Telaglenastat With Radiation Therapy and Temozolomide in Treating Patients With IDH-Mutated Diffuse Astrocytoma or Anaplastic Astrocytoma

Inclusion Criteria: * Patients must have histopathologic or molecular confirmation of either IDH-mutant DA or IDH-mutant AA. Acceptable IDH mutations for study eligibility include any IDH1 mutation at codon 132 or any IDH2 mutation at codon 172. * Age \>= 16 years. The intended neurocognitive tests have not been validated in children below the age of 16. * Eastern Cooperative Oncology Group (ECOG) performance status =\< 1 (Karnofsky \>= 70%). * Hemoglobin \> 9.0 g/dL (within 14 days prior to registration) * Leukocytes \>= 3.0 x 10\^9/L (within 14 days prior to registration) * Absolute neutrophil count \>= 1.5 x 10\^9/L (within 14 days prior to registration) * Platelets \>= 100 x 10\^9/L (within 14 days prior to registration) * International normalized ratio (INR) =\< 1.5 x upper limit of normal (ULN) (within 14 days prior to registration) * Partial thromboplastin time (PTT) or activated partial thromboplastin time (APTT) =\< 1.5 x ULN (within 14 days prior to registration) * Patients on a stable dose of anti-coagulation therapy will be allowed to participate if they have no signs of bleeding or clotting and the INR/PT and PTT/aPTT results are compatible with an acceptable risk-benefit ratio as per the investigator's discretion. * Total bilirubin =\< 1.5 x institutional ULN and \< 3 mg/dL for patients with Gilbert's disease (within 14 days prior to registration) * Aspartate aminotransferase (AST) (serum glutamic-oxaloacetic transaminase \[SGOT\]) \& alanine aminotransferase (…