Portola Pharmaceuticals Announces Betrixaban and AndexXa™ (andexanet alfa) Presentations at ACC.17

Portola Pharmaceuticals Inc.® (Nasdaq:PTLA) today announced that new data from the pivotal Phase 3 APEX Study of the Company’s investigational drug betrixaban will be presented in a poster session at the upcoming American College of Cardiology’s (ACC) 66th Annual Scientific Session & Expo, which is taking place from March 17-19 at the Walter E. Washington Convention Center in Washington, D.C. Additionally, clinical data on betrixaban and on the Company’s investigational agent AndexXa™ (andexanet alfa) will be discussed during an oral session titled, “Challenging the Standard of Care: Emerging Concepts in VTE Treatment and Prevention.”

Betrixaban, which has Fast Track designation from the U.S. Food and Drug Administration (FDA), is an oral, once-daily Factor Xa inhibitor anticoagulant in development for the extended prophylaxis of venous thromboembolism (VTE) in acute medically ill patients with risk factors for VTE. AndexXa, a U.S. Food and Drug Administration (FDA)-designated Breakthrough Therapy, 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.

The betrixaban poster will include additional data that is not available in the abstract, which is currently available on the ACC website.

Betrixaban

• Abstract Title: Extended Duration Betrixaban Reduces the Risk of Venous Thromboembolism Versus Standard Duration Enoxaparin in the Post Parenteral Period Among Hospitalized Medically Ill PatientsPoster #: 055Presenting Author: Serge Korjian, M.D., Beth Israel Deaconess Medical Center, Boston Session Title: Diabetes and Other Issues in Cardiovascular Prevention Presentation Date and Time: Sunday, March 19, 9:45-10:30 a.m. ETPresentation Location: Poster Hall, Hall C

• Presentation Title: Extended Pharmacological Thromboprophylaxis at Hospital Discharge for High Risk Medical PatientsPresenting Author: Alexander (Ander) T. Cohen, MBBS, M.Sc., M.D., FRACP, APEX Co-Principal Investigator and Co-Chairman of the APEX Executive Committee and consultant physician at Guy’s and St Thomas’ NHS Foundation TrustSession Title: Challenging the Standard of Care: Emerging Concepts in VTE Treatment and PreventionSession Number: 637Presentation Date and Time: Friday, March 17, 2:48-3:00 p.m. ETPresentation Location: Room 209 C

AndexXa™ (andexanet alfa)

• Presentation Title: Managing Life-threatening Bleeding in Patients Taking Non-Vitamin K Oral Anticoagulants: When and How to Use Reversal AgentsPresenting Author: Samuel Goldhaber, M.D., senior physician, Brigham and Women’s Hospital, Boston  Session Title: Challenging the Standard of Care: Emerging Concepts in VTE Treatment and PreventionSession Number: 637Presentation Date and Time: Friday, March 17, 2:24-2:36 p.m. ETPresentation Location: Room 209 C

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

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