Epidermal growth factor receptor mutations in lung cancer

The development and clinical application of inhibitors that target the epidermal growth factor receptor (EGFR) provide important insights for new lung cancer therapies, as well as for the broader field of targeted cancer therapies. We review the results of genetic, biochemical and clinical studies focused on somatic mutations of EGFR that are associated with the phenomenon of oncogene addiction, describing 'oncogenic shock' as a mechanistic explanation for the apoptosis that follows the acute treatment of susceptible cells with kinase inhibitors. Understanding the genetic heterogeneity of epithelial tumours and devising strategies to circumvent their rapid acquisition of resistance to targeted kinase inhibitors are essential to the successful use of targeted therapies in common epithelial cancers.     

Epidermal growth factor receptor mutations in small cell lung cancer

PURPOSE: The vast majority of epidermal growth factor receptor (EGFR) mutations occur in lung adenocarcinoma, and even rare cases of other subtypes with this mutation, such as adenosquamous cell carcinoma, are associated with adenocarcinoma histology. According to this adenocarcinoma-specific nature of EGFR mutation, analysis of EGFR mutations with small cell lung cancers (SCLC) may provide a clue to its histogenesis. EXPERIMENTAL DESIGN: The mutational status of the EGFR gene was accessed in a cohort of 122 patients with SCLC; all patients were from a single institute. When the EGFR mutated, its gene copy number was also examined. RESULTS: EGFR mutations were detected in five SCLCs (4%). The patients were mainly in the light smoker and histologic combined subtype. All but one of the tumors harbored gene amplifications. Notably, in three tumors of the combined SCLC subtype, both components of adenocarcinoma and SCLC harbored an EGFR mutation, whereas gene amplification was detected only in the adenocarcinoma component. A partial response was achieved in a patient (with an EGFR mutation) who was treated with gefitinib. CONCLUSIONS: Although EGFR mutations are rare in SCLC, a combined subtype of SCLC with adenocarcinoma in light smokers may have a chance of harboring EGFR mutations. For patients with an EGFR mutation, EGFR tyrosine kinase inhibitor can be a treatment option. In terms of molecular pathogenesis, it is suggested that some SCLCs may have developed from pre-existing adenocarcinomas with EGFR mutations, but the development may not be simply linear, taking into consideration the discordant distribution of EGFR amplification.     

Epidermal growth factor receptor mutations in patients with non-small cell lung cancer

A year has passed since mutations of the tyrosine kinase domain of the epidermal growth factor receptor (EGFR) were discovered in patients with non-small cell lung cancer (NSCLC) who had dramatic clinical responses to treatment with gefitinib. Additional laboratory and clinical studies have provided further insight into the biological impact of EGFR mutations in cell culture experiments and in patients with NSCLC. In vitro characterizations of NSCLC cell lines and host cell lines transfected with these mutant and wild-type EGFR show that most cell lines with mutated EGFR are growth-inhibited by 10- to 100-fold lower concentrations of gefitinib and erlotinib compared with wild-type EGFR. NSCLC lines with mutations of the EGFR treated with concentrations of gefitinib and erlotinib that are achievable in the plasma undergo apoptosis rather than growth arrest. Retrospective studies of patients with NSCLC-treated gefitinib have reported a close association between EGFR mutations, increased chance of clinical response and longer survival. This review will provide information on the impact of EGFR mutations on gefitinib and erlotinib treatment by in vitro experiments, the outcome of NSCLC patients with these mutations when treated with gefitinib and erlotinib, and the subsets of patients with NSCLC in whom these mutations arise.     

Epidermal growth factor receptor targeting in cancer

The epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase of the ErbB family that is abnormally activated in many epithelial tumors. Several mechanisms lead to the receptor's aberrant activation that is observed in cancer, including receptor overexpression, mutation, ligand-dependent receptor dimerization, and ligand-independent activation. Two classes of anti-EGFR agents are currently approved for the treatment of patients with cancer: cetuximab, a monoclonal antibody directed at the extracellular domain of the receptor, and gefitinib and erlotinib, oral, low-molecular-weight (MW), adenosine triphosphate (ATP)-competitive inhibitors of the receptor's tyrosine kinase. Anti-EGFR monoclonal antibodies have demonstrated activity in the therapy of advanced colorectal carcinoma and in a variety of epithelial tumor types, including head and neck cancer and non-small cell lung cancer (NSCLC). The development of low MW, anti-EGFR tyrosine kinase inhibitors (TKIs) has been focused until recently on NSCLC, although responses have been reported for other types of cancer. Erlotinib was the only agent approved based on demonstrating improved survival, which was observed in patients with advanced NSCLC who previously had been treated with chemotherapy. Recent major advances in the EGFR field include the discovery of EGFR somatic mutations in NSCLC that have important implications for biology, treatment, clinical trial design, and methods for mutation detection. Clinical and survival benefits with anti-EGFR agents have been demonstrated in additional tumor types such as head and neck and pancreatic carcinomas. New agents with clinical activity are entering the clinic and new combinatorial approaches with anti-EGFR agents are being explored. Major efforts are, belatedly, attempting to identify molecular markers that can predict patients more likely to respond to anti-EGFR therapy.     

非小细胞肺癌组织表皮生长因子受体基因突变的临床意义

目的探讨非小细胞肺癌(NSCLC)肿瘤组织表皮生长因子受体(EGFR)基因突变及其相关因素.方法抽取80例手术切除肿瘤组织DNA,采用巢式PCR方法对编码EGFR基因的第18、19和21外显子片段进行扩增和测序,用Chromas软件分析基因突变或缺失.结果21例肿瘤组织存在EGFR基因突变或缺失,发生率为26.25%,其中13例为EGFR第19外显子阅读框内多核苷酸的缺失,8例为第21外显子2 573位核苷酸点突变.这些突变均为杂合子型.肺腺癌突变率为42.10%(16/38),显著高于鳞癌的9.68%(3/31)和鳞腺混合癌的18.2%(2/11)(χ2=9.702,P ＜0.01);女性患者突变率为48.28%(14/29),显著高于男性患者的13.73%(7/51)(χ2=11.4,P＜0.01);不吸烟者突变率为40%(16/40),显著高于吸烟者的12.50%(5/40)(χ2=7.812,P＜0.01).EGFR基因突变与患者年龄、TNM分期等因素无关.Logistic回归分析提示患者性别和组织类型是影响EGFR突变的2个主要因素.结论NSCLC存在EGFR基因的突变或缺失,其中以女性、腺癌和不吸烟患者突变率较高.     

Epidermal growth factor receptor activation confers resistance to lenvatinib in thyroid cancer cells

Thyroid cancer is the most common endocrine malignancy. A multitargeted tyrosine kinase inhibitor, lenvatinib, has been used for the treatment of advanced thyroid cancer. To elucidate the mechanism of resistance to lenvatinib in thyroid cancer cells, we established lenvatinib‐resistant sublines and analyzed the molecular mechanisms of resistance. Two thyroid cancer cell lines (TPC‐1 and FRO) were used, and resistant sublines for lenvatinib (TPC‐1/LR, FRO/LR) were established. In TPC‐1/LR, the phosphorylation of epidermal growth factor receptor (EGFR), extracellular signal‐regulated kinase (ERK), and Akt was enhanced whereas in FRO/LR, the phosphorylation of EGFR and downstream signal transduction molecules was not enhanced. The addition of epidermal growth factor decreased sensitivity to lenvatinib in TPC‐1 and FRO. The combination of EGFR inhibitors lapatinib and lenvatinib significantly inhibited the growth of TPC‐1/LR in both in vitro and mouse xenograft models. Short‐term exposure to lenvatinib enhanced the phosphorylation of EGFR in six thyroid cancer cell lines regardless of their histological origin or driver gene mutations; however, phosphorylation of ERK was enhanced in all cells except TPC‐1. A synergistic growth‐inhibitory effect was observed in three thyroid cancer cell lines, including intrinsically lenvatinib‐resistant cells. The results indicate that signal transduction via the EGFR pathway may be involved in the development of lenvatinib resistance in thyroid cancer cells. The inhibition of the EGFR pathway simultaneously by an EGFR inhibitor may have therapeutic potential for overcoming lenvatinib resistance in thyroid cancer.     

Epidermal growth factor receptor gene mutations in papillary thyroid carcinoma

Recent studies have indicated that somatic mutations in the epidermal growth factor receptor (EGFR) gene have been identified in a subset of patients with nonsmall‐cell lung cancer (NSCLC) and are associated with sensitivity to the EGFR‐tyrosine‐kinase inhibitors. These mutations have been reported to be almost exclusively found in a pulmonary adenocarcinoma subgroup of NSCLC, with a low frequency in other solid tumors. We describe a patient with advanced‐stage papillary thyroid carcinoma (PTC) whose disease had been diagnosed as pulmonary adenocarcinoma at first, and who had a marked response to the EGFR‐tyrosine‐kinase inhibitor, gefitinib. An in‐frame deletion in exon 19 that eliminated 4 amino acids at positions 746 through 750, which is one of the common drug‐sensitive mutations in pulmonary adenocarcinoma, and a serine‐to‐proline substitution at codon 752, were found in a tumor specimen of the patient. We subsequently searched for mutations in the EGFR tyrosine kinase domain in primary tumors from 23 patients with PTC, and drug‐sensitive mutations commonly observed in pulmonary adenocarcinoma were found in 7 of these patients. Our observation of a high frequency of the EGFR‐activating mutations in PTC suggests that the EGFR mutation may be an important event in the development of PTC. EGFR gene amplification, also considered to be a predictor of response to EGFR‐tyrosine‐kinase inhibitors, was evaluated by fluorescence in situ hybridization (FISH); however, only 1 FISH‐positive tumor was detected. Our data suggest that EGFR‐tyrosine‐kinase inhibitors may deserve consideration in the treatment of a subset of patients with PTC, just as with pulmonary adenocarcinoma. © 2008 Wiley‐Liss, Inc.     

Epidermal growth factor receptor (EGFR) status and K-Ras mutations in colorectal cancer

Background: In advanced colorectal cancer, K-Ras somatic mutations predict resistance to mAbs targeting epidermal growth factor receptor (EGFR). Relationships between K-Ras mutations and EGFR status have not been examined so far. We analyzed relationships between K-Ras mutations and EGFR tumoral status based on EGFR germinal polymorphisms, gene copy number and expression.Methods: Eighty colorectal tumors (stage 0–IV) and 39 normal mucosas were analyzed. K-Ras mutations at codons 12 and 13 were detected by a sensitive enrichment double PCR–restriction fragment length polymorphism (RFLP) assay. EGFR gene polymorphisms at positions -216G>T, -191C>A and 497Arg>Lys were analyzed (PCR–RFLP), along with CA repeat polymorphism in intron 1 (fluorescent genotyping) and EGFR gene copy number (PCR amplification). EGFR expression was quantified by Scatchard binding assay.Results: The number of EGFR high-affinity sites, dissociation constant (Kd), gene copy number, intron 1, -216G>T, -191C>A or 497Lys>Arg genotypes was not different between K-Ras-mutated or K-Ras-non-mutated tumors. No relationship was observed between any of the analyzed EGFR genotypes and EGFR expression. EGFR expression was not related to gene copy number. EGFR gene copy number in tumor and normal tissue was not correlated. The mean value of the tumor/normal mucosa gene copy number ratio was 1.16.Conclusions: Present data clearly show that EGFR status is independent of K-Ras mutations in colorectal tumors.     

Epidermal growth factor receptor in human breast cancer

For the purpose of demonstrating the relationship between epidermal growth factor receptor (EGFR) content in the tumor and histopathologic characteristics, 45 women with breast cancer who underwent mastectomy were analyzed. EGFR content was measured by competitive binding assay using 125I, while EGFR was detected by immunocytochemical staining. Tumors with more than 1 fmol/mg protein EGFR were defined as positive, and a good correlation between competitive binding assay and staining was observed. Seventeen of them (37.8%) had EGFR-positive tumors. Eight of the 17 EGFR-positive tumors (47.1%) were positive for estrogen receptor (ER), whereas 24 of the 28 EGFR-negative tumors (85.7%) were ER-positive. This inverse relation was statistically significant (chi 2; p less than 0.05). Twelve of the 17 EGFR-positive cases (70.6%) had axillary node involvements, against 11 of the 28 (39.3%) in the EGFR-negative cases. There was no difference in the size of primary tumor between the two groups. These results suggested that EGFR-positive tumors have more malignant potency than EGFR-negative tumors. In 8 cases, EGFR content in metastatic axillary nodes was compared with that in primary tumors. More EGFR content indicated in metastatic axillary nodes than in primary tumors without significant difference.     

Epidermal growth factor receptor inhibitors in cancer treatment

The epidermal growth factor receptor (EGFR) is a cellular transmembrane receptor with tyrosine kinase enzymatic activity which plays a key role in human cancer. EGFR-dependent signaling is involved in cancer cell proliferation, apoptosis, angiogenesis, invasion and metastasis. Targeting the EGFR is a valuable molecular approach in cancer therapy. Several anti-EGFR drugs are in Phase III clinical development as single agent or in combination with other anticancer modalities. Cetuximab (Erbitux), a chimeric human-mouse monoclonal immunoglobin (Ig)G1 antibody, which blocks ligand binding and functional activation of the EGFR, is currently registered in the USA, Switzerland and the European Union for the treatment of advanced, irinotecan-refractory colorectal cancer. Gefitinib, (Iressa), a small molecule EGFR-selective inhibitor of tyrosine kinase activity which blocks EGF autophosphorylation and activation, has been the first EGFR-targeting drug to be registered in 28 countries worldwide, including the USA, for the third-line treatment of chemoresistant non-small cell lung cancer patients. This review will focus on the preclinical background and on the clinical data with the anti-EGFR drugs in most advanced clinical development. Furthermore, a series of open clinical issues for the development of optimal strategies of using EGFR-targeting agents will be discussed.     

Epidermal growth factor receptor activating mutations in Spanish gefitinib-treated non-small-cell lung cancer patients.

BACKGROUND: North American and Japanese non-small-cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) activation via tyrosine kinase (TK) mutations respond dramatically to gefitinib treatment. To date, however, the frequency and effect of EGFR TK mutations have not been examined in European patients. PATIENTS AND METHODS: Eighty-three Spanish advanced NSCLC patients who had progressed after chemotherapy, were treated with compassionate use of gefitinib. Patients were selected on the basis of available tumor tissue. Tumor genomic DNA was retrieved from paraffin-embedded tissue obtained by laser capture microdissection. EGFR mutations in exons 19 and 21 were examined by direct sequencing. RESULTS: EGFR mutations were found in 10 of 83 (12%) of patients. All mutations were found in adenocarcinomas, more frequently in females (P=0.007) and non-smokers (P=0.01). Response was observed in 60% of patients with mutations and 8.8% of patients with wild-type EGFR (P=0.001). Time to progression for patients with mutations was 12.3 months, compared with 3.6 months for patients with wild-type EGFR (P=0.002). Median survival was 13 months for patients with mutations and 4.9 months for those with wild-type EGFR (P=0.02). CONCLUSIONS: EGFR TK mutational analysis is a novel predictive test for selecting lung adenocarcinoma patients for targeted therapy with EGFR TK inhibitors.     

Epidermal growth factor receptor mutations predict sensitivity to gefitinib in patients with non-small-cell lung cancer

Despite advances in chemotherapeutics, overall survival for advanced lung cancer patients remains poor. Consequently, efforts have focused on the use of targeted therapies to improve response rates and survival. The epidermal growth factor receptor (EGFR) is overexpressed in a variety of cancers, including lung, and may play a critical role in the pathogenesis of disease. Small molecule tyrosine kinase inhibitors, such as gefitinib (Iressa(R)), have response rates of between 10 and 27% in Phase II trials, and anecdotal reports of dramatic and sustained responses. Two recent studies published simultaneously, identified mutations in the ATP-binding cleft of the EGFR that are associated with clinical response to gefitinib. This finding has extraordinary implications and serves as a critical step toward individualized, patient-specific treatment plans based on the molecular constitution of the tumor of each individual.     

Epidermal growth factor receptor and K-Ras mutations and resistance of lung cancer to insulin-like growth factor 1 receptor tyrosine kinase inhibitors

BACKGROUND:

Most patients with nonsmall cell lung cancer (NSCLC) have responded poorly to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs). The authors investigated the involvement of insulinlike growth factor 1 receptor (IGF‐1R) signaling in primary resistance to EGFR TKIs and the molecular determinants of resistance to IGF‐1R TKIs.

METHODS:

Phosphorylated IGF‐1R/insulin receptor (pIGF‐1R/IR) was immunohistochemically evaluated in an NSCLC tissue microarray. The authors analyzed the antitumor effects of an IGF‐1R TKI (PQIP or OSI‐906), either alone or in combination with a small‐molecular inhibitor (PD98059 or U0126) or with siRNA targeting K‐Ras or mitogen‐activated protein kinase/extracellular signal‐regulated kinase kinase (MEK), in vitro and in vivo in NSCLC cells with variable histologic features and EGFR or K‐Ras mutations.

RESULTS:

pIGF‐1R/IR expression in NSCLC specimens was associated with a history of tobacco smoking, squamous cell carcinoma histology, mutant K‐Ras, and wild‐type (WT) EGFR, all of which have been strongly associated with poor response to EGFR TKIs. IGF‐1R TKIs exhibited significant antitumor activity in NSCLC cells with WT EGFR and WT K‐Ras but not in those with mutations in these genes. Introduction of mutant K‐Ras attenuated the effects of IGF‐1R TKIs on NSCLC cells expressing WT K‐Ras. Conversely, inactivation of MEK restored sensitivity to IGF‐TKIs in cells carrying mutant K‐Ras.

CONCLUSIONS:

The mutation status of both EGFR and K‐Ras could be a predictive marker of response to IGF‐1R TKIs. Also, MEK antagonism can abrogate primary resistance of NSCLC cells to IGF‐1R TKIs. Cancer 2012. © 2012 American Cancer Society.     

Epidermal growth factor receptor structural alterations in gastric cancer

Background  

EGFR overexpression has been described in many human tumours including gastric cancer. In NSCLC patients somatic EGFR mutations, within the kinase domain of the protein, as well as gene amplification were associated with a good clinical response to EGFR inhibitors. In gastric tumours data concerning structural alterations of EGFR remains controversial. Given its possible therapeutic relevance, we aimed to determine the frequency and type of structural alterations of the EGFR gene in a series of primary gastric carcinomas.     

Epidermal growth factor receptor mutations and response to chemotherapy in patients with non-small-cell lung cancer

BACKGROUND: The association of epidermal growth factor receptor (EGFR) mutations with the response to conventional cytotoxic chemotherapeutic agents in non-small-cell lung cancer patients has not been investigated. We retrospectively analyzed the associations between response to chemotherapy and molecular markers associated with gefitinib responsiveness including EGFR mutations. METHODS: EGFR (exons 18, 19 and 21) and K-ras mutations (exon 2) were studied by direct sequencing and p-Erk and p-Akt expressions were studied by immunohistochemistry in archival paraffin embedded tissues. Response rate (RR) and time-to-progression (TTP) of prior chemotherapy by platinum, paclitaxel and gemcitabine were analyzed with respect to the presence of EGFR and K-ras mutations, and p-Erk and p-Akt expressions. RESULTS: Of 90 patients investigated, 75 received platinums and 45 received paclitaxel as first-line chemotherapy agents. The RRS and TTPS of platinum- and paclitaxel-containing regimens were not affected by EGFR or K-ras mutations, nor by p-Erk or p-Akt expression. Fifty-seven patients received gemcitabine as first- or second-line chemotherapy. RR was not affected by EGFR or K-ras mutations or by p-Akt expression. However, all responders to gemcitabine exhibited (+) p-Erk expression [RR 30.6% for p-Erk (+) versus 0% for p-Erk (-), P = 0.01]. TTP was not affected by EGFR or K-ras mutations or by p-Erk or p-Akt expression. CONCLUSIONS: EGFR mutations did not affect response to conventional chemotherapeutic agents, namely platinums, paclitaxel and gemcitabine. Our results also suggest that it may be undesirable to use gemcitabine in patients with tumors not expressing p-Erk.     

Epidermal growth factor and its receptor in cervical cancer

Epidermal growth factor (EGF) is an important growth factor regulating both normal and malignant cells. The present study analyzes the expression pattern of EGF and its receptor (EGF-R) in 424 cases of various stages of tumor progression in the uterine cervix. In all the samples studied, EGF and EGF-R expression was predominant in the basal or basaloid cells. Increased expression of the two proteins correlated with increasing histological abnormality (dysplasia). In invasive cancer, alteration of EGF expression was more evident than EGF-R. The expression pattern showed significant correlation in the basal and spinal cell layers. This increased expression of EGF observed in dysplastic and malignant cells may be due to overexpression of EGF-R and suggests its role in cellular proliferation.     

Epidermal growth factor receptor mutations detected by denaturing high‐performance liquid chromatography in nonsmall cell lung cancer

BACKGROUND:

Somatic mutations in the epidermal growth factor receptor (EGFR) kinase domain are associated with sensitivity to EGFR‐tyrosine kinase inhibitors (EGFR‐TKI) in patients with nonsmall cell lung cancer (NSCLC).

METHODS:

The authors tested the possibility that nucleotide sequencing may be poorly suited for detection of mutations in tumor samples and found that denaturing high‐performance liquid chromatography (dHPLC) was an efficient and more sensitive method for screening.

RESULTS:

These results suggested that some reports based on standard DNA sequencing techniques may have underestimated mutation rates. In the present report, the authors examined the relationship between the presence and type of EGFR mutations detected by dHPLC and various clinicopathologic features of NSCLC, including response to therapy with EGFR‐TKI. Among 251 patients with advanced disease, 100 individuals received EGFR‐TKI. Those whose tumors harbored a detectable EGFR kinase mutation were much more likely to have a partial response (PR) or stable disease (SD) with EGFR‐TKI therapy than patients whose tumor contained no mutation (80% vs 35%; P = .001). Among the individual genotype subgroups, the frequency of a PR or SD was significantly different between patients with an exon 19 deletion compared with those with no detectable mutation (86% vs 35%; P < .001). Furthermore, patients whose tumors expressed an exon 19 mutant EGFR isoform exhibited a trend toward better EGFR‐TKI response (86% vs 67%; P = .171) and improved survival compared with patients whose tumors expressed an exon 21 mutation.

CONCLUSIONS:

Our findings warrant confirmation in large prospective trials and exploration of the biological mechanisms of the differences between mutation types. Cancer 2010. © 2010 American Cancer Society.     

Epidermal growth factor receptor mutations are associated with gefitinib sensitivity in non-small cell lung cancer in Japanese

The protein-kinase family is the most frequently mutated gene family found in human cancer. Gefitinib, an ATP-competitive inhibitor of epidermal growth factor receptor (EGFR), also appears to be particularly effective in adenocarcinoma of the lung and in patients without smoking history. To determine whether lung tumors sensitive to gefitinib contained mutations within the tyrosine kinase (TK) domain of EGFR, we screened exons 18-23 of EGFR of tumors in 20 patients with non-small cell lung cancer (NSCLC) who had been treated with gefitinib. Nine (45%) tumors had TK domain mutations. All mutations were observed in adenocarcinoma. Seven (77.8%) of 9 cases with mutated types showed sensitivity to gefitinib, while no cases of 11 with wild type showed gefitinib sensitivity. Such mutations were more frequently observed in patients who had never smoked (5/8 or 62.5%) than in smokers (4/12 or 33.3%). The patients with mutations of EGFR to have a more favorable prognosis than those with wild type (p=0.033). These data show that adenocarcinomas from patients who had never smoked comprise a specific subset of patients with NSCLC sensitive to gefitinib treatment.