CD8A and neoplasm: A paradigm is circRNA-002178, which operates in a dual capacity: it directly upregulates PD-L1 expression in tumor cells by sequestering miR-34a (Yang et al., 2020; Wang et al., 2023); and is subsequently packaged into exosomes to be transferred to CD8+ T cells, where it suppresses miR-28-5p to elevate PD-1 expression.