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Purpose: Natural killer (NK)-cell-based immunotherapy may overcome obstacles to effective T-cell-based immunotherapy such as the presence of genomic alterations in IFN response genes and antigen presentation machinery. All immunotherapy approaches may be abrogated by the presence of an immunosuppressive tumor microenvironment present in many solid tumor types, including head and neck squamous cell carcinoma (HNSCC). Here, we studied the role of myeloid-derived suppressor cells (MDSC) in suppressing NK-cell function in HNSCC.Experimental Design: The ability of peripheral and tumorinfiltrating MDSC from mice bearing murine oral cancer 2 (MOC2) non-T-cell-inflamed tumors and from patients with HNSCC to suppress NK-cell function was studied with real-time impedance and ELISpot assays. The therapeutic efficacy of SX-682, a smallmolecule inhibitor of CXCR1 and CXCR2, was assessed in combination with adoptively transferred NK cells.Results: Mice bearing MOC2 tumors pathologically accumulate peripheral CXCR2 þ neutrophilic-MDSC (PMN-MDSC) that traffic into tumors and suppress NK-cell function through TGFb and production of H 2 O 2 . Inhibition of MDSC trafficking with orally bioavailable SX-682 significantly abrogated tumor MDSC accumulation and enhanced the tumor infiltration, activation, and therapeutic efficacy of adoptively transferred murine NK cells. Patients with HNSCC harbor significant levels of circulating and tumor-infiltrating CXCR1/2 þ CD15 þ PMN-MDSC and CD14 þ monocytic-MDSC. Tumor MDSC exhibited greater immunosuppression than those in circulation. HNSCC tumor MDSC immunosuppression was mediated by multiple, independent, cell-specific mechanisms including TGFb and nitric oxide.Conclusions: The clinical study of CXCR1/2 inhibitors in combination with adoptively transferred NK cells is warranted.

Purpose: Surgical resection of primary tumor with regional lymphadenectomy remains the treatment of choice for patients with advanced human papillomavirus-negative head and neck squamous cell carcinoma. However, even when pathologic disease-free margins can be achieved, locoregional and/or distant disease relapse remains high. Perioperative immunotherapy may improve outcomes, but mechanistic data supporting the use of neoadjuvant or adjuvant treatment clinically are sparse.Experimental Design: Two syngeneic models of oral cavity carcinoma with defined T-cell antigens were treated with programmed death receptor 1 (PD-1) mAb before or after surgical resection of primary tumors, and antigen-specific T-cell responses were explored with functional and in vivo challenge assays.Results: We demonstrated that functional immunodominance developed among T cells targeting multiple independent tumor antigens. T cells specific for subdominant antigens expressed greater levels of PD-1. Neoadjuvant, but not adjuvant, PD-1 immune checkpoint blockade broke immunodominance and induced Tcell responses to dominant and subdominant antigens. Using tumors lacking the immunodominant antigen as a model of antigen escape, neoadjuvant PD-1 immune checkpoint blockade induced effector T-cell immunity against tumor cells lacking immunodominant but retaining subdominant antigen. When combined with complete surgical excision, neoadjuvant PD-1 immune checkpoint blockade led to formation of immunologic memory capable of preventing engraftment of tumors lacking the immunodominant but retaining subdominant antigen.Conclusions: Together, these results implicate PD-1 expression by T cells in the mechanism of functional immunodominance among independent T-cell clones within a progressing tumor and support the use of neoadjuvant PD-1 immune checkpoint blockade in patients with surgically resectable carcinomas.

Failed T cell-based immunotherapies in the presence of genomic alterations in antigen presentations pathways may be overcome by NK cell-based immunotherapy. This approach may still be limited by the presence of immunosuppressive myeloid populations. Here, we demonstrate that NK cells (haNKs) engineered to express a PD-L1 chimeric antigen receptor (CAR) haNKs killed a panel of human and murine head and neck cancer cells at low effector-to-target ratios in a PD-L1-dependent fashion. Treatment of syngeneic tumors resulted in CD8 and PD-L1-dependent tumor rejection or growth inhibition and a reduction in myeloid cells endogenously expressing high levels of PD-L1. Treatment of xenograft tumors resulted in PD-L1-dependent tumor growth inhibition. PD-L1 CAR haNKs reduced levels of macrophages and other myeloid cells endogenously expressing high PD-L1 in peripheral blood from patients with head and neck cancer. The clinical study of PD-L1 CAR haNKs is warranted.

Although the adaptive immune system can detect and eliminate malignant cells, patients with intact and fully functional immune systems develop head and neck cancer. How is this paradox explained? Manuscripts published in the English language from 1975 to 2018 were reviewed using search inputs related to tumor cell antigenicity and immunogenicity, immunodominance, cancer immunoediting and genomic alterations present within carcinomas. Early in tumor development, T cell responses to immunodominant antigens may lead to the elimination of cancer cells expressing these antigens and a tumor composed to tumor cells expressing only immunorecessive antigens. Conversely, other tumor cells may acquire genomic or epigenetic alterations that result in an antigen processing or presentation defect or other inability to be detected or killed by T cells. Such T cell insensitive tumor cells may also be selected for in a progressing tumor. Tumors harboring subpopulations of cells that cannot be eliminated by T cells may require non-T cell-based treatments, such as NK cell immunotherapies. Recognition of such tumor cell populations within a heterogeneous cancer may inform the selection of treatment for HNSCC in the future.

27Failed T cell-based immunotherapies in the presence of genomic alterations in antigen presentations 28 pathways may be overcome by NK cell-based immunotherapy. This approach may still be limited by the 29 presence of immunosuppressive myeloid populations. Here we demonstrate that NK cells (haNKs) 30 engineered to express a PD-L1 chimeric antigen receptor (CAR) haNKs killed a panel of human and 31 murine head and neck cancer cells at low effector-to-target ratios in a PD-L1-dependent fashion. 32 Treatment of syngeneic tumors resulted in CD8 and PD-L1-dependent tumor rejection or growth 33 inhibition and a reduction in myeloid cells endogenously expressing high levels of PD-L1. Treatment of 34 xenograft tumors resulted in PD-L1 dependent tumor growth inhibition. PD-L1 CAR haNKs reduced 35 levels of macrophages and other myeloid cells endogenously expressing high PD-L1 in peripheral blood 36 from patients with head and neck cancer. The clinical study of PD-L1 CAR haNKs is warranted. 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 3 Background 53 T cell-based immunotherapy, such as immune checkpoint blockade or adoptive T cell transfer, is 54 limited by the ability of T cells to detect major histocompatibility complex (MHC)-presented antigen by 55 tumor cells. Through selective immune pressure during tumorigenesis and progression and genomic 56 instability, subpopulations of tumor cells acquire mutations that lead to defective type II interferon (IFN) 57 responses and altered antigen processing and presentation (1, 2). The presence of these mutations predicts 58 failure to respond to immune checkpoint blockade and adoptive T cell transfer immunotherapy(3-6). 59Natural killer (NK) cell-based immunotherapy may overcome genetic mechanisms of resistance 60 to T cell-based immunotherapy through antigen-and MHC-independent recognition of malignant cells. 61NK cells express germ-line receptors that are either stimulatory or inhibitory, and the summation of these 62 signals determines activation status (7). NK-92 cells, derived from a Non-Hodgkin's lymphoma patient, 63 can be continuously expanded in culture and following irradiation, can be safely administered in high 64 doses to patients with cancer(8-10). High-affinity NK (haNK) cells are NK-92 cells engineered to express 65 endoplasmic reticulum-retained IL-2(11), have demonstrated potent effector function in numerous pre-66 clinical models(12, 13), and following irradiation, can also be safely administered in high doses to 67 patients(14). haNKs represent an "off the shelf" NK cellular therapy available for pre-clinical and clinical 68 study. However, barriers within the tumor microenvironment that further limit T cell activation and 69 function such as the presence of immunosuppressive myeloid cells also can limit the activation and 70 function of NK cells (15, 16). Thus, addressing the presence of immunosuppressive myeloid cell 71 populations in the periphery and tumor microenvironment of patients with cancer is likely to be required 72 for effective NK cell-bas...

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<div>AbstractPurpose:<p>Natural killer (NK)-cell–based immunotherapy may overcome obstacles to effective T-cell–based immunotherapy such as the presence of genomic alterations in IFN response genes and antigen presentation machinery. All immunotherapy approaches may be abrogated by the presence of an immunosuppressive tumor microenvironment present in many solid tumor types, including head and neck squamous cell carcinoma (HNSCC). Here, we studied the role of myeloid-derived suppressor cells (MDSC) in suppressing NK-cell function in HNSCC.</p>Experimental Design:<p>The ability of peripheral and tumor-infiltrating MDSC from mice bearing murine oral cancer 2 (MOC2) non-T-cell–inflamed tumors and from patients with HNSCC to suppress NK-cell function was studied with real-time impedance and ELISpot assays. The therapeutic efficacy of SX-682, a small-molecule inhibitor of CXCR1 and CXCR2, was assessed in combination with adoptively transferred NK cells.</p>Results:<p>Mice bearing MOC2 tumors pathologically accumulate peripheral CXCR2⁺ neutrophilic-MDSC (PMN-MDSC) that traffic into tumors and suppress NK-cell function through TGFβ and production of H₂O₂. Inhibition of MDSC trafficking with orally bioavailable SX-682 significantly abrogated tumor MDSC accumulation and enhanced the tumor infiltration, activation, and therapeutic efficacy of adoptively transferred murine NK cells. Patients with HNSCC harbor significant levels of circulating and tumor-infiltrating CXCR1/2⁺ CD15⁺ PMN-MDSC and CD14⁺ monocytic-MDSC. Tumor MDSC exhibited greater immunosuppression than those in circulation. HNSCC tumor MDSC immunosuppression was mediated by multiple, independent, cell-specific mechanisms including TGFβ and nitric oxide.</p>Conclusions:<p>The clinical study of CXCR1/2 inhibitors in combination with adoptively transferred NK cells is warranted.</p></div>