A recent cohort study including 36 ccRCC patients conducted by Lucarelli and colleagues [92] reported that tumor expressing high levels vs. those expressing low levels of the transmembrane glycoprotein mucin 1 (MUC1) were associated with an altered metabolism, higher vascularization, lower immune infiltration and higher M2-tumor associated macrophage response, and lower PD-L1 expression, suggesting these tumors would theorically derive less benefit from ICI. Here, MUC1 is linked to nonpapillary renal cell carcinoma.