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Correlation of Epidermal Growth Factor Receptor Gene Mutations in Tumor Tissue and Clinical Chemosensitivity in Patients with Advanced Non-Small Cell Lung Cancer
non-small cell lung cancer,chemotherapy,epidermal growth factor receptor,gene mutation,
|Publication Year :||2006|
|Abstract:||根據目前的研究結果，表皮生長因子受體 (epidermal growth factor receptor) 基因突變與酪胺酸激酶抑制劑 (tyrosine kinase inhibitor) 的臨床反應具有關聯性，回顧性分析顯示腫瘤細胞表皮生長因子受體基因突變可作為酪胺酸激酶抑制劑治療晚期非小細胞肺癌之腫瘤反應較佳、生存期較長的獨立預後指標。而亞洲人非小細胞肺癌發生腫瘤組織表皮生長因子受體基因突變約30~42%，遠高於高加索人。但表皮生長因子受體基因突變對於化學治療的臨床反應與預後的影響卻是不清楚的。本試驗即針對使用化學治療為第一及第二線的晚期非小細胞肺癌的患者，探討其腫瘤組織部位的表皮生長因子受體的突變與病患臨床治療效果的關聯性研究。
本試驗從台大醫院腫瘤醫學部所進行的非小細胞肺癌臨床試驗中，選入86位有腫瘤組織的病患，回顧性分析其臨床資料，同時進行腫瘤組織表皮生長因子受體基因表現段18至21 (exon 18~21) 定序分析。結果：34.9%的病患腫瘤組織具有表皮生長因子受體基因突變，44.2%病患經化學治療後達到部份腫瘤緩解。突變發生的比例：腺癌患者高於非腺癌患者 (各為40.3%, 13.3%, p=.05)，女性稍高於男性(各為39.4%, 32.1%, p=.49)、和不曾抽煙、目前抽煙和過去抽煙者比例各為34.9%, 25.9%和50.0% (p=.28)。突變型態以表現段21 (exon 21) L858R置換突變者最多，佔53.3%，其次表現段19 (exon 19) 骨架E746~A750左右部位缺失突變佔26.7%。突變者對化學治療的緩解率為40%，而無突變者對化學治療的緩解率為46.4%；突變者對化學治療的疾病惡化時間中位數為4.9月 (95%信賴區間 3.0~7.2月)、存活期中位數19.0 月 (95%信賴區間 14.7~26.1月)，而無突變者對化學治療的疾病惡化時間中位數為6.9月 (95%信賴區間 6.2~8.2月)、存活期中位數22.6 月 (95%信賴區間 18.9~24.6月)。不論單變項或多變項分析皆顯現表皮生長因子受體基因突變與化學治療的效果不具有關聯性。
本試驗結果與其他相關研究做比較，與韓國人Lee等人做的試驗結果一致，但與Bell和Eberhard 等人分別在geftinib和erlotinib的 INTACT 和TRIBUTE試驗所做的研究相比有差別，Bell等人指出表皮生長因子受體基因突變者與無突變者，其存活期中位數統計上有差別 (各為19.4月比9.2月)，但此試驗東亞人僅佔6.9%；相較本試驗結果不論突變者或無突變者，其存活期中位數都較長 (各為19.0月比22.6月)。因此本試驗結果推知腫瘤組織表皮生長因子受體基因突變可能不適合做為東亞人化學治療療效之預測指標。
Based on current available evidences, the mutations in tyrosine kinase domain of epidermal growth factor receptor (EGFR) was significantly associated with clinical responsiveness to tyrosine kinase inhibitors (TKIs) in patients with advanced non-small cell lung cancer (NSCLC). Retrospective studies showed that EGFR tyrosine kinase mutation in tumor specimen was as an independent predictive factor of clinical outcomes for TKI treated patients. Patients with mutations would have better clinical response to TKI and longer overall survival in comparison with wild-type patients. The mutation rate was 30 to 42% in Asian patients, higher than Caucasian patients. However, the relationship between clinical responsiveness to chemotherapy and its impact on survival and EGFR mutations was unclear in patients with advanced NSCLC. In this study, we investigated the influence of EGFR mutations in tumor specimens on the clinical outcomes of advanced NSCLC patients who received chemotherapy as 1st or 2nd line treatment.
In total, 86 patients with available tumor specimens were selected from these clinical trials of NSCLC, which conducted at the Department of Oncology, National Taiwan University Hospital. Tumor sequencing in exon 18 through 21 of EGFR, and retrospective collection of clinical data of patients were performed. RESULTS: 34.9% of patients had EGFR mutations. 44.2% of patients had a partial response to chemotherapy. The mutations in subgroups – more frequently found in patients with adenocarcinoma than patients with other histologic types (40.3% vs 13.3%, p=.05), in female than male (39.4% vs 32.1%, p=.49). The mutation rates were 34.9%, 25.9%, 50.0%, respectively in patients who had never smoked, currently smoked, and formerly smoked. The L858R substitution mutation in exon 21 was the most common mutation in 53.3% of all mutations. The in-frame deletions located around E746-A750 in exon 19 were second frequent in 26.7% of all mutations. The response rate to chemotherapy was 40.0% in EGFR mutation-positive subgroup compared to 46.4% in EGFR mutation-negative subgroup (p=.57). The median time-to-progression (TTP) and overall survival (OS) for the patients with EGFR mutations were 4.9 months (95% CI, 3.0-7.2 months), and 19.0 months (95% CI, 14.7-26.1 months), respectively, compared to the median TTP and OS of patients with wild-type (6.9 months, 95% CI, 6.2-8.2 months in TTP; and 22.6 months, 95% CI, 18.9-24.6 months in OS), there were no statistically significant differences in TTP and OS. Therefore, clinical responsiveness to chemotherapy was not associated with EGFR mutations in advanced NSCLC patients.
In comparison with other related researches, our results were consistent with recent report published by Lee et al, but different from the results of researches (Bell and Eberhard et al) in INTACT and TRIBUTE studies. Bell et al showed that EGFR mutated patients treated with chemotherapy alone had a better overall survival compared with mutation negative patients (median OS, 19.4 months vs 9.2 months), but there were only 6.9% of East Asian patients in INTACT study. In our study, both mutated and wild-type advanced NSCLC patients had long survival (median OS, 19.6 and 22.6 months, respectively). Therefore, it was possible that EGFR mutational status was not a good predictive factor in East Asian patients with advanced NSCLC.
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