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      TLR3 agonists improve the immunostimulatory potential of cetuximab against EGFR + head and neck cancer cells

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          Abstract

          Toll-like receptor 3 (TLR3) agonists have been extensively used as adjuvants for anticancer vaccines. However, their immunostimulatory effects and precise mechanisms of action in the presence of antineoplastic monoclonal antibodies (mAbs) have not yet been evaluated. We investigated the effect of TLR3 agonists on cetuximab-mediated antibody-dependent cellular cytotoxicity (ADCC) against head and neck cancer (HNC) cells, as well as on dendritic cell (DC) maturation and cross-priming of epidermal growth factor receptor (EGFR)-specific CD8 + T cells. The cytotoxic activity of peripheral blood mononuclear cells (PBMCs) or isolated natural killer (NK) cells expressing polymorphic variants (at codon 158) of the Fcγ receptor IIIa (FcγIIIa) was determined in 51Cr release assays upon incubation with the TLR3 agonist poly-ICLC. NK cell stimulation was measured based on activation and degranulation markers, while DC maturation in the presence of poly-ICLC was assessed using flow cytometry. The DC-mediated cross priming of EGFR-specific CD8 + T cells was monitored upon in vitro stimulation with tetramer-based flow cytometry. TLR3-stimulated, unfractionated PBMCs from HNC patients mediated robust cetuximab-dependent ADCC, which was abrogated by NK-cell depletion. The cytolytic activity of TLR3-stimulated NK cells differed among cells expressing different polymorphic variants of FcγRIIIa, and NK cells exposed to both poly-ICLC and cetuximab expressed higher levels of CD107a and granzyme B than their counterparts exposed to either stimulus alone. Poly-ICLC plus cetuximab also induced a robust upregulation of CD80, CD83 and CD86 on the surface of DCs, a process that was partially NK-cell dependent. Furthermore, DCs matured in these conditions exhibited improved cross-priming abilities, resulting in higher numbers of EGFR-specific CD8 + T cells. These findings suggest that TLR3 agonists may provide a convenient means to improve the efficacy of mAb-based anticancer regimens.

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          Most cited references36

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          TLR signaling.

          The TLR family senses the molecular signatures of microbial pathogens, and plays a fundamental role in innate immune responses. TLRs signal via a common pathway that leads to the expression of diverse inflammatory genes. In addition, each TLR elicits specific cellular responses to pathogens owing to differential usage of intracellular adapter proteins. Recent studies have revealed the importance of the subcellular localization of TLRs in pathogen recognition and signaling. TLR signaling pathways is negatively regulated by a number of cellular proteins to attenuate inflammation. Here, we describe recent advances in our understanding of the regulation of TLR-mediated signaling.
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            Cetuximab-activated natural killer and dendritic cells collaborate to trigger tumor antigen-specific T-cell immunity in head and neck cancer patients.

            Tumor antigen-specific monoclonal antibodies (mAb) block oncogenic signaling and induce Fcγ receptor (FcγR)-mediated cytotoxicity. However, the role of CD8(+) CTL and FcγR in initiating innate and adaptive immune responses in mAb-treated human patients with cancer is still emerging. FcγRIIIa codon 158 polymorphism was correlated with survival in 107 cetuximab-treated patients with head and neck cancer (HNC). Flow cytometry was carried out to quantify EGF receptor (EGFR)-specific T cells in cetuximab-treated patients with HNC. The effect of cetuximab on natural killer (NK) cell, dendritic cell (DC), and T-cell activation was measured using IFN-γ release assays and flow cytometry. FcγRIIIa polymorphism did not predict clinical outcome in cetuximab-treated patients with HNC; however, elevated circulating EGFR(853-861)-specific CD8(+) T cells were found in cetuximab-treated patients with HNC (P < 0.005). Cetuximab promoted EGFR-specific cellular immunity through the interaction of EGFR(+) tumor cells and FcγRIIIa on NK cells but not on the polymorphism per se. Cetuximab-activated NK cells induced IFN-γ-dependent expression of DC maturation markers, antigen processing machinery components such as TAP-1/2 and T-helper cell (T(H)1) chemokines through NKG2D/MICA binding. Cetuximab initiated adaptive immune responses via NK cell-induced DC maturation, which enhanced cross-presentation to CTL specific for EGFR as well as another tumor antigen, MAGE-3. Cetuximab-activated NK cells promote DC maturation and CD8(+) T-cell priming, leading to tumor antigen spreading and TH1 cytokine release through "NK-DC cross-talk." FcγRIIIa polymorphism did not predict clinical response to cetuximab but was necessary for NK-DC interaction and mAb-induced cross-presentation. EGFR-specific T cells in cetuximab-treated patients with HNC may contribute to clinical response. ©2013 AACR.
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              FCGR2A and FCGR3A polymorphisms associated with clinical outcome of epidermal growth factor receptor expressing metastatic colorectal cancer patients treated with single-agent cetuximab.

              Cetuximab, a chimeric immunoglobulin G 1 (IgG1) anti-epidermal growth factor receptor (EGFR) monoclonal antibody (mAb), has shown efficacy in 10% of patients with metastatic colorectal cancer (CRC). Recent studies demonstrate antibody-dependent cell-mediated cytotoxicity (ADCC) is one of the modes of action for rituximab and trastuzumab. Fragment c (Fc) portion of IgG1 mAb has shown to induce ADCC. Fragment c gamma receptors (FcgammaR) play an important role in initiating ADCC. Studies have shown that two IgG FcgammaR polymorphisms (FCGR2A-H131R and FCGR3A-V158F) independently predict response to rituximab in patients with follicular lymphoma. We tested the hypothesis of whether these two polymorphisms are associated with clinical outcome in metastatic CRC patients treated with single-agent cetuximab. Thirty-nine metastatic CRC patients were enrolled onto the ImClone0144 trial. Using an allele-specific polymerase chain reaction (PCR) -based method, gene polymorphisms of FCGA2A-H131R and FCGA3A-V158F were assessed from genomic DNA extracted from peripheral blood samples. FCGR2A-H131R and FCGR3A-V158F polymorphisms were independently associated with progression-free survival (PFS; P = .037 and .055, respectively; log-rank test). Combined analysis of these two polymorphisms showed that patients with the favorable genotypes (FCGR2A, any histidine allele, and FCGR3A, any phenylalanine allele) showed a median PFS of 3.7 months (95% CI, 2.4 to 4.4 months), whereas patients with any two unfavorable genotypes (FCGR2A arginine/arginine or valine/valine) had a PFS of 1.1 months (95% CI, 1.0 to 1.4 months; P = .004; log-rank test). Our preliminary data suggest that these two polymorphisms may be useful molecular markers to predict clinical outcome in metastatic CRC patients treated with cetuximab and that they may indicate a role of ADCC of cetuximab.
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                Author and article information

                Journal
                Oncoimmunology
                Oncoimmunology
                ONCI
                Oncoimmunology
                Landes Bioscience
                2162-4011
                2162-402X
                01 June 2013
                29 April 2013
                29 April 2013
                : 2
                : 6
                : e24677
                Affiliations
                [1 ]Department of Otolaryngology; University of Pittsburgh Medical Center; Pittsburgh, PA USA
                [2 ]Department of Immunology; University of Pittsburgh Cancer Center; Pittsburgh, PA USA
                [3 ]Department of Otolaryngology-Head and Neck Surgery; National University Health System; Singapore
                [4 ]Oncovir, Inc.; Washington, D.C., USA
                Author notes
                [†]

                These authors contributed equally to this work.

                [* ]Correspondence to: Robert L Ferris, Email: ferrisrl@ 123456upmc.edu
                Article
                2013ONCOIMM0061R 24677
                10.4161/onci.24677
                3716757
                23894722
                bb007a1e-1eaa-4de4-b196-a540b53644ca
                Copyright © 2013 Landes Bioscience

                This is an open-access article licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License. The article may be redistributed, reproduced, and reused for non-commercial purposes, provided the original source is properly cited.

                History
                : 11 March 2013
                : 08 April 2013
                : 12 April 2013
                Categories
                Original Research

                Immunology
                adcc,cetuximab-activated nk cells,cross-priming,egfr-specific cd8+ t cells,poly-iclc,tlr3
                Immunology
                adcc, cetuximab-activated nk cells, cross-priming, egfr-specific cd8+ t cells, poly-iclc, tlr3

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