CD274 and breast cancer: A total of 112 immune-related gene levels were found to decrease in BC BMs compared to primary BCs, including PD-L1 and cytotoxic T-lymphocyte antigen 4 (CTLA-4) (false discovery rate < 0.01, log2 fold-change > 1.5), which are involved in cytokine–chemokine signaling, immune cells migration, matrix remodeling, and metastasis [48].