Portola Pharmaceuticals Inc. said a study found that AndexXa reversed blood-thinning activity in patients experiencing acute major bleeding while taking a class of anti-clotting agents known as Factor Xa inhibitors.
Factor Xa plays a key role in the process of coagulation by which blood changes from a liquid to a gel, forming a blood clot.
In a phase 3b/4 trial called Annexa-4, the drug reversed anti-Factor Xa activity, or the anticoagulation mechanism of the inhibitors, when administered all at once as a single dose, or bolus, and sustained this reversal when followed by a 120-minute infusion.
According to interim data from 228 patients, of which 132 were adjudicated for efficacy, 83% of patients achieved excellent or good stoppage of bleeding over a 12-hour period after treatment with AndexXa.
The patients who were confirmed to have major bleeding by the independent adjudication committee and whose anti-Factor Xa activity at the start of the study was substantially elevated saw that AndexXa "rapidly and substantially" reversed such activity. These levels were sustained for the duration of administration.
Portola is developing AndexXa, or andexanet alfa, as a universal antidote for patients receiving an oral or injectable Factor Xa inhibitor, including apixaban and rivaroxaban, who experience a serious uncontrolled or life-threatening bleeding event or who require urgent or emergency surgery. Apixaban is sold by Bristol-Myers Squibb Co. and Pfizer Inc. as Eliquis, while rivaroxaban is sold by Johnson & Johnson and Bayer AG as Xarelto.
Also, the anti-Factor Xa activity fell by a median of greater than 90% for both apixaban and rivaroxaban after the bolus dose, which was sustained at similar levels for the duration of the two-hour infusion.
In the U.S., there were about 117,000 hospital admissions attributable to Factor Xa-related bleeding in 2016 and more than 2,000 bleeding-related deaths per month, according to Portola.
AndexXa is under review by the U.S. Food and Drug Administration, with an assigned action date of May 4, and by the European Medicines Agency, with an expected decision in 2019.
