Discovery of the Low-Hemorrhagic Antithrombotic Effect of Montelukast by Targeting FXIa in Mice

BACKGROUND: FXIa (coagulation factor XIa) is considered as a promising antithrombotic target with reduced hemorrhagic liabilities. The objective of this study was to identify a small-molecule inhibitor of FXIa as a potential low-hemorrhagic anticoagulant. METHODS: A high-throughput virtual screening was conducted using a drug repurposing library with the catalytic domain of FXIa as the bait. The identified inhibitor’s anticoagulant activity was evaluated in vitro and in both arterial and venous murine thrombotic models. The dependency of the inhibitor on FXIa was further examined using FXI −/− mice. Hemorrhagic risks were subsequently evaluated in models of both localized and major bleeding. RESULTS: Virtual screening led to the identification of montelukast, a commonly used antiasthmatic drug, as a potent and specific FXIa inhibitor (half maximal inhibitory concentration of 0.17 μmol/L). MK exhibited anticoagulant effects comparable to those of 2 mostly prescribed anticoagulants (warfarin and apixaban) in both arterial and venous thrombotic models. Notably, in stark contrast to the pronounced hemorrhagic risks of warfarin and apixaban, MK did not measurably increase the tendency of localized or major bleeding. Furthermore, MK did not prolong the time to arterial thrombotic occlusion in FXI −/− mice, while effectively inhibited arterial occlusion induced by the reinfusion of recombinant FXIa, confirming that MK’s anticoagulant activity is mediated by plasma FXIa. Additionally, MK ameliorated inflammation levels and mitigated pulmonary microthrombus formation in a septic mouse model. Moreover, combination therapy with MK enhanced the antithrombotic effects of antiplatelets without an obvious increase of hemorrhage. CONCLUSIONS: This proof-of-concept study suggests the potent low-hemorrhage antithrombotic effect of MK by targeting FXIa and unveiling a new therapeutic application of MK.