A substance being studied in the treatment of some types of cancer and other conditions. MEDI-522 binds to a protein on the surface of blood vessels and may prevent the growth of new blood vessels that tumors need to grow. It may also prevent the spread of cancer. It is a type of antiangiogenesis agent, a type of metastasis inhibitor, and a type of monoclonal antibody. Also called Abegrin, etaracizumab, and humanized monoclonal antibody MEDI-522.