Inhibition of coagulation factor XI/XIa - the next step in increasing the safety of anticoagulant therapy?

Modern medicine places great emphasis not only on the efficacy but especially on the safety of the treatment. A common deficiency of anticoagulants inhibitingg the common pathway of the coagulation cascade (thrombin inhibitors, factor Xa inhibitors or antivitamins K) is an increased risk of clinically significant bleeding. A new strategy is being developed to inhibit the intrinsic pathway of the coagulation cascade, specifically to inhibit the synthesis or block the function of factor XI/XIa. This route is promising, as the most common indications of anticoagulants include activation of haemostasis by contact (induced e.g. by polyphosphates on the surface of activated platelets or by contact with a negative electrostatic surface) or by repair-inflammatory processes (especially by extracellularly released DNA fibres from neutrophilic leukocytes - NETs or by a number of cytokines). The condition for the activation of this intrinsic coagulation pathway is the stagnation of the blood, allowing the achievement of an effective local concentration of enzymes of the coagulation cascade. These conditions correspond to the two most common indications for anticoagulant therapy - prevention of thromboembolic events accompanying atrial fibrillation or prophylaxis and treatment of thromboembolic disease. Maintaining an active external coagulation pathway will then allow for the preservation of hemostasis in the event of damage to the vascular wall, e.g. damage to mucous membranes, injuries or surgeries. The types of drugs investigated in inhibition of factor XI/XIa demonstrate the current shift in pharmacological intervention options. In addition to classical small molecule drugs (e.g. asundexian, milvexian), monoclonal antibodies (e.g. abelacimab, osocimab) or oligonucleotide inhibitors (e.g. fesomersen) are being developed. A number of these drugs have completed the early phases of clinical trials, and in a number of indications (prophylaxis of thromboembolic disease after orthopaedic procedures, as part of the prevention of thromboembolic events in atrial fibrillation or in the indication of secondary prevention after myocardial infarction or stroke), the last preregistration phases of the trial are underway.

Keywords: intrinsic pathway of the coagulation cascade inhibiton, factor XI/XIa inhibitors, abelacimab, osocimab, asundexian, milvexian, fesomersen, anticoagulation.