The use of engineered monoclonal antibodies as antineoplastic therapy has been a significant advance within the past 15 years. These agents target various receptors and ligands required for the proliferation, survival, or maintenance of angiogenesis of tumors. Currently there are several agents approved by the US Food and Drug Administration for clinical use in solid tumors. Bevacizumab (Avastin) is a humanized monoclonal antibody that targets the vascular endothelial growth factor (VEGF) and inhibits angiogenesis, and is currently approved for the treatment of colorectal, lung, and breast cancer (Avastin package insert, 2008). Trastuzumab (Herceptin) inhibits the HER2/neu receptor, and is utilized in both the adjuvant and palliative settings in breast cancer (Herceptin package insert, 2008).