Generation and characterization of recombinant vascular targeting agents from hybridoma cell lines

Vascular targeting agents (VTAs) can be produced by linking antibodies or a ntibody fragments directed against endothelial cell markers to effector moi eties. So far, it has been necessary to produce the components of VTAs (ant ibody, antibody fragment, linker and effector) separately and subsequently To conjugate them by biochemical reactions. We devised a cloning and expres sion system ro allow rapid generation of recombinant VTAs from hybridoma ce ll lines. The VTAs consist of a single chain Fv antibody fragment as a targ eting moiety and either truncated Pseudomonas exotoxin (resulting in immunt oxins) or truncated human tissue factor (resulting in coaguligands) as effe ctors. The system was applied to generate recombinant immunotoxins and coag uligands directed against endoglin, vascular endothelial growth factor (VEG F): VEGF receptor (VEGFR) complex and vascular cell adhesion molecule I (VC AM-1). The fusion proteins exhibited similar functional activity to analogo us biochemical constructs. This is the first report to describe the generat ion and characterization of recombinant coaguligands.