Distribution of Alprolix in the Blood Vessel Wall

By Dr. David Clark 

12/8/24 

We know that factor IX binds to collagen-IV inside the walls of blood vessels and that this bound factor IX is important for good clotting.  We don’t know a lot more about that, but this is an active area of research.  One thing that is not clear is whether the modifications made to factor IX to create extended half-life products affects the binding and distribution.  Studies by Sanofi a few years ago [van der Flier A et al., Blood Coagul Fibrinolysis, 34, 353-363, 2023] showed that Alprolix does distribute to other tissues outside the bloodstream.  A group of Canadian researchers has now looked at this in more detail. 

Hemophilic mice were given Alprolix, then tissue samples were taken after 48 hours and examined.  After 48 hours, the concentration of Alprolix in the blood was <1% (severe hemophilia) but the mice still had better bleeding scores than the control mice (also <1%) who had been given only saline.   

Alprolix was still found in a number of tissue samples.