Andexanet alfa to enter Phase III trials for Factor Xa reversal of anticoagulation - Portola Pharma

Portola Pharmaceuticals announced that it has entered into a second clinical collaboration agreement with Bayer HealthCare and Janssen Pharmaceuticals, Inc. to evaluate its investigational Factor Xa inhibitor reversal agent, andexanet alfa, in Phase III registration studies with the FDA-approved oral Factor Xa inhibitor Xarelto (rivaroxaban). Portola's original collaboration agreement with Bayer and Janssen, announced in February 2013, covered the conduct of a Phase II proof-of-concept study.

Interim results of that study were presented in December 2013 at the 55th American Society of Hematology (ASH) Annual Meeting and demonstrated that andexanet alfa can produce an immediate and dose-dependent reversal of the anticoagulation activity of Xarelto. The new clinical collaboration agreement will be in effect through completion of Phase III studies with Xarelto and any potential U.S. and EU regulatory approval of andexanet alfa. The Phase III studies are expected to start in the first half of 2014.

Portola retains full, worldwide commercial rights to andexanet alfa, which was designated as a breakthrough therapy by the FDA in November 2013 and for which Portola is pursuing an Accelerated Approval pathway.