Functional studies have confirmed that knockdown of circUHRF1 restores NK cell cytotoxicity and enhances the efficacy of anti-programmed cell death protein-1 (PD-1) therapy, underscoring its potential as a therapeutic target.148 Similarly, in non-small cell lung cancer, circ-CPA4 facilitates immune escape by spongingmiR-377, resulting in overexpression of PD-L1 and immune evasion and escape. Here, PDCD1 is linked to non-small cell lung carcinoma.