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). Here, PDCD1 is linked to neoplasm.