IDH2 and glioblastoma: Despite multifaceted therapies, the 5-year survival rate is only 5%.1,2 The median age of onset in isocitrate dehydrogenase (IDH)-wildtype GBM is over 60; these tumors do not have tumorigenic mutations in either of the IDH genes (IDH1, IDH2).2,3 The mechanisms responsible for increased incidence with age are not fully understood but include accumulation of genomic damage, altered epigenetic states, and changes to the microenvironment.