Positive results of Portola's Phase III ANNEXA studies of andexanet alfa

US drug developer Portola Pharmaceuticals (Nasdaq: PTLA) has updated on its development of its investigational antidote to the anticoagulant effects of FXa inhibitors, noting results of the Phase III ANNEXA study have been published online in the New England Journal of Medicine.

ANNEXA-R and ANNEXA-A evaluated the safety and efficacy of andexanet alfa, an which was designated a breakthrough therapy by the US Food and Drug Administration, for reversing the anticoagulant activity of the Factor Xa inhibitors rivaroxaban, Bayer’s (BAYN: DE) Xarelto, and apixaban, Bristol-Myers Squibb (NYSE: BMY) and Pfizer (NYSE: PFE) direct Factor Xa inhibitor Eliquis, respectively, in healthy volunteers.

Results showed that both ANNEXA Part 1 (bolus only) and Part 2 (bolus plus continuous infusion) met all primary and secondary efficacy endpoints, including the measurement of reversal Anti-Xa activity (p<0.0001) for both rivaroxaban and apixaban.