MGMT and glioblastoma: In 2005, the Hegi et al. RCT on GBM patients treated with RT and TMZ concluded that patients whose tumor contained a methylated MGMT promoter compared to an unmethylated MGMT promoter had significantly improved OS (21.7 months vs. 12.7 months) and PFS6 (68.9% vs. 40%) (Figure 4) [16].