Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Medical Genetics, National Taiwan University Hospital, Taipei 100,Taiwan.
Hum Pathol. 2019 Apr;86:12-20. doi: 10.1016/j.humpath.2018.11.014. Epub 2018 Nov 24.
Mutational profiling is recommended for selecting targeted therapy and predicting prognosis of metastatic colorectal cancer (CRC). Detection of coexisting mutations within the same pathway, which are usually mutually exclusive, raises the concern for potential laboratory errors. In this retrospective study for quality assessment of a next-generation sequencing assay, we examined BRAF, KRAS, and NRAS genes within the mitogen-activated protein kinase (MAPK) pathway and the PIK3CA gene within the phosphatidylinositol 3-kinase (mTOR) pathway in 744 CRC specimens submitted to our clinical diagnostics laboratory. Although coexistence of mutations between the MAPK and mTOR pathways was observed, it rarely occurred within the MAPK pathway. Retrospective quality assessments identified false detection of coexisting activating KRAS and NRAS mutations in 1 specimen and confirmed 2 activating KRAS mutations in 2 specimens and coexisting activating KRAS and NRAS mutations in 2 specimens, but no coexisting activating RAS and BRAF mutations. There were 15 CRCs with a kinase-impaired BRAF mutation, including 3 with a coexisting activating KRAS mutation, which may have therapeutic implications. Multiregional analysis based on different histologic features demonstrated that coexisting KRAS and NRAS mutations may be present in the same or different tumor populations and showed that invasion of adenomas by synchronous adenocarcinomas of different clonal origin may result in detection of coexisting mutations within the MAPK pathway. In this study, we proposed an operating procedure for clinical validation of unexpected coexisting mutations. Further studies are warranted to elucidate the biological significance and clinical implications of coexisting mutations within the MAPK pathway.
突变分析有助于选择靶向治疗药物并预测转移性结直肠癌（CRC）的预后。在同一通路中同时检测到相互排斥的共存突变会引起对潜在实验室误差的关注。在这项评估下一代测序检测质量的回顾性研究中，我们检测了 744 例送检至我们临床诊断实验室的 CRC 标本中的 MAPK 通路中的 BRAF、KRAS 和 NRAS 基因以及 mTOR 通路中的 PIK3CA 基因。虽然在 MAPK 和 mTOR 通路之间观察到共存突变，但在 MAPK 通路中很少发生。回顾性质量评估确定了 1 例标本中存在共存的激活型 KRAS 和 NRAS 突变的假阳性检测，并在 2 例标本中证实了 2 例激活型 KRAS 突变和 2 例共存的激活型 KRAS 和 NRAS 突变，但没有共存的激活型 RAS 和 BRAF 突变。有 15 例 CRC 具有激酶失活的 BRAF 突变，其中 3 例存在共存的激活型 KRAS 突变，这可能具有治疗意义。基于不同组织学特征的多区域分析表明，KRAS 和 NRAS 共存突变可能存在于同一或不同肿瘤群体中，并表明不同克隆起源的同步腺癌侵犯腺瘤可能导致 MAPK 通路中检测到共存突变。在本研究中，我们提出了一种用于临床验证意外共存突变的操作程序。需要进一步的研究来阐明 MAPK 通路中共存突变的生物学意义和临床意义。
