Portola Pharmaceuticals Supports “World Thrombosis Day” Campaign

Portola Pharmaceuticals Inc.^® (Nasdaq:PTLA) is committed to raising awareness of the incidence, risks and potentially life-threatening complications of thrombosis (blood clots) and is serving as a global partner for World Thrombosis Day, which is taking place today.
According to the International Society on Thrombosis and Haemostasis (ISTH), 1 in 4 people worldwide dies from conditions related to thrombosis. In the United States alone, up to 900,000 people are affected by blood clots each year and about 100,000 of them die – more than the total number of people who lose their lives each year to AIDS, breast cancer and motor vehicle crashes combined. Thrombosis is the underlying pathology of heart attack, thromboembolic stroke and venous thromboembolism (VTE; a blood clot that forms in a vein and breaks loose and travels in the bloodstream) — the top three cardiovascular killers. In many cases, thrombosis is preventable.
Recent advances in the field of thrombosis have led to the development of novel oral anticoagulants (NOACs) to prevent and treat VTEs. NOACs are predominantly comprised of a class of drugs called Factor Xa inhibitors, which are indicated to prevent stroke and blood clots in people with atrial fibrillation; to treat and prevent deep vein thrombosis (DVT) and pulmonary embolism (PE); and to prevent DVT, which may lead to PE, following hip or knee replacement surgery. In the United States, an estimated 2.5 million people will be treated with a Factor Xa inhibitor this year. The number of patients on Factor Xa inhibitors is currently growing at a rapid rate of approximately 45 percent year-over-year.
Portola is unique in its dedication to helping patients with issues related to thrombosis. It is addressing two significant areas of unmet medical need with its two late-stage product candidates: betrixaban, a Factor Xa inhibitor to prevent blood clots in acute medically ill patients during hospitalization and after discharge, and AndexXa^TM (andexanet alfa), a Factor Xa inhibitor antidote for patients with acute major bleeding.
Patients hospitalized for serious, common medical conditions (i.e., the acute medically ill) are at increased risk for VTE, which is a major cause of morbidity, mortality and re-hospitalization. An estimated 20 million acute medically ill patients in the G7 countries are at risk of developing VTE, either while in the hospital or following discharge. More than half of VTE events among the acute medically ill occur after the patient is discharged from the hospital. Despite the benefits provided by oral Factor Xa inhibitors, none is currently FDA-approved or guideline-recommended for prevention of VTE in acute medically ill patients. Portola is addressing this growing, underserved patient population with its investigational oral Factor Xa inhibitor betrixaban. Betrixaban, an investigational agent, directly inhibits the activity of Factor Xa, an important validated target in the blood coagulation pathway, to prevent life-threatening thrombosis. The Company has conducted a pivotal Phase 3 APEX Study of betrixaban for the prevention of VTE in acute medically ill patients in both the hospital and home setting, and published the results in the New England Journal of Medicine. Portola expects to submit a New Drug Application (NDA) to the U.S. Food and Drug Administration (FDA) for betrixaban before the end of the year.
While Factor Xa inhibitors are effective in preventing blood clots, they can be associated with potentially life-threatening acute major bleeding, including intracranial hemorrhage, in some patients. As the use of Factor Xa inhibitors increases, the number of patients hospitalized each year due to bleeding associated with these agents continues to grow. At this time, no FDA-approved antidote is available and no existing therapies have demonstrated reversal of Factor Xa inhibitor activity or clinical efficacy and safety. Portola is addressing this critical unmet need with its investigational Factor Xa inhibitor antidote, AndexXa. 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. The Company recently reported interim results from its Phase 3b/4 ANNEXA-4 study, which were published in the New England Journal of Medicine, and expects to resubmit a Biologics License Application (BLA) for AndexXa in 2017.

About the Need for an Oral Anticoagulant for Extended-Duration Prevention of VTE in Acute Medically Ill Patients
Acute medically ill patients are 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 serious and potentially life-threatening blood clots known as VTE. An estimated 20 million acute medically ill patients in the G7 countries are at risk of developing VTE, either while in the hospital or following discharge. Each year, more than 1 million VTE events and 150,000 VTE-related deaths occur 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 from the hospital. However, no anticoagulant, including enoxaparin or any of the marketed oral Factor Xa inhibitors, is approved for extended VTE prophylaxis in the more than 24 million medically ill patients hospitalized in the G7 countries annually.

About the Need for a Factor Xa Inhibitor Antidote
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. Commensurate with the increase in the use of Factor Xa inhibitors — for stroke prevention in atrial fibrillation; treatment and prevention of deep vein thrombosis (DVT) and pulmonary embolism; and prevention of DVT following knee or hip replacement surgery — the number of hospital admissions due to bleeding associated with these agents continues to grow. In the United States, more than 80,000 patients treated with oral Factor Xa inhibitors were admitted to the hospital due to bleeding during 2015. Including patients taking the injectable Factor Xa inhibitor enoxaparin, it is estimated that more than 100,000 U.S. patients could benefit from an antidote annually.
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 and estimated timelines associated therewith. 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 product approvals, and the risk that the results from our APEX clinical trial may cause betrixaban regulatory approval to be delayed, more costly or not be obtained at all, 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 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
ir@portola.com
Media Contact:
Julie Normart
W2O Group
jnormart@w2ogroup.com
415.946.1087