The addition of the adjuvant drug-alkylating agent temozolomide, which crosses the natural blood–brain barrier to reach intracranial lesions, leading to cellular DNA damage and eventually apoptosis, is the usual treatment for the most malignant glioblastomas; unfortunately, most patients do not benefit from drug therapy due to the presence of the MGMT promoter DNA repair gene18. The gene discussed is MGMT; the disease is glioblastoma.