CXCR6 and cancer: Among these tumor‐reactive CD8+ cytotoxic effector T cells, trTeff‐CXCR6 is the only PDCD1+/ENTPD1+/ITGAE+ population that contains globally‐expanded clones (Figure S13C, Supporting Information) and might support strong antitumor activity in both primary and metastatic tumor sites.[28] In concordance with reports in other cancer types,[28, 29] trTeff‐CXCR6 gene expression signature is associated with favorable clinical outcomes (Figure S13J, Supporting Information).