Alpha Thalassemia/mental Retardation Syndrome X-linked Expression Research Articles

Monocentric evaluation of Ki-67 labeling index in combination with a modified RPA score as a prognostic factor for survival in IDH-wildtype glioblastoma patients treated with radiochemotherapy

PurposeThe prognosis for glioblastoma patients remains dismal despite intensive research on better treatment options. Molecular and immunohistochemical markers are increasingly being investigated as understanding of their role in disease progression grows. O(6)-methylguanine-DNA methyltransferase (MGMT) promoter methylation has been shown to have prognostic and therapeutic relevance for glioblastoma patients. Other markers implicated in tumor formation and/or malignancy are p53, Alpha thalassemia/mental retardation syndrome X-linked (ATRX), Epidermal Growth Factor Receptor splice variant III (EGFRvIII), and Ki-67, with loss of nuclear ATRX expression and lower Ki-67 index being associated with prolonged survival. For p53 and EGFRvIII the data are contradictory. Our aim was to investigate the markers mentioned above regarding progression-free (PFS) and overall survival (OS) to evaluate their viability as independent prognostic markers for our patient collective.MethodsIn this retrospective study, we collected data on patients undergoing radiotherapy due to isocitrate dehydrogenase (IDH) wildtype glioblastoma at a single university hospital between 2014 and 2020.ResultsOur findings confirm Ki-67 labeling index ≤ 20% as an independent prognostic factor for prolonged PFS as well as MGMT promoter methylation for both prolonged PFS and OS, in consideration of age and Eastern Cooperative Oncology Group (ECOG) status, chemotherapy treatment, and total radiation dose for PFS as well as additionally sex, resection status, and receipt of treatment for progression or recurrence for OS. Additionally, Ki-67 labeling index ≤ 20% showed a significant correlation with prolonged OS in univariate analysis. Modification of the recursive partitioning analysis (RPA) score to include Ki-67 labeling index resulted in a classification with the possible ability to distinguish long-term-survivors from patients with unfavorable prognosis.ConclusionMGMT promoter methylation and Ki-67 labeling index were independent predictors of survival in our collective. We see further studies pooling patient collectives to reach larger patient numbers concerning Ki-67 labeling index as being warranted.

Immunohistochemical expression of ATRX in gliomas

Glioma is one of the primary tumors of the central nervous system that occurs in the spinal cord or brain and the origin of the tumor is from glial cell cells. The most common site of glioma tumors is the brain. Glioma accounts for 30% of all central nervous system tumors and 80% of malignant brain tumors. Alpha-thalassemia/mental retardation syndrome X-linked (ATRX) mutations are frequently distinguished in gliomas. Current research is an attempt to assess ATRX immunoexpression in different types of gliomas diagnosed, in Erbil-Iraq, and to evaluate its association with patient's age, gender, tumor location, grade and type. From January 2015 to January 2017, we reviewed and analyzed 97 cases of glioma. Immunohistochemical staining, for ATRX, was performed using an automated immunostainer technique. According to the WHO grading system for brain tumors, 16 (16.5%) cases were grade I gliomas, 27 (27.8%) were grade II, 10 (10.3%) were anaplastic gliomas (grade III), and 44 (45.3%) cases were glioblastomas WHO (grade IV). Positive ATRX immunoexpression was demonstrated in 27 (27.8%) cases. The highest rates of ATRX expression (55.6%) were among 30-39 years' age group, supratentorial (34.2%), and among grade II and III tumors (40.7% and 30% respectively). A significant association was observed between ATRX expression and patient's age, tumor location, tumor type and grade (p-values 0.010, 0.004, 0.004, and 0.037 respectively). No significant association was found between ATRX expression and patient's gender (p-value 0.097). It was found that ATRX is frequently expressed in grade II and III astrocytomas and was significantly related to the patient's age, tumor location, type and grade, so it can be used as a good diagnostic and prognostic indicator for glioma.

Alternative lengthening of telomeres is the major telomere maintenance mechanism in astrocytoma with isocitrate dehydrogenase 1 mutation

PurposeIsocitrate dehydrogenase 1 (IDH1) mutations are associated with improved survival in gliomas. Depending on the IDH1 status, TERT promoter mutations affect prognosis. IDH1 mutations are associated with alpha-thalassemia/mental retardation syndrome X-linked (ATRX) mutations and alternative lengthening of telomeres (ALT), suggesting an interaction between IDH1 and telomeres. However, little is known how IDH1 mutations affect telomere maintenance.MethodsWe analyzed cell-specific telomere length (CS-TL) on a single cell level in 46 astrocytoma samples (WHO II-IV) by modified immune-quantitative fluorescence in situ hybridization, using endothelial cells as internal reference. In the same samples, we determined IDH1/TERT promoter mutation status and ATRX expression. The interaction of IDH1R132H mutation and CS-TL was studied in vitro using an IDH1R132H doxycycline-inducible glioma cell line system.ResultsVirtually all ALTpositive astrocytomas had normal TERT promoter and lacked ATRX expression. Further, all ALTpositive samples had IDH1R132H mutations, resulting in a significantly longer CS-TL of IDH1R132H gliomas, when compared to their wildtype counterparts. Conversely, TERT promotor mutations were associated with IDHwildtype, ATRX expression, lack of ALT and short CS-TL. ALT, TERT promoter mutations, and CS-TL remained without prognostic significance, when correcting for IDH1 status. In vitro, overexpression of IDHR132H in the glioma cell line LN319 resulted in downregulation of ATRX and rapid TERT-independent telomere lengthening consistent with ALT.ConclusionALT is the major telomere maintenance mechanism in IDHR132H mutated astrocytomas, while TERT promoter mutations were associated with IDHwildtype glioma. IDH1R132H downregulates ATRX expression in vitro resulting in ALT, which may contribute to the strong association of IDH1R132H mutations, ATRX loss, and ALT.

ATRX/EZH2 complex epigenetically regulates FADD/PARP1 axis, contributing to TMZ resistance in glioma.

Rationale: Glioma is the most common primary malignant brain tumor in adults. Chemoresistance of temozolomide (TMZ), the first-line chemotherapeutic agent, is a major issue in the management of patients with glioma. Alterations of alpha thalassemia/mental retardation syndrome X-linked (ATRX) gene constitute one of the most prevalent genetic abnormalities in gliomas. Therefore, elucidation of the role of ATRX contributing to TMZ resistance in glioma is urgently needed.Methods: We performed the bioinformatics analysis of gene expression, and DNA methylation profiling, as well as RNA and ChIP-seq data sets. CRISPR-Cas9 gene editing system was used to achieve the ATRX knockout in TMZ resistant cells. In vitro and in vivo experiments were carried out to investigate the role of ATRX contributing to TMZ resistance in glioma.Results: We found that ATRX expression was upregulated via DNA demethylation mediated by STAT5b/TET2 complex and strengthened DNA damage repair by stabilizing PARP1 protein in TMZ resistant cells. ATRX elicited PARP1 stabilization by the down-regulating of FADD expression via the H3K27me3 enrichment, which was dependent on ATRX/EZH2 complex in TMZ resistant cells. Magnetic resonance imaging (MRI) revealed that the PARP inhibitor together with TMZ inhibited glioma growth in ATRX wild type TMZ resistant intracranial xenograft models.Conclusions: The present study further illustrated the novel mechanism of the ATRX/PARP1 axis contributing to TMZ resistance. Our results provided substantial new evidence that PARP inhibitor might be a potential adjuvant agent in overcoming ATRX mediated TMZ resistance in glioma.

Loss of ATRX expression predicts worse prognosis in pulmonary carcinoid tumors

Loss of alpha thalassemia/mental retardation syndrome X-linked (ATRX), a chromatin regulator, is associated with worse prognosis in pancreatic neuroendocrine tumors. We investigated ATRX expression in pulmonary carcinoid tumors (PCT) and its diagnostic and prognostic role in these patients. Resected PCTs (1997-2017) were reviewed. Tumors were staged according to 8th UICC/AJCC system. ATRX nuclear expression was recorded independently by 2 reviewers. A cutoff of ≤5% of nuclear ATRX expression was statistically established as loss of expression. One-hundred-fifteen patients (72 women [63%]; median age of 60.5 years [interquartile range, 50.8-71.5]) harbored 69 (60%) typical and 46 (40%) atypical PCTs. Median tumor size was 2.3 cm (interquartile range, 1.6-3.8 cm). Loss of ATRX expression was associated with atypical PCTs (OR 7.4 [95% CI, 2.6-23, P < .001]), when adjusted for lymphovascular invasion and perineural invasion. ATRX expression predicted atypical PCT with sensitivity of 37% (95% CI, 24%-52%), specificity of 92% (95% CI, 86%-98%), AUC of 0.62 (95% CI, 0.52-0.72). Loss of ATRX expression was associated with shorter disease-specific survival (HR = 11, 95% CI, 1.8-68, P = .01), after adjusting for lymphovascular invasion and presence of metastatic disease at time of diagnosis. Interobserver agreement on ATRX expression by two reviewers was substantial (κ = 0.72 [95% CI, 0.60-0.80]). ATRX expression is more commonly lost in atypical than in typical PCT, and is associated with more aggressive tumor characteristics and shorter disease-specific survival.

Loss of ATRX/DAXX expression and alternative lengthening of telomeres in uterine leiomyomas.

Uterine leiomyomas (ULs) are the most common gynecologic tumors and affect 3 of every 4 women by the age of 50 years. The majority of ULs are classified as conventional tumors, whereas 10% represent various histopathological subtypes with features that mimic malignancy. These subtypes include cellular and mitotically active ULs and ULs with bizarre nuclei. Uterine leiomyosarcoma (ULMS), the malignant counterpart of UL, is an aggressive cancer with poor overall survival. The early diagnosis and preoperative differentiation of ULMS from UL are often challenging because their symptoms and morphology resemble one another. Recent studies have shown frequent loss of alpha-thalassemia/mental retardation syndrome X-linked (ATRX) or death domain-associated protein (DAXX) expression in ULMS, and this is often associated with an alternative lengthening of telomeres (ALT) phenotype. To investigate ATRX and DAXX expression and the presence of ALT in UL subtypes, immunohistochemical and telomere-specific fluorescence in situ hybridization analyses were performed. The study material consisted of 142 formalin-fixed, paraffin-embedded tissue samples representing various UL subtypes and 64 conventional ULs. A loss of ATRX or DAXX and/or ALT was detected in 6.3% of the histopathological UL subtype samples (9 of 142). Two patients whose ULs showed either ATRX loss or ALT were later diagnosed with a pulmonary smooth muscle tumor. Pulmonary tumors displayed molecular alterations found in the corresponding uterine tumors, which indicated metastasis to the lungs. All conventional ULs displayed normal ATRX, DAXX, and telomeres. These results highlight the differences between conventional and histopathologically atypical ULs and indicate that some UL subtype tumors may harbor long-term malignant potential.

Contrast enhancement predicting survival in integrated molecular subtypes of diffuse glioma: an observational cohort study

To assess the predictive value of magnetic resonance imaging (MRI) gadolinium enhancement as a prognostic factor in the 2016 World Health Organization Classification of Tumors of the Central Nervous System integrated glioma groups. Four-hundred fifty patients with histopathologically confirmed glioma were retrospectively assessed between 07/1997 and 06/2014 using gadolinium enhancement, survival, and relevant prognostic molecular data [isocitrate dehydrogenase (IDH); alpha-thalassemia/mental retardation syndrome X-linked (ATRX); chromosome 1p/19q loss of heterozygosity; and O6-methylguanine DNA methyltransferase (MGMT)]. The Kaplan-Meier method was used to assess univariate survival data. A multivariate Cox proportional hazards model was performed on significant results from the univariate analysis. There were significant differences in survival between patient age (p < 0.0001), WHO glioma grades (p < 0.0001), and integrated molecular profiles (p < 0.0001). Patients with IDH1/2 mutation, loss of ATRX expression, and methylated MGMT promoter showed significantly better survival than those with the IDHwild-type (p < 0.0001), retained ATRX expression (p < 0.0001), and unmethylated MGMT promoter (p = 0.019). Survival was significantly better in patients without gadolinium enhancement (p = 0.009) who were in the IDHwild-type glioma and glioma with retained ATRX expression groups (p = 0.018 and 0.030, respectively). In univariate analysis, the presence of gadolinium enhancement on preoperative MRI scans is an unfavorable factor for survival. Regarding the molecular subgroups, gadolinium enhancement is an unfavorable prognostic factor in gliomas with IDHwild-type and those with ATRX retention. However, in multivariate analysis only patient age, IDH1/2 mutation status, MGMT promoter methylation status, and WHO grade IV are relevant for predicting survival.

In Vivo Molecular Profiling of Human Glioma

To assess the diagnostic performance of dynamic susceptibility contrast perfusion magnetic resonance perfusion imaging (DSC-MRI) for in vivohuman glioma molecular profiling. In this study 100 patients with histopathologically confirmed glioma who provided written informed consent were retrospectively assessed between January 2016 and February 2017 in two prospective trials that were approved by the local institutional review board. Cerebral blood volume (CBV) measurements from DSC-MRI were assessed, and histogram parameters of relative CBV (rCBV) results were compared among World Health Organization (WHO) 2016 based histological findings and molecular characteristics. Aclassification and regression tree (CART) algorithm with 10-fold cross-validation was used to calculate the diagnostic accuracy. The 90th percentile (C90) of rCBV was significantly lower in patients with the isocitrate dehydrogenase 1/2 (IDH1/2) mutation (2.86 ± 1.21; p < 0.001) and loss of alpha-thalassemia mental retardation syndrome X‑linked (ATRX) expression (2.23 ± 0.91; p < 0.001) than in those with the IDH1/2 wild type (4.78 ± 2.34) and maintained ATRX expression (4.30 ± 2.02). The standard deviation (SD) of rCBV was significantly higher in glioblastoma (GBM) with methylated O6-methylguanine DNA methyltransferase (MGMT; 1.99 ± 0.73; p = 0.001) than in those with unmethylated MGMT (1.20 ± 0.45). In CART analysis, rCBV predicted the molecular subgroup in 76.3% of astroglial tumors; however, the diagnostic performance was reduced to 48.1% by including oligodendrogliomas with chromosome 1p/19q co-deletion in the analysis due to substantial overlap of rCBV values between OD1p/19q-LOH and IDHwt GBM. The DSC-MRI procedure may provide insight into the IDH1/2 mutation and ATRX expression status and MGMT methylation profile of diffuse glioma; however, taking integrated oligodendroglioma into account limits the diagnostic performance of rCBV in non-invasively predicting the molecular subtype.

Higher Plasma Fibrinogen Levels are Associated with Malignant Phenotype and Worse Survival in Patients with Glioblastomas.

Preoperative plasma fibrinogen levels were associated with poor clinical outcomes in malignancies. There were few data about the prognostic value of plasma fibrinogen in glioblastomas (GBMs). The objective of our study was to investigate the association between fibrinogen and patients' clinicopathological factors and overall survival (OS). From 2008 to 2016, 315 patients with GBMs who had a surgical treatment at our institute, were retrospectively involved in this study. IDH (isocitrate dehydrogenase) mutations and ATRX (alpha thalassemia/mental retardation syndrome X-linked) loss were detected with IHC (Immunohistochemistry). The preoperative plasma fibrinogen levels ranged from 1.00 to 5.22 g/L, with a mean of were 2.57 g/L. There were increased levels of plasma fibrinogen in patients aged ≥ 65 years, secondary GBMs, IDH mutation (p = 0.033) and ATRX loss (p = 0.040). Moreover, the plasma fibrinogen level was the highest in the subtype of IDH-1R132H wildtype - ATRX expression, which showed a shorter OS compared to the group of IDH-1R132H mut and IDH-1R132H wildtype - ATRX loss (p = 0.001, log-rank test). ROC curves for fibrinogen and IDH-1R132H wildtype - ATRX expression was also plotted, and indicated a potential diagnostic value of fibrinogen in molecular pathology. Univariate analysis found that younger age, higher KPS (Karnofsky Performance Score), gross total resection, complete chemoradiotherapy, IDH-1R132H mutations and lower levels of fibrinogen were associated with favorable outcomes. Multivariate analysis proved that chemoradiotherapy, IDH-1R132H and fibrinogen were independent prognostic factors. In conclusion, plasma fibrinogen could predict clinical outcome and molecular subtype in GBMs.

In vivo molecular profiling of human glioma using diffusion kurtosis imaging.

The purpose of this study is to assess the diagnostic performance of diffusion kurtosis imaging (DKI) for in vivo molecular profiling of human glioma. Normalized mean kurtosis (MKn) and mean diffusivity (MDn) metrics from DKI were assessed in 50 patients with histopathologically confirmed glioma. The results were compared in regard to the WHO-based histological findings and molecular characteristics leading to integrated diagnosis (Haarlem Consensus): isocitrate-dehydrogenase (IDH1/2) mutation status, alpha-thalassemia/mental retardation syndrome X-linked (ATRX) expression, chromosome 1p/19q loss of heterozygosity (LOH), and O6-methylguanine DNA methyltransferase (MGMT) promoter methylation status. MKn was significantly lower in tumors with IDH1/2 mutation (0.43 ± 0.09) and ATRX loss of expression (0.41 ± 0.11) than in those with IDH1/2 wild type (0.57 ± 0.09, p < 0.001) and ATRX maintained expression (0.51 ± 0.10, p = 0.004), respectively. Regarding the integrated molecular diagnosis, MKn was significantly higher in primary glioblastoma (0.57 ± 0.10) than in astrocytoma (0.39 ± 0.11, p < 0.001) and oligodendroglioma (0.47 ± 0.05, p = 0.003). MK may be used to provide insight into the human glioma molecular profile regarding IDH1/2 mutation status and ATRX expression. Considering the diagnostic and prognostic significance of these molecular markers, MK appears to be a promising in vivo biomarker for glioma. The diagnostic performance of MK seems to fit more with the integrated molecular approach than the conventional histological findings of the current WHO 2007 classification.

Immunohistochemical Analysis of ATRX, IDH1 and p53 in Glioblastoma and Their Correlations with Patient Survival.

Glioblastoma (GBM) can be classified into molecular subgroups, on the basis of biomarker expression. Here, we classified our cohort of 163 adult GBMs into molecular subgroups according to the expression of proteins encoded by genes of alpha thalassemia/mental retardation syndrome X-linked (ATRX), isocitrate dehydrogenase (IDH) and TP53. We focused on the survival rate of molecular subgroups, depending on each and various combination of these biomarkers. ATRX, IDH1 and p53 protein expression were evaluated immunohistochemically and Kaplan-Meier analysis were carried out in each group. A total of 15.3% of enrolled GBMs demonstrated loss of ATRX expression (ATRX-), 10.4% expressed an aberrant IDH1 R132H protein (IDH1+), and 48.4% exhibited p53 overexpression (p53+). Survival differences were statistically significant when single protein expression or different combinations of expression of these proteins were analyzed. In conclusion, in the case of single protein expression, the patients with each IDH1+, or ATRX-, or p53- GBMs showed better survival than patients with counterparts protein expressed GBMs. In the case of double protein pairs, the patients with ATRX-/p53-, ATRX-/IDH1+, and IDH1+/p53- GBMs revealed better survival than the patients with GBMs with the remained pairs. In the case of triple protein combinations, the patients with ATRX-/p53-/IDH+ showed statistically significant survival gain than the patients with remained combination of proteins-expression status. Therefore, these three biomarkers, individually and as a combination, can stratify GBMs into prognostically relevant subgroups and have strong prognostic values in adult GBMs.

TERT promoter mutations are a rare event in gastrointestinal stromal tumors.

Recently, the impact of telomere dysregulation on malignant progression has been reported in many cancers. A few studies have examined TERT promoter mutations in gastrointestinal stromal tumors (GISTs). Irregular telomerase activation can be maintained by TERT hot spot alterations and alternative lengthening of telomeres (ALT) characterized by inactivation of either the alpha-thalassemia/mental retardation syndrome X-linked (ATRX) or death domain–associated protein (DAXX). To elucidate the clinicopathological impact of telomere dysregulation in GISTs, we examined 92 cases of GISTs for TERT promoter hot spot mutations along with immunohistochemical analysis of ATRX and DAXX expression, and compared these findings with the clinicopathological features. Univariate clinicopathological analysis revealed that tumor site, smaller tumor size, presence of necrosis, higher mitotic rate (>5/50 high-power fields) and risk classification were prognostic factors for either disease-free survival or overall survival. Two of 92 informative cases (2.2 %) were found to have heterozygous TERT promoter mutations (C228T), and these mutations occurred in a low-risk and a high-risk tumor, respectively. On immunohistochemical analysis for ATRX and DAXX, 16 (17.4 %) and 3 (3.3 %) of 92 cases showed loss of expression of ATRX and DAXX, respectively. Loss of expression of ATRX and DAXX were mutually exclusive except for one case. TERT promoter mutations were also mutually exclusive of the ALT phenotype. Telomere dysregulation was not associated with patient survival; however, telomere dysregulation was frequently observed in tumors of extra-gastric origin, which have an adverse outcome compared to those of gastric origin.Electronic supplementary materialThe online version of this article (doi:10.1186/s40064-015-1606-2) contains supplementary material, which is available to authorized users.

MPTH-30ATRX CAN OCCUR IN IDH WILD-TYPE GBM

BACKGROUND: ATRX (alpha thalassemia/ mental retardation syndrome X-linked) is a transcriptional regulatory protein which contains an ATPase/helicase domain. In gliomas loss of ATRX expression has been recently described and is mostly restricted to IDH mutant tumors who seem to have a significantly better prognosis. ATRX loss is thought to be extremely rare in IDH wild type (WT) tumors and in that setting one group reported H3F3A mutation. METHODS: Tissue samples of 23 patients with IDH wild-type malignant gliomas were analyzed for ATRX expression using immunohistochemistry. ATRX status was associated with clinical characteristics, histology and other molecular markers (MGMT, BRAF, EGFR). RESULTS: Median age in all patients was 49,3 years. Loss of ATRX expression was detected in 4 out of 23 patient tumors. All ATRX loss patients were primary glioblastomas. Median survival in ATRX mutated gliomas is 237 weeks which was longer than overall survival in gliomas with retained ATRX (88 weeks). All of our patients underwent concurrent chemoradiotherapy with temozolomide. One out of four ATRX loss tumors was BRAF mutated, three out of four ATRX loss patients tested for EGFR were found to be wild type and the two ATRX mutated patients tested for MGMT were methylated. CONCLUSION: ATRX mutation can occur in IDH wild-type patients. In that setting it appears to be associated with a better outcome. Our data is hypothesis generating. Tumors with IDH WT/ ATRX loss should be evaluated prospectively in a larger cohort and possibly checked for H3F3A mutation.

MPTH-01ESTABLISHMENT OF A RAPID AND EFFICIENT GENETIC ANALYSIS SYSTEM OF GLIOMAS

PURPOSE: Of the genetic mutations seen in gliomas, IDH1/2 mutations, chromosome 1p/19q loss, MGMT promoter methylation, and genetic alterations of TERT promoter, BRAF, and H3F3A, have become increasingly important as biomarkers for the diagnosis, prognostication, and treatment response of gliomas. Here we report on the establishment of a system, within our institution, of the efficient and rapid detection of these genetic mutations. METHODS: Tumor-derived DNA and RNA extracted from either frozen or paraffin-embedded histological sections were used as specimens. For the point mutation assay, the following mutations of: IDH1/2, H3F3A, BRAF codon 600, and the TERT promoter were screened using High Resolution Melting (HRM) method, and identified by DNA sequencing. For the MGMT promoter methylation, a quantitative analysis was performed using the methylation-specific HRM method. Real-time PCR was used for determining the presence or absence of the BRAF-KIAA fusion gene, and FISH was used for detecting chromosome 1p/19q loss. Further, immunostaining was performed to analyze loss of ATRX (alpha-thalassemia/mental-retardation syndrome-X-linked) expression. RESULTS: Screening of each of the genetic mutations by the point mutation assay using the HRM method was completed in one run of approximately 70 minutes. Furthermore, all genetic mutation results were obtained within 5 ∼ 72 hours after nucleic acid extraction using our assay system. CONCLUSION: For clinics that specialize in diagnosis and treatment of brain tumors, the genetic biomarker information mentioned above will become indispensible in the future. Outsourcing this testing has issues relating to cost and time to obtaining results, and thus testing in-house is desirable. Utilizing PCR primer settings that allow the screening of multiple genetic mutations in one run, and simple and sensitive/specific assays such as the HRM method, allows efficient and rapid analysis.

Ileal neuroendocrine tumors show elevated activation of mammalian target of rapamycin complex

BackgroundNeuroendocrine tumors (NETs) of the ileum are sporadic tumors derived from submucosal gastrointestinal stem cells. They often show clinical symptoms only after hepatic metastasation when curative therapy is limited or impossible. In this study, we analyzed the expression of the candidate genes mammalian target of rapamycin (mTOR), alpha thalassemia/mental retardation syndrome X-linked (ATRX), and death domain-associated protein (DAXX) to investigate the specific oncogenetics and potential therapeutic options for ileal NETs. MethodsIn a prospective database, all patients who underwent surgical removal of a NET of the ileum between 2001 and 2011 were specified. Expression analysis was performed for mTOR, ATRX, and DAXX by immunohistochemistry of paraffin-embedded tumor samples. To evaluate the results the immunoreactive score was applied. Normal tissue and tumor tissue were analyzed for the comparison of gene expression levels using quantitative-real-time polymerase chain reaction for ATRX and mTOR genes. Results were correlated under pathologic and clinical aspects. ResultsA total of 69 patients were admitted to the study. Positive cytosolic expression of the potential oncogene mTOR was immunohistochemically detected in 76.2% of the human probes. A loss of nuclear ATRX expression was detected in 13.0% of the samples. A nonexpression of the DAXX-protein in cell nuclei was not found (0%). Gene transcript levels did not show a significant alteration in ileal NETs in comparison with normal tissue. ConclusionsmTOR is overexpressed in ileal NETs. Additionally, the loss of ATRX expression was registered, thus underlying a tumorigenic role in a subgroup of these tumors. To enable potential therapeutic application of mTOR inhibitors, further trials with larger study groups are needed.

P17.71 * ROLE OF ATRX AND TERT EXPRESSION AS DIAGNOSTIC AND PROGNOSTIC FACTORS ON ANAPLASTIC GLIOMAS

Molecular and histological classification of anaplastic gliomas have been recently refined by the elucidation of the role of mutations in alpha thalassemia/mental retardation syndrome X-linked (ATRX) gene and in telomerase reverse transcriptase (TERT) promoter. Loss of ATRX expression and the acquisition of alternative lengthening of telomeres (ALT) phenotype is peculiar of a subtype of astrocytic tumours with p53 and IDH1 mutations and better prognosis, while TERT overexpression, due to its promoter's mutations, is strongly associated to oligodendroglial tumours and 1p/19q codeletion, without a significant correlation with survival. Based on these findings, the aim of our study was to better clarify the role of ATRX and TERT expression in the histological classification of anaplastic gliomas, as diagnostic and prognostic markers of survival and relapse. We performed immunohistochemical and molecular analysis of ATRX and TERT expression on 60 grade III gliomas (astrocytomas, oligoastrocytomas and oligodendrogliomas) and the respective recurrences when they were available. Nuclear accumulation of p53, IDH1 status and LOH of chromosomes 1p, 19q, 9p, 17p and 10q were also evaluated. Our results showed a loss of ATRX expression in 60% of anaplastic oligoastrocytomas and 40% of anaplastic astrocytomas, while ATRX was wild-type in oligodendroglial tumours. We then found a strong positive correlation between loss of ATRX expression and p53 nuclear accumulation, while its strong expression was present mostly in tumours with 1p/19q codeletion. Finally, ATRX loss was correlated with a better prognosis both in anaplastic oligoastrocytomas and in anaplastic astrocytomas according to literature. Regarding TERT expression, we did not find a strictly correlation with 1p/19p codeletion and the oligodendroglial histological pattern, but, surprisingly, we found a possible role in relapse of anaplastic gliomas. In our series, tumours with high TERT expression tend to recur within 25 months, while anaplastic gliomas with low o null expression of TERT tend to recur within 60 months. In conclusion, these set of data could allow us in the future to better classify anaplastic gliomas and their tendency to recur adding immunohistochemistry for ATRX and TERT to other molecular markers in routine diagnostic procedures, and to define new molecular profiles for their therapy.

O8.06 * ATRX AND TERT EXPRESSION IN RELAPSING LOW GRADE GLIOMA

Mechanisms responsible for telomere maintenance are been recently elucidated: many cancers harbor mutations in alpha thalassemia/mental retardation syndrome X-linked (ATRX) gene resulting in a phenomenon known as alternative lengthening of telomeres (ALT) or point mutations in the promoter of the telomerase reverse transcriptase (TERT) gene leading to an increased telomerase expression. ATRX and TERT mutations have been recently identified also in brain tumors. In gliomas, a molecular stratification based on IDH and ATRX mutational status and 1p/19q codeletion has been suggested. ATRX mutations have been observed mainly in astrocytic tumors and TERT promoter mutations mainly in oligodendroglial tumors. Aim of our study was to evaluate the expression of both ATRX and TERT in WHO grade II gliomas and in their resected recurrences, related to a set of confirmed molecular markers and to clinical data. We performed an immunohistochemical analysis of ATRX and TERT expression in 30 grade II gliomas (astrocytomas, oligoastrocytomas and oligodendroglioma) and in their respective recurrences (grade III-IV). Also evaluation of IDH1 and p53 status and 1p/19q LOH were carried out. Loss of expression of ATRX protein has been associated to the mutated gene and ALT phenotype, while expression of TERT protein could be related to TERT promoter mutations. We found a loss of ATRX expression in 70% of cases; recurrences showed the same pattern of ATRX expression. In the most part of cases ATRX loss was associated to IDH1 and p53 mutation and intact 1p/19q, as previously observed. In the major part of cases with ATRX loss of expression TERT was not detected. TERT high expression was observed in about 30% of grade II gliomas at the first surgery, minor expression of TERT was found in grade III-IV recurrent tumors. In most case high expression of TERT was associated to 1p/19q deletion. We observed a statistically significant correlation between TERT high expression and a better outcome. Our study of protein expression of both ATRX and TERT in low grade gliomas and in their recurrences in relationship with established molecular markers and follow-up data, confirm the possibility of using immunohistochemistry in routine diagnostic procedures for better define this subset of neoplasm.

O10.01 * PROGNOSTIC AND PREDICTIVE BIOMARKER-BASED SUBGROUPS IN THE NOA-04 TRIAL

BACKGROUND: Molecular biomarkers, including isocitrate dehydrogenase 1 or 2 (IDH1/2) mutation, 1p/19q codeletion, mutations and (consequently) loss of expression of alpha-thalassemia/mental retardation syndrome X-linked (ATRX) and O6-methylguanine-DNA-methyltransferase (MGMT) promoter methylation, improve prognostication and may even guide treatment decisions in patients with anaplastic gliomas. Illumina Infinium HumanMethylation450 BeadChip arrays (HM450) allow the determination of large-scale methylation profiles and genome-wide DNA copy number changes, enabling molecular subgrouping of tumors. In addition, algorithms have been developed to detect the glioma CpG island methylator phenotype (G-CIMP) associated with IDH1/2 mutation, 1p/19q codeletion and MGMT promoter methylation using this assay. METHODS: In the biomarker cohort of the NOA-04 trial, the diagnostic and prognostic performance of these molecular markers using single tests, HM450 data and HM450-based algorithms has been investigated to propose biological subgroups, which reflect outcomes and potentially influence treatment decisions. RESULTS: Loss of ATRX expression was detected in 45% of anaplastic astrocytomas (AA), 27% of anaplastic oligoastrocytomas (AOA) and 10% of anaplastic oligodendrogliomas (AO). It was mostly restricted to IDH mutant tumors and almost mutually exclusive with 1p/19q co-deletion. In tumors with IDH1 mutation, MGMT promoter methylation was associated with prolonged progression-free survival (PFS) with chemotherapy or radiotherapy (RT), and thus prognostic. In tumors without IDH1 mutation, MGMT promoter methylation was associated with increased PFS in patients treated with chemotherapy, too, but not in those who received RT alone as the first-line treatment, and is thus chemotherapy-predictive. Comparisons of single assays and HM450-based algorithms revealed a high concordance for IDH and 1p/19q status. The HM450-derived MGMT-STP27 model to calculate MGMT promoter methylation probability revealed this aberration in a significantly higher fraction of cases as conventional methylation-specific PCR, with 87/91 G-CIMP-positive tumors predicted as MGMT promoter-methylated. CONCLUSIONS: ATRX loss is a hallmark and favorable prognosticator of astrocytic tumors allowing a better definition of the clinically and morphologically mixed group of AOA. MGMT promoter methylation is a predictive biomarker for benefit from alkylating agent chemotherapy in patients with IDH1-wildtype, but not IDH1-mutant malignant gliomas of WHO grades III/IV. Combined IDH1/ MGMT assessment may help to individualize clinical decision making in neurooncology. G-CIMP and 1p/19q codeletion are reliably detectable by HM450 analysis and associated with prognosis in the NOA-04 trial. HM450 arrays allowed clustering of anaplastic gliomas into relevant subgroups.

PROGNOSTIC AND PREDICTIVE BIOMARKER-BASED SUBGROUPS IN THE NOA-04 TRIAL

BACKGROUND: The WHO classification, based on morphological criteria, may be increasingly supplemented with defined molecular aberrations. These might help to resolve the discrepancy between classification and clinical outcome. Molecular biomarkers, including isocitrate dehydrogenase 1 or 2 (IDH1/2) mutation, 1p/19q codeletion, mutations and (consequently) loss of expression of alpha-thalassemia/mental retardation syndrome X-linked (ATRX) and O6-methylguanine-DNA-methyltransferase (MGMT) promoter methylation, improve prognostication and may even guide treatment decisions in patients with anaplastic gliomas. Illumina Infinium HumanMethylation450 BeadChip arrays (HM450) allow the determination of large-scale methylation profiles and genome-wide DNA copy number changes, enabling molecular subgrouping of tumors. In addition, algorithms have been developed to detect the glioma CpG island methylator phenotype (G-CIMP) associated with IDH1/2 mutation, 1p/19q codeletion and MGMT promoter methylation using this assay. METHODS: In the biomarker cohort of the NOA-04 trial, the diagnostic and prognostic performance of these molecular markers using single tests, HM450 data and HM450-based algorithms has been investigated to propose biological subgroups, which reflect outcomes and potentially influence treatment decisions. RESULTS: Loss of ATRX expression was detected in 45% of anaplastic astrocytomas (AA), 27% of anaplastic oligoastrocytomas (AOA) and 10% of anaplastic oligodendrogliomas (AO). It was mostly restricted to IDH mutant tumors and almost mutually exclusive with 1p/19q co-deletion. In tumors with IDH1 mutation, MGMT promoter methylation was associated with prolonged progression-free survival (PFS) with chemotherapy or radiotherapy (RT), and thus prognostic. In tumors without IDH1 mutation, MGMT promoter methylation was associated with increased PFS in patients treated with chemotherapy, too, but not in those who received RT alone as the first-line treatment, and is thus chemotherapy-predictive. Comparisons of single assays and HM450-based algorithms revealed a high concordance for IDH and 1p/19q status. The HM450-derived MGMT-STP27 model to calculate MGMT promoter methylation probability revealed this aberration in a significantly higher fraction of cases as conventional methylation-specific PCR, with 87/91 G-CIMP-positive tumors predicted as MGMT promoter-methylated. CONCLUSIONS: ATRX loss is a hallmark and favorable prognosticator of astrocytic tumors allowing a better definition of the clinically and morphologically mixed group of AOA. MGMT promoter methylation is a predictive biomarker for benefit from alkylating agent chemotherapy in patients with IDH1-wildtype, but not IDH1-mutant malignant gliomas of WHO grades III/IV. Combined IDH1/ MGMT assessment may help to individualize clinical decision making in neurooncology. G-CIMP and 1p/19q codeletion are reliably detectable by HM450 analysis and associated with prognosis in the NOA-04 trial. HM450 arrays allowed clustering of anaplastic gliomas into relevant subgroups. SECONDARY CATEGORY: Tumor Biology.

The alternative lengthening of telomere phenotype is significantly associated with loss of ATRX expression in high-grade pediatric and adult astrocytomas: a multi-institutional study of 214 astrocytomas

Loss-of-function of alpha thalassemia/mental retardation syndrome X-linked (ATRX) protein leads to a phenotype called alternative lengthening of telomeres (ALT) in some tumors. High-grade astrocytomas comprise a heterogeneous group of central nervous system tumors. We examined a large cohort of adult (91) and pediatric (n=88) high-grade astrocytomas as well as lower grade forms (n=35) for immunohistochemical loss of ATRX protein expression and the presence of ALT using telomere-specific fluorescence in situ hybridization, with further correlation to other known genetic alterations. We found that in pediatric high-grade astrocytomas, 29.6% of tumors were positive for ALT and 24.5% were immunonegative for the ATRX protein, these two alterations being highly associated with one another (P<0.0001). In adult high-grade astrocytomas, 26.4% of tumors were similarly positive for ALT, including 80% of ATRX protein immunonegative cases (P<0.0001). Similar frequencies were found in 11 adult low-grade astrocytomas, whereas all 24 pilocytic astrocytomas were negative for ALT. We did not find any significant correlations between isocitrate dehydrogenase status and either ALT positivity or ATRX protein expression in our adult high-grade astrocytomas. In both cohorts, however, the ALT positive high-grade astrocytomas showed more frequent amplification of the platelet-derived growth factor receptor alpha gene (PDGFRA; 45% and 50%, respectively) than the ALT negative counterparts (18% and 26%; P=0.03 for each). In summary, our data show that the ALT and ATRX protein alterations are common in both pediatric and adult high-grade astrocytomas, often with associated PDGFRA gene amplification.