title: Monovalent IgG4 molecules: immunoglobulin Fc mutations that result in a monomeric structure.
abstract: Antibodies have become the fastest growing class of biological therapeutics, in part due to their exquisite specificity and ability to modulate protein-protein interactions with a high biological potency. The relatively large size and bivalency of antibodies, however, limits their use as therapeutics in certain circumstances. Antibody fragments, such as single-chain variable fragments and antigen binding-fragments, have emerged as viable alternatives, but without further modifications these monovalent formats have reduced terminal serum half-lives because of their small size and lack of an Fc domain, which is required for FcRn-mediated recycling. Using rational engineering of the IgG4 Fc domain to disrupt key interactions at the CH3-CH3 interface, we identified a number of point mutations that abolish Fc dimerization and created half-antibodies, a novel monovalent antibody format that retains a monomeric Fc domain. Introduction of these mutations into an IgG1 framework also led to the creation of half-antibodies. These half-antibodies were shown to be soluble, thermodynamically stable and monomeric, characteristics that are favorable for use as therapeutic proteins. Despite significantly reduced FcRn binding in vitro, which suggests that avidity gains in a dimeric Fc are critical to optimal FcRn binding, this format demonstrated an increased terminal serum half-life compared with that expected for most alternative antibody fragments.
authors.affiliation: MedImmune Ltd.; Department of Antibody Discovery and Protein Engineering; Cambridge, UK.
authors.forename: Ian C
authors.initials: IC
authors.lastname: Wilkinson
authors.affiliation: MedImmune Ltd.; Department of Antibody Discovery and Protein Engineering; Cambridge, UK.
authors.forename: Susan B
authors.initials: SB
authors.lastname: Fowler
authors.affiliation: MedImmune LLC.; Departments of Antibody Discovery and Protein Engineering and Analytical Biochemistry; Gaithersburg, MD USA.
authors.forename: Leeann
authors.initials: L
authors.lastname: Machiesky
authors.affiliation: MedImmune LLC.; Departments of Antibody Discovery and Protein Engineering and Analytical Biochemistry; Gaithersburg, MD USA.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Miller
authors.affiliation: MedImmune LLC.; Departments of Antibody Discovery and Protein Engineering and Analytical Biochemistry; Gaithersburg, MD USA.
authors.forename: David B
authors.initials: DB
authors.lastname: Hayes
authors.affiliation: MedImmune LLC.; Departments of Antibody Discovery and Protein Engineering and Analytical Biochemistry; Gaithersburg, MD USA.
authors.forename: Morshed
authors.initials: M
authors.lastname: Adib
authors.affiliation: MedImmune LLC.; Departments of Antibody Discovery and Protein Engineering and Analytical Biochemistry; Gaithersburg, MD USA.
authors.forename: Cheng
authors.initials: C
authors.lastname: Her
authors.affiliation: MedImmune LLC.; Departments of Antibody Discovery and Protein Engineering and Analytical Biochemistry; Gaithersburg, MD USA.
authors.forename: M Jack
authors.initials: MJ
authors.lastname: Borrok
authors.affiliation: MedImmune LLC.; Departments of Antibody Discovery and Protein Engineering and Analytical Biochemistry; Gaithersburg, MD USA.
authors.forename: Ping
authors.initials: P
authors.lastname: Tsui
authors.affiliation: MedImmune Ltd.; Department of Antibody Discovery and Protein Engineering; Cambridge, UK.
authors.forename: Matthew
authors.initials: M
authors.lastname: Burrell
authors.affiliation: MedImmune Ltd.; Department of Antibody Discovery and Protein Engineering; Cambridge, UK.
authors.forename: Dominic J
authors.initials: DJ
authors.lastname: Corkill
authors.affiliation: MedImmune Ltd.; Department of Antibody Discovery and Protein Engineering; Cambridge, UK.
authors.forename: Susanne
authors.initials: S
authors.lastname: Witt
authors.affiliation: MedImmune Ltd.; Department of Antibody Discovery and Protein Engineering; Cambridge, UK.
authors.forename: David C
authors.initials: DC
authors.lastname: Lowe
authors.affiliation: MedImmune Ltd.; Department of Antibody Discovery and Protein Engineering; Cambridge, UK.
authors.forename: Carl I
authors.initials: CI
authors.lastname: Webster
mesh_terms: D000818:Animals; D006207:Half-Life; D015395:Histocompatibility Antigens Class I / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D007074:Immunoglobulin G / Q000008:administration & dosage / Q000737:chemistry / Q000235:genetics*; D051379:Mice; D008807:Mice, Inbred BALB C; D009154:Mutation / Q000235:genetics*; D011485:Protein Binding / Q000187:drug effects; D015202:Protein Engineering; D055550:Protein Stability / Q000187:drug effects; D017434:Protein Structure, Tertiary / Q000187:drug effects / Q000235:genetics; D011961:Receptors, Fc / Q000737:chemistry / Q000235:genetics*; D011993:Recombinant Fusion Proteins / Q000008:administration & dosage / Q000737:chemistry / Q000235:genetics*; D057127:Single-Chain Antibodies / Q000008:administration & dosage / Q000737:chemistry / Q000235:genetics*
chemical_list: D015395:Histocompatibility Antigens Class I; D007074:Immunoglobulin G; D011961:Receptors, Fc; D011993:Recombinant Fusion Proteins; D057127:Single-Chain Antibodies; C100688:Fc receptor, neonatal
keywords: Antibody engineering; FcRn; half-antibody; half-life extension; monomeric Fc