Although anti-PD-1 therapy is not known to modulate the diversity of tumor-reactive T cell clones32,33, we hypothesized that the addition of the PTCV to anti-PD-1 therapy would lead to both an increase in abundance and a broadening of the circulating HCC-reactive T cell clonal repertoire, which would subsequently traffic to the tumor microenvironment. This evidence concerns the gene PDCD1 and hepatocellular carcinoma.