As the development of checkpoint inhibitor therapy, five immunotherapy agents targeting the primarily targeting programmed cell death-1 protein (PD-1) or its ligand (PD-L1) pathway have been approved by the US Food and Drug Administration (FDA) for BC patients, including atezolizumab, pembrolizumab, avelumab, nivolumab, and durvalumab. This evidence concerns the gene PDCD1 and breast cancer.