Generation and Characterization of a Diabody Targeting the α(v)β(6) Integrin

The α(v)β(6) integrin is up-regulated in cancer and wound healing but it is not generally expressed in healthy adult tissue. There is increasing evidence that it has a role in cancer progression and will be a useful target for antibody-directed cancer therapies. We report a novel recombinant diabody antibody fragment that targets specifically α(v)β(6) and blocks its function. The diabody was engineered with a C-terminal hexahistidine tag (His tag), expressed in Pichia pastoris and purified by IMAC. Surface plasmon resonance (SPR) analysis of the purified diabody showed affinity in the nanomolar range. Pre-treatment of α(v)β(6)-expressing cells with the diabody resulted in a reduction of cell migration and adhesion to LAP, demonstrating biological function-blocking activity. After radio-labeling, using the His-tag for site-specific attachment of (99m)Tc, the diabody retained affinity and targeted specifically to α(v)β(6)-expressing tumors in mice bearing isogenic α(v)β(6) +/− xenografts. Furthermore, the diabody was specifically internalized into α(v)β(6)-expressing cells, indicating warhead targeting potential. Our results indicate that the new α(v)β(6) diabody has a range of potential applications in imaging, function blocking or targeted delivery/internalization of therapeutic agents.