Recent findings on the PD-1/PD-L1 Axis in breast cancer: Molecular mechanisms, immunotherapeutic potentials, and clinical implications.

Originally, breast cancer was not thought to be a very immunogenic malignancy. Recent research, however, has revealed that certain aggressive triple-negative breast tumors are immunogenic and demonstrate chemoresistance. In several cancer forms that are resistant to traditional treatments, including non-small cell lung cancer and melanoma, the discovery of immunotherapy via immune checkpoint blockage produced long-lasting results. Multiple additional cancer types have also seen notable improvements because of immunotherapy. But one of the malignancies that hasn't yet benefited from immunotherapy's surge is breast cancer (BC). When given as single-drug treatment or in conjunction with traditional therapies, PD1/PD-L1 pathway antagonists have shown encouraging outcomes in the evaluation of BC in the past few years, specifically in the triple-negative subtype, which has an aggressive profile and poor prognosis. Nevertheless, tumor cells can evade the immune system's activity by suppressing cytotoxic T cells through these checkpoint pathways. The T cells can start directly eliminating tumor cells and secreting immunostimulatory cytokines once they are awakened. The findings of the most current research assessing immune checkpoint inhibitors in BC will be presented in this review. In the present review study, we emphasize in PD-1/PD-L1 molecular mechanisms, upstream signaling pathways, clinical implications, and therapeutic potential in BC.