Abstract 5519: Enlarged metastasis-free tumor-draining lymph node is a marker of tumor invasion in local tissues with an active NK cell-mediated immunity
Authors: Wan Zixiao , Yu Huichuan 
Published: March 2024

Abstract
Background: Colorectal cancer (CRC) is the third most common cancer worldwide, accounting for about 10% of all new cancer cases. The tumor-draining lymph node (TDLN) is a key site for the development of anti-tumor immunity that has been reported to be involved in both CD8+ T and NK cells. As a major role of innate immunity, NK cells can produce IFN-γ, perforin and granzyme to eliminate tumor cells in the early stages of cancer development. This study aimed to investigate the difference of clinicopathological and immunological profiles in local tissues between CRC patients with enlarged and non-enlarged metastasis-free TDLNs.
Methods: The patient cohort was obtained from the NEPDC cohort (No. 2015CB554000). A total of 45 patients with pathologically confirmed stage I-II colorectal cancer were included in this study. Based on the MRI, these patients were divided into enlarged and non-enlarged TDLN groups (lymph nodes &gt;/= 5mm and lymph nodes &lt; 5mm). We collected the tumor tissue and tumor-adjacent normal tissue that was 2 cm away from the tumor lesion. The genomic DNA of the tumor and tumor-adjacent normal tissues was treated with bisulfite and analyzed with the EPIC methylation array. The MeTMEC algorithm based on the methylation profile estimated subsequent cell abundance in these patient tissues.
Results: The study sample was comprised of 22 enlarged TDLN and 23 non-enlarged TDLN patients. There were 4 T1-T2 and 18 T3-T4 patients in the enlarged TDLN group, with 12 T1-T2 and 11 T3-T4 patients in the non-enlarged TDLN group. The proportion of T3-T4 patients in the enlarged TDLN group was higher than that in the non-enlarged TDLN group (p=0.017, Chi-squared test), suggesting an advanced invasion in the local tissue of patients with enlarged TDLN. Then, the abundance of monocytes, dendritic cells, macrophages, neutrophils, eosinophils, Treg cells, naive T cells, memory T cells, CD8+ T cells, NK cells, and B cells in the tumor and tumor-adjacent normal tissues were inferred with the MeTMEC algorithm by using DNA methylation profile. In the T1-T2 subset, we found that the infiltration of NK cells in the tumor-adjacent normal tissues was significantly more abundant in the enlarged TDLN group compared with the non-enlarged TDLN group (p=0.021, t-test), suggesting an active immune response of NK cells for potential local tumor control. No significant difference in other immune cells was observed between the two groups.
Conclusion: Enlarged TDLN indicates an advanced invasion of tumors in local tissues with an active NK cell-mediated immunity. Our findings suggest that enlarged metastasis-free TDLN might be a promising marker for NK cell-based cancer immunotherapy.
Key words: Colorectal Cancer, Lymph Nodes, Natural Killer Cells
Citation Format: Zixiao Wan, Huichuan Yu. Enlarged metastasis-free tumor-draining lymph node is a marker of tumor invasion in local tissues with an active NK cell-mediated immunity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5519.