BMS-654457 is a small-molecule, reversible inhibitor of factor XIa (FXIa), binding with human and rabbit FXIa with K_is of 0.2 and 0.42 nM, respectively. In Vitro: BMS-654457 shows comparable in vitro potency against FXIa in humans (Ki=0.2 nM) and in rabbits (Ki =0.42 nM), and was over 500-fold selective against coagulation-related proteases (thrombin, FXa and FVIIa) in these species^[1]. In Vivo: BMS-654457 is effective in the prevention of arterial thrombosis in rabbits with limited effects on bleeding time. BMS-654457 is a promising antithrombotic therapy with a wide therapeutic window^[1].