Development of an innovative approach based on targeted anticoagulation for the treatment of VTE

Introduction: Venous thromboembolism (VTE) is the third leading cause of death worldwide. It is a common thrombotic disorder encompassing deep vein thrombosis and pulmonary embolism. Anticoagulant drugs reduce the burden of VTE, but foster an increased risk of bleeding [2] [3]. Moreover, despite the existing VTE treatments, there is still an important fatality case [4] [5] and chronic VTE sequels are frequent [6]. Therefore, we developed an innovative anticoagulation approach, based on an antibody-drug-conjugate (ADC) combining a highly specific anti-fibrin antibody to the direct thrombin inhibitor, hirudin. As this agent concentrates within a fibrin-rich thrombus, a very low systemic concentration is required to achieve efficient anticoagulation at site of thrombosis. This also implies a low bleeding risk [1].

Method: We generated four ADCs molecules. Their anticoagulant potential and enzymatic activity were tested using aPTT and a fluorogenic assay. The ability of one of the molecules to bind fibrin was studied in a microfluidic model based on fibrin formation in the chamber. Its pharmacokinetic was studied in mice using aPTT. The antithrombotic effect of one ADC was compared to hirudin in experimental models of arterial thrombosis, thromboembolism (TE) via tissue factor (TF) injection and venous thrombosis (VT) via siRNA injection. Finally, the impact on hemostasis was determined in a tail-bleeding assay.

Results: Amongst the four ADCs, we selected ADC-Hir10 based on its efficient anticoagulant effect in the aPTT assay. Its anticoagulant potential reached 65% compared to hirudin. Its ability to bind immobilized fibrin was evidenced in a microfluidic assay. Concerning its pharmacokinetic, a dose of 0.1 mg/kg of ADC-hir10 injected IV, entailed an anticoagulant effect for up to 30 hours, while 10 mg/kg of hirudin was active for less than 6 hours ([Fig 1A]). The ADC-hir10 showed superiority over an equivalent dose of hirudin in the FeCl₃-injury model on the carotid artery, in the TF-induced TE ([Fig 1B-C]) and in the siRNA-induced VT model. Finally, the ADC-Hir10 did not prolong the tail-bleeding time at the low doses it provided protection in the TE and VT models.

Fig. 1 Pharmacokinetics of ADC-Hir10 and its efficacy in two experimental models of thrombosis. A . Pharmacokinetics of ADC-Hir10. Blood was collected post IV injection of Control antibody (Ctrl), ADC-hir10 or hirudin (hir). The anticoagulant effect was determined using an aPTT test. B. Thrombus formation in mice treated with Ctrl, ADC-Hir10, or hir in a FeCl ₃ injury of a mouse carotid. C. Platelet consumption in mice treated with Ctrl, ADC-Hir10 or hir at equivalent doses in a tissue factor (TF)-induced thromboembolism model. Note: all doses here are hirudin doses and were injected in thrombosis models at a similar anticoagulant effect of hirudin, determined in vitro.

Conclusion: We developed a promising targeted strategy that efficiently prevents experimental thrombosis with no impact on hemostasis.

Publication History

Article published online:
13 February 2025

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