The epigenetic silencing of MGMT by the methylation of CpG sites in its promoter is associated with longer OS in GBM patients treated with TMZ (Hegi et al., 2005), and MGMT promoter methylation status is both a known prognostic biomarker in GBM and a predictive biomarker of response to TMZ treatment (Weller et al., 2009). The gene discussed is MGMT; the disease is glioblastoma.