Pfizer, Bristol team up with Portola for study of Eliquis antidote

Developers of new blood thinners want to address a major safety issue. Portola Pharmaceuticals has found support from drug giants Pfizer ($PFE) and Bristol-Myers Squibb ($BMY) for a proof-of-concept study of Portola's therapy for stymieing serious bleeding that occurs in a small percentage of patients who take blood thinners.

South San Francisco-based Portola, a 2009 Fierce 15 company, expects to start the study by the end of this year. The company's protein drug, PRT4445, is supposed to reverse the activity of oral Factor Xa inhibitors such as Pfizer and Bristol's blockbuster hopeful Eliquis, or apixaban. The study will investigate the use of PRT4445 to serve as an antidote to Eliquis as well as similar drugs such as Portola's betrixaban. Portola is keeping all development and commercial rights to PRT4445 in the deal.

"Patient safety and improved patient outcomes have guided our clinical development program for Eliquis, including our efforts to identify a reversal agent for urgent clinical situations," Brian Daniels, BMS' senior vice president, global development and medical affairs, said in statement. "With our partner Pfizer, we look forward to working with Portola to advance the scientific understanding of the role of PRT4445 as a potential antidote for Eliquis."

Bleeding risks have raised red flags with regulators as they scrutinize Eliquis and other next-generation blood thinners angling for their share of a multibillion-dollar market. According to Portola, there are no approved drugs for arresting anticoagulants in the class of drugs that includes Pfizer/BMS' and its own experimental compound. The agreement for the proof-of-concept study for PRT4445 comes as the FDA reviews Eliquis for patients with atrial fibrillation.

The agency is scheduled to take action on the application in application by March 17, 2013, with its decision expected to have a major impact on the market reach of the therapy. U.S. regulators have raised concerns about the risks associated with new blood thinners, including Eliquis and the rival therapy Xarelto from Bayer and Johnson & Johnson ($JNJ).

- here's the release

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