Xa and IX mark the clot

Two research teams have separately reported engineered variants of clotting factors Xa and IX that could become next-generation hemophilia therapies.^1,2 Pfizer Inc. has exclusively licensed the factor Xa variant, while an undisclosed company has licensed the modified factor IX.

In one of the studies, researchers at The Children's Hospital of Philadelphia and Pfizer showed that a mutant variant of human factor Xa stopped acute bleeding in mouse models of hemophilia. In the second study, a group led by researchers at the German Red Cross Blood Donor Service Baden-Wuerttemberg-Hessen designed a recombinant human factor IX variant that decreased bleeding times in mice...