ROS1 融合的患病率相对较低（0.6-2.0%），但在肺腺癌（LUAD）中是可靶向的驱动因素。需要进行稳健且低成本的测试，例如免疫组织化学 (IHC)，以筛选可能携带这种融合的患者。目的是使用体外诊断 (IVD) 标记的克隆 SP384 进行 IHC 筛查，然后在预定义子集中进行验证性分子分析，研究临床注释的欧洲 I-III 期 LUAD 队列中 ROS1 融合的患病率。在组织微阵列中构建，使用即用型试剂盒中的 SP384 克隆和 Ventana 免疫染色仪对 ROS1 表达进行免疫染色。经过外部质量控制后，由经过培训的病理学家进行分析。染色强度至少为 2（任意百分比的肿瘤细胞）被认为是 IHC 阳性 (ROS1 IHC)。随后，ROS1 IHC 病例与 IHC0 和 IHC1 病例进行 1:1:1 匹配，并进行正交 ROS1 FISH 和基于 RNA 的检测。ROS1 阳性表达 (ROS1 IHC)（定义为 IHC 2 /3）的患病率为 4% （866 个 LUAD 中的 35 个）。通过基于 FISH/RNA 的检测对 28 例 ROS1 IHC 病例进行了分析，其中只有 2 例具有确认的 ROS1 基因融合，对应的 ROS1 基因融合患病率下限为 0.23%。它们代表在 ROS1 IHC 病例中识别融合的概率为 7%。这两个确诊病例都是仅有的四个拥有足够材料且 H 评分≥ 200 的病例之一，因此在 H 评分被视为强阳性的病例中，有 50% 的概率识别出 ROS1 基因融合。所有匹配的 ROS1 IHC-（IHC0 和 IHC1）病例也通过基于 FISH/RNA 的检测呈阴性，导致 ROS1 IHC- 病例缺乏 ROS1 融合的可能性为 100%。 LUAD I 期中 ROS1 融合的患病率-III 欧洲队列相对较低。使用 SP384 克隆的 ROS1 IHC 可用于排除 ROS1 基因融合阴性病例。版权所有 © 2024 Elsevier B.V. 保留所有权利。

ROS1 fusion is a relatively low prevalence (0.6-2.0%) but targetable driver in lung adenocarcinoma (LUAD). Robust and low-cost tests, such as immunohistochemistry (IHC), are desirable to screen for patients potentially harboring this fusion. The aim was to investigate the prevalence of ROS1 fusions in a clinically annotated European stage I-III LUAD cohort using IHC screening with the in vitro diagnostics (IVD)-marked clone SP384, followed by confirmatory molecular analysis in pre-defined subsets.Resected LUADs constructed in tissue microarrays, were immunostained for ROS1 expression using SP384 clone in a ready-to-use kit and Ventana immunostainers. After external quality control, analysis was performed by trained pathologists. Staining intensity of at least 2+ (any percentage of tumor cells) was considered IHC positive (ROS1 IHC + ). Subsequently, ROS1 IHC + cases were 1:1:1 matched with IHC0 and IHC1 + cases and subjected to orthogonal ROS1 FISH and RNA-based testing.The prevalence of positive ROS1 expression (ROS1 IHC + ), defined as IHC 2+/3+, was 4 % (35 of 866 LUADs). Twenty-eight ROS1 IHC + cases were analyzed by FISH/RNA-based testing, with only two harboring a confirmed ROS1 gene fusion, corresponding to a lower limit for the prevalence of ROS1 gene fusion of 0.23 %. They represent a 7 % probability of identifying a fusion among ROS1 IHC + cases. Both confirmed cases were among the only four with sufficient material and H-score ≥ 200, leading to a 50 % probability of identifying a ROS1 gene fusion in cases with an H-score considered strongly positive. All matched ROS1 IHC- (IHC0 and IHC1 + ) cases were also found negative by FISH/RNA-based testing, leading to a 100 % probability of lack of ROS1 fusion for ROS1 IHC- cases.The prevalence of ROS1 fusion in an LUAD stage I-III European cohort was relatively low. ROS1 IHC using SP384 clone is useful for exclusion of ROS1 gene fusion negative cases.Copyright © 2024 Elsevier B.V. All rights reserved.