Andexanet alfa: Rapid reversal of Factor Xa inhibitors

M. Khurram Afzal, M.D.
By M. Khurram Afzal, M.D. on

On Monday, March 12th at ACC 2018 in Orlando, Florida, an interim analysis from the ongoing ANNEXA-4 study demonstrated that the first- in-class reversal drug for direct and indirect factor Xa inhibitors, Andexanet alfa, was able to effectively reverse the anti-factor Xa activity and control major bleeding events among patients taking one of four Factor Xa inhibitors (apixaban, rivaroxaban, edoxaban or enoxaparin).

Stuart Connolly, MD reported the occurrence of the two primary efficacy endpoints: % of patients with bleeding control within 12 hours following the administration of andexanet alfa  and reduction in Anti-Factor Xa inhibitor activity. The safety endpoint were the rates of 30-day mortality and thrombotic events. This prospective, multicenter single arm cohort of 227 patients with active major bleeding  within 18 hours of taking a Factor Xa demonstrated the efficacy of andexanet alfa to stop the bleeding events : 83% of the patients at 12 hours (CI = 0.75-0.89). Moreover, there was a 88% median reduction in anti-factor Xa inhibitor activity among patients taking rivaroxaban, 91% with apixaban and 75% with enoxaparin.

The 30-day mortality was 12% and the rate of thrombotic events was 2.6% and 11% at 3 days and 30 days respectively.

After the first preliminary report of the ANNEXA study published in the NEJM, this new analysis suggest  both safety and efficacy of Andexanet alfa to reverse the effect of Factor Xa inhibitor.

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