CD274 and neoplasm: Therefore, the concept of immune escape in TNBC focuses on the development of an immunosuppressed tumour microenvironment [127] that consists of immune checkpoint proteins such as programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) [128,129] and other components such as T regulatory cells [130] and myeloid-derived immunosuppressor cells (MDSCs) [131] which supports the progression of this metastatic subtype.