A Novel KGD-Based αIIbβ3 Antagonist Prevents Arterial Thrombosis While Preserving Hemostasis and Avoiding Thrombocytopenia.

Current αIIbβ3 antagonists are potent antithrombotic agents, their clinical use is limited by the risk of life-threatening bleeding. Emerging evidence has highlighted key mechanistic differences between thrombosis and hemostasis, opening avenues for safer antithrombotic strategies. Targeting integrin αIIbβ3 outside-in signaling has been proposed to mitigate bleeding risk; however, the short half-life of peptide-based therapeutics remains a major challenge. In this study, we developed an optimized αIIbβ3 antagonist, KGDRR-a recombinant mutant protein derived from snake venom disintegrin, incorporating an Arg55 residue within the KGD loop-through systematic structure-activity relationship (SAR) analysis. Molecular docking revealed a critical cation-π interaction between Arg55 of KGDRR and Tyr122 of the β3 subunit, stabilizing integrin αIIbβ3 in an unliganded-closed conformation. Functionally, KGDRR selectively inhibited thrombus propagation by blocking ligand binding and downstream Gα13-mediated outside-in signaling while preserving initial thrombus core formation, which is a limitation of current αIIbβ3 inhibitors. Unlike conventional antagonists, KGDRR maintained αIIbβ3 in an unliganded-closed conformation without inducing the integrin activation and conformational change that lead to immune-mediated platelet clearance and thrombocytopenia. In animal models, KGDRR effectively suppressed thrombus growth without causing thrombocytopenia or prolonging bleeding time. Furthermore, intramuscular administration of KGDRR achieved a functional half-life 3.5 times longer than that of the clinically used antithrombotic eptifibatide at equivalent antithrombotic efficacy. In conclusion, KGDRR exhibits potent antithrombotic activity with a favorable safety profile and enhanced pharmacokinetic stability. These findings position KGDRR as a promising next generation αIIbβ3 antagonist with the potential to improve clinical outcomes in antithrombotic therapy.