For example, Martinez et al. found significantly reduced serum levels of let-7a and miR-26a in liquid biopsies of HN-SCC patients [63], and reduced expression of let-7a was reported in HN-SCC tissue, where this miRNA was linked to tumor immune checkpoint evasion due to accumulation of its target, the programmed cell death ligand 1 (PD-L1) [64,65]. This evidence concerns the gene CD274 and neoplasm.