Relationship between epidermal growth factor receptor gene mutation and copy number in Chinese patients with non-small cell lung cancer

Epidermal growth factor receptor(EGFR) gene mutation and copy number are useful predictive markers that guide the selection of non-small cell lung cancer(NSCLC) patients for EGFR-targeting therapy.This study aimed to investigate the correlation between EGFR gene mutation and copy number and clinicopathologic characteristics of Chinese patients with NSCLC.NSCLC specimens collected from 205 patients between November 2009 and January 2011 were selected to detect EGFR gene mutations with real-time polymerase chain reaction(RT-PCR) and to detect EGFR gene copy number with fluorescence in situ hybridization(FISH).EGFR mutations primarily occurred in females,non-smokers,and patients with adenocarinomas(all P < 0.001).Tissues from 128(62%) patients were FISH-positive for EGFR,including 37(18%) with gene amplification and 91(44%) with high polysomy.EGFR gene mutation was correlated with FISH-positive status(R = 0.340,P < 0.001).Multivariate analysis showed that not smoking(OR = 5.910,95% CI = 2.363-14.779,P < 0.001) and having adenocarcinoma(OR = 0.122,95% CI = 0.026-0.581,P = 0.008) were favorable factors for EGFR gene mutation.These results show a high frequency of EGFR FISH positivity in NSCLC tissues from Chinese patients and a significant relevance between EGFR gene mutations and FISH-positive status.Among the FISH-positive samples,EGFR gene mutation occurred more frequently in samples with gene amplification compared to those with high polysomy,suggesting that EGFR mutation and gene amplification should be used as clinical decision parameters to predict response to EGFR-targeting therapy.     

Combination of EGFR gene copy number and protein expression predicts outcome for advanced non-small-cell lung cancer patients treated with gefitinib.

BACKGROUND: Biological markers for optimal selection of patient to epidermal growth factor receptor (EGFR)-targeted therapies are not established in advanced non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: EGFR/HER2 gene copy number by FISH, EGFR protein and pAKT expression by immunohistochemistry (IHC) and EGFR and KRAS mutations were tested in 204 gefitinib-treated NSCLC patients. RESULTS: Increased EGFR and HER2 gene copy number (FISH+), EGFR protein overexpression (IHC+), EGFR mutations and pAKT overexpression were all associated with significantly higher response rates (33%, 29%, 22%, 39% and 20% respectively). EGFR FISH+ (32%) and IHC+ (61%) correlated with improved survival, while EGFR mutations (27%), KRAS mutations (26%) and pAKT expression (69%) did not. In multivariate survival analysis EGFR FISH and IHC were independent predictive markers. EGFR FISH+/IHC+ patients (23%) had a median survival of 21 months versus 6 months for double-negative patients (30%). CONCLUSION: Combination of EGFR FISH and IHC is effective predictor for benefit from gefitinib. Patients with double-negative results are unlikely to benefit in western NSCLC populations.     

非小细胞肺癌组织中表皮生长因子受体基因突变与拷贝数之间的相关性以及与患者临床病理特征之间的关系

目的 研究中国非小细胞肺癌(NSCLC)患者组织中表皮生长因子受体(EGFR)基因状态,分析EGFR基因突变与拷贝数之间的相关性以及与NSCLC患者临床病理特征之间的关系。方法 应用实时荧光定量PCR法检测118例NSCLC组织中EGFR基因的突变状态,同时采用荧光原位杂交(FISH)技术检测EGFR基因拷贝数。分析EGFR基因突变与拷贝数之间的相关性,探讨EGFR基因状态与NSCLC患者临床病理特征之间的关系。结果118例NSCLC组织中,EGFR基因的突变率为41.5％,其中腺癌为50.0％,鳞癌为5.0％。EGFR基因FISH阳性率为70.3％,其中29例为基因扩增,54例为高度多体性;腺癌FISH阳性率为78.1％,鳞癌为35.0％。EGFR基因突变与EGFR基因高拷贝数主要存在于腺癌、晚期、女性和不吸烟的患者,EGFR基因突变与EGFR基因拷贝数之间有显著的相关性。结论在中国NSCLC患者中,腺癌、晚期、女性、不吸烟的患者EGFR基因突变率和FISH阳性率较高,且二者具有显著的相关性;联合检测EGFR基因拷贝数和基因突变可能更有利于NSCLC靶向药物的筛选。     

Increased epidermal growth factor receptor (EGFR) gene copy number is strongly associated with EGFR mutations and adenocarcinoma in non-small cell lung cancers: a chromogenic in situ hybridization study of 182 patients

SUMMARY: To evaluate the association of epidermal growth factor receptor (EGFR) gene copy number with EGFR and k-ras mutation status and tyrosine kinase inhibitor (TKI) sensitivity in non-small cell lung cancer (NSCLC), EGFR gene copy number of 182 NSCLC tumor specimens were analyzed by chromogenic in situ hybridization (CISH). EGFR and k-ras mutation analyses were also performed for, respectively, 176 and 157 of the 182 patients. Additionally, 36 patients in this study had received TKI monotherapy. The tumor was considered to be CISH positive if the gene copy number was >or=5 signals per nucleus in >or=40% of tumor cells. CISH-positive tumors were strongly associated with adenocarcinoma (56.8%) compared with squamous cell carcinoma (15.9%) (p<0.0001). The CISH-positive tumors were also strongly associated with EGFR mutations (78%) compared with wild type (20.2%) (p<0.0001). Only six tumors had k-ras mutations. None had EGFR mutation and only one was CISH positive. In the patients treated with TKI, EGFR mutation was strongly associated with TKI responsiveness (22/25 responders) (p<0.0001), but the CISH-positive tumors were only marginally significant (18/25 responders) (p=0.0665). Patients with EGFR mutations or CISH-positive tumors were all associated with longer median survival, although not statistically significant. Our results suggest Increased EGFR copy number was highly correlated with EGFR mutation in adenocarcinoma. Although it is less correlated with TKI responsiveness when compared with EGFR mutations, it still could be a good alternative molecular predictive marker for TKI responsiveness, since CISH can be done on paraffin section and is much quicker than DNA sequencing.     

Clinicopathologic features and prognostic implications of epidermal growth factor receptor (EGFR) gene copy number and protein expression in non-small cell lung cancer

Increased epidermal growth factor receptor (EGFR) gene copy numbers and mutations predict sensitivity to EGFR tyrosine kinase inhibitor in non-small cell lung cancer (NSCLC). However, the clinicopathologic features of EGFR gene copy status in NSCLC remain unclear. We retrospectively analyzed 262 cases of NSCLC, including 135 squamous cell carcinomas (SCC) and 112 adenocarcinomas (ADC), for which paraffin blocks of the resected primary lung mass were available. None had received EGFR-targeted therapy. EGFR gene copy number was evaluated using fluorescence in situ hybridization (FISH), and EGFR expression was determined immunohistochemically using a tissue microarray. A high EGFR gene copy (EGFR FISH-positive) was found in 30.2% of the cases (amplification in 11.1% and high polysomy in 19.1%). There was no significant difference in EGFR FISH status with respect to SCC and ADC histology. The EGFR FISH-positive rate was higher in non-smokers than in smokers in the multivariate analysis (p=0.012). EGFR expression was significantly associated with a high EGFR gene copy and SCC histology (p=0.000). In the univariate survival analysis, EGFR FISH-positivity predicted worse survival in SCC (p=0.059), especially stage I SCC (p=0.04). EGFR amplification was associated with a shorter survival in node-positive SCC (p=0.015). However, the EGFR gene copy number or protein expression had no influence on the prognosis of ADC. In conclusion, the EGFR FISH-positive rate in Korean patients with NSCLC was similar to rates in Western populations, unlike the higher frequencies of EGFR mutation in East Asians. A high EGFR gene copy number was significantly more common in non-smokers, as were EGFR mutations. A high EGFR gene copy number predicted worse survival in SCC; therefore, the prognostic implications of the EGFR gene and protein should be analyzed in the context of histology and staging in NSCLC.     

Digital PCR analysis of plasma cell-free DNA for non-invasive detection of drug resistance mechanisms in EGFR mutant NSCLC: Correlation with paired tumor samples

As the development of resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) has become an issue of concern, identification of the mechanisms responsible has become an urgent priority. However, for research purposes, it is not easy to obtain tumor samples from patients with EGFR mutation-positive non-small-cell lung cancer (NSCLC) that has relapsed after treatment with EGFR-TKIs. Here, using digital PCR assay as an alternative and noninvasive method, we examined plasma and tumor samples from patients with relapsed NSCLC to establish the inter-relationships existing among T790M mutation, activating EGFR mutations, HER2 amplification, and MET amplification. Paired samples of tumor and blood were obtained from a total of 18 patients with NSCLC after they had developed resistance to EGFR-TKI treatment, and the mechanisms of resistance were analyzed by digital PCR. Digital PCR analysis of T790M mutation in plasma had a sensitivity of 81.8% and specificity of 85.7%, the overall concordance between plasma and tissue samples being 83.3%. MET gene copy number gain in tumor DNA was observed by digital PCR in three patients, of whom one exhibited positivity for MET amplification by FISH, whereas no patient demonstrated MET and HER2 copy number gain in plasma DNA. Digital PCR analysis of plasma is feasible and accurate for detection of T790M mutation in NSCLC that becomes resistant to treatment with EGFR-TKIs.     

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 HER2 and EGFR gene status on gefitinib-treated patients with nonsmall-cell lung cancer

We previously examined the relationship between epidermal growth factor receptor (EGFR) status and clinical outcomes of nonsmall-cell lung cancer (NSCLC) patients treated with gefitinib. In our study, we additionally examined HER2 status and investigate the impact of genetic status as predictors in Japanese NSCLC patients treated with gefitinib. The HER2 copy number status was determined by fluorescence in situ hybridization assay and mutation of HER2 exon 20 was determined by direct sequencing in 74 patients to investigate the relationship between molecular statuses including HER2 and EGFR and the clinical outcomes of patients treated with gefitinib. The high HER2 copy number was identified in 32 (43.2%) of 74 NSCLC patients and no HER2 exon 20 mutations were found. The high HER2 copy number was significantly associated with the sensitivity to gefitinib (p = 0.0045) and a prolonged progression-free survival (PFS) (p = 0.0089) in a univariate analysis, but not in a multivariate analysis. Multivariate analyses exhibited that the drug-sensitive EGFR mutation was an independent predictive factor of a better sensitivity to gefitinib (OR = 41.9, p = 0.002), prolonged overall survival (HR = 0.32, p = 0.019) and PFS (HR = 0.31, p = 0.0045). The high EGFR copy number might have a weak association with better response and prognosis without statistical significance. In conclusion, the drug-sensitive EGFR mutation, rather than HER2 and EGFR copy numbers, is a determinant of favorable clinical outcomes in gefitinib-treated patients with NSCLC, although the high HER2 copy number, to some extent, may influence the gefitinib effect.     

EGFR protein overexpression and gene amplification in squamous cell carcinomas of the esophagus

Overexpression of epidermal growth factor receptor (EGFR) is observed in many cancers, sometimes accompanied by gene amplification. Recently, several clinical therapies targeting EGFR were developed, but the eligibility criteria for these therapies is not fully established. To develop such eligibility criteria for esophageal squamous cell carcinoma (ESCC), we sought to clarify: (i) the exact frequency of EGFR overexpression, (ii) the relationship between protein overexpression and gene amplification, (iii) the relationship between gene amplification and specific gene mutations and (iv) the correlation between the status of EGFR and clinical or pathological features. Immunohistochemistry revealed that EGFR protein is overexpressed in 53 (50%) of the 106 ESCC examined. Fluorescence in situ hybridization (FISH) indicated clear EGFR gene amplification in 15 of the 53 tumors, somewhat higher EGFR copy in 32 cases, and no increase in 6 cases. Gene amplification was significantly associated with high level overexpression. Direct sequencing of exons 19 and 21 of EGFR revealed no mutations in 15 tumors exhibiting gene amplification, and no mutations in 25 tumors not exhibiting gene amplification. Overexpression of EGFR was significantly correlated with depth of invasion of the tumor.In conclusion, anti-EGFR therapies may be appropriate for patients with ESCC. We assume that combined analyses by immunohistochemistry/FISH would clarify aberrations in protein and gene function, and could help to identify those patients who may benefit from anti-EGFR therapy.     

Direct serum and tissue assay for EGFR mutation in non-small cell lung cancer by high-resolution melting analysis

Biological therapy with epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) have noted promising outcomes for patients with non-small cell lung carcinoma (NSCLC), especially those with mutated EGFR. Tissue EGFR gene mutation testing can predict the benefit of taking a first-line EGFR-TKI, thus, allowing the physician to prescribe the most suitable therapy. Unfortunately, most lung cancer patients, especially NSCLC patients present with advanced disease that is surgically unresectable. The goal of this study was to develop high-resolution melting (HRM) assays to detect EGFR mutations in exons 18 to 21, compare their sensitivity and concordance to direct sequencing, and evaluate the feasibility and reliability of serum as a tissue alternate for routine EGFR mutation screening. EGFR mutations of 126 Formalin-Fixed Paraffin-Embedded (FFPE), 47 fresh frozen tissues and from 47 matched pre-operation serum specimens of NSCLC patients were screened by the HRM assays. EGFR mutations by HRM were confirmed through sequencing. We found 78 EGFR mutations in 70 FFPE tissues, 25 EGFR mutations in 24 fresh frozen tissues, with a mutation rate of 55.56% (70/126) and 51.06% (24/47), respectively. Most mutations were correctly identified by sequencing. EGFR mutations were detected in 22 serum samples from 24 tissue EGFR mutation-positive patients. The concordance rate between serum and tissue in EGFR mutation screening was 91.67%. We conclude that the HRM assay can provide convincing and valuable results both for serum and tissues samples, thus, it is suitable for routine serum EGFR mutation screening for NSCLC patients, especially those surgically unresectable.     

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。     

Assessment of EGFR and K-ras mutations in fixed and fresh specimens from transesophageal ultrasound-guided fine needle aspiration in non-small cell lung cancer patients

In non-small cell lung cancer (NSCLC) patients, somatic EGFR and K-ras mutations predict therapeutic effectiveness and resistance, respectively, to EGFR tyrosine kinase inhibitors (TKIs). Transesophageal ultrasound-guided fine needle aspiration (EUS-FNA) is a validated technique for diagnosis and staging of NSCLC. In the present study, we compared the feasibility and reliability of EGFR and K-ras gene mutation analysis in fixed and fresh mediastinal lymph nodes and extra-lymph nodal samples obtained by EUS-FNA in patients suspicious for NSCLC. Thirty-six patients were enrolled into the study. For each patient, DNA was extracted from both fresh samples and fixed cytological smears. Exons 18-21 of EGFR and exon 2 of K-ras were amplified by PCR and mutation status was determined by direct sequencing and pyrosequencing. All cases were eligible for analysis. NSCLC was diagnosed in 32 patients (25 adenocarcinomas and 7 squamous cell carcinomas) and 4 patients were free of malignancy. Of the 25 patients with adenocarcinoma, EGFR mutations were detected in 2 (8%) fresh tumor samples and in 3 (12%) fixed cytological smears. K-ras mutations were detected in 8 (32%) fresh samples, and in 9 (36%) fixed cytological smears. Fixed and stained cytological samples seem to be more reliable than fresh material for molecular analysis.     

EGFR FISH versus mutation: different tests, different end-points

Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) demonstrated to significantly improve survival of non-small cell lung cancer patients (NSCLC) previously exposed to chemotherapy. Although clinical features, particularly smoking history, help physicians for identifying the sensitive population, a proper patient selection should not preclude to drug target assessment. EGFR mutations or increased EGFR gene copy number assessed by fluorescence in situ hybridization (FISH) identify NSCLC with the highest chance to respond to the therapy. Although indirect comparisons suggest that mutation analysis is the best available technique for identification of responders, survival improvement is not confined to individuals with tumor shrinkage. For patients with metastatic NSCLC, where definitive cure in not achievable, response is probably not the best end-point, since survival improvement observed with TKI included also patients with stable or progressive disease. Data from large randomized studies indicated that FISH technology is probably the best method for patient selection when the main end-point is survival. FISH was the only EGFR test significantly associated with prolonged survival in large randomized trials with a control arm of placebo, the only studies able to discriminate between predictive and prognostic value of such biomarkers. Moreover, in absence of any convincing data on the prognostic role of EGFR FISH or EGFR mutations, results from large phase III trials suggest that patients with clinical or biological predictors for TKI sensitivity survive longer when exposed to standard chemotherapy, a relevant aspect that should be considered in designing clinical trials.     

KRAS mutation is an important predictor of resistance to therapy with epidermal growth factor receptor tyrosine kinase inhibitors in non-small-cell lung cancer.

PURPOSE: EGFR gene mutations and increased EGFR copy number have been associated with favorable response to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (EGFR-TKI) in patients with non-small-cell lung cancer (NSCLC). In contrast, KRAS mutation has been shown to predict poor response to such therapy. We tested the utility of combinations of these three markers in predicting response and survival in patients with NSCLC treated with EGFR-TKIs. EXPERIMENTAL DESIGN: Patients with advanced NSCLC treated with EGFR-TKI with available archival tissue specimens were included. EGFR and KRAS mutations were analyzed using PCR-based sequencing. EGFR copy number was analyzed using fluorescence in situ hybridization. RESULTS: The study included 73 patients, 59 of whom had all three potential markers successfully analyzed. EGFR mutation was detected in 7 of 71 patients (9.8%), increased EGFR copy number in 32 of 59 (54.2%), and KRAS mutation in 16 of 70 (22.8%). EGFR mutation (P<0.0001) but not increased EGFR copy number (P=0.48) correlated with favorable response. No survival benefit was detected in patients with either of these features. KRAS mutation correlated with progressive disease (P=0.04) and shorter median time to progression (P=0.0025) but not with survival. Patients with both EGFR mutation and increased EGFR copy number had a >99.7% chance of objective response, whereas patients with KRAS mutation with or without increased EGFR copy number had a >96.5% chance of disease progression. CONCLUSION: KRAS mutation should be included as indicator of resistance in the panel of markers used to predict response to EGFR-TKIs in NSCLC.     

Prospective study of the accuracy of EGFR mutational analysis by high-resolution melting analysis in small samples obtained from patients with non-small cell lung cancer

PURPOSE: Epidermal growth factor receptor (EGFR) mutations, especially in-frame deletions in exon 19 (DEL) and a point mutation in exon 21 (L858R), predict gefitinib sensitivity in patients with non-small cell lung cancer (NSCLC). In this study, we verified the accuracy of EGFR mutation analysis in small samples by high-resolution melting analysis (HRMA), which is a rapid method using PCR amplification with a dye to analyze the melting curves in NSCLC. EXPERIMENTAL DESIGN: We designed a prospective study to compare the sensitivity and specificity of HRMA and DNA sequencing with laser capture microdissection. Eligible patients with lung lesions were screened by bronchoscopy or percutaneous needle biopsy to histologically confirm the diagnosis, followed by surgical resection of the NSCLC. Small diagnostic specimens were analyzed for EGFR mutations by HRMA, and the surgically resected specimens were examined for mutations by HRMA and DNA sequencing. RESULTS: The analyses for EGFR mutations were conducted in 52 eligible cases of the 92 enrolled patients. EGFR mutations were detected in 18 (34.6%) patients. The results of HRMA from surgically resected specimens as well as DNA sequencing revealed 100% sensitivity and specificity. On the other hand, the sensitivity and specificity of HRMA from the small diagnostic specimens were 83.3% and 100%, respectively. CONCLUSIONS: In this study, we showed that HRMA is a highly accurate method for detecting DEL and L858R mutations in patients with NSCLC, although it is necessary to consider the identification of patients with a false-negative result when the analysis is conducted using small samples.     

Analysis of EGFR Mutation Status in Algerian Patients with Non-Small Cell Lung Cancer

Background and objective: Epidermal growth factor receptor (EGFR) mutation status is used as a predictive biomarker for the tyrosine kinase inhibitors therapy in non-small cell lung cancer (NSCLC). The incidence of EGFR mutations appears to vary according to ethnic and geographical backgrounds. This retrospective study aimed to investigate the EGFR mutation status in Algerian NSCLC patients and its association with clinicopathological features. Methods: We examined the presence of EGFR mutations (Exons 19-21) in 58 unselected  NSCLC samples using PCR followed by direct sequencing. Results: The present study included 53 (91.4%) men and 5 (8.6%) women, with a median age of 59 (ranging from 44 to 94 years old). EGFR mutations were detected in 23 patients, with an overall rate of 39.6%. There were 21 (91.3%) cases with the exon-21 L585R single mutation and two (8.7%) with dual mutations of exon-19 deletions and L585R. EGFR mutations were more frequently found in patients with confirmed adenocarcinoma (14/27, 51.8%) than in non-adenomatous NCSCL subtypes (3/14, 21.4%; p=0.03). Furthermore, early stages of the disease were significantly associated with a higher rate of EGFR mutations (14/27, 51.8%) compared with those at  advanced stage (5/21, 23.8%; p=0.02). There were no significant differences in EGFR mutation frequency by age, gender, or smoking status. Conclusion: We found that Algerian NSCLC patients exhibited a high rate of EGFR mutations, which was quite similar to that in Asians population rather than Caucasian patients. Thus, TKI-based treatments may be more beneficial for Algerian patients with NSCLC. Further studies using a large number of patients are required to confirm our preliminary findings.     

Response to treatment and survival of patients with non-small cell lung cancer undergoing somatic EGFR mutation testing

Somatic mutations in the epidermal growth factor receptor (EGFR) gene are associated with clinical response and prolonged survival in patients with non-small cell lung cancer (NSCLC) treated with EGFR tyrosine kinase inhibitors (TKIs). We began screening patients for somatic EGFR mutations by DNA sequencing as part of clinical care in 2004. We performed a retrospective cohort study of 278 patients with NSCLC referred for EGFR testing over a 10-month period. Tumor samples underwent direct DNA sequence analyses of EGFR exons 18 through 24. We determined the clinical characteristics and EGFR mutation status of the patients and analyzed their response to therapy and survival. EGFR somatic mutations were identified in 68 (24%) of patients. A minimal smoking history was the strongest clinical predictor of harboring a mutation. In multivariable analyses, each pack-year of smoking corresponded to a 5% decreased likelihood of having an EGFR mutation. Among 92 patients with unresectable disease undergoing subsequent systemic therapy, EGFR mutations were associated with an increased response rate to EGFR TKIs (p < .0001) but not chemotherapy. Overall survival was significantly prolonged in EGFR mutation-positive patients (p = .001), with a median survival of 3.1 years compared with 1.6 years in mutation-negative patients, after adjusting for age, gender, and stage at diagnosis. Integrating molecular profiling into clinical care is feasible in NSCLC patients and provides useful clinical information.     

Biomarkers for prediction of sensitivity to EGFR inhibitors in non-small cell lung cancer

PURPOSE OF REVIEW: Epidermal growth factor receptor (EGFR) Inhibitors have shown promising results in patients with advanced non-small cell lung cancers (NSCLC) who previously have failed on chemotherapy. Objective response is achieved in 10 to 28% of the patients, and about 30% will achieve stable disease. A major problem is how to select the patients, who will benefit from treatment, and who will not. RECENT FINDINGS: The predictive role of EGFR protein expression assessed by IHC is still debated. Specific EGFR gene mutations have been identified associated with response to gefitinib (Iressa(R)), but seem not to be associated with stable disease. No studies have yet demonstrated any association between EGFR gene mutations and survival. In this review we describe other marker studies, which are associated with sensitivity to EGFR inhibitors. Increased EGFR gene copy number based on FISH analysis is demonstrated to be a good predictive marker for response, stable disease, time to progression, and survival. SUMMARY: EGFR/FISH seems today to be the best predictive marker for clinical benefit from EGFR inhibitors in NSCLC. Prospective large scale clinical studies must identify the most optimal paradigm for selection of patients.     

Impact of epidermal growth factor receptor (EGFR) kinase mutations, EGFR gene amplifications, and KRAS mutations on survival of pancreatic adenocarcinoma

BACKGROUND: Erlotinib, in combination with gemcitabine, has shown clinical benefits in pancreatic adenocarcinoma patients. The presence of EGFR mutations and increased EGFR copy numbers in pancreatic adenocarcinoma was explored. METHODS: Sixty-six pancreatic cancer patients were included in the analysis. The EGFR mutation was analyzed by DNA sequencing of exons 18-21 in the tyrosine kinase domain. KRAS mutation was analyzed by sequencing codons 12, 13, and 61. Quantitative real-time polymerase chain reaction was performed to analyze the copy number of EGFR. RESULTS: In the current study the EGFR mutation was harbored in only 1 (1.5%) of the 66 inoperable or metastatic pancreatic adenocarcinoma patients. Amino acid substitution was detected in exon 20 of the EGFR gene. Increased EGFR copy numbers (> or =3.0 per cell) were detected in 26 (41%) patients. There was only 1 patient, who had a highly increased EGFR copy number (> or =6.0 per cell), who died, 2.1 months from the date of diagnosis. The EGFR amplification did not significantly influence survival in pancreatic adenocarcinoma patients (P = .935). Thirty-two (49%) of the 65 pancreatic adenocarcinomas examined harbored a point mutation in codons 12 (n = 31) and 61 (n = 1) of the KRAS gene. The presence of a point mutation in codon 12 adversely influenced survival of pancreatic cancer patients (P = .030). CONCLUSIONS: The incidence of somatic mutations in the tyrosine kinase domains of EGFR was very low and the increased gene copy number of EGFR did not significantly influence survival.     

Comprehensive Analysis of EGFR-Mutant Abundance and Its Effect on Efficacy of EGFR TKIs in Advanced NSCLC with EGFR Mutations

IntroductionA qualitative detection method for EGFR mutations is not sufficient to guide precise targeted therapy in clinical practice. The aim of this study was to explore the relationship between the abundance of EGFR mutations and efficacy of EGFR tyrosine kinase inhibitors (TKIs).MethodsWe used the amplification refractory mutation system (ARMS) method optimized with competitive blockers and specific mutation quantitation (ARMS+) to quantitatively evaluate the abundance of EGFR mutations in 201 patients with advanced NSCLC. A cutoff value of the abundance of EGFR mutations was determined by receiver operating characteristic analysis in a training group and validated in a validation group.ResultsThe abundance of EGFR activating mutation by ARMS+ was significantly associated with objective response to EGFR TKIs. The abundance of 19DEL was significantly higher than that of L858R, with cutoff values for 19DEL and L858R of 4.9% and 9.5%, respectively. The median progression-free survival in the high group was significantly longer than that in the low group (19DEL, 15.0 versus 2.0 months [p < 0.001] and L858R, 12.3 versus 2.0 months [p < 0.001]) in the training set. Similar results were also observed in the validation set. Nine of 13 patients harboring T790M mutation achieved a partial response to EGFR TKIs. Most (seven of nine) were identified to have a low abundance of T790M mutation. The abundance of EGFR mutations appeared to be more significantly associated with the copy number of EGFR mutations from circulating tumor DNA in 19DEL group.ConclusionThe abundance of EGFR activating mutation by ARMS+ was significantly associated with objective response to EGFR TKIs. The abundance of EGFR^T790M mutation may have an adverse impact on progression-free survival rather than on objective response rate in patients with advanced EGFR-mutant NSCLC treated with EGFR TKIs.