Andexanet alfa: FXa Inhibitor Antidote


  • A recombinant protein specifically designed to reverse the anticoagulant activity of both direct and indirect Factor Xa inhibitors
  • Being developed as a universal reversal agent for patients anticoagulated with an oral or injectable Factor Xa inhibitor who experience a serious uncontrolled bleeding event or who require urgent or emergent surgery
  • Designated a Breakthrough Therapy by the U.S. Food and Drug Administration
  • Portola has commercial rights to andexanet alfa outside of Japan

Clinical Development

Phase 3b/4

  • Currently being studied in ANNEXA-4, a Phase 3b/4 single-arm, open-label confirmatory study in patients receiving apixaban, rivaroxaban, edoxaban or enoxaparin (a low molecular weight heparin and indirect Factor Xa inhibitor) who present with an acute major bleed.