CD274 and cancer: Immune checkpoint proteins such as programmed death-ligand 1 (PD-L1), tumor mutational burden (TMB), and tumor-infiltrating lymphocytes (TILs), are used as biomarkers to predict the efficacy of ICIs against cancers, particularly in metastatic TNBC (Geurts and Kok 2023; Muenst et al. 2014; Qureshi et al. 2022).