title: Anti-carcinoembryonic antigen single-chain variable fragment antibody variants bind mouse and human neonatal Fc receptor with different affinities that reveal distinct cross-species differences in serum half-life.
abstract: Serum half-life of IgG is controlled by the neonatal Fc receptor (FcRn) that interacts with the IgG Fc region and may be increased or decreased as a function of altered FcRn binding. Preclinical evaluations of modified IgGs are frequently carried out in mice, but such IgGs may bind differently to mouse and human FcRn (mFcRn and hFcRn). Here, we report a detailed characterization of a matched set of mouse-human chimeric T84.66 scFv-Fc variants with specificity for the tumor carcinoembryonic antigen and mutations in the FcRn-binding site. Binding to soluble mFcRn and hFcRn was measured using in vitro assays, and the results were compared with blood clearance in vivo in normal (mFcRn bearing) and hFcRn transgenic mice. All variants bound better to mFcRn than to hFcRn. The loss of affinity varied among the mutants, however, and also the hierarchy of binding differed depending on the receptor. The mutations had no major impact on binding to the classical Fcγ receptors. Importantly, the trend of blood clearance in both strains of mice correlated with the hierarchy of binding obtained using soluble FcRn. Consequently, in vitro interaction analysis of engineered IgGs regarding their cross-species FcRn binding ability provides information for prediction of in vivo pharmacokinetics.
authors.affiliation: Centre for Immune Regulation and Department of Molecular Biosciences, University of Oslo, N-0316 Oslo, Norway. j.t.andersen@imbv.uio.no
authors.forename: Jan Terje
authors.initials: JT
authors.lastname: Andersen
authors.forename: Stian
authors.initials: S
authors.lastname: Foss
authors.forename: Vania E
authors.initials: VE
authors.lastname: Kenanova
authors.forename: Tove
authors.initials: T
authors.lastname: Olafsen
authors.forename: Ingvild S
authors.initials: IS
authors.lastname: Leikfoss
authors.forename: Derry C
authors.initials: DC
authors.lastname: Roopenian
authors.forename: Anna M
authors.initials: AM
authors.lastname: Wu
authors.forename: Inger
authors.initials: I
authors.lastname: Sandlie
mesh_terms: D000818:Animals; D000918:Antibody Specificity; D002272:Carcinoembryonic Antigen / Q000276:immunology*; D003429:Cross Reactions / Q000276:immunology; D015395:Histocompatibility Antigens Class I / Q000276:immunology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology*; D007457:Iodine Radioisotopes; D051379:Mice; D008807:Mice, Inbred BALB C; D008822:Mice, Transgenic; D015202:Protein Engineering / Q000379:methods*; D011961:Receptors, Fc / Q000276:immunology*; D017452:Receptors, IgG / Q000276:immunology*; D057127:Single-Chain Antibodies / Q000276:immunology* / Q000493:pharmacokinetics; D013045:Species Specificity
chemical_list: D002272:Carcinoembryonic Antigen; D015395:Histocompatibility Antigens Class I; D007074:Immunoglobulin G; D007457:Iodine Radioisotopes; D011961:Receptors, Fc; D017452:Receptors, IgG; D057127:Single-Chain Antibodies; C100688:Fc receptor, neonatal