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Lung Cancer

Good Response to Gefitinib in Lung Adenocarcinoma of Complex Epidermal Growth Factor Receptor (EGFR) Mutations with the Classical Mutation Pattern

^aDepartment of Internal Medicine, ^bDepartment of Pathology, and ^cDepartment of Oncology, National Taiwan University Hospital, Taipei, Taiwan; ^dDepartment of Molecular Biotechnology, Da-Yeh University, Chang-Hua, Taiwan

Key Words. EGFR mutation • Gefitinib • Lung cancer • EGFR TKI • Complex mutation pattern

Correspondence: Jin-Yuan Shih, M.D. Ph.D., Department of Internal Medicine, National Taiwan University Hospital, No. 7, Chung-Shan South Road, Taipei 100, Taiwan. Telephone: 886-2-23562905; Fax: 886-2-23582867; e-mail: jyshih{at}ntu.edu.tw

Received April 14, 2008; accepted for publication November 10, 2008; first published online in THE ONCOLOGIST Express on December 5, 2008.

Disclosure: Employment/leadership position: None; Intellectual property rights/inventor/patent holder: None; Consultant/advisory role: Chih-Hsin Yang, AstraZeneca; Honoraria: None; Research funding/contracted research: None; Ownership interest: None; Expert testimony: None; Other: None.

	ABSTRACT

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Background. Epidermal growth factor receptor (EGFR) mutations are usually detected in lung adenocarcinoma and are associated with a response to EGFR tyrosine kinase inhibitors (TKIs). However, not all EGFR mutations have similarly high clinical response rates. This study aimed to investigate the clinical characteristics and response to gefitinib in lung adenocarcinoma patients with complex EGFR mutations.

Materials and Methods. Three hundred thirty-nine specimens of lung adenocarcinoma from patients treated with gefitinib were collected for EGFR sequencing. Nineteen patients with complex EGFR mutations were enrolled for the study after excluding three patients with the EGFR T790M mutation, which confers resistance to gefitinib.

Results. Among the 19 patients, 12 had complex mutations with the classical mutation pattern (L858R or deletion in exon 19). When compared with those without the classical mutation pattern, patients with this mutation pattern had a higher response rate (83% versus 29%), longer progression-free survival duration (median, 12.7 months versus 4.9 months), and longer overall survival time (median, 24.7 months versus 12.3 months) after gefitinib treatment.

Comparing patients harboring complex EGFR mutations with a classical mutation pattern with those harboring single classical mutations, there were no statistical differences in the response rate (83% versus 73%), progression-free survival time (median, 12.7 months versus 8.1 months,) or overall survival time (median, 24.7 months versus 16.4 months).

Conclusion. Patients with complex EGFR mutations with the classical mutation pattern had the same response rate, progression-free survival duration, and overall survival time as those with single classical mutations. EGFR TKIs may be the choice of treatment for this type of lung adenocarcinoma.

	INTRODUCTION

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Epidermal growth factor receptor (EGFR) is a member of the ErbB receptor family and is a transmembrane glycoprotein encoded by a gene located in the short arm of chromosome 7 [1]. Activation of EGFR controls cell proliferation, antiapoptosis, angiogenesis, differentiation, and invasion [2], which are regulated via the phosphorylation of several tyrosine kinase residues after ligands bind to the extracellular domain of EGFR. The expression of EGFR is correlated with poor prognosis and is seen in 50% of non-small cell lung cancer (NSCLC) cases on immunohistochemistry [3].

The EGFR tyrosine kinase inhibitors (TKIs) gefitinib (Iressa®; AstraZeneca, Wilmington, DE) and erlotinib (Tarceva®; Genentech, South San Francisco, CA) are used to treat NSCLC. A higher response to EGFR TKIs is noted in specific subgroups that include females, never smokers, patients with adenocarcinoma histology, and East Asians [4, 5]. Higher EGFR mutation rates are also noted in these subgroups [6] and are also related to a better response to EGFR TKIs and longer survival [7–9]. The in-frame deletion in exon 19 (del-19) accounts for 45% of mutations, while the point mutation L858R in exon 21 accounts for around 40%–45% of EGFR mutations in lung cancer [3, 7, 8, 10–13].

Patients with both the del-19 and the L858R mutations have good responses to EGFR TKIs and these are termed "classical mutations" [11]. Patients with these mutations exhibit objective response rates in the range of 75%–95% [7–9, 14–16]. In addition to the classical mutations, other EGFR mutations in exons 18–21 have also been reported, although quite rarely. Patients with these nonclassical mutations have variable responses to EGFR TKIs [12, 17, 18].

Most studies on the relationship between EGFR mutations and response to EGFR TKIs show a single site mutation. However, two or more concomitant sites of EGFR mutations have also been detected despite the low patient number. Chen et al. [19] showed that the frequency of double EGFR mutations is around 6% in all EGFR mutations of lung cancer by an analysis of the literature. Concomitant EGFR mutations have been termed "complex mutations" [20]. A second mutation may substantially alter the biological properties of the mutant EGFR and sensitivity to TKIs [21]. For example, T790M is a noteworthy acquired EGFR mutation after EGFR TKI treatment in patients with L858R or del-19, which confers resistance to EGFR TKI treatment [22, 23].

Although most studies have shown that patients with EGFR mutations have a good response to gefitinib, it remains uncertain whether patients with complex EGFR mutations have a similarly good response. This study investigated the clinical characteristics and response to gefitinib of patients with lung adenocarcinoma and complex EGFR mutations. Because T790M is a well-known gefitinib resistance mutation, we excluded those patients with T790M from this analysis. A literature review of all published reports on complex EGFR mutations and EGFR TKI responsiveness is also provided.

	MATERIALS AND METHODS

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Patients and Tissue Procurement
The study group included lung adenocarcinoma patients diagnosed at the National Taiwan University Hospital between June 2004 and July 2007. Tumor specimens obtained by either surgical or needle biopsy/aspiration procedures, including primary lung tumors, malignant effusion cell blocks, and other distant metastases, were sequenced for mutational analysis. Written informed consent for use of the tissue in a molecular analysis was acquired from the patients at the procurement of the tumor specimens. This study was approved by the institutional review board of the National Taiwan University Hospital.

Lung cancer histology was defined according to the World Health Organization pathology classification [24]. A complete lung cancer staging workup was performed as routine practice, which included bronchoscopy, computed tomography (CT) of the head, chest, and abdomen, and whole-body bone scintigraphy. The date of diagnosis, all chemotherapy received, and responsiveness to the chemotherapy were recorded.

All patients with stage IIIb or IV NSCLC who received gefitinib were identified from the records of the Department of Pharmacy in the hospital. Their clinical data, including demographic information, cancer cell type, smoking status, and imaging studies, were collected. Patients who had smoked <100 cigarettes in their lifetime were categorized as nonsmokers. Those who had smoked within 1 year of the diagnosis were categorized as current smokers. The rest were categorized as former smokers.

Response Evaluation of Lung Adenocarcinoma Patients
Gefitinib was taken orally at a dose of 250 mg daily. No concurrent chemotherapy or radiotherapy for the lung tumors was given during gefitinib therapy. Chest radiography every 2–4 weeks and a chest CT scan (including the liver and adrenal glands) every 2–3 months were performed as routine clinical practice, and as needed to confirm response and disease progression.

The unidimensional method was used according to the Response Evaluation Criteria in Solid Tumors (RECIST) guidelines for measuring solid tumors [25]. Complete response (CR), partial response (PR), and stable disease (SD) were confirmed by a sustained four-week follow-up. Only patients with CR and PR were regarded as responders.

The progression-free survival duration was calculated from the date of initiation of gefitinib treatment to the date of disease progression, death, last follow-up, or the final follow-up day of the study. The overall survival duration after gefitinib was calculated from the date of initiation of gefitinib treatment to the date of death, last follow-up, or the final follow-up day of the study.

Sequencing of EGFR Exons 18–21
Tumor specimens, including frozen tissues or paraffin blocks, were collected. DNA was derived from tumors embedded in paraffin blocks using the QIAmp DNA Mini Kit (Qiagen, Valencia, CA) for EGFR mutation analysis as described previously [26]. The tyrosine kinase domain of the EGFR coding sequence, exons 18, 19, 20 and 21, was amplified by independent polymerase chain reaction (PCR) amplifications.

RNA was extracted from frozen tissue with a QIAmp RNA Mini Kit (Qiagen) according to the manufacturer's protocol. Spectrophotometry was used to measure the amount of extracted RNA, according to the protocol of Mitsudomi, [9]. Exons 18–21 of the EGFR gene were amplified from cDNA with the forward primer 5'-AGCTTGTGGAGCCTCTTACACC-3' and the reverse primer 5'-TAAAATTGATTCCAATGCCATCC-3'. A Qiagen OneStep reverse transcription (RT)-PCR kit (Qiagen) was used for the RT-PCR, as described previously [9].

PCR amplicons were sequenced with an ABI PRISM 3100 (Applied Biosystems, Foster City, CA) in both the sense and antisense directions. Specimens with EGFR mutations were confirmed twice. Only specimens with the same results identified in both rounds were recorded as mutation-positive. Mutations were also checked against the single nucleotide polymorphism database. The single-site EGFR mutations in-frame del-19 or point mutation L858R in exon 21 were defined as classical mutations. Other mutations were infrequently detected, and were defined as nonclassical EGFR mutations. When two or more concomitant different EGFR mutations were detected, the mutation types were defined as complex EGFR mutations. The term "classical mutation pattern" was used when the complex EGFR mutation had either an in-frame del-19 or a point mutation L858R in exon 21.

Statistical Analysis
All of the categorical variables were analyzed with Fisher's exact test because of the small study size. A univariate analysis of the patient characteristics was used for the predictive factor of EGFR TKI response. The overall survival curve and progression-free survival curve were plotted using the Kaplan–Meier method and compared by a log-rank test. Two-sided p-values <.05 were considered significant. All analyses were performed using SPSS software (version 13.0 for Windows; SPSS Inc., Chicago, IL).

	RESULTS

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Clinical Characteristics and EGFR Mutations of Lung Adenocarcinoma Patients
A total of 725 NSCLC patients received gefitinib treatment between June 2004 and October 2007. Specimens from 339 lung adenocarcinoma patients who had measurable disease and received gefitinib therapy for stage IIIb or IV lung adenocarcinoma were collected for EGFR sequencing. Five patients' tissue samples were inadequate for EGFR sequencing.

Finally, 334 gefitinib-treated patients (124 men and 210 women) provided EGFR mutation data. Among them, 211 patients had tumors harboring EGFR mutations (63.2%, 211 of 334). One hundred sixty-eight patients had tumors with classical mutations (83 with del-19 and 85 with L858R), and 43 patients had tumors with nonclassical EGFR mutations, including complex EGFR mutations. These patients have been reported in our previous studies [16, 17, 26–28]. In the present study, we update the follow-up data and focus on those patients who had complex mutations.

Clinical Characteristics and EGFR Mutations of Lung Adenocarcinoma Patients with Complex EGFR Mutation Patterns
Because patients with T790M mutations have been shown to have a high resistance to EGFR TKIs [23, 29, 30], three patients with T790M were excluded from this study. There was a total of 19 lung adenocarcinoma patients who had undergone gefitinib treatment and had complex EGFR mutations (Tables 1 and 2). The median age at which lung cancer was diagnosed was 62.8 years (range, 45.5–78.3 years), with four smokers and 15 nonsmokers. The distribution of lung cancer stages was one stage IIIA patient, one stage IIIB patient, and 17 stage IV patients. The patient with stage IIIA refused surgical treatment and took systemic chemotherapy according to patient preference. Twelve patients had the classical mutation pattern of L858R or del-19. No concurrent del-19 and L858R mutations were observed.

Among the 19 patients, 12 had the classical mutation pattern. There were no differences in gender, smoking status, age (65 or <65 years), lung cancer stage, and prior chemotherapy use between patients with complex EGFR mutations with the classical mutation pattern and those with complex EGFR mutations without the classical mutation pattern. Patients with the classical mutation pattern had a higher gefitinib response rate (83%, 10 of 12) than those without the classical mutation pattern (29%, 2 of 7) (p = .045) (Table 2).

	PROGRESSION-FREE SURVIVAL AND OVERALL SURVIVAL AFTER EGFR TKI TREATMENT

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Patients with nonclassical EGFR mutations (n = 43) had a lower gefitinib response rate (44% [19 of 43] versus 73% [122 of 168]; p < .001), shorter progression-free survival time (median, 4.8 months versus 8.1 months; p = .009), and shorter overall survival (median, 13.5 months versus 16.4 months; p = .239) than patients with classical EGFR mutations (n = 168).

Among the 19 patients with complex EGFR mutations, the median progression-free survival and overall survival times after gefitinib treatment were 8.1 months (95% confidence interval [CI], 4.2–12.0 months) and 22.4 months (95% CI, 8.4–36.4 months), respectively.

Patients with complex mutations with the classical mutation pattern had a longer progression-free survival time than those without the classical mutation pattern (median, 12.7 months; 95% CI, 3.4–22.0 months versus. 4.9 months; 95% CI, 1.5–8.3 months; p = .048, by the log-rank test) (Fig. 1A). Patients with complex mutations with the classical mutation pattern also had a longer overall survival time after gefitinib treatment than those without the classical mutation pattern (median, 24.7 months; 95% CI, 13.0–36.4 months versus 12.3 months; 95% CI, 4.5–20.1 months; p = .027, by the log-rank test) (Fig. 1B).

View larger version (18K): [in this window] [in a new window]   Figure 1. Kaplan–Meier survival curve of progression-free survival (A) and overall survival (B) after gefitinib treatment in gefitinib-treated adenocarcinoma patients with complex epidermal growth factor receptor (EGFR) mutations with the classical mutation pattern (solid line) and without the classical mutations pattern (dashed). Differences in progression-free survival and overall survival between patients with complex EGFR mutations with and without the classical mutation pattern were statistically significant (p = .048 and p = .027, respectively, by the log-rank test).

	DISCUSSION

Top Abstract Introduction Materials and Methods Results Progression-Free Survival and... Discussion Conclusion Author Contributions References

 
Prior studies on EGFR mutations in NSCLC patients have mostly shown single EGFR mutations and very few complex EGFR mutations. The responses to EGFR TKIs in these patients were not clear. Here, we demonstrate the characteristics of 19 lung adenocarcinoma patients with complex EGFR mutations and their responses to gefitinib. Patients with complex EGFR mutations with the classical mutation pattern had the same response rate, progression-free survival time, and overall survival time as those with single classical mutations. Patients with complex EGFR mutations with the classical mutation pattern had a better response to gefitinib than those without the classical mutation pattern. Longer progression-free survival and overall survival times after gefitinib therapy were also noted in patients with the classical mutation pattern.

The present study is the first to determine and assert that patients with complex EGFR mutations with the classical mutation pattern (excluding those with T790M) have the same response rate, progression-free survival time, and overall survival time as patients with single classical mutations (L858R or del-19) after gefitinib treatment. The response rate to gefitinib, 63% (12 of 19), in the patients with complex mutations is also similar to that in patients with single EGFR mutations in other studies [31, 32]. Among the patients with single classical mutations (L858R or del-19), Takano et al. [32] and Riely et al. [33] also showed a progression-free survival duration of 12 months and a median survival time of 20 months. Their survival data were similar to those from patients with complex mutations with the classical mutation pattern in our study. Therefore, the addition of a second mutation, other than T790M, to and exon 19 deletion or L858R substitution does not alter the sensitivity to EGFR TKIs, and it is reasonable to suggest that patients with complex EGFR mutations with the classical mutation pattern can still benefit from gefitinib.

Complex EGFR mutations can appear before treatment [7, 8, 13] or be induced by TKI sequentially [21–23]. For example, a novel high resistance mutation, T790M, is an acquired mutation after EGFR TKI treatment [22, 23]. However, a primary somatic mutation of T790M has also been found [30]. Complex EGFR mutations change not only the amino acid sequence but also the molecular conformation. The characteristics of the biological properties related to complex EGFR mutations have not yet been clarified.

Chen et al. [34] used the H1299 cell line stably transfected with various EGFR mutant constructs. They showed that different complex EGFR mutations had different gefitinib responsiveness in engineered cell line studies, but in vitro biochemical and growth inhibition cannot be extrapolated to in vivo tumor response in patients.

In a review of the English medical literature up to 2007, there was a total of 216 papers on "gefitinib" and "EGFR mutation" and 146 papers on "erlotinib" and "EGFR mutation." We collected data on lung adenocarcinoma patients with complex EGFR mutations from these published reports. Moreover, the patients had records on their response to gefitinib or erlotinib. Consistently, the enrolled patient number was relatively small in each report (Table 3). A total of 34 lung adenocarcinoma patients could be included from the published data, and two of the 34 were treated with erlotinib. Different responses to EGFR TKIs were noted with different complex EGFR mutations. There were 19 patients with a PR to EGFR TKIs, one with a CR, and one with a serum response (SR). There were seven patients who had PD despite EGFR TKIs.

Our study had the largest group of patients with complex EGFR mutations. After combining all 34 patients with complex EGFR mutations from the other studies and the present study, there was a total of 53 lung adenocarcinoma patients with complex EGFR mutations. There were some common complex mutations among the 53 patients, such as three with V765M, L798H, K806E, and L814P; three with del-19 and L861Q; two with del-19 and L858R; two with L858R and R776H; two with L858R and S768I; two with L858R and G779S; and two with G719C and S768I (Table 4). Patients with all the above complex EGFR mutations had good responses (CR, PR, or SR) to EGFR TKIs. Among the three patients with del-19 plus L861Q, two had a PR to gefitinib and one had SD with erlotinib [38]. Patients with the other common complex mutations, including two with L858R plus D761Y and two with L858R plus H850D, had SD or PD with EGFR TKIs. D761Y has been reported as a secondary resistance mutation, like T790M, to EGFR TKIs [39]. It would be interesting to verify whether patients with H850D also have a high resistance to EGFR TKIs. Two patients with G719A plus S768I had different maximum responses to EGFR TKIs. One patient had a PR, whereas the other had PD. A similar condition was also noted in two patients with G719S plus L861Q.

Although our study had the largest group of patients with complex EGFR mutations, it had limitations in that the sample size was still too small to draw any firm conclusions because we were comparing two groups of 12 and seven patients. Even after adding the data from the other studies, there are still limitations in the analysis because of the different tissue sampling methods and treatment response criteria.

	CONCLUSION

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We demonstrated a larger series of lung adenocarcinoma patients with complex EGFR mutations. Patients with complex EGFR mutations with the classical mutation pattern had a better response, longer survival time, and longer progression-free survival time after EGFR TKI therapy than those without the classical mutation pattern. EGFR TKIs may still be the best choice of treatment for these patients.

	AUTHOR CONTRIBUTIONS

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Conception/design: Shang-Gin Wu, Jenn-Yu Wu, Jin-Yuan Shih

Administrative support: Yih-Leong Chang, Jenn-Yu Wu, Jin-Yuan Shih, Pan-Chyr Yang

Provision of study materials: Yih-Leong Chang, Chi-Hsin Yang, Chong-Jen Yu, Meng-Feng Tsai, Jin-Yuan Shih

Collection/assembly of data: Shang-Gin Wu, Jin-Yuan Shih

Data analysis: Shang-Gin Wu, Ya-Chieh Hsu, Jin-Yuan Shih

Manuscript writing: Shang-Gin Wu, Jin-Yuan Shih

Final approval of manuscript: Shang-Gin Wu, Yih-Leong Chang, Ya-Chieh Hsu, Jenn-Yu Wu, Chi-Hsin Yang, Chong-Jen Yu, Meng-Feng Tsai, Jin-Yuan Shih, Pan-Chyr Yang

	ACKNOWLEDGMENTS

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This study was supported by a research grant from the National Science Council, Taiwan (NSC-95-2314-B-002-110-MY3). The authors would like to thank Dr. Gene Alzona Nisperos and Dr. Malcolm Higgins for editing this manuscript. The authors also thank the Department of Medical Research in the National Taiwan University Hospital and NTU Center for Genomic Medicine, National Taiwan University College of Medicine.

	REFERENCES

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1. Davies RL, Grosse VA, Kucherlapati R et al. Genetic analysis of epidermal growth factor action: Assignment of human epidermal growth factor receptor gene to chromosome 7. Proc Natl Acad Sci U S A 1980;77:4188–4192.[Abstract/Free Full Text]
2. Scagliotti GV, Selvaggi G, Novello S et al. The biology of epidermal growth factor receptor in lung cancer. Clin Cancer Res 2004;10:4227s–4232s.[CrossRef][Medline]
3. Sharma SV, Bell DW, Settleman J et al. Epidermal growth factor receptor mutations in lung cancer. Nat Rev Cancer 2007;7:169–181.[CrossRef][Medline]
4. Kris MG, Natale RB, Herbst RS et al. Efficacy of gefitinib, an inhibitor of the epidermal growth factor receptor tyrosine kinase, in symptomatic patients with non-small cell lung cancer: A randomized trial. JAMA 2003;290:2149–2158.[Abstract/Free Full Text]
5. Fukuoka M, Yano S, Giaccone G et al. Multi-institutional randomized phase II trial of gefitinib for previously treated patients with advanced non-small-cell lung cancer (The IDEAL 1 Trial) [corrected]. J Clin Oncol 2003;21:2237–2246.[Abstract/Free Full Text]
6. Amann J, Kalyankrishna S, Massion PP et al. Aberrant epidermal growth factor receptor signaling and enhanced sensitivity to EGFR inhibitors in lung cancer. Cancer Res 2005;65:226–235.[Abstract/Free Full Text]
7. Lynch TJ, Bell DW, Sordella R et al. Activating mutations in the epidermal growth factor receptor underlying responsiveness of non-small-cell lung cancer to gefitinib. N Engl J Med 2004;350:2129–2139.[Abstract/Free Full Text]
8. Paez JG, Jänne PA, Lee JC et al. EGFR mutations in lung cancer: Correlation with clinical response to gefitinib therapy. Science 2004;304:1497–1500.[Abstract/Free Full Text]
9. Mitsudomi T, Kosaka T, Endoh H et al. Mutations of the epidermal growth factor receptor gene predict prolonged survival after gefitinib treatment in patients with non-small-cell lung cancer with postoperative recurrence. J Clin Oncol 2005;23:2513–2520.[Abstract/Free Full Text]
10. Pao W, Miller V, Zakowski M et al. EGF receptor gene mutations are common in lung cancers from "never smokers" and are associated with sensitivity of tumors to gefitinib and erlotinib. Proc Natl Acad Sci U S A 2004;101:13306–13311.[Abstract/Free Full Text]
11. Yatabe Y, Mitsudomi T. Epidermal growth factor receptor mutations in lung cancers. Pathol Int 2007;57:233–244.[CrossRef][Medline]
12. Gu D, Scaringe WA, Li K et al. Database of somatic mutations in EGFR with analyses revealing indel hotspots but no smoking-associated signature. Hum Mutat 2007;28:760–770.[CrossRef][Medline]
13. Shigematsu H, Lin L, Takahashi T et al. Clinical and biological features associated with epidermal growth factor receptor gene mutations in lung cancers. J Natl Cancer Inst 2005;97:339–346.[Abstract/Free Full Text]
14. Huang SF, Liu HP, Li LH et al. High frequency of epidermal growth factor receptor mutations with complex patterns in non-small cell lung cancers related to gefitinib responsiveness in Taiwan. Clin Cancer Res 2004;10:8195–8203.[Abstract/Free Full Text]
15. Tokumo M, Toyooka S, Kiura K et al. The relationship between epidermal growth factor receptor mutations and clinicopathologic features in non-small cell lung cancers. Clin Cancer Res 2005;11:1167–1173.[Abstract/Free Full Text]
16. Yang CH, Yu CJ, Shih JY et al. Specific EGFR mutations predict treatment outcome of stage IIIB/IV patients with chemotherapy-naive non-small-cell lung cancer receiving first-line gefitinib monotherapy. J Clin Oncol 2008;26:2745–2753.[Abstract/Free Full Text]
17. Wu JY, Wu SG, Yang CH et al. Lung cancer with epidermal growth factor receptor exon 20 mutations is associated with poor gefitinib treatment response. Clin Cancer Res 2008;14:4877–4882.[Abstract/Free Full Text]
18. Greulich H, Chen TH, Feng W et al. Oncogenic transformation by inhibitor-sensitive and -resistant EGFR mutants. PLoS Med 2005;2:e313.[CrossRef][Medline]
19. Chen Z, Feng J, Saldivar JS et al. EGFR somatic doublets in lung cancer are frequent and generally arise from a pair of driver mutations uncommonly seen as singlet mutations: One-third of doublets occur at five pairs of amino acids. Oncogene 2008;27:4336–4343.[Medline]
20. Hsieh MH, Fang YF, Chang WC et al. Complex mutation patterns of epidermal growth factor receptor gene associated with variable responses to gefitinib treatment in patients with non-small cell lung cancer. Lung Cancer 2006;53:311–322.[CrossRef][Medline]
21. Zhang GC, Lin JY, Wang Z et al. Epidermal growth factor receptor double activating mutations involving both exons 19 and 21 exist in Chinese non-small cell lung cancer patients. Clin Oncol (R Coll Radiol) 2007;19:499–506.[Medline]
22. Pao W, Miller VA, Politi KA et al. Acquired resistance of lung adenocarcinomas to gefitinib or erlotinib is associated with a second mutation in the EGFR kinase domain. PLoS Med 2005;2:e73.[CrossRef][Medline]
23. Kobayashi S, Boggon TJ, Dayaram T et al. EGFR mutation and resistance of non-small-cell lung cancer to gefitinib. N Engl J Med 2005;352:786–792.[Abstract/Free Full Text]
24. Travis WDBE, Muller-Hermelink HK, Harris CC. Pathology and Genetics of Tumors of the Lung, Pleura, Thymus and Heart. Lyon, France: IARC Press, 2004.
25. Therasse P, Arbuck SG, Eisenhauer EA et al. New guidelines to evaluate the response to treatment in solid tumors. European Organization for Research and Treatment of Cancer, National Cancer Institute of the United States, National Cancer Institute of Canada. J Natl Cancer Inst 2000;92:205–216.[Abstract/Free Full Text]
26. Shih JY, Gow CH, Yu CJ et al. Epidermal growth factor receptor mutations in needle biopsy/aspiration samples predict response to gefitinib therapy and survival of patients with advanced nonsmall cell lung cancer. Int J Cancer 2006;118:963–969.[CrossRef][Medline]
27. Wu SG, Gow CH, Yu CJ et al. Frequent epidermal growth factor receptor gene mutations in malignant pleural effusion of lung adenocarcinoma. Eur Respir J 2008;32:924–930.[Abstract/Free Full Text]
28. Wu JY, Yu CJ, Yang CH et al. First- or second-line therapy with gefitinib produces equal survival in non-small cell lung cancer. Am J Respir Crit Care Med 2008;178:847–853.[Abstract/Free Full Text]
29. Kosaka T, Yatabe Y, Endoh H et al. Mutations of the epidermal growth factor receptor gene in lung cancer: Biological and clinical implications. Cancer Res 2004;64:8919–8923.[Abstract/Free Full Text]
30. Shih JY, Gow CH, Yang PC. EGFR mutation conferring primary resistance to gefitinib in non-small-cell lung cancer. N Engl J Med 2005;353:207–208.[Free Full Text]
31. Han SW, Kim TY, Hwang PG et al. Predictive and prognostic impact of epidermal growth factor receptor mutation in non-small-cell lung cancer patients treated with gefitinib. J Clin Oncol 2005;23:2493–2501.[Abstract/Free Full Text]
32. Takano T, Ohe Y, Sakamoto H et al. Epidermal growth factor receptor gene mutations and increased copy numbers predict gefitinib sensitivity in patients with recurrent non-small-cell lung cancer. J Clin Oncol 2005;23:6829–6837.[Abstract/Free Full Text]
33. Riely GJ, Pao W, Pham D et al. Clinical course of patients with non-small cell lung cancer and epidermal growth factor receptor exon 19 and exon 21 mutations treated with gefitinib or erlotinib. Clin Cancer Res 2006;12:839–844.[Abstract/Free Full Text]
34. Chen YR, Fu YN, Lin CH et al. Distinctive activation patterns in constitutively active and gefitinib-sensitive EGFR mutants. Oncogene 2006;25:1205–1215.[CrossRef][Medline]
35. Miller AB, Hoogstraten B, Staquet M et al. Reporting results of cancer treatment. Cancer 1981;47:207–214.[CrossRef][Medline]
36. Green S, Weiss GR. Southwest Oncology Group standard response criteria, endpoint definitions and toxicity criteria. Invest New Drugs 1992;10:239–253.[CrossRef][Medline]
37. Costa DB, Schumer ST, Tenen DG et al. Differential responses to erlotinib in epidermal growth factor receptor (EGFR)-mutated lung cancers with acquired resistance to gefitinib carrying the L747S or T790M secondary mutations. J Clin Oncol 2008;26:1182–1184; author reply 1184–1186.[Free Full Text]
38. Jackman DM, Yeap BY, Lindeman NI et al. Phase II clinical trial of chemotherapy-naive patients 70 years of age treated with erlotinib for advanced non-small-cell lung cancer. J Clin Oncol 2007;25:760–766.[Abstract/Free Full Text]
39. Balak MN, Gong Y, Riely GJ et al. Novel D761Y and common secondary T790M mutations in epidermal growth factor receptor-mutant lung adenocarcinomas with acquired resistance to kinase inhibitors. Clin Cancer Res 2006;12:6494–6501.[Abstract/Free Full Text]
40. Kwak EL, Sordella R, Bell DW et al. Irreversible inhibitors of the EGF receptor may circumvent acquired resistance to gefitinib. Proc Natl Acad Sci U S A 2005;102:7665–7670.[Abstract/Free Full Text]
41. Godin-Heymann N, Ulkus L, Brannigan BW et al. The T790M "gatekeeper" mutation in EGFR mediates resistance to low concentrations of an irreversible EGFR inhibitor. Mol Cancer Ther 2008;7:874–879.[Abstract/Free Full Text]
42. Li D, Ambrogio L, Shimamura T et al. BIBW2992, an irreversible EGFR/HER2 inhibitor highly effective in preclinical lung cancer models. Oncogene 2008;27:4702–4711.[CrossRef][Medline]
43. Han SW, Kim TY, Jeon YK et al. Optimization of patient selection for gefitinib in non-small cell lung cancer by combined analysis of epidermal growth factor receptor mutation, K-ras mutation, and Akt phosphorylation. Clin Cancer Res 2006;12:2538–2544.[Abstract/Free Full Text]
44. Asahina H, Yamazaki K, Kinoshita I et al. Non-responsiveness to gefitinib in a patient with lung adenocarcinoma having rare EGFR mutations S768I and V769L. Lung Cancer 2006;54:419–422.[CrossRef][Medline]
45. Ichihara S, Toyooka S, Fujiwara Y et al. The impact of epidermal growth factor receptor gene status on gefitinib-treated Japanese patients with non-small-cell lung cancer. Int J Cancer 2007;120:1239–1247.[CrossRef][Medline]
46. Taron M, Ichinose Y, Rosell R et al. Activating mutations in the tyrosine kinase domain of the epidermal growth factor receptor are associated with improved survival in gefitinib-treated chemorefractory lung adenocarcinomas. Clin Cancer Res 2005;11:5878–5885.[Abstract/Free Full Text]
47. Tokumo M, Toyooka S, Ichihara S et al. Double mutation and gene copy number of EGFR in gefitinib refractory non-small-cell lung cancer. Lung Cancer 2006;53:117–121.[CrossRef][Medline]
48. Chou TY, Chiu CH, Li LH et al. Mutation in the tyrosine kinase domain of epidermal growth factor receptor is a predictive and prognostic factor for gefitinib treatment in patients with non-small cell lung cancer. Clin Cancer Res 2005;11:3750–3757.[Abstract/Free Full Text]
49. van Zandwijk N, Mathy A, Boerrigter L et al. EGFR and KRAS mutations as criteria for treatment with tyrosine kinase inhibitors: Retro- and prospective observations in non-small-cell lung cancer. Ann Oncol 2007;18:99–103.[Abstract/Free Full Text]
50. Pallis AG, Voutsina A, Kalikaki A et al. ‘Classical’ but not ‘other’ mutations of EGFR kinase domain are associated with clinical outcome in gefitinib-treated patients with non-small cell lung cancer. Br J Cancer 2007;97:1560–1566.[CrossRef][Medline]
51. Kosaka T, Yatabe Y, Endoh H et al. Analysis of epidermal growth factor receptor gene mutation in patients with non-small cell lung cancer and acquired resistance to gefitinib. Clin Cancer Res 2006;12:5764–5769.[Abstract/Free Full Text]
52. Choong NW, Dietrich S, Seiwert TY et al. Gefitinib response of erlotinib-refractory lung cancer involving meninges—role of EGFR mutation. Nat Clin Pract Oncol 2006;3:50–57; quiz 51 p following 57.[CrossRef][Medline]
53. Pugh TJ, Bebb G, Barclay L et al. Correlations of EGFR mutations and increases in EGFR and HER2 copy number to gefitinib response in a retrospective analysis of lung cancer patients. BMC Cancer 2007;7:128.[CrossRef][Medline]
54. Kimura H, Suminoe M, Kasahara K et al. Evaluation of epidermal growth factor receptor mutation status in serum DNA as a predictor of response to gefitinib (IRESSA). Br J Cancer 2007;97:778–784.[CrossRef][Medline]
55. Oshita F, Matsukuma S, Yoshihara M et al. Novel heteroduplex method using small cytology specimens with a remarkably high success rate for analysing EGFR gene mutations with a significant correlation to gefitinib efficacy in non-small-cell lung cancer. Br J Cancer 2006;95:1070–1075.[CrossRef][Medline]

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