A humanized monoclonal IgG1 antibody directed against the vitronectin receptor alpha v beta 3 integrin. Etaracizumab blocks the binding of ligands, such as vitronectin, to alpha v beta 3 integrin, resulting in inhibition of angiogenesis and metastasis. Alpha v beta 3 integrin is a cell adhesion and signaling receptor that is expressed on the surface of tumor vessel endothelial cells, some tumor cells, and a number of other cell types.