Portola Enters Second Clinical Collaboration Deal With Bristol-Myers And Pfizer

(RTTNews) - Portola Pharmaceuticals (PTLA) announced that it has entered into a second clinical collaboration agreement with Bristol-Myers Squibb Company (BMY) and Pfizer Inc. (PFE) to study Portola's investigational Factor Xa inhibitor reversal agent, andexanet alfa (PRT4445), with the oral Factor Xa inhibitor Eliquis (apixaban). The original agreement, announced in November 2012, covered the conduct of a Phase 2 proof-of-concept study.

Results of the Phase 2 study were presented at the 2013 Congress of the International Society on Thrombosis and Haemostasis or ISTH and demonstrated andexanet alfa's ability to produce an immediate and either temporary or sustained reversal of the anticoagulation activity of Eliquis.

Portola stated that the new clinical collaboration agreement will be in effect through Phase 3 studies with Eliquis and any potential U.S. and EU regulatory approval of andexanet alfa. The Phase 3 studies are expected to start in the first half of 2014.

Under this non-exclusive collaboration agreement, Portola will receive an upfront payment and is eligible to receive additional development and regulatory milestone payments. Bristol-Myers Squibb and Pfizer will continue to provide development and regulatory guidance for the program. Portola retains full, worldwide commercial rights to andexanet alfa, which was designated as a breakthrough therapy by the U.S. Food and Drug Administration or FDA in November 2013 and for which Portola is pursuing an Accelerated Approval pathway.

Andexanet alfa is a first-in-class recombinant, modified Factor Xa molecule being developed as a direct reversal agent (antidote) for patients receiving a Factor Xa inhibitor who suffer an uncontrolled bleeding episode or who require emergency surgery. Andexanet alfa acts as a Factor Xa decoy that targets and sequesters with high specificity both direct and indirect Factor Xa inhibitors in the blood.

Once bound, the Factor Xa inhibitors are unable to bind to and inhibit native Factor Xa, thus allowing for the restoration of normal hemostatic processes. Through its mechanism of action, andexanet alfa has the potential to act as a universal antidote and address the direct cause of the patient's inhibited clotting activity without being prothrombotic.