MGMT and glioblastoma: In particular, promoter methylation of the O-6-methylguanine-DNA methyltransferase (MGMT) gene is considered to be a predictive biomarker for TMZ-mediated benefits in glioblastoma [60], with an improvement in the progression-free survival (PFS) observed in 39.7% of patients with MGMT promoter-methylated tumors vs. 6.9% without MGMT promoter methylation [61].