Portola Pharmaceuticals, Inc. Announces Data Presentations From Thrombosis and Syk/JAK Franchises at American Society of Hematology Annual Meeting

SOUTH SAN FRANCISCO, CA--(Marketwire - December 06, 2012) - Portola Pharmaceuticals, Inc. today announced that data from five abstracts on multiple programs in the company's thrombosis and Spleen Tyrosine Kinase (Syk)/Janus Kinase (JAK) franchises will be presented at the American Society of Hematology (ASH) Annual Meeting, which is taking place at the Georgia World Congress Center in Atlanta from December 8-11.

Findings to be presented include:

• Data demonstrating limited drug-drug interactions with betrixaban, Portola's novel, oral Factor Xa inhibitor anticoagulant in Phase 3 development for the prevention of venous thromboembolism (VTE) in acute medically ill patients with certain risk factors
• Preclinical data on PRT4445, Portola's universal antidote for Factor Xa inhibitor anticoagulants
• Data from an evaluation of patients with bleeding symptoms using a novel perfusion chamber assay (PCA)
• Preclinical data on PRT2070, Portola's orally-available, potent inhibitor of Syk and the JAK family kinases that may have a role in inflammatory diseases and B-cell cancers
• Preclinical data on PRT0318, a highly specific, small molecular inhibitor of Syk, in acute lymphoblastic leukemia

Presentation details are as follows:

Thrombosis

Betrixaban

• Abstract title: "Metabolism and Disposition of Betrixaban and Its Lack of Interaction with Major CYP Enzymes" (Abstract #2266)
  Session: 332. Antithrombotic Therapy: Poster II
  Presentation date/time: Sunday, December 9, 6:00 p.m.-8:00 p.m. EST
  Presenter: Athiwat Hutchaleelaha, Ph.D., Portola Pharmaceuticals
  Location: Hall B1-B2, Level 1, Building B

PRT4445

• Abstract title: "PRT064445 but Not Recombinant FVIIa Reverses Rivaroxaban Induced Anticoagulation As Measured by Reduction in Blood Loss in a Rabbit Liver Laceration Model" (Abstract #3414)
• Session: 332. Antithrombotic Therapy: Poster III
  Presentation date/time: Monday, December 10, 6:00 p.m.-8:00 p.m. EST
  Presenter: Stanley J Hollenbach, Portola Pharmaceuticals
  Location: Hall B1-B2, Level 1, Building B

Bleeding Disorder Evaluation

• Abstract title: "Evaluation of Patients with Bleeding Symptoms Using a Novel Perfusion Chamber Assay (PCA)" (Abstract #3295)
  Session: 301. Platelet Activation and Biochemistry: Poster III
  Presentation date/time: Monday, December 10, 6:00 p.m.-8:00 p.m. EST
  Presenter: Gillian Stephens, Ph.D., Portola Pharmaceuticals
  Location: Hall B1-B2, Level 1, Building B

Syk/JAK

PRT2070

• Abstract title: "PRT062070: A Dual Syk/JAK Inhibitor with Potent Immune Regulatory Capacity in Rodent Models of Inflammation and Cancer" (Abstract #2764)
  Session: 625. Lymphoma - Pre-Clinical - Chemotherapy and Biologic Agents: Poster II
  Presentation date/time: Sunday, December 9, 6:00 p.m.-8:00 p.m. EST
  Presenter: Greg Coffey, Ph.D., Portola Pharmaceuticals
  Location: Hall B1-B2, Level 1, Building B

PRT060318

• Abstract title: "Efficacy of PRT060318, a Novel Highly Specific SYK Inhibitor, in Acute Lymphoblastic Leukemia (ALL)" (Abstract #3532)
  Session: 612. Acute Lymphoblastic Leukemia - Pathophysiology & Clinical Studies: Poster III
  Presentation date/time: Monday, December 10, 6:00 p.m.-8:00 p.m. EST
  Presenter: Stefan Köhrer, M.D., MD Anderson Cancer Center
  Location: Hall B1-B2, Level 1, Building B

About Portola Pharmaceuticals, Inc.
Portola Pharmaceuticals is a biopharmaceutical company focused on discovering, developing and commercializing novel therapeutics in the areas of thrombosis and hematologic disorders and inflammation. In thrombosis, Portola is developing betrixaban, a novel, oral, once-daily inhibitor of Factor Xa in development for extended duration venous thromboembolism (VTE) prophylaxis in acute medically ill patients (for up to 35 days). Portola also is developing PRT4445, a universal antidote for Factor Xa inhibitor anticoagulants. Portola has a short-term clinical collaboration agreement with Bristol-Myers Squibb and Pfizer for the initial Phase 2 clinical development of PRT4445, in which Portola retains 100 percent ownership.

Portola scientists have discovered novel dual inhibitors of Spleen Tyrosine Kinase (Syk) and Janus Kinase (JAK) for hematologic cancers and inflammation. Portola's lead compound in that program, PRT2070, has completed preclinical testing and, subject to regulatory approval, will enter the clinic in 2013. In inflammation, Portola has a collaboration agreement with Biogen Idec to develop specific inhibitors of Syk, including a formulation of PRT2607 for which Biogen Idec is leading development for the treatment of allergic asthma. The collaboration is also focusing on additional selective backup compounds for oral administration in chronic autoimmune and inflammatory diseases. For more information, visit www.portola.com.