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.
Grosse-Hovest
Ludger
L
Institute for Cell Biology, Department of Immunology, University of Tübingen, Tübingen, Germany.
Hartlapp
Ingo
I
Marwan
Wolfgang
W
Brem
Gottfried
G
Rammensee
Hans-Georg
HG
Jung
Gundram
G
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