title: Fc-optimized NKG2D-Fc constructs induce NK cell antibody-dependent cellular cytotoxicity against breast cancer cells independently of HER2/neu expression status.
abstract: The ability of NK cells to mediate Ab-dependent cellular cytotoxicity (ADCC) largely contributes to the clinical success of antitumor Abs, including trastuzumab, which is approved for the treatment of breast cancer with HER2/neu overexpression. Notably, only ∼25% of breast cancer patients overexpress HER2/neu. Moreover, HER2/neu is expressed on healthy cells, and trastuzumab application is associated with side effects. In contrast, the ligands of the activating immunoreceptor NKG2D (NKG2DL) are selectively expressed on malignant cells. In this study, we took advantage of the tumor-associated expression of NKG2DL by using them as target Ags for NKG2D-IgG1 fusion proteins optimized by amino acid exchange S239D/I332E in their Fc part. Compared to constructs with wild-type Fc parts, fusion proteins carrying the S239D/I332E modification (NKG2D-Fc-ADCC) mediated highly enhanced degranulation, ADCC, and IFN-γ production of NK cells in response to breast cancer cells. NKG2D-Fc-ADCC substantially enhanced NK reactivity also against HER2/neu-low targets that were unaffected by trastuzumab, as both compounds mediated their immunostimulatory effects in strict dependence of target Ag expression levels. Thus, in line with the hierarchically organized potential of the various activating receptors governing NK reactivity and due to its highly increased affinity to CD16, NKG2D-Fc-ADCC potently enhances NK cell reactivity despite the inevitable reduction of activating signals upon binding to NKG2DL. Due to the tumor-restricted expression of NKG2DL, NKG2D-Fc-ADCC may constitute an attractive means for immunotherapy especially of HER2/neu-low or -negative breast cancer.
authors.affiliation: Department of Hematology and Oncology, Eberhard Karls University, D-72076 Tuebingen, Germany; Clinical Collaboration Unit Translational Immunology, German Cancer Consortium and German Cancer Research Center, D-69120 Heidelberg, Germany;
authors.forename: Stefanie
authors.initials: S
authors.lastname: Raab
authors.affiliation: Department of Hematology and Oncology, Eberhard Karls University, D-72076 Tuebingen, Germany; Clinical Collaboration Unit Translational Immunology, German Cancer Consortium and German Cancer Research Center, D-69120 Heidelberg, Germany;
authors.forename: Julia
authors.initials: J
authors.lastname: Steinbacher
authors.affiliation: Department of Hematology and Oncology, Eberhard Karls University, D-72076 Tuebingen, Germany; Clinical Collaboration Unit Translational Immunology, German Cancer Consortium and German Cancer Research Center, D-69120 Heidelberg, Germany;
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Schmiedel
authors.affiliation: Department of Hematology and Oncology, Eberhard Karls University, D-72076 Tuebingen, Germany; Clinical Collaboration Unit Translational Immunology, German Cancer Consortium and German Cancer Research Center, D-69120 Heidelberg, Germany;
authors.forename: Philaretos C
authors.initials: PC
authors.lastname: Kousis
authors.affiliation: Institute for Molecular Medicine, Goethe University, D-60590 Frankfurt am Main, Germany; and.
authors.forename: Alexander
authors.initials: A
authors.lastname: Steinle
authors.affiliation: Department of Immunology, Eberhard Karls University, D-72076 Tuebingen, Germany.
authors.forename: Gundram
authors.initials: G
authors.lastname: Jung
authors.affiliation: Department of Immunology, Eberhard Karls University, D-72076 Tuebingen, Germany.
authors.forename: Ludger
authors.initials: L
authors.lastname: Grosse-Hovest
authors.affiliation: Department of Hematology and Oncology, Eberhard Karls University, D-72076 Tuebingen, Germany; Clinical Collaboration Unit Translational Immunology, German Cancer Consortium and German Cancer Research Center, D-69120 Heidelberg, Germany; Helmut.Salih@med.uni-tuebingen.de.
authors.forename: Helmut R
authors.initials: HR
authors.lastname: Salih
mesh_terms: D061067:Antibodies, Monoclonal, Humanized / Q000494:pharmacology; D000920:Antibody-Dependent Cell Cytotoxicity / Q000276:immunology*; D001943:Breast Neoplasms / Q000276:immunology*; D003602:Cytotoxicity, Immunologic / Q000276:immunology; D005260:Female; D006801:Humans; D007141:Immunoglobulin Fc Fragments / Q000235:genetics / Q000276:immunology*; D007167:Immunotherapy / Q000379:methods; D007371:Interferon-gamma / Q000276:immunology; D007694:Killer Cells, Natural / Q000276:immunology*; D055655:NK Cell Lectin-Like Receptor Subfamily K / Q000235:genetics / Q000276:immunology*; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000096:biosynthesis; D017452:Receptors, IgG / Q000235:genetics / Q000276:immunology; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology; D000068878:Trastuzumab
chemical_list: D061067:Antibodies, Monoclonal, Humanized; D007141:Immunoglobulin Fc Fragments; D007371:Interferon-gamma; D055655:NK Cell Lectin-Like Receptor Subfamily K; D018719:Erb-b2 Receptor Tyrosine Kinases; D017452:Receptors, IgG; D011993:Recombinant Fusion Proteins; D000068878:Trastuzumab; C496124:FCGR3A protein, human; C527085:KLRK1 protein, human; C508053:ERBB2 protein, human