No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Detection of epidermal growth factor receptor and human epidermal growth factor receptor 2 activating mutations in lung adenocarcinoma by high-resolution melting amplicon analysis: correlation with gene copy number, protein expression, and hormone receptor expression
Abstract
Activating mutations in the epidermal growth factor receptor (EGFR) (7p12.3-p12.1) and in the human epidermal growth factor receptor 2 (HER2) (17q21.1) characterize a subset of lung carcinomas. These mutations may relate to the response of the tumor to the tyrosine kinase inhibitors gefitinib and erlotinib. High-resolution melting amplicon analysis is a screening technique that has been shown to be able to detect missense mutations as well as deletions and insertions in tumor DNA isolated from paraffin-embedded tissue sections. In this study, we used high-resolution melting amplicon analysis to screen for EGFR and human HER2 activating mutations in 39 patients with primary lung adenocarcinoma. There were 20 cases that showed bronchioloalveolar histology and 19 cases that did not. The EGFR exons screened were exons 18, 19, 20, and 21, and the HER2 exons screened were exons 19 and 20. Six (15%) of the 39 patients had tumors that contained EGFR activating mutations. Four of the mutations were in adenocarcinomas, which had some bronchioloalveolar features, and 2 mutations were in tumors without bronchioloalveolar features. The EGFR mutations were in exon 19 (2 cases), exon 20 (2 cases), and exon 21 (1 case). One case contained mutations in both exons 18 and 20. One (2.6%) of the 39 patients had a tumor that contained an HER2 activating mutation, and the mutation was located in exon 20. Two of the 6 EGFR mutation-positive cases showed polysomy for chromosome 7, and each one showed overexpression of EGFR as determined by immunohistochemical staining. The other EGFR mutation-positive cases did not show EGFR overexpression and appeared disomic for chromosome 7. The HER2 mutation-positive case was in an adenocarcinoma with bronchioloalveolar features. This tumor did not show overexpression of HER2 and was disomic for chromosome 17. For the non-EGFR mutation-positive cases, 4 (13%) of 32 evaluated cases showed polysomy for chromosome 7 and EGFR. No case showed EGFR gene amplification. Polysomy for chromosome 7 was not related to EGFR overexpression as estimated by immunohistochemistry. Estrogen and progesterone receptor expression was not strong in any of the cases and did not correlate with the presence of EGFR or HER2 mutations.
... Reagents and primer design have been described previously. [17,[20][21][22] Primer sequences and expected amplicon sizes are shown in table 1. Polymerase chain reaction and high resolution melting curve analysis These procedures have been described. [17] Briefly, PCR was performed in a capillary cuvette (total volume 20 ul) on a Light Cycler (Roche Diagnostics, Indianapolis IN), with reactions using dUTP instead of dTTP. ...
... [17,[20][21][22] Primer sequences and expected amplicon sizes are shown in table 1. Polymerase chain reaction and high resolution melting curve analysis These procedures have been described. [17] Briefly, PCR was performed in a capillary cuvette (total volume 20 ul) on a Light Cycler (Roche Diagnostics, Indianapolis IN), with reactions using dUTP instead of dTTP. Prior to PCR the samples were incubated with 1 unit of uracil Nglycosylase (Amperase, Applied Biosystems, Foster City, CA) to prevent "carry-over" contamination. ...
... Sample cuvettes were then transferred individually to the HR-1, a high resolution DNA melting analysis instrument (Idaho Technology, Salt Lake City, UT) and melting analysis was performed as described. [17] Because melt profile may vary depending on DNA concentration, serial dilutions of genomic DNA were used as control standards. All patient samples were run in triplicate. ...
... G695X (G719X) X = (A, C, S, D) Mutations in Gly695 were reported in lung cancer [2] [5] [6] [7] ...
... The corresponding residue in ErbB2 (Gly766) also undergoes substitutions in cancer cells [16], suggesting that these mutations are indeed oncogenic. L834X (L858X) X = [R,M] L834R was reported in lung cancer [1] [2] [5] [6] [7] [15] [17]. L834M was reported in lung cancer [2]. ...
... ErbB2 Alterations In-frame Insertions/Duplications in Exon20 in ErbB2 G776insYV MA (Ser744 in the EGFR). Insertions following residue Gly776 were reported in cancer cells [5] [22] [23] [24] [25] ...
... Each of the previously described HRM mutation screening assays for EGFR have limitations preventing them from being practical for one or more of the following reasons: they do not cover all of exons 18 to 21 [29,40], they do not discriminate against common SNPs leading to unnecessary sequencing [28], they do not detect all mutations that are detectable by sequencing [29,40] and they have not been validated against a large panel of clinical samples with previously determined mutations [28]. ...
... In one assay, a primer is located over the c.2184+19 common SNP potentially resulting in non-amplification of the mutant allele [28]. Allele dropout due to sequence variation at the primer binding site has been previously demonstrated [41]. ...
... Each of the previously described HRM mutation screening assays for EGFR have limitations preventing them from being practical for one or more of the following reasons: they do not cover all of exons 18 to 21 [29,40], they do not discriminate against common SNPs leading to unnecessary sequencing [28], they do not detect all mutations that are detectable by sequencing [29,40] and they have not been validated against a large panel of clinical samples with previously determined mutations [28]. ...
Background
Epithelial growth factor receptor (EGFR) and KRAS mutation status have been reported as predictive markers of tumour response to EGFR inhibitors. High resolution melting (HRM) analysis is an attractive screening method for the detection of both known and unknown mutations as it is rapid to set up and inexpensive to operate. However, up to now it has not been fully validated for clinical samples when formalin-fixed paraffin-embedded (FFPE) sections are the only material available for analysis as is often the case.
Methods
We developed HRM assays, optimised for the analysis of FFPE tissues, to detect somatic mutations in EGFR exons 18 to 21. We performed HRM analysis for EGFR and KRAS on DNA isolated from a panel of 200 non-small cell lung cancer (NSCLC) samples derived from FFPE tissues.
Results
All 73 samples that harboured EGFR mutations previously identified by sequencing were correctly identified by HRM, giving 100% sensitivity with 90% specificity. Twenty five samples were positive by HRM for KRAS exon 2 mutations. Sequencing of these 25 samples confirmed the presence of codon 12 or 13 mutations. EGFR and KRAS mutations were mutually exclusive.
Conclusion
This is the first extensive validation of HRM on FFPE samples using the detection of EGFR exons 18 to 21 mutations and KRAS exon 2 mutations. Our results demonstrate the utility of HRM analysis for the detection of somatic EGFR and KRAS mutations in clinical samples and for screening of samples prior to sequencing. We estimate that by using HRM as a screening method, the number of sequencing reactions needed for EGFR and KRAS mutation detection can be reduced by up to 80% and thus result in substantial time and cost savings.
... [21]. However, some studies have reported a lack of relationship between EGFR overexpression and the actual presence of EGFR mutation [22,23], and it is, therefore, recommended to correlate these cases with molecular studies to select a target population for a better treatment response with EGFR inhibitors [22][23][24]. Gumuskaya et al. reported a positive association of membranous staining pattern of EGFR expression with EGFR gene amplification (increased gene copy number) compared to the cytoplasmic staining pattern and recommended to prioritize those patients for anti-EGFR treatment [25]. ...
... [21]. However, some studies have reported a lack of relationship between EGFR overexpression and the actual presence of EGFR mutation [22,23], and it is, therefore, recommended to correlate these cases with molecular studies to select a target population for a better treatment response with EGFR inhibitors [22][23][24]. Gumuskaya et al. reported a positive association of membranous staining pattern of EGFR expression with EGFR gene amplification (increased gene copy number) compared to the cytoplasmic staining pattern and recommended to prioritize those patients for anti-EGFR treatment [25]. ...
Introduction
Metaplastic breast carcinoma (MBC) is one of the rare special subtypes of breast carcinoma associated with poor prognostic features compared with invasive ductal carcinoma. Moreover, therapeutic options are limited in MBC owing to frequent triple-negative profiles of these tumors. Epidermal growth factor receptor (EGFR) is a proto-oncogene that is overexpressed in many human cancers, and is a potential therapeutic target. Therefore, in this study, we evaluated the expression of EGFR in MBC by immunohistochemistry, and its association with clinicopathological and prognostic parameters.
Methods
We conducted a retrospective observational study in the Department of Histopathology at Liaquat National Hospital and Medical College, Pakistan, over a period of seven years. A total of 61 cases with a histopathological diagnosis of MBC were included in the study. All slides were reviewed by histopathologists for diagnostic confirmation. Histopathological parameters, such as tumor size, grade, and nodal metastasis, were recorded. The representative tissue blocks were also retrieved and immunohistochemical studies were performed for cytokeratin 5/6 (CK5/6), Ki67, and EGFR.
Results
The mean age of the patients was 44.48 ± 13.01 years. The mean tumor size was 5.72 ± 2.72 cm, with most of the cases belonging to tumor (T)-stage T3. Axillary metastasis was present in 57.4% cases, and the perinodal extension was present in 11.5% cases. Most tumors were grade III (85.2%), with a mean Ki67 index of 39.67% ± 20.38%. Most of the cases were nonbasal (83.6%), owing to the absent CK5/6 expression. Tumor recurrence was noted in 14.8% cases, with a median follow-up of 43 (13-83) months and median disease-free survival of 36 (12-60) months. Positive EGFR expression was noted in 52.5% cases. A significant association of EGFR expression was noted with tumor grade, mean Ki67 index, axillary metastasis, and nodal (N)-stage. Cases with positive EGFR expression were found to have higher grade (grade III), with higher Ki67 index, higher frequency of axillary metastasis, and higher N-stage. Moreover, cases with positive EGFR expression had lower disease-free survival compared to cases with negative EGFR expression.
Conclusion
We found that a significant proportion of triple-negative MBC expressed EGFR. Moreover, EGFR overexpression was associated with poor pathological parameters and lower disease-free survival. Therefore, EGFR can be considered a potential prognostic biomarker and therapeutic target in triple-negative MBC; however, the correlation between gene amplification and protein overexpression is required to better uncover the role of EGFR as a therapeutic target.
... Some of these assays are more sensitive than direct sequencing and could therefore overcome the limitations stated above. However, they are not suitable for routine clinical use for various reasons such as cost, complexity, long turnaround time, low specificity or unavailability [5,[31][32][33][34]. In summary, they would be more appropriate in very demanding scenarios, such as with a relatively young patient, an aggressive tumour or few treatment options, where we need to use a very fast and reliable assay. ...
... The need for sensitive methods for the study of mutations in patients with lung carcinoma is especially relevant given that the percentage of cellularity of many of the samples presented for analysis, mainly small biopsies, can be a limiting factor after the use of classificatory IHC [49,50]. The pathologist must evaluate the sample available, not only to determine the tumour percentage but also to assess the presence of fibrosis or lymphocytic infiltrate as these can also affect the sensitivity of the determination and the decision about which methodology to use [5,22,32]. In our series, several cases were paradigmatic in this regard although the analysis of the influence of the histological parameters in the detection of EGFR mutations was not statistically significant (data not shown). ...
The objective of this study is to compare two EGFR testing methodologies (a commercial real-time PCR kit and a specific EGFR mutant immunohistochemistry), with direct sequencing and to investigate the limit of detection (LOD) of both PCR-based methods. We identified EGFR mutations in 21 (16%) of the 136 tumours analyzed by direct sequencing. Interestingly, the Therascreen EGFR Mutation Test kit was able to characterize as wild-type one tumour that could not be analyzed by direct sequencing of the PCR product. We then compared the LOD of the kit and that of direct sequencing using the available mutant tumours. The kit was able to detect the presence of a mutation in a 1% dilution of the total DNA in nine of the 18 tumours (50%), which tested positive with the real-time quantitative PCR method. In all cases, EGFR mutation was identified at a dilution of 5%. Where the mutant DNA represented 30% of the total DNA, sequencing was able to detect mutations in 12 out of 19 cases (63%). Additional experiments with genetically defined standards (EGFR ΔE746-A750/+ and EGFR L858R/+) yielded similar results. Immunohistochemistry (IHC) staining with exon 19-specific antibody was seen in eight out of nine cases with E746-A750del detected by direct sequencing. Neither of the two tumours with complex deletions were positive. Of the five L858R-mutated tumours detected by the PCR methods, only two were positive for the exon 21-specific antibody. The specificity was 100% for both antibodies. The LOD of the real-time PCR method was lower than that of direct sequencing. The mutation specific IHC produced excellent specificity.
... However, archived tumor samples are more commonly analyzed with some compromise in detection sensitivity. FFPE samples are reported most frequently [94,95,[98][99][100]105,[112][113][114][115][116][117][118][119][120][121]. Cytology slides are another common source of tumor cells when no other tissue source is available [95,96,116,117,122] and methanolfixed paraffin-embedded (MFPE) tissues have also been analyzed. ...
... Therefore, EGFR-activating mutations are commonly used to establish cancer subsets with different therapies. Two cancers where these subsets apply are squamous cell carcinoma of the head and neck, and lung carcinomas [119,120]. While these studies show promise for personalized therapeutics, the development of new drugs to treat a broader range of cancers will expand such applications. ...
Among nucleic acid analytical methods, high-resolution melting analysis is gaining more and more attention. High-resolution melting provides simple, homogeneous solutions for variant scanning and genotyping, addressing the needs of today's overburdened laboratories with rapid turnaround times and minimal cost. The flexibility of the technique has allowed it to be adopted by a wide range of disciplines for a variety of applications. In this review we examine the broad use of high-resolution melting analysis, including gene scanning, genotyping (including small amplicon, unlabeled probe and snapback primers), sequence matching and methylation analysis. Four major application arenas are examined to demonstrate the methods and approaches commonly used in particular fields. The appropriate usage of high-resolution melting analysis is discussed in the context of known constraints, such as sample quality and quantity, with a particular focus placed on proper experimental design in order to produce successful results.
... Other sample sources have included dried blood spots [36], buccal cells [33] and frozen tumour specimens [22,26,48]. Archived samples in the form of methanol-fixed tissue [28], formalinfixed paraffin-embedded tissue [24,26,28,34,38,40] and cytology slides [28,29,39] have also been analysed successfully, although, again, sensitivity may be reduced [26,28]. Although the amount of template has been quantified before PCR in most studies, there may be reasonable tolerance of variation in quantity provided that samples amplify well [24,33]. ...
... The presence of a high-frequency benign polymorphism within an amplicon can be challenging for HRM, as for other scanning techniques, because polymorphisms are detected as effectively as disease-causing mutations. Consequently, in the presence of a common polymorphism, the positive predictive value of a variant profile can be low [10] and the need to confirm the identity of variants means that excess sequencing has to be carried out [24,27,34,35,38,39]. Simple avoidance is not always possible, particularly for polymorphisms close to or within exons. ...
Mutation scanning techniques are used to detect sequence variants without the need for prior knowledge of the identity or precise location of the variant, in contrast with genotyping techniques, which determine the status of a specific variant. High-resolution melting is a recently developed method that shows great potential as a mutation scanning technique. Sensitivity and specificity for mutation detection are extremely high and the technique also has advantages of cost and throughput. Practical considerations for successful mutation scanning by high-resolution melting are also discussed in this review.
... Overexpression of HER2 has frequently been associated with various types of cancer including gastric, lung, and breast cancers [7][8][9][10][11][12]. Clinical studies demonstrated increased anticancer efficiency when EGFR and HER2 were simultaneously used, relative to targeting either protein using only one type of inhibitor [13,14]. ...
Experimental and theoretical studies have provided structural information regarding the shift from inactive to active EGFR, throughout which both conformations are linked via binding to specific tyrosine kinase inhibitors. For HER2, an intermediate active-inactive receptor conformation is present in the PDB, which has been co-crystallized with tak-285. The affinity of HER2 in monomeric state to tak-285 has been previously reported. However, the lack of structural knowledge of HER2 limits our capacity to understand whether tak-285, or other known HER2 inhibitors, are selectively active, inactive or intermediate forms of HER2. To elucidate mechanisms by which tak-285 binds to HER2, we first obtained information regarding the structural features of the active state of HER2 via microsecond MD simulations from the crystallized intermediate structure previously determined. Based on these HER2 conformers, together with the inactive HER2 conformer obtained in a previous study, we used docking and MD simulations coupled to MMGBSA approach to assess binding of tak-285 and lapatinib, known HER2/EGFR dual inhibitors, to HER2. Structural and energetic studies revealed that tak-285 binds with a greater affinity than lapatinib to active and intermediate active-inactive forms of HER2. This is in accordance with experimental findings that shown the tak-285 inhibitor has increased activity relative to lapatinib in breast cancer cell lines.
... To allow direct sequencing of HRM products, M13-tagged primers were designed. This approach has advantage over previously reported HRM assays for EGFR [5][6][7][8][9][10] that need separate PCR reactions for sequencing. The HRM conditions and subsequent unidirectional sequencing procedures were essentially as described before [3]. ...
Background : Increasing data from clinical trials support EGFR and K-ras mutation status as predictive markers of tumour response to EGFR-targeted therapies. Consequently, rapid and reliable mutation screening assays are demanded to guide rational use of EGFR-targeted therapies.
Methods : In this study, we describe the development of high resolution melting (HRM) technology-based assays with direct sequencing confirmation possibility for mutation screening of the EGFR gene (exons 19, 20 and 21) in routine diagnostic specimens, and compared assay findings to those of conventional nested-PCR following cycle-sequencing.
Results : In reconstruction experiments, each HRM assay following sequencing demonstrated a sensitivity of ≤5% of mutated DNA in a background of wild-type DNA. The panel of EGFR HRM assays following sequencing applied to a series of genomic DNA samples isolated from 68 FFPE NSCLC specimens correctly identified all EGFR mutations that were previously found by nested-PCR following cycle-sequencing. The HRM approach additionally scored two mutations not detected by the conventional assay.
Complementary HRM following sequencing for K-ras revealed three mutations. EGFR and K-ras mutations were mutually exclusive.
Conclusions : The panel of designed HRM assays with direct reflex sequencing possibility provides an effective method for mutation screening of EGFR and K-ras genes in routine diagnostic specimens, thereby allowing the selection of the treatment of choice in clinical practice.
... The balance of EGFR mutant patients in the combination and erlotinib arms were similar, 15 and 21%, respectively. Importantly, among the unplanned EGFR WT subgroup analysis, we note that prior investigations have reported on differences in steroid hormone receptor expression in EGFR mutant as compared to EGFR WT tumors in the clinic [23,[45][46][47][48]. Our findings show that steroid hormone receptor expression is greater in EGFR WT tumors versus EGFR mutant tumors among patients enrolled on this trial. ...
Objectives:
This open-label, randomized phase II trial evaluated antitumor efficacy of an antiestrogen, fulvestrant, in combination with human epidermal growth factor receptor (EGFR) inhibitor, erlotinib, in advanced non-small cell lung cancer (NSCLC) patients.
Materials and methods:
Patients with advanced or metastatic NSCLC, ECOG 0-2, previous chemotherapy unless patient refusal, and no prior EGFR-directed therapy were randomized 2:1 to erlotinib 150 mg oral daily plus 500 mg intramuscular fulvestrant on day 1, 15, 29 and every 28 days thereafter or erlotinib alone 150 mg oral daily. The primary end point was objective response rate (ORR); secondary endpoints included progression free survival (PFS) and overall survival (OS).
Results:
Among 106 randomized patients, 100 received at least one dose of study drug. ORR was 16.4% (11 of 67 patients) for the combination versus 12.1% (4 of 33 patients) for erlotinib (p = 0.77). PFS median 3.5 versus 1.9 months [HR = 0.86, 95% CI (0.52-1.43), p = 0.29] and OS median 9.5 versus 5.8 months [HR = 0.92, 95% CI (0.57-1.48), p = 0.74] numerically favored the combination. In an unplanned subset analysis, among EGFR wild type patients (n = 51), but not EGFR mutant patients (n = 17), median PFS was 3.5 versus 1.7 months [HR = 0.35, 95% CI (0.14-0.86), p = 0.02] and OS was 6.2 versus 5.2 months [HR = 0.72, 95% CI (0.35-1.48), p = 0.37] for combined therapy versus erlotinib, respectively. Notably, EGFR WT patients were more likely to be hormone receptor-positive (either estrogen receptor α- and/or progesterone receptor-positive) compared to EGFR mutant patients (50% versus 9.1%, respectively) (p = 0.03). Treatment was well tolerated with predominant grade 1-2 dermatologic and gastrointestinal adverse effects.
Conclusion:
Addition of fulvestrant to erlotinib was well tolerated, with increased activity noted among EGFR wild type patients compared to erlotinib alone, albeit in an unplanned subset analysis.
... The technique has already been employed to scan for somatic mutations in the KIT, BRAF, EGFR, ERBB2, TP53 and KRAS genes. [30][31][32][33][34][35] The causes of CHDs in the most cases are unknown, but the molecular evolution and gene analysis of heart have led to identification of some mutations associated with the CHDs. In our previous study in Kurdish patients with atrial and ventricular wall defects referred to Sanandaj and Kermanshah Hospitals, was detected no mutation in NKX2.5 gene and 3 mutations in TBX5 gene. ...
Background:
The mutations in GATA4 gene induce inherited atrial and ventricular septation defects, which is the most frequent forms of congenital heart defects (CHDs) constituting about half of all cases.
Method:
We have performed High resolution melting (HRM) mutation scanning of GATA4 coding exons of nonsyndrome 100 patients as a case group including 39 atrial septal defects (ASD), 57 ventricular septal defects (VSD) and four patients with both above defects and 50 healthy individuals as a control group. Our samples are categorized according to their HRM graph. The genome sequencing has been done for 15 control samples and 25 samples of patients whose HRM analysis were similar to healthy subjects for each exon. The PolyPhen-2 and MUpro have been used to determine the causative possibility and structural stability prediction of GATA4 sequence variation.
Results:
The HRM curve analysis exhibit that 21 patients and 3 normal samples have deviated curves for GATA4 coding exons. Sequencing analysis has revealed 12 nonsynonymous mutations while all of them resulted in stability structure of protein 10 of them are pathogenic and 2 of them are benign. Also we found two nucleotide deletions which one of them was novel and one new indel mutation resulting in frame shift mutation, and 4 synonymous variations or polymorphism in 6 of patients and 3 of normal individuals. Six or about 50% of these nonsynonymous mutations have not been previously reported.
Conclusion:
Our results show that there is a spectrum of GATA4 mutations resulting in septal defects.
... The major signaling cascades activated by the ErbB family include the Ras-Raf-MEK-MAPK and the PI3K-Akt pathways, both of which result in transcription of genes involved in cellular proliferation, differentiation, and migration 31 . Aberrant activation of the ErbB network is frequently associated with cellular transformation and clinical malignancies such as lung, gastric, and breast cancers 29,79,102,117,164,200 . Overexpression of HER2 results in constitutive, ligand-independent activation of kinase signaling and is found in 20-30% of human breast cancers, where it is correlated with an aggressive tumor phenotype 168,195 . ...
The biochemical processes occurring within a living cell span a spectrum of scales in space and time, ranging from the nano- to the macro-scale. We note that a single cellular process often operates on multiple spatial and temporal scales, and thus it becomes necessary to combine modeling techniques in multiscale approaches, in which different levels of theory are synergized to describe a system at a number of scales or resolutions. In this work we apply a multiscale modeling framework to investigate the molecular regulatory mechanisms governing the activation of the ErbB receptor tyrosine kinases, a family of kinases which are commonly over-expressed or mutated in human cancers, with a focus on the HER3 and HER4 kinases. Our multiscale model of HER3, a kinase which, until recently, has been considered kinase-dead, presents evidence of HER3 catalytic activity and demonstrates that even a weak HER3 signal can be amplified by other cellular signaling mechanisms to induce drug resistance to tyrosine kinase inhibitors in silico. Thus HER3, rather than the commonly-targeted EGFR and HER2 kinases, may represent a superior therapeutic target in specific ErbB-driven cancers. In the second major study, we construct a multiscale model of activity in the HER4 kinase, which has been shown to perform an anti-cancer role in certain tumor cells, by steering the cell toward a program of cellular differentiation and away from a program of uncontrolled proliferation. Our HER4 model, which applies a combined computational and experimental approach, elucidates the molecular mechanisms underlying this HER4-mediated ‘switch’ to the cellular differentiation program, with the ultimate aim of exploiting or modulating the HER4 pathway as a potential therapy in specific ErbB-driven cancers. Furthermore, the model provides structural insights into the effects of several HER4 somatic mutations which have recently been discovered in a subset of cancer patients, and which abrogate the anti-cancer effects of HER4 activity. We have illustrated that multiscale modeling provides a powerful and quantitative platform for investigating the complexity inherent in intracellular signaling pathways and rationalizing the effects of molecular perturbations on downstream signaling events and ultimately, on the cell phenotype.
... It is an in-tube method requiring the inclusion of a saturating intercalating dye in the PCR mix and the addition of a high resolution melt step after PCR. The technique has already been employed to scan for somatic mutations in the KIT, BRAF, EGFR, ERBB2, TP53 and KRAS genes [20][21][22][23][24]. The main purpose of this study determines the role of gene mutations in CHD and genotype-phenotype correlation in ASD and VSD them by HRM, that is a highly effective scanning technique. ...
Background
Congenital heart diseases (CHD) are the most common of all birth defects, affecting nearly 0.9% of all live births. Nkx2-5 mutations were reported to cause CHD but data in Kurdish populations of Iran are limited.
Objectives
In this experimental study, we performed high resolution melt (HRM) mutation scanning of Nkx2-5 exons of non-syndrome patients.
Patients and Methods
Thirty nine patients with atrial septal defect and 57 patients with ventricular septal defect, 4 patients possessing both defects as case groups and 50 healthy controls. Then we grouped samples according to HRM graph and sequenced several samples from each group.
Results
HRM analysis showed 2 deviated curves for exon 1 and one group for exon 2A and exon 2B. Then, 2 samples of exon 1 that showed different HRM curves, 3 samples of another group from this exon and 5 samples of exon 2A, 2B and healthy controls were randomly sequenced. The results of sequencing confirmed the HRM analysis, and one polymorphism (A65G) was identified in 2 atrial septal defects with deviated curves.
Conclusions
The environmental and effective factors on the heart development within embryonic evolution as well as the possibility of the existence of the mutation in coding genes of the other cardiac transcription factors such as GATA4 and TBX5 can be the reasons for the lack of the pathogenic mutation in this study. It is suggested in further related studies to investigate normal and abnormal cardiac tissue samples of these studied patients and coding genes of the other cardiac transcription factors.
... Obviously, patients with HER2 mutations will not be offered this therapeutic option because of the low activity of HER2 pathway in this population. Paradoxically, HER2 mutations are not considered to be the main driver of genetic alterations to override tumour aggressiveness, unlike in other malignancies, such as NSCLC and colorectal carcinomas [30][31][32][33][34]. HER2 somatic mutations have been shown recently to drive tumorigenesis in HER2-negative breast cancers [13]. ...
In women with metastatic breast cancer (MBC), introduction of the anti-HER2 (human epidermal growth factor receptor-2) directed therapies including trastuzumab, pertuzumab, lapatinib, and/or trastuzumab-DM1 has markedly improved overall survival. However, not all cases of HER2-positive breast tumours derive similar benefit from HER2-directed therapy, and a significant number of patients experience disease progression because of primary or acquired resistance to anti-HER2-directed therapies. We integrated genomic and clinicopathological analyses in a cohort of patients with refractory breast cancer to anti-HER2 therapies to identify the molecular basis for clinical heterogeneity. To study the molecular basis underlying refractory MBC, we obtained 36 MBC tumours tissues and used next-generation sequencing to investigate the mutational and transcriptional profiles of 83 genes. We focused on HER2 mutational sites and HER2 pathways to identify the roles of HER2 mutations and the HER2 pathway in the refractoriness to anti-HER2 therapies. Analysis using massively parallel sequencing platform, CancerSCAN™, revealed that HER2 mutations were found in six of 36 patients (16.7%). One patient was ER (estrogen receptor)-positive and HER2-negative and the other five HER2 mutated patients were HER2-positive and HR (hormone receptor)-negative. Most importantly, four of these five patients did not show any durable clinical response to HER2-directed therapies. The HER2 pathway score obtained through transcriptional analyses identified that Growth Receptor Biding protein 2 (GRB2) was the most significantly down regulated gene in the HER2 mutated samples. Detection of HER2 mutations using higher deep DNA sequencing may identify a predictive biomarker of resistance to HER2-directed therapy. Functional validation is warranted.
... The major signaling networks activated by the ErbB family include the Ras-Raf-MEK-MAPK and PI3K-Akt pathways, both of which result in transcription of genes involved in cellular proliferation, differentiation, and migration [5]. Aberrant activation of the ErbB network is correlated with oncogenesis and development of lung, gastric, and breast cancers [6][7][8][9][10][11][12]. In particular, mutation or overexpression of HER2 results in uncontrolled, ligand-independent activation of kinase signaling and is correlated with 20-30% of human breast cancers [13,14]. ...
Human epidermal growth factor receptor 2 (HER2)/ErbB2 is a receptor tyrosine kinase belonging to the EGFR/ErbB family and is overexpressed in 20-30% of human breast cancers. Since there is a growing effort to develop pharmacological inhibitors of the HER2 kinase for the treatment of breast cancer, it is clinically valuable to rationalize how specific mutations impact the molecular mechanism of receptor activation. Although several crystal structures of the ErbB kinases have been solved, the precise mechanism of HER2 activation remains unknown, and it has been suggested that HER2 is unique in its requirement for phosphorylation of Y877, a key tyrosine residue located in the activation loop (A-loop). In our studies, discussed here, we have investigated the mechanisms that are important in HER2 kinase domain regulation and compared them with the other ErbB family members, namely EGFR and ErbB4, to determine the molecular basis for HER2's unique mode of activation. We apply computational simulation techniques at the atomic level and at the electronic structure (quantum mechanical) level to elucidate details of the mechanisms governing the kinase domains of these ErbB members. Through analysis of our simulation results, we have discovered potential regulatory mechanisms common to EGFR, HER2, and ErbB4, including a tight coupling between the A-loop and catalytic loop that may contribute to alignment of residues required for catalysis in the active kinase. We further postulate an autoinhibitory mechanism whereby the inactive kinase is stabilized through sequestration of catalytic residues. In HER2, we also predict a role for phosphorylated Y877 in bridging a network of hydrogen bonds that fasten the A-loop in its active conformation, suggesting that HER2 may be unique among the ErbB members in requiring A-loop tyrosine phosphorylation for functionality. In EGFR, HER2, and ErbB4, we discuss the possible effects of activating mutations. Delineation of the activation mechanism of HER2 in the context of the other ErbB members is crucial for understanding how the activated kinase might interact with downstream molecules and couple to signaling cascades that promote cancer. Our comparative analysis furthers insight into the mechanics of activation of the HER2 kinase and enables us to predict the effect of an identified insertion mutation on HER2 activation. Further understanding of the mechanism of HER2 kinase activation at the atomic scale and how it couples to downstream signaling at the cellular scale will elucidate predictive molecular phenotypes that may indicate likelihood of response to specific therapies for HER2-mediated cancers.
... Dimerization results in auto-or trans-phosphorylation of tyrosine residues in the RTK C-terminal tail segments, which serve as docking sites for signaling molecules containing SH2 or PTB domains [7,8]. Aberrant activation of the ErbB network is frequently associated with cellular transformation and clinical malignancies such as lung, gastric, and breast cancers [9][10][11][12][13][14][15][16]. Overexpression of HER2 results in constitutive, ligand-independent activation of kinase signaling and is found in 20-30% of human breast cancers, where it is correlated with an aggressive tumor phenotype [17,18]. ...
In the ErbB/HER family of receptor tyrosine kinases, the deregulation of the EGFR/ErbB1/HER1, HER2/ErbB2, and HER3/ErbB3 kinases is associated with several cancers, while the HER4/ErbB4 kinase has been shown to play an anti-carcinogenic role in certain tumors. We present molecular and network models of HER4/ErbB4 activation and signaling in order to elucidate molecular mechanisms of activation and rationalize the effects of the clinically identified HER4 somatic mutants. Our molecular-scale simulations identify the important role played by the interactions within the juxtamembrane region during the activation process. Our results also support the hypothesis that the HER4 mutants may heterodimerize but not activate, resulting in blockage of the HER4-STAT5 differentiation pathway, in favor of the proliferative PI3K/AKT pathway. Translating our molecular simulation results into a cellular pathway model of wild type versus mutant HER4 signaling, we are able to recapitulate the major features of the PI3K/AKT and JAK/STAT activation downstream of HER4. Our model predicts that the signaling downstream of the wild type HER4 is enriched for the JAK-STAT pathway, whereas downstream of the mutant HER4 is enriched for the PI3K/AKT pathway. HER4 mutations may hence constitute a cellular shift from a program of differentiation to that of proliferation.
... 72 Careful dissection of cells from a suitably representative area selected by a pathologist is essential to ensure a successful test result. Other methods include PCR-single-strand conformational polymorphism analysis 73,74 and high resolution-melting amplicon analysis. 75,76 Relative to the direct sequencing method, the other two Figure 2 Frequency of mutations in exons 18-21 of the EGFR gene and the association with responsiveness to EGFR targeted therapy. ...
... High resolution melting [HRM] analysis is a novel method used in the identification of single nucleotide base variations. It is based on the principle that even a single nucleotide change influences the melting temperature of DNA when it melts from double stranded to single stranded DNA [64]. HRM uses third-generation fluorescent dyes [e.g. ...
Non-small cell lung cancer [NSCLC] is a major cause of cancer related deaths in the world. In a significant proportion of NSCLC cases, the Epidermal Growth Factor Receptor [EGFR] is over-expressed prompting the development of anti-EGFR therapies. Clinical studies of EGFR tyrosine kinase inhibitors [TKIs] demonstrated an overall response rate of 10% in NSCLC with higher response rates in females, never smokers, adenocarcinoma histology and East Asians. Mutations in exons 18-21 of the EGFR gene appear to be the most important molecular predictors of response to TKIs with response rates of >60% reported in most studies. Consequently screening NSCLC patients for tumours harbouring EGFR mutations will assist in selecting patients for TKI therapy. The gold standard for detecting EGFR mutations has been direct DNA sequencing however the sensitivity of this molecular technique is limited by the amount of tumour DNA is time and resource consuming. Recently several highly sensitive techniques have been developed to detect EGFR mutant DNA in different biological samples. In this review we aim to provide an overview of the clinical relevance of screening for EGFR mutations in NSCLC and recent molecular tests that have been developed for this purpose to allow the reader to critically evaluate the various methodologies that are available.
... Other studies have also shown that ARMS can be used to detect EGFR mutations in cytology samples from transbronchial needle aspirates [17] or pleural effusion [18] and that this technique appeared to be more sensitive than direct sequencing in this sample type. Other methods for EGFR mutation testing, including pyrosequencing [19] and highresolution melting analysis [20], also exist. ...
Background:
Epidermal growth factor receptor (EGFR) mutation is predictive for the efficacy of EGFR tyrosine kinase inhibitors in advanced non-small-cell lung cancer (NSCLC) treatment. We evaluated the performance, sensitivity, and concordance between five EGFR tests.
Materials and methods:
DNA admixtures (n = 34; 1%-50% mutant plasmid DNA) and samples from NSCLC patients [116 formalin-fixed paraffin-embedded (FFPE) tissue, 29 matched bronchofiberscopic brushing (BB) cytology, and 20 additional pleural effusion (PE) cytology samples] were analyzed. EGFR mutation tests were PCR-Invader, peptide nucleic acid-locked nucleic acid PCR clamp, direct sequencing, Cycleave, and Scorpion Amplification Refractory Mutation System (ARMS). Analysis success, mutation status, and concordance rates were assessed.
Results:
All tests except direct sequencing detected four mutation types at ≥1% mutant DNA. Analysis success rates were 91.4%-100% (FFPE) and 100% (BB and PE cytology), respectively. Inter-assay concordance rates of successfully analyzed samples were 94.3%-100% (FFPE; kappa coefficients: 0.88-1.00), 93.1%-100% (BB cytology; 0.86-1.00), and 85.0%-100% (PE cytology; 0.70-1.00), and 93.1%-96.6% (0.86-0.93) between BB cytology and matched FFPE.
Conclusions:
All EGFR assays carried out comparably in the analysis of FFPE and cytology samples. Cytology-derived DNA is a viable alternative to FFPE samples for analyzing EGFR mutations.
... It is an in-tube method that requires the inclusion of a saturating intercalating dye in the PCR mix and the addition of a high resolution melt step after PCR. This technology has already been used to scan for somatic mutations in the TP53, KIT, BRAF, EGFR, ERBB2, KRAS, MUTYH genes [15][16][17][18][19] and also X-linked genetic disorders [20][21][22]. ...
... 72 Careful dissection of cells from a suitably representative area selected by a pathologist is essential to ensure a successful test result. Other methods include PCR-single-strand conformational polymorphism analysis 73,74 and high resolution-melting amplicon analysis. 75,76 Relative to the direct sequencing method, the other two Figure 2 Frequency of mutations in exons 18-21 of the EGFR gene and the association with responsiveness to EGFR targeted therapy. ...
The majority of lung adenocarcinoma patients with epidermal growth factor receptor- (EGFR) mutated or EML4-ALK rearrangement-positive tumors are sensitive to tyrosine kinase inhibitors. Both primary and acquired resistance in a significant number of those patients to these therapies remains a major clinical problem. The specific molecular mechanisms associated with tyrosine kinase inhibitor resistance are not fully understood. Clinicopathological observations suggest that molecular alterations involving so-called 'driver mutations' could be used as markers that aid in the selection of patients most likely to benefit from targeted therapies. In this review, we summarize recent developments involving the specific molecular mechanisms and markers that have been associated with primary and acquired resistance to EGFR-targeted therapy in lung adenocarcinomas. Understanding these mechanisms may provide new treatment avenues and improve current treatment algorithms.
... These rates can vary due to the inclusion of cancers from different subsites within the head and neck, methods used to assess gene amplification and tumor scoring methods. In contrast to lung adenocarcinomas in which activating EGFR mutations result in ligand-independent signaling [39][40][41][42][43], such activating EGFR mutations are infrequent in HNSCC [44,45]. EGFR gene amplification resulting in upwards of 12 copies per cell has been reported in HNSCC patients compared to copy numbers detected in normal mucosa from noncancer patients [46]. ...
Molecular therapeutics for treating epidermal growth factor receptor-(EGFR-) expressing cancers are a specific method for treating cancers compared to general cell loss with standard cytotoxic therapeutics. However, the finding that resistance to such therapy is common in clinical trials now dampens the initial enthusiasm over this targeted treatment. Yet an improved molecular understanding of other receptor tyrosine kinases known to be active in cancer has revealed a rich network of cross-talk between receptor pathways with a key finding of common downstream signaling pathways. Such cross talk may represent a key mechanism for resistance to EGFR-directed therapy. Here we review the interplay between EGFR and Met and the type 1 insulin-like growth factor receptor (IGF-1R) tyrosine kinases, as well as their contribution to anti-EGFR therapeutic resistance in the context of squamous cell cancer of the head and neck, a tumor known to be primarily driven by EGFR-related oncogenic signals.
... They reported that some of the EGFR mutant patients with major clinical response to gefitinib or erlotinib showed negative EGFR immunostaining [45]. Other studies have also noted such disagreement between EGFR immunoexpression and presence of mutations detected via molecular diagnostic methods [37,46]. These results suggest the importance of molecular diagnostic methods to identify EGFR mutations and subsequently those who will benefit from EGFR inhibitor therapy. ...
Triple negative breast cancer is associated with poorer prognosis and unresponsiveness to endocrine and anti-HER2 directed agents. Despite emerging data supporting the use of polyADP-ribose polymerase (PARP) inhibitors, complete and durable responses are rare and exploration of additional targeted therapies is needed. Epidermal growth factor receptor (EGFR) is expressed in triple negative breast cancer and several clinical trials are testing the role of anti-EGFR directed therapy. However, the rate of EGFR mutations is poorly defined. We, therefore, sought to characterize EGFR mutations in triple negative breast cancers.
Seventy samples were randomly chosen from a cohort of 653 triple negative breast tumours for EGFR mutation analysis. These samples were immunostained for EGFR protein expression and consisted of negatively stained and positively stained cases. DNA was extracted from paraffin blocks and polymerase chain reaction was performed to amplify exon regions 18 to 21 of the EGFR gene. Direct sequencing of the purified PCR products was performed.
EGFR mutations were found in 8 of 70 samples (11.4%). Mutations were predominantly exon 19 deletions (4 of 70 samples, 5.7%), which clustered in the region spanning codons 746 to 759 within the kinase domain of EGFR. Two types of exon 19 deletions were seen: a 15 nucleotide deletion (del E746-A750) (2 of 70 samples) and a 24 nucleotide deletion (del S752 - I759) (2 of 70 samples). Other exon 19 mutations observed were the inversion of the complementary strand (1 of 70 samples). Exon 21 mutations included missense substitution, L858R (1 of 70 samples) and T847I (2 of 70 samples). Mutations observed were independent of EGFR protein expression determined by immunohistochemical staining.
This study is among the first to document the presence and estimate the prevalence of EGFR mutations in triple negative breast cancer. These findings have potential implications for the design of clinical trials involving anti-EGFR directed therapy which currently do not select for patients based on presence of activating EGFR mutations, which may hence be underpowered to detect significant benefit in unselected populations. More complete sampling of EGFR mutation status in triple negative breast cancer is needed to determine the true mutation rate.
... In addition, the HRM method can identify heterozygous single-base changes in PCR products with a sensitivity N95% and specificity N99% [18]. Thus, this single close-tube method has recently become popular for detection and scanning of mutations in many genes [11][12][13][19][20][21][22][23][24][25][26][27]. ...
The objective of this study is to develop and evaluate a high-resolution melting (HRM) method for detection of SLC4A1 mutations and polymorphisms.
The HRM method was optimized for detection of 18 known SLC4A1 variants. It was then used for analysis of 16 blind DNA samples highly enriched with two common mutations, Southeast Asian ovalocytosis (SAO) and band 3 Bangkok 1 (G701D), to compare the results with that of the conventional procedures.
The HRM method was able to detect all 18 SLC4A1 variants. In the samples in which homozygous wild-type and homozygous variant could not be distinguished by difference plots, they were spiked with a sample carrying known homozygous genotype, resulting in their clear differentiation. The HRM method had 100% efficiency for detection of mutations in the blind DNA samples, when compared with that of the conventional techniques.
The developed HRM method is efficient and reproducible for detection of SLC4A1 mutations and polymorphisms.
... We also looked at the possibility that the HR status of the tumor could correlate with the presence of EGFR mutations. A small study by Willmore-Payne et al. 27 previously found that ER/PR staining did not correlate with EGFR mutations, but their number of cases with EGFR mutation (n ϭ 6) was small. However, a recent Japanese study on surgically resected adenocarcinoma reported a high expression of ER␣ (49.4%) and ER (48.5%) among 447 patients, and the authors also found that strong nuclear expression of ER was independently associated with the EGFR mutations. ...
Epidermal growth factor receptor (EGFR) mutations are more common in lung adenocarcinoma and in female patients of East-Asian origin. We aimed to assess the expression of female hormone receptors in East-Asian lung adenocarcinomas, their correlation with EGFR mutations, and prognostic significance.
Estrogen receptor (ER)alpha, ERbeta, progesterone receptor (PR), and Her-2 expression were examined using immunohistochemical methods on 109 lung adenocarcinoma cases. EGFR mutations were analyzed by partially denaturing high performance liquid chromatography. Association of hormone receptor with clinical factors was assessed using the Fisher's exact test. Associations with survival were assessed using the Cox proportional hazard model.
Using scoring criteria routinely used for breast cancer, there were four (4%) ERalpha, one (1%) ERbeta, six (6%) PR, and one (1%) Her-2 positive cases. Considering any staining as positive, 14 (14%) ERalpha, 10 (9%) ERbeta, 12 (12%) PR, and 26 (24%) Her-2 cases were positive. Thirty-nine patients (39%) had EGFR mutations. ERalpha positivity was significantly associated with ERbeta and PR positivity. There were more EGFR mutations seen in tumors with ERbeta positivity (60%) compared with those with negative expression (37.9%), and there was a trend toward a poorer outcome for patients with tumor that were positive for ERbeta and Her-2.
We found that ERalpha, ERbeta, PR, and Her-2 expression in lung adenocarcinoma are present but limited. This suggests that hormonal influence may not be an important factor to account for the high prevalence of lung cancer among the East-Asian women.
... The somatic nature of the mutations was confirmed by sequencing the adjacent normal skin in all three cases in which mutations were found. EGFR was mutated in one of 40 (2.5%) SCCs, a frequency not dissimilar to that detected in head and neck SCCs (7.3%) (Willmore-Payne et al, 2006). The particular Y727H mutation we found in exon 18 of EGFR has been observed in SCC of the lung (Pallis et al, 2007). ...
FGFR, fibroblast growth factor receptor; KA, keratoacanthoma; OTR, organ transplant recipient; RTK, receptor tyrosine kinase; SCC, squamous cell carcinoma
... To allow direct sequencing of HRM products, M13-tagged primers were designed. This approach has advantage over previously reported HRM assays for EGFR [5][6][7][8][9][10] that need separate PCR reactions for sequencing. The HRM conditions and subsequent unidirectional sequencing procedures were essentially as described before [3]. ...
Increasing data from clinical trials support EGFR and K-ras mutation status as predictive markers of tumour response to EGFR-targeted therapies. Consequently, rapid and reliable mutation screening assays are demanded to guide rational use of EGFR-targeted therapies.
In this study, we describe the development of high resolution melting (HRM) technology-based assays with direct sequencing confirmation possibility for mutation screening of the EGFR gene (exons 19, 20 and 21) in routine diagnostic specimens, and compared assay findings to those of conventional nested-PCR following cycle-sequencing.
In reconstruction experiments, each HRM assay following sequencing demonstrated a sensitivity of < or =5% of mutated DNA in a background of wild-type DNA. The panel of EGFR HRM assays following sequencing applied to a series of genomic DNA samples isolated from 68 FFPE NSCLC specimens correctly identified all EGFR mutations that were previously found by nested-PCR following cycle-sequencing. The HRM approach additionally scored two mutations not detected by the conventional assay. Complementary HRM following sequencing for K-ras revealed three mutations. EGFR and K-ras mutations were mutually exclusive.
The panel of designed HRM assays with direct reflex sequencing possibility provides an effective method for mutation screening of EGFR and K-ras genes in routine diagnostic specimens, thereby allowing the selection of the treatment of choice in clinical practice.
... Owing to concern regarding the sensitivity of the direct-sequencing method, a variety of other methods have been investigated to detect low abundance mutations and increase the sensitivity of the mutation assay. These include high-resolution melting analysis (Nomoto et al., 2006;Willmore-Payne et al., 2006;Fukui et al., 2008), single-stranded conformational polymorphism and denaturing high-performance liquid chromatography analysis of PCR amplicons after digestion by CEL1 endonuclease (Ja¨nne et al., 2006). These methods allow the rapid mutation screening of large numbers of samples with increased sensitivity but still require direct sequencing to identify or confirm mutations. ...
Most patients with non-small-cell lung cancer (NSCLC) present with advanced disease. Current treatment paradigms are shifting from cytotoxic chemotherapies alone to single-agent and combination biological and targeted therapies. As patient responses to these therapies vary, predictive biomarkers will be an important facet of a patient's diagnostic workup in personalized medicine, as there is accumulating evidence that they may enable the prognostication and prediction of therapeutic response. Potential biomarkers for the selection of patients with NSCLC most likely to benefit from epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs), such as gefitinib and erlotinib, include mutations, gene copy number increase and single-nucleotide polymorphisms of the EGFR gene, EGFR protein expression and oncogenic mutation on the KRAS gene. Many techniques are available to assay for these biomarkers. In this review, we present the current weight of evidence for using these methods as biomarkers for anti-EGFR therapy in patients with NSCLC.
... The major signaling cascades activated by the ErbB family include the Ras-Raf-MEK-MAPK and PI3K-Akt pathways, both of which result in transcription of genes involved in cellular proliferation, differentiation, and migration (5). Aberrant activation of the ErbB network is frequently associated with cellular transformation and clinical malignancies such as lung, gastric, and breast cancers (6)(7)(8)(9)(10)(11)(12). Overexpression of HER2 results in constitutive, ligand-independent activation of kinase signaling and is found in 20-30% of human breast cancers, where it is correlated with an aggressive tumor phenotype (13,14). ...
HER2 (ErbB2/Neu) is a receptor tyrosine kinase belonging to the epidermal growth factor receptor (EGFR)/ErbB family and is overexpressed in 20-30% of human breast cancers. Although several crystal structures of ErbB kinases have been solved, the precise mechanism of HER2 activation remains unknown, and it has been suggested that HER2 is unique in its requirement for phosphorylation of Y877, a key tyrosine residue located in the activation loop. To elucidate mechanistic details of kinase domain regulation, we performed molecular dynamics simulations of a homology-modeled HER2 kinase structure in active and inactive conformations. Principal component analysis of the atomistic fluctuations reveals a tight coupling between the activation loop and catalytic loop that may contribute to alignment of residues required for catalysis in the active kinase. The free energy perturbation method is also employed to predict a role for phosphorylated Y877 in stabilizing the kinase conformations. Finally, simulation results are presented for a HER2/EGFR heterodimer and reveal that the dimeric interface induces a rearrangement of the alphaC helix toward the active conformation. Elucidation of the molecular regulatory mechanisms in HER2 will help establish structure-function relationships in the wild-type kinase, as well as predict mutations with a propensity for constitutive activation in HER2-mediated cancers.
Background and objective:
Tumor growth, development, progression, metastasis, invasion and resistivity against drugs, solely depends on the recruitment of surrounding cells, extra cellular matrix and tumor microenvironment (TME). TME is directly as well as indirectly associated with cancer associated fibroblasts (CAF). The interactions of CAF with tumor surrounding cells, their origination, activation, transformation and ability to recruit other non-tumor cells for the clemency of tumor, are very complex and under active research since long. This study provides an in-depth review about CAF and highlights its potential targets for the regulation of TME as well as discuss about current drugs in clinical trials, targeting through CAF.
Conclusion:
The potential role of CAF in anti-tumor therapy is based on its coherent response against drugs, targeting different tumor sections through these genetically more stable and anti-immuno-supportive CAF cells. CAF can be targeted through immunity system; growth factors (GF) including Transforming growth factor (TGF), vascular endothelial GF, fibroblast GF, platelet derived GF; and TME elements including hypoxia, carbonic anhydrase, extracellular matrix (ECM). Collectively these features of CAF make it most vulnerable against single as well as combinational, anti-tumor therapy for synergistic or additive effects. Potential activities of CAF, their origination mechanisms and identification of meticulous bio-markers are needed to be investigated further. The rousing facts about them mutually culminate the anticipation of progress towards novel therapeutic establishment against cancer through CAFs that are under progressive research at all levels including, pre-clinical and clinical trials as well as possess much potential to be explored further.
Human epidermal growth factor receptor 2 (HER2)/ErbB2 is a receptor tyrosine kinase belonging to the EGFR/ErbB family and is overexpressed in 20-30% of human breast cancers. Since there is a growing effort to develop pharmacological inhibitors of the HER2 kinase for the treatment of breast cancer, it is clinically valuable to rationalize how specific mutations impact the molecular mechanism of receptor activation. Although several crystal structures of the ErbB kinases have been solved, the precise mechanism of HER2 activation remains unknown, and it has been suggested that HER2 is unique in its requirement for phosphorylation of Y877, a key tyrosine residue located in the activation loop (A-loop). In our studies, discussed here, we have investigated the mechanisms that are important in HER2 kinase domain regulation and compared them with the other ErbB family members, namely EGFR and ErbB4, to determine the molecular basis for HER2's unique mode of activation. We apply computational simulation techniques at the atomic level and at the electronic structure (quantum mechanical) level to elucidate details of the mechanisms governing the kinase domains of these ErbB members. Through analysis of our simulation results, we have discovered potential regulatory mechanisms common to EGFR, HER2, and ErbB4, including a tight coupling between the A-loop and catalytic loop that may contribute to alignment of residues required for catalysis in the active kinase. We further postulate an autoinhibitory mechanism whereby the inactive kinase is stabilized through sequestration of catalytic residues. In HER2, we also predict a role for phosphorylated Y877 in bridging a network of hydrogen bonds that fasten the A-loop in its active conformation, suggesting that HER2 may be unique among the ErbB members in requiring A-loop tyrosine phosphorylation for functionality. In EGFR, HER2, and ErbB4, we discuss the possible effects of activating mutations. Delineation of the activation mechanism of HER2 in the context of the other ErbB members is crucial for understanding how the activated kinase might interact with downstream molecules and couple to signaling cascades that promote cancer. Our comparative analysis furthers insight into the mechanics of activation of the HER2 kinase and enables us to predict the effect of an identified insertion mutation on HER2 activation. Further understanding of the mechanism of HER2 kinase activation at the atomic scale and how it couples to downstream signaling at the cellular scale will elucidate predictive molecular phenotypes that may indicate likelihood of response to specific therapies for HER2-mediated cancers.
Background: Companion diagnostics have become somewhat commonplace in the diagnostic workup of cancer patients after the identification of several predictive and prognostic markers. Although there are both IVD and CE marked kits available for their analysis, the majority of diagnostic centers use 'in-house' or 'home-grown' procedures. There are only a limited number of best evidence concordance studies that have assessed the diagnostic accuracy of any (IVD, CE, home-grown) of the tests in routine patient populations. Recognized quality assurance schemes are available to assist in harmonizing practices and offering best evidence recommendations for testing. However, for the somatic mutational analysis of EGFR additional factors complicate decisional trees that may only include classical mutational analysis (i.e. those limited to Δ19 and L858R). Patients & Methods: Since there are confounding issues related to decisional tree approaches for EGFR mutational testing, we have systematically reviewed the literature to assess various fields that may impinge upon best evidence approaches to offering technical recommendations for testing. We searched the PubMed and MEDLINE databases for articles (from inception through to 31 st August 2011; last search 17/09/2011) and journals known to publish information relevant to our topic. We imposed no language restrictions. Search terms included: "non-smallcell lung cancer"; "lung cancer", "epidermal growth factor receptor", "EGFR", "erlotinib", "tarceva", "gefitinib", "iressa", "mutation", "amplification". We also relied upon the somatic mutations-EGFR database (www.somaticmutations-EGFR.net) for assistance in re-publication bias exclusion. Results: A total of 85 concordance studies were identified using sequencing as the current "gold standard", investigating improved sensitivity of at least 13 distinct mutational screening techniques. Cumulative data indicates that the utility of either additional screening techniques (HRMA, d-HPLC), mutation enhancement pre-screening (ME-PCR) or alternative allele specific techniques (ARMS, PNA/LNA) for mutational hot-spots leads to an increase in the incidence of EGFR mutations in unselected patients by approximately 17%. Due to the broad spectrum of EGFR mutations, limiting screening to "classical" mutations would result in 25% of all mutations being missed. Non-nucleic acid-based mutation detection methods (for example by IHC), are currently limited by false positive results, heterogeneous concordance, and remain limited to investigational studies. Conclusions: Due to the broad spectrum of EGFR mutations and our limited understanding of the clinical significance of mutations outside the "classical" (Δ19, L858R), there is merit in continuing to assess the complete mutational spectrum. Studies using sequencing alone, though identifying known and new mutations, are not as sensitive as several alternative methodologies. Laboratories using a combination of broad range low sensitivity analysis (sequencing) coupled with high sensitivity "classical" mutational analysis may offer higher rates of true positive somatic EGFR mutational detection. Since there is approximately 25% of mutations lying outside the "classical" and another 17% identifiable simply by using higher sensitivity techniques, the true incidence of EGFR mutations may be underestimated. Laboratories should strive to incorporate best clinical and laboratory practices in supporting each diagnostic test with appropriately sensitive analytical procedures matching best evidence.
Objective To establish evidence-based recommendations for the molecular analysis of lung cancers that are that are required to guide EGFR - and ALK -directed therapies, addressing which patients and samples should be tested, and when and how testing should be performed. Participants Three cochairs without conflicts of interest were selected, one from each of the 3 sponsoring professional societies: College of American Pathologists, International Association for the Study of Lung Cancer, and Association for Molecular Pathology. Writing and advisory panels were constituted from additional experts from these societies. Evidence Three unbiased literature searches of electronic databases were performed to capture articles published published from January 2004 through February 2012, yielding 1533 articles whose abstracts were screened to identify 521 pertinent articles that were then reviewed in detail for their relevance to the recommendations. Evidence was formally graded for each recommendation. Consensus Process Initial recommendations were formulated by the cochairs and panel members at a public meeting. Each guideline section was assigned to at least 2 panelists. Drafts were circulated to the writing panel (version 1), advisory panel (version 2), and the public (version 3) before submission (version 4). Conclusions The 37 guideline items address 14 subjects, including 15 recommendations (evidence grade A/B). The major recommendations are to use testing for EGFR mutations and ALK fusions to guide patient selection for therapy with an epidermal growth factor receptor (EGFR) or anaplastic lymphoma kinase (ALK) inhibitor, respectively, in all patients with advanced-stage adenocarcinoma, regardless of sex, race, smoking history, or other clinical risk factors, and to prioritize EGFR and ALK testing over other molecular predictive tests. As scientific discoveries and clinical practice outpace the completion of randomized clinical trials, evidence-based guidelines developed by expert practitioners are vital for communicating emerging clinical standards. Already, new treatments targeting genetic alterations in other, less common driver oncogenes are being evaluated in lung cancer, and testing for these may be addressed in future versions of these guidelines.
We applied a simplified method using polymerase chain reaction (PCR)-based enzymatic digestion for the detection of epidermal growth factor receptor (EGFR) mutation.
Objective
To establish evidence-based recommendations for the molecular analysis of lung cancers that are that are required to guide EGFR- and ALK-directed therapies, addressing which patients and samples should be tested, and when and how testing should be performed.
Participants
Three cochairs without conflicts of interest were selected, one from each of the 3 sponsoring professional societies: College of American Pathologists, International Association for the Study of Lung Cancer, and Association for Molecular Pathology. Writing and advisory panels were constituted from additional experts from these societies.
Evidence
Three unbiased literature searches of electronic databases were performed to capture articles published published from January 2004 through February 2012, yielding 1533 articles whose abstracts were screened to identify 521 pertinent articles that were then reviewed in detail for their relevance to the recommendations. Evidence was formally graded for each recommendation.
Consensus Process
Initial recommendations were formulated by the cochairs and panel members at a public meeting. Each guideline section was assigned to at least 2 panelists. Drafts were circulated to the writing panel (version 1), advisory panel (version 2), and the public (version 3) before submission (version 4).
Conclusions
The 37 guideline items address 14 subjects, including 15 recommendations (evidence grade A/B). The major recommendations are to use testing for EGFR mutations and ALK fusions to guide patient selection for therapy with an epidermal growth factor receptor (EGFR) or anaplastic lymphoma kinase (ALK) inhibitor, respectively, in all patients with advanced-stage adenocarcinoma, regardless of sex, race, smoking history, or other clinical risk factors, and to prioritize EGFR and ALK testing over other molecular predictive tests. As scientific discoveries and clinical practice outpace the completion of randomized clinical trials, evidence-based guidelines developed by expert practitioners are vital for communicating emerging clinical standards. Already, new treatments targeting genetic alterations in other, less common driver oncogenes are being evaluated in lung cancer, and testing for these may be addressed in future versions of these guidelines.
As understanding of the molecular pathways that drive malignancy in human cancer improves, personalized genotype-based therapy in combination with the predictive biomarker for the efficacy of targeted therapy is becoming more popular in cancer management. Sanger sequencing, that has been the gold standard for mutation analysis in cancer since the 1970s, suffers from low sensitivity, complexity, and time-consuming and labor-intensive procedure. Although several PCR based molecular testing methods are being emerged, there is no universal assay available for genotyping of cancer biomarkers. Here we present a rapid, simple and sensitive assay for the detection of epidermal growth factor receptor (EGFR) mutation in non-small cell lung cancers (NSCLCs). The assay employs a novel double mis-matched primer (DMP) set to improve the detection ability of isothermal solid-phase amplification/detection (ISAD) based on silicon microring biosensor. We show that the EGFR-DMP can detect EGFR gene mutations within 20 min in a label-free and real-time manner. The EGFR-DMP was able to detect a mutation in a sample containing only 1% of the mutant cells in a mixture of wild-type cells. Furthermore, to validate the proposed assay for potential applications in clinical diagnostics, we examined paraffin-embedded tissue samples from 10 NSCLC patients for the presence of EGFR mutations by performing EGFR-DMP and direct sequencing. The EGFR-DMP assay was able to rapidly detect the mutation, with high sensitivity and specificity. The EGFR-DMP assay offers a robust and sensitive approach for the rapid identification of the EGFR mutation. The high sensitivity and specificity and rapidity of this approach may make it useful for predicting the clinical response to targeted EGFR TKIs as a companion diagnostic.
Background:
Dysregulation of HER2 signaling pathways results in tumor progression in several types of carcinomas. The aim of the current study is to identify clinicopathological characteristics of HER2-mutated non-small cell lung carcinomas (NSCLCs) in conjunction with HER2 protein expression, gene amplification, and phosphorylation.
Patients and methods:
We investigated 1275 patients including 1055 adenocarcinomas (ADCs), 146 squamous cell carcinomas, 2 large cell carcinomas, 8 sarcomatoid carcinomas, and 64 adenosquamous carcinomas. High-resolution melting analysis of HER2 hot spot inflame deletion mutations, chromogenic in situ hybridization for HER2 amplification, and immunostaining of wild-type and phosphorylated HER2 was performed.
Results:
HER2 mutations were detected in 46 (3.6%) of the NSCLCs, with mutations only present in the ADC. When analyzing ADC cases alone, the incidence of HER2 mutation was increased to 4.3%. All HER2-mutated tumors were negative for other driver gene alterations. HER2 mutation status correlated with never-smoker status and patients with smaller tumor size. HER2 amplifications were also identified in approximately half of the tumors with HER2 mutations. The overall survival rate was not significantly different between patients without and with HER2 mutations. When analyzing only invasive ADCs, HER2 mutation status was an independent factor for an unfavorable outcome. Amongst the 46 patients harboring HER2 mutations, univariate and multivariate analysis revealed that HER2 amplification was an unfavorable prognostic factor, while HER2 phosphorylation was a favorable prognostic factor.
Conclusions:
HER2 mutations were observed in 3.6% of NSCLCs, particularly in younger patients, those with no history of smoking, and those with small tumors. Amongst the patients with HER2 mutations, HER2 amplification and phosphorylation were independent prognostic factors.
One of the most important polymorphism in p53 gene occurs in codon 73 of exon 4. Individuals who have Arg/Arg allele may have an increase risk for progress of cancer. The present study was aimed to develop a rapid, inexpensive and simple high resolution melting curve analysis method to distinguish different genotype of codon 72 p53. This study was performed on 167 patients with four common cancers in Kurdistan. High resolution melt analysis of PCR products revealed different allele of codon 72 p53 gene. Genotyping by high resolution melt analysis was verified by DNA sequencing. The samples were categorized as Arg/Arg (31%), Arg/Pro (44%) and Pro/Pro (25%) in four cancer types. Patients with colorectal cancer had the highest frequency of Arg/Arg polymorphism (65%). High resolution melting analysis was completely compatible with sequencing results. The results indicate individuals with Arg/Arg allele of codon 72 p53 gene have an increased risk for development of cancer in Kurd ethnicity. In addition high resolution melting analysis is useful for rapid differentiation of p53 alleles and can be used for diagnostic purposes directly from clinical samples, as well as epidemiological studies.
Melting is non-destructive, allowing subsequent analysis of the PCR product when necessary. The simplicity and speed of high-resolution melting analysis are reflected by its increasing use in molecular diagnostics. The method is enabled by high-resolution melting instruments and dsDNA dyes that detect heteroduplexes. This chapter focuses on the high-resolution melting technique for genotyping, variant scanning, and sequence matching. Traditional genotyping by melting analysis relies on the use of labeled probes. Only those variants that are under the probe are detected. Conventional variant scanning identifies variants anywhere within a polymerase chain reaction (PCR) product, but requires separation of the mixture through a gel or other matrix. Both genotyping and scanning are performed with only a dsDNA dye and two primers. For fine discrimination of multiple variants within a particular region, an unlabeled probe or snapback primer tail can be included. High-resolution melting can rapidly establish sequence identity when specific genotyping is not required. Examples include HLA analysis for transplantation compatibility, repeat typing for identity matching, and genetic mapping. Dyes that detect heteroduplexes are critical for scanning and genotyping applications. Scanning and small amplicon melting methods depend strongly on instrument resolution, while genotyping with unlabeled probes or snapback primers can be performed adequately on standard instrumentation. These methods are fast, affordable, and simple.
Objective:
To establish evidence-based recommendations for the molecular analysis of lung cancers that are that are required to guide EGFR- and ALK-directed therapies, addressing which patients and samples should be tested, and when and how testing should be performed.
Participants:
Three cochairs without conflicts of interest were selected, one from each of the 3 sponsoring professional societies: College of American Pathologists, International Association for the Study of Lung Cancer, and Association for Molecular Pathology. Writing and advisory panels were constituted from additional experts from these societies.
Evidence:
Three unbiased literature searches of electronic databases were performed to capture articles published published from January 2004 through February 2012, yielding 1533 articles whose abstracts were screened to identify 521 pertinent articles that were then reviewed in detail for their relevance to the recommendations. Evidence was formally graded for each recommendation.
Consensus process:
Initial recommendations were formulated by the cochairs and panel members at a public meeting. Each guideline section was assigned to at least 2 panelists. Drafts were circulated to the writing panel (version 1), advisory panel (version 2), and the public (version 3) before submission (version 4).
Conclusions:
The 37 guideline items address 14 subjects, including 15 recommendations (evidence grade A/B). The major recommendations are to use testing for EGFR mutations and ALK fusions to guide patient selection for therapy with an epidermal growth factor receptor (EGFR) or anaplastic lymphoma kinase (ALK) inhibitor, respectively, in all patients with advanced-stage adenocarcinoma, regardless of sex, race, smoking history, or other clinical risk factors, and to prioritize EGFR and ALK testing over other molecular predictive tests. As scientific discoveries and clinical practice outpace the completion of randomized clinical trials, evidence-based guidelines developed by expert practitioners are vital for communicating emerging clinical standards. Already, new treatments targeting genetic alterations in other, less common driver oncogenes are being evaluated in lung cancer, and testing for these may be addressed in future versions of these guidelines.
Drawing on forty-one interviews with both documented and undocumented Latino restaurant workers in San Jose, California, and Houston, Texas, this article examines how documentation status shapes the legal consciousness of immigrant workers. I identify three common narratives that undocumented workers provide to justify not making claims on workplace protection. First, I highlight that an ever-present fear of deportation inhibits any formal confrontation. Second, I demonstrate how undocumented status leaves undocumented immigrants with a particularly pragmatic and short-term understanding of their working life in the United States, rendering their working conditions temporary and endurable to them. Third, I expand Gordon and Lenhardt's (2008) discussion of the centrality of work to the American conception of citizenship. I reiterate that this particular sense of belonging is situated vis-à-vis other low-wage workers. These findings provide sociolegal scholars important theoretical contributions for crafting a research agenda on the role of undocumented status and legal mobilization.
Background:
This pooled analysis evaluated the outcomes of prophylactic cranial irradiation (PCI) in 739 small-cell lung cancer (SCLC patients with stable disease (SD) or better following chemotherapy ± thoracic radiation therapy (TRT) to examine the potential advantage of PCI in a wider spectrum of patients than generally participate in PCI trials.
Patients and methods:
Three hundred eighteen patients with extensive SCLC (ESCLC) and 421 patients with limited SCLC (LSCLC) participated in four phase II or III trials. Four hundred fifty-nine patients received PCI (30 Gy/15 or 25 Gy/10) and 280 did not. Survival and adverse events (AEs) were compared.
Results:
PCI patients survived significantly longer than non-PCI patients {hazard ratio [HR] = 0.61 [95% confidence interval (CI): 0.52-0.72]; P < 0.0001}. The 1- and 3-year survival rates were 56% and 18% for PCI patients versus 32% and 5% for non-PCI patients. PCI was still significant after adjusting for age, performance status, gender, stage, complete response, and number of metastatic sites (HR = 0.82, P = 0.04). PCI patients had significantly more grade 3+ AEs (64%) compared with non-PCI patients (50%) (P = 0.0004). AEs associated with PCI included alopecia and lethargy. Dose fractionation could be compared only for LSCLC patients and 25 Gy/10 was associated with significantly better survival compared with 30 Gy/15 (HR = 0.67, P = 0.018).
Conclusions:
PCI was associated with a significant survival benefit for both ESCLC and LSCLC patients who had SD or a better response to chemotherapy ± TRT. Dose fractionation appears important. PCI was associated with an increase in overall and specific grade 3+ AE rates.
Clinical response to EGFR inhibitors has varied considerably from patient to patient. In this chapter, the molecular, pathological
and clinical correlates of therapeutic response and survival outcome are examined.
KeywordsEpidermal Growth Factor Receptor–Tyrosine Kinase Inhibitors–Molecular Diagnostics–Mutations–Fluorescence In Situ Hybridization–Immunohistochemistry–Lung Cancer
Approximately 25% of human breast cancers overexpress the HER2 (ErbB2) proto-oncogene, which confers a more aggressive tumor phenotype and associates with a poor prognosis in patients with this disease. Two approved therapies targeting HER2, the monoclonal antibody trastuzumab and the tyrosine kinase inhibitor lapatinib, are clinically active against this type of breast cancer. However, a significant fraction of patients with HER2+ breast cancer treated with these agents eventually relapse or develop progressive disease. This suggests that tumors acquire or possess intrinsic mechanisms of resistance that allow escape from HER2 inhibition. This review focuses on mechanisms of intrinsic and/or acquired resistance to HER2-targeted therapies that have been identified in preclinical and clinical studies. These mechanisms involve alterations to HER2 itself, coexpression or acquisition of bypass signaling through other receptor or intracellular signaling pathways, defects in mechanisms of cell cycle regulation or apoptosis, and host factors that may modulate drug response. Emerging clinical evidence already suggests that combinations of therapies targeting HER2 as well as these resistance pathways will be effective in overcoming or preventing resistance.
Fluorescence in situ hybridization (FISH) is a molecular cytogenetic assay that is commonly used in laboratory medicine. Most FISH assays are not approved by the US Food and Drug Administration but instead are laboratory-developed tests that use analyte-specific reagents. Although several guidelines exist for validation of FISH assays, few specific examples of FISH test validations are available in the literature.
To provide an example of how a FISH assay, using an analyte-specific reagent probe, may be validated in a clinical laboratory.
We describe the approach used by an individual laboratory for validation of a FISH assay for mixed lineage leukemia (MLL) gene.
Specific validation data are provided illustrating how initial assay performance characteristics in a FISH assay for MLL may be established.
Protocols for initial validation of FISH assays may vary between laboratories. However, all laboratories must establish several defined performance specifications prior to implementation of FISH assays for clinical use. We describe an approach used for assessing performance specifications and validation of an analyte-specific reagent FISH assay using probes for MLL rearrangement in interphase nuclei.
High Resolution Melting Analysis (HRMA) is becoming the preferred method for mutation detection. However, its accuracy in the individual clinical diagnostic setting is variable. To assess the diagnostic accuracy of HRMA for human mutations in comparison to DNA sequencing in different routine clinical settings, we have conducted a meta-analysis of published reports.
Out of 195 publications obtained from the initial search criteria, thirty-four studies assessing the accuracy of HRMA were included in the meta-analysis. We found that HRMA was a highly sensitive test for detecting disease-associated mutations in humans. Overall, the summary sensitivity was 97.5% (95% confidence interval (CI): 96.8-98.5; I(2) = 27.0%). Subgroup analysis showed even higher sensitivity for non-HR-1 instruments (sensitivity 98.7% (95%CI: 97.7-99.3; I(2) = 0.0%)) and an eligible sample size subgroup (sensitivity 99.3% (95%CI: 98.1-99.8; I(2) = 0.0%)). HRMA specificity showed considerable heterogeneity between studies. Sensitivity of the techniques was influenced by sample size and instrument type but by not sample source or dye type.
These findings show that HRMA is a highly sensitive, simple and low-cost test to detect human disease-associated mutations, especially for samples with mutations of low incidence. The burden on DNA sequencing could be significantly reduced by the implementation of HRMA, but it should be recognized that its sensitivity varies according to the number of samples with/without mutations, and positive results require DNA sequencing for confirmation.
The presence of EGFR mutations is correlated with a positive therapeutic response to tyrosine kinase inhibitors; therefore, the accurate detection of EGFR mutations is crucial when deciding appropriate therapeutic strategies. Recently, the rapid and sensitive assay smart amplification process version 2 (SmartAmp2) was developed. However, this method can only detect one type of mutation in EGFR exon 19; therefore, we applied the PNA technology to the SmartAmp2 assay to develop PNA-clamp SmartAmp2 for the detection of many types of deletions in EGFR exon 19, in a single reaction. This new assay was evaluated using 172 clinical samples. Thirty-nine (22.7%) samples were found to have deletions by PNA-clamp SmartAmp2; whereas 30 (17.4%) and 38 (22.1%) tumors were found to have deletions by direct sequencing and PNA-enriched sequencing, respectively. Three cases, in which we detected mutations with PNA-clamp SmartAmp2, but not with direct sequencing, were treated with gefitinib, and all cases showed a partial therapeutic response. Using clinical samples, we demonstrated that PNA-clamp SmartAmp2 can detect various types of mutations in EGFR exon 19 in a relatively short time and with high sensitivity. This method detected small amounts of mutant DNA and identified patients for whom clinical information was previously unavailable from other tests. This test may contribute to the administration of efficient therapeutic strategies.
Two classes of anti-EGF receptor (EGFR) agents, monoclonal anti-EGFR antibodies and small-molecule EGFR tyrosine kinase inhibitors, have been used for the treatment of non-small-cell lung cancer (NSCLC). However, only a subset of patients will benefit from EGFR-targeted therapy. The discovery of biomarkers that select the appropriate patients for the therapy and predict the responses to the therapy is urgently needed. Molecular genetic analyses provide new insights into EGFR pathway alterations and demonstrate promise for predicting the clinical outcome of patients with NSCLC. In this article, we summarize the latest available knowledge on the clinical impact of EGFR mutations, gene copy number, EGFR overexpression, phosphorylation expression and the alteration of the EGFR pathway downstream factors in predicting the response to EGFR-targeted therapy in NSCLC patients. The role of KRAS and BRAF mutations and ALK rearrangement in lung cancer-targeted therapy, are also reviewed.
Epidermal growth factor receptor (EGFR) is a transmembrane protein with cytoplasmic kinase activity that transduces important growth factor signaling from the extracellular milieu to the cell. Given that more than 60% of non-small cell lung carcinomas (NSCLCs) express EGFR, EGFR has become an important therapeutic target for the treatment of these tumors. Inhibitors that target the kinase domain of EGFR have been developed and are clinically active. More importantly, such tyrosine kinase inhibitors (TKIs) are especially effective in patients whose tumors harbor activating mutations in the tyrosine kinase domain of the EGFR gene. More recent trials have suggested that for advanced NSCLC patients with EGFR mutant tumors, initial therapy with a TKI instead of chemotherapy may be the best choice of treatment. Therefore, mutation testing is mandatory to identify these patients, given that selection based only on clinico-pathologic characteristics is inadequate. We review the role of EGFR mutations in the diagnosis and management of NSCLC.
EGFR and KRAS are the target genes for tumour response to epidermal growth factor receptor (EGFR) inhibitors.
To investigate EGFR and KRAS mutational status with high resolution melting (HRM) analysis applied to cytological material obtained from trans-thoracic needle aspiration (TTNA) in order to better select patients for targeted therapy.
DNA was extracted from fixed material of 108 TTNAs under CT guidance, from 108 consecutive patients. In 77 TTNAs (71.3.%) that were positive for non-small cell lung cancer, the variant in exon 21 (the missense mutation at codon 858, L858R) and the deletion in exon 19 (in frame deletion at codons 747-749) of the EGFR gene, and the point mutation in exon 2 of KRAS were investigated with HRM assay using sequencing as the reference "gold standard".
Nine (11.7%) samples were positive for KRAS exon 2 mutations, and two (2.6%) samples were positive for the EGFR exon 21 missense mutation by HRM assay. No deletion at exon 19 for EGFR was detected by HRM analysis. All HRM results were confirmed by direct DNA sequencing.
HRM analysis of cytological material was accurate for the detection of two major EGFR mutations and KRAS mutations in exon 2. HRM analysis was fast, easy to apply, cheap, highly reproducible, and could be used with small amounts of material, such as is obtainable with needle lavage. Therefore, it may be useful as an adjunct to the cytological report that yields valuable molecular information.
Constitutive activation of KIT receptor tyrosine kinase is critical in the pathogenesis of gastrointestinal stromal tumors. Imatinib mesylate, a selective tyrosine kinase inhibitor, has been shown in preclinical models and preliminary clinical studies to have activity against such tumors.
We conducted an open-label, randomized, multicenter trial to evaluate the activity of imatinib in patients with advanced gastrointestinal stromal tumor. We assessed antitumor response and the safety and tolerability of the drug. Pharmacokinetics were assessed in a subgroup of patients.
A total of 147 patients were randomly assigned to receive 400 mg or 600 mg of imatinib daily. Overall, 79 patients (53.7 percent) had a partial response, 41 patients (27.9 percent) had stable disease, and for technical reasons, response could not be evaluated in 7 patients (4.8 percent). No patient had a complete response to the treatment. The median duration of response had not been reached after a median follow-up of 24 weeks after the onset of response. Early resistance to imatinib was noted in 20 patients (13.6 percent). Therapy was well tolerated, although mild-to-moderate edema, diarrhea, and fatigue were common. Gastrointestinal or intraabdominal hemorrhage occurred in approximately 5 percent of patients. There were no significant differences in toxic effects or response between the two doses. Imatinib was well absorbed, with pharmacokinetics similar to those reported in patients with chronic myeloid leukemia.
Imatinib induced a sustained objective response in more than half of patients with an advanced unresectable or metastatic gastrointestinal stromal tumor. Inhibition of the KIT signal-transduction pathway is a promising treatment for advanced gastrointestinal stromal tumors, which resist conventional chemotherapy.
The epidermal growth factor receptor (EGFR) is frequently overexpressed in non-small-cell lung carcinoma (NSCLC), and EGFR inhibitors are promising new therapeutic agents. The molecular mechanisms responsible for EGFR overexpression are poorly understood. Materials and
Gene copy number and protein status of EGFR were investigated in microarrayed tumors from 183 NSCLC patients, including squamous cell carcinoma (SCC; 89 patients) and non-SCC (94 patients) histologies. Protein expression was assessed by immunohistochemistry on a scale from 0 to 400 (percentage of positive cells x staining intensity). Gene and chromosome 7 copy numbers were identified by fluorescent in situ hybridization (FISH).
EGFR protein overexpression was observed in 62% of the NSCLC (25% scored 201 to 300; 37% scored 301 to 400), more frequently in SCC than non-SCC (82% v 44%; P <.001), and in 80% of the bronchioloalveolar carcinomas. The prevalent FISH patterns were balanced disomy (40%) and trisomy (38%) for EGFR gene and chromosome 7 (40%), whereas balanced polysomy was seen in 13% and gene amplification was seen in 9% of the patients. Gene copy number correlated with protein expression (r = 0.4; P <.001). EGFR overexpression or high gene copy numbers had no significant influence on prognosis.
EGFR overexpression is frequent in NSCLC, is most prominent in SCC, and correlates with increased gene copy number per cell. High gene copy numbers per cell showed a trend toward poor prognosis. It will be important to evaluate EGFR gene and EGFR protein status and signal protein expression to properly interpret future clinical trials using EGFR inhibitors.
Receptor tyrosine kinase genes were sequenced in non–small cell lung cancer (NSCLC) and matched normal tissue. Somatic mutations
of the epidermal growth factor receptor gene EGFR were found in 15of 58 unselected tumors from Japan and 1 of 61 from the United States. Treatment with the EGFR kinase inhibitor
gefitinib (Iressa) causes tumor regression in some patients with NSCLC, more frequently in Japan. EGFR mutations were found in additional lung cancer samples from U.S. patients who responded to gefitinib therapy and in a lung
adenocarcinoma cell line that was hypersensitive to growth inhibition by gefitinib, but not in gefitinib-insensitive tumors
or cell lines. These results suggest that EGFR mutations may predict sensitivity to gefitinib.
Gefitinib ('Iressa', ZD1839) is an orally active epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor that has demonstrated antitumour activity and favourable tolerability in Phase II studies. We investigated whether EGFR expression levels could predict for response to gefitinib in patients with advanced non-small-cell lung cancer (NSCLC), who received gefitinib (250 mg day(-1)) as part of a worldwide compassionate-use programme. Tissue samples were analysed by immunohistochemistry to assess membrane EGFR immunoreactivity. Of 147 patients enrolled in our institution, 50 patients were evaluable for assessment of both clinical response and EGFR expression. The objective tumour response rate was 10% and disease control was achieved in 50% of patients. Although high EGFR expression was more common in squamous-cell carcinomas than adenocarcinomas, all objective responses were observed in patients with adenocarcinoma. Response and disease control with gefitinib were not associated with high EGFR expression. Overall, median survival was 4 months, and the 1-year survival rate was 18%. Strong EGFR staining correlated with shorter survival time for all patients. Gefitinib demonstrated promising clinical activity in this group of patients with NSCLC. These results have also shown that EGFR expression is not a significant predictive factor for response to gefitinib.
High-resolution amplicon melting analysis was used to scan for c-kit-activating mutations in exons 9, 11, 13, and 17 in 29 neoplasms diagnosed as gastrointestinal stromal tumors (GISTs). Immunohistochemically, 7 of 29 did not show strong CD 17 positivity and might represent true smooth muscle tumors or c-kit-negative GISTs. No c-kit-activating mutations were detected in the 7 CD117- cases by high-resolution amplicon melting analysis or direct DNA sequencing. Alterations in the remaining 22 CD117+ cases included 13 (59%) in exon 11, 2 (9%) in exon 9, 1 (5%) in exon 13, and none in exon 17. The genetic alterations consisted of point mutations and in-frame insertions, duplications, and deletions. In exon 11, 7 (54%) of 13 alterations have not been described previously. In 2 cases, the identical exon 11 mutation was observed in the primary tumor and a metastatic/recurrent lesion. In all cases, direct DNA sequencing confirmed that polymerase chain reaction products with an abnormal melting curve contained a mutation and products with a normal melting curve, a normal DNA sequence. High-resolution melting analysis can be used to scan DNA for potential c-kit-activating mutations and can aid in the diagnosis of GISTs.
Somatic mutations in the tyrosine kinase (TK) domain of the epidermal growth factor receptor (EGFR) gene are reportedly associated with sensitivity of lung cancers to gefitinib (Iressa), kinase inhibitor. In-frame deletions occur in exon 19, whereas point mutations occur frequently in codon 858 (exon 21). We found from sequencing the EGFR TK domain that 7 of 10 gefitinib-sensitive tumors had similar types of alterations; no mutations were found in eight gefitinib-refractory tumors (P = 0.004). Five of seven tumors sensitive to erlotinib (Tarceva), a related kinase inhibitor for which the clinically relevant target is undocumented, had analogous somatic mutations, as opposed to none of 10 erlotinib-refractory tumors (P = 0.003). Because most mutation-positive tumors were adenocarcinomas from patients who smoked <100 cigarettes in a lifetime ("never smokers"), we screened EGFR exons 2-28 in 15 adenocarcinomas resected from untreated never smokers. Seven tumors had TK domain mutations, in contrast to 4 of 81 non-small cell lung cancers resected from untreated former or current smokers (P = 0.0001). Immunoblotting of lysates from cells transiently transfected with various EGFR constructs demonstrated that, compared to wild-type protein, an exon 19 deletion mutant induced diminished levels of phosphotyrosine, whereas the phosphorylation at tyrosine 1092 of an exon 21 point mutant was inhibited at 10-fold lower concentrations of drug. Collectively, these data show that adenocarcinomas from never smokers comprise a distinct subset of lung cancers, frequently containing mutations within the TK domain of EGFR that are associated with gefitinib and erlotinib sensitivity.
Mutations in the tyrosine kinase (TK) domain of the epidermal growth factor receptor (EGFR) gene in lung cancers are associated with increased sensitivity of these cancers to drugs that inhibit EGFR kinase activity. However, the role of such mutations in the pathogenesis of lung cancers is unclear.
We sequenced exons 18-21 of the EGFR TK domain from genomic DNA isolated from 617 non-small-cell lung cancers (NSCLCs) and 524 normal lung tissue samples from the same patients and 36 neuroendocrine lung tumors collected from patients in Japan, Taiwan, the United States, and Australia and from 243 other epithelial cancers. Mutation status was compared with clinicopathologic features and with the presence of mutations in KRAS, a gene in the EGFR signaling pathway that is also frequently mutated in lung cancers. All statistical tests were two sided.
We detected a total of 134 EGFR TK domain mutations in 130 (21%) of the 617 NSCLCs but not in any of the other carcinomas, nor in nonmalignant lung tissue from the same patients. In NSCLC patients, EGFR TK domain mutations were statistically significantly more frequent in never smokers than ever smokers (51% versus 10%), in adenocarcinomas versus cancer of other histologies (40% versus 3%), in patients of East Asian ethnicity versus other ethnicities (30% versus 8%), and in females versus males (42% versus 14%; all P < .001). EGFR TK domain mutation status was not associated with patient age at diagnosis, clinical stage, the presence of bronchioloalveolar histologic features, or overall survival. The EGFR TK domain mutations we detected were of three common types: in-frame deletions in exon 19, single missense mutations in exon 21, and in-frame duplications/insertions in exon 20. Rare missense mutations were also detected in exons 18, 20, and 21. KRAS gene mutations were present in 50 (8%) of the 617 NSCLCs but not in any tumors with an EGFR TK domain mutation.
Mutations in either the EGFR TK domain or the KRAS gene can lead to lung cancer pathogenesis. EGFR TK domain mutations are the first molecular change known to occur specifically in never smokers.
Mutations in the epidermal growth factor receptor gene (EGFR) in lung cancers predict for sensitivity to EGFR kinase inhibitors. HER2 (also known as NEU, EGFR2, or ERBB2) is a member of the EGFR family of receptor tyrosine kinases and plays important roles in the pathogenesis of certain human cancers, and mutations have recently been reported in lung cancers. We sequenced the tyrosine kinase domain of HER2 in 671 primary non-small cell lung cancers (NSCLC), 80 NSCLC cell lines, and 55 SCLCs and other neuroendocrine lung tumors as well as 85 other epithelial cancers (breast, bladder, prostate, and colorectal cancers) and compared the mutational status with clinicopathologic features and the presence of EGFR or KRAS mutations. HER2 mutations were present in 1.6% (11 of 671) of NSCLC and were absent in other types of cancers. Only one adenocarcinoma cell line (NCI-H1781) had a mutation. All HER2 mutations were in-frame insertions in exon 20 and target the identical corresponding region as did EGFR insertions. HER2 mutations were significantly more frequent in never smokers (3.2%, 8 of 248; P=0.02) and adenocarcinoma histology (2.8%, 11 of 394; P=0.003). In 394 adenocarcinoma cases, HER2 mutations preferentially targeted Oriental ethnicity (3.9%) compared with other ethnicities (0.7%), female gender (3.6%) compared with male gender (1.9%) and never smokers (4.1%) compared with smokers (1.4%). Mutations in EGFR, HER2, and KRAS genes were never present together in individual tumors and cell lines. The remarkable similarities of mutations in EGFR and HER2 genes involving tumor type and subtype, mutation type, gene location, and specific patient subpopulations targeted are unprecedented and suggest similar etiologic factors. EGFR, HER2, and KRAS mutations are mutually exclusive, suggesting different pathways to lung cancer in smokers and never smokers.
Gefitinib is a selective inhibitor of the epidermal growth factor (EGFR) tyrosine kinase, which is overexpressed in many cancers, including non-small-cell lung cancer (NSCLC). We carried out a clinical study to compare the relationship between EGFR gene copy number, EGFR protein expression, EGFR mutations, and Akt activation status as predictive markers for gefitinib therapy in advanced NSCLC.
Tumors from 102 NSCLC patients treated daily with 250 mg of gefitinib were evaluated for EGFR status by fluorescence in situ hybridization (FISH), DNA sequencing, and immunohistochemistry and for Akt activation status (phospho-Akt [P-Akt]) by immunohistochemistry. Time to progression, overall survival, and 95% confidence intervals (CIs) were calculated and evaluated by the Kaplan-Meier method; groups were compared using the log-rank test. Risk factors associated with survival were evaluated using Cox proportional hazards regression modeling and multivariable analysis. All statistical tests were two-sided.
Amplification or high polysomy of the EGFR gene (seen in 33 of 102 patients) and high protein expression (seen in 58 of 98 patients) were statistically significantly associated with better response (36% versus 3%, mean difference = 34%, 95% CI = 16.6 to 50.3; P<.001), disease control rate (67% versus 26%, mean difference = 40.6%, 95% CI = 21.5 to 59.7; P<.001), time to progression (9.0 versus 2.5 months, mean difference = 6.5 months, 95% CI = 2.8 to 10.3; P<.001), and survival (18.7 versus 7.0 months, mean difference = 11.7 months, 95% CI = 2.1 to 21.4; P = .03). EGFR mutations (seen in 15 of 89 patients) were also statistically significantly related to response and time to progression, but the association with survival was not statistically significant, and 40% of the patients with mutation had progressive disease. In multivariable analysis, only high EGFR gene copy number remained statistically significantly associated with better survival (hazard ratio = 0.44, 95% CI = 0.23 to 0.82). Independent of EGFR assessment method, EGFR+/P-Akt+ patients had a statistically significantly better outcome than EGFR-, P-Akt-, or EGFR+/P-Akt- patients.
High EGFR gene copy number identified by FISH may be an effective molecular predictor for gefitinib efficacy in advanced NSCLC.
A clinical trial that compared erlotinib with a placebo for non-small-cell lung cancer demonstrated a survival benefit for erlotinib. We used tumor-biopsy samples from participants in this trial to investigate whether responsiveness to erlotinib and its impact on survival were associated with expression by the tumor of epidermal growth factor receptor (EGFR) and EGFR gene amplification and mutations.
EGFR expression was evaluated immunohistochemically in non-small-cell lung cancer specimens from 325 of 731 patients in the trial; 197 samples were analyzed for EGFR mutations; and 221 samples were analyzed for the number of EGFR genes.
In univariate analyses, survival was longer in the erlotinib group than in the placebo group when EGFR was expressed (hazard ratio for death, 0.68; P=0.02) or there was a high number of copies of EGFR (hazard ratio, 0.44; P=0.008). In multivariate analyses, adenocarcinoma (P=0.01), never having smoked (P<0.001), and expression of EGFR (P=0.03) were associated with an objective response. In multivariate analysis, survival after treatment with erlotinib was not influenced by the status of EGFR expression, the number of EGFR copies, or EGFR mutation.
Among patients with non-small-cell lung cancer who receive erlotinib, the presence of an EGFR mutation may increase responsiveness to the agent, but it is not indicative of a survival benefit.
Purpose To review recent advances in pathology and computed tomography (CT) of lung adenocarcinoma and bronchioloalveolar carcinoma (BAC). Methods A pathology/CT review panel of pathologists and radiologists met during a November 2004 International Association for the Study of Lung Cancer/American Society of Clinical Oncology consensus workshop in New York. The purpose was to determine if existing data was sufficient to propose modification of criteria for adenocarcinoma and BAC as newly published in the 2004 WHO Classification of Lung Tumors, and to address the pathologic/radiologic concept of diffuse/multicentric BAC. Results Solitary small, peripheral BACs have an excellent prognosis. Most lung adenocarcinomas with a BAC pattern are not pure BAC, but rather adenocarcinoma, mixed subtype with invasive patterns. This applies to tumors presenting with a diffuse/multinodular as well as solitary nodule pattern. The percent of BAC versus invasive components in lung adenocarcinomas appears to be prognostically important. However, a consensus definition of "minimally invasive" BAC with a favorable prognosis could not be achieved. While recognition of a BAC component is possible, the diagnosis of BAC with exclusion of invasive adenocarcinoma cannot be made by small biopsy or cytology specimens. Conclusion There is a need to work toward a mutual understanding and consensus between pathologists, clinicians, and researchers with the use of the term BAC versus adenocarcinoma. Future studies should make some attempt to quantitate these components and/or other features such as size of scar, size of invasive component, or pattern of invasion. Hopefully, this work will allow definition of a category of adenocarcinoma, mixed subtype with predominant BAC/minimal invasion and a favorable prognosis.
BACKGROUND
Gastrointestinal stromal tumors (GISTs) are a specific clinicopathologic entity characterized by activating mutations in the c-KIT gene. These mutations are associated with increased immunohistochemical staining for the c-KIT protein. Because many GISTs display a definitive response to the KIT inhibitor imatinib, accurate diagnosis of these neoplasms is of great clinical importance. GISTs are the most common mesenchymal neoplasms of the digestive tract and show lineage differentiation along the lines of the interstitial cells of Cajal. The cytomorphology of GISTs has been well described, but the cytologic features are not entirely specific and immunohistochemical staining is frequently used to confirm the diagnosis. However, KIT protein positivity established by immunohistochemistry (IHC) may be unreliable in some instances because of a small number of KIT-negative GISTs and immunohistochemical KIT positivity in some non-GIST spindle cell neoplasms of the gastrointestinal tract. Antigen retrieval may be the cause of this spurious positivity. Recently, the demonstration of KIT and PDGFRA mutations has been shown to be more reliable in establishing the diagnosis of GIST than IHC.METHODS
High resolution amplicon melting analysis was performed in a series of eight gastrointestinal stromal tumors sampled by fine needle aspiration (FNA).RESULTSIn five of eight cases, adequate material was obtained for mutational analysis. In four of these, mutations in the c-KIT gene were detected, and in the fifth case a mutation in the PDGFRA gene was detected.CONCLUSIONS
It appears that high resolution amplicon melting analysis can be successfully performed on material obtained by FNA and will show either KIT for PDGFR mutations in the majority of GIST FNA specimens. Cancer (Cancer Cytopathol) 2005. © 2005 American Cancer Society.
The protein-kinase family is the most frequently mutated gene family found in human cancer and faulty kinase enzymes are being investigated as promising targets for the design of antitumour therapies. We have sequenced the gene encoding the transmembrane protein tyrosine kinase ERBB2 (also known as HER2 or Neu) from 120 primary lung tumours and identified 4% that have mutations within the kinase domain; in the adenocarcinoma subtype of lung cancer, 10% of cases had mutations. ERBB2 inhibitors, which have so far proved to be ineffective in treating lung cancer, should now be clinically re-evaluated in the specific subset of patients with lung cancer whose tumours carry ERBB2 mutations.
BCR-ABL is a constitutively activated tyrosine kinase that causes chronic myeloid leukemia (CML). Since tyrosine kinase activity is essential to the transforming function of BCR-ABL, an inhibitor of the kinase could be an effective treatment for CML.
We conducted a phase 1, dose-escalating trial of STI571 (formerly known as CGP 57148B), a specific inhibitor of the BCR-ABL tyrosine kinase. STI571 was administered orally to 83 patients with CML in the chronic phase in whom treatment with interferon alfa had failed. Patients were successively assigned to 1 of 14 doses ranging from 25 to 1000 mg per day.
Adverse effects of STI571 were minimal; the most common were nausea, myalgias, edema, and diarrhea. A maximal tolerated dose was not identified. Complete hematologic responses were observed in 53 of 54 patients treated with daily doses of 300 mg or more and typically occurred in the first four weeks of therapy. Of the 54 patients treated with doses of 300 mg or more, cytogenetic responses occurred in 29, including 17 (31 percent of the 54 patients who received this dose) with major responses (0 to 35 percent of cells in metaphase positive for the Philadelphia chromosome); 7 of these patients had complete cytogenetic remissions.
STI571 is well tolerated and has significant antileukemic activity in patients with CML in whom treatment with interferon alfa had failed. Our results provide evidence of the essential role of BCR-ABL tyrosine kinase activity in CML and demonstrate the potential for the development of anticancer drugs based on the specific molecular abnormality present in a human cancer.
Most patients with non-small-cell lung cancer have no response to the tyrosine kinase inhibitor gefitinib, which targets the epidermal growth factor receptor (EGFR). However, about 10 percent of patients have a rapid and often dramatic clinical response. The molecular mechanisms underlying sensitivity to gefitinib are unknown.
We searched for mutations in the EGFR gene in primary tumors from patients with non-small-cell lung cancer who had a response to gefitinib, those who did not have a response, and those who had not been exposed to gefitinib. The functional consequences of identified mutations were evaluated after the mutant proteins were expressed in cultured cells.
Somatic mutations were identified in the tyrosine kinase domain of the EGFR gene in eight of nine patients with gefitinib-responsive lung cancer, as compared with none of the seven patients with no response (P<0.001). Mutations were either small, in-frame deletions or amino acid substitutions clustered around the ATP-binding pocket of the tyrosine kinase domain. Similar mutations were detected in tumors from 2 of 25 patients with primary non-small-cell lung cancer who had not been exposed to gefitinib (8 percent). All mutations were heterozygous, and identical mutations were observed in multiple patients, suggesting an additive specific gain of function. In vitro, EGFR mutants demonstrated enhanced tyrosine kinase activity in response to epidermal growth factor and increased sensitivity to inhibition by gefitinib.
A subgroup of patients with non-small-cell lung cancer have specific mutations in the EGFR gene, which correlate with clinical responsiveness to the tyrosine kinase inhibitor gefitinib. These mutations lead to increased growth factor signaling and confer susceptibility to the inhibitor. Screening for such mutations in lung cancers may identify patients who will have a response to gefitinib.
Gefitinib (Iressa, Astra Zeneca Pharmaceuticals) is a tyrosine kinase inhibitor that targets the epidermal growth factor receptor
(EGFR) and induces dramatic clinical responses in nonsmall cell lung cancers (NSCLCs) with activating mutations within the
EGFR kinase domain. We report that these mutant EGFRs selectively activate Akt and signal transduction and activator of transcription
(STAT) signaling pathways, which promote cell survival, but have no effect on extracellular signal–regulated kinase signaling,
which induces proliferation. NSCLC cells expressing mutant EGFRs underwent extensive apoptosis after small interfering RNA–mediated
knockdown of the mutant EGFR or treatment with pharmacological inhibitors of Akt and STAT signaling and were relatively resistant to apoptosis induced
by conventional chemotherapeutic drugs. Thus, mutant EGFRs selectively transduce survival signals on which NSCLCs become dependent;
inhibition of those signals by gefitinib may contribute to the drug's efficacy.
The cytoplasmic serine/threonine kinase BRAF and receptor tyrosine kinases of the platelet-derived growth factor receptor (PDGFR) family are frequently activated in cancer by mutations of an equivalent amino acid. Structural studies have provided important insights into why these very different kinases share similar oncogenic hot spots and why the PDGFR juxtamembrane region is also a frequent oncogenic target. This research has implications for other kinases that are mutated in human tumours and for the treatment of cancer using kinase inhibitors.
We studied the diagnostic value of Cdx2 to distinguish mucinous bronchioloalveolar carcinoma from mucinous colorectal adenocarcinoma metastatic to the lung. We retrieved 92 via the hospital computer system, including 30 mucinous bronchioloalveolar carcinomas, 32 nonmucinous bronchioloalveolar carcinomas, and 30 mucinous colorectal adenocarcinomas metastatic to the lung. All cases were confirmed by clinical history and surgical resection with occasional immunohistochemical studies. Cases were stained with antibodies against Cdx2, thyroid transcription factor-1 (TTF-1), cytokeratin (CK) 7, and CK20. Bronchioloalveolar carcinoma, mucinous type, showed positive staining for Cdx2, TTF-1, CK7, and CK20 in 0 (0%), 5 (17%), 30 (100%), and 18 (60%) of 30 cases, respectively; nonmucinous tumors were positive in 0 (0%), 30 (94%), 32 (100%), and 0 (0%) of 32 cases, respectively. For colorectal adenocarcinoma, the positive staining for Cdx-2, TTF-1, CK7, and CK20 was 29 (97%), 0 (0%), 7 (23%), and 29 (97%) of 30 cases, respectively. Our results demonstrated Cdx2 as a sensitive and specific marker for differentiating metastatic colorectal adenocarcinoma from mucinous bronchioloalveolar adenocarcinoma.
Once a poorly defined pathologic oddity, in recent years, gastrointestinal stromal tumor (GIST) has emerged as a distinct oncogenetic entity that is now center stage in clinical trials of kinase-targeted therapies. This review charts the rapid progress that has established GIST as a model for understanding the role of oncogenic kinase mutations in human tumorigenesis. Approximately 80% to 85% of GISTs harbor activating mutations of the KIT tyrosine kinase. In a series of 322 GISTs (including 140 previously published cases) studied by the authors in detail, mutations in the KIT gene occurred with decreasing frequency in exons 11 (66.1%), 9 (13%), 13 (1.2%), and 17 (0.6%). In the same series, a subset of tumors had mutations in the KIT-related kinase gene PDGF receptor alpha (PDGFRA), which occurred in either exon 18 (5.6%) or 12 (1.5%). The remainder of GISTs (12%) were wild type for both KIT and PDGFRA. Comparative studies of KIT-mutant, PDGFRA-mutant, and wild-type GISTs indicate that there are many similarities between these groups of tumors but also important differences. In particular, the responsiveness of GISTs to treatment with the kinase inhibitor imatinib varies substantially depending on the exonic location of the KIT or PDGFRA mutation. Given these differences, which have implications both for the diagnosis and treatment of GISTs, we propose a molecular-based classification of GIST. Recent studies of familial GIST, pediatric GIST, and variant forms of GIST related to Carney's triad and neurofibromatosis type 1 are discussed in relationship to this molecular classification. In addition, the role of mutation screening in KIT and PDGFRA as a diagnostic and prognostic aid is emphasized in this review.
This study was undertaken to investigate the effects of epidermal growth factor receptor (EGFR) mutation and its downstream signaling on response and survival in non-small-cell lung cancer (NSCLC) patients treated with gefitinib.
For 90 consecutive NSCLC patients who had received gefitinib, EGFR mutation was analyzed by DNA sequencing of exons 18, 19, 21, and 23 in the EGFR tyrosine kinase domain. Expressions of phosphorylated (p) -Akt and p-Erk were determined via immunohistochemistry. Response rate, time to progression (TTP), and overall survival were compared between each group according to EGFR mutation, as well as p-Akt and p-Erk expression.
Seventeen patients (18.9%; 95% CI, 10.8 to 27.0) harbored EGFR mutations. These mutations include deletions in exon 19 in seven patients, L858R in six patients, G719A in three patients, and a novel A859T in one patient. Response rate in patients with EGFR mutation was 64.7% (11 of 17 patients; 95% CI, 42.0 to 87.4), in contrast to 13.7% (10 of 73 patients; 95% CI, 5.8 to 21.6) in patients without mutation (P < .001). Moreover, these 17 patients with EGFR mutation had significantly prolonged TTP (21.7 v 1.8 months; P < .001) and overall survival (30.5 v 6.6 months; P < .001) compared with the remaining 73 patients without mutation. Although no significant correlation was detected between EGFR mutation and expressions of p-Akt or p-Erk, p-Akt overexpression was associated with prolonged TTP in patients with EGFR mutation.
Our data further support the importance of EGFR mutation with regard to gefitinib sensitivity. In addition to its predictive role, EGFR mutation confers significant survival benefits on NSCLC patients treated with gefitinib.
Gefitinib and erlotinib are small molecules that selectively inhibit epidermal growth factor receptor (EGFR) tyrosine kinase activity. When these drugs were introduced into the clinic, the specific targets affected in human tumors were unknown. In April 2004, two groups reported that mutations in the tyrosine kinase domain of EGFR are strongly associated with gefitinib sensitivity in patients with non-small-cell lung cancer (NSCLC). We subsequently extended these findings and showed that such mutations are also associated with sensitivity to erlotinib. Here, we present current knowledge about EGFR mutations in the context of clinical trials involving gefitinib and erlotinib in NSCLC.
This article reviews the rationale for targeting EGFR, the development of gefitinib and erlotinib, the discovery of EGFR mutations, and subsequent studies to define the incidence, spectrum, and functions of EGFR mutations.
The discovery of EGFR mutations promises to alter the ways in which we consider and treat NSCLC.
This information can guide practitioners and help them inform their patients about EGFR mutations and their impact on the treatment of NSCLC.
To review recent advances in pathology and computed tomography (CT) of lung adenocarcinoma and bronchioloalveolar carcinoma (BAC).
A pathology/CT review panel of pathologists and radiologists met during a November 2004 International Association for the Study of Lung Cancer/American Society of Clinical Oncology consensus workshop in New York. The purpose was to determine if existing data was sufficient to propose modification of criteria for adenocarcinoma and BAC as newly published in the 2004 WHO Classification of Lung Tumors, and to address the pathologic/radiologic concept of diffuse/multicentric BAC.
Solitary small, peripheral BACs have an excellent prognosis. Most lung adenocarcinomas with a BAC pattern are not pure BAC, but rather adenocarcinoma, mixed subtype with invasive patterns. This applies to tumors presenting with a diffuse/multinodular as well as solitary nodule pattern. The percent of BAC versus invasive components in lung adenocarcinomas appears to be prognostically important. However, a consensus definition of "minimally invasive" BAC with a favorable prognosis could not be achieved. While recognition of a BAC component is possible, the diagnosis of BAC with exclusion of invasive adenocarcinoma cannot be made by small biopsy or cytology specimens.
There is a need to work toward a mutual understanding and consensus between pathologists, clinicians, and researchers with the use of the term BAC versus adenocarcinoma. Future studies should make some attempt to quantitate these components and/or other features such as size of scar, size of invasive component, or pattern of invasion. Hopefully, this work will allow definition of a category of adenocarcinoma, mixed subtype with predominant BAC/minimal invasion and a favorable prognosis.
The epidermal growth factor receptor (EGFR) has emerged as an attractive therapeutic target for patients with non-small-cell lung cancer (NSCLC). However, despite its almost universal presence in NSCLC tumors, therapeutic inhibition of EGFR has resulted in significant tumor regressions in only 10% to 20% of patients. Several investigations over the last 12 months have uncovered somatic mutations in EGFR that underlie the sensitivity to EGFR inhibitors. NSCLC tumors and cell lines with EGFR mutations are exquisitely sensitive to the EGFR tyrosine kinase inhibitors (TKIs), erlotinib and gefitinib, and are biologically distinct from other forms of NSCLC. Somatic mutations in EGFR are found more frequently in patients with adenocarcinomas, nonsmokers, patients of Asian ethnicity, and in females. EGFR mutation detection is now becoming clinically available and is being incorporated into clinical treatment decisions and into the design of future clinical trials. Mutations in K-ras, a mediator of EGFR signaling, are mutually exclusive with EGFR mutations, and are associated with resistance to EGFR TKIs. In addition, secondary mutations, conferring resistance to EGFR TKIs, in patients with primary EGFR mutations once sensitive to EGFR TKIs, are beginning to be identified. The frequency of EGFR mutations, their impact on NSCLC biology, clinical treatment, and clinical trial design, as well as methods and limitations for mutation detection, will be reviewed.
To correlate epidermal growth factor receptor (EGFR) protein overexpression, as assessed by immunohistochemistry, with EGFR gene amplification determined by fluorescence in situ hybridization in a series of gliomas.
Forty-seven central nervous system gliomas, including 34 cases of glioblastoma multiforme, 3 oligodendrogliomas, 4 juvenile pilocytic astrocytomas and 5 low grade astrocytomas, were obtained from the files of the University of Utah Pathology Department. In each case a representative paraffin block was selected, and EGFR protein expression was quantified using immunohistochemistry. EGFR gene amplification status was determined by fluorescence in situ hybridization.
EGFR protein overexpression was detected in 9 cases of glioblastoma multiforme. EGFR gene amplification was present in 7 of these cases. Both nonamplified glioblastomas demonstrated only 2+ overexpression of EGFR protein. None of the low grade, pilocytic or anaplastic astrocytomas demonstrated either EGFR protein overexpression or gene amplification.
EGFR protein overexpression is closely associated with gene amplification. Seventy-eight percent of cases showing protein overexpression demonstrated gene amplification. All cases of central nervous system neoplasms showing protein overexpression but lacking gene amplification were associated with only 2+ protein overexpression. All central nervous system neoplasms demonstrating gene amplification and/or overexpression were high grade neoplasms.
Activating mutations in the BRAF kinase have been reported in a large number of cases of malignant melanoma. This suggests that therapy with specific RAF kinase inhibitors may find use in treating this disease. If the response to RAF kinase inhibition is dependent on the presence of an activated BRAF protein, it will be necessary to evaluate cases of malignant melanoma for the presence or absence of BRAF mutations. High-resolution amplicon melting analysis is able to detect single base-pair changes in DNA isolated from paraffin-embedded tissue sections and obviates the need for direct DNA sequencing. Results can be available within 48 hours. In this report, we used high-resolution amplicon melting analysis to evaluate 90 cases of malignant melanoma for BRAF mutations. Of these 90 cases, 74 were metastatic melanomas, 12 were primary cutaneous melanomas, and 4 were in situ melanomas. BRAF activation mutations were found in 43 cases (48%). Forty-one of these mutations were in exon 15. The mutations in exon 15 included V600E (34 cases), V600K (6 cases), and V600R (1 case). Two activating mutations were found in exon 11, G469V and G469R. The presence or absence of a BRAF mutation in the junctional component of an invasive melanoma was maintained in the invasive component. We also evaluated these 90 cases, as well as an additional 10 cases (total of 100) for the expression of c-kit. The majority of invasive and metastatic malignant melanomas did not express c-kit, although all in situ lesions and the junctional components of invasive lesions were strongly c-kit positive. Surprisingly, 2 cases of metastatic malignant melanoma (2%) showed strong and diffuse c-kit expression and contained a c-kit-activating mutation, L576P, as detected by high-resolution amplicon melting analysis and confirmed by direct DNA sequencing. These 2 c-kit mutation-positive cases did not contain BRAF mutations. The presence of a c-kit-activating mutation in metastatic malignant melanoma suggests that a small number of melanomas may progress by a somatic mutation of the c-kit gene. The presence of BRAF- and c-kit-activating mutations in malignant melanoma suggests new approaches to treating this disease involving specific tyrosine kinase inhibitors may prove worthwhile and that mutation analysis by high-resolution melting analysis might help guide therapy.
To evaluate epidermal growth factor receptor (EGFR) mutations and copy number as predictors of clinical outcome in patients with non-small-cell lung cancer (NSCLC) receiving gefitinib.
Sixty-six patients with NSCLC who experienced relapse after surgery and received gefitinib were included. Direct sequencing of exons 18 to 24 of EGFR and exons 18 to 24 of ERBB2 was performed using DNA extracted from surgical specimens. Pyrosequencing and quantitative real-time polymerase chain reaction were performed to analyze the allelic pattern and copy number of EGFR.
Thirty-nine patients (59%) had EGFR mutations; 20 patients had deletional mutations in exon 19, 17 patients had missense mutations (L858R) in exon 21, and two patients had missense mutations (G719S or G719C) in exon 18. No mutations were identified in ERBB2. Response rate (82% [32 of 39 patients] v 11% [three of 27 patients]; P < .0001), time to progression (TTP; median, 12.6 v 1.7 months; P < .0001), and overall survival (median, 20.4 v 6.9 months; P = .0001) were significantly better in patients with EGFR mutations than in patients with wild-type EGFR. Increased EGFR copy numbers (> or = 3/cell) were observed in 29 patients (44%) and were significantly associated with a higher response rate (72% [21 of 29 patients] v 38% [14 of 37 patients]; P = .005) and a longer TTP (median, 9.4 v 2.6 months; P = .038). High EGFR copy numbers (> or = 6/cell) were caused by selective amplification of mutant alleles.
EGFR mutations and increased copy numbers were significantly associated with better clinical outcome in gefitinib-treated NSCLC patients.
Bronchioloalveolar carcinoma (BAC) and adenocarcinomas with BAC features seem to be increasing in incidence, particularly in younger, never-smoking women. Epidermal growth factor receptor (EGFR) inhibitors demonstrated response rates of 20% to 30% in patients with advanced BAC subtypes, but selection methods for patient therapy are not established.
EGFR and HER2 gene copy numbers were assessed by fluorescence in situ hybridization (FISH) in 81 patients treated with gefitinib 500 mg/d (Southwest Oncology Group protocol S0126) and were correlated to treatment outcome. Tumors were classified into two main strata: FISH-positive (high polysomy/gene amplification) and FISH-negative (disomy/low polysomy).
In 81 patients, the median survival time for EGFR/FISH-negative patients was 8 months and not yet reached for FISH-positive patients (but approaching 18 months; hazard ratio [HR] = 2.02; P = .042). Median progression-free survival time for EGFR/FISH-positive patients was 9 months versus 4 months for the FISH-negative patients (HR = 1.67; P = .072). In multivariate analysis, EGFR copy number by FISH remained a significant predictive factor for survival after accounting for smoking status, sex, histology, and performance status. Fifty-five patients were evaluated for response using Response Evaluation Criteria in Solid Tumors Group, and 12 of 19 EGFR/FISH-positive patients (63%) demonstrated disease control versus 14 (39%) of 36 patients in the FISH-negative group (P = .087). No association was found between HER2 gene copy number and response (n = 39 patients) or survival (n = 56 patients; P > .10).
Increased EGFR gene copy number detected by FISH is associated with improved survival after gefitinib therapy in patients with advanced BAC, suggesting FISH methodology can be used to assess survival potential in patients treated with EGFR tyrosine kinase inhibitors.
Amplification of the HER2 oncogene in breast cancer identifies patients who are likely to respond to anti-HER2 mAb therapy. Current clinical practice dictates that all breast cancers first undergo HER2 screening by IHC. Strongly positive (3+ on a 0-to-3+ scale) IHC cases are considered as HER2-amplified tumors and are not evaluated further because of the strong correlation between HER2 gene amplification as measured by FISH and 3+ IHC. This strong correlation has recently been questioned, and some data suggest that over 50% of 3+ IHC HER2 immunostains may not be due to HER2 gene amplification. To help resolve this discrepancy, the authors developed a quantitative PCR assay for HER2. Quantitative PCR was used to determine the amount of HER2 DNA relative to a control gene, IF2 (eukaryotic translation initiation factor, 2p11.1-q11.1). The PCR assay is performed on genomic DNA isolated from paraffin-embedded breast cancer tissue. The PCR assay developed is a monoplex assay in which the HER2 and IF2 PCRs are performed in separate cuvettes. Cases of HER2 FISH amplified breast cancer and HER2 FISH nonamplified breast cancer were chosen for study by monoplex HER2 PCR. HER2 overexpression was evaluated by IHC. Twenty-two cases of HER2-positive and 22 cases of HER2-negative breast cancer, as determined by FISH, were assayed for HER2 by PCR and IHC. Sixteen of the 44 cases were interpreted as 3+ IHC. All 16 showed HER2 amplification by PCR and 15 showed HER2 amplification by FISH. One FISH negative case was found to be HER2 amplified by PCR and showed 3+ IHC stain, suggesting the FISH result in this case was underinterpreted. Two FISH positive cases were found to be negative by PCR and negative in IHC as well, suggesting the FISH result in these cases was overinterpreted. The authors conclude that 3+ IHC membrane staining correctly identifies neoplasms showing HER2 gene amplification. Monoplex HER2 PCR may offer significant advantages over both IHC and FISH for HER2 testing in breast cancer.
Detection of c-kit–activating mutations in gastrointestinal stromal tumors by high resolution amplicon melting analysis
- Willmore
EGF receptor gene mutations are common in lung cancers from “never smokers” and are associated with sensitivity of tumors to gefitinib and erlotinib
- Pao
Predictive and prognostic impact of epidermal growth factor receptor mutation in non–small-cell lung cancer patients treated with gefitinib
- Han
Epidermal growth factor receptor gene mutations and increased copy numbers predict gefitinib sensitivity in patients with recurrent non–small-cell lung cancer
- Takano
Epidermal growth factor receptor in non–small-cell lung carcinomas: correlation between gene copy number and protein expression and impact on prognosis
- Hirsch
Correlation of HER2 gene amplification with immunohistochemistry in breast cancer as determined by a novel monoplex polymerase chain reaction assay
- Willimore-Payne
Usefulness of Cdx2 in separating mucinous bronchioloalveolar adenocarcinoma of the lung from metastatic mucinous colorectal adenocarcinoma
- Saad