IDH2 and astrocytoma (excluding glioblastoma): The discovery of the gain-of-function IDH1/2 variants raises therapeutic possibilities outside of IDH variant inhibition, e.g. the apparently important role of glutamine in IDH mutant tumours provides the potential for other therapeutic approaches, such as inhibition of glutaminase in combination with radiotherapy of astrocytoma as well as the possibility of combination therapies [121].