Avastin in Combination With Radiation (XRT) & Temozolomide, Followed by Avastin, Temozolomide and Irinotecan for Glioblastoma (GBM) and Gliosarcomas

The standard of care for grade IV gliomas is radiation therapy with daily temozolomide, followed by 6 months of temozolomide. The majority of patients progress and die of their tumor. Many glioma patients are resistant to temozolomide because the tumors have high O(6)-methylguanine-DNA methyltransferase (MGMT), conferring resistance. Irinotecan is synergistic with temozolomide, and the combination may overcome high MGMT. Vascular endothelial growth factor (VEGF) is present on the cell surface and around malignant gliomas. It appears that the presence of vascular endothelial growth factor is a prognostic growth factor with more VEGF expression correlating with a poor prognosis. Monoclonal antibodies to VEGF have inhibited growth of malignant gliomas in a mouse xenograft. Avastin is a humanized monoclonal immunoglobulin G (IGG) 1 antibody that binds to and inhibits the biologic activity of human vascular endothelial growth factor. The combination of Avastin and irinotecan was safe and demonstrated high activity against recurrent malignant gliomas. The combination of Avastin, temozolomide, and irinotecan as the initial therapy may maximize the chance for long-term survival. There are other studies completed or ongoing for newly diagnosed glioblastoma (GBM) patients, including a Radiation Therapy Oncology Group (RTOG) study that added irinotecan to temozolomide following standard radiation therapy and temozolomide, and a University of California, Los Angeles (UCLA) study that added Avastin to standard radiation therapy and temozolomide followed by Avastin and temozolomide.