The Multifaceted Role of Regulatory T Cells in Breast Cancer.

The microenvironment of breast cancer hosts a dynamic cross talk between diverse players of the immune system. While cytotoxic immune cells are equipped to control tumor growth and metastasis, tumor-corrupted immunosuppressive immune cells strive to impair effective immunity and promote tumor progression. Of these, regulatory T cells (T _regs ), the gatekeepers of immune homeostasis, emerge as multifaceted players involved in breast cancer. Intriguingly, clinical observations suggest that blood and intratumoral T _regs can have strong prognostic value, dictated by breast cancer subtype. Accordingly, emerging preclinical evidence shows that T _regs occupy a central role in breast cancer initiation and progression and provide critical support to metastasis formation. Here, T _regs are not only important for immune escape but also promote tumor progression independent of their immune regulatory capacity. Combining insights into T _reg biology with advances made across the rapidly growing field of immuno-oncology is expected to set the stage for the design of more effective immunotherapy strategies.
Competing Interests: Disclosure Statement K.E.d.V. reports research funding from Roche and is a consultant for Third Rock Ventures, both of which are outside the scope of this work. K.K. reports no competing interests.