Pharmacogenetics of EGFR in lung cancer: perspectives and clinical applications

Lung cancer is a lethal disease, and most cases have already disseminated at the time of diagnosis. Driver mutations in the EGFR tyrosine kinase domain (mainly deletions in exon 19 and L858R mutation in exon 21) have been identified in lung adenocarcinomas, mostly in never smokers, at frequencies of 20-60%. The EGFR tyrosine kinase inhibitors (TKIs) gefitinib or erlotinib attain a response rate of 70% and progression-free survival of 9-13 months, although there are subgroups of patients with long-lasting remissions. No significant correlation between EGFR overexpression and response to treatment has been found, while controversial results have been reported regarding EGFR gene amplification. The pretreatment presence of the T790M mutation, initially identified as an acquired resistance mutation to treatment with EGFR TKIs, has also been reported and may indicate a genetically distinct disease. Finally, other genetic factors, such as mRNA expression of BRCA1 and components of the NF-κB pathway, can modulate response to EGFR TKIs in EGFR-mutated patients.     

Structure-Based Approach for the Discovery of Pyrrolo[3,2-d]pyrimidine-Based EGFR T790M/L858R Mutant Inhibitors

相似文献   

Oxopyrido[2,3-d]pyrimidines as Covalent L858R/T790M Mutant Selective Epidermal Growth Factor Receptor (EGFR) Inhibitors

相似文献   

阿美替尼治疗非小细胞肺癌的研究进展

肺癌是全球癌症相关死亡的最常见原因,其中85%为非小细胞肺癌(non-small-cell lung cancer,NSCLC),表皮生长因子受体(epidermal growth factor receptor,EGFR)是治疗晚期NSCLC最重要的靶点之一。第一、二代EGFR酪氨酸激酶抑制剂(EGFR-tyrosine kinase inhibitor,EGFR-TKI)一直是晚期EGFR突变NSCLC患者的标准治疗方法,但获得性耐药几乎不可避免,主要耐药原因为T790M突变。阿美替尼是中国首个自主研发的第三代EGFR-TKI,对包括L858R和19号外显子缺失在内的EGFR敏感突变,以及T790M耐药突变均具有活性,同时保留野生型EGFR,克服了第一、二代EGFR-TKI的耐药性和选择性问题,其临床前和临床研究均显示出良好的有效性与安全性,为我国NSCLC患者提供了新的用药选择。本综述对阿美替尼的结构、作用机制、临床前研究、药动学,在NSCLC治疗中的临床疗效、安全性,以及与其他第三代EGFR-TKI的比较进行了总结,为该药的临床使用及未来的探索研究提供参考。     

Identifying nonsmall‐cell lung tumours bearing the T790M EGFR TKI resistance mutation using PET imaging

Specific mutations significantly affect response to epidermal growth factor tyrosine kinase inhibitor (EGFR‐TKI) treatment in lung cancer patients. Identifying patients with these mutations remains a major clinical challenge. EGFR T790M mutation, which conveys resistance to in the present study, [¹⁸F]FEWZ was assessed in vitro to determine efficacy relative to the starting compound and in vivo to measure the biodistribution and specificity of binding to EGFR wild‐type, L858R and T790M bearing tumours. [¹⁸F]FEWZ is the first evidence of a radiolabeled third generation anilinopyrimidine‐derived tyrosine kinase inhibitor targeting T790M mutation bearing tumours in vivo.     

Targeting the EGFR T790M mutation in non-small-cell lung cancer

Introduction: The presence of activating mutations of the epidermal growth factor receptor (EGFR) is predictive of response to first- and second-generation tyrosine kinase inhibitors (TKIs) in patients with advanced non-small-cell lung cancer (NSCLC). However, patients that initially respond to these drugs inexorably become resistant. The T790M mutation in the exon 20 of the EGFR is the main mechanism of resistance to EGFR TKIs occurring in over 50% of the cases. Third generation EGFR TKIs have been shown to be active in patients who progressed after TKI treatment and carry the T790M mutation.

Areas covered: This review is focused on the implications of tumor heterogeneity for targeting the T790M in patients with NSCLC.

Expert opinion: Pre-clinical and clinical data suggest that the T790M is heterogeneously expressed in tumors that become resistant to first- and second-generation EGFR TKIs. These findings have important implications for the molecular diagnostic of the T790M mutation. Indeed, the analysis of both the circulating free tumor DNA (ctDNA) isolated from plasma and the tumor tissue might provide complimentary information to identify patients carrying the T790M mutation. However, further studies are needed to better understand the influence of tumor heterogeneity on the activity of drugs targeting the T790M.     

Targeting DNA-PK overcomes acquired resistance to third-generation EGFR-TKI osimertinib in non-small-cell lung cancer

The third-generation of epidermal growth factor receptor(EGFR)tyrosine kinase inhibitors(TKIs),represented by osimertinib,has achieved remarkable clinical outcomes in the treatment of non-small-cell lung cancer(NSCLC)with EGFR mutation.However,resistance eventually emerges in most patients and the underlying molecular mechanisms remain to be fully understood.In this study,we generated an osimertinib-acquired resistant lung cancer model from a NSCLC cell line H1975 harboring EGFR L858R and T790M mutations.We found that the capacity of DNA damage repair was compromised in the osimertinib resistant cells,evidenced by increased levels ofγH2AX and higher intensity of the comet tail after withdrawal from cisplatin.Pharmacological inhibiting the activity or genetic knockdown the expression of DNA-PK,a key kinase in DNA damage response(DDR),sensitized the resistant cells to osimertinib.Combination of osimertinib with the DNA-PK inhibitor,PI-103,or NU7441,synergistically suppressed the proliferation of the resistant cells.Mechanistically,we revealed that DNA-PK inhibitor in combination with osimertinib resulted in prolonged DNA damage and cell cycle arrest.These findings shed new light on the mechanisms of osimertinib resistance in the aspect of DNA repair,and provide a rationale for targeting DNA-PK as a therapeutic strategy to overcome osimertinib-acquired resistance in NSCLC.     

Rociletinib,a third generation EGFR tyrosine kinase inhibitor: current data and future directions

Introduction: Major advances have been made since the discovery of driver mutations and their targeted therapies, especially in the treatment of patients with epidermal growth factor receptor (EGFR) mutations. Despite their initial efficacy in the majority of the patients with such driver mutations, all targeted therapies are limited by the eventual development of resistance mechanisms.

Areas Covered: EGFR T790M mutation is a common resistance mechanism after treatment with first or second generation EGFR tyrosine kinase inhibitors (TKI). Rociletinib is one of the third generation EGFR TKIs with activity against T790M and activating EGFR mutations while sparing the wild-type EGFR. In this review, we discuss the current understanding and available data on rociletinib, including the side effects associated with the medication. We will also review the BEAMing plasma test to detect T790M mutation without the need for repeat biopsy. Lastly, we review the potential resistance mechanisms after progression on rociletinib, and future directions.

Expert Opinion: It is important to note that there are other 3^rd generation EGFR TKIs with activity against T790M already approved by the US FDA (osimertinib) and many others in development. Future research will focus on figuring out which patients can benefit the most from a particular medication with minimal side effects, and further resistance mechanisms after rociletinib.     

Design, synthesis, and biological evaluation of novel conformationally constrained inhibitors targeting epidermal growth factor receptor threonine⁷⁹⁰ → methionine⁷⁹⁰ mutant

The EGFR(T790M) mutant contributes approximately 50% to clinically acquired resistance against gefitinib or erlotinib. However, almost all the single agent clinical trials of the second generation irreversible EGFR inhibitors appear inadequate to overcome the EGFR(T790M)-related resistance. We have designed and synthesized a series of 2-oxo-3,4-dihydropyrimido[4,5-d]pyrimidinyl derivatives as novel EGFR inhibitors. The most potent compounds, 2q and 2s, inhibited the enzymatic activities of wild-type and mutated EGFRs, with IC(50) values in subnanomolar ranges, including the T790M mutants. The kinase inhibitory efficiencies of the compounds were further validated by Western blot analysis of the activation of EGFR and downstream signaling in cancer cells harboring different mutants of EGFR. The compounds also strongly inhibited the proliferation of H1975 non small cell lung cancer cells bearing EGFR(L858R/T790M), while being significantly less toxic to normal cells. Moreover, 2s displayed promising anticancer efficacy in a human NSCLC (H1975) xenograft nude mouse model.     

Design and synthesis of tetrahydropyridothieno[2,3-d]pyrimidine scaffold based epidermal growth factor receptor (EGFR) kinase inhibitors: the role of side chain chirality and Michael acceptor group for maximal potency

HTS hit 7 was modified through hybrid design strategy to introduce a chiral side chain followed by introduction of Michael acceptor group to obtain potent EGFR kinase inhibitors 11 and 19. Both 11 and 19 showed over 3 orders of magnitude enhanced HCC827 antiproliferative activity compared to HTS hit 7 and also inhibited gefitinib-resistant double mutant (DM, T790M/L858R) EGFR kinase at nanomolar concentration. Moreover, treatment with 19 shrinked tumor in nude mice xenograft model.     

突变体富集PCR法检测非小细胞肺癌病理组织EGFR基因突变

目的：建立突变体富集PCR法检测非小细胞肺癌病理组织中的EGFR基因突变。方法：选取55例细支气管肺泡癌和59例非小细胞肺癌病理组织蜡块，提取基因组DNA，采用不同的突变体富集PCR法（PCR-PAGE和PCR-RLFP）检测EGFR基因常见的19和21外显予突变，并经过直接测序验证。结果：在59例非小细胞肺癌中共检测出EGFR基因突变22例,突变率为37．3％（22／59）。55例细支气管肺泡癌中共检测出24例基因突变，突变率为43．6％（24／55）。经直接测序验证，EGFR19外显予有3种类型缺失突变。EGFR21外显予的错义突变为L858R。结论：突变体富集PCR法准确、快速、经济，便于临床筛查非小细胞肺癌病理组织中的EGFR基因突变。     

EGFR基因突变与肿瘤靶向治疗

表皮生长因子受体(epidermal growth factor receptor,EGFR)属于受体酪氨酸激酶超家族,在多种恶性肿瘤中表达。配体与EGFR结合诱导形成二聚体和构象变化,活化酪氨酸激酶及信号转导途径,产生细胞增殖、侵润、转移及抗凋亡等效应。EGFR酪氨酸激酶抑制剂(tyrosine kinase inhibitors,TKIs)类靶向药物,如吉非替尼和厄洛替尼等已应用于临床。临床研究显示仅10%~30%患者对TKIs敏感,部分位于EGFR激酶结构域的活化突变与药物敏感性相关。检测EGFR基因突变有助于预测对药物敏感性和提高疗效。随着治疗绝大多数敏感的患者获得继发耐药性,其中约半数有继发突变T790M,降低药物对靶分子的亲和力,其他许多位于EGFR下游信号途径或旁激活途径的分子也参与耐药形成。因此,未来个体化用药和准确预测敏感性,不仅仅要分析EGFR基因,而且要综合考虑下游和其他信号途径的基因,如PI3K,K-RAS,BRAF,MET和PTEN等。     

Mechanisms of resistance to epidermal growth factor receptor tyrosine kinase inhibitors in patients with advanced non-small-cell lung cancer: clinical and molecular considerations

Non-Small-Cell Lung Cancer (NSCLC) with somatic mutations of the epidermal growth factor receptor (EGFR) is anticipated to respond to small-molecule tyrosine kinase inhibitors (TKIs) of the EGFR tyrosine kinase. There are, however, patients with EGFR mutated tumors who do not demonstrate tumor response. The most widely accepted mechanism of 'de novo' (inherent) resistance to these TKIs involves mutations of the KRAS gene. KRAS is a downstream mediator of EGFR-induced cell signaling, such mutations appear to be mutually exclusive from EGFR mutations in lung cancer. The first molecular modifier of resistance identified in patients who developed resistance (termed 'acquired resistance') to TK inhibition was a new acquired somatic EGFR mutation (T790M). Today there is an ever-growing series of molecular events that have recently come to the forefront to explain other instances of TKI resistance not attributable to T790M or KRAS. These include a number of molecules that interact with EGFR or form part of its downstream signaling pathway such as HER-2, IGFR-1, MET and B-RAF. Considering that the majority of studies carried out to date with respect to the identification of resistant clones have not used highly sensitive techniques (e.g. allelic discrimination to identify somatic mutations), coupled with the relatively low number of studies examining multiple molecular markers and the accepted molecular heterogeneity of NSCLC raise question as to the existence of 'acquired' versus 'de-novo' resistance. By examining the current knowledge base with respect to mechanisms of resistance to EGFR TKIs in NSCLC, we explore whether 'acquired' resistance is 'de-novo' resistance in disguise, and discuss the promises and limitations of molecular stratification with respect to strategies incorporating TKIs in the treatment of NSCLC.     

EGFR mutational status in penile cancer

Objective: No substantial improvement in overall survival has been obtained over the past two decades in penile cancer (PC). Clinical data are available on the role of epidermal growth factor receptors (EGFR) inhibitors in PC but no EGFR mutational analysis has been conducted.

Research design and methods: We reviewed formalin-fixed, paraffin-embedded blocks of PC at the Pathology Department of the National Cancer Institute since 2000 through 2012 to evaluate activating mutations in the tyrosine kinase domain of EGFR: EGFR E746 ? A750 specific deletion in exon 19 and EGFR L858R specific point mutation in exon 21.

Results: Thirty tumor samples were available for our analysis. EGFR was expressed in all samples at immunohistochemistry. Tested mutations were not identified in any of the samples analyzed.

Conclusions: The most frequent activating EGFR mutations detected in non-small setting lung cancer are absent in penile cancer (PC). Sequencing of the entire EGFR gene in patients with PC may provide useful insights, as its mechanism of overexpression and activation in PC remains unknown.     

T790M突变与表皮生长因子受体酪氨酸激酶抑制剂继发耐药的相关性

目的:探讨表皮生长因子本酪氨酸激酶抑制剂(EGFR-TKIs)治疗晚期非小细胞肺癌继发耐药的机制。方法:用富集突变PCR(Mutation–enriched PCR)分析46例初治有效且维持≥6个月的晚期非小细胞肺癌患者的外周血和石蜡包埋组织标本的EGFR20外显子T790M突变,分析其与病理特征、疗效、无疾病进展生存时间(PFS)的相关性。结果:46例患者进展期外周血标本中,T790M突变率为39.13%(18/46例),明显高于治疗前标本中5.88%(2/34例)。T790M突变阳性者中位PFS为16.4个月(95%CI:10.83～17.47),野生型患者中位PFS10.2个月(95%CI:10.2～13.47)(P=0.6139)。结论:研究表明T790M突变与EGFR-TKIs继发耐药相关,在非小细胞肺癌患者中存在动态变化,与疗效和生存可能有一定相关性。     

Detection of EGFR Somatic Mutations in Non-Small Cell Lung Cancer (NSCLC) Using a Novel Mutant-Enriched Liquidchip (MEL) Technology

We have developed and standardized a novel technology, mutant-enriched liquidchip (MEL), for clinical detection of EGFR mutations. The MEL integrates a mutant-enriched PCR procedure with liquidchip technology for detections of EGFR exon 19 deletions and L858R mutation on both formalin-fixed and paraffin-embedded (FFPE) slides and plasma samples from patients with non-small cell lung cancer (NSCLC). The detection sensitivity was 0.1% of mutant DNA in the presence of its wild-type DNA. The cross-reaction rate was lower than 5%. To evaluate the MEL platform, the EGFR mutation status of 59 patients with advanced NSCLC treated with EGFRTKIs (Tyrosine Kinase Inhibitors) were tested on their FFPE samples. EGFR exon 19 deletions and L858R were detected in 21 patients (21/59) and 76.2% (16/21) of them had partial response to the EGFR-TKIs, while by sequencing method, only 4 (4/59) mutations were detected. Plasma samples from 627 patients with various stages of NSCLC were examined with the MEL and 22% of EGFR exon 19 deletions and L858R were detected. Furthermore, in patients with advanced disease there are more mutations detected in plasma samples than in patients with less advanced disease. In conclusion, the MEL is a sensitive, stable, and robust technology for detecting EGFR DNA mutations from both FFPE and plasma samples from patients with NSCLC and is now routinely used for clinical diagnosis.     

QSAR of clinically important EGFR mutant L858R/T790M pyridinylimidazole inhibitors

EGFR is a well‐established therapeutic target of clinical relevance in cancer. However, acquisition of secondary mutation (T790M) makes first‐generation inhibitors ineffective. Therefore, to circumvent the problem of resistance, new T790M/L858R (TMLR) double mutant inhibitors are required. In this study, fragment‐based QSAR models (GQSAR) were generated for pyridinylimidazole derivatives having biological activity against TMLR mutants. The GQSAR model developed using partial least squares regression via stepwise forward–backward variable selection technique showed best results as judged using statistical parameters (r², q², and pred_r²). Additionally, applicability domain of the model was verified using Williams plot, which indicated that the predicted data are reliable. The GQSAR provided site‐specific clues wherein modifications related to decreasing lipophilic character and rotatable bonds and increasing SaaCHE‐index are required for improving inhibitory activity. Overall, the study indicated that the presence of acrylamide at R5 is essential for covalent bond formation with Cys797 and occurrence of aromatic residue at R2 is required for occupying hydrophobic region next to Met790 gatekeeper residue. Based on this information, new derivatives were designed that show better inhibitory activity than the experimentally reported most active molecules. Thus, the model developed can be used to design new pyridinylimidazole derivatives with improved TMLR bioactivity.     

Osimertinib for the treatment of non-small cell lung cancer

Introduction: The T790 M mutation of the epidermal growth factor receptor (EGFR) gene is the most common mechanism underlying resistance to first- or second-generation EGFR tyrosine kinase inhibitors (TKIs) in patients with non-small cell lung cancer (NSCLC). Osimertinib, a third-generation EGFR TKI, shows robust clinical efficacy in patients with T790 M-mutated lung cancer.

Areas covered: We analyzed and reviewed clinical data for which patients who experienced acquired resistance to first- or second-generation EGFR TKIs. In addition, we briefly reviewed the potential role of osimertinib as a first-line therapy.

Expert opinion: Osimertinib was recently licensed for use in NSCLC patients with acquired resistance to other EGFR TKIs due to a T790 M mutation. However, unresolved issues surrounding the optimal application of osimertinib remain, specifically the development of a plasma-based mutation test to overcome the difficulty of repeat biopsy, the efficacy of osimertinib for brain or leptomeningeal metastases, the development of resistance to osimertinib, and the use of osimertinib therapy as a first-line treatment. Many ongoing studies are currently exploring these issues.     

湖南地区238 例非小细胞肺癌EGFR 基因突变状态分析

目的：评价湖南地区非小细胞肺癌患者EGFR基因突变状态及其与临床特征之间的关系。方法收集2012年1月至2013年6月中南大学湘雅医学院附属肿瘤医院手术切除的非小细胞肺癌石蜡包埋组织238例,采用PCR扩增结合直接基因测序的方法,对组织DNA中EGFR基因第18-21外显子突变进行检测。结果在238例非小细胞肺癌中,EGFR突变的检出率为35.3％（84/238）。其中,第18、19、20、21号外显子突变占总突变的比例分别为2.4％（2/84）、67.9％（57/84）、3.6％（3/84）、26.2％（22/84）。19号外显子的突变均为第746-753密码子的碱基缺失,以Del E746-A750为主;21号外显子突变类型以L858R为主。女性EGFR基因的突变率显著高于男性,不吸烟者显著高于吸烟者（P〈0.05）。而EGFR基因的突变率与非小细胞肺癌患者的年龄、临床分期和淋巴结转移均无相关性（P〉0.05）。结论湖南地区的非小细胞肺癌EGFR基因突变以19、21外显子为主,且19外显子的突变率高于21外显子,多见于女性、腺癌、不吸烟患者。