9P - CXCR6+PD-1- Tissue Resident memory T cells are associated with poor prognosis in patients with metastatic colorectal cancer

Background

Tissue-resident memory (T_RM) T cells have emerged as key players in cancer immunosurveillance, and their presence has been linked to a favorable clinical outcome in solid cancer patients. Liver metastases exhibit a highly immunosuppressive tumor microenvironment, however, the role and clinical impact of T_RM cells infiltration in colorectal cancer remains elusive.

Methods

An exhaustive profiling was conducted on tumor-infiltrating lymphocytes isolated from 27 patients’ colorectal cancer (CRC) liver metastases. Cytokine production was evaluated in in vitro-activated T_RM and non-T_RM cells. 3D spheroid models were also used to study CXCR6^+/- T_RM cells cytotoxicity. Prognostic value of T_RM cells was assessed. Single-cell RNAseq data were analyzed to investigate the transcriptomic profile of T_RM cells subsets.

Results

Our analyses showed that only infiltration with CD103⁺CD69⁺ T_RM cells was predictive of recurrence-free survival (RFS). However, CXCR6 expression on this T_RM subset helped to stratify this population’s prognostic impact and was associated with shorter RFS. CXCR6 expression was inversely correlated to PD-1, HLA-DR, and CD39 expression, three well-validated biomarkers of tumor-reactive T cells. Strikingly, the expression of PD-1 in this T_RM population was associated with improved patients’ prognosis. Interestingly, both in vitro and single-cell RNAseq data analyses revealed that CXCR6^-PD1⁺ T_RM cells showed significantly lower levels of TIM3 and LAG3 expression compared to CXCR6⁺PD1^- that could be explained by a non-terminal exhausted state. Although both T_RM populations presented high production levels of IFNg, GZMB, and IL-2; CXCR6^-PD1⁺ T_RM cells produced higher levels of TNFa. We next assessed TCF1 and TOX expression. Interestingly, CXCR6⁺PD1^- T_RM cells were more TCF1^-TOX⁺, contrarily to CXCR6^-PD1⁺ T_RM cells that were more stem-like ‘TCF1^-TOX^+’. Finally, CXCR6^-PD1⁺ T_RM cells showed a significant increase in Ki67 expression.

Conclusions

We identified a novel population of T_RM cells CXCR6^-PD1⁺ that exhibit a ‘stem-like’ phenotype with higher proliferation capacity and are associated with improved prognosis in metastatic CRC patients.

Legal entity responsible for the study

UMR RIGHT 1098.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.