title: A novel tri-functional antibody fusion protein with improved pharmacokinetic properties generated by fusing a bispecific single-chain diabody with an albumin-binding domain from streptococcal protein G.
abstract: The therapeutic application of small recombinant antibody molecules is often limited by a short serum half-life. In order to improve the pharmacokinetic properties, we have investigated a strategy utilizing fusion with an albumin-binding domain (ABD) from streptococcal protein G. This strategy was applied to a bispecific single-chain diabody (scDb CEACD3) developed for the retargeting of cytotoxic T cells to CEA-expressing tumor cells. This novel tri-functional fusion protein (scDb-ABD) was expressed in mammalian cells and recognized both antigens as well as human and mouse serum albumin. scDb-ABD was capable to retarget T cells to CEA-expressing target cells in vitro and to activate the effector cells as measured by stimulation of IL-2 release. Although activity was reduced 3-fold compared with scDb and further reduced 4-fold in the presences of human serum albumin, this assay demonstrated that scDb-ABD is active when exposed to all three antigens. Compared with scDb, the circulation time of scDb-ABD in mice was prolonged 5- to 6-fold similar to a previously described scDb-HSA fusion protein. This strategy, which adds only a small protein domain (46 amino acids) and which utilizes high-affinity, non-covalent albumin interaction, should be broadly applicable to improve serum half-lives of small recombinant antibody molecules.
authors.affiliation: Institut für Zellbiologie und Immunologie, Universität Stuttgart, Allmandring 31, 70569 Stuttgart, Germany.
authors.forename: Roland
authors.initials: R
authors.lastname: Stork
authors.forename: Dafne
authors.initials: D
authors.lastname: Müller
authors.forename: Roland E
authors.initials: RE
authors.lastname: Kontermann
mesh_terms: D000418:Albumins / Q000378:metabolism*; D000818:Animals; D000906:Antibodies / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D000941:Antigens / Q000276:immunology; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007376:Interleukin-2 / Q000378:metabolism; D008213:Lymphocyte Activation / Q000187:drug effects / Q000276:immunology; D051379:Mice; D008958:Models, Molecular; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000737:chemistry* / Q000276:immunology / Q000378:metabolism* / Q000493:pharmacokinetics; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism
chemical_list: D000418:Albumins; D000906:Antibodies; D000941:Antigens; D001426:Bacterial Proteins; C034284:IgG Fc-binding protein, Streptococcus; D007376:Interleukin-2; D011993:Recombinant Fusion Proteins