US-based biopharmaceutical company Portola has reported positive interim results from its ongoing Phase IIIb/IV ANNEXA-4 study of AndexXa to treat Factor Xa inhibitor-associated acute major bleeding.

AndexXa is developed as a modified human Factor Xa molecule, which poses as a decoy to the target and isolates both oral and injectable Factor Xa inhibitors in the blood.

After the bond, the Factor Xa inhibitors are unable to bind to and prevent native Factor Xa, thereby allowing the restoration of normal hemostatic processes that refer to the stoppage of bleeding.

Factor Xa inhibitors are considered functional to decrease the risk of intracranial hemorrhage.

"The ANNEXA-4 trial is designed as a global, single-arm, open-label, multi-centre cohort study intended to test AndexXa."

The ANNEXA-4 trial is designed as a global, single-arm, open-label, multi-centre cohort study intended to test AndexXa.

It enrolled more than 130 patients experiencing acute major bleed when administered with apixaban, rivaroxaban, edoxaban or enoxaparin.

All patients were administered with AndexXa as a bolus dose more than 30 minutes after two hours infusion.

The co-primary goal of the study was to detect the change in anti-Factor Xa activity at two hours and examining the hemostasis over 12 hours after the infusion.

Analysis of an interim data of 67 patients suggested the efficacy of AndexXa in rapidly reversing the anti-Factor Xa activity, which sustained after a two hours infusion.

It is reported 79% of these patients have experienced favourable hemostasis.

McMaster University department of medicine of the faculty of health sciences professor and ANNEXA-4 executive committee chairman Stuart Connolly said: “In this preliminary analysis, AndexXa was effective in rapidly reversing anti-Factor Xa inhibitor activity and restoring normal blood clotting in real-world patients with Factor Xa inhibitor-related bleeding.

“Based on these interim results, we believe that ANNEXA-4 is on track to achieve its co-primary efficacy endpoints upon study completion.

“The hemostatic efficacy results are especially important because no FDA or EMA-approved antidote is available for these patients and no existing therapies, including plasma-derived products for warfarin reversal, have demonstrated reversal of Factor Xa inhibitor activity or clinical efficacy and safety.”