Department of Public Health, University of Naples 'Federico II', Naples, Italy.
J Clin Pathol. 2019 Jun;72(6):412-417. doi: 10.1136/jclinpath-2019-205732. Epub 2019 Mar 7.
Our laboratory is a centralised centre receiving routine non-small cell lung cancer (NSCLC) samples for programmed death ligand-1 (PD-L1) immunohistochemical (IHC) evaluation. Since literature data are not concordant here we review our clinical records to assess the rate of PD-L1 positive and negative NSCLC cases in real-world practice.
PD-L1 expression was evaluated by a validated 22C3 IHC laboratory developed test on 211 prospectively collected routine NSCLC samples, received from 10 outside institutions. PD-L1 expression was assessed by the tumour proportion score (TPS) and reported by using a three cut-point system: TPS<1, TPS 1%-49% and TPS≥50%.
Overall, 193 out of 211 samples (91.5%) meet the criteria for adequacy (more than 100 viable neoplastic cells). In 62.7% (121/193) of samples TPS was <1%; 17.6% of samples (34/193) expressed PD-L1 with a TPS of 1%-49% and 19.7% (38/193) with a TPS of >50%. There was no significant difference in PD-L1 expression rates between different histotypes and site of sampling. Instead, a statistically significant difference was associated to the type of samples: in fact, cytological samples were more frequently negative for PD-L1 expression (TPS<1%) and less often displayed PD-L1 expression at high levels (TPS>50%) than surgical resections and biopsies.
We present a referral laboratory experience on IHC PD-L1 expression of prospectively collected routine NSCLC samples. Data from the real-world practice can better clarify the percentage of PD-L1 positive and negative cases, to establish benchmarks for good practice standards.
本实验室是一个接收常规非小细胞肺癌（NSCLC）样本进行程序性死亡配体-1（PD-L1）免疫组织化学（IHC）评估的中心实验室。由于目前文献数据并不一致，我们回顾了临床记录，以评估真实世界实践中 PD-L1 阳性和阴性 NSCLC 病例的比例。
通过验证的 22C3 IHC 实验室开发测试，对 211 例来自 10 家外部机构的前瞻性收集的常规 NSCLC 样本进行 PD-L1 表达评估。PD-L1 表达通过肿瘤比例评分（TPS）进行评估，并使用三切点系统进行报告：TPS<1、TPS 1%-49%和 TPS≥50%。
总体而言，211 例样本中 193 例（91.5%）符合充分性标准（有超过 100 个存活的肿瘤细胞）。在 193 例样本中，62.7%（121/193）的 TPS<1%；17.6%（34/193）的样本表达 PD-L1，TPS 为 1%-49%，19.7%（38/193）的样本 TPS>50%。不同组织类型和采样部位之间 PD-L1 表达率无显著差异。相反，PD-L1 表达与样本类型有统计学显著差异：事实上，细胞学样本更常表现为 PD-L1 表达阴性（TPS<1%），而很少表现为高水平 PD-L1 表达（TPS>50%），与手术切除和活检相比。
我们展示了一个前瞻性收集常规 NSCLC 样本的参考实验室 IHC PD-L1 表达经验。真实世界实践的数据可以更清楚地阐明 PD-L1 阳性和阴性病例的比例，为建立良好实践标准的基准提供依据。
