CD103-Positive Tumor-Infiltrating Lymphocytes Predict a Favorable Prognosis in Colorectal Cancer with Liver Metastasis.

[BACKGROUND] High infiltration of CD103 tumor infiltrating lymphocytes (TILs) is associated with improved patient survival in colorectal cancer. However, the spatial distribution and clinical significance of CD103 TILs in colorectal liver metastasis (CRLM) remain unclear.

[METHODS] This study enrolled 84 patients with CRLM who underwent simultaneous surgical resection of both primary colorectal tumors (PT) and liver metastases (LM). The abundance of CD103 TILs in different intratumoral compartments were evaluated using immunohistochemistry. Additionally, multiplex immunofluorescence analysis was performed to assess CD103 TIL subsets. Single-cell RNA sequencing (scRNA-seq) and spatial transcriptomic analysis were performed to investigate the functional differences of CD103CD8 T cells between PT and LM using a published dataset.

[RESULTS] The presence of CD103 TILs in PT did not correlate with the prognosis of patients with CRLM. Conversely, an increased infiltration of CD103 TILs in LM was associated with improved survival outcomes. Notably, CD103 TILs in the stromal compartments of the tumor center of LM emerged as an independent prognostic factor for CRLM patients. The majority of CD103 TILs in CRLM tissues were identified as CD8CD103 cells, followed by CD4CD103 cells. scRNA-seq analysis showed that the CD103CD8 T cells in the PT exhibit characteristics typical of CD8 cytotoxic T cells, while those in the LM display features of tissue-resident memory T cells.

[CONCLUSIONS] These findings reveal the heterogeneity in the spatial distribution of CD103 TILs within both PT and LM tissues. Notably, the infiltration of CD103 TILs in LM serves as a prognostic biomarker for CRLM patients.