Testing Addition of an Anti-cancer Drug, Vorasidenib to Temozolomide, After Radiation for Advanced Brain Cancer

This phase III trial compares the effect of vorasidenib to placebo in combination with usual treatment, temozolomide, in treating patients with newly diagnosed grade 3 astrocytoma after radiation. Temozolomide is in a class of medications called alkylating agents. It works by damaging the cell\'s deoxyribonucleic acid and may kill tumor cells and slow down or stop tumor growth. Vorasidenib citrate blocks the proteins made by the mutated IDH1 and IDH2 genes, which may help keep tumor cells from growing. It is a type of enzyme inhibitor and a type of targeted therapy. Adding vorasidenib to the usual treatment, temozolomide, may be more effective than temozolomide alone in treating patients with newly diagnosed grade 3 astrocytoma after radiation therapy.