title: A novel antibody-4-1BBL fusion protein for targeted costimulation in cancer immunotherapy.
abstract: Costimulation is an essential step in T-cell activation and hence, represents an important aspect in cancer immunotherapy. 4-1BB, a member of the tumor necrosis factor receptor family, has gained particular interest as a costimulatory molecule. Here, we investigated the potential of a targeted activation of 4-1BB-mediated costimulation at the tumor site by generating a recombinant antibody-cytokine fusion protein composed of a single-chain antibody fragment (scFv36) specific for the tumor stromal antigen fibroblast activation protein (FAP) and the extracellular domain of the 4-1BB ligand (4-1BBL). The scFv36-4-1BBL fusion protein is a homotrimeric molecule that binds specifically to FAP and the receptor 4-1BB. T-cell costimulation was demonstrated by interferon-gamma release of peripheral blood mononuclear cells cocultured with FAP-expressing HT1080 cells upon T-cell receptor triggering by monoclonal anti-CD3 antibody. Costimulatory activity of the scFv36-4-1BBL fusion protein was concentration dependent, ligand-specific, and substantially constrained to FAP-expressing target cell binding. Furthermore, scFv36-4-1BBL enhanced T-cell activation when the bispecific antibody scDb33CD3 (specific for FAP and CD3) was used as primary stimulus. Thus, target cell-dependent costimulation with scFv36-4-1BBL constitutes a new option to enhance T-cell activation by bispecific antibodies or antigen-dependent T-cell receptor triggering and should be useful to improve T cell-mediated antitumor responses.
authors.affiliation: Institut für Zellbiologie und Immunologie, Universität Stuttgart, Stuttgart, Germany. dafne.mueller@izi.uni-stuttgart.de
authors.forename: Dafne
authors.initials: D
authors.lastname: Müller
authors.forename: Katharina
authors.initials: K
authors.lastname: Frey
authors.forename: Roland E
authors.initials: RE
authors.lastname: Kontermann
mesh_terms: D053330:4-1BB Ligand / Q000235:genetics / Q000276:immunology* / Q000627:therapeutic use; D000951:Antigens, Neoplasm / Q000276:immunology*; D014408:Biomarkers, Tumor / Q000276:immunology*; D045744:Cell Line, Tumor; D010450:Endopeptidases; D018093:Gelatinases; D006801:Humans; D007135:Immunoglobulin Variable Region / Q000235:genetics / Q000276:immunology* / Q000627:therapeutic use; D007167:Immunotherapy; D008213:Lymphocyte Activation; D008565:Membrane Proteins; D009369:Neoplasms / Q000628:therapy*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology* / Q000627:therapeutic use; D012697:Serine Endopeptidases / Q000276:immunology*; D014162:Transfection; D053261:Tumor Necrosis Factor Receptor Superfamily, Member 9 / Q000276:immunology; D000099167:Fibroblast Activation Protein Alpha
chemical_list: D053330:4-1BB Ligand; D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; D010450:Endopeptidases; D018093:Gelatinases; D007135:Immunoglobulin Variable Region; D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins; D012697:Serine Endopeptidases; D053261:Tumor Necrosis Factor Receptor Superfamily, Member 9; D000099167:Fibroblast Activation Protein Alpha