title: Structure-guided residence time optimization of a dabigatran reversal agent.
abstract: Novel oral anticoagulants are effective and safe alternatives to vitamin-K antagonists for anticoagulation therapy. However, anticoagulation therapy in general is associated with an elevated risk of bleeding. Idarucizumab is a reversal agent for the direct thrombin inhibitor, dabigatran etexilate (Pradaxa®) and is currently in Phase 3 studies. Here, we report data on the antibody fragment aDabi-Fab2, a putative backup molecule for idarucizumab. Although aDabi-Fab2 completely reversed effects of dabigatran in a rat model in vivo, we observed significantly reduced duration of action compared to idarucizumab. Rational protein engineering, based on the X-ray structure of aDabi-Fab2, led to the identification of mutant Y103W. The mutant had optimized shape complementarity to dabigatran while maintaining an energetically favored hydrogen bond. It displayed increased affinity for dabigatran, mainly driven by a slower off-rate. Interestingly, the increased residence time translated into longer duration of action in vivo. It was thus possible to further enhance the efficacy of aDabi-Fab2 based on rational design, giving it the potential to serve as a back-up candidate for idarucizumab.
authors.affiliation: a New Biological Entities Discovery; Boehringer Ingelheim GmbH & Co. KG ; Biberach , Germany.
authors.forename: Felix
authors.initials: F
authors.lastname: Schiele
authors.forename: Joanne
authors.initials: J
authors.lastname: van Ryn
authors.forename: Tobias
authors.initials: T
authors.lastname: Litzenburger
authors.forename: Michael
authors.initials: M
authors.lastname: Ritter
authors.forename: Daniel
authors.initials: D
authors.lastname: Seeliger
authors.forename: Herbert
authors.initials: H
authors.lastname: Nar
mesh_terms: D000818:Animals; D061067:Antibodies, Monoclonal, Humanized / Q000737:chemistry / Q000494:pharmacology; D000915:Antibody Affinity; D018360:Crystallography, X-Ray; D000069604:Dabigatran / Q000037:antagonists & inhibitors*; D004195:Disease Models, Animal; D015195:Drug Design; D004797:Enzyme-Linked Immunosorbent Assay; D007140:Immunoglobulin Fab Fragments / Q000737:chemistry* / Q000494:pharmacology*; D011487:Protein Conformation; D051381:Rats; D017208:Rats, Wistar; D013918:Thrombin Time
chemical_list: D061067:Antibodies, Monoclonal, Humanized; D007140:Immunoglobulin Fab Fragments; C000594745:idarucizumab; D000069604:Dabigatran
keywords: Pradaxa; antidote; idarucizumab; rational protein design; residence time; thrombin