MGMT and glioblastoma: Similarly, the results of CheckMate-498 and Checkmate-548, which investigated the addition of concurrent nivolumab to radiotherapy in patients with O6-methylguanine-DNA methyltransferase (MGMT)-unmethylated glioblastoma multiforme (GBM) and temozolomide and radiotherapy in patients with MGMT-methylated GBM, respectively, failed to demonstrate the efficacy of nivolumab in these settings [17,18,19,20,21].