( NEW ORLEANS March 28 2007 /PRNewswir...)Portola Pharmaceuticals Presents Positive Phase I Data of Its ADP,Receptor Antagonist at the American College of Cardiology,Health

NEW ORLEANS, March 28, 2007 /PRNewswire/ -- Portola Pharmaceuticals, Inc. presented Phase I data of its ADP receptor antagonist at the of Cardiology's (ACC) 56th Annual Scientific Session this week. Portola's reversible antiplatelet compound, PRT060128, appeared safe and well-tolerated in this study and achieved high-level platelet inhibition.

Portola presented the data in a poster session titled "First in Human Experience with PRT060128, a New Direct-acting, Reversible P2Y(12) Inhibitor for IV and Oral Use" which describes the single ascending dose (SAD) study of the oral formulation of PRT060128. In this study, dose dependent and full inhibition of ADP-induced platelet aggregation was achieved. In addition, following administration of PRT060128, inhibition of platelet aggregation was fully reversed within 24 hours post dosing. All doses of PRT060128 were well tolerated. There were no serious adverse events and no discontinuations due to an adverse event.

"Successful results from both our Phase I oral and intravenous studies build a strong foundation for advancing PRT060128 in the clinic," said Dan Gretler, MD, Portola's vice president of Clinical Development and Regulatory Affairs. "We will initiate our Phase II clinical program later this year to further study the differentiated properties of our ADP receptor antagonist."

Portola's ADP Receptor Antagonist

PRT060128 is an antiplatelet drug that is the only intravenous (IV) and oral ADP receptor antagonist in clinical development. Portola believes that this compound may provide significant clinical benefit through immediate, high-level platelet inhibition in the acute setting and a seamless transition to predictable, reversible platelet inhibition in the chronic setting. Portola has studied this compound in a robust Phase I clinical development program including single ascending dose and multiple ascending dose studies with the oral
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