US-based Portola Pharmaceuticals has entered into a second clinical collaboration agreement with Daiichi Sankyo to evaluate andexanet alfa, Portola's investigational Factor Xa inhibitor antidote, in Phase III registration trials with Daiichi Sankyo's Factor Xa inhibitor edoxaban.
Both firms originally entered into a collaboration agreement in June 2013, which covered a Phase II proof-of-concept trial, which results are anticipated for later in 2014.
The Phase III edoxaban trials, also known as ANNEXA- E ('Andexanet Alfa a Novel Antidote to the Anticoagulant Effects of fXA Inhibitors - Edoxaban'), are scheduled to begin in 2015.
As part of the non-exclusive collaboration deal, Portola will get an upfront payment and is also eligible to receive additional development and regulatory milestone payments.
Portola Pharmaceuticals retains full, worldwide commercial rights to andexanet alfa, for which the company is pursuing an Accelerated Approval pathway.
Portola Pharmaceuticals chief executive officer William Lis said: "This, combined with the FDA's designation of andexanet alfa as a breakthrough therapy, underscores the significant need for an antidote for the millions of patients currently being treated with these novel anticoagulants.
"We are pursuing an accelerated approval pathway for andexanet alfa in order to bring this novel therapy to market as quickly as possible for the benefit of patients."
The FDA breakthrough therapy designated 'andexanet alfa' is a first-in-class recombinant, modified Factor Xa molecule and is being developed as a direct reversal agent for patients receiving a Factor Xa inhibitor who suffer a major bleeding episode or who may require emergency surgery.
The drug acts as a Factor Xa decoy that targets and sequesters with high specificity both direct and indirect Factor Xa inhibitors in the blood.
Portola is currently assessing andexanet alfa in Phase III trials with Bristol-Myers Squibb (BMS) and Pfizer's Eliquis (apixaban), and Bayer HealthCare and Janssen's Xarelto (rivaroxaban).
These randomised, double-blind, placebo-controlled trials are designed to assess the safety and efficacy of andexanet alfa in reversing Eliquis or XARELTO-induced anticoagulation rapidly after an IV bolus and sustaining that effect through a continuous infusion.
The company said that a Phase II proof-of-concept trial with Daiichi Sankyo's Factor Xa inhibitor edoxaban is ongoing, and a Phase II proof-of-concept study with Portola's Factor Xa inhibitor betrixaban is planned.