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Treatment for Reversal of Anticoagulant Activity of Factor Xa Inhibitors

Portola Pharmaceuticals Completes BLA Submission to U.S. Food and Drug Administration for Andexanet Alfa

SOUTH SAN FRANCISCO, Calif., Dec. 18, 2015 (GLOBE NEWSWIRE) -- Portola Pharmaceuticals, Inc. (Nasdaq:PTLA) announced today completion of the submission of a Biologics License Application (BLA) to the U.S. Food and Drug Administration (FDA) for its investigational agent andexanet alfa, an FDA-designated breakthrough therapy specifically designed to reverse the anticoagulant activity of both direct and indirect Factor Xa inhibitors. Portola is developing andexanet alfa as a universal reversal agent for patients anticoagulated with an oral or injectable Factor Xa inhibitor who experience a serious uncontrolled bleeding event or who require urgent or emergency surgery.

The BLA submission includes data from Portola’s Phase 3 ANNEXA™ (Andexanet Alfa a Novel Antidote to the Anticoagulant Effects of FXa Inhibitors) studies, which evaluated the safety and efficacy of andexanet alfa in reversing the anticoagulant activity of the Factor Xa inhibitors rivaroxaban and apixaban, respectively, in healthy volunteers. Results of those studies were published online by The New England Journal of Medicine in November 2015. In addition, data from a small number of patients from ANNEXA-4 will serve as the clinical basis for the BLA. Portola is currently evaluating andexanet alfa in this global Phase 4 single-arm, open-label 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.

About the Need for a Factor Xa Inhibitor Reversal Agent

Commensurate with the increase in use of Factor Xa inhibitors, the number of hospital admissions due to bleeding associated with these agents continues to grow. Annually, 1 to 4 percent of patients treated with Factor Xa inhibitors may experience major bleeding, and an additional 1 percent may require emergency surgery. In the United States alone, during the 12 months ended April 2015, there were over 50,000 rivaroxaban or apixaban treated patients admitted to the hospital due to bleeding.1 This number does not account for patients taking the injectable Factor Xa inhibitor enoxaparin or those on a Factor Xa inhibitor undergoing emergency surgery. In the United States, more than 100,000 patients annually may benefit from a reversal agent. Currently, there is no FDA-approved reversal agent for Factor Xa inhibitors for these patients.

About Andexanet Alfa

Andexanet alfa, an investigational drug, 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 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.

About Portola Pharmaceuticals, Inc.

Portola Pharmaceuticals is a biopharmaceutical company developing product candidates that could significantly advance the fields of thrombosis and other hematologic diseases. The Company is advancing its three wholly-owned programs using novel biomarker and genetic approaches that may increase the likelihood of clinical, regulatory and commercial success of its potentially life-saving therapies. These programs include betrixaban, an oral, once-daily Factor Xa inhibitor being evaluated in the APEX Phase 3 study for prophylaxis of venous thromboembolism; andexanet alfa, a recombinant protein designed to reverse the anticoagulant effect in patients treated with an oral or injectable Factor Xa inhibitor; and cerdulatinib, a Syk/JAK inhibitor in development to treat hematologic cancers. Portola's partnered program is focused on developing selective Syk inhibitors for inflammatory conditions. For more information, visit and follow the Company on Twitter @Portola_Pharma.

Forward-looking Statements

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: andexanet alfa’s potential to treat patients needing reversal of Factor Xa anticoagulation effects, the projected number of patients that could benefit from andexanet alfa, the potential for andexanet alfa to become the first universal reversal agent for Factor Xa inhibitors and the standard of care for managing major bleeding among patients on Factor Xa inhibitors, our plans for pursuit of regulatory approval of andexanet alfa, and the likelihood of clinical, regulatory and commercial success for andexanet alfa and our other product candidates. Risks that contribute to the uncertain nature of the forward-looking statements include: our expectation that we will incur losses for the foreseeable future and will need additional funds to finance our operations; the accuracy of our estimates regarding our ability to initiate and/or complete our clinical trials and the timing and expense of these trials; the pace of enrollment in our clinical trials; the results of our clinical trials related to the efficacy and safety of our product candidates; the risk that regulatory approval of our product candidates may not be received in a timely manner, or at all; our potential inability to manufacture andexanet alfa and our other product candidates on a commercial scale in a timely or cost-efficient manner; the accuracy of estimates regarding our expenses and capital requirements; our ability to successfully build a hospital-based sales force and commercial infrastructure; regulatory developments in the United States and foreign countries; our ability to obtain and maintain intellectual property protection for our product candidates; and our ability to retain key scientific or management personnel. These and other risks and uncertainties are described more fully in our most recent filings with the Securities and Exchange Commission, including our Annual Report on Form 10-K, which was filed on March 2, 2015, and Quarterly Report on Form 10-Q for the third quarter of 2015, which was filed on November 9, 2015. All forward-looking statements contained in this press release speak only as of the date on which they were made. We undertake no obligation to update such statements to reflect events that occur or circumstances that exist after the date on which they were made.

1 Truven, MarketScan Commercial, Medicare Supplemental, last 12 months ending April 30, 2015. Medicaid accounts for ~5% of the total bleed-related admissions.

Source: Portola Pharmaceuticals, Inc.

Posted: December 2015

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