两种抗体检测非小细胞肺癌PD-L1表达水平的对比分析

Comparison of Two Antibodies for The Detection of PD-L1 Expression in Non-Small Cell Lung Cancer

目的评价SP142和E1L3N两种兔单克隆抗体在临床肺癌标本中检测结果的一致性。方法连续收集了158例临床肺癌标本,制备成中性甲醛固定石蜡包埋的样品,采用SP142和E1L3N抗体,优化免疫组织化学方法检测PD-L1在肿瘤细胞和免疫细胞的表达情况。采用卡方检验和相关系数分析检出率和HScore得分的一致性和差异性。结果在158例肺癌组织中,SP142和E1L3N抗体检出的PD-L1总阳性率为54.4%(86/158)和62.7%(99/158)。两种抗体在肿瘤细胞染色分布较一致。当肿瘤细胞阳性比例(TPS)在1%≤TPS<5%、5%≤TPS<50%和TPS≥50%区间时,SP142抗体的检出阳性率分别为6.3%、17.1%和24.1%,E1L3N抗体的检出阳性率分别为7.6%、22.8%和26.6%,两种抗体的检测率总体上具有一致性(P=0.368)。当考虑染色强度时,肿瘤细胞HScore得分总体上相关性好(r=0.624,P=0.001)。但在所有TPS≥5%或TPS≥50%的阳性标本中,有43.9%(40/91)或42.0%(21/50)具有不一致性。在免疫炎症细胞检测中,两种抗体的染色分布异质性大。以1%为界值,SP142抗体和E1L3N抗体的检出率分别为19.6%和16.5%。结论 SP142和E1L3N两种兔单克隆抗体采用优化的免疫组织化学方法检测临床非小细胞肺癌标本中肿瘤细胞比例具有较好的一致性。两种抗体联合检测具有互补性,可能有助于检测出更多阳性患者用于临床治疗参考。

Objective This study aims to evaluate the PD-L1 expression testing concordance in Chinese non-small cell lung cancer(NSCLC)using two antibodies of SP142 and E1 L3 N.Methods Tissue samples of a consecutive 158 cases of NSCLC were made into formalin-fixed and paraffin embedded(FFPE)blocks.Optimized immunohistochemistry(IHC)using SP142 and E1 L3 N were established and then PD-L1 expression tests were carried out on the cancer tissue samples and immune cells.Tumor proportion score(TPS)and Histo-Score(HScore)were calculated for the evaluation ofPD-L1 expression.Chi square test and bivariate correlation test were performed for the statistical analysis of the data.Results In the cohort of 158 cases of NSCLC,PD-L1 expression positivity by SP142 and E1 L3 N were 54.4%(86/158)and 62.7%(99/158)separately.The staining patterns of these two antibodies on tumor cells were similar.When TPS set in intervals of 1%≤TPS<5%,5%≤TPS<50%,TPS≥50%,PD-L1 positivity by SP142 were 6.3%,17.1% and 24.1%,and positivity by E1 L3 N were 7.6%,22.8% and 26.6% separately,showing the similar results by two antibodies(P=0.368).Taking staining intensity into account,bivariate test showed HScore values of two antibodies had good correlation(r=0.624,P=0.001).However,in all positive samples if cut-point set as TPS≥5% or TPS≥50%,there are discrepancies of 43.9%(40/91)or 42.0%(21/50)of PD-L1 positivity between the two antibodies.In evaluating immune cells,the staining patterns of the two antibodies were heterogeneous,and if cut-off set at 1%,positivity of PD-L1 expression in immune cells were 19.6% and 16.5% separately.Conclusion Antibodies of SP142 and E1 L3 N have good concordance in terms of PD-L1 detection rate and staining patterns under the condition of optimized IHC.IHC by the two antibodies may be complimentary to detect PD-L1 positive cases as more as possible for clinical reference.