Project description:Purpose: The long-term follow-up results from the EORTC-26951 trial showed that the addition of 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 performed 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 demonstrate that methylation profiling can be performed on archival tissues with a performance that is similar to snap frozen tissue samples. We then performed methylation profiling on EORTC-26951 clinical trial samples. Univariate analysis indicated that CIMP+ or MGMT-STP27 methylated tumors had an improved survival compared to CIMP- and/or MGMT-STP27 unmethylated tumors (median overall survival (OS) 1.05 v. 6.46 years and 1.06 v. 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.Multivariate analysis indicates that CIMP and MGMT-STP27 status are prognostic factors for survival independent of age, sex, performance score and review diagnosis. 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. Bisulphite converted DNA from the 58 samples were hybridised to the Illumina Infinium 27k Human Methylation Beadchip The following sample characteristics are provided; OS: overall survival; PFS: progression free survival; CIMP: CpG Island Methylator phenotype; IGS: Intrinsic Glioma subtype; MGMT: O6-methylguanine-DNA-methyltransferase; OR diagn: original diagnosis; Rev diag: review diagnosis; Tum loc: Tumor location; Perf: Performance score; TRT: treatment Performance is based on the ECOG performance status Tum loc: tumor location indicated by 1: Biopsy; 2: Partial Resection; 3: Total Resection. The MGMT promoter methylation status was determined previously (van den Bent et al, J. Clin Oncol 27: 5881-6, 2009) using MS-MLPA and may differ from the MGMT-SPT27 status.

Project description:Background: Intrinsic glioma subtypes (IGS) 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 EORTC26951, a randomized phase III clinical trial investigating adjuvant procarbazine, CCNU (lomustine) and vincristine (PCV) chemotherapy in anaplastic oligodendroglial tumors. Our study is the first to include gene-expression profiles of formalin-fixed and paraffin-embedded (FFPE) clinical trial samples. Methods: Gene-expression profiling was performed in 140 samples: 47 fresh frozen and 93 FFPE, on HU133_Plus_2.0 and HuEx_1.0_st arrays (Affymetrix), respectively. Results: All previously identified six intrinsic glioma subtypes are present in EORTC26951. This confirms that different molecular subtypes are present within a well-defined histological subtype. Intrinsic subtypes are highly prognostic for overall- (OS) and progression-free survival (PFS). They are prognostic for PFS independent of clinical (age, performance, tumor location), molecular (1p19qLOH, IDH1 mutation, MGMT methylation) and histological parameters. Combining known molecular (1p19LOH, IDH1) prognostic parameters with intrinsic subtypes improves outcome prediction (Proportion of Explained Variation 30% v 23%). Specific genetic changes (IDH1, 1p19qLOH and EGFR amplification) segregate into different subtypes. We identified one subtype, IGS-9 (characterized by a high percentage of 1p19qLOH and IDH1 mutations), that especially benefits from PCV chemotherapy. Median OS in this subtype was 5.5 years after radiotherapy (RT) alone v 12.8 years after RT/PCV; P=0.0349; HR 2.18, 95% CI [1.06, 4.50]. Conclusion: Intrinsic subtypes are highly prognostic in EORTC26951 and improve outcome prediction when combined with other prognostic factors. Tumors assigned to IGS-9 benefit from adjuvant PCV A total of 140 samples were included in this study, profiles of 95 were FFPE derived samples run on exon arrays. 12 samples (part 2) can also be found in GSE16011 (PMID 19920198 and 16357140), and 6 from Oncomine (part 3).

Dataset Information

MGMT-STP27 methylation status as Predictive Marker for Response to PCV in Anaplastic Oligodendrogliomas and Oligoastrocytomas; A report from EORTC study 26951

Publications

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

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