Molecular analysis of anaplastic oligodendroglial tumors in a prospective randomized study: A report from EORTC study 26951

A Custom DNA-Based NGS Panel for the Molecular Characterization of Patients With Diffuse Gliomas: Diagnostic and Therapeutic Applications

The management of patients with Central Nervous System (CNS) malignancies relies on the appropriate classification of these tumors. Recently, the World Health Organization (WHO) has published new criteria underlining the importance of an accurate molecular characterization of CNS malignancies, in order to integrate the information generated by histology. Next generation sequencing (NGS) allows single step sequencing of multiple genes, generating a comprehensive and specific mutational profile of the tumor tissue. We developed a custom NGS-based multi-gene panel (Glio-DNA panel) for the identification of the correct glioma oncotype and the detection of its essential molecular aberrations. Specifically, the Glio-DNA panel targets specific genetic and chromosomal alterations involving ATRX chromatin remodeler (ATRX), cyclin dependent kinase inhibitor 2A (CDKN2A), isocitrate dehydrogenase (NADP+) 1 (IDH1) and the telomerase reverse transcriptase (TERT) promoter while also recognizing the co-deletion of 1p/19q, loss of chromosome 10 and gain of chromosome 7. Furthermore, the Glio-DNA panel also evaluates the methylation level of the O-6-methylguanine-DNA methyltransferase (MGMT) gene promoter that predicts temozolomide efficacy. As knowledge of the mutational landscape of each glioma is mandatory to define a personalized therapeutic strategy, the Glio-DNA panel also identifies alterations involving “druggable” or “actionable” genes. To test the specificity of our panel, we used two reference mutated DNAs verifying that NGS allele frequency measurement was highly accurate and sensitive. Subsequently, we performed a comparative analysis between conventional techniques - such as immunohistochemistry or fluorescence in situ hybridization - and NGS on 60 diffuse glioma samples that had been previously characterized. The comparison between conventional testing and NGS showed high concordance, suggesting that the Glio-DNA panel may replace multiple time-consuming tests. Finally, the identification of alterations involving different actionable genes matches glioma patients with potential targeted therapies available through clinical trials. In conclusion, our analysis demonstrates NGS efficacy in simultaneously detecting different genetic alterations useful for the diagnosis, prognosis and treatment of adult patients with diffuse glioma.

Diagnostic test accuracy and cost-effectiveness of tests for codeletion of chromosomal arms 1p and 19q in people with glioma

BACKGROUND

Complete deletion of both the short arm of chromosome 1 (1p) and the long arm of chromosome 19 (19q), known as 1p/19q codeletion, is a mutation that can occur in gliomas. It occurs in a type of glioma known as oligodendroglioma and its higher grade counterpart known as anaplastic oligodendroglioma. Detection of 1p/19q codeletion in gliomas is important because, together with another mutation in an enzyme known as isocitrate dehydrogenase, it is needed to make the diagnosis of an oligodendroglioma. Presence of 1p/19q codeletion also informs patient prognosis and prediction of the best drug treatment. The main two tests in use are fluorescent in situ hybridisation (FISH) and polymerase chain reaction (PCR)-based loss of heterozygosity (LOH) assays (also known as PCR-based short tandem repeat or microsatellite analysis). Many other tests are available. None of the tests is perfect, although PCR-based LOH is expected to have very high sensitivity.

OBJECTIVES

To estimate the sensitivity and specificity and cost-effectiveness of different deoxyribonucleic acid (DNA)-based techniques for determining 1p/19q codeletion status in glioma.

SEARCH METHODS

We searched MEDLINE, Embase and BIOSIS up to July 2019. There were no restrictions based on language or date of publication. We sought economic evaluation studies from the results of this search and using the National Health Service Economic Evaluation Database.

SELECTION CRITERIA

We included cross-sectional studies in adults with glioma or any subtype of glioma, presenting raw data or cross-tabulations of two or more DNA-based tests for 1p/19q codeletion. We also sought economic evaluations of these tests.

DATA COLLECTION AND ANALYSIS

We followed procedures outlined in the Cochrane Handbook for Diagnostic Test Accuracy Reviews. Two review authors independently screened titles/abstracts/full texts, performed data extraction, and undertook applicability and risk of bias assessments using QUADAS-2. Meta-analyses used the hierarchical summary ROC model to estimate and compare test accuracy. We used FISH and PCR-based LOH as alternate reference standards to examine how tests compared with those in common use, and conducted a latent class analysis comparing FISH and PCR-based LOH. We constructed an economic model to evaluate cost-effectiveness.

MAIN RESULTS

We included 53 studies examining: PCR-based LOH, FISH, single nucleotide polymorphism (SNP) array, next-generation sequencing (NGS), comparative genomic hybridisation (CGH), array comparative genomic hybridisation (aCGH), multiplex-ligation-dependent probe amplification (MLPA), real-time PCR, chromogenic in situ hybridisation (CISH), mass spectrometry (MS), restriction fragment length polymorphism (RFLP) analysis, G-banding, methylation array and NanoString. Risk of bias was low for only one study; most gave us concerns about how patients were selected or about missing data. We had applicability concerns about many of the studies because only patients with specific subtypes of glioma were included. 1520 participants contributed to analyses using FISH as the reference, 1304 participants to analyses involving PCR-based LOH as the reference and 262 participants to analyses of comparisons between methods from studies not including FISH or PCR-based LOH. Most evidence was available for comparison of FISH with PCR-based LOH (15 studies, 915 participants): PCR-based LOH detected 94% of FISH-determined codeletions (95% credible interval (CrI) 83% to 98%) and FISH detected 91% of codeletions determined by PCR-based LOH (CrI 78% to 97%). Of tumours determined not to have a deletion by FISH, 94% (CrI 87% to 98%) had a deletion detected by PCR-based LOH, and of those determined not to have a deletion by PCR-based LOH, 96% (CrI 90% to 99%) had a deletion detected by FISH. The latent class analysis suggested that PCR-based LOH may be slightly more accurate than FISH. Most other techniques appeared to have high sensitivity (i.e. produced few false-negative results) for detection of 1p/19q codeletion when either FISH or PCR-based LOH was considered as the reference standard, although there was limited evidence. There was some indication of differences in specificity (false-positive rate) with some techniques. Both NGS and SNP array had high specificity when considered against FISH as the reference standard (NGS: 6 studies, 243 participants; SNP: 6 studies, 111 participants), although we rated certainty in the evidence as low or very low. NGS and SNP array also had high specificity when PCR-based LOH was considered the reference standard, although with much more uncertainty as these results were based on fewer studies (just one study with 49 participants for NGS and two studies with 33 participants for SNP array). G-banding had low sensitivity and specificity when PCR-based LOH was the reference standard. Although MS had very high sensitivity and specificity when both FISH and PCR-based LOH were considered the reference standard, these results were based on only one study with a small number of participants. Real-time PCR also showed high specificity with FISH as a reference standard, although there were only two studies including 40 participants. We found no relevant economic evaluations. Our economic model using FISH as the reference standard suggested that the resource-optimising test depends on which measure of diagnostic accuracy is most important. With FISH as the reference standard, MLPA is likely to be cost-effective if society was willing to pay GBP 1000 or less for a true positive detected. However, as the value placed on a true positive increased, CISH was most cost-effective. Findings differed when the outcome measure changed to either true negative detected or correct diagnosis. When PCR-based LOH was used as the reference standard, MLPA was likely to be cost-effective for all measures of diagnostic accuracy at lower threshold values for willingness to pay. However, as the threshold values increased, none of the tests were clearly more likely to be considered cost-effective.

AUTHORS' CONCLUSIONS

In our review, most techniques (except G-banding) appeared to have good sensitivity (few false negatives) for detection of 1p/19q codeletions in glioma against both FISH and PCR-based LOH as a reference standard. However, we judged the certainty of the evidence low or very low for all the tests. There are possible differences in specificity, with both NGS and SNP array having high specificity (fewer false positives) for 1p/19q codeletion when considered against FISH as the reference standard. The economic analysis should be interpreted with caution due to the small number of studies.

Shallow whole-genome sequencing: a useful, easy to apply molecular technique for CNA detection on FFPE tumor tissue-a glioma-driven study

Copy number alterations (CNAs) have increasingly become part of the diagnostic algorithm of glial tumors. Alterations such as homozygous deletion of CDKN2A/B, 7 +/ 10 - chromosome copy number changes or EGFR amplification are predictive of a poor prognosis. The codeletion of chromosome arms 1p and 19q, typically associated with oligodendroglioma, implies a more favorable prognosis. Detection of this codeletion by the current diagnostic standard, being fluorescence in situ hybridization (FISH), is sometimes however subject to technical and interpretation problems. In this study, we evaluated CNA detection by shallow whole-genome sequencing (sWGS) as an inexpensive, complementary molecular technique. A cohort of 36 glioma tissue samples, enriched with "difficult" and "ambiguous" cases, was analyzed by sWGS. sWGS results were compared with FISH assays of chromosomes 1p and 19q. In addition, CNAs relevant to glioblastoma diagnosis were explored. In 4/36 samples, EGFR (7p11.2) amplifications and homozygous loss of CDKN2A/B were identified by sWGS. Six out of 8 IDH-wild-type glioblastomas demonstrated a prognostic chromosome 7/chromosome 10 signature. In 11/36 samples, local interstitial and terminal 1p/19q alterations were detected by sWGS, implying that FISH's targeted nature might promote false arm-level extrapolations. In this cohort, differences in overall survival between patients with and without codeletion were better pronounced by the sequencing-based distinction (likelihood ratio of 7.48) in comparison to FISH groupings (likelihood ratio of 0.97 at diagnosis and 1.79 ± 0.62 at reobservation), suggesting sWGS is more accurate than FISH. We recognized adverse effects of tissue block age on FISH signals. In addition, we show how sWGS reveals relevant aberrations beyond the 1p/19q state, such as EGFR amplification, combined gain of chromosome 7 and loss of chromosome 10, and homozygous loss of CDKN2A/B. The findings presented by this study might stimulate implementation of sWGS as a complementary, easy to apply technique for copy number detection.

Comprehensive analysis of genes based on chr1p/19q co-deletion reveals a robust 4-gene prognostic signature for lower grade glioma

Purpose: The chr1p/19q co-deletion is a favorable prognostic factor in patients with lower grade glioma. The aim of this study was to reveal key genes for prognosis and establish prognostic gene signatures based on genes encoded by chr1p/19q. Materials and methods: The data was downloaded from The Cancer Genome Atlas (TCGA), Chinese Glioma Genome Atlas (CGGA) and Gene Expression Omnibus (GEO). Differentially expressed genes (DEGs) between lower grade glioma tissue and normal brain were identified. The univariate COX regression, robust likelihood-base survival analysis (rbsurv) and multivariate COX regression analysis were used to establish the 4-gene-signature based on the DEGs. The receiver operating characteristic (ROC) curve and the Kaplan-Mere curve were used to verify the prediction accuracy of the signature. Gene Set Enrichment Analysis (GSEA) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were also performed to explore the reasons for good prognosis in patients with chr1p/19q deletion. Results: A total of 1346 DEGs were identified between lower grade glioma samples and normal brain samples in GSE16011, including 56 up-regulated mRNAs located on chr1p and 20 up-regulated mRNAs located on chr19q. We established a 4-gene-signature that was significantly associated with survival based on the 76 gene. The AUC of the 4-gene-signature for 5-year OS in TCGA and CGGA was 0.837 and 0.876, respectively, which was superior compared to other parameters such as chr1p/19q co-deletion, IDH mutant, WHO grade and histology type, especially in chr1p/19q non-co-deletion patients. GSEA and KEGG analysis suggested that the prolongation of chr1p/19q in patients could be associated with cell cycle and DNA mismatch repairing. Conclusions: We established a robust 4-gene-signature based on the chr1p/19q and we explored the potential function of these newly identified survival-associated genes by bioinformatics analysis. The 4-gene from the signature are promising molecular targets to be used in the future.

Tumor Necrosis Factor-Alpha (TNF-α-308 G>A) Polymorphism in High-grade Gliomas

BACKGROUND/AIM

High-grade gliomas (HGG) consist of anaplastic oligoastrocytomas, anaplastic oligodendrogliomas, anaplastic astrocytomas and glioblastoma multiforme. The present study aimed to evaluate TNF-α -308 G>A polymorphism in a Turkish population.

PATIENTS AND METHODS

This was a prospective case-control study that included 45 patients with HGG and 49 healthy individuals. All patients were operated for intracranial tumors and the pathology results consist of high grade (Grade3 and 4) glial tumors.

RESULTS

No significant differences were found between the HGG and control groups in terms of the median age (p=0.898). There were no significant differences with regard to gender (p=0.577). The TNF genotype frequency comparison between patients and controls was not statistically significant (p=0.598).

CONCLUSION

TNF genotype frequency comparison between the patients and controls was not statistically significant in the Turkish population tested. However, further studies are needed to evaluate the genotype and phenotype correlations in large cohorts of various ethnicities.

Regional specificity of 1p/19q co-deletion combined with radiological features for predicting the survival outcomes of anaplastic oligodendroglial tumor patients

In this study we aimed to identify the anatomic features of 1p/19q co-deletion and investigate the predictive values of tumor location and radiological characteristics for the survival of anaplastic oligodendroglial (AO) glioma patients. Voxel-based lesion-symptom mapping (VLSM) analysis was applied to define the brain regions associated with occurrence of 1p/19q co-deletion in a cohort of 206 AO tumor patients (discovery set) treated between May 2009 and September 2013. Retrospectively, the acquired clusters and radiological features were subjected to Kaplan-Meier survival analysis using data from the Chinese Glioma Genome Atlas (validation set) to evaluate their prognostic role in AO patients. The institutional review board approved this study. The right frontal lobe and right anterior insular lobe were specifically associated with high occurrence of 1p/19q co-deletion. For AO tumors not involving these areas, the absence of contrast enhancement predicted longer progression-free (p = 0.018) and overall survival (p = 0.020); moreover, in patients with contrast enhancement, edema could stratify the survival outcome (p = 0.013 for progression-free survival, p = 0.016 for overall survival). For AO tumors located in the VLSM-identified regions, edema was also able to stratify the survival outcome of patients without contrast enhancement (p = 0.025 for progression-free survival, p = 0.028 for overall survival). The 1p/19q co-deletion showed predilection for specific brain regions. According to the tumor involvement of VLSM-identified regions associated with 1p/19q co-deletion, radiological features were predictive for AO patient survival outcomes.

Management and treatment recommendations for World Health Organization Grade III and IV gliomas

The treatment recommendations provided in this manuscript are intended to serve as a knowledge base for clinicians and health personals involved in treating patients with high-grade malignant glioma. In newly diagnosed patients, complete resection or biopsy is required for histological characterization of the tumor, which in turn is essential to decide the treatment strategy. In patients with good or borderline performance score, radiotherapy (RT), and chemotherapy are the preferred management. In patients with poor performance score, RT with best possible supportive care is the mainstay of the management. All patients have to undergo brain magnetic resonance imaging procedure quarterly or half-yearly for 5 years and then on an annual basis. In patients with recurrent malignant glioma, wherever possible re-resection or re-irradiation or chemotherapy can be considered along with supportive and palliative care. High-grade malignant glioma should be managed in a multidisciplinary center with the best of the possible care that is available based on the evidence as discussed in this manuscript.

Chromosomal Aberrations in Canine Gliomas Define Candidate Genes and Common Pathways in Dogs and Humans

Spontaneous gliomas in dogs occur at a frequency similar to that in humans and may provide a translational model for therapeutic development and comparative biological investigations. Copy number alterations in 38 canine gliomas, including diffuse astrocytomas, glioblastomas, oligodendrogliomas, and mixed oligoastrocytomas, were defined using an Illumina 170K single nucleotide polymorphism array. Highly recurrent alterations were seen in up to 85% of some tumor types, most notably involving chromosomes 13, 22, and 38, and gliomas clustered into 2 major groups consisting of high-grade IV astrocytomas, or oligodendrogliomas and other tumors. Tumor types were characterized by specific broad and focal chromosomal events including focal loss of the INK4A/B locus in glioblastoma and loss of the RB1 gene and amplification of the PDGFRA gene in oligodendrogliomas. Genes associated with the 3 critical pathways in human high-grade gliomas (TP53, RB1, and RTK/RAS/PI3K) were frequently associated with canine aberrations. Analysis of oligodendrogliomas revealed regions of chromosomal losses syntenic to human 1p involving tumor suppressor genes, such as CDKN2C, as well as genes associated with apoptosis, autophagy, and response to chemotherapy and radiation. Analysis of high frequency chromosomal aberrations with respect to human orthologues may provide insight into both novel and common pathways in gliomagenesis and response to therapy.

Molecular diagnostics: techniques and recommendations for 1p/19q assessment

Several morphology- and polymerase chain reaction (PCR)-based methods for chromosome 1p 19q deletion status assessment are available. Important prerequisites for all molecular techniques concern tissue quality and selection of regions of interest. The most common methods for diagnostic 1p 19q assessment are fluorescence in situ hybridization and PCR-based microsatellite analysis. While the latter requires the use of autologous blood samples, more advanced techniques such as array comparative genomic hybridization, multiplex ligation-dependent probe amplification or real-time PCR are independent from autologous DNA samples. However, due to high technical demand and experience required their applicability as diagnostic tests remains to be shown. On the other hand, chromogenic in situ hybridization evolves as attractive alternative to FISH. Herein, the available test methods are reviewed and outlined, their advantages and drawbacks being discussed in detail.

Prognostic value of epidermal growth factor receptor amplification and EGFRvIII in glioblastoma: meta-analysis

OBJECTIVES

Epidermal growth factor receptor (EGFR) gene amplification and the EGFRvIII mutation may have prognostic value in patients with glioblastoma. This meta-analysis was to determine whether EGFR gene amplification or the EGFRvIII mutation are predictors of survival in patients with glioblastoma and anaplastic astrocytoma.

MATERIALS AND METHODS

Medline, the Cochrane Central Register of Controlled Trials, EMBASE, and Google Scholar databases were searched until July 31, 2014. Studies were selected for inclusion in the analysis if they included patients with anaplastic astrocytoma and/or glioblastoma, EGFR and/or EGFRvIII mutation status was reported, and overall survival (OS) data were reported.

RESULTS

Of 113 articles initially identified, only eight contained data with respect to the outcome of interest and were included in the meta-analysis. The number of cases ranged from 14 to 268, and the majority of patients were 60 or more years of age. There was no significant difference in OS between EGFR amplification-positive and EGFR amplification-negative glioblastoma patients (pooled hazard ratio [HR] = 1.101, 95% confidence interval [CI] 0.845, 1.434, P = 0.475) or anaplastic astrocytoma patients (pooled HR = 1.455, 95% CI 0.852, 2.482, P = 0.169). There was no significant difference in OS between EGFRvIII-positive and EGFRvIII-negative glioblastoma patients (pooled HR = 1.321, 95% CI: 0.881-1.981, P = 0.178). Significant heterogeneity existed between the studies, and the significance changed when the analysis was performed with studies removed in turn.

CONCLUSIONS

There is insufficient evidence that either EGFR amplification or the EGFRvIII mutation has prognostic value in patients with glioblastoma.

Molecular classification of anaplastic oligodendroglioma using next-generation sequencing: a report of the prospective randomized EORTC Brain Tumor Group 26951 phase III trial

BACKGROUND

Histopathological diagnosis of diffuse gliomas is subject to interobserver variation and correlates modestly with major prognostic and predictive molecular abnormalities. We investigated a series of patients with locally diagnosed anaplastic oligodendroglial tumors included in the EORTC phase III trial 26951 on procarbazine/lomustine/vincristine (PCV) chemotherapy to explore the diagnostic, prognostic, and predictive value of targeted next-generation sequencing (NGS) in diffuse glioma and to assess the prognostic impact of FUBP1 and CIC mutations.

METHODS

Mostly formalin-fixed paraffin-embedded samples were tested with targeted NGS for mutations in ATRX, TP53, IDH1, IDH2, CIC, FUBP1, PI3KC, TERT, EGFR, H3F3A, BRAF, PTEN, and NOTCH and for copy number alterations of chromosomes 1p, 19q, 10q, and 7. TERT mutations were also assessed, with PCR.

RESULTS

Material was available from 139 cases, in 6 of which results were uninformative. One hundred twenty-six tumors could be classified: 20 as type II (IDH mutation [mut], "astrocytoma"), 49 as type I (1p/19q codeletion, "oligodendroglioma"), 55 as type III (7+/10q- or TERTmut and 1p/19q intact, "glioblastoma"), and 2 as childhood glioblastoma (H3F3Amut), leaving 7 unclassified (total 91% classified). Molecular classification was of clear prognostic significance and correlated better with outcome than did classical histopathology. In 1p/19q codeleted tumors, outcome was not affected by CIC and FUBP1 mutations. MGMT promoter methylation remained the most predictive factor for survival benefit of PCV chemotherapy.

CONCLUSION

Targeted NGS allows a clinically relevant classification of diffuse glioma into groups with very different outcomes. The diagnosis of diffuse glioma should be primarily based on a molecular classification, with the histopathological grade added to it. Future discussion should primarily aim at establishing the minimum requirements for molecular classification of diffuse glioma.

Impact of oligodendroglial component in glioblastoma (GBM-O): Is the outcome favourable than glioblastoma?

BACKGROUND

Prognosis of patients with glioblastoma with oligodendroglial component (GBM-O) is not well defined. We report our experience of patients of GBM-O treated at our center.

METHODS

Between January 2007 and August 2013, out of 817 consecutive patients with glioblastoma (GBM), 74 patients with GBM-O were identified in our prospectively maintained database. An experienced neuropathologist revaluated the histopathology of all these 74 patients and the diagnosis of GBM-O was eventually confirmed in 57 patients. Patients were uniformly treated with maximal safe resection followed by focal radiotherapy with concurrent and adjuvant temozolamide (TMZ).

RESULTS

At a median follow up of 16 months, median overall survival (OS) and progression free survival (PFS) of the entire cohort was 23 months and 13 months respectively. Near total excision was performed in 30/57 (52.6%). On univariate analysis, age < 50 years was a significant favourable prognostic factor for OS (p = 0.009) and PFS (p = 0.017), while patients with near total resection had a significantly better PFS (p = 0.017), patients who completed a minimum of 6 cycles of adjuvant TMZ had significantly better OS (p = 0.000) and PFS (p = 0.003). On multivariate analysis, none of the above factors were significant except for patient who had completed a minimum of 6 cycles of TMZ (OS; p = 0.000 & PFS; p = 0.015). A comparative analysis of GBM-O patients with a similarly treated cohort of 105 GBM patients during the same period revealed significantly better median OS in favour of GBM-O (p = 0.01).

CONCLUSIONS

Our experience suggests patients with GBM-O have a more favourable clinical outcome as compared to GBM.

Evidence-Based Diagnostic Algorithm for Glioma: Analysis of the Results of Pathology Panel Review and Molecular Parameters of EORTC 26951 and 26882 Trials

PURPOSE

With the rapid discovery of prognostic and predictive molecular parameters for glioma, the status of histopathology in the diagnostic process should be scrutinized. Our project aimed to construct a diagnostic algorithm for gliomas based on molecular and histologic parameters with independent prognostic values.

METHODS

The pathology slides of 636 patients with gliomas who had been included in EORTC 26951 and 26882 trials were reviewed using virtual microscopy by a panel of six neuropathologists who independently scored 18 histologic features and provided an overall diagnosis. The molecular data for IDH1, 1p/19q loss, EGFR amplification, loss of chromosome 10 and chromosome arm 10q, gain of chromosome 7, and hypermethylation of the promoter of MGMT were available for some of the cases. The slides were divided in discovery (n = 426) and validation sets (n = 210). The diagnostic algorithm resulting from analysis of the discovery set was validated in the latter.

RESULTS

In 66% of cases, consensus of overall diagnosis was present. A diagnostic algorithm consisting of two molecular markers and one consensus histologic feature was created by conditional inference tree analysis. The order of prognostic significance was: 1p/19q loss, EGFR amplification, and astrocytic morphology, which resulted in the identification of four diagnostic nodes. Validation of the nodes in the validation set confirmed the prognostic value (P < .001).

CONCLUSION

We succeeded in the creation of a timely diagnostic algorithm for anaplastic glioma based on multivariable analysis of consensus histopathology and molecular parameters.

Efficacy and patient-reported outcomes with dose-intense temozolomide in patients with newly diagnosed pure and mixed anaplastic oligodendroglioma: a phase II multicenter study

Standard initial therapy for patients with pure and mixed anaplastic oligodendrogliomas (AO/MAO) includes chemotherapy and radiation therapy. Anaplastic oligodendrogliomas with 1p/19q co-deletion are more responsive to chemotherapy. There is concern for potential long-term CNS toxicity of radiation. Hence an approach using chemotherapy initially and reserving radiation for progressive disease is attractive. This multicenter phase II trial included patients with newly diagnosed AO/MAO with central pathology review and 1p/19q assay. Temozolomide was given 150 mg/m(2) days 1-7 and 15-21, every 28 days for 8 cycles. The primary endpoint was progression free survival (PFS). Secondary endpoints included response rate, overall survival (OS), treatment toxicity and health-related quality of life (HRQL). Data from 62 patients enrolled between December 2001 and April 2007 at seven centers were analyzed. Among patients with measurable disease, 8 % achieved complete remission, 56 % had stable disease and 36 % had progression. The median PFS and OS were 27.2 months (95 % CI 11.9-36.3) and 105.8 months (95 % CI 51.5-N/A), respectively. Both 1p loss and 1p/19q co-deletion were positive prognostic factors for PFS (p < 0.001) and OS (p < 0.001); and there was some suggestion that 1p/19q co-deletion also predicted better response to chemotherapy (p = 0.007). Grade 3/4 toxicities were mainly hematological. Significantly improved HRQL in the future uncertainty domain of the brain cancer module was seen after cycle 4 (p < 0.001). This trial achieved outcomes similar to those reported previously. Toxicities from dose-intense temozolomide were manageable. Improvement in at least one HRQL domain increased over time. This trial supports the further study of first-line temozolomide monotherapy as an alternative to radiation therapy for patients with newly diagnosed AO/MAO with 1p 19q co-deleted tumors.

Medical therapy of gliomas

Medical therapies are an important part of adjunctive therapy for gliomas. In this chapter we will review the chemotherapeutic and targeted agents that have been evaluated in clinical trials in grade II-IV gliomas in the last decade. A number of randomized phase III trials were completed and reported. There has been a clear success in oligodendroglial tumors and low grade glioma. Although some progress has been made in glioblastoma, considerable work involving the multidisciplinary collaboration of basic science, translational and clinical investigators needs to be done to improve the outcome of patients with anaplastic astrocytoma and glioblastoma. In addition, tailoring treatment based on molecular cytogenetic characteristics is a major focus of research into precision based medicine for glioma.

Adjuvant treatment of anaplastic oligodendrogliomas and oligoastrocytomas

BACKGROUND

Standard care of adjuvant treatment for anaplastic oligodendrogliomas (AO) and anaplastic oligoastrocytomas (AOA) is not yet well defined. The benefit of adjuvant chemotherapy and radiotherapy (RT), given as single modalities or sequentially, is still unclear. Furthermore, insight into the predictive and prognostic impact of various biomarkers is surging.

OBJECTIVES

To compare postoperative sequential RT and chemotherapy to RT alone in adults with newly diagnosed AO or mixed AOA. To evaluate the predictive and prognostic impact of the following biomarkers: codeletion of chromosomes 1p and 19q, O(6)-methylguanine-DNA methyltransferase (MGMT) promotor methylation and isocitrate dehydrogenase (IDH)-1 and -2 mutations.

SEARCH METHODS

We searched the Cochrane Central Register for Controlled Trials (CENTRAL, Issue 1, 2014), MEDLINE (2006 to March week 2, 2014) and EMBASE (2006 to week 11, 2014). We scanned reference lists from relevant studies for any additional articles.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) of adults with AO, AOA or anaplastic astrocytoma (AA) comparing adjuvant treatment of chemotherapy, RT, or sequential chemotherapy and RT. We excluded no specific chemotherapy regimens.

DATA COLLECTION AND ANALYSIS

We critically appraised and extracted data from relevant studies. Based on the differences in participant selection with respect to the definition of AO (two versus three high-risk anaplastic features), the inclusion of AA and sequence of treatment (RT and chemotherapy), we could not consider the results from the three RCTs for meta-analysis.

MAIN RESULTS

Three RCTs, with 931 participants, tested different neoadjuvant treatments: RT alone; sequential RT and procarbazine, lomustine and vincristine (PCV) chemotherapy; PCV chemotherapy alone; and temozolomide chemotherapy alone. None of the studies blinded participants or personnel, and, therefore, are considered at high risk of performance and detection bias. The studies were otherwise at low risk of bias. One study, the European Organisation for Research and Treatment of Cancer (EORTC) trial, demonstrated a statistically significant overall survival (OS) benefit for RT plus PCV, with a median OS of 3.5 years compared with 2.6 years in the RT alone arm (P value = 0.018). This result was reported 10 years after the conclusion of the enrolment, and was not apparent in the original 2008 Cochrane review. Furthermore, with retrospective evaluation of biomarkers, codeletion of complete chromosome arms 1p and 19q and IDH-1 or -2 mutation were independent prognostic factors for OS in two of the RCTs (Radiation Therapy Oncology Group (RTOG) and EORTC), and were predictive for OS in one trial (RTOG). The third trial (NOA-04) evaluated these biomarkers prospectively and found them prognostic for progression-free survival.

AUTHORS' CONCLUSIONS

Early PCV, either before or after RT, appears to improve OS of participants with AO or AOA. Use of biomarkers including codeletion of chromosomes 1p and 19q with or without IDH-1 or -2 mutation identify a subset of people with increased sensitivity to combined PCV and RT. The important role of biomarkers was supported in all of the RCTs examined, and prospective evaluation should be undertaken in future studies. However, PCV was associated with significant grade 3 and 4 toxicities, and whether temozolomide can be substituted for this remains unclear.

Polymorphous oligodendroglioma of Zülch revisited: a genetically heterogeneous group of anaplastic gliomas including tumors of bona fide oligodendroglial differentiation

A polymorphous variant of oligodendroglioma was described by K.J. Zülch half a century ago, and is only very sporadically referred to in the subsequent literature. In particular, no comprehensive analysis with respect to clinical or genetic features of these tumors is available. From a current perspective, the term polymorphous oligodendroglioma (pO) may appear as contradictory in terms, as nuclear monotony is a histomorphological hallmark of oligodendrogliomas. For the purpose of this study, we defined pO as diffusely infiltrating gliomas felt to be of oligodendroglial rather than astrocytic differentiation and characterized by the presence of multinucleate tumor giant cells and/or nuclear pleomorphism. In a total of nine patients, we identified tumors consistent with this working definition. All tumors were high-grade. We characterized these with respect to clinical, histomorphological and genetic features. Despite clinical and genetic heterogeneity, we identified a subset of tumors of bona fide oligodendroglial differentiation as characterized by combined loss of heterozygosity of chromosome arms 1p and 19q (LOH 1p19q). Those tumors that lacked LOH 1p19q showed a high frequency of IDH1 mutations and loss of alpha thalassemia/mental retardation syndrome X-linked gene (ATRX) immunoreactivity, indicating a possible phenotypic convergence of true oligodendrogliomas and gliomas of the alternative lengthening of telomeres (ALT) pathway. p53 alterations were common irrespective of the 1p19q status. Histomorphologically, the tumors featured interspersed bizarre multinucleate giant tumor cells, while the background population varied from monotonous to significantly pleomorphic. Our findings indicate, that a rare polymorphous - or "giant cell" - variant of oligodendroglioma does indeed exist.

1p/19q testing has no significance in the workup of glioblastomas

AIMS

To determine whether testing for isolated 1p or 19q losses, or as a codeletion, has any significance in the workup of glioblastomas (GBMs).

METHODS

Upfront 1p/19q testing by fluorescence in situ hybridization (FISH) and/or polymerase chain reaction (PCR)-based loss of heterozygosity (LOH) was done in 491 gliomas that were histologically diagnosed as GBMs. Outcomes were determined and measured against 1p/19q results.

RESULTS

Twenty-eight showed apparent 1p/19q codeletion by either FISH and/or PCR-based LOH, but only 1/26 showed codeletion by both tests. Over 90% of tumours with apparent codeletion by either FISH or LOH also had 10q LOH and/or EGFR amplification, features inversely related to true whole-arm 1p/19q codeletion. Furthermore, only 1/28 tumours demonstrated an R132H IDH1 mutation. Neither 1p/19q codeletion by FISH nor LOH had an impact on GBM survival. Isolated losses of 1p or 19q also had no impact on survival.

CONCLUSIONS

These data suggest that (i) 1p/19q testing is not useful on gliomas that are histologically GBMs; (ii) codeletion testing should be reserved only for cases with compatible morphology; and (iii) EGFR, 10q, and IDH1 testing can help act as safeguards against a false-positive 1p/19q result.

MGMT-STP27 methylation status as predictive marker for response to PCV in anaplastic Oligodendrogliomas and Oligoastrocytomas. A report from EORTC study 26951

PURPOSE

The long-term follow-up results from the EORTC-26951 trial showed that the addition of procarbazine, CCNU, and vincristine (PCV) after radiotherapy increases survival in anaplastic oligodendrogliomas/oligoastrocytomas (AOD/AOA). However, some patients appeared to benefit more from PCV treatment than others.

EXPERIMENTAL DESIGN

We conducted genome-wide methylation profiling of 115 samples included in the EORTC-26951 trial and extracted the CpG island hypermethylated phenotype (CIMP) and MGMT promoter methylation (MGMT-STP27) status.

RESULTS

We first show that methylation profiling can be conducted on archival tissues with a performance that is similar to snap-frozen tissue samples. We then conducted methylation profiling on EORTC-26951 clinical trial samples. Univariate analysis indicated that CIMP+ or MGMT-STP27 methylated tumors had an improved survival compared with CIMP- and/or MGMT-STP27 unmethylated tumors [median overall survival (OS), 1.05 vs. 6.46 years and 1.06 vs. 3.8 years, both P < 0.0001 for CIMP and MGMT-STP27 status, respectively]. Multivariable analysis indicates that CIMP and MGMT-STP27 are significant prognostic factors for survival in presence of age, sex, performance score, and review diagnosis in the model. CIMP+ and MGMT-STP27 methylated tumors showed a clear benefit from adjuvant PCV chemotherapy: the median OS of CIMP+ samples in the RT and RT-PCV arms was 3.27 and 9.51 years, respectively (P = 0.0033); for MGMT-STP27 methylated samples, it was 1.98 and 8.65 years. There was no such benefit for CIMP- or for MGMT-STP27 unmethylated tumors. MGMT-STP27 status remained significant in an interaction test (P = 0.003). Statistical analysis of microarray (SAM) identified 259 novel CpGs associated with treatment response.

CONCLUSIONS

MGMT-STP27 may be used to guide treatment decisions in this tumor type.

Molecular predictors of outcome in low-grade glioma

PURPOSE OF REVIEW

Recent and ongoing translational studies in neurooncology have investigated the role of molecular markers as potential predictors of outcome in patients with WHO grade I and II gliomas, commonly summarized as low-grade gliomas (LGGs). Here, we seek to highlight the most relevant molecular aberrations associated with these tumour types and update on recent findings on their potential prognostic and predictive value.

RECENT FINDINGS

So far, no biomarker discussed has any relevance for the postoperative course of disease without genotoxic treatment. Isocitrate dehydrogenase (IDH) mutations, 1p deletion or 1p/19q codeletion have the strongest prognostic impact on survival of patients with LGG, given a genotoxic treatment is provided. Recent findings from phase III clinical trials on anaplastic oligodendroglial tumours conducted in North America and Europe suggest that the addition of procarbazine, lomustine and vincristine to radiotherapy is beneficial in the treatment of anaplastic gliomas with 1p/19q codeletion. To decipher the role of 1p/19q codeletion in LGG will be challenging. Recent developments in v-raf murine sarcoma viral oncogene homolog B1 (BRAF)(V600E)-specific small molecule inhibitors and their clinical approval for other cancer types could turn BRAF(V600E) into a promising molecular predictor of outcome in pilocytic astrocytomas, given a treatment with a mutation-specific BRAF inhibitor is applied.

SUMMARY

Clinical prognostic factors such as age, tumour size and the presence or absence of clinical symptoms have long been recognized in the management of patients with LGGs. Molecular biomarkers are increasingly evolving as additional factors that facilitate diagnostics and therapeutic decision-making. However, further prospective randomized studies including multivariate analyses are needed to clearly distinguish between prognostic and predictive effects.

Oligodendrogliomas: new insights from the genetics and perspectives

PURPOSE OF REVIEW

Since the discovery, in 1994, of recurrent codeletion of chromosome regions 1p36/19q13 in oligodendrogliomas, genetics has accomplished significant advances improving our knowledge in biology of this tumor type and our clinical management of oligodendroglioma patients. Indeed, 1p36/19q13 has been shown successively to predict increased chemosensitivity and better prognosis, to be associated with frontal location in brain and classic oligodendroglioma morphology, to be mutually exclusive with high-level gene amplification, to be actually whole chromosome arms 1p/19q codeletion, to mediate a t(1;19)(q10;p10) and to be associated with IDH mutations. More recently, pivotal studies, using high-throughput approaches, have provided significant novel insights in the molecular oncogenesis of oligodendrogliomas.

RECENT FINDINGS

Capicua homolog (Drosophila) (CIC) and Far Upstream element Binding Protein 1 (FUBP1) have been shown to be frequently mutated in 70 and 40% of 1p/19q codeleted oligodendrogliomas, respectively. The biological and clinical significance of these mutations remains unsettled. Additional recent studies have also demonstrated that 1p/19q codeleted oligodendrogliomas exhibit a proneural transcriptomic profile including overexpression of internexin alpha, a neuronal intermediate filament. Finally, 1p/19q codeleted and IDH-mutated tumors have been shown to be hypermethylated, suggesting a strong link between these both molecular alterations detected in the subgroup of oligodendrogliomas with better prognosis.

SUMMARY

Next-generation molecular biology technologies have recently identified recurrent CIC and FUBP1 point mutations in 1p/19q codeleted and IDH-mutated oligodendrogliomas. Their clinical and biological values are under investigation.

Understanding high grade glioma: molecular mechanism, therapy and comprehensive management

High-grade gliomas (HGGs) account for the vast majority of all gliomas, including glioblastoma (World Health Organization (WHO) grade IV) and anaplasticgliomas (WHO grade III). Despite tremendous efforts in developing multimodal treatments, the overall prognosis remains poor; however, survival time varies considerably between patients. The nature of diffuse permeation into surrounding brain parenchyma poses dilemma for neurosurgeons between extensive surgical resection to eliminate as much as tumor cells as possible and adverse effects associated with brain function. Heterogeneity in both cytology and gene expression makes it difficult to coordinate an effective therapy which works for every patient. This article reviews recent advancements in the molecular mechanism, multimodal treatment and clinical management, and the updated view on the biomarkers in patients with HGG, both in primary and recurrent setting, with an emphasis on targeted therapies tailored to the patient.

Adjuvant Procarbazine, Lomustine, and Vincristine Chemotherapy in Newly Diagnosed Anaplastic Oligodendroglioma: Long-Term Follow-Up of EORTC Brain Tumor Group Study 26951

Purpose

Anaplastic oligodendroglioma are chemotherapy-sensitive tumors. We now present the long-term follow-up findings of a randomized phase III study on the addition of six cycles of procarbazine, lomustine, and vincristine (PCV) chemotherapy to radiotherapy (RT).

Patients and Methods

Adult patients with newly diagnosed anaplastic oligodendroglial tumors were randomly assigned to either 59.4 Gy of RT or the same RT followed by six cycles of adjuvant PCV. An exploratory analysis of the correlation between 1p/19q status and survival was part of the study. Retrospectively, the methylation status of the methyl-guanine methyl transferase gene promoter and the mutational status of the isocitrate dehydrogenase (IDH) gene were determined. The primary end points were overall survival (OS) and progression-free survival based on intent-to-treat analysis.

Results

A total of 368 patients were enrolled. With a median follow-up of 140 months, OS in the RT/PCV arm was significantly longer (42.3 v 30.6 months in the RT arm, hazard ratio [HR], 0.75; 95% CI, 0.60 to 0.95). In the 80 patients with a 1p/19q codeletion, OS was increased, with a trend toward more benefit from adjuvant PCV (OS not reached in the RT/PCV group v 112 months in the RT group; HR, 0.56; 95% CI, 0.31 to 1.03). IDH mutational status was also of prognostic significance.

Conclusion

The addition of six cycles of PCV after 59.4 Gy of RT increases both OS and PFS in anaplastic oligodendroglial tumors. 1p/19q-codeleted tumors derive more benefit from adjuvant PCV compared with non–1p/19q-deleted tumors.

Intrinsic molecular subtypes of glioma are prognostic and predict benefit from adjuvant procarbazine, lomustine, and vincristine chemotherapy in combination with other prognostic factors in anaplastic oligodendroglial brain tumors: a report from EORTC study 26951

PURPOSE

Intrinsic glioma subtypes (IGSs) are molecularly similar tumors that can be identified based on unsupervised gene expression analysis. Here, we have evaluated the clinical relevance of these subtypes within European Organisation for Research and Treatment of Cancer (EORTC) 26951, a randomized phase III clinical trial investigating adjuvant procarbazine, lomustine, and vincristine (PCV) chemotherapy in anaplastic oligodendroglial tumors. Our study includes gene expression profiles of formalin-fixed, paraffin-embedded (FFPE) clinical trial samples.

PATIENTS AND METHODS

Gene expression profiling was performed in 140 samples, 47 fresh frozen samples and 93 FFPE samples, on HU133_Plus_2.0 and HuEx_1.0_st arrays, respectively.

RESULTS

All previously identified six IGSs are present in EORTC 26951. This confirms that different molecular subtypes are present within a well-defined histologic subtype. Intrinsic subtypes are highly prognostic for overall survival (OS) and progression-free survival (PFS). They are prognostic for PFS independent of clinical (age, performance status, and tumor location), molecular (1p/19q loss of heterozygosity [LOH], IDH1 mutation, and MGMT methylation), and histologic parameters. Combining known molecular (1p/19q LOH, IDH1) prognostic parameters with intrinsic subtypes improves outcome prediction (proportion of explained variation, 30% v 23% for each individual group of factors). Specific genetic changes (IDH1, 1p/19q LOH, and EGFR amplification) segregate into different subtypes. We identified one subtype, IGS-9 (characterized by a high percentage of 1p/19q LOH and IDH1 mutations), that especially benefits from PCV chemotherapy. Median OS in this subtype was 5.5 years after radiotherapy (RT) alone versus 12.8 years after RT/PCV (P = .0349; hazard ratio, 2.18; 95% CI, 1.06 to 4.50).

CONCLUSION

Intrinsic subtypes are highly prognostic in EORTC 26951 and improve outcome prediction when combined with other prognostic factors. Tumors assigned to IGS-9 benefit from adjuvant PCV.

Something old and something new about molecular diagnostics in gliomas

Progress in our understanding of the molecular biology of neoplasms has been driven by remarkable improvements in molecular biology techniques. This has created a rapidly moving field in which even subspecialists struggle to keep abreast of the current literature. Nowhere is this more clearly demonstrated than in neuro-oncology, wherein molecular diagnostics can now wring more clinically useful information out of very small biopsies than ever before. Herein the biologic and practical aspects of four key molecular biomarkers in gliomas are discussed, including two that have been known for some time (1p/19q codeletion and EGFR amplification) as well as two whose relevance was discovered via advanced whole-genome assays (IDH1/2 mutations and BRAF alterations).

Hypoxia-inducible factor-1-regulated protein expression and oligodendroglioma patient outcome: comparison with established biomarkers and preoperative UCSF low-grade scoring system

Methods for predicting outcome for patients with oligodendrogliomas and anaplastic oligodendrogliomas (AOs) are limited. Hypoxia-inducible factor-1α (HIF-1α) controls many proteins involved in glycolysis and angiogenesis including VEGF, Glut-1, and CA-IX. We examined whether expression of HIF-1α and other hypoxia-regulated molecules (HRM) can predict overall (OS) and progression-free (PFS) survival. We correlated these data with more established biomarkers and a published preoperative scoring system. We prospectively collected tissue samples and followed outcomes of 50 patients with oligodendrogliomas and 32 with AOs. Tumor tissues were stained for measures of proliferative index, microvascular density, IDH-1 mutational status, and HRMs. We retrospectively analyzed preoperative imaging and clinical data based on the UCSF Scoring System (good prognostic indicators: Karnofsky Performance Scale (KPS) score > 80, age < 50 years, tumor diameter < 4 cm, noneloquent tumor location) and correlated these with immunohistochemical markers, 1p19q chromosomal status, and compared both with patient PFS and OS. Mean follow-up was 85.6 ± 41.4 months. HRMs showed higher expression in AOs than in oligodendrogliomas. Both 1p19q codeletion and IDH-1 mutation predict outcome of patients with both oligodendroglioma and AO. The UCSF score is a strong predictor for oligodendrogliomas patient outcome and is strengthened by IDH-1 and 1p19q status. Glut-1 may be useful in predicting PFS in AOs. Proliferation index >5 for oligodendrogliomas and KPS ≤ 80 for AOs predict a worse prognosis. Immunohistochemical markers of HRMs show a significantly higher expression in anaplastic variants of oligodendrogliomas and may contribute to the prediction of survival in these patients.

Prognostic value of Ki67 index in anaplastic oligodendroglial tumours--a translational study of the European Organization for Research and Treatment of Cancer Brain Tumor Group

AIMS

To evaluate the prognostic value and clinical utility of Ki67 tumour cell proliferation index in anaplastic oligodendroglial tumours (AOT).

METHODS AND RESULTS

We performed anti-Ki67 immunostaining (MIB-1 antibody) of formalin-fixed and paraffin-embedded tumour tissue specimens of 128 patients with newly diagnosed AOT that were treated in a randomized Phase III trial. Ki67 index was assessed by three independent observers and was correlated to clinical, histopathological and molecular features (including 1p/19q co-deletion, epithelial growth factor receptor gene (EGFR) amplification, isocitrate dehydrogenase (IDH1) mutations, O6-methylguanine-DNA methyltransferase gene (MGMT) promoter methylation, and patient survival times. Intra- and inter-observer agreement of Ki67 index assessment was excellent. Univariable analysis (n = 79) showed that patients with a low Ki67 index had significantly more favourable progression-free survival (PFS) (P-value = 0.004, log-rank test) and overall survival (OS) (P-value = 0.003, log-rank test) than patients with a high Ki67 index, respectively. On multivariable analysis (n = 43), Ki67 index showed no independent association with PFS or OS.

CONCLUSIONS

In AOT the Ki67 index has a strong prognostic impact on univariable analysis, but no independent influence on multivariable analysis. However, further prospective studies including larger numbers of cases and standardized evaluation of Ki67 index in conjunction with other relevant prognostic parameters are needed to draw definitive conclusions.

The importance of 10q status in an outcomes-based comparison between 1p/19q fluorescence in situ hybridization and polymerase chain reaction-based microsatellite loss of heterozygosity analysis of oligodendrogliomas

1p/19q codeletion is a favorable prognostic marker of oligodendrogliomas. Although fluorescence in situ hybridization (FISH) and microsatellite-based polymerase chain reaction (PCR) for loss of heterozygosity (LOH) are common methods to test for 1p/19q codeletion, it is unclear which test is better at prognostic stratification. This study analyzed outcomes of 111 oligodendrogliomas with both 1p/19q FISH and LOH done at the time of diagnosis. Overall concordance between the 2 assays was 81.1%. In grade III oligodendrogliomas, LOH was better than FISH at survival stratification (p < 0.0001 for LOH vs p = 0.02 for FISH), although increasing the stringency of FISH interpretation criteria improved concordance and prognostic power. Oligodendrogliomas that were 1p/19q-codeleted by FISH but also had 10q LOH were negative for 1p/19q codeletion by PCR analysis in more than 70% of cases, with very poor survival in the grade III subset. Thus, although PCR-based LOH is a better stratifier of 1p/19q status, FISH still has clinical and prognostic utility, especially if 10q data can be incorporated.

Glioblastoma with an oligodendroglioma component: distinct clinical behavior, genetic alterations, and outcome

Glioblastomas (GBMs) containing foci that resemble oligodendroglioma are defined as GBM with oligodendroglioma component (GBMO). However, whether GBMO is a distinct clinicopathological variant of GBM or merely represents a divergent pattern of differentiation remains controversial. We investigated 219 consecutive primary GBMs, of which 40 (18.3%) were confirmed as GBMOs. The clinical features and genetic profiles of the GBMOs were analyzed and compared with the conventional GBMs. The GBMO group showed more frequent tumor-related seizures (P= .027), higher frequency of IDH1 mutation (31% vs. <5%, P= .015), lower MGMT expression (P= .016), and longer survival (19.0 vs. 13.2 months; P= .022). In multivariate Cox regression analyses, presence of an oligodendroglioma component was predictive of longer survival (P= .001), but the extent of the oligodendroglial component appeared not to be linked to prognosis (P= .664). The codeletions of 1p/19q, somewhat surprisingly, were infrequent (<5%) in both GBMO and conventional GBM. In addition, the response to aggressive therapy differed: the GBMO group had no survival advantage associated with aggressive treatment protocols, whereas a clear treatment effect was observed in the conventional GBM group. Collectively, the clinical behavior and genetic alterations of GBMO thus differs from those of conventional GBM. Presence of an oligodendroglial component may therefore be a useful classification and stratification variable in therapeutic trials of GBMs.

Molecular prognostic factors of anaplastic oligodendroglial tumors and its relationship: a single institutional review of 77 patients from China

The increased chemosensitivity of oligodendroglial tumors has been associated with loss of heterozygosity (LOH) on chromosomes 1p and 19q. Other clinical and molecular factors have also been identified as being prognostic and predictive for treatment outcome. Seventy-seven patients with anaplastic oligodendroglioma (AO) or anaplastic oligoastrocytoma (AOA), treated in Beijing Tiantan Hospital from 2006 through 2008, were reviewed. LOH 1p, LOH 19q, IDH1 mutation, O(6)-methylguanine-DNA methyltransferase (MGMT) promoter methylation, and protein expression level of MGMT, P53, EGFR, and Ki-67 were evaluated. Age at diagnosis, LOH 1p and 19q, IDH1 mutation, P53 expression level, reoperation when progression, and adjuvant chemotherapy were statistically significant factors for overall survival (OS) in univariate analysis. Further multivariate analysis showed that age at diagnosis (P = .010), LOH 1p and 19q (P = .016), IDH1 mutation (P = .011), and reoperation after progression (P = .048) were independent predictors for longer survival in these patients. Nonrandom associations were found between LOH 1p and LOH 19q, MGMT promoter methylation and LOH 1p or 19q, IDH1 mutation and LOH 1p and 19q, IDH1 mutation and MGMT promoter methylation, whereas mutual exclusion was found between MGMT promoter methylation and MGMT expression level. The present study confirmed that age at diagnosis, LOH 1p and 19q, IDH1 mutation, and reoperation after progression were independent significant prognostic factors for patients with anaplastic oligodendroglial tumors. Inter-relationship between LOH 1p, LOH 19q, IDH1 mutation, MGMT promoter methylation, and MGMT expression level were also revealed. Future clinical trials for AO and AOA should consider the molecular alterations of patients.

A hypermethylated phenotype is a better predictor of survival than MGMT methylation in anaplastic oligodendroglial brain tumors: a report from EORTC study 26951

PURPOSE

The MGMT promoter methylation status has been suggested to be predictive for outcome to temozolomide chemotherapy in patients with glioblastoma (GBM). Subsequent studies indicated that MGMT promoter methylation is a prognostic marker even in patients treated with radiotherapy alone, both in GBMs and in grade III gliomas.

EXPERIMENTAL DESIGN

To help determine the molecular mechanism behind this prognostic effect, we have conducted genome-wide methylation profiling and determined the MGMT promoter methylation status, 1p19q LOH, IDH1 mutation status, and expression profile on a series of oligodendroglial tumors [anaplastic oligodendrogliomas (AOD) and anaplastic oligoastrocytomas (AOA)] within EORTC study 26951. The series was expanded with tumors of the same histology and treatment from our own archive.

RESULTS

Methylation profiling identified two main subgroups of oligodendroglial brain tumors of which survival in the CpG island hypermethylation phenotype (CIMP(+)) subgroup was markedly better than the survival of the unmethylated (CIMP(-)) subgroup (5.62 vs. 1.24 years; P < 0.0001). CIMP status correlated with survival, MGMT promoter methylation, 1p19q LOH, and IDH1 mutation status. CIMP status strongly increases the predictive accuracy of survival in a model including known clinical prognostic factors such as age and performance score. We validated our results on an independent data set from the Cancer Genome Atlas (TCGA).

CONCLUSION

The strong association between CIMP status and MGMT promoter methylation suggests that the MGMT promoter methylation status is part of a more general, prognostically favorable genome-wide methylation profile. Methylation profiling therefore may help identify AODs and AOAs with improved prognosis.

EGFR expression stratifies oligodendroglioma behavior

Epidermal growth factor receptor (EGFR) expression and signaling contribute to glioma biological features and, thus, are a target for new drug development. The role, if any, of EGFR in routine surgical neuropathological diagnostics is less clear. Herein, we describe prospective EGFR IHC analysis in an adult cohort comprising 750 infiltrative gliomas. EGFR expression increased with World Health Organization grade but did not significantly differ between grade-matched astrocytic and oligodendroglial tumors. Survival did not significantly differ by EGFR expression among astrocytic tumors adjusted for World Health Organization grade. However, grade II oligodendrogliomas with strong EGFR expression and 1p/19q codeletion showed reduced survival, compared with their codeleted counterparts with weaker EGFR expression. Surprisingly, an inverse phenomenon was found with grade III anaplastic oligodendrogliomas, in which stronger EGFR expression was a favorable marker for survival. Among all gliomas, the likelihood of EGFR amplification, as viewed by fluorescence in situ hybridization, increased with the strength of EGFR expression, and <1% of cases with weak or no EGFR immunostaining showed amplification. These data suggest that EGFR IHC is useful in certain circumstances (ie, it may help supplement 1p/19q prognostic information in oligodendroglial tumors and screen out cases that would not benefit from more costly EGFR fluorescence in situ hybridization analysis).

Grading of gliomas: the road from eminence to evidence

The development of concise grading schemes for diffuse gliomas with proven relevance to tumor behavior and susceptibility to therapy is important for clinical decision making. At present, there is unacceptably large interobserver discrepancy in the application of the current World Health Organization (WHO) criteria for accrual of patients in trials for patients with gliomas. Because of a lack of relevant studies, the WHO guidelines for grading are not yet as clear as would be desirable. The development of well-defined grading schemes consisting of features with low interobserver scoring variability and prognostic or predictive relevance is needed. Although interobserver concordance can be tested in retrospective studies, the prognostic or predictive qualities of histological parameters can only be tested in prospective studies. Only evidence-based histopathology will retain its critical role in the diagnosis and treatment of diffuse gliomas.

Loss of chromosome 1p/19q in oligodendroglial tumors: refinement of chromosomal critical regions and evaluation of internexin immunostaining as a surrogate marker

Loss of chromosome 1p/19q in oligodendrogliomas represents a powerful predictor of good prognosis. Expression of internexin (INA), a neuronal specific intermediate filament protein, has recently been proposed as a surrogate marker for 1p/19q deletion based on the high degree of correlation between both parameters in oligodendrogliomas. The aim of this study was to assess further the diagnostic utility of INA expression in a set of genetically well-characterized oligodendrogliomas. On the basis of a conservative approach for copy number determination, using both comparative genomic hybridization and fluorescent in situ hybridization, INA expression as a surrogate marker for 1p/19q loss had both reduced specificity (80%) and sensitivity (79%) compared with respective values of 86% and 96% reported in the previous report. The histologic interpretation and diagnostic value of INA expression in oligodendrogliomas should therefore be assessed with greater caution when compared with 1p/19q DNA copy number analysis. In addition, DNA copy number aberrations of chromosomes 10, 16, and 17 were detected exclusively in 1p/19q codeleted samples, suggesting that other regions of the genome may contribute to the 1p/19q-deleted tumor phenotype inthese samples.

[High-grade gliomas in adults]

BACKGROUND

High-grade glioma is a primary malignant brain tumour which affects about 200 Norwegian patients each year. Diagnosis and treatment of high-grade gliomas in adults has been reviewed.

MATERIAL AND METHODS

The article is based on recent literature retrieved through a non-systematic search in PubMed and the authors' experience with the patient group.

RESULTS

The most common symptoms are focal neurological deficits, epileptic seizures and pressure symptoms. The patients should be examined by magnetic resonance (MR) imaging and the diagnosis confirmed with biopsy. No curative treatment is currently available for high-grade gliomas. The standard treatment is surgical resection followed by radiation therapy alone or in combination with chemotherapy (temozolomid). Five-year survival is only 6.1 %.

INTERPRETATION

The diagnosis is composite with both neurological symptoms and cognitive problems. This requires good communication with the patient and close cooperation between various departments and the primary health services. Symptomatic treatment and multidisciplinary follow-up is necessary.

Alpha-internexin expression predicts outcome in anaplastic oligodendroglial tumors and may positively impact the efficacy of chemotherapy: European organization for research and treatment of cancer trial 26951

BACKGROUND

Although it has been demonstrated that the neuronal intermediate filament alpha-internexin (INA) is closely related to 1p19q codeletion in gliomas, its prognostic and predictive value has not yet been confirmed in a prospective trial. The authors of this report assessed the prognostic significance of INA expression and its correlation with relevant clinical and molecular characteristics in the prospective, randomized European Organization for Research and Treatment of Cancer (EORTC) 26951 trial of adjuvant procarbazine, lomustine, and vincristine (PCV) in patients with anaplastic oligodendroglial tumors (AOTs).

METHODS

INA immunohistochemistry expression in tumors from 92 patients who were included in the EORTC 26951 trial was analyzed independently by 2 observers and was correlated with relevant clinical characteristics, including progression-free survival (PFS) and overall survival (OS), and with molecular features, including 1p/19q codeletion, isocitrate dehydrogenase 1 and 2 gene (IDH1/IDH2) mutation, and O-6 methylguanine-DNA methyltransferase (MGMT) promoter methylation status.

RESULTS

INA expression was observed in 33 tumors and was strongly correlated with 1p/19q codeletion, IDH1 mutations, and MGMT promoter methylation. It was associated with significantly better PFS and OS independent of the treatment received. By using Cox proportional hazard modeling for OS with stepwise selection, INA expression, patient age, and performance status were identified as independent prognostic factors. The results indicated that INA expression may have an impact on the efficacy of combined radiotherapy plus PCV.

CONCLUSIONS

In a homogeneously treated group of patients with grade III AOTs, INA expression had strong favorable prognostic significance for OS and may have predictive value for sensitivity to chemotherapy.

Gone FISHing: clinical lessons learned in brain tumor molecular diagnostics over the last decade

Fluorescence in situ hybridization (FISH) is a powerful, morphology-based technique to assess targeted copy number alterations or gene rearrangements in formalin-fixed, paraffin-embedded tissues. It has a wide range of applications in routine clinical contexts to identify cytogenetic biomarkers for more accurate diagnosis and prognostic stratification. This review and update addresses practical uses of FISH as a molecular diagnostic tool in the setting of brain tumors, including gliomas, embryonal neoplasms, ependymomas and meningiomas, focusing on key genetic biomarkers, such as 1p19q codeletion, epidermal growth factor receptor (EGFR) gene amplification, BRAF rearrangement and many others. Also discussed are lessons learned over the past decade, including common technical issues to consider when implementing and interpreting FISH results in a clinical setting.

First-line temozolomide chemotherapy in progressive low-grade astrocytomas after radiotherapy: molecular characteristics in relation to response

Only a few studies examined the effect of temozolomide (TMZ) in recurrent low-grade astrocytoma (LGA) after surgery, none of which included a homogeneous and sufficiently sized group of patients with progression after radiotherapy (RT). We evaluated a cohort of 58 patients treated with TMZ for progression after RT of a previous LGA and investigated the relation between outcome and mutations in the IDH1, IDH2, and TP53 genes, O⁶-methylguanine-methyltransferase (MGMT) promoter methylation, trisomy of chromosome 7, and loss of chromosomes 1p and 19q. All patients received first-line TMZ 200 mg/m²/day on days 1-5 every 4 weeks for a progressive LGA with a contrast-enhancing lesion on MRI after RT. Six months progression-free survival (PFS) was 67%, and the median overall survival was 14 months. An objective response was obtained in 54%. TP53 mutations and loss of chromosome 19q showed a borderline association with PFS, but none of the other molecular characteristics were correlated with the outcome to TMZ. Both a methylated MGMT promoter gene and IDH1 mutations were found in 86% of the tumor samples. A correlation was found between IDH1 mutations and MGMT promoter methylation (P < .001). Neither MGMT promoter methylation nor IDH1 mutations correlated with PFS, but the interval between the very first symptom of the LGA and the start of the TMZ was significantly longer in the patients with IDH1 mutations (P = .01) and a methylated MGMT promoter (P = .02). We conclude that MGMT promoter methylation and IDH1 mutations seem to predict survival from the time of diagnosis, but not PFS to TMZ.

Oligodendroglial tumors: diagnostic and molecular pathology

Oligodendroglial tumors, which encompass pure oligodendroglioma and mixed oligoastrocytoma, represent the second most common glioma in adults after glioblastoma. They remain controversial neoplasms in the realm of surgical neuropathology. The early recognition of their more favorable prognosis and responsiveness to treatment when compared with diffusely infiltrating astrocytomas has influenced the pathologic diagnostic interpretation, and resulted in a pervasive interobserver variability. The more recent finding of an increased frequency of 1p/19q deletion in these tumors by cytogenetic analysis, and the association of this molecular abnormality with a better prognosis has greatly impacted the field of neuro-oncology. In this review, we focus on important histopathologic aspects in the evaluation of oligodendroglial tumors, key differential diagnoses, and highlight particular clinical and molecular characteristics, as well as current diagnostic and conceptual controversies.

Genomic aberrations associated with outcome in anaplastic oligodendroglial tumors treated within the EORTC phase III trial 26951

Despite similar morphological aspects, anaplastic oligodendroglial tumors (AOTs) form a heterogeneous clinical subgroup of gliomas. The chromosome arms 1p/19q codeletion has been shown to be a relevant biomarker in AOTs and to be perfectly exclusive from EGFR amplification in gliomas. To identify new genomic regions associated with prognosis, 60 AOTs from the EORTC trial 26951 were analyzed retrospectively using BAC-array-based comparative genomic hybridization. The data were processed using a binary tree method. Thirty-three BACs with prognostic value were identified distinguishing four genomic subgroups of AOTs with different prognosis (p < 0.0001). Type I tumors (25%) were characterized by: (1) an EGFR amplification, (2) a poor prognosis, (3) a higher rate of necrosis, and (4) an older age of patients. Type II tumors (21.7%) had: (1) loss of prognostic BACs located on 1p tightly associated with 19q deletion, (2) a longer survival, (3) an oligodendroglioma phenotype, and (4) a frontal location in brain. Type III AOTs (11.7%) exhibited: (1) a deletion of prognostic BACs located on 21q, and (2) a short survival. Finally, type IV tumors (41.7%) had different genomic patterns and prognosis than type I, II and III AOTs. Multivariate analysis showed that genomic type provides additional prognostic data to clinical, imaging and pathological features. Similar results were obtained in the cohort of 45 centrally reviewed–validated cases of AOTs. Whole genome analysis appears useful to screen the numerous genomic abnormalities observed in AOTs and to propose new biomarkers particularly in the non-1p/19q codeleted AOTs.

Interobserver variation of the histopathological diagnosis in clinical trials on glioma: a clinician's perspective

Several studies have provided ample evidence of a clinically significant interobserver variation of the histological diagnosis of glioma. This interobserver variation has an effect on both the typing and grading of glial tumors. Since treatment decisions are based on histological diagnosis and grading, this affects patient care: erroneous classification and grading may result in both over- and undertreatment. In particular, the radiotherapy dosage and the use of chemotherapy are affected by tumor grade and lineage. It also affects the conduct and interpretation of clinical trials on glioma, in particular of studies into grade II and grade III gliomas. Although trials with central pathology review prior to inclusion will result in a more homogeneous patient population, the interpretation and external validity of such trials are still affected by this, and the question whether results of such trials can be generalized to patients diagnosed and treated elsewhere remains to be answered. Although molecular classification may help in typing and grading tumors, as of today this is still in its infancy and unlikely to completely replace histological classification. Routine pathology review in everyday clinical practice should be considered. More objective histological criteria for the grade and lineage of gliomas are urgently needed.

Prospective evaluation of angiogenic, hypoxic and EGFR-related biomarkers in recurrent glioblastoma multiforme treated with cetuximab, bevacizumab and irinotecan

Several recent studies have demonstrated a beneficial effect of anti-angiogenic treatment with the vascular endothelial growth factor-neutralizing antibody bevacizumab in recurrent high-grade glioma. In the current study, immunohistochemical evaluation of biomarkers involved in angiogenesis, hypoxia and mediators of the epidermal growth factor receptor (EGFR) pathway were investigated. Tumor tissue was obtained from a previous phase II study, treating recurrent primary glioblastoma multiforme (GBM) patients with the EGFR inhibitor cetuximab in combination with bevacizumab and irinotecan. Of the 37 patients with available tumor tissue, 29 were evaluable for response. We concurrently performed immunohistochemical stainings on tumor tissue from 21 GBM patients treated with bevacizumab and irinotecan. We found a tendency of correlation between the hypoxia-related markers, indicating that they share the same regulatory mechanisms. None of the EGFR-related biomarkers showed any significant correlations with each other. None of the biomarkers tested alone or in combination could identify a patient population likely to benefit from bevacizumab and irinotecan, with or without the addition of cetuximab. There is still an urgent need for one or more reliable and reproducible biomarkers able to predict the efficacy of anti-angiogenic therapy.

Molecular pathology in adult gliomas: diagnostic, prognostic, and predictive markers

Over the past 10 years, there has been an increasing use of molecular markers in the assessment and management of adult malignant gliomas. Some molecular signatures are used diagnostically to help pathologists classify tumours, whereas others are used to estimate prognosis for patients. Most crucial, however, are those markers that are used to predict response to certain therapies, thereby directing clinicians to a particular treatment while avoiding other potentially deleterious therapies. Recently, large-scale genome-wide surveys have been used to identify new biomarkers that have been rapidly developed as diagnostic and prognostic tools. Given these developments, the pace of discovery of new molecular assays will quicken to facilitate personalised medicine in the setting of malignant glioma.