CD274 and breast cancer: Since the PD-L1-positive subgroup patients benefit the most from undergoing anti-PD-1/PD-L1 therapy (Leighl et al., 2019; Kwapisz, 2021), PD-L1 immunohistochemistry (IHC) has been approved by the Food and Drug Administration (FDA) to assess CBI response in patients with a variety of malignancies, including breast cancer, non-small cell lung cancer, and melanoma (Brody et al., 2017; Kwapisz, 2021; Deng et al., 2022; Wolchok et al., 2022).