Taube Janis M, Young Geoffrey D, McMiller Tracee L, Chen Shuming, Salas January T, Pritchard Theresa S, Xu Haiying, Meeker Alan K, Fan Jinshui, Cheadle Chris, Berger Alan E, Pardoll Drew M, Topalian Suzanne L
Department of Dermatology, Johns Hopkins University School of Medicine, Baltimore, Maryland. Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland. Department of Oncology, Sidney Kimmel Comprehensive Cancer Center and Johns Hopkins University School of Medicine, Baltimore, Maryland.
Department of Otolaryngology, Johns Hopkins University School of Medicine, Baltimore, Maryland.
Clin Cancer Res. 2015 Sep 1;21(17):3969-76. doi: 10.1158/1078-0432.CCR-15-0244. Epub 2015 May 5.
Blocking the immunosuppressive PD-1/PD-L1 pathway has antitumor activity in multiple cancer types, and PD-L1 expression on tumor cells and infiltrating myeloid cells correlates with the likelihood of response. We previously found that IFNG (interferon-gamma) was overexpressed by tumor-infiltrating lymphocytes in PD-L1(+) versus PD-L1(-) melanomas, creating adaptive immune resistance by promoting PD-L1 display. This study was undertaken to identify additional factors in the PD-L1(+) melanoma microenvironment coordinately contributing to immunosuppression.
Archived, formalin-fixed paraffin-embedded melanoma specimens were assessed for PD-L1 protein expression at the tumor cell surface with IHC. Whole-genome expression analysis, quantitative (q)RT-PCR, IHC, and functional in vitro validation studies were used to assess factors differentially expressed in PD-L1(+) versus PD-L1(-) melanomas.
Functional annotation clustering based on whole-genome expression profiling revealed pathways upregulated in PD-L1(+) melanomas, involving immune cell activation, inflammation, and antigen processing and presentation. Analysis by qRT-PCR demonstrated overexpression of functionally related genes in PD-L1(+) melanomas, involved in CD8(+) T-cell activation (CD8A, IFNG, PRF1, and CCL5), antigen presentation (CD163, TLR3, CXCL1, and LYZ), and immunosuppression [PDCD1 (PD-1), CD274 (PD-L1), and LAG3, IL10]. Functional studies demonstrated that some factors, including IL10 and IL32-gamma, induced PD-L1 expression on monocytes but not tumor cells.
These studies elucidate the complexity of immune checkpoint regulation in the tumor microenvironment, identifying multiple factors likely contributing to coordinated immunosuppression. These factors may provide tumor escape mechanisms from anti-PD-1/PD-L1 therapy, and should be considered for cotargeting in combinatorial immunomodulation treatment strategies.
阻断免疫抑制性PD-1/PD-L1通路在多种癌症类型中具有抗肿瘤活性，肿瘤细胞和浸润性髓样细胞上的PD-L1表达与反应可能性相关。我们之前发现，在PD-L1(+)与PD-L1(-)黑色素瘤中，肿瘤浸润淋巴细胞过度表达IFNG（干扰素-γ），通过促进PD-L1展示产生适应性免疫抵抗。本研究旨在确定PD-L1(+)黑色素瘤微环境中协同促成免疫抑制的其他因素。
使用免疫组化（IHC）评估存档的福尔马林固定石蜡包埋黑色素瘤标本肿瘤细胞表面的PD-L1蛋白表达。采用全基因组表达分析、定量（q）RT-PCR、IHC和体外功能验证研究来评估在PD-L1(+)与PD-L1(-)黑色素瘤中差异表达的因素。
基于全基因组表达谱的功能注释聚类揭示了PD-L1(+)黑色素瘤中上调的通路，涉及免疫细胞激活、炎症以及抗原加工和呈递。qRT-PCR分析表明，在PD-L1(+)黑色素瘤中，参与CD8(+) T细胞激活（CD8A、IFNG、PRF1和CCL5）、抗原呈递（CD163、TLR3、CXCL1和LYZ）以及免疫抑制[PDCD1（PD-1）、CD274（PD-L1）和LAG3、IL10]的功能相关基因过表达。功能研究表明，一些因素，包括IL10和IL32-γ，可诱导单核细胞而非肿瘤细胞上的PD-LI表达。
这些研究阐明了肿瘤微环境中免疫检查点调节的复杂性，确定了可能促成协同免疫抑制的多种因素。这些因素可能为肿瘤提供逃避抗PD-1/PD-L1治疗的机制，在联合免疫调节治疗策略中应考虑将其作为共同靶点。
