Activated vitronectin as a target for anticancer therapy with human antibodies.
The formation of a provisional extracellular matrix represents an important step during tumor growth and angiogenesis. Proteins that participate in this process become activated and undergo conformational changes that expose biologically active cryptic sites. Activated matrix proteins express epitopes not found on their native counterparts. We hypothesized that these epitopes may have a restricted tissue distribution, rendering them suitable targets for therapeutic human monoclonal antibodies (huMabs). In this study, we exploited phage antibody display technology and subtractive phage selection to generate human monoclonal antibody fragments that discriminate between the activated and native conformation of the extracellular matrix protein vitronectin. One of the selected antibody fragments, scFv VN18, was used to construct a fully human IgG/kappa monoclonal antibody with an affinity of 9.3 nM. In immunohistochemical analysis, scFv and huMab VN18 recognized activated vitronectin in tumor tissues, whereas hardly any activated vitronectin was detectable in normal tissues. Iodine 123-radiolabeled huMabVN18 was shown to target to Rous sarcoma virus-induced tumors in chickens, an animal model in which the epitope for huMab VN18 is exposed during tumor development. Our results establish activated vitronectin as a potential target for tumor therapy in humans.
Bloemendal
Haiko J
HJ
Department of Medical Oncology, University Medical Center Utrecht, Heidelberglaan 100, HP F02.126, 3584 CX Utrecht, The Netherlands.
de Boer
Hetty C
HC
Koop
Elianne A
EA
van Dongen
Alice J
AJ
Goldschmeding
Roel
R
Landman
Wil J M
WJ
Logtenberg
Ton
T
Gebbink
Martijn F B G
MF
Voest
Emile E
EE
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000627:therapeutic use*; D001358:Avian Sarcoma Viruses / Q000472:pathogenicity*; D001666:Binding Sites, Antibody; D002645:Chickens; D003110:Colonic Neoplasms / Q000276:immunology / Q000628:therapy; D004797:Enzyme-Linked Immunosorbent Assay; D018604:Epitope Mapping; D006801:Humans; D007128:Immunoglobulin Fragments / Q000276:immunology; D007135:Immunoglobulin Variable Region; D007457:Iodine Radioisotopes; D008546:Melanoma, Experimental / Q000276:immunology / Q000628:therapy; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008819:Mice, Nude; D010446:Peptide Fragments / Q000276:immunology; D019151:Peptide Library; D011201:Poultry Diseases / Q000000981:diagnostic imaging / Q000276:immunology / Q000628:therapy*; D011487:Protein Conformation; D016719:Radioimmunodetection; D001357:Sarcoma, Avian / Q000000981:diagnostic imaging / Q000276:immunology / Q000628:therapy*; D019096:Vitronectin / Q000276:immunology*
D000911:Antibodies, Monoclonal; D007128:Immunoglobulin Fragments; D007135:Immunoglobulin Variable Region; D007457:Iodine Radioisotopes; D010446:Peptide Fragments; D019151:Peptide Library; D019096:Vitronectin