Few studies have reported a correlation of promoter methylation at the methylguanine-DNA methyltransferase (MGMT) gene with favorable treatment outcomes in glioblastoma patients treated with temozolamide, suggesting its possibility to be used as an epigenetic biomarker (Donson et al., 2007; Rosas-Alonso et al., 2021; Kim et al., 2022). Here, MGMT is linked to glioblastoma.