title: Structural Characterisation Reveals Mechanism of IL-13-Neutralising Monoclonal Antibody Tralokinumab as Inhibition of Binding to IL-13Rα1 and IL-13Rα2.
abstract: Interleukin (IL)-13 is a pleiotropic T helper type 2 cytokine frequently associated with asthma and atopic dermatitis. IL-13-mediated signalling is initiated by binding to IL-13Rα1, which then recruits IL-4Rα to form a heterodimeric receptor complex. IL-13 also binds to IL-13Rα2, considered as either a decoy or a key mediator of fibrosis. IL-13-neutralising antibodies act by preventing IL-13 binding to IL-13Rα1, IL-4Rα and/or IL-13Rα2. Tralokinumab (CAT-354) is an IL-13-neutralising human IgG4 monoclonal antibody that has shown clinical benefit in patients with asthma. To decipher how tralokinumab inhibits the effects of IL-13, we determined the structure of tralokinumab Fab in complex with human IL-13 to 2 Å resolution. The structure analysis reveals that tralokinumab prevents IL-13 from binding to both IL-13Rα1 and IL-13Rα2. This is supported by biochemical ligand-receptor interaction assay data. The tralokinumab epitope is mainly composed of residues in helices D and A of IL-13. It is mostly light chain complementarity-determining regions that are driving paratope interactions; the variable light complementarity-determining region 2 plays a key role by providing residue contacts for a network of hydrogen bonds and a salt bridge in the core of binding. The key residues within the paratope contributing to binding were identified as Asp50, Asp51, Ser30 and Lys31. This study demonstrates that tralokinumab prevents the IL-13 pharmacodynamic effect by binding to IL-13 helices A and D, thus preventing IL-13 from interacting with IL-13Rα1 and IL-13Rα2.
authors.affiliation: Department of Antibody Discovery and Protein Engineering, MedImmune Ltd., Granta Park, Cambridge CB21 6GH, UK. Electronic address: popovicb@medimmune.com.
authors.forename: B
authors.initials: B
authors.lastname: Popovic
authors.affiliation: Discovery Sciences, Innovative Medicines and Early Development Biotech Unit, AstraZeneca, Cambridge Science Park, Milton Road, Cambridge CB4 0WG, UK.
authors.forename: J
authors.initials: J
authors.lastname: Breed
authors.affiliation: Department of Antibody Discovery and Protein Engineering, MedImmune Ltd., Granta Park, Cambridge CB21 6GH, UK.
authors.forename: D G
authors.initials: DG
authors.lastname: Rees
authors.affiliation: Department of Antibody Discovery and Protein Engineering, MedImmune Ltd., Granta Park, Cambridge CB21 6GH, UK.
authors.forename: M J
authors.initials: MJ
authors.lastname: Gardener
authors.affiliation: Department of Antibody Discovery and Protein Engineering, MedImmune Ltd., Granta Park, Cambridge CB21 6GH, UK.
authors.forename: L M K
authors.initials: LM
authors.lastname: Vinall
authors.affiliation: Department of Antibody Discovery and Protein Engineering, MedImmune Ltd., Granta Park, Cambridge CB21 6GH, UK.
authors.forename: B
authors.initials: B
authors.lastname: Kemp
authors.affiliation: Department of Antibody Discovery and Protein Engineering, MedImmune Ltd., Granta Park, Cambridge CB21 6GH, UK.
authors.forename: J
authors.initials: J
authors.lastname: Spooner
authors.affiliation: Department of Antibody Discovery and Protein Engineering, MedImmune Ltd., Granta Park, Cambridge CB21 6GH, UK.
authors.forename: J
authors.initials: J
authors.lastname: Keen
authors.affiliation: Department of Antibody Discovery and Protein Engineering, MedImmune Ltd., Granta Park, Cambridge CB21 6GH, UK.
authors.forename: R
authors.initials: R
authors.lastname: Minter
authors.affiliation: Department of Biopharmaceutical Development, MedImmune Ltd., Granta Park, Cambridge CB21 6GH, UK.
authors.forename: F
authors.initials: F
authors.lastname: Uddin
authors.affiliation: Inflammation, Neuroscience, Respiratory, Global Medicines Development, AstraZeneca, One MedImmune Way, Gaithersburg, MD 20878, USA.
authors.forename: G
authors.initials: G
authors.lastname: Colice
authors.affiliation: Department of Antibody Discovery and Protein Engineering, MedImmune Ltd., Granta Park, Cambridge CB21 6GH, UK.
authors.forename: T
authors.initials: T
authors.lastname: Wilkinson
authors.affiliation: Department of Antibody Discovery and Protein Engineering, MedImmune Ltd., Granta Park, Cambridge CB21 6GH, UK.
authors.forename: T
authors.initials: T
authors.lastname: Vaughan
authors.affiliation: Department of Respiratory, Inflammation and Autoimmunity, MedImmune Ltd., Granta Park, Cambridge CB21 6GH, UK.
authors.forename: R D
authors.initials: RD
authors.lastname: May
mesh_terms: D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D057134:Antibodies, Neutralizing / Q000494:pharmacology; D001249:Asthma / Q000188:drug therapy; D003001:Cloning, Molecular; D022801:Complementarity Determining Regions / Q000378:metabolism; D018360:Crystallography, X-Ray; D006801:Humans; D020128:Inhibitory Concentration 50; D018793:Interleukin-13 / Q000378:metabolism*; D053661:Interleukin-13 Receptor alpha1 Subunit / Q000378:metabolism*; D053663:Interleukin-13 Receptor alpha2 Subunit / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary
chemical_list: D000911:Antibodies, Monoclonal; D057134:Antibodies, Neutralizing; D022801:Complementarity Determining Regions; D018793:Interleukin-13; D053661:Interleukin-13 Receptor alpha1 Subunit; D053663:Interleukin-13 Receptor alpha2 Subunit; C574065:tralokinumab
keywords: antibody structure; antibody–antigen complex; crystal structure; mutagenesis; tralokinumab