$PTLA #FDA #NDA, #EMA Validation #Betrixaban

SOUTH SAN FRANCISCO, Calif., Dec. 23, 2016  — Portola Pharmaceuticals, Inc.^® (Nasdaq:PTLA) today announced that the U.S. Food and Drug Administration (FDA) accepted Portola’s New Drug Application (NDA) granting priority review for betrixaban, an oral, once-daily Factor Xa inhibitor anticoagulant, for extended-duration prophylaxis of venous thromboembolism (VTE) in acute medically ill patients with risk factors for VTE. A priority review shortens the FDA review timeline to six months from the standard review period of 10 months. The application for betrixaban, an FDA-designated Fast Track investigational drug, was deemed sufficiently complete to permit a substantive review and has been given a Prescription Drug User Fee Act (PDUFA) action date of June 24, 2017.

Additionally, Portola announced that the European Medicines Agency (EMA) has validated its Marketing Authorization Application (MAA) for betrixaban for extended-duration prophylaxis of VTE in adults with acute medical illness and risk factors for VTE. The EMA’s Committee for Medicinal Products for Human Use (CHMP) is reviewing the application under a standard 210-day review period.

“With the filing of the betrixaban NDA and the MAA validation, we now look forward to working with the FDA and EMA to bring this drug to market,” said Bill Lis, chief executive officer of Portola. “Betrixaban has the potential to be the first anticoagulant approved for in-hospital and extended-duration VTE prophylaxis in high-risk acute medically ill patients.”

The NDA and MAA for betrixaban are supported by data from Portola’s pivotal Phase 3 APEX Study, which enrolled 7,513 patients at more than 450 clinical sites worldwide and assessed the superiority of extended-duration anticoagulation with oral betrixaban for 35-42 days compared with standard-duration injectable enoxaparin for 10+4 days in preventing VTE in high-risk acute medically ill patients. Full results from the multicenter, randomized, active-controlled APEX Study were presented at the 62^nd Annual International Society on Thrombosis and Haemostasis (ISTH) Scientific and Standardization Committee (SSC) Meeting in May 2016 and published online in The New England Journal of Medicine in May 2016.ⁱ Results from three sub-studies of the APEX Study, including a retrospective sub-study that assessed the potential of extended-duration thromboprophylaxis with betrixaban to reduce the risk of stroke in hospitalized acute medically ill patients, were presented at the American Heart Association (AHA) Scientific Sessions in November 2016 and published in Circulation.ⁱⁱ

About VTE in Acute Medically Ill Patients

Acute medically ill patients are those hospitalized for serious, common medical conditions, including heart failure, stroke, infection and pulmonary disease. Because of their underlying disorder or immobilization during hospitalization, they are at increased risk of VTE, a serious and potentially life-threatening blood clot (thrombus). VTE, which includes both deep vein thrombosis (DVT) and pulmonary embolism (PE), is a major cause of preventable morbidity and mortality and re-hospitalization in the acute medically ill patient population.

In the G7 countries, an estimated 24 million acute medically ill patients are hospitalized each year and are at risk of VTE, either while in the hospital or following discharge. More than 1 million VTE events and 150,000 VTE-related deaths occur annually in acute medically ill patients in the G7 countries, despite the standard use of injectable enoxaparin and other heparins in the hospital. More than half of VTE events occur after the patient is discharged. However, no anticoagulant, including enoxaparin or any of the marketed oral Factor Xa inhibitors, is approved for in-hospital and extended-duration VTE prophylaxis in acute medically ill patients who are hospitalized.

About Betrixaban

Betrixaban, an investigational drug, directly inhibits the activity of Factor Xa, an important validated target in the blood coagulation pathway, to prevent life-threatening thrombosis. Betrixaban has distinct properties that may allow it to demonstrate clinical benefit without the significant imbalance in the risk of major bleeding seen with other agents in the class. These include a 19-25-hour half-life for once-daily dosing; a low peak-to-trough drug concentration ratio that minimizes anticoagulant variability; low renal clearance; and no significant CYP3A4 metabolism, which may reduce the risk of drug-drug interactions.

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 development of our product candidates, our regulatory applications and estimated timelines associated therewith. Risks that contribute to the uncertain nature of the forward-looking statements include: failure to obtain regulatory approval for one or more of our product candidates, our expectation that we will incur losses for the foreseeable future and will need additional funds to finance our operations; the results of our clinical trials related to the efficacy and safety of our product candidates; our potential inability to manufacture our product candidates on a commercial scale in a timely or cost-efficient manner; the accuracy of our estimates regarding expenses and capital requirements; 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 most recent quarterly report on Form 10-Q, which was filed on November 7, 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.

ⁱ Cohen AT, Harrington RA, Goldhaber SZ, Hull RD, Wiens BL, et al. Extended thromboprophylaxis with betrixaban in acutely ill medical patients. N Engl J Med. 2016;375:534-544.

ⁱⁱ Gibson CM, Chi G, Halaby R, Korjian S, Daaboul Y, et al. Extended-Duration Betrixaban Reduces the Risk of Stroke Versus Standard-Dose Enoxaparin Among Hospitalized Medically Ill Patients: An APEX Trial Substudy (Acute Medically Ill Venous Thromboembolism Prevention With Extended Duration Betrixaban). Circulation. https://doi.org/10.1161/CIRCULATIONAHA.116.025427.

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