GBM is a heterogeneous malignancy comprised of molecular subtypes that not only have relevance to prognosis but also to their response to therapy.5 Methylation of the promoter of the O-6-methylguanine-DNA methyltransferase (MGMT) gene, a direct DNA repair enzyme, is the strongest predictor of response to TMZ in GBM.6,7 Although the median overall survival (OS) of GBM patients treated with combination RT/TMZ is approximately 15 months, in patients with a methylated MGMT promoter, OS is significantly higher.8 This evidence concerns the gene MGMT and glioblastoma.