As immune checkpoint molecules such as T-cell immunoglobulin mucin 3 emerge from Tregs and block the activation of effector T cells, high Treg expression has been reported to be associated with poor prognosis in HCC patients following programmed cell death 1 (PD-1)/PD-L1 therapy [145]. The gene discussed is HAVCR2; the disease is hepatocellular carcinoma.