title: TLR8 stimulation enhances cetuximab-mediated natural killer cell lysis of head and neck cancer cells and dendritic cell cross-priming of EGFR-specific CD8+ T cells.
abstract: BACKGROUND
  Cetuximab is an anti-epidermal growth factor receptor (EGFR) monoclonal antibody that prolongs survival in the treatment for head and neck cancer (HNC), but only in 10-20 % of patients. An immunological mechanism of action such as natural killer (NK) cell-mediated antibody-dependent cellular cytotoxicity (ADCC) has been suggested. We investigated the effects of activating toll-like receptor (TLR)-8 to enhance activity of cetuximab-stimulated, FcγR-bearing cells.
  
  
  OBJECTIVE
  To determine the capability of TLR8-stimulation to enhance the activation and function of NK cells and dendritic cells (DC) in the presence of cetuximab-coated HNC cells.
  
  
  METHODS
  Peripheral blood mononuclear cells (PBMC), NK, DC, and CD8(+) T cells were isolated and analyzed using (51)Cr release ADCC, flow cytometry analysis, cytokine ELISA, and EGFR853-861 tetramer staining.
  
  
  RESULTS
  TLR8 stimulation of unfractionated PBMC led to enhanced cetuximab-mediated ADCC in healthy donors (p < 0.01) and HNC patients (p < 0.001), which was dependent on NK cells. Secretion of Th1 cytokines TNFα (p < 0.0001), IFNγ (p < 0.0001), and IL-12p40 (p < 0.005) was increased. TLR8 stimulation of PBMC augmented cetuximab-enhanced NK cell degranulation (p < 0.001). TLR8-stimulated NK cells enhanced DC maturation markers CD80, CD83, and CD86 in co-culture with cetuximab-treated HNC cells. TLR8 stimulation of NK-DC co-cultures significantly increased DC priming of EGFR-specific CD8(+) T cells in the presence of cetuximab.
  
  
  CONCLUSIONS
  VTX-2337 and cetuximab combination therapy can activate innate and adaptive anti-cancer immune responses. Further investigation in human trials will be important for determining the clinical benefit of this combination and for determining biomarkers of response.
authors.affiliation: Department of Otolaryngology, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: Ryan M
authors.initials: RM
authors.lastname: Stephenson
authors.forename: Chwee Ming
authors.initials: CM
authors.lastname: Lim
authors.forename: Maura
authors.initials: M
authors.lastname: Matthews
authors.forename: Gregory
authors.initials: G
authors.lastname: Dietsch
authors.forename: Robert
authors.initials: R
authors.lastname: Hershberg
authors.forename: Robert L
authors.initials: RL
authors.lastname: Ferris
mesh_terms: D061067:Antibodies, Monoclonal, Humanized / Q000276:immunology* / Q000494:pharmacology; D000920:Antibody-Dependent Cell Cytotoxicity / Q000187:drug effects / Q000276:immunology*; D015703:Antigens, CD / Q000276:immunology / Q000378:metabolism; D000970:Antineoplastic Agents / Q000276:immunology / Q000494:pharmacology; D018122:B7-1 Antigen / Q000276:immunology / Q000378:metabolism; D051940:B7-2 Antigen / Q000276:immunology / Q000378:metabolism; D001552:Benzazepines / Q000276:immunology / Q000494:pharmacology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D000068818:Cetuximab; D018920:Coculture Techniques; D045142:Cross-Priming / Q000276:immunology; D003713:Dendritic Cells / Q000276:immunology* / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D066246:ErbB Receptors / Q000276:immunology / Q000378:metabolism; D005434:Flow Cytometry; D006258:Head and Neck Neoplasms / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007136:Immunoglobulins / Q000276:immunology / Q000378:metabolism; D007371:Interferon-gamma / Q000276:immunology / Q000378:metabolism; D053762:Interleukin-12 Subunit p40 / Q000276:immunology / Q000378:metabolism; D007694:Killer Cells, Natural / Q000276:immunology* / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000276:immunology / Q000378:metabolism; D051200:Toll-Like Receptor 8 / Q000819:agonists / Q000276:immunology* / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology / Q000378:metabolism; D000097802:CD83 Antigen
chemical_list: D061067:Antibodies, Monoclonal, Humanized; D015703:Antigens, CD; D000970:Antineoplastic Agents; D018122:B7-1 Antigen; D051940:B7-2 Antigen; D001552:Benzazepines; D000068818:Cetuximab; D066246:ErbB Receptors; D007136:Immunoglobulins; D007371:Interferon-gamma; D053762:Interleukin-12 Subunit p40; D008562:Membrane Glycoproteins; D051200:Toll-Like Receptor 8; D014409:Tumor Necrosis Factor-alpha; D000097802:CD83 Antigen; C495349:TLR8 protein, human; C573973:VTX-2337