Tumor-draining lymph nodes are promising resources for adoptive cell therapy in colorectal cancers

Background: Although adoptive cell therapy (ACT), such as tumor-infiltrating lymphocyte (TIL) therapy, has demonstrated encouraging potential against solid cancers, exhaustion and the low presence of TILs limit its sustainable anti-tumor activity. Tumor-draining lymph nodes (TDLNs) are primary sites, where anti-tumor lymphocytes are primed to tumor-specific antigens. However, immune activity of T cells in TDLNs toward cancer cells has not been comprehensively analyzed.Methods: We freshly collected T cells from a primary tumor and their TDLNs from four CRC surgical specimens and compared their phenotypes using single-cell RNA/T cell receptor (TCR) sequencing.Results: TCR clonotypes of PD-1-expressing CD8+ T cells in TDLNs were found to be commonly shared with those of TILs in primary tumors. Tumor-reactive T cells with TCR clonotypes in common with TILs could be induced from non-metastatic TDLNs when they were co-cultured with autologous tumor cells. The majority of tumor-reactive CD8+ T cells in TDLNs showed a memory or early activating phenotype, while TILs showed an exhausted phenotype. Expression profiles were significantly different between tumor-reactive and non-reactive CD8+ T cells in TDLNs.Conclusion: Tumor-reactive effector T cells were present in non-metastatic TDLNs and could be expanded in vitro in the presence of autologous tumor cells. TDLNs could be harnessed as an alternative cell source for ACT.