CD274 and metastatic neoplasm: To understand the molecules active in the nonresponsive metastatic TNBC, we stained the metastatic tumors with anti-PD-L1 and found that the metastatic tumors from the untreated groups had extremely high to moderate levels of PD-L1 expression, while those from the treated groups had mild to low levels of PD-L1 expression (Supplementary Figure S13A,B).