Factor XI and contact activation as targets for antithrombotic therapy

Area of Science:

• Hematology
• Vascular Biology
• Drug Discovery

Background:

• Current anticoagulants inhibit thrombin or factor Xa (FXa), increasing bleeding risk by impairing hemostasis.
• The plasma contact activation system, involving factor XI (FXI) and factor XII (FXII), contributes to thrombosis but not hemostasis.

Purpose of the Study:

• To review the role of FXI and FXII in thrombosis.
• To evaluate preclinical and human trial data for therapies targeting FXI and FXII.

Main Methods:

• Review of existing literature on contact activation system components (FXI, FXII) in thrombosis.
• Analysis of preclinical studies and human clinical trials for FXI- and FXII-targeted therapies.

Main Results:

• Epidemiologic data link FXI to stroke, venous thromboembolism, and myocardial infarction.
• A Phase 2 trial indicated FXI reduction may be superior to low molecular weight heparin in preventing venous thrombosis post-knee surgery.

Conclusions:

• Targeting FXI and FXII offers a promising strategy to decouple antithrombotic effects from anticoagulant activity.
• Therapies targeting contact activation components may provide safer antithrombotic options for high-risk patients.