• Male or female, aged 18 years and above

• Tumor tissue obtained on a screening consent is available.

• Confirmed with recurrent/progressive IDH-mutant 1p/19q co-deleted Oligodendroglioma WHO grade 2 or WHO grade 3, more than 12 weeks from completion of radiation.

• Karnofsky Performance Status ≥ 60

• Must be a candidate for surgery/biopsy

• Adequate bone marrow and organ function as defined below:

‣ ANC ≥ 1,000/mcL

⁃ Platelets ≥ 100,000/mcL

⁃ Hemoglobin ≥ 9 g/dL (can be transfused)

⁃ Serum creatinine ≤ 1.5 x IULN OR Creatinine clearance by Cockcroft-Gault ≥ 60 mL/min for patients with serum creatinine \> 1.5 x IULN

⁃ Serum total bilirubin ≤ 1.5 x IULN OR Direct bilirubin ≤ IULN for patients with total bilirubin \> 1.5 x IULN

⁃ AST (SGOT) and ALT (SGPT) ≤ 3 x IULN

• For females of childbearing potential, negative serum pregnancy test at enrollment

• For women and men of childbearing potential (WOCBP) must be willing to use acceptable contraceptive methods