In vivo clearance and metabolism of recombinant activated factor VII (rFVIIa) and its complexes with plasma protease inhibitors in the liver.
BACKGROUND
Recombinant activated factor VII (rFVIIa, NovoSeven®) is injected intravenously for the treatment of haemophilia patients with inhibitory antibodies. In plasma, rFVIIa forms complexes with protease inhibitors, primarily antithrombin III (ATIII). The liver is believed to be involved in clearance of rFVIIa, however, it is not known whether the liver is also involved for the clearance of the rFVIIa-ATIII complex. In this study, we explored the fate of intravenously injected rFVIIa from plasma to the hepatic lysosomes.


METHODS
A novel method using magnetic chromatography was used to isolate catabolic organelle (CO) fractions from mouse liver following injection of superparamagnetic dextran (SPD)-coated iron oxide particles and rFVIIa. The effect of co-circulating SPD particles on rFVIIa pharmacokinetic (PK) parameters was evaluated by ELISA. Cryo-immuno transmission electron microscopy (TEM) was used to study hepatic distribution of SPD particles and rFVIIa. The isolated hepatic CO fractions were characterized using Western Blotting (WB).


RESULTS
Cryo-immuno TEM of the liver confirmed hepatic co-localisation of SPD particles and rFVIIa in identical endosomes and lysosomes of both hepatocytes and Kupffer cells. SPD particles did not affect the PK parameters of rFVIIa. WB analysis of plasma and CO fractions detected rFVIIa as the full-length protein and also in high molecular weight (HMW) complexes with ATIII and α-2 macroglobulin (α-2M).


CONCLUSIONS
Following injection, both hepatocytes and Kupffer cells appeared to be involved in the hepatic clearance and metabolism of both full-length rFVIIa and rFVIIa in complex with at least two plasma protease inhibitors; ATIII and α-2M.
Department of Pharmaceutics and Analytical Chemistry, Faculty of Pharmaceutical Sciences, University of Copenhagen, Copenhagen, Denmark. tojo@novonordisk.com
T
T
Seested
R S
RS
Appa
E I
EI
Christensen
Y A
YA
Ioannou
T N
TN
Krogh
D M
DM
Karpf
H M
HM
Nielsen
D000818:Animals; D002845:Chromatography / Q000379:methods; D003911:Dextrans / Q000737:chemistry; D015942:Factor VIIa / Q000008:administration & dosage / Q000378:metabolism* / Q000493:pharmacokinetics; D005290:Ferric Compounds / Q000737:chemistry; D022781:Hepatocytes / Q000378:metabolism; D007275:Injections, Intravenous; D008099:Liver / Q000378:metabolism*; D008280:Magnetics; D008297:Male; D051379:Mice; D011480:Protease Inhibitors / Q000378:metabolism*; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000378:metabolism / Q000493:pharmacokinetics
D003911:Dextrans; D005290:Ferric Compounds; D011480:Protease Inhibitors; D011994:Recombinant Proteins; C000499:ferric oxide; C103587:recombinant FVIIa; D015942:Factor VIIa