Blood samples will be obtained from newly diagnosed GBM patients treated with combined radiotherapy (RT), temozolomide (TMZ) and bevacizumab (BEV) at specific time points. The primary outcome is the shift in T reg cell fraction a defined by determining the proportion of CD4 cells that are CD4+ CD25.

Glioblastoma multiforme (GBM) is the most frequent malignant brain tumor and it remains a lethal disease. Approximately 4 weeks post surgery for tumor resection, patients will proceed to standard of care treatment which currently consists of temozolomide (TMZ) with concurrent radiation therapy (RT) for 6 weeks. This study will add bevacizumab (BEV) to the standard of care regimen in newly diagnosed patients. The Bevacizumab will be added 2 weeks post start of RT/TMZ. Administration of bevacizumab will continue concurrently with TMZ every 2 weeks for 12 months. Blood samples will be obtained from these patients at 3 different time points during this study.

Inclusion Criteria:

• Histologically proven GBM
• Karnofsky status equal to or greater than 60%

Exclusion Criteria:

• Inadequately controlled hypertension
• Prior history of hypertension crisis or hypertensive encephalopathy
• History of stroke or transient ischemic attach within 12 months