Univariate and multivariate Cox regression analyses were performed to determine whether the methylation status with a cutoff ≥30% was independently associated with the OS of IDH-mutant GBM cases in cohort A. Univariate Cox analysis indicated that MGMT promoter methylation status [unmethylated vs. methylated, P = 0.001, HR (hazard ratio) = 3.691 (1.689–8.063)] and tumor type [primary vs. recurrent/secondary, P = 0.005, HR = 0.366 (0.182–0.733)], but not age, gender, or extent of resection, significantly correlated with OS (Table 3). This evidence concerns the gene IDH2 and neoplasm.