Tissue factor pathway inhibitor (TFPI) (TFPI)

Tissue factor pathway inhibitor (TFPI) is a Kunitz-type serine protease inhibitor that serves as the primary physiological regulator of the initiation of blood coagulation. It is synthesized and predominantly stored in vascular endothelial cells, where it exists in both a membrane-bound form (via GPI-anchors) and within intracellular granules (UniProt: P10646). TFPI functions by first binding and inhibiting Factor Xa, and subsequently inhibiting the Factor VIIa-tissue factor complex in a quaternary structure, effectively halting the extrinsic pathway of thrombin generation (PubMed: 25659438). In modern pharmacology, TFPI has emerged as a significant therapeutic target for hemophilia A and B; monoclonal antibodies such as concizumab and marstacimab inhibit TFPI to bypass the need for Factor VIII or IX and restore hemostasis (PubMed: 30154113). Additionally, the pharmacological release of TFPI from endothelial stores into the plasma is a recognized mechanism contributing to the systemic anticoagulant efficacy of unfractionated and low-molecular-weight heparins (PubMed: 15141311). Therapeutic modulation of TFPI requires careful balance, as excessive inhibition can lead to thrombosis, while insufficient activity contributes to bleeding diatheses.

Other names

Extrinsic pathway inhibitorEPILipoprotein-associated coagulation inhibitorLACITFPI1Tissue factor pathway inhibitor 1

Inhibition of TFPI to enhance thrombin generation in hemophilia; stimulation of TFPI release from endothelial cells to provide anticoagulation.