CD8⁺CD103⁺ tumor-infiltrating lymphocytes are tumor-specific tissue-resident memory T cells and a prognostic factor for survival in lung cancer patients

We had previously demonstrated the role of CD103 integrin on lung tumor-infiltrating lymphocyte (TIL) clones in promoting specific TCR-mediated epithelial tumor cell cytotoxicity. However, the contribution of CD103 on intratumoral T cell distribution and functions and the prognosis significance of TIL subpopulations in non-small cell lung carcinoma (NSCLC) have thus far not been systematically addressed. In this study, we show that an enhanced CD103⁺ TIL subset correlates with improved early stage NSCLC patient survival and increased intraepithelial lymphocyte infiltration. Moreover, our results indicate that CD8⁺CD103⁺ TIL, freshly isolated from NSCLC specimens, display transcriptomic and phenotypic signatures characteristic of tissue-resident memory T cells and frequently express PD-1 and Tim-3 checkpoint receptors. This TIL subset also displays increased activation-induced cell death and mediates specific cytolytic activity toward autologous tumor cells upon blockade of the PD-1-PD-L1 interaction. These findings emphasize the role of CD8⁺CD103⁺ tissue-resident memory T cells in promoting intratumoral CTL responses and support the rationale for using anti-PD-1 blocking Ab to reverse tumor-induced T cell exhaustion in NSCLC patients.