PDCD1 and hepatocellular carcinoma: An elegant study by Yin C and coworkers demonstrated that HCC-derived miR-146-5p-containing exosomes are able to induce M2 polarization of TAMs that, in turn, exert an inhibitor action on T cells by inducing the expression of PD-1 and CTLA4 and blocking the production of pro-inflammatory cytokines.