On 5 February, Janssen Pharmaceuticals announced a clinical collaboration agreement with Portola Pharmaceuticals and Bayer HealthCare to evaluate the safety of PRT4445 an investigational-stage antidote for Factor Xa inhibitors in healthy volunteers who have been administered the oral anticoagulant rivaroxaban (Xarelto, Jassen Pharmaceuticals). The study will evaluate several dosage strengths of PRT4445 and its ability to reverse the anticoagulant activity of rivaroxaban in emergency situations.
Rivaroxaban is approved by the FDA for six distinct uses. This proof-of-concept study is scheduled to complete in the second half of 2013. A phase 3 trial will be required prior to submitting PRT4445 to the FDA for approval in this setting. Standard clinical measures are currently employed to manage these patients and events.
“Xarelto has the broadest indication profile of any of the new oral anticoagulants in the US market, and is being used by a wide array of patients in many different settings,” said Larry E Fields, senior director, Clinical Development, Medical Affairs, Janssen Pharmaceuticals. “We are committed to exploring ways to expedite reversal of the drug’s effects when necessary, which could provide physicians with an additional treatment option during emergency situations.”
As part of the agreement, Janssen and Bayer will make an upfront payment to Portola and will provide development and regulatory guidance for the study. Portola retains full global development and commercialisation rights for PRT4445.
Portola Pharmaceutical’s PRT4445 is a novel recombinant protein designed to reverse the anticoagulant activity in patients treated with Factor Xa inhibitors suffering from an uncontrolled bleeding episode or undergoing emergency surgery. It is similar to native Factor Xa but has structural modifications intended to restrict its biological activity to reverse the effects of Factor Xa inhibitors. PRT4445 works by binding Factor Xa inhibitors in the blood, thereby preventing them from inhibiting the activity of native Factor Xa. As a result, the native Factor Xa is available to participate in the coagulation process and restore normal clotting.