 Bevacizumab Avastin is a recombinant, humanized, monoclonal antibody directed against vascular endothelial growth factor VEGF. This antibody blocks binding of the ligand VEGF with its receptor. VEGF is known to play a pivotal role in tumor angiogenesis and is a significant mitogenic stimulus for arterial, venous, and lymphatic endothelial cells. It can induce vascular permeability essential for extracellular remodeling and can serve as an endothelial cell survival factor. Phase III studies in 1st line colorectal cancer, 2nd line colorectal cancer, 1st line breast cancer, and 1st line non-small cell lung cancer have all demonstrated clinical benefit in terms of overall survival, progression free survival, and tumor response Refs.. HH NEJM, A Sandler ASCO2005, L Miller ASCO 2005. Efficacy has also been noted in phase II studies of renal cell, ovarian, glioma, and other tumor types. Side effects of bevacizumab include approximately 10-20 rate of hypertension requiring anti-hypertensives, uncommon aterial thromboembolilc events myocardial infarction, unstable angina, cerebrovascular events, transient ischemic attacks, etc with background rates increased from approximately 1-2 to 2-4, and an approximately 1-2 risk of GI perforation. 