IDH1 and glioma: Although WHO grade 2 isocitrate dehydrogenase (IDH)-mutant glioma can be treated with vorasidenib, low-grade astrocytomas (WHO grade 2) progress over time into anaplastic astrocytomas (WHO grade 3) and secondary GBMs (WHO grade 4), which are characterized by vastly increased proliferation and intracerebral dissemination (3).