Background: The expression of programmed cell death ligand 1 (PD-L1) as a biomarker for immunotherapy in non-small cell lung cancer (NSCLC) is routinely detected in clinical pathology department. However, the spatial heterogeneity of PD-L1 expression in intrapulmonary tumors and extrapulmonary metastases is still a challenge for the clinical testing. This study aims to explore the differences of PD-L1 expression in test samples obtaining from different sites of NSCLC. This study may contribute to the detection strategy of PD-L1 in patients with advanced lung cancer.
Methods: One hundred and thirty-one cases of consecutively detected PD-L1 (22c3 assay, Dako) staining in metastatic NSCLC and 972 cases of non-paired intrapulmonary NSCLC were collected. The discrepancies of tumor proportion score (TPS) of PD-L1 expression in intrapulmonary samples and extrapulmonary metastatic samples of different sites were compared.
Results: The positive expression rate of PD-L1 in extrapulmonary metastatic NSCLC (TPS ≥ 1%) was 61.83%, and the TPS was significantly higher than that in intrapulmonary tumors (P=0.03). The PD-L1 scores of the specimens obtained from different sites were significantly different (P=0.007). The positive rates of PD-L1 in liver and adrenal metastases were 85.71% and 77.78% respectively, and their TPS were significantly higher than that of the intrapulmonary samples (P<0.05). The positive rates of PD-L1 in lymph node, bone, brain, soft tissue, and pleural metastases was 40.00%-66.67%, with no significant differences compared to intrapulmonary tumors. The analysis of histological subtype and sample type showed that the PD-L1 score of extrapulmonary samples of adenocarcinoma subtype or surgical specimen was significantly higher than that of intrapulmonary tumors. The analysis of clinicopathological parameters showed that the PD-L1 positive expression or high expression were significantly correlated with male patients, smoking history, and epidermal growth factor receptor (EGFR) wild type.
Conclusions: The expression of PD-L1 in metastatic NSCLC is generally higher than that in intrapulmonary tumor, and the positive rate of PD-L1 expression was discrepant in different sites of specimen. The differences of PD-L1 score between extrapulmonary metastatic samples and intrapulmonary samples may be associated with different metastatic sites, histological subtype, and specimen type.
【中文题目：非小细胞肺癌不同部位组织样本PD-L1 表达水平比较研究】 【中文摘要：背景与目的 程序性死亡配体1（programmed cell death ligand 1, PD-L1）作为非小细胞肺癌（non-small cell lung cancer, NSCLC）免疫治疗患者分层标志物已进入临床病理常规检测。然而PD-L1表达在肺内和肺外不同转移部位的空间异质性是困扰临床检测的难题。本研究旨在探讨NSCLC不同部位组织样本的PD-L1表达评分的差异，从而有助于晚期肺癌患者的PD-L1检测策略的制定。方法 回顾性收集PD-L1（22c3抗体，Dako）临床病理连续检测的131例肺外转移性NSCLC以及同期非配对肺内肿瘤972例进行对照分析，对比肺外与肺内肿瘤组织样本检测的PD-L1肿瘤阳性比例评分（tumor proportion score, TPS）差异。结果 肺外转移性NSCLC的PD-L1阳性表达率（TPS≥1%）为61.83%，TPS评分显著高于同期肺内肿瘤（P=0.03）。不同部位组织样本的PD-L1表达评分具有显著差异（P=0.007）。肝脏和肾上腺转移瘤的PD-L1阳性率高，分别为85.71%和77.78%，其TPS评分均显著高于肺内肿瘤（P<0.05）。淋巴结、骨、脑、软组织和胸膜转移瘤的PD-L1表达率为40.00%-66.67%，TPS评分与肺内肿瘤无显著差异。组织学和样本类型分析显示，腺癌类型和手术切除的肺外样本PD-L1表达评分显著高于同类型肺内肿瘤。临床病理参数分析显示，PD-L1阳性表达和高表达均与患者男性、吸烟史以及表皮生长因子受体（epidermal growth factor receptor, EGFR）野生型显著相关。结论 肺外转移性NSCLC样本的PD-L1表达评分高于肺内肿瘤，且不同部位组织样本的PD-L1表达阳性率存在差异。肺外转移性肿瘤与肺内肿瘤的PD-L1检测差异可能与不同转移部位、组织学和样本类型相关。 】 【中文关键词：肺肿瘤；程序性死亡配体1；异质性；肿瘤阳性比例评分】.
Keywords: Heterogeneity; Lung neoplasms; Programmed cell death ligand 1; Tumor proportion score.