MGMT and glioblastoma: Diffuse gliomas are the most common adult-onset malignant primary brain tumors.1,2 Despite extensive treatment, median survival for aggressive CNS WHO grade 4 glioblastomas is only 12–18 months.1 The standard-of-care treatment includes maximum safe resection and radiotherapy (RT) with concomitant and maintenance chemotherapy with temozolomide.3 Patients whose glioblastoma harbors methylation of the O6-methylguanine-DNA methyltransferase (MGMT) promoter show higher response rates to temozolomide than those with an unmethylated MGMT promoter.4