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Abstract 2108: ScRNA-Seq and imaging mass cytometry analyses unveil iNKT cells-mediated anti-tumor immunity in pancreatic tumor liver metastasis


 Background: Liver metastasis is a common feature of pancreatic tumor and associated with a poor outcome. Invariant natural killer cells (iNKT) are innate-like T cells that are important regulators of innate and adaptive immune responses in cancer and is the largest subset of lymphocytes within liver. However, the role of iNKT cells in pancreatic tumor liver metastasis (PTLM) is still not clear. Hypothesis: activated liver iNKT cells could play a role in PTLM.
 Method: We established a PTLM mouse model by hemi-spleen murine pancreatic tumor cells (CF1242) injection. We combined single-cell RNA sequencing, flow cytometry analysis, and imaging mass cytometry analysis to landscape the immune profile of tumor microenvironment during PTLM with or without iNKT cell activator α-galactosylceramide (αGC) treatment.
 Results: αGC treatment significantly blocked PTLM development based on liver weight compared to control group(P<0.001). We sequenced total 6,728 CD45+ infiltrating immune cells in PTLM with/without αGC treatment and identified total 12 immune subpopulations that were present in both samples at different frequencies. Post αGC treatment, activated iNKT cells in liver appeared robust population expansion and enriched in cytotoxic signaling pathway. Alternatively, activated iNKT cells promoted infiltrating CD4 T cells to a Th1 profile shift, and promoted infiltrating CD8 T cells toward an effector/memory phenotype (upregulation of the CD44, T-bet, and IFN-γ; P<0.001), and increased NK cell cytotoxic activity (P<0.001). In addition, we observed that aGC treatment blocked infiltrating CD8 T cell exhaustion by downregulating the immune checkpoint TIGIT, Lag3, and PD-1 (P<0.001). Analysis of tumor-infiltrating myeloid clusters revealed that macrophage skewed to M1 phenotype compared to the control group(P<0.05).
 Conclusion: αGC treatment can expand and activate liver iNKT cells, which may directly increase tumor cell killing ability, recruit immune cells to tumor sites, and orchestrate the anti-tumor function through boost both innate and adaptive tumor immunity to inhibit PTLM. Our results indicate that iNKT cells may serve as a new immunotherapeutic target for PTLM. (Funded by HFCI and NIH/NIAID)
 Citation Format: Jie Wang, Qijun Yi, Tingting Liu, Yi Yao, Ian Loveless, Kalpana Subedi, Indra Adrianto, Howard Crawford, Li Zhou, Qing-Sheng Mi. ScRNA-Seq and imaging mass cytometry analyses unveil iNKT cells-mediated anti-tumor immunity in pancreatic tumor liver metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2108.