Breast cancer is the most common neoplasm diagnosed in women around the world. Checkpoint inhibitors, targeting the programmed death receptor-1 or ligand-1 (PD-1/PD-L1) axis, have dramatically changed the outcome of cancer treatment. These therapies have been recently considered as alternatives for treatment of breast cancers, in particular those with the triple-negative phenotype (TNBC). A further understanding of the regulatory mechanisms of PD-L1 expression is required to increase the benefit of PD-L1/PD-1 checkpoint immunotherapy in breast cancer patients. In this review, we will compile the most recent studies evaluating PD-1/PD-L1 checkpoint inhibitors in breast cancer. We review factors that determine the therapeutic success of PD-1/PD-L1 immunotherapies in this pathology. In particular, we focus on pathways that interconnect the epithelial-mesenchymal transition (EMT) with regulation of PD-L1 expression. We also discuss the relationship between cellular metabolic pathways and PD-L1 expression that are involved in the promotion of resistance in TNBC.

中文翻译：

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乳腺癌 PD-L1 检查点免疫疗法治疗成功的决定因素：关注上皮-间充质转化激活

乳腺癌是全世界女性诊断出的最常见的肿瘤。靶向程序性死亡受体-1 或配体-1 (PD-1/PD-L1) 轴的检查点抑制剂极大地改变了癌症治疗的结果。这些疗法最近被认为是治疗乳腺癌的替代方法，尤其是那些具有三阴性表型 (TNBC) 的乳腺癌。需要进一步了解 PD-L1 表达的调节机制，以增加 PD-L1/PD-1 检查点免疫疗法对乳腺癌患者的益处。在这篇综述中，我们将汇总评估乳腺癌中 PD-1/PD-L1 检查点抑制剂的最新研究。我们回顾了在这种病理学中决定 PD-1/PD-L1 免疫疗法治疗成功的因素。特别是，我们专注于将上皮-间质转化 (EMT) 与 PD-L1 表达调节相互关联的通路。我们还讨论了参与促进 TNBC 耐药性的细胞代谢途径和 PD-L1 表达之间的关系。