CD8A and hepatocellular carcinoma: Recent studies have shown that circCCAR1 is significantly enriched in exosomes derived from HCC and it promotes immune evasion of cancer cells and resistance to anti-PD-1 immune therapy by acting on the miR-127-5p/WT1 associated protein (WTAP) axis, increasing the stability of PD-1 protein, and causing dysfunction of CD8+ T cells (Hu et al., 2023).