Portola presented in vivo proof of concept data at the 2008 American Society of Hematology Annual Meeting showing that PRT064445 has the potential to act as a universal antidote for reversal of anticoagulation of all current Factor Xa inhibitors, both small molecule and anti-thrombin dependent, including Portola’s own investigational oral direct Factor Xa inhibitor, betrixaban. At the American Heart Association Scientific Sessions 2010, Portola presented preclinical study results demonstrating that PRT064445 can reverse the pharmacodynamic effects of anticoagulation by enoxaparin, a low molecular weight heparin, and fondaparinux, both Factor Xa inhibitors, and reduce blood loss caused by these compounds in an animal model. At the European Society of Cardiology 2011 Congress, Portola presented preclinical study results in an oral session showing that PRT064445 reverses anticoagulant activity of the direct Factor Xa inhibitor rivaroxaban.