肺腺癌患者表皮生长因子受体（EGFR）酪氨酸激酶抑制剂获得性耐药前后EGFR基因状态变化情况探讨

Epidermal growth factor receptor （EGFR） mutation status before and after acquired resistance to EGFR tyrosine kinase inhibitors in patients with lung adenocarcinoma

目的应用突变扩增阻滞系统（ARMS）法检测肺腺癌患者表皮生长因子受体（EGFR）酪氨酸激酶抑制剂（TKI）获得性耐药前后EGFR基因突变情况，并用微滴式数字PCR系统（ddPCR）对其进一步验证，探讨获得性耐药前后EGFR基因状态的变化情况，并结合这些变化情况讨论导致这些EGFR基因改变的可能原因。方法收集EGFR-TKI治疗前以及EGFR-TKI获得性耐药后均进行取材的肺腺癌患者20例，其中EGFR-TKI治疗前ARMS法EGFR基因检测有5例为野生型，15例为EGFR-TKI敏感性突变位点L858R和19-del，疾病进展时间4-18个月不等，男性13例，女性7例。采用ARMS法进行EGFR基因第18、19、20、21号外显子突变检测，ddPCR对其进一步验证。结果20例肺腺癌患者中，5例EGFR-TKI治疗前EGFR基因野生型患者，在发生EGFR-TKI获得性耐药后EGFR基因同样为野生型。15例治疗前EGFR-TKI敏感性突变患者中，获得性耐药后有10例EGFR基因发生了改变，其中T790M突变的有8例，1例患者EGFR基因由原来的L858R变为G719X＋S768I双突变，还有1例患者EGFR基因由原来的19-del变为野生型。其次，EGFR-TKI获得性耐药后ARMS法有2例发生T790M突变的胸水细胞块未检出。结论EGFR基因T790M突变是导致获得性耐药的主要突变类型；对于EGFR基因阴性患者，EGFR-TKI获得性耐药并没有使其EGFR基因发生改变；对于EGFR-TKI敏感性的EGFR突变患者，EGFR-TKI获得性耐药可能会使EGFR药敏突变位点发生丢失或改变。

Objective To investigate epidermal growth factor receptor （EGFR） mutation status in lung adenocarcinomas before and after acquiring resistance to EGFR tyrosine kinase inhibitors （TKIs） using ARMS method followed by further verification using droplet digital PCR technique. Methods Twenty qualified patients were included, among them 13 were male and 7 were female patients. Before EGFR-TKIs treatment, 5 patients were EGFR wild-type by ARMS, and the other 15 patients had L858R or 19-del point mutations. The time to progression varied from 4 to 18 months. Mutation of exons 18, 19, 20 and 21 were detected by ARMS, and were verified by droplet digital PCR system method. Results EGFR wild-type status was unchanged before and after acquired resistance to EGFR-TKIs in 5 lung adenocarcinoma patients. Alteration of EGFR mutation status occurred in 10 of the 15 patients with pre-treatment L858R or 19-del mutations. Among them, T790M mutation was found in 8 patients, L858R became GT19X plus S768I mutation in one patient, and 19-del converted into wild-type in one other patient. Conclusions T790M mutation is the primary type of EGFR mutation in lung adenocarcinomas with acquired resistance to EGFR- TKIs therapy. Acquired resistance to EGFR-TKIs dose not lead to the alteration of EGFR status in pre- treatment EGFR wild-type patients, but can alter EGFR mutation status in pre-treatment EGFR mutantpatients.