NK Cell-Dependent Antibody-Mediated Immunotherapy Is Improved In Vitro and In Vivo When Combined with Agonists for Toll-like Receptor 2 in Head and Neck Cancer Models.

Mandy Gruijs,Marijke Stigter-Van Walsum,Cornelis W Tuk,Ruud H Brakenhoff,Richard Van Der Mast,Marjolein Van Egmond,Rieneke Van De Ven,Monique M Van Ostaijen-Ten Dam,Sonja H Ganzevles,Marco W Schilham,C René Leemans,Jantine E Bakema

doi:10.3390/ijms222011057

Abstract

The immunosuppressive character of head and neck cancers may explain the relatively low response rates to antibody therapy targeting a tumor antigen, such as cetuximab, and anti-PD-1 checkpoint inhibition. Immunostimulatory agents that overcome tumor-derived inhibitory signals could augment therapeutic efficacy, thereby enhancing tumor elimination and improving patient survival. Here, we demonstrate that cetuximab treatment combined with immunostimulatory agonists for Toll-like receptor (TLR) 2 induces profound immune responses. Natural killer (NK) cells, isolated from healthy individuals or patients with head and neck cancer, harbored enhanced cytotoxic capacity and increased tumor-killing potential in vitro. Additionally, combination treatment increased the release of several pro-inflammatory cytokines and chemokines by NK cells. Tumor-bearing mice that received cetuximab and the TLR2 ligand Pam3CSK4 showed increased infiltration of immune cells into the tumors compared to mice that received cetuximab monotherapy, resulting in a significant delay in tumor growth or even complete tumor regression. Moreover, combination treatment resulted in improved overall survival in vivo. In conclusion, combining tumor-targeting antibody-based immunotherapy with TLR stimulation represents a promising treatment strategy to improve the clinical outcomes of cancer patients. This treatment could well be applied together with other therapeutic strategies such as anti-PD-(L)1 checkpoint inhibition to further overcome immunosuppression.

Highlights

Head and neck squamous cell carcinoma (HNSCC) is an aggressive type of cancer that arises in the mucosal linings covering the upper aerodigestive tract, including the oral cavity, oropharynx, hypopharynx and larynx
To investigate the cetuximab-mediated elimination of HNSCC cells, ADCC experiments were performed with ten different HNSCC cell lines as target cells and healthy donor peripheral blood mononuclear cells (PBMCs) as effector cells (Figure 1A)
As TLR1/2, TLR2/6, TLR4 and TLR5 are the most prominently expressed surface Toll-like receptor (TLR) on Natural killer (NK) cells [28], we investigated whether the co-activation of FcγRs with these TLRs would enhance the cytotoxic activity of NK cells, resulting in improved tumor cell killing

Summary

Introduction

Head and neck squamous cell carcinoma (HNSCC) is an aggressive type of cancer that arises in the mucosal linings covering the upper aerodigestive tract, including the oral cavity, oropharynx, hypopharynx and larynx. The tumor microenvironment (TME) in HNSCC comprises stromal cells, including endothelial cells and cancer-associated fibroblasts (CAFs). Both tumor cells themselves and CAFs secrete a wide variety of factors that induce immune cell recruitment to the TME. The majority of tumor-infiltrating cells have an immunosuppressive phenotype, such as regulatory T-lymphocytes, myeloid-derived suppressor cells (MDSCs) and tumor-associated macrophages (TAMs) [2,3,4,5]. The presence of these cells is associated with poor prognosis [4]

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