MGMT and glioblastoma: In the case of temozolomide, an additional challenge regards the intrinsic or acquired resistance of GBM cells to alkylating chemotherapeutics through DNA repair, involving, for example, the O6-methylguanine-DNA methyltransferase (MGMT), a better prognosis being expected with such treatment for patients showing methylation of the promoter of the MGMT gene [2].