SUMMARY While current immune checkpoint therapy (ICT) mainly targets lymphoid cells, it is associated with a broader remodeling of the tumor micro-environment. Here, using complementary forms of high dimensional profiling, we define differences across all hematopoietic cells from syngeneic mouse tumors during unrestrained tumor growth or effective ICT. Unbiased assessment of gene expression of tumor infiltrating cells by single cell RNA sequencing (scRNAseq) and longitudinal assessment of cellular protein expression by mass cytometry (CyTOF) revealed significant remodeling of both the lymphoid and myeloid intratumoral compartments. Surprisingly, we observed multiple subpopulations of monocytes/macrophages, distinguishable by the markers CD206, CX3CR1, CD1d and iNOS, that change over time during ICT in a manner partially dependent on IFNγ. Our data support the hypothesis that this macrophage polarization/activation results from effects on circulatory monocytes and early macrophages entering tumors, rather than on pre-polarized mature intratumoral macrophages.

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NK cells are a promising cellular immunotherapy for cancer. Cytokine-induced memory-like (ML) NK cells differentiate after activation with IL-12, IL-15, and IL-18, exhibit potent anti-tumor responses, and safely induce complete remissions in patients with leukemia. However, many cancers are not fully recognized via NK cell receptors. Chimeric antigen receptors (CAR) have been utilized to enhance tumor-specific recognition by effector lymphocytes. We hypothesized that memory-like differentiation and CAR-engineering would result in complementary improvements in NK cell responses against NK-resistant cancers. To test this idea, peripheral blood ML NK cells were modified to express an anti-CD19 CAR (19-CAR-ML), which displayed significantly increased IFN-γ production, degranulation, and specific killing against NK-resistant lymphoma lines and primary targets, compared to non-specific control CAR-ML NK cells or conventional CAR NK cells. The 19-CAR and ML responses were synergistic, CAR-specific, and required ITAM signaling. Furthermore, 19-CAR-ML NK generated from lymphoma patients exhibited improved responses against their autologous lymphoma. 19-CAR-ML NK cells controlled lymphoma burden in vivo and improved survival in human xenograft models. Thus, CAR engineering of ML NK cells enhanced responses against resistant cancers and warrant further investigation, with the potential to broaden ML NK cell recognition against a variety of NK cell-resistant tumors.

Natural killer (NK) cells are an emerging cancer cellular therapy and potent mediators of antitumor immunity. Cytokine-induced memory-like (ML) NK cellular therapy is safe and induces remissions in patients with acute myeloid leukemia (AML). However, the dynamic changes in phenotype that occur after NK-cell transfer that affect patient outcomes remain unclear. Here, we report comprehensive multidimensional correlates from ML NK cell–treated patients with AML using mass cytometry. These data identify a unique in vivo differentiated ML NK–cell phenotype distinct from conventional NK cells. Moreover, the inhibitory receptor NKG2A is a dominant, transcriptionally induced checkpoint important for ML, but not conventional NK-cell responses to cancer. The frequency of CD8α+ donor NK cells is negatively associated with AML patient outcomes after ML NK therapy. Thus, elucidating the multidimensional dynamics of donor ML NK cells in vivo revealed critical factors important for clinical response, and new avenues to enhance NK-cell therapeutics. Significance: Mass cytometry reveals an in vivo memory-like NK-cell phenotype, where NKG2A is a dominant checkpoint, and CD8α is associated with treatment failure after ML NK–cell therapy. These findings identify multiple avenues for optimizing ML NK–cell immunotherapy for cancer and define mechanisms important for ML NK–cell function. This article is highlighted in the In This Issue feature, p. 1775

Highlights d Induced Eomes deletion results in a rapid decrease in NK cell numbers d Eomes-deleted stage III NK cells exhibit increased apoptosis d Eomes-deleted stage II and III NK cells exhibit differentiation defects d Induced Eomes deletion compromises NK cytotoxicity and MHCI À/À rejection in vivo