Polymerase Chain Reaction Clamp Method Research Articles

Characteristics and prognostic analysis of patients with detected KRAS mutations in resected lung adenocarcinomas by peptide nucleic acid-locked nucleic acid polymerase chain reaction (PNA-LNA PCR) clamp method.

Kirsten rat sarcoma virus (KRAS) gene mutations are a type of driver mutation discovered in the 1980s, but for a long time no molecular targeted drugs were available for them. Recently, sotorasib was developed as a molecular targeted drug for KRAS mutations. It is therefore necessary to identify the characteristics of patients with KRAS mutations. This was the single-institution retrospective study. Surgically resected tumors from lung adenocarcinoma patients were collected at a single institution from June 2016 to September 2019. Peptide nucleic acid-locked nucleic acid polymerase chain reaction (PNA-LNA PCR) clamp analysis of KRAS G12X mutations was compared with analysis by therascreen KRAS RGQ kit. The association between KRAS mutation status and patient characteristics and prognosis was assessed. Among 499 lung adenocarcinomas, KRAS mutations were evaluated in 197 cases, excluding stage IV lung cancer and tumors with epidermal growth factor receptor (EGFR) and anaplastic lymphoma kinase (ALK) mutations. KRAS G12X mutations were detected in 59 cases (29.9%). The highest frequency by gene mutation subtype was G12V in 23 cases (39.0%), followed by G12C in 16 cases (27.1%), G12D in 12 cases (20.3%), G12S in 4 cases (6.8%) and G12A in 2 cases. For the G12C mutation, the PNA-LNA PCR clamp and therascreen methods were consistent, but for the G12D and G12S mutations, the PNA-LNA PCR clamp method showed higher detection rates. In operable tumors, G12C mutations were more frequent in males, smokers, and patients with high expression of programmed death-ligand 1 (PD-L1), and had no correlation with prognosis. By the PNA-LNA PCR clamp method, G12C mutation of surgical specimens was detected successfully. The PNA-LNA PCR clamp method is expected to be applied to the detection of druggable G12C mutations.

Epidermal growth factor receptor mutations in adenocarcinoma in situ and minimally invasive adenocarcinoma detected using mutation-specific monoclonal antibodies

ObjectivesEpidermal growth factor receptor (EGFR) mutation rates in adenocarcinoma in situ (AIS) and minimally invasive adenocarcinoma (MIA) were studied using both DNA analysis and mutation-specific immunohistochemistry. Materials and methodsThe peptide nucleic acid-locked nucleic acid polymerase chain reaction clamp method was used to detect mutations in exons 18, 19, 20, and 21 of the EGFR gene in DNA samples extracted from paraffin-embedded tissue sections. Simultaneously, immunohistochemical analysis with two EGFR mutation-specific monoclonal antibodies was used to identify proteins resulting from an in-frame deletion in exon 19 (E746_A750del) and a point mutation replacing leucine with arginine at codon 858 of exon 21 (L858R). ResultsForty-three tumors (22 AIS and 21 MIA) were examined. The EGFR mutation rate in AIS detected by DNA analysis was 27.3% (L858R, 5/22; exon 19 deletion,1/22), whereas that detected in MIA was 42.9% (L858R,4/21; exon 19 deletion,5/21). Mutations detected by immunohistochemical analysis included 22.7% (L858R, 4/22; exon 19 deletion, 1/22) in AIS and 42.9% (L858R, 4/21; exon 19 deletion, 5/21) in MIA. Although some results were contradictory, concordant results were obtained using both assays in 38 of 43 cases (88.4%). ConclusionDNA and immunohistochemical analyses revealed similar EGFR mutation rates in both MIA and AIS, suggesting that mutation-specific monoclonal antibodies are useful to confirm DNA assay results.

Dynamic Plasma EGFR Mutation Status as a Predictor of EGFR-TKI Efficacy in Patients with EGFR-Mutant Lung Adenocarcinoma

Epidermal growth factor receptor (EGFR) mutation status in lung cancer can effectively predict EGFR-tyrosine kinase inhibitor (TKI) efficacy. We evaluated the role of dynamic plasma cell-free DNA EGFR mutation status in outcome prediction. Advanced lung adenocarcinoma patients were enrolled and prospectively observed for outcomes of EGFR-TKI treatment. Peptide nucleic acid-zip nucleic acid polymerase chain reaction clamp method was developed to assess EGFR mutations in matched tumor and serial plasma cell-free DNA specimens. A total of 72 patients were enrolled in this study, of which 62 patients (86.1%) had EGFR-mutant tumors (34 patients with exon 19 deletions, and 28 patients with L858R). Pretreatment plasma used for EGFR mutation testing showed a sensitivity of 59.7% and a specificity of 100%. Detection sensitivity was significantly higher in stage IV-M1b patients compared with stage IIIb and IV-M1a patients (78.0% versus 23.8%, p < 0.001). All patients who presented with EGFR-mutant tumors received first-line EGFR-TKI therapy. The objective response rate and disease control rate were 74.2% and 82.3%, respectively. Median progression-free survival and overall survival were 8.8 months (95% CI: 6.6-11.0) and 20.5 months (95% CI 15.1-26.0), respectively. Failure to clear plasma EGFR mutations after EGFR-TKI treatment was an independent predictor of lower disease control rate (odds ratio 5.26 [95% CI: 1.13-24.44]; p = 0.034), shorter progression-free survival (hazard ratio: 1.97 [95% CI: 1.33-2.91]; p = 0.001), and shorter overall survival (hazard ratio: 1.82 [95% CI: 1.04-3.18], p = 0.036). Changes in plasma EGFR mutation status can be successfully assessed using the peptide nucleic acid-zip nucleic acid polymerase chain reaction clamp method and can serve as an independent outcome predictor.

Predictive factors in patients with EGFR mutation-negative non-small cell lung cancer treated with erlotinib.

Factors predicting the efficacy of erlotinib treatment in patients with EGFR mutation-negative non-small-cell lung cancer (NSCLC) have not been well studied. This retrospective study investigates whether patient characteristics, such as site of metastasis, can predict the efficacy of erlotinib treatment in NSCLC patients. In total, 53 EGFR mutation-negative NSCLC patients treated with erlotinib were enrolled, and the associations between clinicopathological characteristics and patient survival were analyzed. The EGFR mutation status was determined using the peptide nucleic acid-locked nucleic acid polymerase chain reaction clamp method. Survival curves were obtained using the Kaplan-Meier method. Among the NSCLC patients treated with erlotinib, 27 patients with pulmonary metastasis exhibited significantly longer progression-free survival (PFS) and overall survival (OS) times than those without pulmonary metastasis (median PFS time, 2.9 versus 1.2 months; P=0.0010 and median OS time, 12.4 versus 4.1 months; P=0.0007). Multivariate analyses also revealed that pulmonary metastasis independently correlated with PFS and OS times (hazard ratio, 0.39; P=0.0055 and hazard ratio, 0.33; P=0.0022, respectively). Patients with pulmonary metastasis exhibited significantly longer PFS and OS times than those without pulmonary metastasis. The presence of pulmonary metastasis may be a predictive factor in patients with EGFR mutation-negative NSCLC treated with erlotinib.

Phase II study of erlotinib for previously treated patients with EGFR wild-type non-small-cell lung cancer, following EGFR mutation status reevaluation with the Scorpion Amplified Refractory Mutation System.

While assessing the efficacy of erlotinib in patients with epidermal growth factor receptor (EGFR) wild-type (WT) non-small-cell lung cancer (NSCLC), the sensitivity of the method used for the EGFR mutation analysis may affect the evaluation of the efficacy. We conducted a phase II study of erlotinib for previously treated patients with EGFR WT NSCLC screened by the peptide nucleic acid-locked nucleic acid (PNA-LNA) polymerase chain reaction (PCR) clamp method, which is known to be highly sensitive. The primary endpoint was the objective response rate (ORR). Preplanned reevaluation of the EGFR genotype as an exploratory endpoint was performed using the Scorpion Amplification Refractory Mutation System (S-ARMS) assay. Erlotinib was administered daily until disease progression or development of unacceptable toxicity. A total of 53 evaluable patients were enrolled. The histological subtypes were adenocarcinoma in 40 patients, squamous cell carcinoma in 9 patients and not otherwise specified NSCLC in 4 patients. Partial response (PR) was achieved in 6 patients (4 with adenocarcinoma and 2 with squamous cell carcinoma). The ORR was 11.3% [95% confidence interval (CI): 4.3-23.0]. The median progression-free survival (PFS) was 1.8 months (95% CI: 1.2-2.3). Samples from 26 of the 53 patients (49.0%) were available for EGFR mutation reanalysis with the S-ARMS assay. Of these 26 samples, only 1 sample of adenocarcinoma was found to be EGFR mutation-positive (exon 19 deletion) and the patient achieved a PR. The EGFR WT genotype was reconfirmed by the S-ARMS assay in the remaining 25 patients and 2 of these patients exhibited a PR. This study did not meet the primary endpoint, although erlotinib was found to be moderately effective in pretreated patients with EGFR WT NSCLC, even when the EGFR mutational status was confirmed by the highly sensitive PNA-LNA clamp PCR method.

Rebiopsy of non–small cell lung cancer patients with acquired resistance to epidermal growth factor receptor‐tyrosine kinase inhibitor

The secondary epidermal growth factor receptor (EGFR) mutation Thr790Met (T790M) accounts for approximately half of acquired resistances to EGFR-tyrosine kinase inhibitor (TKI). Recent reports have demonstrated that the emergence of T790M predicts a favorable prognosis and indolent progression. However, rebiopsy to confirm T790M status can be challenging due to limited tissue availability and procedural feasibility, and little is known regarding the differences among patients with or without T790M mutation. The study investigated 78 EGFR-mutant patients who had undergone rebiopsy after TKI failure. The peptide nucleic acid-locked nucleic acid polymerase chain reaction clamp method was used in EGFR mutational analyses. Various patient characteristics and postprogression survivals (PPSs) after initial TKI failure were retrospectively compared in patients with and without T790M. The T790M mutation was identified in 4 (17%) of 24 central nervous system lesions, and in 22 (41%) of 54 other lesions (P = .0417). No other characteristics had a statistical association with T790M prevalence. Median PPS was 31.4 months in 26 patients with T790M, and 11.4 months in 52 patients without T790M (P = .0017). In the multivariate analysis, statistically significant factors for longer PPS included T790M-positive, good performance status, and no carcinomatous meningitis. The emergence of T790M in central nervous system lesions was rare, compared with other lesions. Patients with T790M after TKI failure appear to have better prognoses than those without T790M. TKI rechallenge or continuous administration beyond progression may be effective after initial TKI failure.

Prognostic Value of EGFR Mutation and ERCC1 in Patients with Non-Small Cell Lung Cancer Undergoing Platinum-Based Chemotherapy

BackgroundIn order to improve the outcome of patients with non-small cell lung cancer (NSCLC), a biomarker that can predict the efficacy of chemotherapy is needed. The aim of this study was to assess the role of EGFR mutations and ERCC1 in predicting the efficacy of platinum-based chemotherapy and the outcome of patients with NSCLC.MethodsWe conducted a retrospective study to analyze the relationships between EGFR mutations or ERCC1 expression and progression-free survival (PFS) in patients with NSCLC who received platinum-based chemotherapy. EGFR mutation status was determined using the peptide nucleic acid-locked nucleic acid polymerase chain reaction clamp method, and immunohistochemistry was used to examine the expression of ERCC1 in tumor samples obtained from the patients.ResultsAmong the NSCLC patients who received platinum-based chemotherapy, the median PFS was significantly better in those who had never smoked and those with exon 19 deletion, and the median overall survival (OS) was significantly better in those who had never smoked, those with exon 19 deletion, and women. Cox regression analysis revealed that exon 19 deletion and having never smoked were significantly associated with both PFS and OS. Subset analysis revealed a significant correlation between ERCC1 expression and EGFR mutation, and ERCC1-negative patients with exon 19 deletion had a longer PFS than the other patients; ERCC1-positive patients without exon 19 deletion had a shorter PFS than the other patients.ConclusionsOur results indicate that among NSCLC patients receiving platinum-based chemotherapy, those with exon 19 deletion have a longer PFS and OS. Our findings suggest that platinum-based chemotherapy is more effective against ERCC1-negative and exon 19-positive NSCLC.

Preexisting interstitial lung disease is inversely correlated to tumor epidermal growth factor receptor mutation in patients with lung adenocarcinoma

IntroductionInterstitial lung disease (ILD), especially idiopathic pulmonary fibrosis, has been shown to be associated with lung carcinogenesis. However, an association between epidermal growth factor receptor (EGFR) mutation status and preexisting ILD in patients with lung adenocarcinoma is unknown. MethodsBetween January 2008 and April 2012, we analyzed 602 patients with lung adenocarcinoma. EGFR mutation status was analyzed using the peptide nucleic acid-locked nucleic acid polymerase chain reaction clamp method, and preexisting ILD was diagnosed based on clinical features, chest high-resolution computed tomography (HRCT) findings, and histological findings. ResultsThere were 555 patients with pulmonary adenocarcinoma with tumor EGFR mutation data available for analysis. Of them, 31 patients (6%) had preexisting ILD, and EGFR mutations were detected in 246 of the 555 patients (46%). In the comparison between patients with EGFR mutations and those with wild-type EGFR, there was a significant inverse association between occurrence of tumors with EGFR mutations and ILD (1/246 vs. 30/309, P<0.001). Based on the multivariate analysis of age, gender, smoking status, Eastern Cooperative Oncology Group Performance Status, stage, and ILD, EGFR mutations were found to be independently associated with females (OR, 1.58; 95% CI, 1.01–2.46; P=0.048), never-smokers (OR, 3.31; 95% CI, 2.12–5.20; P<0.001), and the absence of ILD (OR, 17.41; 95% CI, 3.54–315.34; P<0.001). ConclusionsThis study showed that patients with pulmonary adenocarcinoma and ILD had a lower probability of carrying tumor EGFR mutations.

How Sensitive Are Epidermal Growth Factor Receptor–Tyrosine Kinase Inhibitors for Squamous Cell Carcinoma of the Lung Harboring EGFR Gene–Sensitive Mutations?

Epidermal growth factor receptor (EGFR) mutations are found mostly in adenocarcinoma, and rarely in squamous cell carcinoma (SQC). Little is known about SQC harboring EGFR mutations. Between April 2006 and October 2010, we investigated the incidence of EGFR activating mutations in SQC of the lung using the peptide nucleic acid-locked nucleic acid polymerase chain reaction clamp method. The efficacy of EGFR-tyrosine kinase inhibitors (TKIs) was retrospectively evaluated in patients with EGFR-mutated SQC. Further pathologic analyses were performed using immunohistochemistry. Thirty-three of 249 patients with SQC (13.3%) had EGFR mutations, including exon 19 deletion (19 of 33 patients, 58%), L858R point mutation in exon 21 (12 of 33, 36%), and G719S point mutation in exon 18 (2 of 33, 6%). Twenty of these 33 patients received EGFR-TKI therapy, and five of these 20 responded to EGFR-TKIs with a response rate of 25.0% (95% confidence interval [CI], 8.7%-49.1%). The patients' median progression-free survival and median overall survival were 1.4 months (95% CI, 0.7-5.8 months) and 14.6 months (95% CI, 2.9-undeterminable months), respectively. Approximately one third of the EGFR-mutated SQC patients achieved progression-free survival for longer than 6 months. Some of these patients had high carcinoembryonic antigen levels or a history of never smoking, or were positive for thyroid transcription factor-1. Although EGFR-TKIs seem to be generally less effective in EGFR-mutated SQC than in EGFR-mutated adenocarcinoma, some EGFR-mutated SQC patients can obtain clinical benefit from EGFR-TKIs. To better identify these patients, not only EGFR mutation status, but also clinical factors and pathologic findings should be taken into consideration.

Heterogeneity of the EGFR mutation status between the primary tumor and metastatic lymph node and the sensitivity to EGFR tyrosine kinase inhibitor in non-small cell lung cancer

The purpose of this study was to clarify the distribution of epidermal growth factor receptor (EGFR) mutations between primary tumors (PT) and metastatic lymph node (MLN) in patients with resected non-small cell lung cancer (NSCLC) and to identify a better predictive marker of the response to EGFR tyrosine kinase inhibitor (EGFR-TKI). We conducted a retrospective review of the data of 70 lung cancer patients with lymph node metastasis who underwent surgical resection. Analysis to detect EGFR mutations was performed by a peptide nucleic acid-locked nucleic acid polymerase chain reaction clamp method. EGFR mutations were detected in 15.7 % of both the PT and MLN and in 14.3 % of the PT only. The response rate to EGFR-TKI tended to be higher in patients with EGFR mutations in the MLN, as all patients with EGFR mutations in the MLN showed disease control to treatment with EGFR-TKI. Our results demonstrated that the EGFR mutation status of MLN is a predictive marker of the response to EGFR-TKI therapy in patients with recurrent NSCLC after surgical resection.

First-Line Gefitinib in Patients Aged 75 or Older With Advanced Non–Small Cell Lung Cancer Harboring Epidermal Growth Factor Receptor Mutations: NEJ 003 Study

Recent studies have demonstrated that first-line treatment with gefitinib, an epidermal growth factor receptor (EFGR)-targeted tyrosine kinase inhibitor, is significantly superior to standard chemotherapy for advanced non-small-cell lung cancer (NSCLC) harboring EGFR sensitive mutations. Meanwhile, the efficacy of gefitinib therapy among elderly populations diagnosed with EGFR-mutated NSCLC has not yet been elucidated. The purpose of this study was to investigate the efficacy and feasibility of gefitinib for chemotherapy-naive patients aged 75 or older with NSCLC harboring EGFR mutations; generally, these patients have no indication for treatment with platinum doublets. Chemotherapy-naive patients aged 75 years or older with performance status 0 to 1 and advanced NSCLC harboring EGFR mutations, as determined by the peptide nucleic acid-locked nucleic acid polymerase chain reaction clamp method, were enrolled. The enrolled patients received 250 mg/day of gefitinib orally. Between January 2008 and May 2009, 31 patients were enrolled, all of whom were eligible. The median age was 80 (range, 75-87) years. Twenty-five patients (81%) were women, and 30 patients (97%) had adenocarcinoma. The overall response rate was 74% (95% confidence interval, 58%-91%), and the disease control rate was 90%. The median progression-free survival was 12.3 months. The common adverse events were rash, diarrhea, and liver dysfunction. One treatment-related death because of interstitial lung disease occurred. This is the first study that verified safety and efficacy of first-line treatment with gefitinib in elderly patients having advanced NSCLC with EGFR mutation. Considering its strong antitumor activity and mild toxicity, first-line gefitinib may be preferable to standard chemotherapy for this population.

1323 - Study of the Safety and Efficacy of Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitors in 97 Patients with Epidermal Growth Factor Receptor Mutation-Positive Non-Small Cell Lung Cancer

ABSTRACT Background Recent phase 3 trials have demonstrated that first-line epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) improved the progression-free survival (PFS) in good performance status (PS) patients with non-small cell lung cancer (NSCLC) harboring activating EGFR mutations. We aimed to study the safety and efficacy of EGFR TKIs in patients with activating EGFR mutation-positive NSCLC in a normal clinical setting. Materials and methods Between August 2006 and October 2011, 487 patients with NSCLC were examined for EGFR mutations by the peptide nucleic acid–locked nucleic acid polymerase chain reaction clamp method at Toranomon Hospital. One hundred and forty-two patients were tested positive for EGFR mutations: 82 patients had exon 19 deletions and 60 patients had L858R mutations in exon 21. Of these 142 patients, EGFR TKIs were administered in 97 patients (51 men and 46 women, with a median age of 68 years). We retrospectively studied the clinical data to determine the efficacy and toxicity of EGFR TKIs that were administered to these patients. The overall survival and PFS from the start date of EGFR TKI therapy were calculated using the Kaplan–Meier method. Results Thirty-one patients were aged 75 or more. Fourteen patients had a poor PS of 3 or 4 and 57 patients had previously undergone chemotherapy. Gefitinib was administered to 76 patients, erlotinib to 56 patients, and both drugs to 35 patients. The response rate was 49%. The median PFS was 10.6 months and the median survival time was 26.4 months. The following grade 3 or 4 toxicities were observed: skin rash (n = 6), increased aminotransferase levels (n = 4), and interstitial lung disease (n = 6). Conclusion Although patients who are elderly, those with poor PS, and those who had previously undergone chemotherapy were included in this study, EGFR TKIs for 97 patients with EGFR mutation-positive NSCLC in clinical practice showed a median PFS of 10.6 months and a median survival time of 26.4 months without treatment-related death. The results of this study were consistent with those of the recent phase 3 trials. Disclosure All authors have declared no conflicts of interest.

The Peptide Nucleic Acid-Locked Nucleic Acid Polymerase Chain Reaction Clamp-Based Test for Epidermal Growth Factor Receptor Mutations in Bronchoscopic Cytological Specimens of Non-Small Cell Lung Cancer

Objectives: Cytological examination of samples obtained by bronchoscopy is a useful method for establishing the diagnosis of non-small cell lung cancer (NSCLC). However, the utility of a highly sensitive method for the detection of epidermal growth factor receptor (EGFR) mutation in the cytological specimens has not been fully evaluated. Methods: We retrospectively examined the efficacy of the peptide nucleic acid-locked nucleic acid polymerase chain reaction (PNA-LNA PCR) clamp method for detecting EGFR mutations in 122 bronchoscopic cytological specimens from NSCLC patients. Results: Overall, 41 specimens (33.6%) were positive for EGFR mutation. Twenty-nine (39.7%) of 73 specimens obtained by using endobronchial ultrasonography with a guide sheath, 7 (33.3%) of 21 specimens obtained under direct vision by using a conventional bronchoscope, 4 (36.4%) of 11 specimens obtained by using an ultrathin bronchoscope, and 1 (5.9%) of 17 specimens obtained by endobronchial ultrasound-guided transbronchial needle aspiration were positive for EGFR mutation. Furthermore, among 22 resected NSCLC cases, the EGFR mutation status obtained from bronchoscopic materials was consistent with the status obtained from surgical samples, with the exception of 1 case. Conclusion: The detection of EGFR mutation by subjecting bronchoscopic cytological specimens to a PNA-LNA PCR clamp assay proves useful.

Multigene Mutation Analysis of Metastatic Lymph Nodes in Non-small Cell Lung Cancer Diagnosed by Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration

The importance of biomarker analysis in patients with non-small cell lung cancer (NSCLC) is well known. The purpose of this study was to analyze the mutation status of multiple genes in metastatic lymph nodes obtained by endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) and to examine the correlation between treatments and outcomes. Genetic alterations were analyzed in metastatic hilar or mediastinal lymph nodes diagnosed by EBUS-TBNA in 156 patients with NSCLC. Epidermal growth factor receptor (EGFR) was analyzed using the peptide nucleic acid-locked nucleic acid polymerase chain reaction clamp method (n = 156). V-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (K-ras) (exons 2-3) and tumor protein 53 (p53) (exons 4-8) were analyzed by direct sequencing (n = 113). In addition, retrospective chart review was performed for clinical data analysis. EGFR gene mutations were detected in 42 cases (26.9%). Twenty-three patients with EGFR mutations received gefitinib, with an overall response rate (partial response [PR]) of 54.5% and disease control rate (PR + stable disease) of 86.4% (Response Evaluation Criteria in Solid Tumors). K-ras gene mutations were detected in four cases (3.5%), and p53 gene mutations were detected in 47 cases (41.6%). Fifty-two patients underwent conventional chemotherapy (46 patients underwent platinum-based chemotherapy). Patients with p53 gene mutations showed chemoresistance (progressive disease of 42.9%, P = .0339) and a relatively poor prognosis after chemotherapy (P = .1391). Multigene mutation analysis can be performed in EBUS-TBNA samples of metastatic lymph nodes from patients with NSCLC. EBUS-TBNA allows genetic evaluation of tumor cells within the metastatic node, which may allow physicians to better select treatments, particularly EGFR tyrosine kinase inhibitors.

Clinicopathologic Factors Affecting the Progression-Free Survival of Patients With Advanced Non–Small-Cell Lung Cancer After Gefitinib Therapy

BackgroundThe aim of this study was to analyze the factors independent of epidermal growth factor (EGFR) gene mutations that affect the progression-free survival (PFS) of patients with advanced non–small-cell lung cancer (NSCLC) after gefitinib therapy. Patients and MethodsEighty patients with advanced NSCLC between January 2003 and April 2010 at Kyoto University Hospital were analyzed for EGFR somatic mutations and treated with gefitinib. We adopted the peptide nucleic acid–locked nucleic acid polymerase chain reaction clamp method for determination of EGFR mutation status. To evaluate risk factors associated with PFS, Cox proportional hazards regression model with a step-down procedure was used. Proportional hazards assumptions were checked and satisfied; only those variables with statistically significant results in univariate analysis were included in a multivariate analysis. ResultsThe median PFS of patients with EGFR mutations were significantly longer than in patients with wild-type EGFR. The median PFS of patients after first-line gefitinib therapy was significantly longer than those who received treatment as a second-line therapy. The median PFS of patients over 75 years of age was significantly longer than in younger patients. Based on multivariate analysis, wild-type EGFR status and age < 75 years were significant and independent negative factors that affect PFS after gefitinib therapy. ConclusionIn this study, we showed the EGFR mutants and age > 75 years were good predictive factors for PFS after gefitinib therapy, suggesting that first-line gefitinib treatment for older patients is efficacious regardless of EGFR mutational status.

Complex Mutations in the Epidermal Growth Factor Receptor Gene in Non-small Cell Lung Cancer

Mutation of the epidermal growth factor receptor (EGFR) gene can predict the efficacy of EGFR-tyrosine kinase inhibitors. Different mutations have been shown to co-occur in a single tumor. However, the frequency of these so-called "complex mutations" and the efficacy of gefitinib in treating patients with these mutations are unclear. We investigated the frequency of complex mutations in 783 patients with non-small cell lung cancer seen at our institutes between April 2006 and May 2009. Mutational analysis was performed using the peptide nucleic acid-locked nucleic acid polymerase chain reaction clamp method. Gefitinib efficacy was evaluated in patients found to have complex mutations. EGFR: mutations were detected in 318 (41%) patients, with 21 (6.6%) of these individuals having complex mutations. Sixteen of these 21 patients received gefitinib. The response rate (RR) was 67% (95% confidence interval [CI], 35-90%) and median progression-free survival was 12.2 months (95% CI, 1.3 months to undeterminable). Analysis of RR according to mutation type revealed that patients with deletional mutation in exon 19 (Del-19) and a point mutation in exon 21 (L858R) had a better RR (86%, 6 of 7) than those with other complex mutation patterns such as a point mutation in exon 18 (G719S) + L858R (40%, 2 of 5) (p = 0.2222). The median progression-free survival was also longer in these patients (16.5 months; 95% CI, 1.1 months to undeterminable versus 3.8 months; 95% CI, 0.7-10.0 months) (p = 0.0459). Complex EGFR mutations are not rare. Gefitinib has different efficacy according to the type of complex EGFR mutations. Patients with Del-19 and L858R mutations may benefit more from gefitinib than other types of complex mutations.

Combined mutation pattern analyses of epidermal growth factor receptor and K-ras genes for the differential diagnosis of primary versus metastatic lung adenocarcinomas.

e21010 Background: The differential diagnosis of multiple primary lung cancers (MPLCs) from pulmonary metastases (PMs) is sometimes difficult based solely on the Martini and Melamed's criteria. We investigated whether combined mutation pattern analyses of the epidermal growth factor receptor (EGFR) and K-ras genes were useful for differentiating between MPLCs and PMs. Methods: We conducted a retrospective review of 84 tumors (81 adenocarcinomas and three atypical adenomatous hyperplasias) in 36 patients with multifocal lung adenocarcinomas. Genomic DNA was extracted from paraffin-embedded tissue. The peptide nucleic acid (PNA)-locked nucleic acid polymerase chain reaction clamp method was used for EGFR mutation analysis. The PNA-mediated PCR clamping method was used for K-ras mutation analysis. We determined clonality status of secondary tumors based on the mutation patterns of EGFR and K-ras by comparing them with primary tumors. Correlations between the mutation status and the proportion of bronchioloalveolar carcinoma (BAC) component in a tumor were examined. Results: EGFR and K-ras mutations were detected in 38 (45%) and 24 (29%) of 84 tumors, respectively. Thirty-four (71%) of secondary tumors were diagnosed as a different clonality (MPLC). Seven (15%) of secondary tumors were classified into the same clonality (PM). Clonality status could not be determined for the seven (15%) remaining secondary tumors. A clonality assessment based on the EGFR and K-ras mutation status was possible in 41 (84%) of 48 secondary tumors, and it was consistent with the Martini and Melamed's criteria in 29 (71%) of 41 secondary tumors. The proportion of BAC component in a tumor did not correlate with the EGFR/K-ras mutation status. Conclusions: The combined mutation pattern analyses of EGFR and K-ras enabled a definite distinction between PMLCs and PMs in a large portion of multifocal lung adenocarcinomas. Mutations of EGFR and K-ras in multifocal lung adenocarcinomas frequently occurred randomly, which support the concept of “field cancerization.” No significant financial relationships to disclose.

First-line gefitinib therapy for elder advanced non-small cell lung cancer patients with epidermal growth factor receptor mutations: Multicenter phase II trial (NEJ 003 study).

7561 Background: First line treatment by gefitinib for NSCLC patients with EGFR mutations has been validated by us (NEJ 002 Study) and WJTOG3405. In these studies, patients with ages less than 75 years were enrolled. Namely, there has been no data of the first-line gefitinib for elderly patients with EGFR mutations. The purpose of this study was to investigate the efficacy and the feasibility of gefitinib for chemotherapy-naive patients of 75 years or older advanced non-small cell lung cancer (NSCLC) harboring the epidermal growth factor receptor (EGFR) mutations. Methods: Chemotherapy-naive patients of 75 years of age or older with advanced NSCLC, Eastern Cooperative Oncology Group performance status 0-1, adequate organ function who had EGFR mutations examined by peptide nucleic acid-locked nucleic acid polymerase chain reaction clamp (PNA-LNA PCR Clamp) method were enrolled and receive 250 mg/day of gefitinib alone. Results: Between January 2008 and May 2009, 31 patients were enrolled, of whom all patie...

Abstract 1800: Analysis of EGFR mutations before and after EGFR-TKIs treatment

Abstract Background: Gefitinib is the epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) that has the dramatically effects in selective patients with non-small cell lung cancer (NSCLC). EGFR mutations predict response and survival in patients treated with gefitinib. However, almost of these patients have a relapse within a year after the start of therapy. Although the mechanisms of acquired resistance to Gefitinib were MET amplification, L861Q and hepatocyte growth factor(HGF), main reason was a secondary EGFR mutation, threonine to methionine at codon 790 in exon 20 (T790M). Therefore, we analyzed EGFR mutations after gefitinib treatment in addition to before treatment in patients with NSCLC. Materials and methods: From December 2004 to September 2009, 37 patients with advanced NSCLC harboring EGFR mutations were treated with gefitinib in our hospital. When tumor was relapsed, we got written informed consent from patients, and re-examination of EGFR mutations was performed in 9 patients by present. EGFR mutations were examined by mutant-enriched polymerase chain reaction (PCR) method and/or peptide nucleic acid-locked nucleic acid (PNA-LNA) PCR clamp method. Samples were the paraffin-embedded specimens, transbronchial biopsied tissues, surgically resected tissues, bronchial washing liquids, and pleural effusion, and we used relapsed tumor samples at secondary analysis. In addition, we evaluated the response to treatment according to the Response Evaluation Criteria in Solid Tumors (RECIST) and progression free survival defined as the time from the date of beginning treatment to the date of disease progression or death. Results: 37 patients treated by gefitinib, response rate was 60%(22/37) and disease control rate was 78%(29/37). Within a year, most patients were relapse. In 9 patients, we could analyze EGFR mutations again. Secondary analysis of EGFR mutations was performed in safety. T790M, a resistant mutation of EGFR, was detected in 4 patients. Samples from lymph node biopsy were used in 2 patients, pleural effusion was in a patient, and transbronchial biopsied tissue was in a patient. 1 patient was adenosquamous cell carcinoma, and all of the rest were adenocarcinoma. Despite emergence of T790M, in a patient, readministration of gefitinib was effective (stable disease), furthermore, treatment of erlotinib after gefitinib was also effective (partial response). In 1 patient, secondary analysis is performing at present. Conclusion: These results suggested the importance of EGFR analysis after relapse in patients treated with gefitinib. We must consider why erlotinib was effective in patients with T790M, and screen appropriate subjects of readministration of EGFR-TKIs. The new therapeutic strategy according to the mechanism of resistance to EGFR-TKI is expected. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1800.

A Phase II Trial of Erlotinib Monotherapy in Pretreated Patients with Advanced Non-small Cell Lung Cancer Who Do Not Possess Active EGFR Mutations: Okayama Lung Cancer Study Group Trial 0705

Efficacy of gefitinib therapy strongly depends on epidermal growth factor receptor (EGFR)-mutation status in Asian patients with non-small cell lung cancer. Recently, the survival advantage of erlotinib, another tyrosine kinase inhibitor, was not affected by EGFR mutation status in a phase III trial, indicating that patients with EGFR-wild-type (EGFR-wt) tumors might also benefit from this tyrosine kinase inhibitor. The aim of this trial was to evaluate the efficacy and toxicity of erlotinib in Japanese patients with EGFR-wt tumors. The primary end point was an objective response. Patients with EGFR-wt tumors previously receiving one to three chemotherapy regimens were enrolled in this trial. The mutation status was assessed using the peptide nucleic acid-locked nucleic acid polymerase chain reaction clamp method. Erlotinib was administered (150 mg/d) until disease progression or unacceptable toxicities occurred. Thirty patients were enrolled between January and December 2008. Objective response was observed in one patient (3.3%), and the disease became stable in 18 patients (60.0%). Skin rash was the most common side effect. Grades 3-4 adverse events included pulmonary embolism, keratitis, and anemia. Two other patients developed interstitial lung disease (grades 1 and 2). Nevertheless, all these events were reversible, resulting in no treatment-related deaths. With a median follow-up time of 10.7 months, the median survival time and median progression-free survival times were 9.2 and 2.1 months, respectively. This is the first prospective biomarker study showing that erlotinib therapy for pretreated patients with EGFR-wt tumors seems to have a modest activity with no irreversible toxicity.