Phase 3 Study of Vorasidenib (S095032/AG-881) in Asian Participants With Residual or Recurrent Grade 2 Glioma With an IDH1 orIDH2 Mutation

Inclusion Criteria: * Be at least 12 years of age (for Randomized Double-Blind phase) and weigh at least 40 kg. * Have a Karnofsky Performance Scale (KPS) score (for participants ≥16 years of age) or Lansky Play Performance Scale (LPPS) score (for participants \<16 years of age) of ≥80%. * Have Grade 2 oligodendroglioma or astrocytoma per WHO 2016 criteria. * Have had at least 1 prior surgery for glioma with the most recent one having occurred at least 1 year (-1 month) and not more than 5 years (+3 months) before randomization, and no other prior anticancer therapy, including radiotherapy and not be in need of immediate chemotherapy or radiotherapy. * Have confirmed IDH1 (IDH1 R132H/C/G/S/L mutation variants tested) or IDH2 (IDH2 R172K/M/W/S/G mutation variants tested) gene mutation status disease * Have MRI-evaluable, measurable, non-enhancing disease, as confirmed by the BIRC for double blind part. Exclusion Criteria: * Have had any prior anticancer therapy other than surgery (biopsy, sub-total resection, gross-total resection) for treatment of glioma including systemic chemotherapy, radiotherapy, vaccines, small-molecules, IDH inhibitors, investigational agents, laser ablation, etc. * Concurrent active malignancy except for a) curatively resected nonmelanoma skin cancer or b) curatively treated carcinoma in situ. Participants with previously treated malignancies are eligible provided they have been disease-free for 3 years at Screening. * Have any other acute or chroni…