Results to be presented on Thursday, February 7, 2019 at 11:36 a.m. HST/4:36 p.m. EST

SOUTH SAN FRANCISCO, Calif., Jan. 30, 2019 (GLOBE NEWSWIRE) — Portola Pharmaceuticals, Inc.^® (Nasdaq: PTLA) today announced that full results from the Company’s ANNEXA-4 study of Andexxa^® [coagulation factor Xa (recombinant), inactivated-zhzo] have been accepted as a late-breaking oral presentation during the International Stroke Conference (ISC) 2019. The data will be presented on Thursday, February 7, 2019 at 11:36 a.m. Hawaii Standard Time and has also been submitted for simultaneous publication in a peer-reviewed medical journal.

Andexxa received both U.S. Orphan Drug and U.S. Food and Drug Administration (FDA) Breakthrough Therapy designations, and was approved on May 3, 2018 under the FDA’s Accelerated Approval pathway. It is the first and only antidote indicated for patients treated with rivaroxaban or apixaban, when reversal of anticoagulation is needed due to life-threatening or uncontrolled bleeding.

Oral Presentation Title: Andexanet Alfa for Treatment of Factor Xa Inhibitor-Related Acute Major Bleeding

• Session Title: Thursday Main Event
• Session Number: ME II
• Presenter: Truman J. Milling Jr., M.D., FACEP, Seton Dell Medical School Stroke Institution
• Presentation Date and Time: Thursday, February 7, 2019 at 11:36 a.m. HST
• Location: Hawaii Convention Center, Hall III

About Portola Pharmaceuticals, Inc.
Portola Pharmaceuticals is a commercial-stage biopharmaceutical company focused on the discovery, development and commercialization of novel therapeutics that could significantly advance the fields of thrombosis and other hematologic diseases. The Company’s two FDA-approved medicines are Andexxa^® [coagulation factor Xa (recombinant), inactivated-zhzo], the first and only antidote for patients treated with rivaroxaban and apixaban when reversal of anticoagulation is needed due to life-threatening or uncontrolled bleeding, and Bevyxxa^® (betrixaban), the first and only oral, once-daily Factor Xa inhibitor for the prevention of VTE in adult patients hospitalized for an acute medical illness. The company also is advancing cerdulatinib, a Syk/JAK inhibitor for the treatment of hematologic cancers.

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, Andexxa’s potential to address life-threatening bleeding associated with the use of the Factor Xa inhibitors apixaban or rivaroxaban. Risks that contribute to the uncertain nature of the forward-looking statements include: the risk that physicians, patients and payers may not see the benefits of utilizing Andexxa or Bevyxxa for the indications which they are approved; our ability to continue to manufacture our products and to expand approved manufacturing facilities; the possibility of unfavorable results from additional clinical trials involving Andexxa; the risk that the EMA may not approve Andexxa in the currently anticipated timelines or at all, and that any marketing approvals or reimbursement limitations may have significant limitations on its use; the risk that we may not obtain additional regulatory approvals necessary to expand approved indications for Andexxa; 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 expenses and capital requirements; our ability to successfully build a hospital-based sales force and commercial infrastructure; 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. 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.