Characterization of CD103+ CD8+ tissue-resident T cells in esophageal squamous cell carcinoma: may be tumor reactive and resurrected by anti-PD-1 blockade.

Though therapy that promotes anti-tumor response about CD8+ tumor-infiltrating lymphocytes (TILs) has shown great potential, clinical responses to CD8+ TILs immunotherapy vary considerably, largely because of different subpopulation of CD8+ TILs exhibiting different biological characters. To define the relationship between subpopulation of CD8+ TILs and the outcome of antitumor reaction, the phenotype and function of CD103+ CD8+ TILs in esophageal squamous cell carcinoma (ESCC) were investigated. CD103+ CD8+ TILs were presented in ESCC, which displayed phenotype of tissue-resident memory T cells and exhibited high expression of immune checkpoints (PD-1, TIM-3). CD103+ CD8+ TILs were positively associated with the overall survivals of ESCC patients. This population of cells elicited potent proliferation and cytotoxic cytokine secretion potential. In addition, CD103+ CD8+ TILs were elicited potent anti-tumor immunity after anti-PD-1 blockade and were not affected by chemotherapy. This study emphasized the feature of CD103+ CD8+ TILs in immune response and identified potentially new targets in ESCC patients.