CD274 and breast cancer: Accumulating evidences have confirmed a series of biomarkers including PD-L1 expression, CD8+ T cell, tumor mutational burden (TMB), and microsatellite instability (MSI) could act as biomarkers to predict clinical outcome and therapeutic responses in BC (Patel & Kurzrock, 2015; Chan et al., 2019; Liu et al., 2020; Necchi et al., 2020).