Human leukocyte antigen (HLA) class I antigen-processing machinery (APM) plays a crucial role in the synthesis and expression of HLA class I tumor antigen-derived peptide complexes; the latter mediate the recognition and elimination of malignant cells by cognate T cells. Defects in HLA class I APM component expression and/or function are frequently found in cancer cells, providing them with an immune escape mechanism that has relevance in the clinical course of the disease and in the response to T-cell–based immunotherapy. The majority of HLA class I APM defects (>75%) are caused by epigenetic mechanisms or dysregulated signaling and therefore can be corrected by strategies that counteract the underlying mechanisms. Their application in oncology is likely to improve responses to T-cell–based immunotherapies, including checkpoint inhibition.

人类白细胞抗原（HLA）I类抗原加工机器（APM）在HLA I类肿瘤抗原衍生肽复合物的合成和表达中起着至关重要的作用；后者介导同源 T 细胞对恶性细胞的识别和消除。HLA I 类 APM 成分表达和/或功能的缺陷经常在癌细胞中发现，为它们提供了一种免疫逃逸机制，该机制与疾病的临床病程和对基于 T 细胞的免疫疗法的反应相关。大多数 HLA I 类 APM 缺陷 (>75%) 是由表观遗传机制或信号失调引起的，因此可以通过抵消潜在机制的策略来纠正。它们在肿瘤学中的应用可能会改善对基于 T 细胞的免疫疗法的反应，包括检查点抑制。