SPDL1 and melanoma: The latter could reflect the distinct roles played by the two variables in cancer patients—the anti-tumorigenic role of eosinophils, emerging in different human tumors such as colorectal, oral, and breast cancer, also associated to a long survival of melanoma patients in response to ICI therapy, and the immune suppressive role of sPD-L1, associated with shorter OS of cancer patients [38,42].