037) as well as overall survival (P = 0.035) compared with wild type tumors. The significantly lower expression of VEGF was observed in GBM with IDH1 mutation than in wild type tumors (P = 0.01). No such association was found for microvascular markers. The increased expression of newly-formed microvessels (ratio CD105/CD31) in tumor samples was associated with worse patient’s progression-free survival (P = 0.026).

Summary

No increase in HIF/VEGF-mediated angiogenesis was observed in IDH1-mutated GBM compared with IDH1 wild type tumors. The histological assessment of the portion of newly-formed microvessels in tumor tissue can be used for the prediction of GBM patient’s prognosis.

IDH1 mutation is associated with a higher preoperative seizure incidence in low-grade glioma: A systematic review and meta-analysis

PURPOSE

Gliomas, particularly low-grade gliomas (LGGs), are highly epileptogenic. Seizure is the most common presenting sign of LGG patients and significantly decreases their quality of life. Accordingly, there is a need for a better understanding of the mechanisms and risk factors of glioma-related epilepsy. The current study aimed to perform a comprehensive meta-analysis to investigate the correlation of isocitrate-dehydrogenase 1 (IDH1), an important molecular biomarker for glioma classification and prognosis, to preoperative seizure incidence in LGG.

METHODS

PUBMED, EMBASE, and Web of Science databases were searched for relevant studies. The odds ratio (OR) and corresponding 95% confidence interval (CI) were used as the primary measures to assess the correlation between IDH1 mutation and preoperative seizure incidence.

RESULTS

A total of 722 LGG patients, including 555 patients with IDH1 mutation and 167 patients with wild-type IDH1 were enrolled in the current meta-analysis. The pooled OR was 2.47 (95% CI 1.70-3.57, Z = 4.78, p < 0.01). No significant heterogeneity was observed among all included studies and no publication bias was identified.

CONCLUSION

The current meta-analysis identified that IDH1 mutation was correlated to a higher preoperative seizure incidence in LGG. This result would generate impetus for research on the mechanisms behind this correlation, and provide a new idea for the individualized treatment of glioma-related epilepsy.

Genetic alterations of IDH1 and Vegf in brain tumors

BACKGROUND

This study evaluates the presence of R132H mutation in isocitrate dehydrogenase (IDH1) gene and the vascular endothelial growth factor (VEGF) +936 C/T polymorphism in brain tumors. The impact of these genetic alterations on overall survival (OS) and progression free survival (PFS) was evaluated.

METHODS

A cohort of 80 patients surgically treated at Hospital Clínico San Carlos, Madrid, between March 2004 and November 2012, was analyzed. Tumors were distributed in 73 primary brain tumors (gliomas, meningiomas, hemangiopericytomas and hemangioblastomas) and seven secondary tumors evolved from a low grade glioma, thus providing a mixed sample.

RESULTS

IDH1^R132H gene mutation was found in 12 patients (15%) and appears more frequently in secondary tumors (5 (71.4%) whereas in 7 (9.7%) primary tumors (p < .001)). The mutation is related to WHO grade II in primary tumors and a supratentorial location in secondary tumors. The OS analysis for IDH1 showed a tendency towards a better prognosis of the tumors containing the mutation (p = .059).The IDH1^R132H mutation confers a better PFS (p = .025) on primary tumors. The T allele of VEFG +936 C/T polymorphism was found in 16 patients (20%). No relation was found between this polymorphism and primary or secondary tumor, neither with OS or PFS.

CONCLUSIONS

IDH1^R132H gene mutation is exclusive in supratentorial tumors and more frequent in secondary ones, with a greater survival trend and better PFS in patients who carry it. The T allele of VEGF +936 C/T polymorphism is more common in primary tumors, although there is no statistical relation with survival.

Association of The IDH1 C.395G>A (R132H) Mutation with Histological Type in Malay Brain Tumors

Background:

Brain tumors, constituting one of the most deadly forms of cancer worldwide, result from the accumulation of multiple genetic and epigenetic alterations in genes and signaling pathways. Isocitrate dehydrogenase enzyme isoform 1 (IDH1) mutations are frequently identified in primary brain tumors and acute myeloid leukemia. Studies on IDH1 gene mutations have been extensively performed in various populations worldwide but not in Malaysia. This work was conducted to study the prevalence of IDH1 c.395G>A (R132H) hotspot mutations in a group of Malaysian patients with brain tumors in order to gain local data for the IDH1 mutation profile in our population.

Methods:

Mutation analysis of c.395G>A (R132H) of IDH1 was performed in 40 brain tumor specimens by the polymerase chain reaction-restriction fragment length polymorphism method (PCR-RFLP) and then verified by direct sequencing. Associations between the IDH1 c.395G>A (R132H) mutation and clinicopathologic characteristics were also analyzed.

Results:

The IDH1 c.395G>A (R132H) mutation was detected in 14/40 patients (35%). A significant association was found with histological tumor types, but not with age, gender and race.

Conclusions:

IDH1 is frequently mutated and associated with histological subtypes in Malay brain tumors.

Glioblastoma, hypoxia and autophagy: a survival-prone 'ménage-à-trois'

Glioblastoma multiforme is the most common and the most aggressive primary brain tumor. It is characterized by a high degree of hypoxia and also by a remarkable resistance to therapy because of its adaptation capabilities that include autophagy. This degradation process allows the recycling of cellular components, leading to the formation of metabolic precursors and production of adenosine triphosphate. Hypoxia can induce autophagy through the activation of several autophagy-related proteins such as BNIP3, AMPK, REDD1, PML, and the unfolded protein response-related transcription factors ATF4 and CHOP. This review summarizes the most recent data about induction of autophagy under hypoxic condition and the role of autophagy in glioblastoma.

Ollier disease with anaplastic astrocytoma: A review of the literature and a unique case

Background:

Ollier disease is a rare, nonfamilial disorder that primary affects the long bones and cartilage of joints with multiple enchondromas. It is associated with a higher risk of central nervous system (CNS) malignancies; although the incidence is unknown.

Case Description:

Here, we present the case of a 55-year-old woman who developed an anaplastic astrocytoma with a known diagnosis of Ollier disease with a survival time of over 3 years.

Conclusion:

This report draws attention to the rarity of this disease and the paucity of information regarding CNS involvement in Ollier disease, as well as reviews the current literature.

Frontal glioblastoma multiforme may be biologically distinct from non-frontal and multilobar tumors

Glioblastoma multiforme (GBM) is the most common primary brain tumor in adults and carries a grim prognosis. Lobar GBM, notably those localized to the frontal lobe, are generally more amenable to complete surgical resection, and may carry a better prognosis. The biology of differently localized GBM has been reported scarcely in terms of prognostic markers, including isocitrate dehydrogenase 1 (IDH1) mutation and O(6)-methylguanine-methyltransferase (MGMT) methylation. To our knowledge, there has been no evaluation in the literature of different proliferation indexes in different GBM locations in the brain. We performed a retrospective evaluation of our prospectively collected database to assess the rate of IDH1 positivity, MGMT methylation and Ki67 index for GBM located in the frontal lobes alone, lobar GBM in other supra-tentorial lobes and multilobar GBM. IDH1 mutated tumors were localized in the frontal lobes in 50.0%, whereas only 20.3% of IDH1 wild-type tumors were localized in the frontal lobe (p=0.006); MGMT methylated tumors were localized in the frontal lobe in 32.0% of the cases. Only 13.75% of the MGMT unmethylated tumors were localized to the frontal lobe (p=0.005); Tumors with higher Ki67 proliferation index were more likely to be localized in the frontal lobe (40.6% vs. 19.5%, p=0.019). This is the largest cohort of GBM assessed for these purposes in the literature. Frontal lobe GBMs may be intrinsically biologically distinct from GBM in other lobes and from multilobar tumors.

Current status of biomarker research in neurology

Neurology is one of the typical disciplines where personalized medicine has been recently becoming an important part of clinical practice. In this article, the brief overview and a number of examples of the use of biomarkers and personalized medicine in neurology are described. The various issues in neurology are described in relation to the personalized medicine and diagnostic, prognostic as well as predictive blood and cerebrospinal fluid biomarkers. Such neurological domains discussed in this work are neuro-oncology and primary brain tumors glioblastoma and oligodendroglioma, cerebrovascular diseases focusing on stroke, neurodegenerative disorders especially Alzheimer's and Parkinson's diseases and demyelinating diseases such as multiple sclerosis. Actual state of the art and future perspectives in diagnostics and personalized treatment in diverse domains of neurology are given.

Prognostic role of IDH mutations in gliomas: a meta-analysis of 55 observational studies

Background

IDH (Isocitrate dehydrogenase) mutations occur frequently in gliomas, but their prognostic impact has not been fully assessed. We performed a meta-analysis of the association between IDH mutations and survival in gliomas.

Methods

Pubmed and EMBASE databases were searched for studies reporting IDH mutations (IHD1/2 and IDH1) and survival in gliomas. The primary outcome was overall survival (OS); the secondary outcome was progression-free survival (PFS). Hazard ratios (HR) with 95% confidence interval (CI) were determined using the Mantel-Haenszel random-effect modeling. Funnel plot and Egger's test were conducted to examine the risk of publication bias.

Results

Fifty-five studies (9487 patients) were included in the analysis. Fifty-four and twenty-seven studies investigated the association between IDH1/2 mutations and OS/PFS respectively in patients with glioma. The results showed that patients possessing an IDH1/2 mutation had significant advantages in OS (HR = 0.39, 95%CI: 0.34–0.45; P < 0.001) and PFS (HR = 0.42, 95% CI: 0.35–0.51; P < 0.001). Subgroup analysis showed a consistent result with pooled analysis, and patients with glioma of WHO grade III or II-III had better outcomes.

Conclusions

These findings provide further indication that patients with glioma harboring IDH mutations have improved OS and PFS, especially for patients with WHO grade III and grade II-III.

Isocitrate Dehydrogenase (IDH)1/2 Mutations as Prognostic Markers in Patients With Glioblastomas

The purpose of this study was to perform a meta-analysis examining the association of isocitrate dehydrogenase (IDH)1/2 mutations with overall survival (OS) and progression-free survival (PFS) in patients with glioblastomas. Medline, Cochrane, EMBASE, and Google Scholar were searched from inception to January 28, 2015, using combinations of the following keywords: IDH mutation, brain tumor, glioma, glioblastoma, oligodendroglioma, prognosis. Randomized controlled trials, and prospective and retrospective studies of patients with glioblastomas that provided IDH mutation and survival data were included. OS and PFS were used to evaluate the association of IDH1 and IDH1/2 mutations and prognosis. Hazard ratios (HRs) with corresponding 95% confidence intervals (CIs) for OS and PFS were calculated and compared between patients with and without mutations. Of 165 studies that were identified, 136 nonrelevant studies were excluded. Twenty-nine full-text articles were assessed, and of these, 5 were excluded as they did not provide a quantitative outcome. Therefore, 24 studies were included in the qualitative synthesis. The pooled HR of 0.358 (95% CI 0.264-0.487, P < 0.001) indicated that IDH mutations were associated with better OS. Similarly, the pooled HR of 0.322 (95% CI 0.24200.455, P < 0.001) indicated that IDH mutations were associated with better PFS. When patients were stratified by surgery versus no surgery or IDH1 versus IDH1/2 mutations, the results also indicated that the presence of IDH mutations was associated with better OS and PFS. The IDH mutations are associated with improved survival in patients with glioblastomas.

IDH1 mutation-associated long non-coding RNA expression profile changes in glioma

Isocitrate dehydrogenase 1 (IDH1) mutation is an important prognostic marker in glioma. However, its downstream effect remains incompletely understood. Long non-coding RNAs (lncRNAs) are emerging as important regulators of tumorigenesis in a number of human malignancies, including glioma. Here, we investigated whether and how lncRNA expression profiles would differ between gliomas with or without IDH1 mutation. By using our previously reported lncRNA mining approach, we performed lncRNA profiling in three public glioma microarray datasets. The differential lncRNA expression analysis was then conducted between mutant-type and wild-type IDH1 glioma samples. Comparison analysis identified 14 and 9 lncRNA probe sets that showed significantly altered expressions in astrocytic and oligodendroglial tumors, respectively (fold change ≥ 1.5, false discovery rate ≤ 0.1). Moreover, the differential expressions of these lncRNAs could be confirmed in the independent testing sets. Functional exploration of the lncRNAs by analyzing the lncRNA-protein interactions revealed that these IDH1 mutation-associated lncRNAs were involved in multiple tumor-associated cellular processes, including metabolism, cell growth and apoptosis. Our data suggest the potential roles of lncRNA in gliomagenesis, and may help to understand the pathogenesis of gliomas associated with IDH1 mutation.

Hypoxia-inducible factor-1 and associated upstream and downstream proteins in the pathophysiology and management of glioblastoma

Glioblastoma multiforme (GBM) is a highly aggressive brain tumor with an exceptionally poor patient outcome despite aggressive therapy including surgery, radiation, and chemotherapy. This aggressive phenotype may be associated with intratumoral hypoxia, which probably plays a key role in GBM tumor growth, development, and angiogenesis. A key regulator of cellular response to hypoxia is the protein hypoxia-inducible factor–1 (HIF-1). An examination of upstream hypoxic and nonhypoxic regulation of HIF-1 as well as a review of the downstream HIF-1– regulated proteins may provide further insight into the role of this transcription factor in GBM pathophysiology. Recent insights into upstream regulators that intimately interact with HIF-1 could provide potential therapeutic targets for treatment of this tumor. The same is potentially true for HIF-1–mediated pathways of glycolysis-, angiogenesis-, and invasion-promoting proteins. Thus, an understanding of the relationship between HIF-1, its upstream protein regulators, and its downstream transcribed genes in GBM pathogenesis could provide future treatment options for the care of patients with these tumors.

Incorporation of biomarkers in phase II studies of recurrent glioblastoma

The survival trends for glioblastoma (GBM) patients have remained largely static, reflecting a lack of improvement in the therapeutic options for patients. Less than 5 % of newly diagnosed GBM survives more than 5 years. Tumor relapse is nearly universal and the majority of patients do not respond to further systemic therapy. The results from phase II studies conducted with recurrent GBM patients have not translated to successful confirmatory studies and thus we have reached a significant roadblock in the development of new treatments for patients with recurrent GBM. The development of new, active, and potentially targeted drugs for the treatment of recurrent GBM represents a major unmet need. The incorporation of diagnostic/companion biomarker combinations into the phase II studies and appropriate stratification of the patients is lagging significantly behind other larger cancer groups such as breast, non-small cell lung cancer, and melanoma. We herein carried out a systematic review of the phase II clinical studies conducted in patients with recurrent GBM (2010-2013 inclusive) to assess the degree of biomarker incorporation within the clinical trial design.