Testing the Addition of an Anti-Cancer Drug, Triapine, to the Usual Radiation Therapy for Recurrent Glioblastoma or Astrocytoma

Inclusion Criteria: * Patients must have histologically, molecularly, or cytologically confirmed recurrent astrocytic tumors including: * GBM or variants, IDH-wildtype, grade 2-4 (standard curative measures available or not) * Astrocytoma, IDH-mutant, grade 2-4 (standard curative measures available or not) * Diffuse midline gliomas, including pediatric-type H3 G34 or E3 K27 mutant tumors. * Tumors ≤ 6 cm in maximal diameter. * Patients who had recent resection for recurrent tumor must have measurable disease. * Patients must have at least a 6-month break from last dose of radiation therapy. Re-irradiation within 6 months may increase risk for radiation necrosis/edema, which will affect toxicity assessment and patient safety. Additionally, GBM and other high-grade astrocytic tumors can exhibit pseudo-progression within 6 months from completing definitive, 1st line radiation therapy, and re-irradiation during this period will increase risk for misattribution of effect. * Prior history of standard dose radiation for gliomas of 59.4-60 gray (Gy) in 1.8-2 Gy per fraction (or equivalent or lower) is allowed. * Patients who received non-standard radiation dose regimen (e.g., 40 Gy, 34-35 Gy, 25 Gy) or stereotactic radiosurgery are eligible as long as there is at least one of the following: * A new tumor outside the original radiotherapy field as determined by the investigator. * There is histologic confirmation of tumor on biopsy or resection. * Imaging findings …