EGFR基因靶向治疗非小细胞肺癌的研究进展

非小细胞肺癌(Non-small cell lung cancer,NSCLC)是现阶段临床发现的肺癌患者中发病率最高的一种类型,治疗手段匮乏,效果不甚理想,目前临床中研究热点是EGFR基因在NSCLC靶向治疗中的作用。表皮生长因子受体酪氨酸激酶抑制剂(EGFR-TKIs)是基于EGFR基因作用而开发出来,用于治疗EGFR基因突变阳性的NSCLC患者。本文综述了EGFR基因靶向治疗非小细胞肺癌的研究进展。     

The epidermal growth factor receptor gene family as a target for therapeutic intervention in numerous cancers: what's genetics got to do with it?

Over the past 30 years, a relatively simple growth factor and its cognate receptor have provided seminal insights into the understanding of the genetic basis of cancer, as well as growth factor signalling. The epidermal growth factor (EGF), its cognate receptor (EGFR) and related family members have been shown to be important in normal, as well as the malignant growth of many cell types including: glioblastomata, astrocytomas, medulloblastomata, non-small cell lung carcinoma (NSCLC) and breast cancer. This review summarises the history of the EGFR gene and the v-ErbB oncogene, as well as diverse approaches developed to inhibit EGFR activity. The two most advanced therapies use either small-molecule cell membrane permeable kinase inhibitors or antibodies which prevent receptor activation. Recent clinical trials indicate that certain NSCLC patients have mutations in the EGFR gene which makes them more responsive to kinase inhibitors. These mutations appear to enhance the ability of the ligand to activate EGFR activity and also prolong the binding of the EGFR inhibitor to the kinase domain. Evidence to date suggests that these EGFR mutations in NSCLC occur more frequently in Japan than in the western hemisphere. Although these mutations are correlated with enhanced efficacy to the inhibitors in NSCLC, they can not explain or predict the sensitivity of many other cancer patients to the beneficial effects of the EGFR kinase inhibitors or antibody mediated therapy. As with as other small-molecule kinase inhibitors and susceptible diseases (e.g., imatinib and chronic myeloid leukaemia), resistance to EGFR inhibitors has been reported recently, documenting the requirement for development of multi-pronged therapeutic approaches. EGFR kinase inhibitors are also being evaluated as adjuvants in hormonal therapy of breast cancer - especially those which overexpress EGFR. Genetically engineered antibodies specific for the EGFR family member ErbB2 have been developed which show efficacy in the treatment of primary, and prevent the relapse of, breast cancer. Clearly, the EGF/EGFR signalling cascade has, and continues to play, an important role in the development of novel anticancer targeted therapies.     

The epidermal growth factor receptor gene family as a target for therapeutic intervention in numerous cancers: what’s genetics got to do with it?

Over the past 30 years, a relatively simple growth factor and its cognate receptor have provided seminal insights into the understanding of the genetic basis of cancer, as well as growth factor signalling. The epidermal growth factor (EGF), its cognate receptor (EGFR) and related family members have been shown to be important in normal, as well as the malignant growth of many cell types including: glioblastomata, astrocytomas, medulloblastomata, non-small cell lung carcinoma (NSCLC) and breast cancer. This review summarises the history of the EGFR gene and the v-ErbB oncogene, as well as diverse approaches developed to inhibit EGFR activity. The two most advanced therapies use either small-molecule cell membrane permeable kinase inhibitors or antibodies which prevent receptor activation. Recent clinical trials indicate that certain NSCLC patients have mutations in the EGFR gene which makes them more responsive to kinase inhibitors. These mutations appear to enhance the ability of the ligand to activate EGFR activity and also prolong the binding of the EGFR inhibitor to the kinase domain. Evidence to date suggests that these EGFR mutations in NSCLC occur more frequently in Japan than in the western hemisphere. Although these mutations are correlated with enhanced efficacy to the inhibitors in NSCLC, they can not explain or predict the sensitivity of many other cancer patients to the beneficial effects of the EGFR kinase inhibitors or antibody mediated therapy. As with as other small-molecule kinase inhibitors and susceptible diseases (e.g., imatinib and chronic myeloid leukaemia), resistance to EGFR inhibitors has been reported recently, documenting the requirement for development of multi-pronged therapeutic approaches. EGFR kinase inhibitors are also being evaluated as adjuvants in hormonal therapy of breast cancer – especially those which overexpress EGFR. Genetically engineered antibodies specific for the EGFR family member ErbB2 have been developed which show efficacy in the treatment of primary, and prevent the relapse of, breast cancer. Clearly, the EGF/EGFR signalling cascade has, and continues to play, an important role in the development of novel anticancer targeted therapies.     

Pharmacotherapy targeting the EGFR oncogene in NSCLC

Introduction: The EGFR plays a central role in regulating cancer cell growth and survival, representing an attractive therapeutic target in NSCLC.

Areas covered: For the purpose of this review article, data from Phase II and III trials with anti-EGFR agents, including EGFR-tyrosine kinase inhibitors (TKIs) and mAbs, were collected and analysed.

Expert opinion: Eight large Phase III trials demonstrated that EGFR-TKIs are the best option we can offer today as front-line therapy exclusively in EGFR mutant NSCLC. In patients with EGFR wild type or unknown lung cancer, platinum-based chemotherapy remains the standard of care, with no consistent benefit produced by the addition of an anti-EGFR treatment. In pretreated NSCLC, EGFR-TKIs are considered more effective than standard monotherapy with cytotoxics in presence of classical EGFR mutations, whereas in the EGFR wild-type population, a similar efficacy with docetaxel or pemetrexed in terms of survival has been demonstrated. New agents targeting EGFR are under investigation, particularly in individuals with squamous cell histology and those with acquired resistance to EGFR-TKIs.     

Targeting epidermal growth factor receptor in the treatment of non-small-cell lung cancer

Importance of the field: The management of non-small-cell lung cancer (NSCLC) has undergone a paradigm shift in the last decade, with the survival advantage demonstrated by the incorporation of anti-epidermal growth factor receptor (EGFR) agents to the standard treatment of advanced/metastatic NSCLC.

Areas covered in this review: We review the existing data regarding the distinct anti-EGFR agents in the NSCLC treatment and the potential role of the investigated biomarkers in the clinical outcome.

What the reader will gain: Tyrosine kinase inhibitors have been used in first-line, second-line and more settings with extremely good results in a subgroup of patients. Cetuximab remains the only anti-EGFR monoclonal antibody to show survival benefit when combined with a cytotoxic agent in the front-line setting. Anti-EGFR treatment is associated with a dramatic clinical benefit in a subgroup of patients, emphasizing the importance of customizing treatment. Several biomarkers have been investigated for their predictive or prognostic value. Validation of identification of biomarkers remains a focus of intense research that may ultimately guide therapeutic decision making, as none of these is considered ideal to discriminate responding from non-responding patients. However, the current evidence of the EGFR mutation analysis from a recent randomised trial suggests that EGFR mutation analysis is quite a good predictive marker for responsiveness to anti-EGFR TKIs. Moreover, the identification of surrogate markers to indicate optimal activity of the anti-EGFR agent is also needed. This review article provides data from large clinical trials using anti-EGFR agents and correlates these results with the tested biomarkers.

Take home message: EGFR inhibition has shown very encouraging results and has improved the outcome of the NSCLC treatment. However, a plateau of significant clinical benefit seems to have been reached and we believe that the time to move away from the traditional treatment approach to more individualizing therapies has come.     

非小细胞肺癌EGFR基因突变阳性的临床意义

目的：探讨非小细胞肺癌表皮生长因子受体（EGFR）第19、21号外显子突变与其临床病理特征、家族史的关系,以及对突变阳性患者使用表皮生长因子受体酪氨酸激酶抑制剂（EGFR-TKIs）靶向治疗的效果。方法采用扩增阻滞突变系统聚合酶链反应技术对EGFR第19、21号外显子进行检测。结果162例非小细胞肺癌患者发生EGFR突变阳性63例,突变阳性率为38.89%。腺癌、女性、非吸烟者、有肺癌及其他恶性肿瘤家族史的非小细胞肺癌患者EGFR突变率明显升高,差异有统计学意义（P0.05）。非小细胞肺癌发生EGFR突变阳性使用EGFR-TKIs靶向治疗患者的中位生存期明显长于未治疗及其他药物化疗患者,差异有统计学意义（P〈0.01）。结论非小细胞肺癌患者EGFR突变筛查应作为常规临床检测指标,特别是对于有肿瘤家族史患者更具有临床意义。     

Optimal management of patients with non-small cell lung cancer and epidermal growth factor receptor mutations

In recent years, the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs), gefitinib and erlotinib, which have promising activity and a favourable toxicity profile, have been used in the management of advanced non-small cell lung cancer (NSCLC). The knowledge that EGFR-activating mutations confer sensitivity to EGFR TKIs has led to the design and analysis of phase II and III studies of gefitinib or erlotinib treatment in various clinical scenarios. We review the important NSCLC clinical trials of the efficacy of EGFR TKIs in the context of EGFR-activating mutations. In all phase II single-arm studies or phase III randomized comparative studies, EGFR TKIs as monotherapy were superior to combination chemotherapy in terms of response rate and progression-free survival in patients with activating EGFR mutations. EGFR TKIs have contributed to the superior overall survival time in NSCLC patients with EGFR mutations compared with those patients without EGFR mutations. The results of these studies have led to a paradigm shift in the treatment of patients with advanced NSCLC. NSCLC with EGFR mutations constitutes a new entity requiring different personalized treatment strategies.     

Review. EGFR mutations in non-small cell lung cancer--clinical implications

The epidermal growth factor receptor (EGFR) family members seem to play a critical role in lung tumourigenesis and are overexpressed in 40-80% of non-small cell lung carcinoma (NSCLC) tumours. EGFR activation results in a series of downstream signaling events that mediate cancer cell growth, proliferation, motility, adhesion, invasion, apoptosis inhibition and metastasis as well as resistance to chemotherapy. Therefore, EGFR inhibitors seem to be an effective therapy for some patients with previously treated NSCLC. A thorough investigation of EGFR, its major signaling pathways, its identification and biology in NSCLC and the responsiveness to gefitinib, erlotinib and cetuximab in connection to EGFR mutations as well as the possible mechanisms of resistance to tyrosine kinase inhibitors is the scope of this review.     

Epidermal growth factor receptor inhibitors in the treatment of non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related death in both men and women. Despite the introduction of the newer cytotoxic agents in NSCLC treatment during the last decade the survival rates of patients have reached a plateau. New strategies are clearly needed to improve treatment outcomes. Epidermal growth factor receptor (EGFR) has a key role in cancer development and progression and has been recognised as a target of increasing importance in NSCLC. Gefitinib, erlotinib and cetuximab are EGFR-targeting agents that are being extensively evaluated in NSCLC. EGFR inhibitors demonstrate significant clinical activity in approximately 10-20% of pretreated NSCLC patients. Somatic mutations in the kinase domain of the receptor have been shown to be associated with enhanced sensitivity to EGFR inhibitors. However, four large Phase III randomised, placebo-controlled trials of gefitinib and erlotinib in combination with standard platinum-based first-line chemotherapy failed to show any survival benefit in patients receiving the study drugs. Possible reasons include patient selection, drug scheduling, trial design or other factors. Active research is ongoing to improve the efficacy of EGFR inhibitors as monotherapy or in combination with other treatment modalities.     

Epidermal growth factor receptor inhibitors in the treatment of non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related death in both men and women. Despite the introduction of the newer cytotoxic agents in NSCLC treatment during the last decade the survival rates of patients have reached a plateau. New strategies are clearly needed to improve treatment outcomes. Epidermal growth factor receptor (EGFR) has a key role in cancer development and progression and has been recognised as a target of increasing importance in NSCLC. Gefitinib, erlotinib and cetuximab are EGFR-targeting agents that are being extensively evaluated in NSCLC. EGFR inhibitors demonstrate significant clinical activity in ~ 10 – 20% of pretreated NSCLC patients. Somatic mutations in the kinase domain of the receptor have been shown to be associated with enhanced sensitivity to EGFR inhibitors. However, four large Phase III randomised, placebo-controlled trials of gefitinib and erlotinib in combination with standard platinum-based first-line chemotherapy failed to show any survival benefit in patients receiving the study drugs. Possible reasons include patient selection, drug scheduling, trial design or other factors. Active research is ongoing to improve the efficacy of EGFR inhibitors as monotherapy or in combination with other treatment modalities.     

CT引导下非小细胞肺癌穿刺标本检测表皮生长因子受体基因突变的临床应用

目的：探讨螺旋CT引导下经皮肺穿刺活检获得标本组织检测非小细胞肺癌（NSCLC）表皮生长因子受体（EGFR）基因突变的临床价值。方法：入组38例晚期或局部晚期无法手术的NSCLC患者,采用18G自动活检枪,经CT引导行皮肺穿刺活检获取肿瘤组织,行组织学诊断及EGFR基因检测,观察术后并发症,分析检测结果。结果：38例病例经穿刺活检均获得理想的病理标本进行组织学诊断和基因突变检测,其中腺癌患者突变率与非腺癌患者突变率差异有统计学意义;女性患者突变率与男性患者突变率差异亦有统计学意义;未发生严重并发症;EGFR基因突变患者使用吉非替尼治疗获得较好疗效。结论：CT引导的经皮肺穿刺活检技术安全有效,是晚期NSCLC获得肿瘤组织检测EGFR基因突变的可靠方法,可为临床药物分子靶向治疗提供依据。     

Recent understanding of the molecular mechanisms for the efficacy and resistance of EGF receptor-specific tyrosine kinase inhibitors in non-small cell lung cancer

INTRODUCTION: The epidermal growth factor receptor (EGFR) and its family members are involved in many aspects of tumor biological processes. Aberrant activation of the EGFR tyrosine kinase by mutations or protein overexpression is observed in various types of human cancer, including lung cancer. EGFR tyrosine kinase inhibitors (EGFR-TKIs), such as gefitinib and erlotinib, are highly effective in lung cancer patients who harbor active mutations in the EGFR gene. However, patients who are initially sensitive to EGFR-TKIs eventually relapse within few years. AREAS COVERED: Non-small cell lung cancer (NSCLC) is the most common type of lung cancer and is associated with a high frequency of EGFR mutations. This review describes the EGFR mutations that determine the sensitivity to EGFR-TKIs and the current understanding of the molecular mechanisms of acquired resistance to EGFR-TKIs in NSCLC. Furthermore, the authors describe recent strategies developed to overcome acquired resistance using second-generation EGFR-TKIs and combination therapies with several molecular-targeting drugs. EXPERT OPINION: Although recent findings have contributed to our understanding of the mechanism of acquired resistance and helped the development of novel strategies to overcome such resistance, the underlying mechanisms are complex and additional research is necessary to develop effective therapeutic strategies for individual patients with lung cancer.     

Meta-analysis of the incidence and risk of arterial and venous thromboembolic events associated with anti-EGFR agents in non-small-cell lung cancer patients

Background: To determine the risk of arterial and venous thromboembolic events (ATEs and VETs) associated with anti-epidermal growth factor receptor (EGFR) agents in non-small-cell lung cancer (NSCLC) patients.

Methods: Prospective randomized trials evaluating therapy with or without anti-EGFR agents in NSCLC patients. Data on VTEs and ATEs were extracted.

Results: A total of 8,410 patients from 12 trials were included for analysis. Anti-EGFR agents significantly increased the risk of all-grade and high-grade VTEs (Peto OR 1.50, 95%CI 1.16–1.95, P = 0.002; Peto OR 1.73, 95%CI: 1.32–2.26, p < 0.001, respectively), but not for all-grade and high-grade ATEs.

Conclusion: The use of anti-EGFR agents significantly increased the risk of all-grade and high-grade VTEs but not for ATEs in NSCLC patients.     

厄洛替尼单药一线治疗非小细胞肺癌的研究进展

高效低毒的分子靶向治疗药物厄洛替尼,在非小细胞肺癌(NSCLC)的二、三线治疗以及序贯和维持治疗中,已经显示出其能够使患者临床获益.厄洛替尼单药为晚期NSCLC的一线治疗新的选择方案.本文就其在老年、体力状态较差、不吸烟以及存在表皮生长因子(EGFR)敏感性突变或K-ras耐药突变的NSCLC患者中的应用作一综述.     

Recent advances in targeted therapy for non-small cell lung cancer

Non-small-cell lung cancer (NSCLC) is characterized by wide molecular heterogeneity. In recent years, novel agents that target specific, aberrant molecular pathways in NSCLC have been under rigorous evaluation. Erlotinib, an inhibitor of the epidermal growth factor receptor (EGFR) tyrosine kinase, improves survival for advanced NSCLC patients who progressed following one or two prior chemotherapy regimens. Novel molecular predictive markers, such as EGFR mutations and gene amplification, are at present under evaluation to select patients for therapy with erlotinib. Another area of progress is the recent demonstration that bevacizumab, a monoclonal antibody against the vascular endothelial growth factor (VEGF), extended survival when administered in combination with chemotherapy for patients with non-squamous NSCLC. Promising anticancer activity has also been noted with agents that inhibit the VEGF receptor tyrosine kinase in patients with advanced NSCLC. Inhibitors of the proteosomal complex, histone deacetylase, mammalian target of rapamycin pathway, and other growth factor receptor-mediated signaling are under investigation for treatment of NSCLC. These developments have paved the way for a new era of tailor-made therapies based on clinical or molecular/genetic profiles in the treatment of NSCLC. This article reviews the recent advances in targeted therapy of advanced NSCLC.     

Recent advances in targeted therapy for non-small cell lung cancer

Non-small-cell lung cancer (NSCLC) is characterized by wide molecular heterogeneity. In recent years, novel agents that target specific, aberrant molecular pathways in NSCLC have been under rigorous evaluation. Erlotinib, an inhibitor of the epidermal growth factor receptor (EGFR) tyrosine kinase, improves survival for advanced NSCLC patients who progressed following one or two prior chemotherapy regimens. Novel molecular predictive markers, such as EGFR mutations and gene amplification, are at present under evaluation to select patients for therapy with erlotinib. Another area of progress is the recent demonstration that bevacizumab, a monoclonal antibody against the vascular endothelial growth factor (VEGF), extended survival when administered in combination with chemotherapy for patients with non-squamous NSCLC. Promising anticancer activity has also been noted with agents that inhibit the VEGF receptor tyrosine kinase in patients with advanced NSCLC. Inhibitors of the proteosomal complex, histone deacetylase, mammalian target of rapamycin pathway, and other growth factor receptor-mediated signaling are under investigation for treatment of NSCLC. These developments have paved the way for a new era of tailor-made therapies based on clinical or molecular/genetic profiles in the treatment of NSCLC. This article reviews the recent advances in targeted therapy of advanced NSCLC.     

The fibroblast growth factor receptor signaling pathway as a mediator of intrinsic resistance to EGFR-specific tyrosine kinase inhibitors in non-small cell lung cancer

The EGFR has been targeted through the development of selective tyrosine kinase inhibitors (TKIs) that have proven effective in a subset of non-small cell lung cancer (NSCLC) patients, many bearing gain-of-function EGFR mutations or egfr gene amplification. However, the majority (～80–90%) of NSCLC patients do not respond to EGFR-specific TKIs and a high rate of acquired resistance to these therapeutics is observed in those that do respond. Thus, EGFR-specific TKIs will not, as single agents, make a high impact on overall lung cancer survival. A number of studies support the activities of other receptor tyrosine kinase pathways including cMet, IGF-1R and FGFRs as mechanisms for both intrinsic and acquired resistance to EGFR TKIs. While the role of cMet and IGF-1R signaling systems as mechanisms of resistance to EGFR TKIs has been widely reviewed in recent years, the potential role of FGFR-dependent signaling as a mechanism for EGFR TKI resistance has more recently emerged and will be highlighted herein. Due to the high degree of homology of FGFRs with VEGFRs and PDGFRs, FGFR-active TKIs already exist via development of VEGFR-targeted TKIs as angiogenesis inhibitors. Thus, these agents could be rapidly advanced into clinical investigations as FGFR inhibitors, either alone or in combination with TKIs selective for EGFR, cMet or IGF-1R as a means to expand the spectrum of NSCLC patients that can be effectively targeted with TKI-directed therapies.     

Sanger法检测分析非小细胞肺癌患者组织EGFR

目的探讨Sanger法检测非小细胞肺癌（non-small cell lung cancer,NSCLC）患者组织表皮生长因子受体（epidermal growth factor receptor,EGFR）基因突变情况,为肺癌病人“个体化靶向分子治疗”提供依据。方法收集63例NSCLC患者组织标本（石蜡切片）,提取组织DNA,用EGFR外显子18、19、20和21四位点的分子扩增（PCR）试剂盒进行外显子扩增,扩增产物先后进行电泳鉴定、酶解,酶解产物PCR扩增、纯化,纯化产物用ABI-3130型基因分析仪检测得出EGFR外显子18、19、20、21的野生或突变状态结果,并分析EGFR基因突变和患者临床病理生理特征、临床靶向用药疗效的关系。结果测试显示肺腺癌患者EGFR基因19、21外显子的突变率为33．3％（21／63）,而EGFR基因的突变与患者的病理组织学类型、吸烟状态有关（P〈0．05）。同时EGFR突变患者能从临床靶向用药获益。结论Sanger法检测NSCLC突变情况可为临床靶向用药提供技术支持。     

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.     

Anti-EGFR strategies as an incremental step for the treatment of colorectal cancer patients: moving from scientific evidence to clinical practice

The epidermal growth factor receptor (EGFR) is a 170,000 Da transmembrane glycoprotein involved in signalling pathways affecting cellular growth, differentiation and proliferation. An abnormal overexpression of the EGFR has been described in many human tumours and implicated in the development and prognosis of malignancies, thus representing not only a possible prognostic marker, but primarily a rational molecular target for a new class of anticancer agents. Several clinical trials have been reported with the use of EGFR-targeted monoclonal antibodies and tyrosine kinase inhibitors, mainly in combination with chemotherapy for advanced colorectal cancer patients. Taken together, results available so far suggest that anti-EGFR treatment strategies represent an incremental step for the the treatment of colorectal cencer patients with a manageable and acceptable toxicity profile. Nevertheless, many critical issues are yet unresolved, such as the optimal chemotherapy regimen to combine with anti-EGFR treatment and the most adequate patients setting. Moreover, the biological selection of colorectal tumours most likely to benefit from this treatment approach is still to be defined.