Abstract 5864: Preclinical investigation of anti-tumor efficacy of allogeneic natural killer cells combined with cetuximab for head and neck squamous cell carcinoma

Abstract Background: Head and neck squamous cell carcinoma (HNSCC) is a challenging malignancy with limited response rates to conventional therapies, including immune checkpoint inhibitors and cetuximab monotherapy. Despite recent advancements in immunotherapy, a significant unmet need remains owing to suboptimal efficacy. This study investigated the potential of a novel combination therapy using allogeneic natural killer (NK) cells and cetuximab, an anti-epidermal growth factor receptor monoclonal antibody, to enhance anti-tumor efficacy in HNSCC. Method: Allogeneic NK cells from healthy donors were expanded and tested in vitro, and NOG (NOD/Shi-scid/IL-2Rγ null) xenograft mouse models were used to evaluate their efficacy and functionality. In vitro assays were employed to evaluate cytotoxicity against HNSCC cells (FaDu) in combination with cetuximab, focusing on the effects of antibody-dependent cellular cytotoxicity (ADCC). In vivo experiments assessed the efficacy of high-dose NK cell infusion with cetuximab in reducing tumor growth and improving survival in xenograft mouse models. NK cell infiltration and cytotoxicity were analyzed using flow cytometry and immunohistochemistry. Results: An increased dose of NK cells was selected for subsequent studies owing to its superior ability to improve survival outcomes and inhibit tumor cell proliferation despite no marked differences growth between the NK-low and NK-high groups. During the selection process for allogeneic NK cells and their partner drugs, interleukin (IL)-2 was selected and tested in the xenograft mouse model. However, the lack of an improved anti-tumor response through the IL-2 combination in vivo prompted us to investigate other combination treatment partners. While IL-2 showed limitations in enhancing NK cell activity in vivo, Combination therapy encompassing allogeneic NK cells and cetuximab demonstrated significantly enhanced cytotoxicity against FaDu cells in vitro, which was attributed to ADCC. In vivo, the combination of allogeneic NK cells and cetuximab effectively managed HNSCC in NOG xenograft mouse model, showing significant reductions in tumor growth and improved survival rates. Additionally, Flow cytometry and immunohistochemistry revealed increased infiltration of NK cells within the tumors, confirming enhanced ADCC-mediated anti-tumor activity. These results highlight the potential of this combination therapy to enhance anti-tumor efficacy. Conclusion: These findings underscore the potential of combining allogeneic NK cells with cetuximab to improve the therapeutic outcomes in HNSCC. The observed synergy between NK cells and cetuximab highlights a promising therapeutic approach for enhancing NK cell-mediated cytotoxicity through ADCC and, lays a foundation for future clinical trials aimed at addressing unmet needs in HNSCC treatment. Citation Format: Chaeyeon Kim, Mina Han, Gamin Kim, Wonrak Son, Jeongah Kim, Minchan Gil, Yong-Hee Rhee, Nam Suk Sim, Chang Gon Kim, Hye Ryun Kim. Preclinical investigation of anti-tumor efficacy of allogeneic natural killer cells combined with cetuximab for head and neck squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 5864.