HAVCR2 and hepatocellular carcinoma: CircUHRF1 is secreted via exosomes by HCC cells into the surrounding microenvironment and by sequestering and preventing miR-449c-5p binding to the checkpoint target gene “T cell immunoglobulin and mucin domain 3” (TIM-3), triggers natural killer (NK) cell dysfunction, immune evasion and resistance to anti-PD-1 immunotherapy [205].