Predicting the metabolic characteristics of neorudin, a novel anticoagulant fusion protein, in patients with deep vein thrombosis

Introduction: Recombinant neorudin (EPR-hirudin, EH) is an inactive prodrug that is converted to its active metabolite, hirudin variant 2-Lys47 (HV2), at the thrombus site. We aimed to investigate the mechanism underlying site-selective bioconversion of EH to HV2 at the thrombus target site and metabolic transformation of EH in patients with deep vein thrombosis (DVT). Materials and methods: Metabolites in healthy volunteer plasma and urine after intravenous administration of EH were determined to elucidate how EH was metabolised after releasing HV2 at the target site in patients with DVT. After intravenous administration of EH in rats with venous thrombosis, the concentrations of EH in the blood and thrombus and the antithrombotic activity of EH were measured to predict whether EH could release HV2 at the thrombus site to exert anticoagulant effect in patients with DVT. Results: In healthy volunteers, EH and HV2 were predominantly excreted in the urine. Nine EH metabolites and ten HV2 metabolites truncated at the C-terminal were identified as N-terminal fragments, and these had the same cleavage sites. In rats with venous thrombosis, the area under the curve ratio of HV2 between the thrombus and blood was 29.5. The weight of wet thrombus was decreased with the production of HV2 by the cleavage of EH. The prothrombin time (PT) and prothrombin time (TT) changed proportionally to the concentration of EH and HV2 in the blood. Conclusion: EH selectively accumulates and releases HV2 in the thrombus to exert antithrombotic effects, thus lowering the bleeding risk. Moreover, after conversion, EH may follow the same metabolic profile as that of HV2 in patients with DVT.