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

Cancer Immunol Immunother. 2013 Aug;62(8):1347-57. doi: 10.1007/s00262-013-1437-3. Epub 2013 May 18.

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.

Discussion: 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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibodies, Monoclonal, Humanized / immunology*
  • Antibodies, Monoclonal, Humanized / pharmacology
  • Antibody-Dependent Cell Cytotoxicity / drug effects
  • Antibody-Dependent Cell Cytotoxicity / immunology*
  • Antigens, CD / immunology
  • Antigens, CD / metabolism
  • Antineoplastic Agents / immunology
  • Antineoplastic Agents / pharmacology
  • B7-1 Antigen / immunology
  • B7-1 Antigen / metabolism
  • B7-2 Antigen / immunology
  • B7-2 Antigen / metabolism
  • Benzazepines / immunology
  • Benzazepines / pharmacology
  • CD8-Positive T-Lymphocytes / immunology*
  • CD8-Positive T-Lymphocytes / metabolism
  • Cell Line, Tumor
  • Cells, Cultured
  • Cetuximab
  • Coculture Techniques
  • Cross-Priming / immunology
  • Dendritic Cells / immunology*
  • Dendritic Cells / metabolism
  • Enzyme-Linked Immunosorbent Assay
  • ErbB Receptors / immunology
  • ErbB Receptors / metabolism
  • Flow Cytometry
  • Head and Neck Neoplasms / immunology
  • Head and Neck Neoplasms / metabolism
  • Head and Neck Neoplasms / pathology
  • Humans
  • Immunoglobulins / immunology
  • Immunoglobulins / metabolism
  • Interferon-gamma / immunology
  • Interferon-gamma / metabolism
  • Interleukin-12 Subunit p40 / immunology
  • Interleukin-12 Subunit p40 / metabolism
  • Killer Cells, Natural / immunology*
  • Killer Cells, Natural / metabolism
  • Membrane Glycoproteins / immunology
  • Membrane Glycoproteins / metabolism
  • Toll-Like Receptor 8 / agonists
  • Toll-Like Receptor 8 / immunology*
  • Toll-Like Receptor 8 / metabolism
  • Tumor Necrosis Factor-alpha / immunology
  • Tumor Necrosis Factor-alpha / metabolism

Substances

  • Antibodies, Monoclonal, Humanized
  • Antigens, CD
  • Antineoplastic Agents
  • B7-1 Antigen
  • B7-2 Antigen
  • Benzazepines
  • CD83 antigen
  • Immunoglobulins
  • Interleukin-12 Subunit p40
  • Membrane Glycoproteins
  • TLR8 protein, human
  • Toll-Like Receptor 8
  • Tumor Necrosis Factor-alpha
  • VTX-2337
  • Interferon-gamma
  • ErbB Receptors
  • Cetuximab