Portola Pharmaceuticals Announces Presentation of Interim Results from Phase 3b/4 ANNEXA™-4 Study of AndexXa™ (andexanet alfa) at European Society of Cardiology 2016 Congress

SOUTH SAN FRANCISCO, Calif., Aug. 26, 2016 -- Portola Pharmaceuticals Inc.^® (Nasdaq:PTLA) today announced that interim results from its ongoing Phase 3b/4 ANNEXA™-4 trial of AndexXa™ (andexanet alfa), a Factor Xa inhibitor antidote, will be featured in an oral Late-Breaking Science Hot Line session at the European Society of Cardiology (ESC) 2016 Congress, which will take place from August 27–31 in Rome. The data also will be featured in the ESC’s Hot Line – Preventive Strategies II press conference on Tuesday, August 30, at 9:00 a.m. CEST.

Portola will host an investor event, which will be webcast, on Tuesday, August 30, at 5:00 p.m. CEST, following the ANNEXA-4 interim results presentation at the ESC Congress. Members of Portola’s senior management team, together with Dr. Stuart J. Connolly, ANNEXA-4 Executive Committee chairman, and Dr. C. Michael Gibson, ANNEXA-4 Executive Committee member, will present and discuss the data.

Following are details of the oral presentation, which will include additional data not available in the posted abstract.

Abstract Title: ANNEXA-4 – Andexanet alfa for reversal of Factor Xa inhibitors in patients with acute major bleeding
Presenting Author: Stuart J. Connolly, M.D., professor, Department of Medicine, Faculty of Health Sciences, McMaster University, Hamilton, Ontario
Session Title: Hot Line Preventive Strategies, 2
Presentation Date and Time: Tuesday, August 30, 2:18–2:36 p.m. CEST
Location: Fiera di Roma Exhibition and Trade Centre, Rome – Main Auditorium

Investor Event Webcast Information

The investor event will take place from 5:00-6:00 p.m. CEST/11 a.m.-12 p.m. EDT on Tuesday, August 30, and will be simultaneously webcast. To access the live and subsequently archived webcast, go to the Investor Relations section of the company's website at http://investors.portola.com. A replay will be available for 30 days following the live event.

About AndexXa
AndexXa, 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 potentially allowing for the restoration of normal hemostatic processes. AndexXa is the first compound being studied as an antidote for Factor Xa inhibitors that directly and specifically reverses anti-Factor Xa activity – the anticoagulant mechanism of these agents.

A U.S. Food and Drug Administration (FDA)-designated Breakthrough Therapy, AndexXa is in development for patients treated with a direct (apixaban, rivaroxaban, or edoxaban) or indirect (enoxaparin) Factor Xa inhibitor when reversal of anticoagulation is needed due to life-threatening or uncontrolled bleeding. On August 17, 2016, Portola received a Complete Response Letter (CRL) from the FDA regarding its Biologics License Application (BLA) for AndexXa. The Company plans to meet with the FDA as soon as possible in order to resolve the outstanding questions in the CRL and determine appropriate next steps.

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 three programs, including betrixaban, an oral, once-daily Factor Xa inhibitor; AndexXa™ (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 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 the potential future regulatory approval of andexanet alfa and patient populations that could benefit from a Factor Xa inhibitor reversal agent. Risks that contribute to the uncertain nature of the forward-looking statements include the risk that we may be unable to satisfy regulatory requirements for such approval, we may be unable to manufacture andexanet alfa on a commercial scale and we will need additional capital to fund our operations. These and other risks and uncertainties are described more fully in our most recent filings with the Securities and Exchange Commission, including our Current Report on 8-K filed on August 19, 2016, and our most recent quarterly report on Form 10-Q, which was filed on August 9, 2016. 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.

Investor Contact:
Ana Kapor
Portola Pharmaceuticals
[email protected]

Media Contact:
Julie Normart
W2O Group
[email protected]
415.946.1087