A recombinant bispecific single-chain antibody induces targeted, supra-agonistic CD28-stimulation and tumor cell killing.
Endowing tumor cells with costimulatory signals for T cell activation has emerged as a promising strategy for tumor immunotherapy. Costimulatory molecules were either transfected into tumor cells to generate vaccines or were fused, e.g. to antibodies against tumor-associated antigens, to achieve targeted T cell costimulation in vivo. Here we report the production and purification of rM28, a recombinant bispecific single-chain antibody directed to a melanoma-associated proteoglycan and to the costimulatory CD28 molecule on human T cells. We found that a dimer of the recombinant molecule, bound to tumor target cells, induced pronounced T cell activation in peripheral blood mononuclear cell preparations without additional TCR/CD3 stimulation being required. The lytic activity generated after 3 days of stimulation effectively prevented tumor cell growth. However, it was unspecific and predominantly mediated by non T cells. Our findings demonstrate that presentation of a CD28 antibody within a suitable recombinant, bispecific format may result in a "targeted supra-agonistic stimulation" of the CD28 molecule, which leads to effective tumor cell killing after induction of unspecifically lytic cells.
Institute for Cell Biology, Department of Immunology, University of Tübingen, Tübingen, Germany.
Ludger
L
Grosse-Hovest
Ingo
I
Hartlapp
Wolfgang
W
Marwan
Gottfried
G
Brem
Hans-Georg
HG
Rammensee
Gundram
G
Jung
D018033:Antibodies, Bispecific / Q000276:immunology* / Q000627:therapeutic use; D018106:CD28 Antigens / Q000276:immunology*; D003602:Cytotoxicity, Immunologic; D006801:Humans; D008213:Lymphocyte Activation; D008545:Melanoma / Q000276:immunology* / Q000628:therapy*; D011509:Proteoglycans / Q000276:immunology*; D011994:Recombinant Proteins / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology; D014407:Tumor Cells, Cultured
D018033:Antibodies, Bispecific; D018106:CD28 Antigens; D011509:Proteoglycans; D011994:Recombinant Proteins