Portola Pharmaceuticals to Present Preclinical Data with Andexanet Alfa and Factor Xa Inhibitor Edoxaban at European Society of Cardiology Congress 2015

SOUTH SAN FRANCISCO, Aug. 27, 2015 (GLOBE NEWSWIRE) — Portola Pharmaceuticals (Nasdaq: PTLA) today announced that results of a preclinical study of andexanet alfa will be presented in a moderated poster session at the European Society of Cardiology (ESC) 2015 Congress in London, U.K. The study assessed the activity of andexanet alfa in reversing anticoagulation and reducing bleeding in a validated animal model using Daiichi Sankyo’s oral, once-daily, direct Factor Xa inhibitor edoxaban as the anticoagulant.

Andexanet alfa, a U.S. Food and Drug Administration (FDA)-designated breakthrough therapy, is a recombinant protein specifically designed to reverse the anticoagulant activity of Factor Xa inhibitors. Portola is developing andexanet alfa as a universal antidote for patients anticoagulated with an oral or injectable Factor Xa inhibitor who suffer a major bleeding episode or require emergency surgery.

Portola previously conducted a successful Phase 2 proof-of concept study to evaluate andexanet alfa as an antidote for edoxaban in healthy volunteers. Portola is currently evaluating the antidote in two randomized, placebo-controlled Phase 3 ANNEXA™ registration studies with apixaban and rivaroxaban and in a Phase 4 confirmatory study in patients receiving apixaban, rivaroxaban, edoxaban or enoxaparin who present with an acute major bleed. The Company expects to submit a Biologics License Application (BLA) for andexanet alfa to the FDA under an Accelerated Approval pathway at the end of 2015.

Details of the moderated poster presentation follow.

Abstract Title: Andexanet alfa reverses edoxaban-induced anticoagulation in a rabbit 
  liver laceration model of acute bleeding (poster #P3088)
Presenting Author:  Polly Pine, Ph.D., senior director of pharmacology, Portola 
  Pharmaceuticals
Session Title Moderated Posters: Ischaemia, experimental studies
Presentation Date,  Monday, August 31, 10:51 a.m. BST at ExCel London, Poster Area, 
Time and Location:  Moderated Poster Station

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.

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 FDA for reversing the anticoagulant effect of direct or indirect Factor Xa inhibitors in patients experiencing a serious uncontrolled bleeding event or who require urgent or emergent surgery.

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 www.portola.com and follow the Company on Twitter @Portola_Pharma.

Forward-looking Statement

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 and the likelihood of clinical, regulatory and commercial success for andexanet alfa and 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 the United States and foreign countries; Portola’s ability to obtain and maintain intellectual property protection for its product candidates; and the loss of key scientific or management personnel. These and other risks and uncertainties are described more fully in Portola’s most recent filings with the Securities and Exchange Commission, including its Annual Report on Form 10-K, which was filed on March 2, 2015, and Quarterly Report on Form 10-Q, which was filed on August 5, 2015. All forward-looking statements contained in this press release speak only as of the date on which they were made. Portola undertakes no obligation to update such statements to reflect events that occur or circumstances that exist after the date on which they were made.

CONTACT: Investor Contact:	
         Michele Mantynen 	
         Portola Pharmaceuticals 
         ir@portola.com 	

         Media Contact:	
         Julie Normart		
         W2O Group 
         jnormart@w2ogroup.com

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