CD4 and melanoma: On the one hand, the knockout of miR-155 in CD4+CD8+ T cells in modified mice enhanced the efficacy of immune checkpoint inhibitors (ICIs) when using B16 melanoma cells [32], On the other hand, in a human melanoma cell line mel1359 overexpressing miR-155 and co-cultured with peripheral blood mononuclear cells, there was an enhancement in the efficacy of ICIs [22].