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Clinicopathological and molecular landscape of 5-year IDH-wild-type glioblastoma survivors: a multicentric retrospective study

ABSTRACT: Background: Less than 5% of glioblastoma multiforme (GBM) patients survive more than 5-years (long-term survivors, LTS). Nevertheless, the molecular fingerprint of LTS remains uncharted. We aimed to characterize LTS by clinicopathological assessment, DNA methylation (DNAm)/Copy Number Variation (CNV) and mutation profiling. Methods: This multicentric project proposed by Alliance Against Cancer was coordinated by Fondazione IRCCS Istituto Neurologico Carlo Besta. One-hundred forty-two LTS patients were screened, and samples centrally reviewed; 95 patients were enrolled. DNAm profiles and sequencing were performed on 27 LTS and 24 standard survival GBM (STS). Results: We focused on 73 IDHwt-LTS. All patients underwent at least partial resection, followed by Stupp protocol (48/70). The median time to progression was 43 months (4-186), and almost all received a second treatment. Morphological and routine diagnostic molecular features of LTS did not deviate from the classic findings. MGMT promoter methylation was detected in 92% of cases. No significant differences were observed between LTS and STS in terms of prevalence of mutated genes, with TP53 as the most commonly mutated gene (26% of all samples). DNAm showed a more heterogeneous group for LTS, with several cases classified as pediatric high-grade glioma and peculiar CNVs. We identified 18 differentially methylated regions, 4 associated with survival probability (NR2F2, MME, WDR66 and ENPP4). Methylation levels of individual probes in IGFBP3 gene and corresponding protein expression showed a significant correlation with survival. Conclusions: We found no significant different morphology nor mutational profile of LTS. DNAm confirmed as a valuable tool for GBM classification. No specific episignature was detected, but methylation levels of specific genes had prognostic value in LTS.

ORGANISM(S): Homo sapiens

PROVIDER: GSE230770 | GEO | 2024/03/31

REPOSITORIES: GEO

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Project description:Glioblastoma (GBM) is a highly aggressive type of glioma with poor prognosis. However, a small number of patients live much longer than the median survival. A better understanding of these long-term survivors (LTS) may provide important insight into the biology of GBM. We identified 7 patients with GBM treated at Memorial Sloan-Kettering Cancer Center (MSKCC) with survival greater than 48 months. We characterized the transcriptome of each patient and determined rates of MGMT promoter methylation and IDH1 and IDH2 mutational status. We identified LTS in two independent cohorts (TCGA and REMBRANDT) and analyzed the transcriptomal characteristics of these LTS. The median overall survival of our cohort was 62.5 months. LTS were distributed between the proneural (n=2), neural (n=2), classical (n=2) and mesenchymal (n=1) subtypes. Similarly, LTS in the TCGA and REMBRANDT cohorts demonstrated diverse transcriptomal subclassification identity. The majority of the MSKCC LTS (71%) were found to have methylation of the MGMT promoter. None of the patients had an IDH1 or IDH2 mutations, and IDH mutation occurred in a minority of the TCGA LTS as well. A set of 42 genes was found to be differentially expressed in the MSKCC and TCGA LTS. While IDH mutant proneural tumors impart a better prognosis in the short-term, survival beyond 4 years does not require IDH mutation and is not dictated by a single transcriptional subclass. In contrast, MGMT methylation continues to have strong prognostic value for survival beyond 4 years. These findings have substantial impact for understanding GBM biology and progression. All tumors (n = 7) were obtained following surgical resection at the MSKCC as part of routine clinical care, and snap frozen. Tumors were obtained in accordance with Institutional Review Board policies at the MSKCC. Each sample was examined histologically by 3 independent neuropathologists and confirmed to be World Health Organization (WHO) grade IV glioma (GBM). Before analysis, tumors were sectioned and microdissected. Genomic DNA or RNA was extracted using the DNeasy kit (Qiagen) or RNeasy Lipid Tissue Mini Kit (Qiagen) as per the manufacturer’s instructions. Expression analysis of tumors was performed using the Affymetrics U133 2.0 microarray (Affymetrix). Affymetrix CEL files were imported into the Partek Genomics Suite (Partek). The TCGA gene expression data (HT-HG-U133A) was accessed from the TCGA data repositories (http://cancergenome.nih.gov, date of download 12/2013).

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Clinicopathological and molecular landscape of 5-year IDH-wild-type glioblastoma survivors: a multicentric retrospective study

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