The FDA Approves Portola Pharmaceuticals’ Andexxa®. The First and ONLY Antidote for the Reversal of Factor Xa Inhibitors

The U.S. Food and Drug Administration (FDA) has approved Portola’s (PTLA) drug Andexxa®, the first and only antidote indicated for patients treated with rivaroxaban and apixaban, when reversal of anticoagulation is needed due to life-threatening or uncontrolled bleeding.

Commenting on the approval, Stuart J. Connolly, M.D., ANNEXA-4 Executive Committee chairman and professor in the Department of Medicine of the Faculty of Health Sciences at McMaster University in Hamilton, Ontario said, “Today’s approval represents a significant step forward in patient care and one that the medical community has been eagerly anticipating. Andexxa’s rapid reversal of the anticoagulation effects of rivaroxaban and apixaban will help clinicians treat life-threatening bleeds, where every minute counts.”

Factor Xa inhibitors’ sales are rapidly growing as they demonstrated several advantages over enoxaparin and warfarin in preventing and treating thromboembolic conditions such as stroke, pulmonary embolism and venous thromboembolism (VTE). However, the sales’ growth has come with a related increase in the incidence of hospital admissions and deaths related to bleeding, the major complication of anticoagulation with no antidote on the market

In the U.S. alone in 2016, there were approximately 117,000 hospital admissions attributable to Factor Xa inhibitor-related bleeding and nearly 2,000 bleeding-related deaths per month.

The approval of Andexxa is supported by data from two Phase 3 ANNEXA studies (ANNEXA-R and ANNEXA-A) published in The New England Journal of Medicine, which evaluated the safety and efficacy of Andexxa in reversing the anticoagulant activity of the Factor Xa inhibitors rivaroxaban and apixaban in healthy volunteers.

The results demonstrated that Andexxa rapidly and significantly reversed anti-Factor Xa activity (the anticoagulant mechanism of these medicines). The median decrease in anti-Factor Xa activity from baseline was 97 percent for rivaroxaban and 92 percent for apixaban.

Patients with Major Bleeding

Interim data from the ongoing ANNEXA-4 single-arm, open-label study in patients with major bleeding from 185 evaluable patients showed that Andexxa rapidly and significantly reversed anti-Factor Xa activity when administered as a bolus and sustained this reversal when followed by a 120-minute infusion. The median decrease from baseline was 90 percent for rivaroxaban and 93 percent for apixaban. The data were also assessed by the FDA as part of its review and approval.  

For additional Important Safety Information and Andexxa’s full Prescribing Information, please visit

The post-marketing requirement is a clinical trial that randomizes patients to receive either Andexxa or usual care (the type of care the enrolling institution would provide in the absence of Andexxa). This study is scheduled to be initiated in 2019 and be reported in 2023.

Consistent with the Company’s prior plan, Portola expects to launch Andexxa under an Early Supply Program with Generation 1 product in early June. A Broader commercial launch is anticipated in early 2019 upon FDA approval of its Generation 2 manufacturing process.

Andexxa is a recombinant protein specifically designed to bind to Factor Xa inhibitors and rapidly reverse their anticoagulant effect. Andexxa works by acting as a decoy for oral and injectable Factor Xa inhibitors, which target and bind to Factor Xa, which allows them to exert their anticoagulant effect. When Andexxa is given to a patient with Factor Xa inhibitor-related bleeding, it binds to the Factor Xa inhibitor and prevents it from inhibiting the activity of Factor Xa and reverses the anticoagulant effects of the inhibitor.

Prohost Observations 

Indeed, the medical community and people on the Factor Xa inhibitors anticoagulants have been eagerly anticipating the approval of the antidote for these important anticoagulant products. We were expecting this approval, yet we waited for it with patience as we recognized the high degree of complexity and difficulty the FDA had to go through before it gives the green light for the use of the first antidote.

The news is extremely important for the doctors, the patients on the Factor Xa inhibitors and definitely for Portola, the first and only company that created and developed this life-saving product.

Now Portola has its two lead products approved. The first, Bevyxxa, is the only Factor Xa inhibitor anticoagulant approved for extended VTE prevention in acute hospitalized medical patients and the second, Andexxa, is the only antidote for Factor Xa inhibitors.

We congratulate Portola and its shareholders as well as the specialists who take care of the patients on anticoagulants and most importantly, the patients who are on Factor Xa inhibitors. They are safer now.

The stock gained over $10 on the news in pre-trading hours.

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