ABSTRACT Immunohistochemical (IHC) stain for PD-L1 as a biomarker for immunotherapy is recommended in non-small cell lung cancer (NSCLC). Under the FDA, the selection of patients for pembrolizumab requires companion diagnostic testing using the Dako Agilent PD-L1 IHC 22C3 pharmDx kit performed on the Dako Autostainer Link 48 platform. However, because it is not widely available, there is need for cross-platform validation. Existing studies provide incomplete protocol detail. In our study, 73 lung tumors were stained using the FDA-approved test (‘gold standard’). The same blocks were stained using two different models of the Ventana DISCOVERY platform (ULTRA, n = 73 and XT, n = 70) using different parameters, and interpreted by three pathologists. The ULTRA group met College of American Pathologists (CAP) validation criteria (concordance 91.8%) while the XT group did not (concordance 67.1%). Using tumor proportion score (TPS) ≥1% and TPS ≥50% as cut-offs, the ULTRA protocol had higher sensitivity (97.8% and 91.7%) than XT (73.3% and 60.9%) and similar specificity (ULTRA 88.9% and 100%, XT 88% and 100%). Discordance between ULTRA and XT was 27%, and in all these cases ULTRA was concordant with gold standard. Interobserver reliability was substantial for ULTRA and almost perfect for XT, providing evidence that staining rather than observer variability accounts for XT’s inferior performance. Cross-validation of the clinically used 22C3 anti PD-L1 antibody test with substantial interobserver agreement is possible on the commonly used the Ventana DISCOVERY ULTRA automated instrument, while the validation failed on the XT. Cautious attention to detail must be paid when choosing cross-validation parameters.

中文翻译：

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在两个 Ventana DISCOVERY 自动染色器模型上验证 PD-L1 克隆 22C3 免疫组织化学染色：详细方案、测试性能特征和观察者间可靠性分析

摘要 在非小细胞肺癌 (NSCLC) 中，推荐将 PD-L1 的免疫组织化学 (IHC) 染色作为免疫治疗的生物标志物。根据 FDA 规定，选择帕博利珠单抗的患者需要使用 Dako Agilent PD-L1 IHC 22C3 pharmDx 试剂盒在 Dako Autostainer Link 48 平台上进行伴随诊断测试。但是，因为它没有广泛使用，所以需要跨平台验证。现有的研究提供了不完整的协议细节。在我们的研究中，使用 FDA 批准的测试（“金标准”）对 73 个肺肿瘤进行了染色。使用不同参数的 Ventana DISCOVERY 平台的两种不同模型（ULTRA，n = 73 和 XT，n = 70）对相同的块进行染色，并由三位病理学家进行解释。ULTRA 组符合美国病理学家学会 (CAP) 验证标准（一致性 91。8%) 而 XT 组没有 (一致性 67.1%)。以肿瘤比例评分 (TPS) ≥ 1% 和 TPS ≥ 50% 作为临界值，ULTRA 方案比 XT（73.3% 和 60.9%）具有更高的敏感性（97.8% 和 91.7%）和相似的特异性（ULTRA 88.9% 和100%、XT 88% 和 100%）。ULTRA 和 XT 之间的不一致性为 27%，在所有这些情况下，ULTRA 都与金标准一致。ULTRA 的观察者间可靠性非常高，XT 几乎完美，这证明染色而不是观察者可变性是 XT 性能较差的原因。临床使用的 22C3 抗 PD-L1 抗体测试在常用的 Ventana DISCOVERY ULTRA 自动化仪器上的交叉验证与观察者间基本一致是可能的，而在 XT 上验证失败。