title: A fibrin-specific monoclonal antibody from a designed phage display library inhibits clot formation and localizes to tumors in vivo.
abstract: Fibrin formation from fibrinogen is a rare process in the healthy organism but is a pathological feature of thrombotic events, cancer and a wide range of inflammatory conditions. We have designed and constructed an antibody phage display library (containing 13 billion clones) for the selective recognition of the N-terminal peptide of fibrin alpha chain. The key structural feature for selective fibrin binding was a K94E mutation in the VH domain. From this library, an antibody was isolated (termed AP2), which recognizes the five N-terminal amino acids of fibrin with high affinity (Kd=44nM), but does not bind to fibrinogen. The AP2 antibody could be expressed in various formats (scFv, small immune protein and IgG) and inhibited fibrin clot formation in a concentration-dependent manner. Moreover, the AP2 antibody stained the fibrin-rich provisional stroma in solid tumors but did not exhibit any detectable staining toward normal tissues. Using a radioiodinated antibody preparation and quantitative biodistribution studies in tumor-bearing mice, AP2 was shown to selectively localize to fibrin-rich F9 murine teratocarcinomas, but not to SKRC-52 human kidney cancer xenografts. Collectively, the experiments indicate that the AP2 antibody recognizes fibrin in vitro and in vivo. The antibody may facilitate the development of fibrin-specific therapeutic agents.
authors: Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, Vladimir-Prelog-Weg 2, CH-8093 Zürich, Switzerland. Electronic address: alessiaputelli@pharma.ethz.ch.
authors: Alessia
authors: A
authors: Putelli
authors: Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, Vladimir-Prelog-Weg 2, CH-8093 Zürich, Switzerland. Electronic address: jkiefer@ethz.ch.
authors: Jonathan D
authors: JD
authors: Kiefer
authors: Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, Vladimir-Prelog-Weg 2, CH-8093 Zürich, Switzerland. Electronic address: zadorym@student.ethz.ch.
authors: Matthias
authors: M
authors: Zadory
authors: Philochem AG, Libernstrasse 3, CH-8112 Otelfingen, Switzerland. Electronic address: mattia.matasci@philochem.ch.
authors: Mattia
authors: M
authors: Matasci
authors: Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, Vladimir-Prelog-Weg 2, CH-8093 Zürich, Switzerland. Electronic address: dario.neri@pharma.ethz.ch.
authors: Dario
authors: D
authors: Neri
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry*; D001777:Blood Coagulation; D045744:Cell Line, Tumor; D005337:Fibrin / Q000737:chemistry*; D005340:Fibrinogen / Q000737:chemistry; D006801:Humans; D007074:Immunoglobulin G / Q000737:chemistry; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D009368:Neoplasm Transplantation; D009369:Neoplasms / Q000737:chemistry / Q000276:immunology*; D019151:Peptide Library; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D020349:Surface Plasmon Resonance; D013927:Thrombosis
chemical_list: D000911:Antibodies, Monoclonal; D007074:Immunoglobulin G; D019151:Peptide Library; D005337:Fibrin; D005340:Fibrinogen
keywords: antibody phage display; fibrin; tumor neovasculature; vascular targeting