American Society of Hirudotherapy

Plasma contact factors as therapeutic targets.

Review published in Blood reviews (2018)

Last Updated: June 18, 2026Reviewed by: ASH Editorial Board
Research article — evidence reviewArticle reference
Evidence: Narrative reviewDrug DevelopmentSalivary PharmacologyTillman et al. · Blood reviews, 2018

Abstract

Direct oral anticoagulants (DOACs) are small molecule inhibitors of the coagulation proteases thrombin and factor Xa that demonstrate comparable efficacy to warfarin for several common indications, while causing less serious bleeding. However, because their targets are required for the normal host-response to bleeding (hemostasis), DOACs are associated with therapy-induced bleeding that limits their use in certain patient populations and clinical situations. The plasma contact factors (factor XII, factor XI, and prekallikrein) initiate blood coagulation in the activated partial thromboplastin time assay. While serving limited roles in hemostasis, pre-clinical and epidemiologic data indicate that these proteins contribute to pathologic coagulation. It is anticipated that drugs targeting the contact factors will reduce risk of thrombosis with minimal impact on hemostasis. Here, we discuss the biochemistry of contact activation, the contributions of contact factors in thrombosis, and novel antithrombotic agents targeting contact factors that are undergoing pre-clinical and early clinical testing.

Abstract sourced from PubMed (NCBI) for the cited record. See the original publication for the authoritative version.

Publication typeJournal ArticleResearch Support, N.I.H., ExtramuralReview
Indexed MeSH termsAnimalsBlood CoagulationBlood Coagulation FactorsCoagulation Protein DisordersCombined Modality TherapyDrug Evaluation, PreclinicalHemostasisHumansMolecular Targeted TherapyProtein BindingThrombin

Summary

Direct oral anticoagulants (DOACs) are small molecule inhibitors of the coagulation proteases thrombin and factor Xa that demonstrate comparable efficacy to warfarin for several common indications, while causing less serious bleeding. However, because their targets are required for the normal host-response to bleeding (hemostasis), DOACs are associated with therapy-induced bleeding that limits their use in certain patient populations and clinical situations.

Why This Matters for Hirudotherapy

Informs the development and characterization of anticoagulant and leech-derived therapeutic agents.

Citation

Plasma contact factors as therapeutic targets.

Tillman et al. · Blood reviews, 2018

Added to ASH library: May 28, 2026 · Site last updated: June 18, 2026

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