Introduction: Genomic alterations affecting splice sites of MNNG HOS transforming gene (MET) exon 14 were recently identified in NSCLC patients. Objective responses to MET tyrosine kinase inhibitors have been reported in these patients. Thus, detection of MET exon 14 splice site mutations represents a major challenge. So far, most of these alterations were found by full‐exome sequencing or large capture‐based next‐generation sequencing (NGS) panels, which are not suitable for routine diagnosis. Methods: Aiming to provide a molecular testing method applicable in routine practice, we first developed a fragment‐length analysis for detecting deletions in introns flanking MET exon 14. Second, we designed an optimized targeted NGS panel called CLAPv1, covering the MET exon 14 and flanking regions in addition to the main molecular targets usually covered in genomic testing. In patients with MET exon 14 mutations, MET gene amplification, gene copy number and MET receptor expression were also determined. Results: Among 1514 formalin‐fixed paraffin‐embedded NSCLC samples, nonoptimized NGS allowed detection of MET exon 14 mutations in only 0.3% of the patients, and fragment length analysis detected deletions in 1.1% of the patients. Combined, the optimized CLAPv1 panel and fragment‐length analysis implemented for routine molecular testing revealed MET exon 14 alterations in 2.2% of 365 additional NSCLC patients. MET gene amplification or high gene copy number was observed in 6 of 30 patients (20%) harboring MET exon 14 mutations. Conclusions: These results show that optimized targeted NGS and fragment‐length analysis improve detection of MET alterations in routine practice.

中文翻译：

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非小细胞肺癌患者MET外显子14剪接位点突变常规检测的优化

简介：最近在 NSCLC 患者中发现了影响 MNNG HOS 转化基因 (MET) 外显子 14 剪接位点的基因组改变。据报道，这些患者对 MET 酪氨酸激酶抑制剂有客观反应。因此，检测 MET 外显子 14 剪接位点突变是一项重大挑战。到目前为止，大多数这些改变是通过全外显子组测序或基于大捕获的下一代测序（NGS）面板发现的，不适合常规诊断。方法：为了提供适用于常规实践的分子检测方法，我们首先开发了一种片段长度分析，用于检测 MET 外显子 14 侧翼内含子的缺失。其次，我们设计了一个优化的靶向 NGS 面板，称为 CLAPv1，除了基因组测试中通常涵盖的主要分子靶标之外，还涵盖 MET 外显子 14 和侧翼区域。在 MET 外显子 14 突变的患者中，还测定了 MET 基因扩增、基因拷贝数和 MET 受体表达。结果：在 1514 份福尔马林固定石蜡包埋的 NSCLC 样本中，未优化的 NGS 仅允许在 0.3% 的患者中检测到 MET 外显子 14 突变，并且片段长度分析在 1.1% 的患者中检测到缺失。结合起来，用于常规分子检测的优化 CLAPv1 panel 和片段长度分析揭示了 365 名额外 NSCLC 患者中 2.2% 的 MET 外显子 14 改变。在携带 MET 外显子 14 突变的 30 名患者中有 6 名 (20%) 观察到 MET 基因扩增或高基因拷贝数。结论：