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Portola Pharmaceuticals Announces In Vivo Study Results Demonstrating Andexanet Alfa Significantly Reduced Bleeding and Reversed Anticoagulation Activity of Rivaroxaban While Four-Factor Prothrombin Complex Concentrate Did Not
Andexanet alfa, a
"The finding that andexanet alfa significantly reduced blood loss in an animal model of rivaroxaban bleeding while the PCC showed no reversal activity or improvement in bleeding is consistent with other animal model data from studies conducted by Portola and other labs," said
Dr. Curnutte added, "Four-factor PCCs are
Study Design and Results
The study compared the activity of andexanet alfa to the four-factor PCC in reversing rivaroxaban anticoagulation in an animal model of bleeding, as assessed by blood loss and pharmacodynamic markers of coagulation. Results showed that andexanet alfa significantly reduced blood loss to a level similar to that seen in animals not administered rivaroxaban. Andexanet alfa also significantly and rapidly decreased anti-Factor Xa activity, as well as unbound rivaroxaban, and corrected the prothrombin time. In contrast, therapeutic doses of the PCC had no effect on the rate of blood loss, or on any of the pharmacodynamic markers of coagulation, or on plasma rivaroxaban levels.
|Oral Presentation Details|
Andexanet alfa but not four-factor prothrombin complex concentrate reverses rivaroxaban-induced anticoagulation as measured
by reduction in blood loss in a rabbit liver laceration model (abstract #OR318)
|Presenting Author:||Polly Pine, Ph.D., head of pharmacology, Portola Pharmaceuticals|
|Oral Session Title:||NOACs and Reversal|
|Time and Location:||Wednesday, June 24, 2:30 p.m. ET, Exhibit Hall G & F|
About the Need for a Factor Xa Inhibitor Antidote
Currently, millions of patients are treated with Factor Xa inhibitors for short-term use or chronic conditions, and the anticoagulant market is expected to continue to grow. Recent patient datai confirm earlier clinical trial results showing that, annually, between 1-4 percent of patients treated with Factor Xa inhibitors may experience major bleeding and an additional 1 percent may require emergency surgery. Annually, more than 100,000 U.S. patients are currently impacted and may benefit from an antidote. With the expected increase in adoption of these anticoagulants, Portola projects that this number will increase by the year 2020 to up to 200,000 patients in
About Andexanet Alfa
Andexanet alfa is a modified human Factor Xa molecule that acts as a decoy to target and sequester with high specificity both oral and injectable Factor Xa inhibitors in the blood. Once bound, the Factor Xa inhibitors are unable to bind to and inhibit native Factor Xa, thus allowing for the restoration of normal hemostatic processes. Andexanet alfa has the potential to address numerous clinical scenarios where an antidote is needed by allowing for flexible and controlled reversal. Reversal activity can be short-acting through the administration of an IV bolus or longer-acting with the addition of an extended infusion.
Andexanet alfa is the only compound being studied as a reversal agent for Factor Xa inhibitors that directly and specifically corrects anti-Factor Xa activity – the anticoagulant mechanism of these agents.
Andexanet alfa has been granted orphan drug designation by the
About the Andexanet Alfa Clinical Development Program
Portola is evaluating andexanet alfa in two randomized, placebo-controlled Phase 3 ANNEXA™ (Andexanet Alfa a Novel Antidote to the Anticoagulant Effects of fXA Inhibitors) registration studies using pharmacodynamic endpoints agreed to with the
ANNEXA-4, a Phase 4 single-arm confirmatory study in patients receiving apixaban, rivaroxaban, edoxaban or enoxaparin (a low molecular weight heparin and indirect Factor Xa inhibitor) who present with an acute major bleed is also ongoing.
Data from the ANNEXA-A and ANNEXA-R studies, as well as data from a small number of patients from ANNEXA-4, will serve as the clinical basis of a Biologics License Application (BLA), which Portola plans to submit under an Accelerated Approval pathway.
Results from four separate Phase 2 proof-of concept studies with apixaban, rivaroxaban, edoxaban and enoxaparin in healthy volunteers demonstrated that andexanet alfa immediately reversed the anticoagulation activity of each Factor Xa inhibitor and that the reversal could be sustained. A Phase 2 proof-of-concept study with Portola's investigational Factor Xa inhibitor betrixaban is planned.
Andexanet alfa has been shown to be well tolerated in clinical studies, which have included more than 140 healthy volunteers. No thrombotic events or antibodies to Factor Xa or Factor X have been observed. The most common adverse events have been mild infusion reactions.
Portola's wholly-owned, oral, once-daily Factor Xa inhibitor betrixaban is being evaluated in the only biomarker-based Phase 3 study for hospital-to-home prophylaxis of venous thromboembolism (VTE) in acute medically ill patients. Betrixaban's distinct properties may have the potential to allow the agent to demonstrate efficacy without the significant increase in the rate of major bleeding that was seen in this patient population with other Factor Xa inhibitors. If approved, betrixaban could be the first anticoagulant for both hospital and post-discharge VTE prophylaxis and the standard of care in this large market of more than 20 million patients in the G7 countries alone.
Andexanet alfa, an
Portola's product candidate in the area of hematologic cancer, cerdulatinib, is an orally available molecule that uniquely inhibits two validated tumor proliferation pathways – spleen tyrosine kinase (Syk) and janus kinase (JAK). It is currently being evaluated in a Phase 1/2a proof-of-concept study in patients with B cell leukemias or lymphomas with a focus on genetically-defined subtypes, as well as in patients who have failed therapy due to relapse or acquired mutations.
For more information, visit www.portola.com and follow the Company on Twitter @Portola_Pharma.
Statements contained in this press release regarding matters that are not historical facts are "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995. Because such statements are subject to risks and uncertainties, actual results may differ materially from those expressed or implied by such forward-looking statements. Such statements include, but are not limited to, statements regarding: Portola's plans for future clinical studies and pursuit of an Accelerated Approval process for andexanet alfa, anticipated growth in the market for anticoagulants, the potential indications, efficacy, safety and activity of andexanet alfa, and the potential market and indications for its other product candidates. Risks that contribute to the uncertain nature of the forward-looking statements include: the accuracy of Portola's estimates regarding its ability to initiate and/or complete its clinical trials; the success of Portola's clinical trials and the demonstrated efficacy of Portola's product candidates thereunder; the accuracy of Portola's estimates regarding its expenses and capital requirements; Portola's ability to manufacture andexanet alfa; regulatory developments in
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CONTACT: Investor Contact:
Michele Mantynen Portola Pharmaceuticalsir@portola.com Media Contact: Julie Normart W2O Groupjnormart@w2ogroup.com