K-IX-2

K-IX-2 is a novel, canine-specific homodimeric antibody designed as a hemostatic treatment for severe hemophilia A, particularly in dogs with canine factor VIII (FVIII) inhibitors. It was developed by grafting the complementarity-determining region (CDR) of the factor IXa (FIXa) binding arm of denecimig (Mim8) onto the two arms of canine IgG4. K-IX-2 promotes canine FIXa activation of canine factor X (FX), enhances factor XIa (FXIa)-initiated thrombin generation, shortens whole blood clotting time (WBCT), and improves thromboelastography (TEG) parameters. In preclinical studies of severe hemophilia A dogs with FVIII inhibitors, K-IX-2 significantly reduced both the annualized bleeding rate (ABR) and annualized infusion rates (AIR) and was clinically well-tolerated.