Novel EGFR mutation-specific antibodies for lung adenocarcinoma: Highly specific but not sensitive detection of an E746_A750 deletion in exon 19 and an L858R mutation in exon 21 by immunohistochemistry

Objectives

Activating mutations in the epidermal growth factor receptor (EGFR) kinase domain are correlated with dramatic clinical responses in non-small cell lung cancer patients treated with EGFR-tyrosine kinase inhibitors (TKIs). The two most common EGFR mutations, representing 85–90% of EGFR mutations, are the E746_A750 deletion in exon 19 and the L858R point mutation in exon 21. We conducted this study to evaluate the suitability of mutation-specific antibodies that can detect E746_A750 deletion and L858R mutant EGFR proteins by immunohistochemistry (IHC).

Materials and methods

In a cohort of consecutive patients with surgically resected lung adenocarcinomas (n = 240), mutant EGFR protein expression was assessed by IHC using specific antibodies (clone SP111 and SP125) to the 2 major forms of EGFR mutations. Immunoreactivity was scored as 0–3, and the results were compared with the EGFR-mutational status.

Results

With a cutoff value of IHC 2+ for SP 111 (anti-EGFR E746_A750 del antibody) and SP 125 (anti-EGFR L858R antibody), both antibodies showed high specificity (99.0% and 89.7%, respectively) and sensitivity (70.6% and 80.4%, respectively). While cases with IHC scores of 3 using these 2 antibodies positively correlated with the EGFR-mutational status, cases with IHC scores lower than 3+ showed variable results regarding EGFR-mutational status.

Conclusion

Although each antibody showed relatively high specificity, some EGFR-mutant cases were not detected by the mutation-specific antibodies. Various forms of exon 19 deletions, except E746_A750, were rarely detected by the mutant-specific antibody. Therefore, IHC-negative cases require further molecular analysis to confirm the presence of EGFR mutations.     

Identification of non-small-cell lung cancer with activating EGFR mutations in malignant effusion and cerebrospinal fluid: rapid and sensitive detection of exon 19 deletion E746-A750 and exon 21 L858R mutation by immunocytochemistry

Background

Recently, we have reported that EGFR mutation-specific antibodies performed well in immunohistochemical analysis, with good sensitivity. We investigated whether this method could detect non-small-cell lung cancer (NSCLC) carrying EGFR mutations in malignant effusions and cerebrospinal fluid (CSF), comparable to the peptide nucleic acid–locked nucleic acid (PNA–LNA) PCR clamp assay. Furthermore, we compared activating EGFR mutations between primary and recurrent NSCLC.

Patients and methods

Twenty-four patients with NSCLC effusions and CSF were examined by immunocytochemistry using antibodies specific for the E746-A750 deletion mutation in exon 19 and the L858R point mutation in exon 21. The PNA–LNA PCR clamp assay was used to detect the E746-A750 deletion at exon 19, L858R mutation at exon 21, and T790M mutation at exon 20.

Results

We were able to identify EGFR mutations in NSCLC effusion and CSF with a sensitivity of 100% (5/5) using the anti-delE746-A750 antibody and 100% (8/8) using the anti-L858R antibody. Furthermore, in samples without these EGFR mutations, immunocytochemistry with the two specific antibodies identified 91% (10/11) as negative for both the deletion and the point mutations in EGFR. Activating EGFR mutations decreased in recurrent NSCLC compared with primary NSCLC, and the T790M mutation was detected in recurrent NSCLC of patients receiving gefitinib treatment.

Conclusions

Identification of EGFR mutations is important for patients with primary and recurrent NSCLC. Rapid and sensitive immunocytochemistry using mutation-specific antibodies to detect EGFR mutations will be useful for diagnosing responsiveness to EGFR-targeted drugs.     

Detection of drug-sensitizing EGFR exon 19 deletion mutations in salivary gland carcinoma

Activating mutations within the epidermal growth factor receptor (EGFR) identify lung adenocarcinoma patients with improved clinical responses to tyrosine kinase inhibitors gefitinib and erlotinib. By screening salivary gland carcinoma, two drug-sensitizing EGFR exon 19 delE746-A750 mutations were identified in an adenocystic and in a mucoepidermoid carcinoma of the parotid gland.     

盐酸埃克替尼治疗EGFR突变晚期肺腺癌的预后因素分析

目的 探讨晚期肺腺癌表皮生长因子受体（EGFR）突变患者应用表皮生长因子受体酪氨酸激酶抑制剂（EGFR-TKI）盐酸埃克替尼片治疗与预后的关系。方法 入组河北省胸科医院基因检测提示EGFR19、21基因突变且接受盐酸埃克替尼片治疗的晚期肺腺癌患者,分析其临床特征、EGFR基因突变亚型及不同位点与预后的关系。结果 全组共纳入101例晚期肺腺癌患者,EGFR基因19外显子缺失突变（EGFR Del19）58例,21外显子点突变（EGFR L858R）43例。全组患者客观缓解率达63.4%,中位无疾病进展时间（mPFS）和中位生存时间（mOS）分别为13个月和27个月。EGFR Del19对比EGFRL858R及EGFR19突变746~750位点对比其他突变位点的患者mPFS和mOS均增高。多因素分析显示,转移部位数和有无胸膜转移为OS的独立影响因素（P=0.027, P=0.041）,转移部位数≤3和无胸膜转移组患者的mOS分别为29个月和27个月。结论 盐酸埃克替尼片治疗晚期肺腺癌患者EGFR不同突变亚型和位点总生存差异不显著,转移部位数≤3和无胸膜转移的患者总生存期更长。     

中国肺腺癌患者上皮生长因子受体基因突变的研究

目的:分析我国肺腺癌患者上皮生长因子受体(EGFR)基因突变的发生率和突变类型。方法:在上海、杭州和昆明等地收集61例肺腺癌及其正常肺组织,采用PCR扩增和基因测序方法对组织DNA中EGFR外显子19~21基因突变进行分析。结果:正常肺组织中EGFR基因均为野生型,肺腺癌组织中EGFR基因突变检测率为47.5%(29/61),其中外显子19和21突变分别占突变总数的55.2%(16/29)和44.8%(13/29),外显子20未检测到突变。外显子19突变发生在第746~752位密码子,均为碱基缺失突变,有6种不同类型。外显子21突变全部是第858位密码子碱基替换突变。EGFR基因突变与患者性别和年龄无显著相关性。但昆明和上海等地患者的基因突变存在明显差异。结论:EGFR基因突变是一种肿瘤特异性的体细胞遗传改变,突变发生率约占肺腺癌总数的一半,其中以外显子19和21突变为主。我国EGFR基因突变存在地域差异。     

176例非小细胞肺癌的EGFR基因突变分析

目的 分析非小细胞肺癌（NSCLC）中上皮生长因子受体（EGFR）基因突变的发生率和突变类型。方法 收集123例正常肺组织和176例肺癌组织,采用PCR扩增和基因测序方法,对组织DNA中EGFR外显子19～21基因突变进行分析。结果 正常肺组织中EGFR基因均为野生型,肺癌组织中EGFR基因突变检测率为32．4％（57／176例）,其中,外显子19和21突变分别占突变总数的64．9％（37／57例）和31．6％（18／57例）,外显子20突变少见,仅占3．5％（2／57例）。外显子19突变发生在第746～753位密码子,均为碱基缺失突变,有7种不同类型。外显子20突变发生在第789—793位密码子,为碱基替换突变。外显子21突变全部是第858位密码子碱基替换突变。EGFR基因突变多见于女性,肺腺癌和腺鳞癌。结论 EGFR基因突变是一种肿瘤特异性的体细胞遗传改变,突变发生率约占肺癌总数的1／3,其中以外显子19和21为主。女性、肺腺癌和腺鳞癌中突变多见。     

Low correspondence of EGFR mutations in tumor tissue and paired serum of non-small-cell lung cancer patients

Objective:Epidermal growth factor receptor (EGFR) mutations are strong determinants of tumor response to EGFR tyrosine kinase inhibitors in non-small-cell lung cancer (NSCLC) patients. The aim of this study was to evaluate the correspondence between EGFR mutations in non-small-cell lung cancer tissues and in circulating DNA.Methods:The research was conducted in 50 non-small-cell lung cancer patients who had undergone curative surgery, and in whom both serum and neoplastic tissues were available. Meanwhile sera of 33 cases of advanced NSCLC patients were also analyzed. DNA were extracted from each sample. Mutations of EGFR in exonl 8-21 were examined by PCR amplification method and direct sequencing. Results:EGFR mutations were detected in 15 (30%) of 50 neoplastic tissue samples, 6 cases were in-frame deletion del E746-A750 in exon19, 9 cases were substitution in exon 21 (all were L858R except one was L861Q), but no mutated DNA resulted in paired serum circulating DNA samples of 50 resectable patients. As the 33 advanced NSCLC patients, EGFR mutations were detected in only 2 serum circulating DNA samples, all were L858R mutation in exon 21. Conclusion:These data indicated that it was difficult to identify EGFR mutations in circulating DNA of NSCLC patients. The use of EGFR mutation in serum as a clinical method for decision making of TKI therapy is unsatisfactory.     

Impact of Exon 19 Deletion Subtypes in EGFR-Mutant Metastatic Non–Small-Cell Lung Cancer Treated With First-Line Tyrosine Kinase Inhibitors

BackgroundCommon epidermal growth factor receptor (EGFR) mutations in non–small-cell lung cancer (NSCLC) predict sensitivity to EGFR tyrosine kinase inhibitors (TKIs), with exon 19 deletions being associated with better outcome compared to L858R mutations. We aimed to investigate the impact of different exon 19 deletions on patient outcome in EGFR-mutant NSCLC treated with first-line TKIs.Patients and MethodsIn this retrospective analysis, 106 patients with metastatic NSCLC harboring EGFR exon 19 deletions and treated with first-line TKIs were included. The primary end point was overall survival (OS), the secondary end point progression-free survival (PFS). Analyses were performed by grouping exon 19 deletions according to 2 models: we compared different type of deletion (delE746_A750 vs. deletions other than delE746-A750, defined as “uncommon”) or different starting codon of deletion (E746 vs. L747).ResultsThe frequency of uncommon deletions of exon 19 was 36%. When delE746_A750 (n = 68) was compared to the other deletions in exon 19 (n = 38), no differences were found, either in terms of OS (P = .65) or PFS (P = .65). Similarly, no difference in OS (P = .74) or PFS (P = .99) emerged when comparing the E746 group (n = 81) to the L747 group (n = 25). On multivariate analysis including clinical characteristics and type of deletions (delE746_A750 vs. uncommon deletions or E746 vs. L747), only the presence of brain metastases at diagnosis or during TKI treatment was associated with shorter PFS but not with worse OS.ConclusionDifferent exon 19 deletions are equally sensitive to first-line EGFR-TKIs in EGFR-mutant NSCLC.     

EGFR exon 20 insertion mutation in Japanese lung cancer

Mutations of the epidermal growth factor receptor (EGFR) gene have been reported in non-small cell lung cancer (NSCLC), especially in female, never smoker patients with adenocarcinoma. Some common somatic mutations in EGFR, including deletion mutations in exon 19 and leucine to arginine substitution at amino acid position 858 (L858R) in exon 21, have been examined for their ability to predict sensitivity to gefitinib or erlotinib. On the other hand, previous report has shown that the insertion mutation at exon 20 is related to gefitinib resistance. We investigated the exon 20 EGFR mutation statuses in 322 surgically treated non-small cell lung cancer cases. Two hundred and five adenocarcinoma cases were included. The presence or absence of EGFR mutations of kinase domains was analyzed by direct sequences. EGFR insertion mutations at exon 20 were found from 7 of 322 (2.17%) lung cancer patients. We also detected the 18 deletion type mutations in exon 19, and 25 L858R type mutations in exon 21. There was a tendency towards higher exon 20 insertion ratio in never smoker (never smoker 4.4% versus smoker 1.3%, p=0.0996) and female (female 4.5% versus male 1.3%, p=0.0917). Two exon 20 insertion cases were treated with gefitinib and failed to response. EGFR insertion mutation in exon 20 could not be ignored from Japanese lung cancers.     

Somatic mutations of EGFR gene in squamous cell carcinoma of the head and neck.

PURPOSE: Recently, the kinase domain mutations of epidermal growth factor receptor (EGFR) gene have been identified in non-small-cell lung cancer, and these mutations have been related to the clinical response to the tyrosine kinase inhibitor gefitinib. Gefitinib treatment has also shown clinical benefits in squamous cell carcinoma of the head and neck (SCCHN). The aim of this study was to explore the possibility that SCCHN harbored the EGFR mutations. EXPERIMENTAL DESIGN: In this study, we analyzed EGFR gene in 41 SCCHN for the detection of the somatic mutations by PCR-single-strand conformational polymorphism analysis. RESULTS: Overall, we detected three EGFR mutations (7.3%), and all of the mutations were the same in-frame deletion mutation in exon 19 (E746_A750del). CONCLUSION: These data indicated that in addition to non-small-cell lung cancer, SCCHN harbors the EGFR gene mutations, and suggested the rationale for the clinical applicability of gefinitib to SCCHN patients.     

晚期肺癌血清游离DNA中EGFR外显子19的基因突变研究

目的分析晚期肺癌的上皮生长因子受体(epidermal growth factor receptor,EGFR)外显子19基因突变的类型及发生率。方法从血清中提取游离DNA进行EGFR外显子19特异性PCR扩增和基因测序。结果24例肺部良性疾病血样中EGFR基因外显子19均为野生型;而130例肺癌血样中检出突变55例,EGFR外显子19基因突变的检出率为42.3%。外显子19基因突变均为第746~752位密码子的碱基缺失,共有7种突变类型。外显子19基因突变主要见于肺腺癌及小细胞肺癌,其检出率分别为58.9%和57.1%,突变与患者年龄及性别无明显相关性。在肺癌的不同组织类型中,外显子19的突变形式存在显著差异,肺腺癌的基因突变谱与肺鳞癌、腺鳞癌及小细胞肺癌明显不同。结论晚期肺癌病人的血清游离DNA中存在EGFR基因突变,这类突变可以通过适当的方法检测出来,这种血液检测方法在晚期肺癌的EGFR基因诊断及靶向治疗中具有广泛的应用价值。     

免疫组织化学法检测肺癌患者EGFR敏感突变的临床研究

目的 探讨免疫组织化学法（immunohistochemistry, IHC）检测EGFR突变的应用价值。方法 通过针对delE746-A750、L858R突变的特异性抗体检测肺癌患者EGFR突变状态,并且与DNA直接测序法进行对照。结果 136例标本中IHC评分0分的48例,其中DNA直接测序法检测突变的3例、评分1+的53例中突变的11例、2+的27例中突变的22例、 3+者中的8例均存在EGFR突变。以≤1+为阴性,≥2+为阳性,敏感度为71.43%,特异性为94.68%,阳性预测值（positive predictive value, PPV）为85.71%,阴性预测值（negative predictive value, NPV）为88.12%,κ值为0.683。结论 免疫组织化学检测EGFR突变应以评分≤1+为阴性,≥2+为阳性来评估EGFR突变状态。     

Detection of the EGFR mutation in exhaled breath condensate from a heavy smoker with squamous cell carcinoma of the lung

A 61-year-old male smoker (40 pack-years) presented with right chest pain. Computed tomography of the chest revealed a cavitary mass in the right lower lobe. A transbronchial biopsy showed squamous cell carcinoma. We examined epidermal growth factor receptor (EGFR) mutations in exhaled breath condensate (EBC). The DNA extracted from his EBC showed a deletion mutation in exon 19. Subsequently, the del E746-A750 mutation in exon 19 in a transbronchial tissue specimen was confirmed. Although he underwent whole-brain irradiation against multiple brain metastases, he had paralysis of the left side of the body and his performance status was 3. The patient was treated with gefitinib. He had marked tumor regression and no symptoms. Although only a small percentage of heavy smokers with squamous cell carcinoma harbor EGFR mutations, they probably benefit from EGFR-tyrosine kinase inhibitors. EGFR mutation status in the patients having such clinical features might be examined.     

Mutations of the epidermal growth factor receptor gene in lung cancer: biological and clinical implications

Recently it has been reported that mutations in the tyrosine kinase domain of the epidermal growth factor receptor(EGFR) gene occur in a subset of patients with lung cancer showing a dramatic response to EGFR tyrosine kinase inhibitors. To gain further insights in the role of EGFR in lung carcinogenesis, we sequenced exons 18-21 of the tyrosine kinase domain using total RNA extracted from unselected 277 patients with lung cancer who underwent surgical resection and correlated the results with clinical and pathologic features. EGFR mutations were present in 111 patients (40%). Fifty-two were in-frame deletions around codons 746-750 in exon 19, 54 were point mutations including 49 at codon 858 in exon 21 and 4 at codon 719 in exon 18, and 5 were duplications/insertions mainly in exon 20. They were significantly more frequent in female (P < 0.001), adenocarcinomas (P = 0.0013), and in never-smokers (P < 0.001). Multivariate analysis suggested EGFR mutations were independently associated with adenocarcinoma histology (P = 0.0012) and smoking status (P < 0.001), but not with female gender (P = 0.9917). In adenocarcinomas, EGFR mutations were more frequent in well to moderately differentiated tumors (P < 0.001) but were independent of patient age, disease stages, or patient survival. KRAS and TP53 mutations were present in 13 and 41%, respectively. EGFR mutations never occurred in tumors with KRAS mutations, whereas EGFR mutations were independent of TP53 mutations. EGFR mutations define a distinct subset of pulmonary adenocarcinoma without KRAS mutations, which is not caused by tobacco carcinogens.     

变性高效液相色谱技术检测非小细胞肺癌患者表皮生长因子受体基因突变的研究

 目的　探讨采用变性高效液相色谱（DHPLC）技术检测表皮生长因子受体（EGFR）基因突变的优势。方法　应用DHPLC技术检测49例非小细胞肺癌（NSCLC）患者EGFR基因第19与21外显子突变情况,并应用DNA直接测序法验证DHPLC检测基因突变的准确性。结果　49例NSCLC患者中,应用DHPLC检测出13例EGFR基因突变;其中第19外显子缺失突变10例（76.92 %）;第21外显子替代突变3例（23.08 %）。DNA直接测序法突变检测结果与DHPLC一致,DHPLC检测EGFR基因突变灵敏度为100 %。结论　DHPLC技术可以快速、准确、大规模筛选EGFR基因突变。     

Epidermal growth factor receptor gene mutations in papillary thyroid carcinoma

Recent studies have indicated that somatic mutations in the epidermal growth factor receptor (EGFR) gene have been identified in a subset of patients with nonsmall‐cell lung cancer (NSCLC) and are associated with sensitivity to the EGFR‐tyrosine‐kinase inhibitors. These mutations have been reported to be almost exclusively found in a pulmonary adenocarcinoma subgroup of NSCLC, with a low frequency in other solid tumors. We describe a patient with advanced‐stage papillary thyroid carcinoma (PTC) whose disease had been diagnosed as pulmonary adenocarcinoma at first, and who had a marked response to the EGFR‐tyrosine‐kinase inhibitor, gefitinib. An in‐frame deletion in exon 19 that eliminated 4 amino acids at positions 746 through 750, which is one of the common drug‐sensitive mutations in pulmonary adenocarcinoma, and a serine‐to‐proline substitution at codon 752, were found in a tumor specimen of the patient. We subsequently searched for mutations in the EGFR tyrosine kinase domain in primary tumors from 23 patients with PTC, and drug‐sensitive mutations commonly observed in pulmonary adenocarcinoma were found in 7 of these patients. Our observation of a high frequency of the EGFR‐activating mutations in PTC suggests that the EGFR mutation may be an important event in the development of PTC. EGFR gene amplification, also considered to be a predictor of response to EGFR‐tyrosine‐kinase inhibitors, was evaluated by fluorescence in situ hybridization (FISH); however, only 1 FISH‐positive tumor was detected. Our data suggest that EGFR‐tyrosine‐kinase inhibitors may deserve consideration in the treatment of a subset of patients with PTC, just as with pulmonary adenocarcinoma. © 2008 Wiley‐Liss, Inc.     

LncRNA expression profiles of EGFR exon 19 deletions in lung adenocarcinoma ascertained by using microarray analysis

Studies showed that long chain non-coding RNAs (lncRNAs) involved in the development and progression of lung cancer. However, the mechanisms of EGFR exon 19 deletion in lung adenocarcinoma were unclear. Lung adenocarcinoma was divided into EGFR exon 19 deletion group and EGFR wild-type group. We studied the differential expression profiles of lncRNAs in EGFR exon 19 deletion in lung adenocarcinoma by high-throughput microarray. Using abundant and varied probes, we were able to assess 30,586 lncRNAs and 26,109 mRNAs in our microarray. Compared with the wild-type EGFR, we found that 1,533 lncRNAs and 1,406 mRNAs were differentially expressed (≥twofold change) in EGFR exon 19 deletion in lung adenocarcinoma, indicating that many lncRNAs were significantly upregulated or downregulated in EGFR exon 19 deletion in lung adenocarcinoma. The 10 lncRNAs were aberrantly expressed in EGFR exon 19 deletion in lung adenocarcinoma compared with wild-type EGFR group validated by real-time RT-PCR. Among these, RP11-325I22.2 and LOC440905 were the most aberrantly expressed in 20 cases of EGFR exon 19 deletion in lung adenocarcinoma samples by real-time RT-PCR. Our study showed lncRNAs expression pattern in EGFR exon 19 deletion in lung adenocarcinoma by microarray. RP11-325I22.2 and LOC440905 might play an important role in the mechanism of EGFR exon 19 deletion in lung adenocarcinoma. The study may provide a new mechanism of EGFR exon 19 deletion in lung adenocarcinoma.     

DNA直接测序技术检测EGFR基因突变指导厄洛替尼一线治疗晚期非小细胞肺癌的临床观察

目的：通过对晚期非小细胞肺癌（non-small cell lung cancer,NSCLC）患者表皮生长因子受体（epi-dermal growth factor receptor,EGFR）基因突变的检测,探讨厄洛替尼（Erlotinib）一线治疗晚期NSCLC的疗效与安全性。方法：从110例NSCLC患者的肿瘤组织提取DNA,用DNA直接测序技术检测EGFR基因19、21外显子突变情况,31例EGFR基因突变患者中,30例患者口服厄洛替尼150mg/d,持续至疾病进展或发生不能耐受的药物不良反应,评价客观有效率（RR）,疾病控制率（DCR）,总生存（OS）,无疾病进展时间（PFS）,一年生存率和药物不良反应。结果：110例NSCLC组织中EGFR基因突变31（28%）例,其中19外显子缺失18（58%）例,21外显子点突变13（42%）例。EGFR基因突变率女性40%、肺腺癌33%、不吸烟者46%,高于男性、非腺癌、吸烟的病人。30例口服厄洛替尼患者,完全缓解（CR）3例,部分缓解（PR）21例,疾病稳定（SD）5例和疾病进展（PD）1例,客观有效率为80%,疾病控制率为97%,截止随访结束,仍有20例患者生存,故中位总生存未获得结果,无疾病进展时间为11.4个月,1年生存率为78%,厄洛替尼治疗晚期NSCLC最常见的不良反应是腹泻和皮疹,多为I-II级。结论：DNA直接测序检测晚期NSCLC患者EGFR基因突变具有高度敏感性,以EGFR基因突变结果为依据,一线应用厄洛替尼治疗晚期NSCLC患者,疗效明显,耐受性好,是治疗晚期NSCLC的最佳选择之一。     

Erlotinib response of EGFR-mutant gefitinib-resistant non-small-cell lung cancer

PURPOSE: Failure to gefitinib is generally believed to be associated with cross-resistance to other epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKI). Here we report a case whose active EGFR-mutant NSCLC responded to erlotinib treatment. PATIENT AND METHODS: Lung specimen was obtained during diagnostic procedures from a 41-year-old Taiwanese male smoker with adenocarcinoma. He received cisplatin-based chemotherapy following craniotomy to remove his brain metastasis. Tumor progressed in both lung and left adrenal gland. He underwent second-line docetaxel chemotherapy. Tumor progressed again 7 months later. He was subsequently treated with gefitinib 250mg QD. Complete regression of the lung tumor and partial response of the left adrenal gland mass was achieved. Nine months later, the left lower lobe lung tumor and left adrenal gland tumor progressed. A lung biopsy from the left lower lobe disclosed an adenocarcinoma which harbored an in-frame deletion in exon 19 (heterozygous delE746-A750) of EGFR without a second mutation such as T790M in exon 20. Subsequent erlotinib 150mg QD was administered. He experienced grade 1 skin rash, diarrhea and paronychia following erlotinib. RESULTS: This patient achieved a partial response to erlotinib treatment. He remained on erlotinib for a total of 18 months until the left adrenal gland tumor progressed. CONCLUSIONS: This case demonstrated that NSCLC bearing in-frame deletion in exon 19 of EGFR may respond to erlotinib treatment following gefitinib failure.     

Mutations within the tyrosine kinase domain of EGFR gene specifically occur in lung adenocarcinoma patients with a low exposure of tobacco smoking

Somatically acquired mutations in the epidermal growth factor receptor (EGFR) gene in lung cancer are associated with significant clinical responses to gefitinib, a tyrosine kinase inhibitor that targets EGFR. We screened the EGFR in 469 resected tumours of patients with lung cancer, which included 322 adenocarcinomas, 102 squamous cell carcinomas, 27 large cell carcinomas, 13 small cell carcinomas, and five other cell types. PCR with a specific condition was performed to identify any deletion in exon 19, while mutant-allele-specific amplification was performed to identify a mutation in codon 858 of exon 21. EGFR mutations were found in 136 cases (42.2%) with adenocarcinoma, in one case with large cell carcinoma, and in one case with pleomorphic carcinoma. An in-frame deletion in exon 19 was found in 62 cases while an L858R mutation was found in 77 cases. In the 322 cases with adenocarcinoma, these mutations were more frequently found in women than in men (P=0.0004), in well differentiated tumours than in poorly differentiated tumours (P=0.0014), and in patients who were never smokers than in patients who were current/former smokers (P<0.0001). The mutation was more frequently observed in patients who smoked 相似文献