title: In vivo tumor targeting and imaging with engineered trivalent antibody fragments containing collagen-derived sequences.
abstract: There is an urgent need to develop new and effective agents for cancer targeting. In this work, a multivalent antibody is characterized in vivo in living animals. The antibody, termed "trimerbody", comprises a single-chain antibody (scFv) fragment connected to the N-terminal trimerization subdomain of collagen XVIII NC1 by a flexible linker. As indicated by computer graphic modeling, the trimerbody has a tripod-shaped structure with three highly flexible scFv heads radially outward oriented. Trimerbodies are trimeric in solution and exhibited multivalent binding, which provides them with at least a 100-fold increase in functional affinity than the monovalent scFv. Our results also demonstrate the feasibility of producing functional bispecific trimerbodies, which concurrently bind two different ligands. A trimerbody specific for the carcinoembryonic antigen (CEA), a classic tumor-associated antigen, showed efficient tumor targeting after systemic administration in mice bearing CEA-positive tumors. Importantly, a trimerbody that recognizes an angiogenesis-associated laminin epitope, showed excellent tumor localization in several cancer types, including fibrosarcomas and carcinomas. These results illustrate the potential of this new antibody format for imaging and therapeutic applications, and suggest that some laminin epitopes might be universal targets for cancer targeting.
authors.affiliation: Molecular Immunology Unit, Hospital Universitario Puerta de Hierro, Madrid, Spain.
authors.forename: Angel M
authors.initials: AM
authors.lastname: Cuesta
authors.forename: David
authors.initials: D
authors.lastname: Sánchez-Martín
authors.forename: Laura
authors.initials: L
authors.lastname: Sanz
authors.forename: Jaume
authors.initials: J
authors.lastname: Bonet
authors.forename: Marta
authors.initials: M
authors.lastname: Compte
authors.forename: Leonor
authors.initials: L
authors.lastname: Kremer
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Blanco
authors.forename: Baldomero
authors.initials: B
authors.lastname: Oliva
authors.forename: Luis
authors.initials: L
authors.lastname: Alvarez-Vallina
mesh_terms: D000818:Animals; D000912:Antibodies, Neoplasm / Q000737:chemistry / Q000235:genetics; D002272:Carcinoembryonic Antigen / Q000276:immunology; D002460:Cell Line; D045744:Cell Line, Tumor; D043170:Collagen Type XVIII / Q000737:chemistry / Q000235:genetics; D003198:Computer Simulation; D000939:Epitopes; D005260:Female; D005456:Fluorescent Dyes; D006367:HeLa Cells; D006801:Humans; D007128:Immunoglobulin Fragments / Q000737:chemistry / Q000235:genetics; D007797:Laminin / Q000276:immunology; D051379:Mice; D008819:Mice, Nude; D008958:Models, Molecular; D009368:Neoplasm Transplantation; D009374:Neoplasms, Experimental / Q000175:diagnosis* / Q000276:immunology*; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics; D015202:Protein Engineering; D020836:Protein Structure, Quaternary; D014183:Transplantation, Heterologous
chemical_list: D000912:Antibodies, Neoplasm; D002272:Carcinoembryonic Antigen; D043170:Collagen Type XVIII; D000939:Epitopes; D005456:Fluorescent Dyes; D007128:Immunoglobulin Fragments; D007797:Laminin; D010446:Peptide Fragments