ERBB2 and breast cancer: However, we (Foukakis et al., 2018; Matikas et al., 2018) and others (Denkert et al., 2018) have shown that immune function, expressed as immune‐related gene expression or abundance of TILs, is also a driver for chemosensitivity in ER+/HER2− BC, implying that the results of the present study might be due to increased efficacy of CT in high PD‐L1 expressors.