| The immunosuppressive features of tumor lesions participate not only as one of the
major players inducing cancer progression but also a big challenge for effective
immunotherapy. It has been found that immunosuppression associated with chronic
inflammatory factors, such as growth factors, cytokines, and chemokines is generated
by stroma and tumor cells. Chronic and exhaustive secretion of these mediators
triggers the generation of myeloid‐derived suppressor cells (MDSCs) demonstrating
one of the key players engaged in tumor immunosuppression. In point of fact, direct
cell‐to‐cell contact is a prerequisite for immunosuppressive functions of MDSCs.
From the clinical perspective, the frequency of peripheral blood MDSCs is correlated
with clinical stage and therapeutic response in various cancers. Furthermore, MDSCs
are involved in chemoresistant settings. Altogether, it is a rational therapeutic
approach to block the fierce cycle in which MDSCs are developed and infiltrated to
favor cancer progression. In this review, we will summarize recent findings of MDSCs
in tumor progression and discuss potential therapeutic strategies that could be
evaluated in future clinical trials |