Evaluation of potential antigenicity of active-site-inhibited recombinant human FVIIa (FFR-rFVIIa) in an immune-tolerant rat model

• Published in: Thrombosis and haemostasis Vol. 87; no. 5; p. 836
• Main Authors: Nicolaisen, Else Marie, Kristensen, Hanne, Kristensen, Annemarie, Hedner, Ulla
• Format: Journal Article
• Language: English
• Published: Germany 01.05.2002
• Subjects: Amino Acid Chloromethyl Ketones - pharmacology; Animals; Animals, Newborn; Antibodies, Heterophile - biosynthesis; Antibodies, Heterophile - immunology; Antigens, Heterophile - chemistry; Antigens, Heterophile - genetics; Antigens, Heterophile - immunology; Binding Sites - drug effects; Enzyme Inhibitors - pharmacology; Enzyme-Linked Immunosorbent Assay; Factor VIIa - administration & dosage; Factor VIIa - antagonists & inhibitors; Factor VIIa - chemistry; Factor VIIa - genetics; Factor VIIa - immunology; Female; Humans; Immune Tolerance; Immunization; Immunization, Secondary; Injections, Intraperitoneal; Injections, Intravenous; Male; Models, Animal; Rats; Rats, Wistar; Recombinant Fusion Proteins - administration & dosage; Recombinant Fusion Proteins - antagonists & inhibitors; Recombinant Fusion Proteins - chemistry; Recombinant Fusion Proteins - immunology; Species Specificity; Specific Pathogen-Free Organisms
• ISSN: 0340-6245
• DOI: 10.1055/s-0037-1613093

Recombinant human FVIIa (rFVIIa) was inactivated by coupling Phe-Phe-Arg-CK- (FFR) covalently to the active site of the enzyme. To test the chemically-modified human protein for potential antigenicity prior to clinical trial an immune-tolerant rat model was established. Intraperitoneal injection of the parent compound, human rFVIIa, within 30 h after birth, followed by repeated subcutaneous challenge with rFVIIa in Freunds incomplete adjuvant resulted in 79% non-responding rats at day 32. Monthly subcutaneous challenge showed that the induced tolerance was stable over the 3 months study period in 80% of the rats. The clinically relevant route, intravenous administration, was used for evaluating the potential antigenicity of FFR-rFVIIa. Repeated intravenous administration of different dosages of FFR-rFVIIa did not break tolerance, indicating that FFR-rFVIIa might not be antigenic, for a limited number of intravenous administrations in a clinical setting.