Soy Phosphatidylinositol-Containing Lipid Nanoparticle Prolongs the Plasma Survival and Hemostatic Efficacy of B-domain-Deleted Recombinant Canine Factor VIII in Hemophilia A Dogs.

Soy phosphatidylinositol (PI)-containing lipid nanoparticles prolong plasma survival, improve hemostatic efficacy, and decrease immunogenicity of human B-domain-deleted factor VIII (BDD FVIII) in hemophilia A (HA) mice. We hypothesize that PI-associated BDD FVIII is more potent than the free protein and, using mathematical modeling, have projected that PI-associated BDD FVIII could be used for once-weekly prophylactic dosing in patients. To facilitate translation to the clinic, comparative plasma survival and ex vivo efficacy of PI-associated recombinant canine FVIII (PI-rcFVIII) were evaluated in HA dogs. Two HA dogs were administered a 50-U/kg intravenous dose of free or PI-rcFVIII. rcFVIII activity measurements and ex vivo efficacy analyses such as whole blood clotting time and thromboelastography were conducted on recovered plasma and whole blood samples. PI association decreased clearance (∼25%) and increased plasma exposure (∼1.4-fold) of rcFVIII. PI-rcFVIII-treated animals had prolonged improvements in whole blood clotting time and thromboelastography parameters compared to free rcFVIII-treated animals. Because rcFVIII is a BDD form of FVIII, these studies provide proof of principle that observations with human BDD FVIII in mice translate to higher animal species. In addition, PI-rcFVIII has potential applications in canine HA management and as a bypass therapy in inhibitor-positive HA patients.