PDCD1 and cancer: Additionally, circUSP7 plays a role in resistance to anti-PD-1 therapy, highlighting circRNAs as key regulators of immune suppression in cancer and potential targets for improving immunotherapy efficacy.237 In gastric cancer, circDLG1 promotes immune evasion and PD-1 resistance by sponging miR-141-3p to enhance CXCL12 expression.