MGMT and glioblastoma: When GBM patients were divided based on APNG (optimal cutoff) and MGMT status, a significant difference in OS was identified; patients with high APNG expression and methylated MGMT promoter had a median OS of 19.8 months, and patients with low APNG expression and a methylated MGMT promoter had a median OS of 11.2 months (P < 0.001).