Antivascular endothelial growth factor monoclonal antibody therapy: a promising paradigm in colorectal cancer.

Angiogenesis plays an important role in tumor growth and development. Vascular endothelial growth factor (VEGF) is one of the most potent proangiogenic factors and therefore is an ideal target in colorectal cancer therapy. Bevacizumab (Avastin, Genentech, Inc., South San Francisco, CA) is a humanized monoclonal antibody, designed to directly target VEGF. The agent has shown promising activity in preclinical and phase I and II studies and is well tolerated compared with conventional cytotoxic chemotherapy. The U.S. Food and Drug Administration recently approved bevacizumab in combination with 5-fluorouracil-based chemotherapy as first-line therapy for patients with metastatic colorectal cancer. The approval was based on phase III data demonstrating that patients treated with bevacizumab plus chemotherapy survived approximately five months longer compared with patients treated with chemotherapy alone. This article will focus on the role of VEGF in tumorigenesis and summarize the available data on the use of bevacizumab in the treatment of metastatic colorectal cancer.