MGMT and glioma: To date, there is only limited insight into the mechanisms underlying glioma resistance and only a few resistance markers have been identified, including O6-methylguanine-DNA methyltransferase (MGMT) [4], mutations in the isoforms 1 and 2 of isocitrate dehydrogenase (IDH1/2) [5] and mutations in mismatch repair (MMR) [6].