( SOUTH SAN FRANCISCO July 02 2007 /PR...)Portola Pharmaceuticals Announces Positive Phase II EXPERT Results,and Additional Oral and Poster Presentations at the XXI Congress of,the International Society on Thrombosis and Haemostasis (ISTH),Health

SOUTH SAN FRANCISCO, July 02, 2007 /PRNewswire/ -- Portola Pharmaceuticals, Inc. announced today that it will present clinical and preclinical data on its oral Factor Xa inhibitor and on its intravenous and oral ADP receptor antagonist at the XXI Congress of the International Society of Thrombosis and Haemostasis (ISTH) in Geneva, Switzerland on July 6 through July 12, 2007.

The EXPERT poster, which outlines Phase II data on the Company's lead compound PRT054021, is entitled "Evaluation of the Factor Xa (FXA) Inhibitor, PRT054021 (PRT021), against Enoxaparin in Randomized Trial for the Prevention of Venous Thromboembolic Events after Total Knee Replacement (EXPERT)" and will be featured on July 10, 2007 at 5:30 p.m. CEST in the exhibition area.

    In addition, Portola will make the following presentations:


     "Initial Intravenous Experience with PRT060128 (PRT128), an Orally-

     Available, Direct-Acting, and Reversible P2Y12 Inhibitor," July 10 at

     5:30 p.m. (CEST) in the exhibition area.


     "PRT060128, A Novel, Direct-Acting Orally Available P2Y12 Antagonist,

     Confers Superior Antithrombotic Activity over Clopidogrel in a Mouse

     Thrombosis Model," July 11 at 10:00 a.m. (CEST) in Room Mont Blanc.


     "Differential Effects of Anti-Platelet Drugs on Thrombus Formation and

     Thrombus Stability," July 11, 2007 at 10:45 a.m. (CEST) in Room Mont

     Blanc.


     "Antagonism of Intrinsic Pathway Inhibits Tissue Factor (TF) -- Initiated

     Coagulation in a Platelet-Dependent Whole Blood Flow Assay" July 11 at

     5:30 p.m. (CEST) in the exhibition area.


     "Measurement of Thrombus Stability Predicts Coronary Events Post-

     Percutaneous Coronary Intervention (PCI)" will be presented on July 11 at

     5:30 p.m. (CEST) in the exhibition area.

About PRT054021 -- Portola's Factor Xa Inhibitor

PRT054021 is an oral Factor Xa inhibitor, an a
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