PDCD1 and adrenal cortex carcinoma: Interestingly, FDX1 was significantly negatively correlated with the expression of many immune checkpoint genes in ACC, especially PD-1 (PDCD1), PD-L1(CD274), CTLA4 and other important immunotherapy targets, which may also be closely related to the immune escape mechanism of ACC tumor cells (Jiang et al., 2019).