Somatic mutations of the epidermal growth factor receptor and non-small-cell lung cancer

Frequent overexpression of epidermal growth factor receptor (EGFR) in non-small-cell lung cancer (NSCLC) makes EGFR a new therapeutic target. Two specific EGFR tyrosine kinase inhibitors, gefitinib (ZD1839, Iressa) and erlotinib (OSI-774, Tarceva), have been developed and approved by the US Food and Drug Administration for second-line and third-line treatment of advanced NSCLC. Clinical trials have shown considerable variability in the response rate between different patients with NSCLC, which led to the discovery of somatic EGFR-activating mutations. This brief review summarises the discovery and functional consequences of the mutations, their clinicopathological features and significant implications in the treatment and prognosis of NSCLC.     

Cytomorphological correlates of epidermal growth factor receptor mutations in lung carcinoma

The initial diagnosis of lung carcinoma is frequently made by fine-needle aspiration biopsy. Novel therapeutic strategies of this disease include tyrosine kinase inhibitors (TKI), such as gefitinib (Iressa) or erlotinib (Tarceva), which target the kinase domain of epidermal growth factor receptor (EGFR). Somatic mutations of this region have been shown to predict a therapeutic response of lung carcinomas to TKI. EGFR mutations have been described in adenocarcinomas of the lung, especially the bronchioloalveolar subtype, which has both cytopathologic and histopathologic definitions. This study investigates whether tumors with EGFR mutations display a characteristic phenotype on fine-needle aspiration biopsy. We identified 37 fine-needle aspiration biopsy of lung masses on which molecular analysis for EGFR mutations was available. Molecular analysis was performed on DNA isolated from formalin-fixed, paraffin-embedded, or frozen tissue from the corresponding core biopsies/cell blocks or resection specimens followed by PCR with primers for the tyrosine kinase region exons 18-24 and nucleotide sequence analysis by gel electrophoresis. Two observers who were blinded to the mutational data assessed several cytomorphological parameters. A semiquantitative analysis included predominant tissue pattern (flat or overlapping), nuclear features (nucleoli, intranuclear inclusions, grooves), cytoplasmic qualities, and extracellular material. All cases were adenocarcinomas primary in the lung. Thirteen cases showed EGFR mutations in exons 18, 19, 20, or 21 of the tyrosine kinase domain. The 24 cases negative for the relevant mutation served as the control group. Tumors with EGFR mutations were statistically more likely to demonstrate a predominantly flat, monolayer architecture (P=0.04) with nuclear inclusions (P=0.014) and the absence of macronucleoli (P=0.001). The predominance of flat monolayers in conjunction with the absence of extracellular mucin and macronucleoli indicated the presence of EGFR mutations with a positive predictive value of 69% and a negative predictive value of 92%. All four cases with extracellular mucin were negative for the examined mutations. Some of the traditional cytomorphological features of bronchioloalveolar carcinoma, i.e., flat monolayers, intranuclear inclusions, and the absence of macronucleoli, statistically correlated with the presence of mutations within the tyrosine kinase region of EGFR. Cytomorphological features could serve as an adjunctive predictive marker of response to TKIs and possibly to other new therapies in development.     

非小细胞肺癌表皮生长因子受体及其靶向治疗研究进展

非小细胞肺癌是目前全球最常见的恶性肿瘤之一,尽管手术治疗和化学治疗技术不断发展,但非小细胞肺癌患者生存率却没有明显改变。表皮生长因子受体 (epidermal growth factor receptor,EGFR)是一种受体型酪氨酸激酶,在非小细胞肺癌中有过表达,且与非小细胞肺癌的发生、发展、侵袭等方面密切相关,是最有前途的特异性肿瘤靶向治疗分子之一。此外,在非小细胞肺癌中常检测到EGFR基因突变,尤其是在女性、非吸烟者、肺腺癌和亚洲人种中,这与非小细胞肺癌患者对吉非替尼治疗的敏感性密切相关。     

肺腺癌表皮生长因子受体基因突变与CT征象的相关性

目的 探讨肺腺癌CT征象对表皮生长因子受体（EGFR）基因突变的预测价值.方法 回顾性分析200例经手术切除的肺腺癌患者的CT资料,统计其术后病理标本的EGFR基因检测结果,分析两者之间的相关性.结果 单因素分析显示非吸烟、女性患者、CT征象中的含气支气管征及较小肿瘤直径与肺腺癌EGFR基因突变存在明显相关性,突变组与野生组的差异均有统计学意义（P＜0.05）,EGFR基因突变组肺腺癌磨玻璃密度（GGO）发生率高于野生组,但差异无统计学意义（P＞0.05）,其他临床及CT征象如年龄、分叶征、毛刺征、钙化、空洞、胸膜凹陷征均与EGFR基因突变无关,突变组与野生组的差异均无统计学意义（P＞0.05）.Logistics回归分析显示非吸烟及含气支气管征与EGFR基因突变明显相关,突变组与野生组的差异均有统计学意义（P＜0.05）,而性别及肿物大小与EGFR基因突变与否无明显相关性,突变组与野生组的差异均无统计学意义（P＞0.05）.结论 非吸烟、含气支气管征可作为肺腺癌EGFR基因突变的预测因素.     

非小细胞肺癌中表皮生长因子受体基因突变直接测序分析及其与临床病理特征的相关性

目的回顾性分析非小细胞肺癌(NSCLC)中采用直接测序法检测的表皮生长因子受体(EGFR)基因突变率、突变分布特征及其与临床病理的相关性。方法收集NSCLC共443例,其中包括手术切除样本299例、粗针穿刺活检标本59例、细针穿刺和胸腔积液细胞学样本85例。所有样本均通过石蜡包埋、切片后确定肿瘤细胞含量,显微切割富集肿瘤细胞后采用聚合酶链反应-直接测序法检测EGFR基因酪氨酸激酶编码区第18至21号外显子的突变。结果(1)在443例NSCLC标本中共检出EGFR基因突变193个,发生在189例患者中(42.7％);EGFR基因第18至21号外显子的突变率分别为2.0％( 4/193)、48.7％ (94/193)、6.7％ (13/193)和42.5％ (82/193);(2)EGFR基因总突变率与年龄无显著相关性,但在年龄大于中位年龄（57岁）的患者中第21号外显子的突变率(50.9％,54/106)高于年龄小于或等于中位年龄者(32.2％,28/87;P＜0.01);(3)女性患者中EGFR基因突变率(53.5％,107/200)高于男性患者突变率(33.7％,82/243;P ＜0.01);(4)腺癌中的突变率(46.5％,161/346)高于鳞癌(13.3％,4/30;P＜0.01)和低分化癌者(24.1％,7/29;P＜0.05),而与腺鳞癌(7/13)差异无统计学意义(P＞0.05);(5)在手术切除、粗针穿刺活检以及细针穿刺和胸腔积液细胞学样本中EGFR突变检出率有逐渐下降的趋势,分别为49.5％( 148/299)、35.6％ (21/59)和23.5％ (20/85),其中细针穿刺和胸腔积液的细胞学样本中的检出率较手术标本中的检出率为低(P＜0.01)。结论直接测序法是检测NSCLC中EGFR基因突变的有效方法,特别对未知突变类型的检出具有优势;NSCLC中EGFR基因突变在女性和腺癌中多见,以第19号外显子的缺失突变和第21号外显子的点突变为主;EGFR基因突变分布特征可能与年龄有一定关系;EGFR基因突变检出率与样本类型密切相关,活检组织及细胞学样本是检测EGFR基因突变的有用材料,但可能会漏检部分患者中EGFR基因的突变。     

表皮生长因子受体基因突变与非小细胞肺癌的基因靶点药物治疗

进入21世纪伊始,肿瘤治疗的革命正面临着基因分子靶点药物的洗礼,2005年5月美国临床肿瘤年会（ASCO）上首日论文分别是“癌症分子靶向治疗”和讲座“靶向人类癌症的表皮生长因子受体（EGFR）途径”。随着国外分子靶点药物Iressa（gefitinib,ZD1839）两项单药治疗非小细胞肺癌的Ⅱ期临床随机对照研究（IDEAL1和IDEAL2）及后续的扩大研究,证实其有很好的疗效且副作用很小,这引起了国内外医学界的瞩目。     

Frequent mutations in the neurotrophic tyrosine receptor kinase gene family in large cell neuroendocrine carcinoma of the lung

The neurotrophic tyrosine receptor kinase (NTRK) family is potentially implicated in tumorigenesis and progression of several neoplastic diseases, including lung cancer. We investigated a large number of pulmonary neuroendocrine tumors (PNETs) and non-small cell lung carcinomas (NSCLCs) without morphological evidence of neuroendocrine differentiation for mutations in the NTRK gene family. A total of 538 primary lung carcinomas, including 17 typical carcinoids (TCs), 10 atypical carcinoids (ACs), 39 small cell lung carcinomas (SCLCs), 29 large cell neuroendocrine carcinomas (LCNECs), and 443 NSCLCs were evaluated by single-strand conformation polymorphism (SSCP) and sequencing of the tyrosine kinase domain (TKD) of NTRK1, NTRK2, and NTRK3. The NTRK1 gene was never found to be mutated. A total of 10 somatic mutations were detected in NTRK2 and NTRK3, mostly located in the activating and catalytic loops. NTRK mutations were seen in 9 (10%) out of 95 PNETs but in 0 out of 443 NSCLCs investigated. No mutations were observed in TCs, ACs, and SCLCs. Interestingly, all the mutations were restricted to the LCNEC histotype, in which they accounted for 31% of cases. A mutational analysis, performed after microdissection of LCNECs combined with adenocarcinoma (ADC), showed that only neuroendocrine areas were positive, suggesting that NTRK mutations are involved in the genesis of the neuroendocrine component of combined LCNECs. Our data indicate that somatic mutations in the TKD of NTRK genes are frequent in LCNECs. Such mutational events could represent an important step in the cancerogenesis of these tumors and may have potential implications for the selection of patients for targeted therapy.     

Specific inhibitors of platelet-derived growth factor or epidermal growth factor receptor tyrosine kinase reduce pulmonary fibrosis in rats.

The proliferation of myofibroblasts is a central feature of pulmonary fibrosis. In this study we have used tyrosine kinase inhibitors of the tyrphostin class to specifically block autophosphorylation of the platelet-derived growth factor receptor (PDGF-R) or epidermal growth factor receptor (EGF-R). AG1296 specifically inhibited autophosphorylation of PDGF-R and blocked PDGF-stimulated [3H]thymidine uptake by rat lung myofibroblasts in vitro. AG1478 was demonstrated as a selective blocker of EGF-R autophosphorylation and inhibited EGF-stimulated DNA synthesis in vitro. In a rat model of pulmonary fibrosis caused by intratracheal instillation of vanadium pentoxide (V2O5), intraperitoneal delivery of 50 mg/kg AG1296 or AG1478 in dimethylsulfoxide 1 hour before V2O5 instillation and again 2 days after instillation reduced the number of epithelial and mesenchymal cells incorporating bromodeoxyuridine (Brdu) by approximately 50% at 3 and 6 days after instillation. V2O5 instillation increased lung hydroxyproline fivefold 15 days after instillation, and AG1296 was more than 90% effective in preventing the increase in hydroxyproline, whereas AG1478 caused a 50% to 60% decrease in V2O5-stimulated hydroxyproline accumulation. These data provide evidence that PDGF and EGF receptor ligands are potent mitogens for collagen-producing mesenchymal cells during pulmonary fibrogenesis, and targeting tyrosine kinase receptors could offer a strategy for the treatment of fibrotic lung diseases.     

非小细胞肺癌表皮生长因子受体基因突变检测及其临床意义

目的探讨非小细胞肺癌(NSCLC)表皮生长因子受体(EGFR)基因突变检测技术及其临床意义。方法采用聚合酶链反应(PCR)扩增DNA直接测序法检测192例NSCLC的EGFR基因第18 ～21号外显子突变情况,并结合临床病理指标分析其意义。结果192例非小细胞肺癌中64例存在EGFR酪氨酸激酶结合域的基因突变(33.3％),其中第19号外显子缺失突变率为60.9％( 39/64),第21号外显子替代突变率为39.1％ (25/64),第18和20号外显子未发现突变。在伴有细支气管肺泡癌分化特征的肺腺癌中EGFR基因突变率为58.5％( 24/41),显著高于普通腺癌(37.9％,33/87)、鳞癌(7.5％,4/53)、大细胞癌(1/5)和腺鳞癌(2/6),P＜0.05;女性(51.9％,40/77)显著高于男性(20.9％,24/115),P＜0.01;不吸烟者(50.0％,57/114)显著高于吸烟者(9.0％,7/78),P＜0.01。结论PCR扩增DNA直接测序法检测NSCLC的EGFR基因突变技术稳定、可靠,为临床开展NSCLC靶向治疗提供了依据。     

Clinical and prognostic importance of expression of epidermal growth factor receptors in non-small-cell lung carcinoma

Radioligand assay demonstrated that in patients with non-small-cell lung cancer, expression of epidermal growth factor receptors in the tumor is higher than in non-tumor tissue. Expression of epidermal growth factor receptors in tumor and non-tumor lung tissue does not correlate with the stage and metastasizing of the disease and tumor histology. It is also shown that expression of epidermal growth factor receptors in tumor and non-tumor tissue is associated with lower survival rate. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol 127, No. 4, pp. 446–449, April, 1999     

非小细胞肺癌中EGFR突变与临床病理特征的关系

目的 观察非小细胞肺癌(non-small cell lung cancers,NSCLC)患者肿瘤组织中表皮生长因子受体(epidermal growth factor receptor,EGFR)19号和21号外显子突变情况,探讨其与临床病理特征的关系.方法 应用显微切割技术及扩增阻滞突变系统检测108例石蜡包埋NSCLC组织中EGFR基因第19号和21号外显子突变情况.结果 108例NSCLC患者中,EGFR基因突变率为36.1%(39例),其中19号外显子突变率为13.0%(14例),21号外显子突变率为23.1%(25例);EGFR基因突变的患者多为不吸烟、肿瘤直径较小(<3 cm)、腺癌、无远处转移及临床分期较早(P<0.05),与患者性别、病理分级及淋巴结转移无显著相关性(P>0.05);所有鳞癌标本中均无EGFR基因突变;EGFR突变的患者应用吉非替尼靶向治疗后原发肿瘤和脑转移灶明显缩小.结论 EGFR基因19号和21号外显子突变作为有效的NSCLC靶向治疗的临床筛选指标,很可能参与NSCLC的发生、发展,与相关的临床病理指标结合可为NSCLC的靶向治疗提供更可靠的依据.     

非小细胞肺癌表皮生长因子受体基因突变与临床病理特征的关系

目的探讨非小细胞肺癌(NSCLC)表皮生长因子受体(EGFR)基因突变的临床病理学意义。方法应用即时荧光定量聚合酶链反应(PCR)法检测1444例NSCLC患者肺癌组织中EGFR基因第19号和21号外显子突变状况,分析EGFR基因突变与年龄、性别、吸烟状况、组织学分级及临床分期之间的关系。结果1410例成功分型的NSCLC肿瘤组织中401例存在EGFR突变,突变检出率为27.8％,其中193例第19号外显子发生缺失突变,208例第21号外显子发生替代突变。EGFR突变更常见于腺癌、不吸烟或女性患者[突变率分别为33.5％ (367/1094)]、37.6％( 321/853)及43.2％ (225/521)。细支气管肺泡癌及伴细支气管肺泡癌分化特征的腺癌突变率显著高于普通腺癌[突变率分别为61.3％( 19/31)、48.0％( 12/25)及32.4％ (336/1038)]。随着吸烟暴露水平的增加,EGFR突变率呈下降趋势;女性、不吸烟、腺癌为EGFR基因突变状况的独立影响因素。结论NSCLC患者女性、不吸烟、腺癌患者突变率较高。即时荧光定量PCR技术可快速、敏感、准确地检测EGFR基因突变。     

Epidermal growth factor receptor gene mutations in atypical adenomatous hyperplasias of the lung.

Activating epidermal growth factor receptor (EGFR) gene mutations are frequently detected in lung adenocarcinomas, especially adenocarcinomas with a nonmucinous bronchioloalveolar carcinoma component. EGFR-mutated lung adenocarcinomas respond well to EGFR tyrosine kinase inhibitors. We previously found that most (88%) pure nonmucinous bronchioloalveolar carcinomas (adenocarcinoma in situ) already harbor EGFR mutations, indicating that the mutations are an early genetic event in the pathogenesis. We examined 54 atypical adenomatous hyperplasias, precursor lesions of lung adenocarcinomas, obtained from 28 Japanese patients for the hotspot mutations of EGFR exons 19 and 21 and K-ras codon 12. EGFR mutations were observed in 17 of the 54 (32%) atypical adenomatous hyperplasias examined: Ten and seven atypical adenomatous hyperplasias had deletion mutations at exon 19 or point mutations (L858R) at exon 21, respectively. We did not observe apparent histological differences between atypical adenomatous hyperplasias with and without EGFR mutations. K-ras mutation (G12S) was detected in only one atypical adenomatous hyperplasia. As EGFR mutational frequency of atypical adenomatous hyperplasias was much lower than that of nonmucinous bronchioloalveolar carcinomas, we surmise that EGFR-mutated atypical adenomatous hyperplasias, but not atypical adenomatous hyperplasias with wild-type EGFR, are likely to progress to nonmucinous bronchioloalveolar carcinomas.     

Expression of epidermal growth factor receptor in breast carcinoma.

A series of 90 patients with primary operable breast cancer and with up to 36 months of follow up were investigated for expression of epidermal growth factor receptor (EGFR) in their tumours by immunocytochemical staining with the monoclonal antibody EGFR 1. Tumour samples were snap frozen in liquid nitrogen immediately after resection and subsequently stained using a standard indirect immunocytochemical method. Tumour staining was assessed by two observers and scored on a four point scale (0-3). Thirteen (14%) tumours showed positive immunoreactivity. A strong correlation between distinct EGFR expression and short disease free interval was observed. Significant correlations were also shown with oestrogen and progesterone receptor expression and tumour nuclear size. No significant association was found with tumour size, lymph node stage, and histological grade. The association with disease free interval remained significant in multivariate analysis.     

Epidermal growth factor receptor domain II, IV, and kinase domain mutations in human solid tumors

Mutations that may predict response to adenosine 5-triphosphate (ATP)-mimetic epidermal growth factor receptor (EGFR) inhibitors occur in the EGFR kinase domain in lung adenocarcinomas and bronchioloalveolar carcinomas (BACs). Data on the frequency of EGFR mutations are sparse in other human tumors. Apart from the deletion mutant EGFRvIII, little is known about the frequency of mutations that encode for the EGFR extracellular domains II and IV that participate in receptor dimerization and formation of the tethered (autoinhibited) receptor conformation. We investigated 566 human neoplasms consisting of various histological types for mutations in exons 6, 7 (encode domain II), 14, 15 (domain IV), 18, 19, and 21 (the kinase domain) using denaturing high-performance liquid chromatography (DHPLC). Approximately 4,500 EGFR exons were screened for the presence of a mutation, and samples with an abnormal finding in DHPLC were sequenced. Only one mutation was found in the extracellular domain IV (glioblastoma), and none in domain II. Eight (11%) out of the 40 lung adenocarcinomas, or 33 BACs, investigated had exon 19 or 21 mutation in the kinase domain, but no mutations were found in other tumor types. Most of the lung cancers with mutated EGFR had three to six copies of the mutated gene in fluorescence in situ hybridization. We conclude that mutations of the EGFR kinase domain and the cysteine-rich extracellular domains are infrequent in most types of human cancer apart from lung adenocarcinoma. Mutated EGFR is usually not amplified in lung cancer.     

β连环素和表皮生长因子受体在非小细胞肺癌中表达的临床研究

目的:探讨β连环素和表皮生长因子受体在非小细胞肺癌中的表达及其临床意义。方法:采用免疫组化法回顾性研究了58例非小细胞肺癌标本β-catenin和EGFR的表达,并分析其表达与病理类型、分化程度和淋巴结转移的关系。结果:58例肺癌标本中β-catenin强阳性表达23例（36.66％）;EGFR强阳性表达27例（46.55％）,弱阳性表达19例（32.76％）;β-catenin和EGFR的表达与病理类型均无关;β-catenin的表达与分化程度有关;β-catenin和EGFR的表达均与有无淋巴结转移密切相关;β-catenin与EGFR的表达呈负相关关系（r=-0.3317,P=0.0110）。结论:β-catenin与EGFR的表达与非小细胞肺癌的生长分化、淋巴转移等恶性行为密切相关,EGFR的高表达可能与β-catenin表达水平降低有关。