Combination of Expanded Allogeneic NK Cells and T Cell-Based Immunotherapy Exert Enhanced Antitumor Effects

SIMPLE SUMMARY: The clinical efficacy of neoantigen-reactive tumor-infiltrating lymphocytes and T cell receptor-engineered T cells (TCR-T) therapy is primarily attributed to the effective CD8(+) T cell responses that are limited to HLA-I presenting tumor-specific antigens. NK cells have the therapeutic potential for refractory tumors that develop immune evasion due to HLA-I downregulation. In this study, we compare different culture systems and solve the challenge of the large-scale expansion of NK cells with strong cytotoxic activity. We attempt to seek the transcriptional alteration of NK cells expanded by different culture conditions and identify the genomic profiles of optimized NK cells with strong cytotoxicity. Here, we demonstrate that the cooperation of “off-the-shelf” NK cells with tumor-activated alloreactive T cells or with NY-ESO-1-specific 1G4 TCR-T cells further enhanced tumors lysis, especially against tumors with HLA-I downregulation. Our study improves the immune incompetence caused by HLA-I downregulation and innovates future combination strategies for cancer immunotherapies. ABSTRACT: Immunotherapies based on immune checkpoint blockade, neoantigen-reactive tumor-infiltrating lymphocytes and T cell receptor-engineered T cells (TCR-T) have achieved favorable clinical outcomes in tumor treatment. However, sustained immune response and tumor regression have been observed only in a few patients due to immune escape. Natural killer (NK) cells can mediate direct tumor lysis and target cancer cells with low or no expression of human leukocyte antigen class I (HLA-I) that are no longer recognized by T cells during immune escape. Therefore, the combination of T cell-based immunotherapy and NK cell therapy is a promising strategy for improving antitumor response and response rate. However, allogeneic NK cells for adoptive cell therapy have been limited by both the required cell number and quality. Here, we developed an efficient manufacturing system that relies on genetically modified K562 cells for the expansion of high-quality NK cells derived from peripheral blood mononuclear cells. NK cells with the optimal expansion and activity were identified by comparing the different culture systems. Furthermore, we demonstrated that the cooperation of NK cells with tumor-reactive T cells or with NY-ESO-1-specific TCR-T cells further enhanced tumors lysis, especially against tumors with downregulated HLA-I expression. The advantages of HLA-mismatch and non-rejection by other allogeneic immune cells demonstrated the potential of “off-the-shelf” NK cells with the capacity to target tumors for immunotherapy. Our results indicate that the combination strategy based on T cell and allogeneic NK cell immunotherapy might have potential for overcoming the barrier of immune incompetence caused by HLA-I downregulation.