Portola Pharmaceuticals Announces Several Scientific Presentations at International...

Portola Pharmaceuticals Announces Several Scientific Presentations at
International Society on Thrombosis and Haemostasis XII Congress

SOUTH SAN FRANCISCO, Calif., July 10 /PRNewswire/ -- Portola Pharmaceuticals,
Inc. today announced several scientific presentations at the International
Society on Thrombosis and Haemostasis (ISTH) XII Congress in Boston that will
feature its investigational antiplatelet drug elinogrel, a P2Y(12) ADP
receptor antagonist currently in Phase II clinical development, and its oral
Factor Xa inhibitor anticoagulant antidote in pre-clinical development, as
well as a presentation by Portola co-founder David Phillips on new directions
in antithrombotic drug discovery.

In the past six months, Portola has announced global development and
commercialization agreements with Novartis for elinogrel and with Merck & Co.,
Inc. for betrixaban, an investigational oral Factor Xa inhibitor anticoagulant
currently in Phase II clinical development.

Scientific Presentations
A Functional Pool of P2Y12 Receptors Exposed Upon Platelet Activation Persists
in Mice Treated with High Dose Clopidogrel, and Can Be Blocked by Elinogrel, a
Direct Acting Reversible P2Y12 Inhibitor (Presentation #PP-MO-045)
Presenter: Helena Haberstock-Debic
Date: Monday, July 13, 12:30-2:15 p.m.
Location: Poster Area, Platelet Biology

New Directions in Antithrombotic Drug Discovery: Pharmacological Uncoupling
of Arterial thrombosis from Hemostasis (Presentation #AS-TU-026)
Presenter: David Phillips
Date: Tuesday, July 14, 1:15-1:45 p.m.
Location: Room 104 ABC, Platelets and Systemic Disorders

The Antiplatelet Effect of a New, Direct Acting, Reversible P2Y12 Inhibitor,
Elinogrel (PRT060128) in Patients with High Platelet Reactivity During
Clopidogrel Therapy (Presentation #PP-WE-801)
Presenter: Paul Gurbel
Date: Wednesday, July 15, 12:30-2:15 p.m.
Location: Poster Area, Patient Oriented Studies of Antiplatelet Therapy

ADP-Mediated Aggregation as a Pharmacodynamic Assay Underestimates the
Antithrombotic Activity of Elinogrel, a Competitive, Reversible P2Y12
Inhibitor, Relative to Clopidogrel (Presentation #PP-TH-027)
Presenter: Pamela Conley
Date: Thursday, July 16, 12:30-2:15 p.m.
Location: Poster Area, Platelet Biology

Clopidogrel and Prasugrel Prolong Primary Hemostasis in the Mouse Beyond
Levels Associated with P2Y12 Inhibition (Presentation #AS-TH-022)
Presenter: Patrick Andre
Date: Thursday, July 16, 2:15-3:45 p.m.
Location: 157 ABC Oral, Platelets as Drug Targets

Reconstructed Recombinant Factor Xa as an Antidote to Reverse Anticoagulation
by Factor Xa Inhibitors (Presentation #OC-TH-107)
Presenter: Genmin Lu
Date: Thursday, July 16, 4:00-5:00 p.m.
Location: 102 AB Oral, Inhibitors of Coagulation and Fibrinolysis

About Portola Pharmaceuticals, Inc.
Portola Pharmaceuticals develops innovative therapeutics based on targets with
established proof of concepts that are designed to provide significant
advances over current treatments for cardiovascular disease, inflammatory
disease and cancer. The company has global development and commercialization
agreements with two of the world's leading pharmaceutical companies
collectively valued at about $1B in upfront and milestone payments plus
escalating double-digit royalties on future sales. Betrixaban, its oral
Factor Xa inhibitor is licensed to Merck & Co., Inc., and elinogrel, its
P2Y(12) ADP receptor antagonist and potential competitor for Plavix*
(clopidogrel), is licensed to Novartis. Both betrixaban and elinogrel are
Phase II product candidates that have best-in-class features to address the
global multi-billion hospital, specialty, and chronic care anticoagulant and
antiplatelet markets, respectively.

Portola also has proprietary pipeline programs focused on the discovery and
development of novel, specific Syk and JAK inhibitors to treat cancer and
inflammatory diseases; a thromboxane receptor antagonist, which is an aspirin
replacement product for patients intolerant to aspirin; and a novel
anticoagulant antidote program with the potential to help manage or reverse
the bleeding complications in the tens of millions of patients expected to be
treated with anticoagulants worldwide in the next decade. For additional
information, visit www.portola.com.

* Plavix(R) is a registered trademark of Sanofi/Aventis and Bristol Myers
Squibb.

SOURCE Portola Pharmaceuticals, Inc.

Mardi Dier, CFO of Portola Pharmaceuticals, +1-650-246-7236; or Mariesa Kemble
of Invigorate Communications, +1-608-850-4745, for Portola Pharmaceuticals