US-based biopharmaceutical firm Portola Pharmaceuticals has received breakthrough therapy designation from the US Food and Drug Administration (FDA) for its investigational Factor Xa inhibitor antidote, ‘andexanet alfa’.
The company is pursuing an Accelerated Approval pathway for andexanet alfa, a first-in-class agent, and plans to start registration-enabling studies in 2014.
Portola chief executive officer William Lis said: "The FDA’s decision to designate andexanet alfa as a breakthrough therapy reaffirms the urgent need for an antidote to Factor Xa inhibitors, and we believe it demonstrates that andexanet alfa’s properties and data distinguish it from currently used agents or others in development.
"Pro-coagulant agents being used in the absence of an antidote are unproven, have limited biological rationale for their effectiveness to reverse Factor Xa inhibitors, and have been shown to cause serious blood clots.
"Therefore, andexanet alfa marks an important advance in the field, and our goal is to bring it to market as quickly as possible."
According to the company, Phase II results to date have shown andexanet alfa’s ability to immediately reverse the anticoagulant activity of Factor Xa inhibitors by the administration of a short intravenous bolus.
Additional data has demonstrated that the reversal can be prolonged when necessary by the addition of an extended infusion of andexanet alfa.
The company said that no serious adverse events or antibodies to Factor Xa or Factor X have been observed in the ongoing Phase II trials.
The company has already reported data from its ongoing Phase II proof-of-concept studies of andexanet alfa and the Factor Xa inhibitors Eliquis and Xarelto.
Additional studies are currently ongoing with Lovenox (enoxaparin), Lixiana and the company’s investigational oral Factor Xa inhibitor, betrixaban.
Betrixaban is currently being studied in a Phase III clinical trial, and is claimed to have the potential to be the first oral Factor Xa inhibitor approved for venous thromboembolism (VTE) prevention in acute medically ill patients.
According to company estimates, the number of patients presenting to the hospital who could benefit from an antidote could approach 500,000 in the US, Japan and the five largest EU countries alone by 2020.