MGMT and glioblastoma: Despite the use of TMZ for the treatment of GMB has shown some advantages, such as moderate side effects and increased life expectancy in patients, GBM frequently develops primary and secondary resistance to this drug due to the overexpression of O6-methylguanine-DNA-methyltransferase (MGMT) protein, which can repair the DNA damage induced by TMZ, thus preventing apoptosis of cancer cells and favoring tumor recurrence [15].