As T cell exhaustion due to PD-L1/PD1 inhibitory receptor signaling impairs T cell proliferation and effector functions, the relationship between tumoral BLIMP1 protein expression and exhausted T cells in HCC specimens was examined by profiling the content and function of CD8+ T cells in tumor-infiltrating T lymphocytes (TILs) using flow cytometry in cohort 1 (40 patients with HCC showing diverse tumoral BLIMP1 protein expression). The gene discussed is PDCD1; the disease is hepatocellular carcinoma.