Efficacy Study of Oral Arginine to Improve Immune Function in Glioblastoma Multiforme

Inclusion Criteria: 1. Age 18 and above. 2. Imaging consistent with GBM without clinical indication for primary CNS lymphoma or abscess, as determined by the treating physician. 3. Patient must be planned to proceed to definitive surgery intended for tumor resection, rather than needle biopsy, within a reasonable time frame from initial evaluation (7-14 days). 4. Patient must be neurologically stable, allowing for reasonable time frame between initial evaluation and subsequent surgical procedure (7-14 days). 5. Patient must have initial KPS greater than 80. 6. At the time of initial evaluation the patient must be on a stable dose of steroid medication if indicated. 7. Patient must have laboratory values, as determined by institutional controls, within the following parameters: * White blood cell count above lowest level for normal range * Renal function within normal limits (creatinine, BUN) * Liver function within normal limits (AST/ALT, total bilirubin, alkaline phosphatase) 8. Written informed consent is obtained prior to initiation of study procedures. Exclusion Criteria: 1. Known autoimmune condition, underlying immune disease, or use of immunomodulatory prescription drugs (aside from steroids) for any medical condition. 2. Prescribed vasodilator medications: Phosphodiesterase Inhibitors: Sildenafil (Viagra), Nitrates, Alpha blockers: Terazosin (Hytrin), doxazosin (Cardura), alfuzosin (Uroxatral), tamsulosin (Flomax), and prazosin (Minipress). 3. Glaucoma 4. Known Herpes simplex virus (i.e. cold sores) 5. History of myocardial infarction or coronary artery disease. 6. Known allergy or intolerance to arginine. 7. Uncontrolled or poorly controlled seizures. 8. KPS less than 80. 9. Known renal or hepatic insufficiency or failure. 10. Known deficiency or dysfunction of intestinal absorption or motility. 11. History of other malignancy regardless of current status or treatment. 12. Underlying psychiatric condition or altered mental status that would violate stringent acquisition of informed consent or potentially preclude, in the opinion of the investigator, compliance with study requirements 13. Pregnancy