MGMT and neoplasm: During replication, these adducts become irreversibly bound by the suicide DNA repair enzyme, O6-methyl guanine (O6-MeG) DNA methyltransferase (MGMT), which is then ubiquitinated and targeted for degradation.2 MGMT-mediated DNA repair is a major cause of treatment failure,3,4 and thus promoter methylation status in patient tumours has become a predictive biomarker for response to TMZ.