RecruitingPhase 2Drug trialG-CSF After Chemo-radiation in Patients With GlioblastomaThis research study involves the study of granulocyte colony stimulating factor (G-CSF) in patients with MGMT-methylated glioblastoma multiforme (GBM) that are undergoing standard chemoradiation. The study aims to evaluate G-CSF's effects on brain health and cognitive function. The name of the study drugs involved in this study are: * G-CSF (also called Filgrastim) * Temozolomide (TMZ), a standard of care chemotherapy drug