In addition, previous studies have demonstrated increased expression of PD-L1 in CSCs of multiple cancers, resulting in more aggressive resistance of CSCs to anti-PD-1/PD-L1 therapies, and CSC-intrinsic PD-L1 pathways take a nonnegligible role in cancer progression and metastasis in an immune independent way 5-11. The gene discussed is PDCD1; the disease is cancer.