PRT 4445 (andexanet alfa) meets endpoints in second Phase III trial as an Antidote- Portola Pharma

Portola Pharmaceuticals announced positive topline results from the second part of the Phase III ANNEXA-A study, which evaluated the safety and efficacy of PRT 4445 (andexanet alfa), an investigational antidote, with the Factor Xa inhibitor Eliquis (apixaban) in healthy volunteers. Andexanet alfa was administered as an intravenous (IV) bolus followed by a continuous two-hour infusion to sustain the reversal of anticoagulation activity. This registration-enabling study achieved all primary and secondary endpoints with high statistical significance.

Andexanet alfa produced rapid reversal of the anticoagulant effect of apixaban, as measured by anti-Factor Xa activity, which was sustained for the duration of the infusion. In the study, andexanet alfa was well tolerated, with no serious adverse events, thrombotic events, or antibodies to Factor X or Xa reported. The full data from this second part of the ANNEXA-A study will be presented at an upcoming scientific meeting.

Portola has entered into clinical collaboration agreements with all of the manufacturers of direct Factor Xa inhibitors, including Bristol-Myers Squibb and Pfizer (Eliquis) [apixaban]), Bayer HealthCare and Janssen Pharmaceuticals (XARELTO [rivaroxaban]), and Daiichi Sankyo (Lixiana [edoxaban]), while retaining all rights to the program. Portola plans to submit data from the ANNEXA-A (apixaban) and ANNEXA-R (rivaroxaban) studies, and initial data from a Phase IV study, as part of its Biologics License Application to the FDA under an Accelerated Approval pathway by the end of 2015.