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VIDEO: Andexanet alfa effectively reverses factor Xa anticoagulant

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Andexanet alfa will boost factor Xa inhibitor use

Treatment with andexanet alfa produced good or excellent hemostasis in 83% of patients in the ANNEXA-4 study, which is what matters when patients are bleeding. Clinicians want to know that you can restore coagulation to a level where you can stop bleeding, and that’s what the results show.

The lack of a reversal agent until now for direct-acting factor Xa inhibitor drugs has probably been a modest but real obstacle to widespread adoption of these agents. We can look at the example of another new oral anticoagulant, dabigatran (Pradaxa), which works by a different mechanism, specifically by inhibiting thrombin. After a reversal agent for dabigatran, idarucizumab (Praxbind) received Food and Drug Administration approval and became available in late 2015, an uptick in dabigatran prescriptions occurred. That experience shows that patients and providers want the safety net of a reversal agent. They want to know that, if there is bleeding or need for urgent surgery, there is a way to facilitate restoration of hemostasis.

It’s the same with direct factor Xa inhibitors: Some patients are concerned about the lack of a reversal agent, and having such an agent may help increase access to these agents for such patients. I think that, once andexanet becomes available for routine U.S. practice, we’ll see an uptick in prescribing of direct factor Xa inhibitors. Also, some patients who have opted for treatment with warfarin will switch to a safer class of drugs, the direct factor X a inhibitors. A myth exists that reversal agents can easily negate the anticoagulant effect of warfarin. The reality is that, despite having treatments that reverse warfarin’s effect, this is often not an easy process in actual practice.

On the safety side, there was no indication in the ANNEXA-4 results of rebound thrombosis with andexanet alfa treatment. Patients receiving a direct factor Xa inhibitor are prothrombotic – that’s why they are on an anticoagulant – so their risk for a thrombotic event is always there, especially when they are not fully anticoagulated, such as when a reversal agent is administered. We need to look to restarting treatment with an anticoagulant because these patients have a high thrombotic risk.

Gregory Piazza, MD , is a cardiologist at Brigham and Women’s Hospital in Boston. He has been an advisor to Portola Pharmaceuticals, the company developing andexanet alfa, as well as to Bayer and Pfizer, and he has received research funding from Bristol-Myers Squibb, Janssen, and Daiichi Sankyo. He made these comments in an interview .



Adjudicated efficacy results were available for 132 patients and showed good or excellent hemostasis achieved on andexanet in 109 patients (83%), Dr. Connolly reported. The effect on hemostasis was consistent regardless of patient age, sex, bleeding site, type of anticoagulant, and dosage tested.

Thrombotic events during the 30 days following treatment occurred in 24 of 227 patients (11%) who received andexanet and were evaluable for safety. Notably, no clustering of thrombotic events occurred early, even among the 129 patients who restarted on an anticoagulant during the 30 days after treatment. Among the 129 patients who restarted on an anticoagulant, 9 (7%) had a thrombotic event during the 30-day follow-up, compared with 15 events among 98 patients (15%) who did not restart on an anticoagulant.

Dr. Connolly acknowledged that a limitation of the ANNEXA-4 study is the absence of a control group, but he added that he and his associates believed randomizing patients with a serious bleed to placebo control would not have been “practical, feasible, or ethical.”

ANNEXA-4 is sponsored by Portola Pharmaceuticals, the company developing andexanet alfa (AndexXa). Dr. Connolly has been a consultant to Portola, and also to Bayer, Boehringer-Ingelheim, Bristol-Myers Squibb, and Sanofi-Aventis. Dr. Kirtane has received research support from several device manufacturers.

SOURCE: Connolly S. ACC 2018.


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