Coagulation factor VIII (FVIII) (FVIII)

Coagulation factor VIII (FVIII) is a large, multi-domain glycoprotein that serves as an essential cofactor in the intrinsic pathway of the blood coagulation cascade [2, 13]. It circulates in the plasma as an inactive procofactor, primarily stabilized by its non-covalent association with von Willebrand factor (VWF) [3, 14]. Upon activation by thrombin or factor Xa, FVIIIa dissociates from VWF and assembles with activated factor IX (FIXa) on phospholipid surfaces to form the "tenase" complex [1, 20]. This complex dramatically accelerates the activation of factor X to factor Xa, which is a critical step for the subsequent generation of thrombin and the formation of a stable fibrin clot [3, 13]. Deficiency or functional defects in FVIII result in Hemophilia A, a hereditary X-linked bleeding disorder characterized by spontaneous or excessive bleeding into joints, muscles, and soft tissues [2, 12]. Therapeutic strategies focus on physiological replacement using recombinant or plasma-derived FVIII concentrates to restore hemostatic function [13, 18]. However, the development of neutralizing antibodies, known as inhibitors, remains a major clinical challenge that can render replacement therapy ineffective [6, 16]. Newer treatment modalities include gene therapy to provide endogenous production and bispecific antibodies that mimic FVIII function [7, 23].

Other names

Antihemophilic factorAntihemophilic factor AAntihemophilic globulinFactor VIIIcF8F8CHEMA

Acts as a cofactor for activated factor IX (FIXa) in the intrinsic tenase complex, which converts factor X to activated factor Xa on phospholipid surfaces in the presence of calcium ions.