ClinicalTrials.gov Identifier: NCT00114140.

PURPOSE NRG Oncology/RTOG 9802 (ClinicalTrials.gov Identifier: NCT00003375 ) is a practice-changing study for patients with WHO low-grade glioma (LGG, grade II), as it was the first to demonstrate a survival benefit of adjuvant chemoradiotherapy over radiotherapy. This post hoc study sought to determine the prognostic and predictive impact of the WHO-defined molecular subgroups and corresponding molecular alterations within NRG Oncology/RTOG 9802. METHODS IDH1/2 mutations were determined by immunohistochemistry and/or deep sequencing. A custom Ion AmpliSeq panel was used for mutation analysis. 1p/19q codeletion and MGMT promoter methylation were determined by copy-number arrays and/or Illumina 450K array, respectively. Progression-free survival (PFS) and overall survival (OS) were estimated using the Kaplan-Meier method. Hazard ratios (HRs) were calculated using the Cox proportional hazard model and tested using the log-rank test. Multivariable analyses (MVAs) were performed incorporating treatment and common prognostic factors as covariates. RESULTS Of the eligible patients successfully profiled for the WHO-defined molecular groups (n = 106/251), 26 (24%) were IDH-wild type, 43 (41%) were IDH-mutant/non-codeleted, and 37(35%) were IDH-mutant/codeleted. MVAs demonstrated that WHO subgroup was a significant predictor of PFS after adjustment for clinical variables and treatment. Notably, treatment with postradiation chemotherapy (PCV; procarbazine, lomustine (CCNU), and vincristine) was associated with longer PFS (HR, 0.32; P = .003; HR, 0.13; P < .001) and OS (HR, 0.38; P = .013; HR, 0.21; P = .029) in the IDH-mutant/non-codeleted and IDH-mutant/codeleted subgroups, respectively. In contrast, no significant difference in either PFS or OS was observed with the addition of PCV in the IDH-wild-type subgroup. CONCLUSION This study is the first to report the predictive value of the WHO-defined diagnostic classification in a set of uniformly treated patients with LGG in a clinical trial. Importantly, this post hoc analysis supports the notion that patients with IDH-mutant high-risk LGG regardless of codeletion status receive benefit from the addition of PCV.

Importance The need for a more refined, molecularly-based classification model for glioblastoma (GBM) in the temozolomide era. Objective Refine the existing clinically-based recursive partitioning analysis (RPA) model by incorporating molecular variables. Design, Setting, and Participants NRG Oncology RTOG 0525 specimens (n=452) were analyzed for protein biomarkers representing key pathways in GBM by a quantitative molecular microscopy-based approach with semi-quantitative immunohistochemical validation. Prognostic significance of each protein was examined by single-marker and multi-marker Cox-regression analyses. In order to reclassify the prognostic risk groups, significant protein biomarkers upon single-marker analysis were incorporated into a RPA model consisting of the same clinical variables (age, KPS, extent of resection, and neurologic function) as the existing RTOG RPA. The new RPA model (NRG-GBM-RPA) was confirmed using traditional immunohistochemistry in an independent dataset (n=176). Main Outcomes and Measures Overall survival (OS) Results MGMT (HR=1.81, 95% CI(1.37, 2.39), p<0.001), survivin (HR=1.36, 95% CI(1.04, 1.76), p=0.02), c-Met (HR=1.53, 95% CI(1.06,2.23), p=0.02), pmTOR (HR=0.76, 95% CI(0.60,0.97), p=0.03), and Ki-67 (HR=1.40, 95% CI(1.10, 1.78), p=0.007), were found to be significant upon single-marker multivariate analysis of OS. To refine the existing RPA, significant protein biomarkers together with clinical variables (age, performance status, extent of resection, and neurological function) were incorporated into a new model. Higher MGMT protein was significantly associated with decreased MGMT promoter methylation and vice-versa. Further, MGMT protein expression had greater prognostic value for OS compared to MGMT promoter methylation. The refined NRG-GBM-RPA consisting of MGMT protein, c-Met protein, and age revealed greater separation of OS prognostic classes compared to the existing clinically-based RPA model and MGMT promoter methylation in NRG Oncology RTOG 0525. The prognostic significance of the NRG-GBM-RPA was subsequently confirmed in an independent dataset (N=176). Conclusions and Relevance The new NRG-GBM-RPA model significantly enhances outcome stratification over both the current RTOG RPA model and MGMT promoter methylation, respectively, for GBM patients treated with radiation and temozolomide and was biologically validated in an independent dataset. The revised RPA has the potential to significantly contribute to improving the accurate assessment of prognostic groups in GBM patients treated with radiation and temozolomide and also influence clinical decision making.

The intracellular ratio between methionine and its activated form S-adenosylmethionine (AdoMet) is of crucial importance for the one-carbon metabolism. AdoMet recycling into methionine was believed to be largely achieved through the methyl and the thiomethyladenosine cycles. We show here that in yeast, AdoMet recycling actually occurs mainly through the direct AdoMet-dependent remethylation of homocysteine. Compelling evidences supporting this result were obtained owing to the identification and functional characterization of two new genes, SAM4 and MHT1, that encode the yeast AdoMet-homocysteine methyltransferase and S-methylmethionine-homocysteine methyltransferase, respectively. Homologs of the Sam4 and Mht1 proteins exist in other eucaryotes, indicating that such enzymes would be universal and not restricted to the bacterial or fungal kingdoms. New pathways for AdoMet or S-methylmethionine-dependent methionine synthesis are presented.