Department of Pathology, Cancer Center Amsterdam, Vrije University, Amsterdam University Medical Center, Amsterdam, The Netherlands.
Department of Pathology, Erasmus MC Cancer Institute, Rotterdam, The Netherlands.
J Thorac Oncol. 2021 May;16(5):798-806. doi: 10.1016/j.jtho.2021.01.1619. Epub 2021 Feb 12.
RET gene fusions are established oncogenic drivers in 1% of NSCLC. Accurate detection of advanced patients with RET fusions is essential to ensure optimal therapy choice. We investigated the performance of fluorescence in situ hybridization (FISH) as a diagnostic test for detecting functional RET fusions.
Between January 2016 and November 2019, a total of 4873 patients with NSCLC were routinely screened for RET fusions using either FISH (n = 2858) or targeted RNA next-generation sequencing (NGS) (n = 2015). If sufficient material was available, positive cases were analyzed by both methods (n = 39) and multiple FISH assays (n = 17). In an independent cohort of 520 patients with NSCLC, whole-genome sequencing data were investigated for disruptive structural variations and functional fusions in the RET and compared with ALK and ROS1 loci.
FISH analysis revealed RET rearrangement in 48 of 2858 cases; of 30 rearranged cases double tested with NGS, only nine had a functional RET fusion. RNA NGS yielded RET fusions in 14 of 2015 cases; all nine cases double tested by FISH had RET locus rearrangement. Of these 18 verified RET fusion cases, 16 had a split signal and two a complex rearrangement by FISH. By whole-genome sequencing, the prevalence of functional fusions compared with all disruptive events was lower in the RET (4 of 9, 44%) than the ALK (27 of 34, 79%) and ROS1 (9 of 12, 75%) loci.
FISH is a sensitive but unspecific technique for RET screening, always requiring a confirmation using an orthogonal technique, owing to frequently occurring RET rearrangements not resulting in functional fusions in NSCLC.
RET 基因融合在 1%的 NSCLC 中确立了致癌驱动因素。准确检测晚期有 RET 融合的患者对于确保最佳治疗方案的选择至关重要。我们研究了荧光原位杂交（FISH）作为检测功能性 RET 融合的诊断测试的性能。
2016 年 1 月至 2019 年 11 月，共有 4873 例 NSCLC 患者常规接受 RET 融合检测，分别采用 FISH（n=2858）或靶向 RNA 下一代测序（NGS）（n=2015）。如果有足够的材料，阳性病例分别用两种方法（n=39）和多种 FISH 检测（n=17）进行分析。在 520 例 NSCLC 患者的独立队列中，研究了全基因组测序数据中 RET 基因的结构变异和功能融合，并与 ALK 和 ROS1 基因座进行了比较。
FISH 分析显示，在 2858 例中发现 48 例存在 RET 重排；在 30 例经 NGS 双检测的重排病例中，只有 9 例存在功能性 RET 融合。NGS 在 2015 例中发现了 14 例 RET 融合；在 FISH 双检测的 9 例中，所有病例均存在 RET 基因座重排。在这 18 例经证实的 RET 融合病例中，16 例 FISH 检测显示有分离信号，2 例显示复杂重排。通过全基因组测序，与所有结构变异事件相比，RET 基因座（9 例中有 4 例，44%）中功能性融合的发生率低于 ALK（34 例中有 27 例，79%）和 ROS1（12 例中有 9 例，75%）基因座。
FISH 是一种敏感但非特异性的 RET 筛选技术，由于 NSCLC 中经常发生的 RET 重排并不导致功能性融合，因此始终需要使用正交技术进行确认。
