EGFR inhibitors in lung cancer

Targeted therapies inhibiting the epidermal growth factor receptor (EGFR) have been introduced in the treatment of patients with advanced non-small-cell lung cancer (NSCLC). Many inhibitors of the EGFR have been developed, targeting either the extracellular receptor domain with antibodies or the intracellular tyrosine kinase binding domain with small molecules. The tyrosine kinase inhibitor (TKI) gefitinib (Iressa) was the first targeted drug to be registered for the treatment of NSCLC after failure of chemotherapy. Given concurrently together with platinum combination chemotherapy both TKIs gefitinib and erlotinib (Tarceva) failed to increase activity. Sequential targeted therapy after chemotherapy is currently being investigated further. Studies with the monoclonal antibody cetuximab (Erbitux) combined with chemotherapy are ongoing. Side effects of the small molecules are mainly skin rash and diarrhea, whereas the antibodies do not give diarrhea. Selection of patients, based on molecular markers and patient characteristics, has become an important issue for the further development of these drugs, given there is activity in a relatively small group of patients with NSCLC. Newer drugs inhibiting more than one receptor pathway are being investigated in order to find activity in a broader group of patients.     

晚期非小细胞肺癌一线靶向治疗的研究进展

肺癌是世界上发病率和死亡率最高的恶性肿瘤之一, 其中85%以上为非小细胞肺癌(non-small cell lung cancer, NSCLC)。目前, 对于复发或转移性晚期NSCLC, 化疗是必选治疗方法之一, 但其疗效已进入平台期, 近期和远期疗效均不甚理想。靶向治疗作为20世纪90年代以来的肿瘤研究重点, 在NSCLC的治疗中已占据重要地位。针对表皮生长因子受体的单克隆抗体(西妥昔单抗)和小分子酪氨酸激酶抑制剂(厄洛替尼尼或吉非替尼)、血管内皮生长因子的单克隆抗体(贝伐珠单抗)以及针对ALK阳性突变的抑制剂Crizotinib均已成为晚期NSCLC的一线治疗选择其中, 尤其以小分子酪氨酸激酶抑制剂疗效卓越, 在表皮生长因子受体突变的患者中, 其单药应用的疗效优于一线化疗, 有效率高达60%以上, 可使患者的无疾病进展时间延长至10个月。本文将就以上几种药物的相关临床研究对目前晚期NSCLC一线靶向治疗加以综述。      

Epidermal growth factor receptor tyrosine kinase inhibitors in elderly or poor performance status patients with advanced non-small cell lung cancer

Elderly and poor performance status advanced non-small cell lung cancer (NSCLC) patients often tolerate chemotherapy poorly. Special approaches are needed for these patient populations. Tyrosine kinase inhibitors (TKIs) of the epidermal growth factor receptor (EGFR), erlotinib and gefitinib, are active agents in the treatment of advanced NSCLC. Several phase II trials have been conducted utilizing EGFR TKIs in elderly or poor performance status patients with advanced NSCLC. This review will summarize the results of erlotinib or gefitinib in these subsets of patients with advanced NSCLC.     

Epidermal growth factor receptor mutations, small-molecule kinase inhibitors, and non-small-cell lung cancer: current knowledge and future directions.

PURPOSE: 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. DESIGN: 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. RESULTS: The discovery of EGFR mutations promises to alter the ways in which we consider and treat NSCLC. CONCLUSION: This information can guide practitioners and help them inform their patients about EGFR mutations and their impact on the treatment of NSCLC.     

Molekular zielgerichtete Therapie des nichtkleinzelligen Lungenkarzinoms

Chemotherapy remains the standard first-line treatment for advanced non-small cell lung cancer (NSCLC). In the second or third-line setting, however, the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor erlotinib has proven its benefit in a randomized trial. FDA approval of gefitinib was withdrawn after the negative results of the ISEL study. Recent identification of mutations in the ATP binding pocket of EGFR is the first step towards proper patient selection for therapy with gefitinib. Predictive potential for erlotinib application has been seen with EGFR gene amplification. Monoclonal antibodies against EGFR are evaluated in NSCLC. Use of the anti-angiogenic monoclonal VEGF antibody bevacizumab showed a survival benefit in a selected group of NSCLC patients in combination with standard chemotherapy in a phase III study. Confirmatory studies are awaited before the addition of bevacizumab to standard chemotherapy can be generally recommended. Multi-kinase inhibitors such as sorafenib show great promise for systemic treatment of solid cancers, including NSCLC.     

Gefitinib ('Iressa', ZD1839) and new epidermal growth factor receptor inhibitors

The epidermal growth factor receptor (EGFR) is a promising target for cancer therapy and a number of EGFR-targeted agents have been developed. Those most advanced in development are the EGFR tyrosine kinase inhibitors gefitinib ('Iressa', ZD1839) and erlotinib ('Tarceva', OSI-774), and the monoclonal antibody cetuximab ('Erbitux', IMC-C225). This review provides a clinical overview of these agents, highlighting their antitumour activities in different tumour types. Epidermal growth factor receptor-targeted agents are generally well tolerated and are not typically associated with the severe adverse events often seen with cytotoxic chemotherapy. Gefitinib is the agent with the most extensive clinical experience, particularly in non-small-cell lung cancer (NSCLC). Recently, gefitinib became the first-approved EGFR-targeted agent, for use in patients with previously treated advanced NSCLC in Japan, the USA and other countries. Further studies are required to explore the full potential of these novel agents either as monotherapy or combination therapy.     

Inhibitors of the EGFR pathway in non small cell lung cancer: what's new in 2007?

Non small cell lung cancer (NSCLC) is a major health public issue because of its frequency and related mortality. Progress with chemotherapy in advanced NSCLC has reached a plateau and more effective and better tolerated therapeutic strategies are needed. Epidermal growth factor receptor (EGFR) is overexpressed in 80% of NSCLC and inhibitors of EGFR tyrosine kinase have now an important place in the management of NSCLC. Most significant results have been obtained with oral inhibitors like erlotinib or gefitinib. Erlotinib role in second and third line setting is firmly established. Recent data suggests that in the first line setting, interesting overall response rates improving survivals can be obtained, in specific subpopulations defined either by histology (adenocarcinomas, adenocarcinomas with bronchioloalveolar features), sex (women), non-smoking status (never-smokers) or biological markers (tumours with EGFR mutations in exons 18-21). Such improvements are especially valuable because inhibitors of EGFR tyrosine kinase are better tolerated than chemotherapy. The exact contribution of monoclonal antibodies like cetuximab is still unclear in NSCLC.     

Current knowledge and future directions of the selective epidermal growth factor receptor inhibitors erlotinib (Tarceva) and gefitinib (Iressa)

Gefitinib (Iressa); AstraZeneca Pharmaceuticals, Wilmington, DE, http://www.astrazeneca-us.com) and erlotinib (Tarceva); OSI Pharmaceuticals, Inc., Melville, NY, http://www.osip.com) are so-called small molecules that selectively inhibit epidermal growth factor receptor (EGFR) tyrosine kinase activity. Both drugs received registration approval by the U.S. Food and Drug Administration (FDA) for the second- and third-line treatment of non-small cell lung cancer (NSCLC), but the failure of gefitinib to show a survival advantage over placebo has resulted in a discussion about the registration of gefitinib. Recently published results have revealed that mutations in the tyrosine kinase domain of EGFR are strongly associated with increased gefitinib and erlotinib sensitivity in patients with advanced NSCLC. Here, we present the current knowledge and the future directions of the EGFR tyrosine kinase inhibitors gefitinib and erlotinib.     

Bevacizumab and erlotinib: a promising new approach to the treatment of advanced NSCLC

Biologic agents that target molecules involved in tumor growth, progression, and pathological angiogenesis--such as the human epidermal growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF)--have demonstrated efficacy in patients with non-small cell lung cancer (NSCLC). Erlotinib (Tarceva); OSI Pharmaceuticals, Inc., Melville, NY, Genentech, Inc., South San Francisco, CA, and F. Hoffmann-La Roche Ltd, Basel, Switzerland), a highly selective tyrosine kinase inhibitor that inhibits EGFR, and bevacizumab (Avastin); Genentech, Inc., South San Francisco, CA, and F. Hoffmann-La Roche Ltd, Basel, Switzerland), a VEGF-targeted recombinant humanized monoclonal antibody, have displayed very encouraging activity in a randomized phase II trial in patients with previously treated NSCLC. Because erlotinib and bevacizumab act on two different pathways critical to tumor growth and dissemination, administering these drugs concomitantly may confer additional clinical benefits to cancer patients with advanced disease, by virtue of their complementary (or additive) antitumor activity. The combination of bevacizumab plus erlotinib may prove to be a viable second-line alternative to chemotherapy or erlotinib monotherapy in patients with NSCLC. The benefits of the combination may be further enhanced by selecting for patients who are likely to respond to this therapy. While a number of potential predictive markers have been identified for erlotinib, their value remains to be confirmed in prospective trials. In addition, the application of such personalized therapy will also depend on the availability of validated screening methods.     

Epidermal growth factor receptor inhibitors plus chemotherapy in non-small-cell lung cancer: biologic rationale for combination strategies

Chemotherapy continues to play an essential role in the treatment of most stages of non-small-cell lung cancer (NSCLC). In fact, within the past 5 years, this role has greatly expanded into adjuvant therapy for early-stage resected disease. Likewise, agents targeting the epidermal growth factor receptor (EGFR), particularly the tyrosine kinase inhibitors gefitinib and erlotinib, have proven to be clinically active in patients with advanced-stage NSCLC. Because of these findings, it is logical to expect that combinations of these 2 classes of antineoplastic agents would prove more efficacious than either one alone. Yet 4 large randomized phase III trials of chemotherapy with or without an EGFR tyrosine kinase inhibitor in unselected patients with advanced-stage NSCLC, altogether totaling > 4000 patients, did not demonstrate improvement in clinical outcomes with the combination. Whether these negative results will be reproduced in ongoing combination studies of chemotherapy plus monoclonal antibodies directed against EGFR remain to be determined. Herein, we review recent preclinical and clinical data addressing this topic and explore the biologic rationale for developing new combination strategies based on patient selection by molecular and clinical factors, or by pharmacodynamic parameters.     

Targeting epidermal growth factor receptor in lung cancer: Perspective from the Asia–Pacific region

The epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase of the ErbB family that is frequently overexpressed in non‐small cell lung cancer (NSCLC), and has been identified as a novel therapeutic target for lung cancer. The development of small molecule EGFR‐tyrosine kinase inhibitors (TKI) such as gefitinib and erlotinib has resulted in paradigm shift in the treatment of advanced NSCLC. The impact of EGFR‐TKI in the treatment of NSCLC is even greater in Asia–Pacific region because one of the greatest clinical benefits of EGFR‐TKI has been seen in patients of East Asian ethnicity. The discovery of somatic mutations in EGFR‐tyrosine kinase domain has so far answered some, but not all, of the questions regarding the clinical response to EGFR‐TKI in NSCLC. In addition, other molecular profiles such as KRAS mutations have also been found to play an important role in EGFR targeted therapy. In this article, we review EGFR targeted therapy in NSCLC with the focus on perspective from the Asia–Pacific region.     

Erlotinib in non-small cell lung cancer treatment: current status and future development

Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related mortality worldwide. Standard treatment approaches such as chemotherapy, radiotherapy, and surgery have reached a plateau in this disease. Therefore, alternatives to conventional treatment, such as new molecular-targeted therapies, are needed. Targeting the epidermal growth factor receptor (EGFR) has played a central role in advancing NSCLC research, treatment, and patient outcome over the last several years. There are two EGFR tyrosine kinase inhibitors approved for the treatment of advanced NSCLC: gefitinib and erlotinib. Of these, erlotinib has shown a significant improvement in median survival, quality of life, and related symptoms in an unselected population of advanced and metastatic NSCLC patients in the second- or third-line setting. Furthermore, erlotinib has significant antitumor activity in first-line treatment. Moreover, factors that predict the efficacy of erlotinib, including clinical, pathologic, and molecular features, have been investigated. A series of studies is planned to contribute to our understanding of the role of erlotinib in NSCLC treatment. Major areas of clinical research are the assessment of erlotinib: in adjuvant treatment, combined with chemotherapy and/or radiotherapy in locally advanced disease, in the first-line therapy of advanced disease, and in combination and/or sequence with cytotoxic treatments and/or other molecular target agents.     

The use of first-generation tyrosine kinase inhibitors in patients with NSCLC and somatic EGFR mutations

Initial studies with the first-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors gefitinib and erlotinib in patients with non-small cell lung cancer (NSCLC) showed that, although most did not have an objective radiographic response, a minority of patients had dramatic and durable clinical and radiographic responses. The discovery of EGFR mutations in tumours from patients with NSCLC and the association of these mutations with clinical response to gefitinib and erlotinib provided an opportunity to tailor treatment to the mutation profile of the tumour. A number of retrospective reviews and prospective trials have established that gefitinib or erlotinib therapy leads to radiographic responses in approximately 75-80% of patients with NSCLC with EGFR mutations. Although a variety of mutations in EGFR have been identified, the two most common somatic activating EGFR mutations are the LREA deletions in exon 19 and the L858R substitution in exon 21. Together, these mutations make up 85-90% of EGFR mutations. At least two retrospective reviews have indicated a difference in the outcome of patients with different EGFR mutations: after treatment with gefitinib or erlotinib, patients with exon 19 deletions have an increased survival compared with those patients whose tumours have an L858R substitution. These findings remain to be confirmed in prospective studies. Improved understanding of the association of EGFR mutations with clinical outcome may improve the ability of physicians to match treatment to mutation status for patients with NSCLC.     

EGFR-TKI治疗非小细胞肺癌研究进展

吉非替尼和厄洛替尼均为小分子量表皮生长因子受体酪氨酸激酶抑制剂(EGFR-TKI),已在化疗失败的晚期非小细胞肺癌(NSCLC)解救治疗中取得疗效,但仅对特定人群发挥作用。EGFR- TKI联合化疗一线治疗NSCLC并未能提高疗效;正在进行的临床研究聚焦于优势人群EGFR-TKI一线治疗或联合化疗的研究。     

Overview of the current status of human epidermal growth factor receptor inhibitors in lung cancer

Although chemotherapy remains the standard of care for lung cancer, new less toxic drugs are urgently needed. Targeted agents represent a new era in cancer therapy, and non-small-cell lung cancer (NSCLC) is at the forefront of many development programs. An exciting target is the human epidermal growth factor receptor (EGFR, ie, HER1), and agents targeting this receptor, including gefitinib, cetuximab, and erlotinib (OSI-774; Tarceva), are being investigated. These agents have antitumor activity and are less toxic than most therapies. Based on phase II data, gefitinib received US approval for third-line treatment of patients with locally advanced or metastatic NSCLC. Cetuximab is licensed in the United States for patients with metastatic colorectal carcinoma. However, erlotinib, recently approved in the United States for second- and third-line treatment of patients with locally advanced or metastatic NSCLC, is the only agent of this class to improve survival as monotherapy in patients with advanced, refractory NSCLC, as shown in a phase III placebo-controlled trial. Phase III trials of erlotinib and gefitinib combined with chemotherapy were disappointing, which could be the result of drug scheduling, chemotherapy combinations, or other factors. Patient characteristics may also affect outcome, and research is ongoing to identify predictive markers of response to enable patient selection and improve outcome. Recently identified mutations within the HER1/EGFR tyrosine kinase (TK) domain may provide insight into why some patients respond rapidly to HER1/EGFR tyrosine kinase inhibitors. Surrogate markers of efficacy are also being investigated, including rash, which could be used to monitor and optimize antitumor activity. Therefore, although more work is required, data indicate that HER1/EGFR inhibitors will play an important role in treating patients with NSCLC.     

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.     

EGFR-mutated oncogene-addicted non-small cell lung cancer: current trends and future prospects

Non-small cell lung cancer (NSCLC) tumours with certain mutations in the epidermal growth factor receptor (EGFR) tyrosine kinase have been termed 'oncogene addicted' to reflect their dependence on EGFR-mediated pro-survival signalling and their high susceptibility to apoptosis induced by EGFR tyrosine kinase inhibitors (EGFR-TKIs, e.g. gefitinib and erlotinib). The most common mutations (L858R and exon 19 deletions) predict an improved clinical response to first-line oral EGFR-TKIs compared with standard platinum-based chemotherapy in patients with advanced NSCLC. Moreover, these mutations are also prognostic of a relatively indolent course of disease, regardless of treatment, as compared with classical NSCLC. Treatment strategies for oncogene-addicted NSCLC are therefore distinct from those for non-oncogene addicted NSCLC, and will depend on the specific genetic mutation present.     

Epidermal growth factor receptor inhibitors and their role in non-small-cell lung cancer

The epidermal growth factor receptor (EGFR) is a promising target in the treatment of advanced stage non-small-cell lung cancer (NSCLC). Currently erlotinib and gefitinib are approved by the US Food and Drug Administration, whereas cetuximab is being studied for use in NSCLC. Erlotinib has shown a survival advantage in patients with advanced NSCLC. Further studies have identified female sex, nonsmokers, Asian race, good performance status, and adenocarcinoma histology as predictors of patient response to these agents. A genetic mutation in EGFR has also been correlated with an increase in response.     

Preface

Non-small cell lung cancer (NSCLC) is the major cause of cancer-related deaths in the USA and worldwide. Most patients present with advanced disease, and treatment options for these patients are generally limited to platinum-based chemotherapy and a few targeted therapies. Targeted agents currently in use for NSCLC inhibit oncogenic receptor tyrosine kinase pathways, such as the epidermal growth factor receptor (EGFR) pathway. While current EGFR-targeted agents, including erlotinib and gefitinib, may result in dramatic responses, they demonstrate efficacy in only a fraction of patients, and resistance to these agents frequently develops. In order to select patients most likely to benefit from blockade of EGFR pathways, investigators have focused on identifying molecular correlates of response to anti-EGFR therapy. New strategies to minimize the risk of resistance to EGFR inhibition have been employed in the development of next-generation EGFR tyrosine kinase inhibitors, such as PF00299804 and BIBW 2992; these include irreversibility of target binding, inhibition of multiple EGFR family receptors, and/or simultaneous inhibition of EGFR and other oncogenic pathways.