A role for T-bet-mediated tumour immune surveillance in anti-IL-17A treatment of lung cancer

Lung cancer is the leading cause of cancer deaths worldwide. The cytokine interleukin-17A supports tumour vascularization and growth, however, its role in lung cancer is unknown. Here we show, in the lungs of patients with lung adenocarcinoma, an increase in interleukin-17A that is inversely correlated with the expression of T-bet and correlated with the T regulatory cell transcription factor Foxp3. Local targeting of interleukin-17A in experimental lung adenocarcinoma results in a reduction in tumour load, local expansion of interferon-γ-producing CD4 + T cells and a reduction in lung CD4 + CD25 + Foxp3 + regulatory T cells. T-bet (−/−) mice have a significantly higher tumour load compared with wild-type mice. This is associated with the local upregulation of interleukin-23 and induction of interleukin-17A/interleukin-17R-expressing T cells infiltrating the tumour. Local anti-interleukin-17A antibody treatment partially improves the survival of T-bet (−/−) mice. These results suggest that local anti-interleukin-17A antibody therapy could be considered for the treatment of lung tumours. The tumour microenvironment is often found to be immunosuppressive. Reppert and colleagues show that human and murine lung tumours harbour IL-17A-producing T cells, and that blocking IL-17A increases survival in mice, suggesting that anti-IL-17A therapy may be useful in treating lung cancer.