CD274 and breast cancer: Accordingly, emerging evidence have revealed that local immunomodulatory factors (e.g. IFN-γ released by TILs), or the activation of oncogenic signaling pathways (e.g. the PI3K pathway) can promote the expression of PD-L1, which has been shown to be enriched in triple-negative/basal-like breast cancer, and to be associated with good outcome and response to chemotherapy in patients with TNBC [6, 10–14].