Barbon E, Ayme G, Mohamadi A, Ottavi J, Kawecki C, Casari C, Verhenne S, Marmier S, van Wittenberghe L, Charles S, Collaud F, Denis CV, Christophe OD, Mingozzi F, Lenting PJ. Single-domain antibodies targeting antithrombin reduce bleeding in hemophilic mice with or without inhibitors.
EMBO Mol Med 2020;
12:e11298. [PMID:
32159286 PMCID:
PMC7136963 DOI:
10.15252/emmm.201911298]
[Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 02/14/2020] [Accepted: 02/18/2020] [Indexed: 01/08/2023] Open
Abstract
Novel therapies for hemophilia, including non-factor replacement and in vivo gene therapy, are showing promising results in the clinic, including for patients having a history of inhibitor development. Here, we propose a novel therapeutic approach for hemophilia based on llama-derived single-domain antibody fragments (sdAbs) able to restore hemostasis by inhibiting the antithrombin (AT) anticoagulant pathway. We demonstrated that sdAbs engineered in multivalent conformations were able to block efficiently AT activity in vitro, restoring the thrombin generation potential in FVIII-deficient plasma. When delivered as a protein to hemophilia A mice, a selected bi-paratopic sdAb significantly reduced the blood loss in a model of acute bleeding injury. We then packaged this sdAb in a hepatotropic AAV8 vector and tested its safety and efficacy profile in hemophilic mouse models. We show that the long-term expression of the bi-paratopic sdAb in the liver is safe and poorly immunogenic, and results in sustained correction of the bleeding phenotype in hemophilia A and B mice, even in the presence of inhibitory antibodies to the therapeutic clotting factor.
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