A bispecific diabody that mediates natural killer cell cytotoxicity against xenotransplantated human Hodgkin's tumors.

CD16/CD30 bispecific monoclonal antibodies can induce remissions of Hodgkin's disease refractory to chemo- and radiotherapy. However, the development of human antimouse immunoglobulin antibodies and allergic reactions precludes repeated applications of the antibody. Moreover, problems of producing and purifying sufficient amounts of material limit the clinical practicability of this novel treatment approach. To overcome these obstacles, we have constructed a bispecific antibody in a diabody form that only employs the variable domains of the CD16/CD30 hybrid hybridoma. The diabody compared favorably with the parent CD16/CD30 bispecific antibody in its ability to activate and target natural killer cells in vitro. Its administration to mice bearing xenografted Hodgkin's lymphoma resulted in a marked regression of tumor growth, thus proving for the first time the capability of a diabody for immune recruitment in vivo. The CD16/CD30 diabody is a novel reagent that should considerably facilitate the immunotherapy of patients with refractory Hodgkin's lymphoma.