Regulatory T cells and skin tumors.

Regulatory T cells (Tregs) are essential for maintaining self-tolerance and also play a pivotal role in diminishing anti-tumor immunoresponse. The frequency and activity of CD4(+)CD25(+)FoxP3(+) Tregs in the circulation and tumor microenvironment is increased in patients with various cancers. Although, the exact role of Tregs in cutaneous tumors remains unclear, Tregs contribute to tumor progression of skin cancers, explaining, in part, why immunotherapy with dendritic cell-based vaccination for melanoma patients has not been satisfactory. Therefore, there has been considerable interest in determining their function in order to treat skin cancers such as malignant melanoma. However, clinical trials with specific antibodies designed to overcome Treg-associated immunosuppression resulted in limited clinical efficacy with some adverse effects. A better understanding of the role of Tregs in the tumor environment might contribute to the development of novel approaches for treating various cutaneous tumors. In this review, we focus on clinical and basic research on Tregs in relation to skin tumors and describe some important patents for the treatment of skin cancers.