PDCD1 and hepatocellular carcinoma: Moreover, HCC and CRLM Tregs expressed significantly high CTLA4, CXCR4, PD-1, and ENTPD-1 (HCC vs HD, p < 0.001), while only Tregs from HCC significantly overexpressed ICOS (HCC vs HD, p < 0.05) (Fig. 1aii and Supplementary Fig. 1b and 2B).