Gu Jincui, Zang Wanchun, Liu Bing, Li Lei, Huang Lixia, Li Shaoli, Rao Guanhua, Yu Yang, Zhou Yanbin
Department of Respiratory Medicine, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China.
Novogene Bioinformatics Institute, Beijing, China.
Oncotarget. 2017 Jun 29;8(40):67810-67820. doi: 10.18632/oncotarget.18866. eCollection 2017 Sep 15.
Emerging evidence has indicated that circulating tumor DNA (ctDNA) from plasma could be used to analyze EGFR mutation status for NSCLC patients; however, due to the low level of ctDNA in plasma, highly sensitive approaches are required to detect low frequency mutations. In addition, the cutoff for the mutation abundance that can be detected in tumor tissue but cannot be detected in matched ctDNA is still unknown. To assess a highly sensitive method, we evaluated the use of digital PCR in the detection of EGFR mutations in tumor tissue from 47 advanced lung adenocarcinoma patients through comparison with NGS and ARMS. We determined the degree of concordance between tumor tissue DNA and paired ctDNA and analyzed the mutation abundance relationship between them. Digital PCR and Proton had a high sensitivity (96.00% vs. 100%) compared with that of ARMS in the detection of mutations in tumor tissue. Digital PCR outperformed Proton in identifying more low abundance mutations. The ctDNA detection rate of digital PCR was 87.50% in paired tumor tissue with a mutation abundance above 5% and 7.59% in paired tumor tissue with a mutation abundance below 5%. When the DNA mutation abundance of tumor tissue was above 3.81%, it could identify mutations in paired ctDNA with a high sensitivity. Digital PCR will help identify alternative methods for detecting low abundance mutations in tumor tissue DNA and plasma ctDNA.
新出现的证据表明，血浆中的循环肿瘤DNA（ctDNA）可用于分析非小细胞肺癌（NSCLC）患者的表皮生长因子受体（EGFR）突变状态；然而，由于血浆中ctDNA水平较低，需要高灵敏度的方法来检测低频突变。此外，肿瘤组织中可检测到但匹配的ctDNA中无法检测到的突变丰度阈值仍然未知。为了评估一种高灵敏度方法，我们通过与二代测序（NGS）和扩增阻滞突变系统（ARMS）比较，评估了数字PCR在检测47例晚期肺腺癌患者肿瘤组织中EGFR突变的应用。我们确定了肿瘤组织DNA与配对ctDNA之间的一致性程度，并分析了它们之间的突变丰度关系。在检测肿瘤组织中的突变时，与ARMS相比，数字PCR和Proton具有较高的灵敏度（分别为96.00%和100%）。在识别更多低丰度突变方面，数字PCR优于Proton。在配对的肿瘤组织中，当突变丰度高于5%时，数字PCR的ctDNA检测率为87.50%；当突变丰度低于5%时，检测率为7.59%。当肿瘤组织的DNA突变丰度高于3.81%时，它可以高灵敏度地识别配对ctDNA中的突变。数字PCR将有助于确定检测肿瘤组织DNA和血浆ctDNA中低丰度突变的替代方法。
