To date, there is no standardized PD-L1 assay, immunohistochemistry (IHC) is the primary method for assessing PD-L1 expression in tumor samples, including five commonly used PD-L1 assay kits: SP142, SP263, 22C3, 28-8, and JS311, and their applications in TNBC are listed in Table 5. This evidence concerns the gene CD274 and neoplasm.