The Role of Regulatory T Cells in Mesothelioma.

Malignant mesothelioma (MM) appears to be responsive to immunotherapy. The lack of complete tumour cure as a result of many immunotherapies tested to date suggests that the immune response to MM is complex and multi-parametric. Regulatory T (Treg) cells are prevalent within murine and human mesotheliomas with their removal shown to result in tumour growth inhibition and the release of anti-tumour effector T cells from immunosuppression. The targeting of immune checkpoints as treatments for various solid tumours has recently shown promise in clinical settings. In addition, synergy between chemotherapy and immunotherapy has been demonstrated for many cancers, including mesothelioma. Here we demonstrate Treg cells as critical mediators of the anti-tumour immune response to MM and potential targets for anti-tumour immunotherapy; though the timing and dosage of Treg cell manipulating immunotherapies need to be optimised.