Targeting myeloid-derived suppressor cells for cancer therapy

The emergence and clinical application of immunotherapy is considered a promising breakthrough in cancer treatment. Accordingto the literature, immune checkpoint blockade (ICB) has achieved positive clinical responses in different cancer types, althoughits clinical efficacy remains limited in some patients. The main obstacle to inducing effective antitumor immune responses withICB is the development of an immunosuppressive tumor microenvironment. Myeloid-derived suppressor cells (MDSCs), as majorimmune cells that mediate tumor immunosuppression, are intimately involved in regulating the resistance of cancer patients toICB therapy and to clinical cancer staging and prognosis. Therefore, a combined treatment strategy using MDSC inhibitors andICB has been proposed and continually improved. This article discusses the immunosuppressive mechanism, clinical significance,and visualization methods of MDSCs. More importantly, it describes current research progress on compounds targeting MDSCs toenhance the antitumor efficacy of ICB.