Portola Pharmaceuticals Announces Enrollment Has Begun In Phase 1/2 Study Of PRT2070, An Oral Dual Syk/JAK Inhibitor For Genetically-Defined Hematologic Cancers

SOUTH SAN FRANCISCO, Calif., Oct. 24, 2013 (GLOBE NEWSWIRE) -- Portola Pharmaceuticals (Nasdaq:PTLA) today announced that patient enrollment has begun in its PRT2070 Phase 1/2 proof-of-concept clinical study. PRT2070 is a novel, oral, dual spleen tyrosine kinase (Syk) and janus kinase (JAK) inhibitor being developed as a treatment for hematologic cancers, including for those patients who have progressive or relapsed disease, genetically-defined subtypes or acquired mutations.

"It is clear that new treatment options are needed for patients with relapsed and refractory lymphoma, chronic lymphocytic leukemia and other lymphoproliferative disorders," said Ian W. Flinn, M.D., Ph.D., director, Hematologic Malignancies Research Program at Sarah Cannon Research Institute (SCRI) and investigator for the PRT2070 Phase 1/2 study. "We are excited to see enrollment has begun for this novel agent, which targets important pathways in these diseases."

PRT2070 is an oral, potent inhibitor of both the B-cell receptor (BCR) pathway via Syk and key JAK-mediated cytokines. These two pathways promote survival and proliferation of hematologic cancers, such as non-Hodgkin's lymphoma (NHL) and chronic lymphocytic leukemia (CLL). PRT2070, with its dual mechanism of action that targets two pathways for acquired and pre-existing mutations or resistance, is unique in that it simultaneously targets these two validated pathways in a single pill. This may distinguish it in difficult-to-treat leukemia and lymphoma patient populations with certain genetic subtypes, such as diffuse large B-cell lymphoma (DLBCL), as well as in patients with acquired mutations who may have relapsed on existing treatments.

An estimated 560,000 people in the United States are living with NHL and approximately 120,000 people are estimated to be living with CLL. i

About the PRT2070 Phase 1/2 Study

The open-label, multicenter, Phase 1/2 proof-of-concept study is assessing the safety, pharmacokinetics, pharmacodynamics and clinical activity of oral PRT2070. In the multi-dose, dose-escalation Phase 1 part of the study, PRT2070 is being administered to sequential dose cohorts at increasing dose levels until the maximum tolerated dose is identified. This portion of the study can include patients with relapsed or refractory CLL/small lymphocytic lymphoma and NHL (including DLBCL, follicular lymphoma and mantle cell lymphoma). The Phase 2 part of the study is a cohort expansion that will evaluate measures of safety and efficacy in cancer types identified based on the responses seen in the dose-escalation phase. SCRI, a global strategic research organization based in Nashville, Tenn., has been engaged by Portola to conduct the study.

About Portola Pharmaceuticals, Inc.

Portola Pharmaceuticals is a biopharmaceutical company focused on the development and commercialization of novel therapeutics in the areas of thrombosis, other hematologic disorders and inflammation. Portola's wholly-owned lead compound, betrixaban, is a novel, oral, once-daily Factor Xa inhibitor in Phase 3 development for extended-duration prophylaxis of a form of thrombosis known as venous thromboembolism (VTE) in acute medically ill patients. Currently, there is no anticoagulant approved for extended-duration VTE prophylaxis in this population. Portola's second lead development candidate, andexanet alfa (PRT4445*), has the potential to be the first universal antidote to reverse the effects of Factor Xa inhibitors in patients who suffer an uncontrolled bleeding episode or who require emergency surgery. Portola retains full, worldwide commercial rights to andexanet alfa. Portola's third product candidate, PRT2070, is an orally available kinase inhibitor that uniquely inhibits two validated tumor proliferation pathways -- spleen tyrosine kinase (Syk) and janus kinase (JAK). It is currently being studied in patients with genetically-defined hematologic cancers, as well as for patients who have failed therapy due to relapse or acquired mutations. Portola's fourth program is partnered with Biogen Idec and is focused on the development of PRT2607, a selective Syk inhibitor. For more information, visit www.portola.com.

Forward-looking statement

Statements contained in this press release regarding matters that are not historical facts are "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995. Because such statements are subject to risks and uncertainties, actual results may differ materially from those expressed or implied by such forward-looking statements. Such statements include, but are not limited to, statements regarding the use of PRT2070 as a kinase inhibitor and Portola's Phase1/2 proof-of-concept study for PRT2070. Risks that contribute to the uncertain nature of the forward-looking statements include: the accuracy of Portola's estimates regarding its ability to initiate and/or complete its clinical trials; the success of Portola's clinical trials and the demonstrated efficacy of Portola's product candidates thereunder; the accuracy of Portola's estimates regarding its expenses and capital requirements; regulatory developments in the United States and foreign countries; Portola's ability to obtain and maintain intellectual property protection for its product candidates; and the loss of key scientific or management personnel. These and other risks and uncertainties are described more fully in Portola's most recent filings with the Securities and Exchange Commission. All forward-looking statements contained in this press release speak only as of the date on which they were made. Portola undertakes no obligation to update such statements to reflect events that occur or circumstances that exist after the date on which they were made.

*PRT4445 has a proposed International Nonproprietary Name (pINN) of andexanet alfa.

i http://www.lls.org/#/diseaseinformation/lymphoma/nonhodgkinlymphoma/incidence. Accessed 10/24/13.

http://www.lls.org/#/diseaseinformation/leukemia/chroniclymphocyticleukemia/incidence. Accessed 10/24/13.
CONTACT: Investor Contact:         Alexandra Santos         Portola Pharmaceuticals         ir@portola.com         650.246.7239                  Media Contact:         Joey Fleury         BrewLife         jfleury@brewlife.com         415.946.1090

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