MGMT and glioblastoma: Meanwhile, the results of clinical trials demonstrated that only 7.8% of nivolumab (PD-1 inhibitor)-treated recurrent GBM patients experienced objective response compared with 23.1% in bevacizumab group, and there is no statistical significance of de novo MGMT-unmethylated GBM between nivolumab and standard radiotherapy compared with temozolomide and radiation therapy group.