PDCD1 and metastatic malignant neoplasm: In this study, we therefore evaluated whether endogenous GC at the initiation of ICIs may impair the efficacy of PD-1/PD-L1 inhibitors in patients with advanced or metastatic cancer, and further explored whether endogenous GC levels are associated with circulating and tumor-infiltrating T cell subpopulations, and cytokine secretion.