小细胞肺癌NTRK基因融合/变异检测分析

Gene fusion and mutation of neurotrophic factor receptor tyrosine kinase in small cell lung cancer

目的 探讨肺小细胞癌(small cell lung cancer, SCLC)中神经营养因子受体酪氨酸激酶(NTRK)的基因融合及基因变异情况。方法 回顾性收集北京协和医院2008—2021年间SCLC病例组织标本58例,并收集相应临床病理资料;采用免疫组化(immunohistochemistry, IHC)染色方法检测NTRK融合蛋白表达情况,对经IHC染色鉴定为NTRK阳性的病例,进一步采用荧光原位杂交(FISH)方法进行验证。此外,通过包含638基因的靶向测序检测58例标本的NTRK突变及融合变异。结果 本研究中共纳入58例SCLC病例。IHC检测结果提示6例(10.3%)样本NTRK阳性表达,但FISH及靶向测序检均未在此队列中发现NTRK融合基因;靶向测序结果提示11例样本(11/58,19.0%)检出12个NTRK突变,其中1例样本为NTRK1与NTRK3共突变,其余为单一NTRK突变,NTRK3突变6例(10.3%)、NTRK1突变3例(5.1%)、NTRK2突变1例(1.7%);2例伴有NTRK突变病例为IHC阳性表达。结论 本组SCLC缺乏NTRK基因融合,NTRK基因突变率为19%,通过IHC检测方法在SCLC中筛查NTRK融合蛋白表达具有较高的假阳性率,需要采用其他检测平台进行复验。

Objective To explore the frequency of neurotrophic factor receptor tyrosine kinase( NTRK) gene fusion and gene mutation in small cell lung cancer( SCLC). Methods Tissue samples of 58 cases of SCLC from Peking Union Medical College Hospital between 2008 and 2021 were retrospectively collected,as well as the clinicopathological and follow-up data. Immunohistochemistry( IHC) staining was used as the screening method. The cases assessed as positive for NTRK by IHC staining were further validated by fluorescence in situ hybridization( FISH). In addition,all the 58 samples were detected by targeted sequencing using the panel covering 638 genes. Results A total of 58 cases of SCLC were included in this study. NTRK expression was found in 6 patients( 10. 3%) using IHC. No fusion gene was detected via either FISH or next-generation sequencing( NGS). Twelve NTRK mutations were identified from 11 patients,from which one patient harbored mutations of both NTRK1 and NTRK3 and NTRK3 harbored the highest mutation frequency( 10. 3%),followed by NTRK1( 5. 2%),and NTRK2( 1. 7%). Two samples with NTRK mutations had positive IHC expression. Conclusion SCLC samples lack NTRK gene fusion in our cohort. Detecting NTRK gene fusion via IHC has a quite high false positive rate,and the result requires further validation through other method.