CLINICAL TRIAL / NCT03011671

Inclusion Criteria: - Histologically proven, newly diagnosed IDH wildtype glioblastoma (GBM) that has a methylated MGMT promoter as assessed by the standardized institutional analysis. - Patients are eligible if they had a prior low grade astrocytoma and there is subsequent histological evidence of a diagnosis of grade III or IV tumor. - Patients must be receiving TMZ as part of their standard adjuvant treatment regimen following treatment with TMZ and Radiation. - Patients must have a Karnofsky performance ≥ 60%. - Normal organ function as follows: - Absolute Neutrophil Count (ANC) ≥ 1.0 x 10^9/ L - Platelets ≥ 100 x 10^9 / L - Hemoglobin ≥ 8.0 g / dL - Age 18 years or older. - Kidney function (creatinine level within normal institutional limit, or creatinine clearance ≥ 60 mL/min/1.73 m2 for patients with creatinine level above institutional normal). - Liver function (AST/ALT <2.5 X institutional upper limit of normal (ULN), Total bilirubin ≤ 1.5 times ULN, INR within 1.5 times ULN (or if receiving anticoagulant therapy an INR of ≤ 3.0 is allowed with concomitant increase in PT or an aPTT ≤ 2.5 × control). - Women able to become pregnant must have a negative pregnancy test within 30 days of registration. - Patients must have the ability to understand and the willingness to sign a written informed consent document. Exclusion Criteria: - Prior invasive malignancy that is not low-grade glioma (except non-melanomatous skin cancer or carcinoma in situ of the cervix) unless the patient has been disease free and off therapy for that disease for a minimum of 3 years. - Active systemic infection requiring treatment, including any HIV infection or toxoplasmosis. - Other severe acute or chronic medical or psychiatric condition, or laboratory abnormality that may increase the risk associated with study participation or study drug administration. - Systemic corticosteroid therapy, >8 mg of dexamethasone daily (or equivalent) at study enrollment. - Pregnant women are excluded from this study, where pregnancy is confirmed by a positive serum beta-hCG laboratory test. Breast-feeding should be discontinued. - Hypersensitivity to acetazolamide or sulfonamides.