Clinical Development Phases I-III Regulatory, Quality, Manufacturing Thrombosis as a clinical phenotype is ubiquitous in human diseases and conditions, ranging from atherosclerosis and other vascular disorders to trauma, surgery, malignancy, infections, blood dyscrasias, auto-immunity, and complications of pregnancy. While each condition carries its own distinct signature and predisposition for thrombosis as a nonphysiological event, there are several common themes that center on cellular and noncellular elements, including well-characterized coagulation proteases. Over the past decade, our group has been actively involved with the development of a factor IXa inhibitor, pegnivacogin, and its complementary antidote or control agent, anivamersen. The following review provides a summary of fundamental constructs, milestones, and the current status of our translational journey. © 2013 Wiley Periodicals, Inc.