Targeting polymorphonuclear myeloid-derived suppressor cells in the immunosuppressive tumor microenvironment for cancer immunotherapy.

Tumor-driven immune suppression is a critical mechanism by which cancer cells evade the host immune system, leading to tumor growth and metastasis. The tumor immune microenvironment contains a large population of immune-suppressing myeloid cells, which play a key role in tumor development and drug resistance to existing immunotherapy. Polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) are important components of the immunosuppressive microenvironment. Uncovering the molecular mechanisms of PMN-MDSCs and finding specific targets for PMN-MDSCs to regulate tumor immune microenvironment is the focus and challenge of current immunotherapy. In a recent issue of Nature, Wang and colleagues revealed that CD300ld on PMN-MDSCs is required for tumor-driven immune suppression(1), this provided a new target for cancer immunotherapy, The study identified CD300ld as a novel, highly conserved tumor immunosuppressive receptor. CD300ld is highly expressed specifically on PMN-MDSCs and is a key receptor in regulating the recruitment and immunosuppressant function of PMN-MDSCs. Targeting CD300ld can reshape the tumor immune microenvironment by inhibiting the recruitment and function of PMN-MDSCs, resulting in broad-spectrum anti-tumor effects. CD300ld target shows good safety, conservation, anti-tumor effectiveness, and synergism with the Programmed death-1 target, which is expected to become a new ideal target for tumor immunotherapy.