New studies look beyond EGFR mutations for clues to sensitivity to erlotinib.
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BACKGROUND AND OBJECTIVES: In this paper we examined the influence of epidermal growth factor receptor (EGFR) gene mutations on EGFR expression, downstream mediators, and survival in patients with non-small cell lung cancer (NSCLC). METHODS: We retrospectively analyzed the tumors of 53 patients with completely resected pathological stage I-IIIA NSCLC for the presence of EGFR gene mutations, the expression of EGFR mRNA and protein, phosphoryl-Akt, and phosphoryl-mitogen-activated protein kinase (MAPK) using immunostaining, and patients' prognosis. RESULTS: EGFR mutations were associated with elevations in EGFR mRNA (P = 0.004) and protein (P = 0.029) expression, but not with the expression of phosphoryl-Akt or phosphoryl-MAPK. The 5-year survival rate for all patients who exhibited an EGFR mutation was similar to those who were free of such mutations (71% vs. 56%, P = 0.252). However, the 5-year survival rate of patients with either a stage I adenocarcinoma or large cell carcinoma who had an EGFR mutation was significantly greater than for those who did not have such a mutation (92% vs. 57%, P = 0.037). CONCLUSIONS: EGFR gene mutations were significantly associated with higher EGFR expression, but not with p-Akt or p-MAPK status. In early stage NSCLC, the presence of an EGFR gene mutation bode well for the patient's prognosis.
PURPOSE: EGFR mutations in lung cancer increase sensitivity to an EGFR tyrosine kinase inhibitor, gefitinib. Mutation analysis of EGFR is essential for prediction of gefitinib response and avoidance of the coincidental severe side effects for the unresponsive population. The purpose of the present study is to apply DHPLC as a screening system of detection of EGFR mutations for large scaled population. METHODS: EGFR mutations were detected by both DHPLC procedure and direct sequencing using lung cancer tissue samples obtained from 97 patients (81 surgical specimens and 16 pleural effusions of non-resectable lung cancer patients). RESULTS: DHPLC analysis detected EGFR mutations in 5 h as opposed to 18 h by direct sequencing for ten samples, and it costs eightfold more expensive by direct sequencing than DHPLC. In addition, DHPLC analysis was sixfold more sensitive than sequencing analysis for detection of the point mutation of exon 21, L858R. Using this system, EGFR mutations in exons 18, 19 and 21 were found in 34 of 97 patients (36%). Thirteen of the 15 patients with exon 21 mutations (87%) were female non-smokers, who were diagnosed with adenocarcinomas with the feature of BAC. Eight of the 18 patients with exon 19 mutations (44%) were 7 male and 1 female current or former smokers, and BAC feature was observed in 61% (8/18). CONCLUSION: DHPLC analysis for screening followed by sequencing analysis appears to be more sensitive and accurate, as well as easier and faster. In addition, these results suggest different mutagenesis and carcinogenesis pathways for mutations.
Somatic activating mutations in EGFR identify a subset of non-small cell lung cancer that respond to tyrosine kinase inhibitors. Acquisition of drug resistance is linked to a specific secondary somatic mutation, EGFR T790M. Here we describe a family with multiple cases of non-small cell lung cancer associated with germline transmission of this mutation. Four of six tumors analyzed showed a secondary somatic activating EGFR mutation, arising in cis with the germline EGFR mutation T790M. These observations implicate altered EGFR signaling in genetic susceptibility to lung cancer.
Activating mutations of EGFR are found frequently in a subgroup of patients with non-small cell lung cancer (NSCLC) and are highly correlated with the response to gefitinib and erlotinib. In the present study, we searched for mutations of EGFR, HER2 and KRAS in 264 resected primary NSCLC from Japanese patients and determined whether there is a correlation between genetic alterations of these genes and clinicopathological factors, together with 85 tumors that we reported previously. EGFR mutations were found in 102 of the total 349 tumors, and seven tumors had two missense mutations. Reverse transcription-polymerase chain reaction of EGFR and subsequent subcloning analyses identified that the double mutations occurred in the same allele. Furthermore, in 202 NSCLC analyzed by Southern blotting, we identified 11 tumors with gene amplification of EGFR, with eight tumors containing a mutation in EGFR. Sequence analysis detected only weak or no signals of the wild-type allele in the eight tumors, strongly suggesting that the mutated allele was amplified selectively. These findings indicate that a dual genetic change of EGFR can occur in the same allele either with a possible second-hit mutation or with amplification, which may imply a more selective growth advantage in a cancer cell. Meanwhile, HER2 mutations and amplifications were found in six of 349 tumors and three of 202 tumors, respectively, and KRAS mutations in 21 of 349 tumors. Mutations of the EGFR and HER2 genes were more frequently found in female never or light-smoking patients with adenocarcinoma, and there were no tumors that had two or more mutations simultaneously among EGFR, HER2 and KRAS. The current study further demonstrates that a double genetic event in EGFR can occasionally occur in lung cancer, thus providing new clues for understanding the involvement of epidermal growth factor receptor signaling cascades in the pathogenesis of NSCLC.
Activating EGFR somatic mutations have been shown to predict treatment response to small molecules targeting the EGFR intracellular tyrosine kinase domain. Recent work on cell-lines and animal models had demonstrated an inhibitory effect of EGFR tyrosine kinase inhibitors in hepatocellular and nasopharyngeal carcinoma, and clinical trials in these tumour types are ongoing. There are few data on the presence or prevalence of EGFR mutations in hepatocellular and nasopharyngeal carcinomas. We studied exons 18-21 of the EGFR gene from 100 hepatocellular and 102 nasopharyngeal carcinomas, and found no exonic mutations of potential significance. Alternative mechanisms may be important for the observed activity of small molecule EGFR tyrosine kinase inhibitors in hepatocellular and nasopharyngeal carcinomas.
A key event in patterning the developing Drosophila compound eye is the progressive restriction of the transcription factor Atonal in the morphogenetic furrow. The Atonal pattern evolves from expression in all cells to an over-dispersed pattern of single founder cells (the future R8 photoreceptors). This restriction involves Notch-mediated lateral inhibition. However, there have been inconsistent data on a similar proposed role for the Egf receptor (Egfr). Experiments using a conditional Egfr mutation (Egfr(tsla)) suggested that Egfr does not regulate Atonal restriction, whereas experiments using Egfr-null mosaic Minute+ clones suggested that it does. Here, we have re-examined both approaches. We report that the lesion in Egfr(tsla) is a serine to phenylalanine change in a conserved extracellular ligand-binding domain. We show by biochemical and genetic approaches that the Egfr(tsla) protein is rapidly and completely inactivated upon shift to the non-permissive temperature. We also find that on temperature shift the protein moves from the cell surface into the cell. Finally, we report a flaw in the Egfr-null mosaic Minute+ clone approach. Thus, we demonstrate that Egfr does not play a role in the initial specification or spacing of ommatidial founder cells.
BACKGROUND: The presence of epidermal growth factor receptor (EGFR) mutations in gefitinib-naive lung cancer patients has been reported to be higher in females, in non-smokers, in Japanese, and in adenocarcinoma patients, especially in bronchioloalveolar carcinoma (BAC). To further investigate the prevalence of EGFR mutations in relation to pathological factors, we evaluated EGFR mutations in series of Japanese adenocarcinoma patients who had never been treated with gefitinib. METHODS: In the previous studies, we examined mutation status in the tyrosine kinase domain of EGFR, exon18 through exon21, in 112 primary lung adenocarcinoma samples. Using these data, adenocarcinomas were histologically classified according to the presence or absence of bronchioloalveolar components. RESULTS: Among 112 patients, 48 had adenocarcinoma with BAC components. Those with adenocarcinomas with BAC components had higher frequency of EGFR mutation (28/48, 58%) than those with non-BAC adenocarcinoma (24/64, 37%, P = 0.036). Male patients had the same trend; 12/23 (52%) male patients with adenocarcinoma with BAC components and 10/47 (21%) of those with non-BAC adenocarcinoma had EGFR mutation (P = 0.0135) but there was no correlation between the EGFR mutation status and with/without BAC components in 42 female patients (P = 0.30). Among 11 male non-smokers, patients with adenocarcinoma with BAC components had a tendency to have EGFR mutation more frequently than those with non-BAC adenocarcinoma (P = 0.061). In clear contrast, the frequency of EGFR mutation did not differ significantly between male smoker patients with adenocarcinoma with BAC components and those with non-BAC. Among patients with adenocarcinoma with BAC components, those with adenocarcinoma with EGFR gene mutation had a significantly better 5 year survival than those with adenocarcinoma with wild-type (85.7 versus 46.0%, P = 0.0017). CONCLUSIONS: Adenocarcinomas with BAC components in male non-smokers seem to predict the presence of EGFR mutation. Half of female adenocarcinoma patients with EGFR mutation exhibit adenocarcinomas with non-BAC suggesting a different behavior from those in males. The prognosis of patients with adenocarcinoma with BAC components with EGFR gene mutation is predicted to be better than that of patients with adenocarcinoma with BAC components with wild-type EGFR gene.
EGFR and erbB-2 are targets for specific cancer therapy. The purpose of this study was to examine the frequency and clinicopathological correlations of gene amplification, protein expression, and mutations of EGFR and ERBB2 in serous carcinoma, the most common and aggressive type of ovarian cancer. Tissue microarray constructed of 398 carcinomas was examined by chromogenic in situ hybridization (CISH) and by immunohistochemistry. Cases with amplification of EGFR by CISH were further analyzed by fluorescence in situ hybridization. One hundred ninety-eight samples were analyzed for mutations in exons 18, 19, or 21 of EGFR and in exon 20 of ERBB2 using denaturating high-performance liquid chromatography and direct sequencing. Amplification of EGFR was present in 12% (41/333), low-level gain in 43% (144/333), and protein overexpression in 17% (66/379) of the tumors. Both increased copy number and overexpression of EGFR were associated with high tumor grade, greater patient age, large residual tumor size, high proliferation index, aberrant p53, and poor patient outcome. Furthermore, increased copy number of EGFR was associated with increased copy number of ERBB2. No mutations were identified in EGFR, whereas one tumor had an insertion mutation in exon 20 of ERBB2. Both amplification and protein overexpression of EGFR occur in serous ovarian carcinoma, but EGFR copy number has a stronger prognostic value. This makes EGFR amplification a potentially useful criterion for selecting patients in clinical trials testing the effect of EGFR inhibitors in serous ovarian carcinoma.
Recent reports that activating mutations of the EGFR have a significant association with the response to gefitinib drew much attention. Mutations are more frequently observed in Oriental patients, females, non-smokers and adenocarcinoma patients, which correspond to patient profiles predictive of a good clinical response with gefitinib. In vitro experiments also revealed EGFR mutant cell lines are highly sensitive to gefitinib. It seems that development of tailor-made therapy of lung cancer would be possible by the test for EGFR gene mutations. Furthermore, EGFR mutations are the first molecular change known to specifically occur in lung cancer, preferentially in never smokers, especially in adenocarcinoma that is increasing in incidence. It is ultimately necessary to identify non-tobacco-related carcinogens that cause EGFR mutations for effective prevention of lung cancer.
Cases of non-small-cell lung cancer (NSCLC) carrying the somatic mutation of epidermal growth factor receptor (EGFR) have been shown to be hyperresponsive to the EGFR tyrosine kinase inhibitor gefitinib (IRESSA). If EGFR mutations can be observed in serum DNA, this could serve as a noninvasive source of information on the genotype of the original tumor cells that could influence treatment and the ability to predict patient response to gefitinib. Serum genomic DNA was obtained from Japanese patients with NSCLC before first-line gefitinib monotherapy. Scorpion Amplified Refractory Mutation System technology was used to detect EGFR mutations. Wild-type EGFR was detected in all of the 27 serum samples. EGFR mutations were detected in 13 of 27 (48.1%) patients and two major EGFR mutations were identified (E746_A750del and L858R). The EGFR mutations were seen significantly more frequently in patients with a partial response than in patients with stable disease or progressive disease (P = 0.046, Fisher's exact test). The median progression-free survival was significantly longer in patients with EGFR mutations than in patients without EGFR mutations (200 versus 46 days; P = 0.005, log-rank test). The median survival was 611 days in patients with EGFR mutations and 232 days in patients without EGFR mutations (P > 0.05). In pairs of tumor and serum samples obtained from 11 patients, the EGFR mutation status in the tumors was consistent with those in the serum of 8 of 11 (72.7%) of the paired samples. Thus, EGFR mutations were detectable using Scorpion Amplified Refractory Mutation System technology in serum DNA from patients with NSCLC. These results suggest that patients with EGFR mutations seem to have better outcomes with gefitinib treatment, in terms of progression-free survival, overall survival, and response, than those patients without EGFR mutations.
We conducted a feasibility study to examine whether small numbers of cancer cells could be utilised for analysis of the EGFR gene status using the loop-hybrid mobility shift assay, which is a modified heteroduplex technique. Cytology specimens obtained by transbronchial abrasion were successfully used for analysis of the EGFR gene status in 50 of 52 (96.2%) patients diagnosed with class V non-small-cell carcinoma. Furthermore, the relationship between the EGFR gene status and clinical outcome was analysed in 25 patients treated with gefitinib. Overall, 10 of 11 patients with EGFR mutations in exon 19 or 21 showed tumour regression with gefitinib treatment, compared to only two of 14 patients with wild-type EGFR. The response rate was significantly higher in the EGFR mutation group than in the wild-type EGFR group (90.9 vs 14.3%, P=0.00014). Logistic regression analysis revealed that EGFR mutations in cytology specimens represented an independent predictor of the gefitinib response. The overall and progression-free survivals were significantly longer in the EGFR mutation group than in the wild-type EGFR group (P<0.05). In conclusion, cytology specimens could be useful for analysing the EGFR status in the majority of patients with non-small-cell lung cancer to determine whether they are likely to benefit from gefitinib treatment.
Recently, mutations in the epidermal growth factor receptor (EGFR) gene in nonsmall cell lung cancer (NSCLC) patients were reported to correlate with gefitinib response. Less than 30% of NSCLC patients are surgically resectable; however, molecular analysis has to rely on nonsurgical diagnostic tissue samples. The objective of this study is to investigate EGFR mutation analysis on needle biopsy/aspiration samples and its correlations with gefitinib response and patients' survival. EGFR mutation was assessed from DNA of 63 paraffin-embedded small needle biopsy/aspiration specimens from 62 patients with NSCLC treated with gefitinib. The peripheral blood lymphocyte DNA of the patients was sequenced to verify the EGFR mutation. EGFR mutations were found in 47% of 62 patients (60% of 20 CT-guided biopsies, 44% of 18 ultrasound-guided biopsies, 31% of 16 endoscopic biopsies and 44% of 9 effusion cell blocks). EGFR mutations were frequently present in females (p = 0.006) and never smokers (p = 0.04). Patients with EGFR mutations had a significantly better response rate compared to that of the nonmutation group (p < 0.001). Multivariate analysis showed that EGFR mutation (p < 0.001) and PS 0-1 (p = 0.02) were independently associated with a better response rate. Cox regression analysis showed that EGFR mutation was the independent prognostic factor for progression-free survival (p = 0.008) and overall survival (p = 0.03). In conclusion, EGFR mutation analysis is feasible in needle biopsy/aspiration paraffin-fixed specimens. EGFR mutation is an independent predictor of gefitinib response and survival in patients of advanced NSCLC treated by gefitinib.