EGFR第一内含子(CA)n双核苷酸重复多态性和基因突变与肺癌分子靶向治疗的反应

Intron 1 (CA)n dinucleotide repeat polymorphism and mutations of epidermal growth factor receptor and responsiveness of molecular targeted therapy in lung cancer

目的:对肺癌组织EGFR基因突变和第一内含子(CA)n双核苷酸重复多态性与分子靶向药物治疗反应相关性进行初步研究。方法:用基因测序的方法检测了观察组共116例肺癌体细胞标本;对照组20例肺癌患者血液标本。对全部标本的EGFR基因18、19、21外显子,以及其中48例第一内含子(CA)n重复序列进行基因测序分析并随访了45例肺癌患者分子靶向药物(易瑞沙)治疗情况。结果:观察组116例标本中共发现20例(17.25%)EGFR基因突变,其中17例为外显子突变,3例为内含子杂合突变。对照组20例肺癌患者血液标本均未发现突变。肺腺癌的突变率为21.62%,比鳞癌(8.33%)、其它类型癌(11.11%)略高,但无统计学差异。EGFR基因突变在女性患者中(7/36,19.45%)所占比例比男性患者(13/80,16.25%)略高,但无统计学差异。观察组中,随访外显子突变患者服用易瑞沙的有效率(62.5%)显著高于未突变者(0%)(P<0.01),疾病控制率(100%)高于未突变组(44.4%)(P<0.05)。外显子突变患者服用易瑞沙治疗的疾病控制率(100%)高于未服用者(40%)(P<0.05)。内含子杂合的3例中有2例服用易瑞沙,有效率为0%,疾病控制率50%。观察组与对照组有23例(CA)n短重复(CA≤16)(47.9%),25例(CA)n长重复(CA>16)(52.1%)。EGFR第一内含子(CA)n重复片段长短与基因突变无明显相关,OR(OddsRatio)(2。观察组中,16例突变患者与18例未突变患者(CA)n重复片段的长短与分子靶向药物治疗有效率、疾病控制率均无统计学差异(P>0.05)。结论:EGFR基因突变组患者分子靶向药物治疗有效率(62.5%vs0)、疾病控制率(100%vs44.4%)要明显优于无突变组。在肺癌中,EGFR基因体细胞突变是决定表皮生长因子受体酪氨酸激酶抑制剂敏感性的最重要的因素。(CA)n重复片段长短与EGFR基因突变无明显相关。分析突变因素关联的(CA)n短重复患者与(CA)n长重复患者的分子靶向药物治疗有效率、疾病控制率无统计学差异。由于部分未突变肺癌患者使用易瑞沙出现一定的疾病控制率,有关分子靶向药物疗效与(CA)n重复的关系有待进一步单因素研究。

Objective： （CA） n repeat polymorphism in intron 1 and EGFR mutations were analyzed for its association with molecular targeted therapy responsiveness in lung cancer. Methods：Both of observed group consisted of 116 somatic specimens of lung cancer and control group consisted of 20 peripheral blood samples were analyzed by direct DNA sequencing. Epidermal growth factor receptor mutations at exons 18,19,21 were analyzed for overall 136 specimens. CA repeat polymorphisms in intron 1 of EGFR from 48 specimens were also analyzed by direct sequencing. 45 lung cancer patients were followed up for their treatment outcome of molecular targeted drug （ EGFR Tyrosine kinase inhibitors） molecular targeted drug. In addition, we analyzed （CA） n dinucleotide repeat polymorphism in intron 1 of EGFR followed EGFR mutations data in exons 18,19,21 for their association with clinical outcome in lung cancer patients treated with molecular targeted drug. Results：EGFR mutations were identified in 20 patients （ 17.25% ） out of 116 somatic specimens including 17 mutations in extron domain and 3 heterozygosis in intron domain. None mutation was found in 20 peripheral blood samples in control group. Although the mutant frequency in the adenocarcinoma （21.62%） was a little higher than in the squamous cell carcinoma （ 8.33% ） and in other histological types （ 11.11% ） of lung cancer, there was no significant difference between them. The rate of mutations in female patients （7/36,19.45 % ） was a little higher than those in male patients （13/80,16.25 % ）, but there was also no significant difference between them. Response rate to EGFR TKIs was significantly higher in the patients with EGFR mutations （62.5%） than those without mutation （0%） in observed groups （P 〈 0.01 ）. Disease control rate to EGFR TKIs was significantly higher in the patients with EGFR mutations （100%） than those without mutation （44.4%） in observed group （P 〈 0.05 ）. In patients harboring EGFR mutations , disease control rate to patients treated with EGFR TKls （ 100% ） was significantly higher than those who never treated with it （40%） （ P 〈 0.05）. Two of three patients with heterozygosis in intron domain treated with EGFR TKls, the response rate was 0% and the disease control rate was 1/2. The frequency distribution of EGFR intren 1 （CA）n repeat in 48 cases was 23 （47.9%）low （CA）n repeat （ CA ≤ 16） and 25 （52.1% ） high ones （ CA 〉 16） in cases and controls. There was no statistical correlation between the length of （CA）n repeat in intron 1 and gene mutations of EGFR （P 〉0.05, OR 〈 2）. There was no significant difference in response rate and disease control rate of EGFR TKIs treatment between low and high （CA） n repeat numbers both in 16 patients with mutations and 18 patients without mutations in observed group（P 〉0.05）. Conclusion：Response rate （62.5 % vs 0）and disease control rate （100% vs 44.4% ）to EGFR TKIs treatment were significantly higher in the patients with EGFR mutations than who without it . Our results once again showed that somatic mutations of EGFR was a major determinant of EGFR TKIs response in lung cancer. There was no statistical correla- tion between the length of （CA） n repeat in intron 1 and mutations of EGFR. There was no significant difference in response rate and disease control rate of EGFR TKIs treatment between low （CA） n repeat patients and high repeat ones, cohsidering of the mutant factor. As the presents of certain disease control rate in the non - mutation lung cancer patients treated with EGFR TKls, the relationship between the length of （CA）n repeat and molecular targeted drug sensitivity need to be studied furthermore.