Gefitinib for non-small-cell lung cancer patients with epidermal growth factor receptor gene mutations screened by peptide nucleic acid-locked nucleic acid PCR clamp

Resistance to Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitors in Non-Small Cell Lung Cancer

Gefitinib and erlotinib are ATP competitive inhibitors of the epidermal growth factor receptor (EGFR) tyrosine kinase and are approved around the world for the treatment of patients with non-small cell lung cancer (NSCLC). Somatic mutations in the EGFR are found in 10 to 40% of patients with NSCLC. Patients with sensitizing somatic mutations of EGFR treated with gefitinib or erlotinib have an initial clinical response of 60 to 80%, approximately twice as high as the responses associated with the administration of conventional platinum-based chemotherapy. However, the efficacy of EGFR tyrosine kinase inhibitors (TKI) is limited by either primary (de novo) or acquired resistance after therapy and investigations to define the mechanisms of resistance are active areas of ongoing preclinical and clinical studies. Primary resistance is typically caused by other somatic mutations in genes such as KRAS, which also have an impact on the EGFR signaling pathway or by mutations in the EGFR gene that are not associated with sensitivity to EGFR-TKIs. Two established mechanisms of acquired resistance are caused by additional mutations in the EGFR gene acquired during the course of treatment that change the protein-coding sequence or by amplification of another oncogene signaling pathway driven by the MET oncogene. This review focuses on characterized mechanisms of resistance to the EGFR TKIs and efforts to overcome the problem of resistance aimed at improving the therapy of patients with NSCLC. (Clin Cancer Res 2009;15(24):7502-9).

A phase I/II trial of gefitinib given concurrently with radiotherapy in patients with nonmetastatic prostate cancer

PURPOSE

To estimate the safety and tolerability of daily administration of 250 mg of gefitinib given concurrently with three-dimensional conformal radiotherapy for patients with nonmetastatic prostate cancer.

METHODS AND MATERIALS

A total of 42 patients with T2-T3N0M0 tumors were treated in a nonrandomized single-center study. A prostate-specific antigen (PSA) level of <20 and a good performance status (WHO, 0-1) were required. Adjuvant or neoadjuvant hormone treatments were not allowed. A daily regimen of 250 mg of gefitinib was started 1 week before radiation therapy began and lasted for the duration of radiation therapy. A dose of 50.4 Gy (1.8 Gy/day) was administered to the tumor, prostate, and seminal vesicles, followed by a 22-Gy booster (2 Gy/day) for a total dose of 72.4 Gy. Correlative studies included analysis of epidermal growth factor receptor (EGFR), EGFRvIII, and phosphorylated EGFR in tumors and tumor necrosis factor, interleukin-1alpha (IL-1alpha), and IL-6 in serum.

RESULTS

Maximum tolerated dose was not reached in phase I (12 patients), and 30 additional patients were treated in phase II. Thirty (71.4%) patients completed trial medication. Dose-limiting toxicities were recorded for 16 (38.1%) patients, the most common of which was a grade 3 to 4 increase in transaminase (6 patients). After a median follow-up of 38 months, there were no deaths due to prostate cancer. The estimated PSA relapse-free survival rate at 4 years (Kaplan-Meier) was 97%, the salvage therapy-free survival rate was 91%, and the overall survival rate was 87%. These figures compared favorably with those of matched patients treated with radiation only at higher doses.

CONCLUSIONS

The combination of gefitinib and radiation is reasonably well tolerated and has promising activity against nonmetastatic prostate cancer.

Epidermal growth factor receptor in relation to tumor development: EGFR-targeted anticancer therapy

The discovery that signaling by the epidermal growth factor receptor (EGFR) plays a key role in tumorigenesis prompted efforts to target this receptor in anticancer therapy. Two different types of EGFR-targeted therapeutic agents were subsequently developed: mAbs, such as cetuximab and panitumumab, which target the extracellular domain of the receptor, thereby inhibiting ligand-dependent EGFR signal transduction; and small-molecule tyrosine kinase inhibitors, such as gefitinib and erlotinib, which target the intracellular tyrosine kinase domain of the EGFR. Furthermore, recent clinical and laboratory studies have identified molecular markers that have the potential to improve the clinical effectiveness of EGFR-targeted therapies. This minireview summarizes the emerging role of molecular profiling in guiding the clinical use of anti-EGFR therapeutic agents.

American Society of Clinical Oncology Clinical Practice Guideline update on chemotherapy for stage IV non-small-cell lung cancer

The purpose of this article is to provide updated recommendations for the treatment of patients with stage IV non-small-cell lung cancer. A literature search identified relevant randomized trials published since 2002. The scope of the guideline was narrowed to chemotherapy and biologic therapy. An Update Committee reviewed the literature and made updated recommendations. One hundred sixty-two publications met the inclusion criteria. Recommendations were based on treatment strategies that improve overall survival. Treatments that improve only progression-free survival prompted scrutiny of toxicity and quality of life. For first-line therapy in patients with performance status of 0 or 1, a platinum-based two-drug combination of cytotoxic drugs is recommended. Nonplatinum cytotoxic doublets are acceptable for patients with contraindications to platinum therapy. For patients with performance status of 2, a single cytotoxic drug is sufficient. Stop first-line cytotoxic chemotherapy at disease progression or after four cycles in patients who are not responding to treatment. Stop two-drug cytotoxic chemotherapy at six cycles even in patients who are responding to therapy. The first-line use of gefitinib may be recommended for patients with known epidermal growth factor receptor (EGFR) mutation; for negative or unknown EGFR mutation status, cytotoxic chemotherapy is preferred. Bevacizumab is recommended with carboplatin-paclitaxel, except for patients with certain clinical characteristics. Cetuximab is recommended with cisplatin-vinorelbine for patients with EGFR-positive tumors by immunohistochemistry. Docetaxel, erlotinib, gefitinib, or pemetrexed is recommended as second-line therapy. Erlotinib is recommended as third-line therapy for patients who have not received prior erlotinib or gefitinib. Data are insufficient to recommend the routine third-line use of cytotoxic drugs. Data are insufficient to recommend routine use of molecular markers to select chemotherapy.

Molecular analysis-based treatment strategies for the management of non-small cell lung cancer

Even with the introduction of targeted agents and the establishment of multiple lines of therapy, the median survival for patients with advanced non-small cell lung cancer (NSCLC) does not considerably extend beyond 1 year. Emerging research suggests that clinical characteristics alone are insufficient for selecting patients for therapies that may confer significant survival benefit. The discovery of predictive and prognostic molecular markers such as gene mutations in EGFR and KRAS as well as high tumor expression levels of DNA repair pathway components ribonucleotide reductase subunit 1 and excision repair cross-complementing group 1 has sparked an interest in the development of individualized therapy as a strategy for increasing survival in patients with NSCLC. Techniques to analyze molecular biomarkers, such as immunohistochemistry, fluorescence in situ hybridization, polymerase chain reaction, and, more recently, gene microarray techniques, are being investigated for their potential to accurately predict an individual patient's response to therapy. Many prospective trials are still needed to clarify and confirm the utility of molecular biomarkers for guiding treatment selection, and continued participation in clinical trials is critical for the development of tools to provide customized treatment plans for patients with NSCLC.

Somatic EGFR mutations and efficacy of tyrosine kinase inhibitors in NSCLC

Early clinical studies of tyrosine kinase inhibitors (TKIs) that target the EGFR in patients with advanced non-small-cell lung cancer (NSCLC) showed that some patients experienced rapid, durable, complete or partial responses. These data were the basis for attempts to identify specific subgroups of patients who would further benefit from these agents. The discovery of somatic mutations in EGFR that correlated with sensitivity to TKIs identified a plausible explanation for these observations. Clinical and pathological factors such as female sex, never having smoked, Asian origin and adenocarcinoma histology correlate with the presence of EGFR mutations and objective responses to TKIs in patients with NSCLC. Recent studies in metastatic colorectal cancer highlighted that somatic mutations in KRAS represent a negative predictor of response to anti-EGFR monoclonal antibodies; KRAS mutations also represent an important mechanism of resistance to TKIs in NSCLC. Many large clinical studies are currently investigating the predictive and prognostic value of EGFR mutational status and other candidate biomarkers. We summarize the literature and present an overview of the field of anti-EGFR therapy in NSCLC, focusing on the influence of somatic EGFR mutations on selection of patients for TKI therapy and the influence of EGFR pathway regulation.

Combined survival analysis of prospective clinical trials of gefitinib for non-small cell lung cancer with EGFR mutations

PURPOSE

Somatic mutations of the epidermal growth factor receptor (EGFR) gene are associated with an increased response to gefitinib in patients with non-small cell lung cancer. We have examined the impact of gefitinib on progression-free survival and overall survival in patients with EGFR mutation-positive non-small cell lung cancer.

EXPERIMENTAL DESIGN

We searched for all clinical trials that prospectively evaluated the efficacy of gefitinib for advanced non-small cell lung cancer with EGFR mutations in Japan. We did a combined analysis based on individual patient data from the identified trials.

RESULTS

Seven eligible trials were identified for a total of 148 non-small cell lung cancer patients with EGFR mutations. The overall response rate to gefitinib was 76.4% [95% confidence interval (95% CI), 69.5-83.2]. The median progression-free survival and overall survival were 9.7 months (95% CI, 8.2-11.1) and 24.3 months (95% CI, 19.8-28.2), respectively. Good performance status and chemotherapy-naïve status were significantly associated with a longer progression-free survival or overall survival. Of the 148 patients, 87 received gefitinib as a first-line therapy, whereas 61 received systemic chemotherapy before gefitinib treatment. The median progression-free survival after the start of first-line therapy was significantly longer in the gefitinib-first group than in the chemotherapy-first group (10.7 versus 6.0 months; P < 0.001), whereas no significant difference in median overall survival was apparent between the two groups (27.7 versus 25.7 months; P = 0.782).

CONCLUSIONS

Gefitinib monotherapy confers substantial clinical benefit in terms of progression-free survival and overall survival in non-small cell lung cancer patients with EGFR mutations. Randomized trials comparing chemotherapy with gefitinib as a first-line treatment are warranted in such patients.

EGFR mutations are associated with prognosis but not with the response to front-line chemotherapy in the Chinese patients with advanced non-small cell lung cancer

The study aimed to investigate associations of tumor tissue EGFR mutations with response to the front-line chemotherapy and prognosis in advanced non-small cell lung cancer (NSCLC) patients. EGFR genotypes of 145 chemotherapy-naive patients with Stage IIIB and IV NSCLC were examined by using denaturing high-performance liquid chromatography (DHPLC). All patients received the front-line chemotherapy. There were 69 patients who received gefitinib therapy (32 as second-line and 37 as third-line therapy). About 37.9% (55/145) of the patients was detected to have EGFR mutations in their tumor tissue DNA. The response rate (RR, complete response plus partial response) to the chemotherapy for mutated EGFR carriers was 34.5% (19/55), similar to 33.3% (30/90) for wild-type EGFR carriers (P=0.881). The patients with EGFR mutations had increased median survival time and 1- and 2-year survival rate than those with wild-type EGFR (23 vs 16 months, 86.38% vs 62.64%, 38.78% vs 27.16%, P=0.0273). Among Stage IV NSCLC patients, mutated EGFR carriers had a longer progression-free survival (PFS) than wild-type EGFR carriers (5 vs 3 months, P=0.040). Cox multivariate regression analysis showed that response to the front-line chemotherapy (RR vs PD) and EGFR mutation were independent prognostic factors (HR=0.461, 95% CI: 0.271-0.783, P=0.0042; HR=0.598, 95% CI: 0.372-0.961, P=0.0335, respectively) for patients with advanced NSCLC. We conclude that EGFR mutations in the Chinese patients with advanced NSCLC were not associated with response to the front-line chemotherapy, but Stage IV NSCLC patients with mutated EGFR had a longer PFS after the front-line chemotherapy. EGFR mutation is an independent prognostic factor for Chinese advanced NSCLC.

Noninvasive detection of EGFR T790M in gefitinib or erlotinib resistant non-small cell lung cancer

PURPOSE

Tumors from 50% of epidermal growth factor receptor (EGFR) mutant non-small cell lung cancer patients that develop resistance to gefitinib or erlotinib will contain a secondary EGFR T790M mutation. As most patients do not undergo repeated tumor biopsies we evaluated whether EGFR T790M could be detected using plasma DNA.

EXPERIMENTAL DESIGN

DNA from plasma of 54 patients with known clinical response to gefitinib or erlotinib was extracted and used to detect both EGFR-activating and EGFR T790M mutations. Forty-three (80%) of patients had tumor EGFR sequencing (EGFR mutant/wild type: 30/13) and seven patients also had EGFR T790M gefitinib/erlotinib-resistant tumors. EGFR mutations were detected using two methods, the Scorpion Amplification Refractory Mutation System and the WAVE/Surveyor, combined with whole genome amplification.

RESULTS

Both EGFR-activating and EGFR T790M were identified in 70% of patients with known tumor EGFR-activating (21 of 30) or T790M (5 of 7) mutations. EGFR T790M was identified from plasma DNA in 54% (15 of 28) of patients with prior clinical response to gefitinib/erlotinib, 29% (4 of 14) with prior stable disease, and in 0% (0 of 12) that had primary progressive disease or were untreated with gefitinib/erlotinib.

CONCLUSIONS

EGFR T790M can be detected using plasma DNA from gefitinib- or erlotinib-resistant patients. This noninvasive method may aid in monitoring drug resistance and in directing the course of subsequent therapy.

Detection of K-Ras mutations in tumour samples of patients with non-small cell lung cancer using PNA-mediated PCR clamping

Non-small cell lung cancers (NSCLC), in particular adenocarcinoma, are often mixed with normal cells. Therefore, low sensitivity of direct sequencing used for K-Ras mutation analysis could be inadequate in some cases. Our study focused on the possibility to increase the detection of K-Ras mutations in cases of low tumour cellularity. Besides direct sequencing, we used wild-type hybridisation probes and peptide-nucleic-acid (PNA)-mediated PCR clamping to detect mutations at codons 12 and 13, in 114 routine consecutive NSCLC frozen surgical tumours untreated by targeted drugs. The sensitivity of the analysis without or with PNA was 10 and 1% of tumour DNA, respectively. Direct sequencing revealed K-Ras mutations in 11 out of 114 tumours (10%). Using PNA-mediated PCR clamping, 10 additional cases of K-Ras mutations were detected (21 out of 114, 18%, P<0.005), among which five in samples with low tumour cellularity. In adenocarcinoma, K-Ras mutation frequency increased from 7 out of 55 (13%) by direct sequencing to 15 out of 55 (27%) by clamped-PCR (P<0.005). K-Ras mutations detected by these sensitive techniques lost its prognostic value. In conclusion, a rapid and sensitive PCR-clamping test avoiding macro or micro dissection could be proposed in routine analysis especially for NSCLC samples with low percentage of tumour cells such as bronchial biopsies or after neoadjuvant chemotherapy.

Gefitinib for the treatment of non-small-cell lung cancer

Gefitinib is an orally bioavailable, EGF receptor tyrosine kinase inhibitor and was the first targeted drug to be approved for non-small-cell lung cancer (NSCLC). Identification of objective tumor regressions with gefitinib in NSCLC patients has resulted in intense, worldwide clinical and basic research directed toward finding the optimal use of gefitinib in NSCLC. A recent large international Phase III study (IRESSA NSCLC Trial Evaluating Response and Survival Against Taxotere [INTEREST]) comparing gefitinib and docetaxel in unselected pretreated patients showed equivalent survival with better tolerability and quality of life. In addition, a Phase III study (WJTOG0203) evaluating gefitinib as sequential therapy after platinum-doublet chemotherapy showed the improved progression-free survival time. Furthermore, a large-scale randomized study (IRESSA Pan-Asia study [IPASS]) comparing gefitinib monotherapy with carboplatin/paclitaxel for previously untreated patients with adenocarcinoma who were never- or light-smokers showed an improved progression-free survival time in the gefitinib arm. A smaller Phase III study of pretreated Japanese patients (V-15-32) also demonstrated no difference in overall survival compared with docetaxel, with a statistically greater overall response rate. Somatic mutations in the EGFR gene, the target of gefitinib, were associated with dramatic and durable regressions in patients with NSCLC. Currently, investigators are trying to determine the optimal approach to select patients for treatment with gefitinib. This article aims to briefly summarize the profile of gefitinib, EGFR mutations, landmark trials with gefitinib and, also, ongoing trials that may herald an era of individualized therapy in at least some NSCLC patients.

First-line gefitinib for patients with advanced non-small-cell lung cancer harboring epidermal growth factor receptor mutations without indication for chemotherapy

PURPOSE

This multicenter phase II study was undertaken to investigate the efficacy and feasibility of gefitinib for patients with advanced non-small-cell lung cancer (NSCLC) harboring epidermal growth factor receptor (EGFR) mutations without indication for chemotherapy as a result of poor performance status (PS).

PATIENTS AND METHODS

Chemotherapy-naïve patients with poor PS (patients 20 to 74 years of age with Eastern Cooperative Oncology Group PS 3 to 4, 75 to 79 years of age with PS 2 to 4, and >or= 80 years of age with PS 1 to 4) who had EGFR mutations examined by the peptide nucleic acid-locked nucleic acid polymerase chain reaction clamp method were enrolled and received gefitinib (250 mg/d) alone.

RESULTS

Between February 2006 and May 2007, 30 patients with NSCLC and poor PS, including 22 patients with PS 3 to 4, were enrolled. The overall response rate was 66% (90% CI, 51% to 80%), and the disease control rate was 90%. PS improvement rate was 79% (P < .00005); in particular, 68% of the 22 patients improved from >or= PS 3 at baseline to <or= PS 1. The median progression-free survival, median survival time, and 1-year survival rate were 6.5 months, 17.8 months, and 63%, respectively. No treatment-related deaths were observed.

CONCLUSION

This is the first report indicating that EGFR mutation-positive patients with extremely poor PS benefit from first-line gefitinib. Because there previously has been no standard treatment for these patients with short life expectancy other than best supportive care, examination of EGFR mutations as a biomarker is recommended in this patient population.

The role of the epidermal growth factor receptor tyrosine kinase inhibitors as therapy for advanced, metastatic, and recurrent non-small-cell lung cancer: a Canadian national consensus statement

PURPOSE

To provide consensus recommendations on the use of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIS) in patients with advanced or meta-static non-small-cell lung cancer (NSCLC).

METHODS

Using a systematic literature search, phase II trials, randomized phase III trials, and meta-analyses were identified for inclusion.

RESULTS

A total of forty-six trials were included. Clear evidence is available that EGFR-TKIS should not be administered concurrently with platinum-based chemotherapy as first-line therapy in advanced or metastatic nsclc. Evidence is currently insufficient to recommend single-agent EGFR-TKIS as first-line therapy either in unselected populations or in populations selected on the basis of molecular or clinical characteristics. Following failure of platinum-based chemotherapy, the evidence suggests that second-line EGFR-TKIS or second-line chemotherapy result in similar survival. Quality of life and symptom improvement for patients treated with an EGFR-TKI appear better than they do for patients treated with second-line docetaxel. Sequence of therapy may not appear to be important, but if survival is the outcome of interest, the goal should be to optimize the number of patients receiving three lines of therapy. Based on available data, molecular markers and clinical characteristics do not appear to be predictive of a differential survival benefit from an EGFR-TKI and therefore those factors should not be used to select patients for EGFR-TKI therapy.

CONCLUSIONS

The EGFR-TKIS represent an additional therapy in the treatment of advanced or metastatic NSCLC. The results of ongoing clinical trials may define the optimal role for these agents and the effectiveness of combinations of these agents with other targeted agents.

Association of epidermal growth factor receptor (EGFR) gene mutations with EGFR amplification in advanced non-small cell lung cancer

Somatic mutations in the epidermal growth factor receptor (EGFR) gene are associated with the response to EGFR tyrosine kinase inhibitors in patients with non-small cell lung cancer (NSCLC). Increased EGFR copy number has also been associated with sensitivity to these drugs. However, given that it is often difficult to obtain sufficient amounts of tumor tissue for genetic analysis from patients with advanced NSCLC, the relationship between these two types of EGFR alterations has remained unclear. We have now evaluated EGFR mutation status both by direct sequencing and with a high-sensitivity assay, the Scorpion-amplification-refractory mutation system, and have determined EGFR copy number by fluorescence in situ hybridization (FISH) analysis in paired tumor specimens obtained from 100 consecutive patients with advanced NSCLC treated with chemotherapy. EGFR mutations or FISH positivity (EGFR amplification or high polysomy) were apparent in 18% (18/100) and 32% (32/100) of patients, respectively. The Scorpion-amplification-refractory mutation system was more sensitive than direct sequencing for the detection of EGFR mutations. Furthermore, EGFR mutations were associated with EGFR amplification (P = 0.009) but not with FISH positivity (P = 0.266). Our results therefore suggest the existence of a significant association between EGFR mutation and EGFR amplification in patients with advanced NSCLC.

EGFR mutations and HER2/3 protein expression and clinical outcome in Chinese advanced non-small cell lung cancer patients treated with gefitinib

BACKGROUND

To assess the role of various epidermal growth factor receptor (EGFR) mutations and HER2/3 protein expression as predictive markers of responsiveness to gefitinib therapy in Chinese patients with advanced non-small cell lung cancer (NSCLC).

METHODS

A total of 106 Chinese NSCLC patients who had failed at least one chemotherapy regimen received gefitinib 250 mg once daily. All the 106 tumors from these patients were screened for mutations in the EGFR exons 18-24, and 84 tumors were studied by immunohistochemistry for HER2/3 expression and correlated with clinical treatment outcome.

RESULTS

Patients with EGFR mutations had a significantly higher overall response rate (ORR), longer time to progression (TTP) and overall survival (OS) compared with those with wild-type receptor. No difference in ORR was observed between patients with exon 19 deletion and patients with other EGFR mutations. ORR in HER2-positive patients was significantly higher than in the HER2-negative group, irrespective of EGFR mutational status, and a trend for better ORR was observed for HER3-positive patients. HER2 and HER3 expression levels were not associated with any difference in terms of TTP and OS. Nevertheless, when considering the subgroups of non-responders to gefitinib, median TTP in patients with mutated EGFR was significantly longer than in those with no mutations (8.0 vs. 3.0 months, P = 0.0065). EGFR-mutated patients had no significant difference in ORR, TTP and OS according to HER2 and/or HER3 expression.

CONCLUSIONS

EGFR mutations are effective predictors for gefitinib efficacy in Chinese patients with advanced NSCLC. HER2 and HER3 expression does not provide any additional information for selecting patients most likely to benefit from gefitinib treatment.

Prospective phase II study of gefitinib in non-small cell lung cancer with epidermal growth factor receptor gene mutations

BACKGROUND

This study prospectively assessed the efficacy of gefitinib and the survival benefit for non-small cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutations.

METHOD

Patients with either recurrent disease after undergoing surgery or advanced NSCLC disease (IIIB or IV) which demonstrated EGFR mutations were eligible for this study. EGFR mutations in exons 19-21 were examined. The patients with EGFR mutations were enrolled in this study after obtaining their informed consent a second time, and they were thereafter treated with gefitinib.

RESULTS

EGFR mutations were detected in 20 of 48 patients with NSCLC, and 19 patients were enrolled onto this study and treated with gefitinib. Seven patients had an exon 19 deletion, 10 had L858R, 1 had both, and 1 had an exon 19 deletion and G796A. The overall response rate was 63.2%, and the disease control rate was 89.5%. In patients with an exon 19 del and L858R, the response rates were 71.4% and 60.0%, respectively. The median progression-free survival time was 7.1 months, and the median survival time was 20.0 months. No life-threatening toxicity was observed. Four of five acquired resistant tumors showed an acquired T790M mutation.

CONCLUSIONS

EGFR mutations in exons 19 or 21 are considered to be a good predictor of the efficacy of gefitinib.

Clinical significance of pretreatment serum amphiregulin and transforming growth factor-alpha, and an epidermal growth factor receptor somatic mutation in patients with advanced non-squamous, non-small cell lung cancer

Circulating amphiregulin and transforming growth factor-alpha (TGF-alpha) have been found to be correlated with an unfavorable response to gefitinib based on the identification of patients with a higher probability of resistance to the drug. However, the association between an epidermal growth factor receptor (EGFR) somatic mutation and the overexpression of its ligands has not been determined. To verify the clinical significance of the two serum markers and EGFR mutation status, we determined serum amphiregulin and TGF-alpha levels by enzyme-linked immunosorbent assay in 93 patients with advanced non-squamous, non-small cell lung cancer and EGFR somatic mutation status using the peptic nucleic acid-locked nucleic acid clamp method in 46 cases. The relationship between each independent clinicopathological variable and the response to gefitinib therapy was examined. We also evaluated the risk factors associated with prognosis. Fourteen (41.0%) of 34 progressive disease cases were positive for amphiregulin (P = 0.007). Eleven (32.4%) of 34 progressive disease cases were positive for TGF-alpha (P = 0.005). The median survival time of patients with the EGFR somatic mutation was significantly longer (P = 0.01). The same was true of amphiregulin- (P = 0.046) and TGF-alpha-negative patients (P < 0.01). In multivariate analysis, serum TGF-alpha positivity (hazard ratio, 2.558; P = 0.005) and the wild type EGFR gene (hazard ratio, 1.894; P = 0.003) were significant independent prognostic factors. Our study demonstrates that the status of the serum EGFR ligand, in addition to EGFR activating mutation, is a predictive factor for response to gefitinib therapy.

Impact of EGFR mutation analysis in non-small cell lung cancer

The discovery of mutations in the tyrosine kinase domain of the epidermal growth factor receptor (EGFR) gene in non-small cell lung cancer (NSCLC) accelerated the research of molecular-targeted therapy by EGFR-tyrosine kinase inhibitors (TKIs), such as gefitinib and erlotinib. About 90% of EGFR mutations are clustered in exons 19 (deletion) and 21 (point mutation at codon 858) and patients with these mutations have great response to EGFR-TKIs. However, tumors that initially respond to EGFR-TKIs almost inevitably become resistant later and T790M secondary mutation in the EGFR gene and MET amplification are reported to account for the mechanism of this acquired resistance. In this review, we summarize the recent findings about EGFR mutations, amplification, alterations of other related genes and sensitivity and acquired resistance to EGFR-TKIs. We also discuss from our studies the relationship between EGFR mutations and other molecular alterations such as aberrant methylation in tumor suppressor genes (TSGs), which indicates that they are related to the mechanism of the pathogenesis of lung cancer. The accumulated important data confer further insights on translational research, providing us with the new strategies for the treatment of NSCLCs.

Somatic pharmacogenomics in cancer

Many of the initial examples of the clinical utility of pharmacogenetics were elucidated in the field of oncology. Those examples were largely based on the existence of germline genetic variation that influences the metabolism of cytotoxic drugs. However, with the development of kinase inhibitors, drugs designed to preferentially target altered proteins driving oncogenesis, pharmacogenetics in cancer has shifted to understanding the somatic differences that determine response to these targeted agents. It is becoming increasingly clear that understanding the molecular genetics of cancer will lead to the further development of targeted therapeutics. Therefore, it is imperative that pharmacogenomics researchers understand the motivations and challenges of developing targeted therapies to treat cancer as a paradigm for personalized medicine. However, much of the discussion in the pharmacogenomics community in cancer is still largely focused on the germline variants as predictors of drug toxicity. In light of that fact, this review presents a detailed discussion of the development of commonly used targeted therapies for the treatment of hematological and solid tumors, the somatic mutations that determine response to those therapies, and the mechanisms of drug resistance.

Specific EGFR mutations predict treatment outcome of stage IIIB/IV patients with chemotherapy-naive non-small-cell lung cancer receiving first-line gefitinib monotherapy

PURPOSE

To explore predictive factors for time to treatment failure (TTF) in chemotherapy-naive non-small-cell lung cancer (NSCLC) patients receiving gefitinib treatment.

PATIENTS AND METHODS

We designed a phase II study to test gefitinib antitumor efficacy in advanced-stage, chemotherapy-naive NSCLC patients. Patients were treated with gefitinib 250 mg/d. Tumor assessments were performed every 2 months. Responding or stable patients were treated until progression or unacceptable toxicity. All scans were reviewed independently. EGFR exons 18-21 sequence, K-ras exon 2 sequence, and MET gene copy numbers were examined in available samples. Clinical or molecular predictors of TTF were examined by multivariate analysis.

RESULTS

One hundred six patients were enrolled. Ninety patients had tumor samples for biomarker tests. Overall response rate was 50.9% (95% CI, 41.4% to 60.4%). Median TTF was 5.5 months, and median overall survival (OS) was 22.4 months. The response rate and median TTF of the patients with exon 19 deletion (n = 20) were 95.0% and 8.9 months, for exon 21 L858R mutation (n = 23) were 73.9% and 9.1 month, and for other types of EGFR mutations (N = 12) were 16.7% and 2.3 months, respectively. In multivariate analysis, the presence of EGFR deletion exon 19 or L858R EGFR mutations in adenocarcinoma patients predicted longer TTF. High copy number of MET seemed to correlate with shorter TTF in patients with gefitinib-sensitive activating EGFR mutations.

CONCLUSION

In this prospective study, EGFR exon 19 deletion or L858R mutations in adenocarcinoma were the best predictors for longer TTF in stage IIIB/IV chemotherapy-naive NSCLC patients receiving first-line gefitinib monotherapy.

Structure and clinical relevance of the epidermal growth factor receptor in human cancer

PURPOSE

To review the recent advances in the atomic-level understanding of the epidermal growth factor receptor (EGFR) tyrosine kinase (TK). We aim to highlight the current and future importance of these studies for the understanding and treatment of malignancies where EGFR-TK is improperly activated.

METHODS

The analysis was conducted on published crystal structures deposited in the Protein Data Bank (www.pdb.org) using the program O.

RESULTS

In this review we emphasize how recent EGFR kinase domain crystal structures can explain the mechanisms of activation for L858R and other EGFR-TK mutations, and compare these distinct activating mechanisms with those recently described for the wild-type EGFR. We suggest an atomic-level mechanism for the poor efficacy of lapatinib against tumors with activating EGFR kinase domain point mutations compared with the efficacy of gefitinib and erlotinib, and demonstrate how structural insights help our understanding of acquired resistance to these agents. We also highlight how these new molecular-level structural data are expected to affect the development of EGFR-TK targeted small molecule kinase inhibitors.

CONCLUSION

There are now more crystal structures published for the EGFR-TK domain than for any other TK. This wealth of crystallographic information is beginning to describe the mechanisms by which proper regulation of EGFR-TK is lost in disease. These crystal structures are beginning to show how small molecules inhibit EGFR-TK activity and will aid development of EGFR-TK mutant targeted therapies.

Overview of chemoradiation clinical trials for locally advanced non-small cell lung cancer in Japan

The standard of care for unresectable stage III non-small cell lung cancer (NSCLC) is combined-modality therapy with both chemotherapy and thoracic radiation therapy (TRT). A phase III trial by the West Japan Lung Cancer Group revealed that the combination of mitomycin, vindesine, and cisplatin (MVP) with concurrent TRT yielded a median survival time of 16.6 months and a 5-year survival rate of 16% in patients with unresectable stage III NSCLC. Although evidence indicates that concurrent chemotherapy and TRT (chemoradiation) increases survival to a moderately greater extent than sequential therapeutic approaches, the optimal strategies for such concurrent treatment remain to be defined, and differ between full-dose systemic and low-dose radio-enhancing protocols. Two phase III trials have been initiated in Japan to address these issues and they have recently reported preliminary data. Early results of the Okayama Lung Cancer Study Group (OLCSG) trial, comparing chemoradiation based on divided docetaxel and cisplatin chemotherapy with MVP-based chemoradiation, have been reported. The West Japan Oncology Group (WJOG) is comparing the efficacy and toxicity of TRT and concurrent chemotherapy with either carboplatin-paclitaxel or carboplatin-irinotecan, followed by full-dose consolidation chemotherapy, with the efficacy and toxicity of MVP-based chemoradiation. Several phase I/II studies to test the optimal use of new agents such as S-1 (an oral anticancer drug combining tegafur, 5-chloro-2, 4-dihydroxypyridine, and potassium oxonate) and gefitinib (an inhibitor of the tyrosine kinase activity of the epidermal growth factor receptor) are also ongoing. In addition, radiation dose intensification with three-dimensional planning approaches is currently under evaluation. A phase I clinical trial by WJOG to establish, prospectively, the maximum tolerated dose of three-dimensional hyperfractionated radiotherapy with concurrent weekly chemotherapy (carboplatin-paclitaxel) is thus currently under way. This overview of ongoing trials highlights new directions in the treatment of locally advanced NSCLC.

Lung adenocarcinoma: guiding EGFR-targeted therapy and beyond

Somatic mutations in certain tyrosine kinases have emerged as central 'drivers' of specific cancers and these mutant proteins are proving to be excellent substrates for targeted therapies. This is the case for mutant EGFR-dependent lung adenocarcinomas, where EGFR mutation testing is already being used to help guide treatment decisions. Here, we provide an overview of the biology of EGFR-targeted therapies and the clinical experience to date, the positive and negative predictors of response, pathologic correlates of EGFR-mutant status, testing methods to establish patient eligibility for these agents, and the basis for primary and secondary resistance.

Mutations in the epidermal growth factor receptor gene and effects of EGFR-tyrosine kinase inhibitors on lung cancers

Epidermal growth factor receptor (EGFR) gene mutations are frequent in lung cancer arising in patients of Asian ethnicity, female sex, nonsmokers, and adenocarcinoma histology. About 70% of the patients with EGFR mutations respond to EGFR tyrosine kinase inhibitors (TKIs) including gefitinib and erlotinib, whereas only 10% of those without the mutations do so. Therefore, EGFR mutation is being recognized as one of the most reliable predictive factors for treatment using EGFR-TKIs. Another important issue in clinical practice is the fatal interstitial lung disease (ILD) that can develop in patients with gefitinib treatment, especially Asian patients. A nested case-control study recently conducted in Japan identified some risk factors that cause ILD, including age > or = 55 years, a history of smoking, preexisting ILD, poor performance status, short duration since diagnosis of lung cancer, reduced extent of normal lung on computed tomography, and concurrent cardiac disease. About half of the acquired resistance to EGFR-TKIs that almost always occurs during the course of treatment is caused by a secondary mutation at codon 790 (T790M). EGFR-TKIs are not universally effective for treating lung cancers but are effective in patients with particular genotypes. Therefore, patients who would benefit from EGFR-TKIs therapy should be concentrated in clinical trials. Based on this concept, Phase III clinical trials comparing gefitinib monotherapy with standard platinum-based chemotherapy are currently ongoing for patients with EGFR mutations and lung cancer.

Peptide nucleic acid-locked nucleic acid polymerase chain reaction clamp-based detection test for gefitinib-refractory T790M epidermal growth factor receptor mutation

Mutations in the epidermal growth factor receptor (EGFR) are observed in a fraction of non-small-cell lung cancers (NSCLS). EGFR mutation-positive NSCLS responds to gefitinib. Secondary T790M mutation confers gefitinib resistance to NSCLS. A detection test for the T790M mutation was designed based on the peptide nucleic acid-locked nucleic acid polymerase chain reaction clamp method. The specificity and sensitivity of the test were both greater than 0.99. The test revealed that only a small population of the PC-13 cells carried the T790M mutation. The test also revealed that the T790M mutation was found in none of 151 NSCLC specimens obtained before gefitinib treatment, whereas it was found in four of four specimens obtained from NSCLS that had become refractory to gefitinib. In one patient in whom the L858R-positive EGFR allele was amplified to multiple copies, an L858R-T790M double-mutant allele emerged during the gefitinib therapy. This allele was expressed highly. The T790M mutation detection test based on the peptide nucleic acid-locked nucleic acid polymerase chain reaction clamp method is sensitive and specific, and is applicable to clinical practice. It detects T790M-positive cells in the course of gefitinib treatment, and thus will help to devise therapies effective for T790M-positive NSCLS.

Elevated serum level of sialylated glycoprotein KL-6 predicts a poor prognosis in patients with non-small cell lung cancer treated with gefitinib

PURPOSE

The factors affecting survival after gefitinib treatment in patients with non-small cell lung cancer (NSCLC) remain to be fully elucidated, although epidermal growth factor receptor (EGFR) mutation is a substantial prognostic factor. KL-6 has been studied as a useful indicator for interstitial lung diseases; however, it was first discovered as a lung cancer-related antigen. The aim of this study was to investigate the prognostic value of the serum KL-6 levels in advanced NSCLC patients treated with gefitinib and thus determine its association with the EGFR mutation status.

PATIENTS AND METHODS

Between September 2002 and September 2005, 41 patients with NSCLC were treated with gefitinib after having their serum KL-6 levels measured at Okayama University Hospital. EGFR mutations were analyzed by direct sequence methods.

RESULTS

The serum KL-6 levels ranged from 199 to 9080U/ml (median, 550U/ml), and 54% of 41 patients showed a level higher than the cut-off level of 500U/ml. The median progression-free survival (PFS) time and the median overall survival (OS) time were 4.7 months and 13.9 months, respectively. Multivariate analyses revealed that the elevated KL-6 level was an independent adverse prognostic factor for PFS (hazard ratio: 2.278, p=0.040) as well as OS (hazard ratio: 4.858, p=0.002) in NSCLC patients treated with gefitinib. The EGFR mutation status was analyzed in 22 patients (54%). Among those with wild-type EGFR, the patients with high serum KL-6 levels also had a worse survival than those within normal serum KL-6 levels (6.5 months versus 13.3 months, p=0.0194).

CONCLUSION

Our data suggest that NSCLC patients with high serum KL-6 levels tended to have a poor clinical outcome when treated with gefitinib.

Usefulness of FDG-PET for early prediction of the response to gefitinib in non-small cell lung cancer

Increased tumor uptake of (18)F-fluorodeoxyglucose (FDG) measured by positron emission tomography (PET) reflects glucose metabolism and proliferative activity of tumor cells. We conducted a study to assess the usefulness of FDG-PET for early prediction of the response to gefitinib, an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI), in advanced non-small cell lung cancer (NSCLC). Five NSCLC patients underwent FDG-PET to evaluate changes in FDG uptake at day 2 and 4 weeks after the initiation of gefitinib therapy compared with FDG-PET prior to therapy. FDG uptake was evaluated as the maximum standardized uptake value (SUVmax) of the target lesions, which were assessable by conventional CT. Based on the CT evaluation, two patients exhibited a partial response (PR), two patients had stable disease (SD) with a minor response, and one patient had progressive disease (PD). In patients with PR and SD, SUVmax decreased by 61+/-18% (standard deviation) and 59+/-12%, respectively, on day 2, and by 26+/-6 and 43+/-10%, respectively, at 4 weeks after the initiation of gefitinib. Two patients with SD had decreased FDG uptake within 2 days of initiation of therapy, and achieved progression-free survival (PFS) of more than 12 months. In contrast, SUVmax increased up to 153+/-21% at 2 days and 232+/-73% at 4 weeks in a patient with PD. The present preliminary study suggests that FDG-PET may be able to predict response to gefitinib in the early stage of therapy in patients with advanced NSCLC and may have a potential prognostic role.

Emergence of epidermal growth factor receptor T790M mutation during chronic exposure to gefitinib in a non small cell lung cancer cell line

The epidermal growth factor receptor (EGFR)-specific tyrosine kinase inhibitor gefitinib may provide dramatic clinical responses in some patients with pulmonary adenocarcinoma carrying activating mutations of the EGFR. However, prolonged administration of gefitinib may eventually induce acquired resistance in such patients. To gain insight into the mechanisms of this phenomenon, we placed PC-9, a cell line derived from pulmonary adenocarcinoma that has a 15-bp deletion in EGFR exon 19, under the continuous selective pressure of low levels of gefitinib without any mutagen, and established a subline that was able to grow in the presence of 2 micromol/L of gefitinib (designated RPC-9). In this cell line, about half of the reverse transcription-PCR products from mutated EGFR also carried an additional mutation (T790M). In keeping with the proposed role of T790M in abrogating gefitinib binding with EGFR, gefitinib-treated RPC-9 hardly displayed any decrease in the constitutive phosphorylation of EGFR, Akt, or Erk1/2 unlike in PC-9 cells. Interestingly, transfection of the EGFR carrying only a 15-bp deletion reversed the resistance to gefitinib in RPC-9 cells. Thus, the balance of expression levels between gefitinib-sensitive or gefitinib-resistant EGFR may govern the response to gefitinib in lung cancer.

Pooled analysis of the prospective trials of gefitinib monotherapy for EGFR-mutant non-small cell lung cancers

PURPOSE

Epidermal growth factor receptor (EGFR) mutations have been found in the majority of gefitinib-responsive non-small cell lung cancer (NSCLC) patients from retrospective studies. We sought to compile the available phase II and prospective trials of this EGFR tyrosine kinase inhibitor (TKI) to better understand the efficacy and safety of selecting patients to receive gefitinib based on their genotype.

DESIGN

We searched published trials involving EGFR-mutant patients and gefitinib. Five reports were identified (published between June 2006 and April 2007) in which gefitinib was given in a prospective manner to EGFR mutation positive patients at a dose of 250mg/day. Responses were determined by RECIST and toxicities by NCI-CTC.

RESULTS

A total of 101 patients were pooled from these studies. Fifty-nine received gefitinib as their first line of therapy and 42 after having received chemotherapy. The combined rate of complete and partial response (CR+PR) in the 99 measured patients was 80.8% (80/99) and only 7.1% (7/99) had progressive disease as best response. The response rate (CR+PR) for exon 19 deletion and L858R patients were 80.3% (53/66) and 81.8% (27/33), respectively. The median progression-free survival ranged from 7.7 to 12.9 months. Overall survival had not been reached in 4/5 reports and was 15.4 months in one of them. Gefitinib administration was safe (<50% of patients developed grades 1-2 skin rash or diarrhea) and interstitial lung disease was only reported in two patients (2%), without deaths.

CONCLUSIONS

Gefitinib monotherapy leads to objective responses in most patients with EGFR mutations. Both L858R and deletion 19 mutations derived similar clinical benefits. Small molecule TKIs are the new treatment paradigm for EGFR-mutant NSCLC.

Surgical resection after gefitinib treatment in patients with lung adenocarcinoma harboring epidermal growth factor receptor gene mutation

Gefitinib is the first approved epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) for the treatment of patients with advanced non-small cell lung cancer (NSCLC) who failed to respond to conventional chemotherapy. Gefitinib has fairly effective anti-tumour activity in patients with tumours harboring EGFR gene mutations. However, there has been no data about the preoperative gefitinib treatment in NSCLC patients. We reported here two cases of surgical resection of residual disease after dramatic response to gefitinib in patients with lung adenocarcinoma harboring EGFR gene mutation. Because both of our patients initially had advanced local tumour burden (bulky N2 disease), complete resection would not have been technically feasible. However, preoperative gefitinib treatment made it possible to achieve complete resection in both patients. We believe that clinical trials are required to evaluate the role of preoperative treatment of EGFR-TKIs in patients with locally advanced NSCLC harboring EGFR gene mutation.