The use of antibodies to coagulation factors for anticoagulant therapy

Current treatments for preventing thrombotic diseases are associated with a significant risk of bleeding. Improved anticoagulant agents are therefore still required. The specificity and pharmacokinetics properties of monoclonal antibodies to coagulation factors allow novel anticoagulation approaches. Treatment with human antibodies or humanized mouse monoclonal antibodies should avoid unacceptable side effects due to immune response to the drug. Such antibodies were developed against three coagulation factor: Tissue factor (TF), Factor IX (FIX) and Factor VIII (FVIII). A fully humanized antibody was successfully derived from a mouse monoclonal antibodies to TF. In vivo studies with monoclonal antibodies to TF demonstrated efficient antithrombotic activity. Anti-TF antibodies may also prove useful in cardiovascular disorders and cancer, given the role of TF in these diseases. Mouse and human monoclonal antibodies to FIX were also efficient to prevent thrombosis in animal models of venous and arterial thrombosis and in stroke. A humanized anti-FIX antibody was tested in phase I study in healthy volunteers. The pharmacokinetics of the antibody were determined by the rapid formation of stable complexes with newly synthesised FIX. Human anti-FVIII antibodies inhibiting only partially FVIII activity were recently described. Investigations in mice have established that treatment with such anti-FVIII antibodies is efficient to prevent deep vein thrombosis. Given the low concentration of FVIII in plasma and the long half-life of antibody, treatment with anti-FVIII antibody could be very convenient, allowing one administration every month. Altogether, monoclonal antibodies to coagulation factor appear as promising novel antithrombotic drugs.