For example, IL-6-mediated STAT3 activation promotes the production of immunosuppressive molecules, such as vascular endothelial growth factor and arginase, and induces immunosuppressive cells, such as myeloid-derived suppressor cells (MDSCs) (Zhou et al., 2017), which reportedly serve as biomarkers of OS in patients with melanoma treated with ICI (Meyer et al., 2014). Here, STAT3 is linked to melanoma.