Hideki Endoh

Reduced Expression of the let-7 MicroRNAs in Human Lung Cancers in Association with Shortened Postoperative Survival

In this study, we report for the first time reduced expression of the let-7 microRNA in human lung cancers. Interestingly, 143 lung cancer cases that had undergone potentially curative resection could be classified into two major groups according to let-7 expression in unsupervised hierarchical analysis, showing significantly shorter survival after potentially curative resection in cases with reduced let-7 expression (P = 0.0003). Multivariate COX regression analysis showed this prognostic impact to be independent of disease stage (hazard ratio = 2.17; P = 0.009). In addition, overexpression of let-7 in A549 lung adenocarcinoma cell line inhibited lung cancer cell growth in vitro. This study represents the first report of reduced expression of let-7 and the potential clinical and biological effects of such a microRNA alteration.

Mutations of the Epidermal Growth Factor Receptor Gene in Lung Cancer: Biological and Clinical Implications

Recently it has been reported that mutations in the tyrosine kinase domain of the epidermal growth factor receptor(EGFR) gene occur in a subset of patients with lung cancer showing a dramatic response to EGFR tyrosine kinase inhibitors. To gain further insights in the role of EGFR in lung carcinogenesis, we sequenced exons 18–21 of the tyrosine kinase domain using total RNA extracted from unselected 277 patients with lung cancer who underwent surgical resection and correlated the results with clinical and pathologic features. EGFR mutations were present in 111 patients (40%). Fifty-two were in-frame deletions around codons 746–750 in exon 19, 54 were point mutations including 49 at codon 858 in exon 21 and 4 at codon 719 in exon 18, and 5 were duplications/insertions mainly in exon 20. They were significantly more frequent in female (P < 0.001), adenocarcinomas (P = 0.0013), and in never-smokers (P < 0.001). Multivariate analysis suggested EGFR mutations were independently associated with adenocarcinoma histology (P = 0.0012) and smoking status (P < 0.001), but not with female gender (P = 0.9917). In adenocarcinomas, EGFR mutations were more frequent in well to moderately differentiated tumors (P < 0.001) but were independent of patient age, disease stages, or patient survival. KRAS and TP53 mutations were present in 13 and 41%, respectively. EGFR mutations never occurred in tumors with KRAS mutations, whereas EGFR mutations were independent of TP53 mutations. EGFR mutations define a distinct subset of pulmonary adenocarcinoma without KRAS mutations, which is not caused by tobacco carcinogens.

Mutations of the Epidermal Growth Factor Receptor Gene Predict Prolonged Survival After Gefitinib Treatment in Patients With Non–Small-Cell Lung Cancer With Postoperative Recurrence

PURPOSE To evaluate the relationship between mutations of the epidermal growth factor receptor (EGFR) gene and the effectiveness of gefitinib treatment in patients with recurrent lung cancer after pulmonary resection. PATIENTS AND METHODS We sequenced exons 18-21 of the EGFR gene using total RNA extracted from 59 patients with lung cancer who were treated with gefitinib for recurrent lung cancer. Gefitinib effectiveness was evaluated by both imaging studies and change in serum carcinoembryonic antigen (CEA) levels. RESULTS EGFR mutations were found in 33 patients (56%). Of these mutations, 17 were deletions around codons 746-750 and 15 were point mutations (12 at codon 858, three at other codons), and one was an insertion. EGFR mutations were significantly more prevalent in females, adenocarcinoma, and never-smokers. Gefitinib treatment resulted in tumor shrinkage and/or CEA decrease to less than half of the baseline level in 26 patients, tumor growth and/or CEA elevation in 24 patients, and gefitinib effect was not assessable in nine patients. Female, never-smoking patients with adenocarcinoma tended to respond better to gefitinib treatment. Gefitinib was effective in 24 of 29 patients with EGFR mutations, compared with two of 21 patients without mutations (P < .0001). Of note, del746-750 might be superior to L858R mutations for prediction of gefitinib response. Patients with EGFR mutations survived for a longer period than those without the mutations after initiation of gefitinib treatment (P = .0053). CONCLUSION EGFR mutations were a good predictor of clinical benefit of gefitinib in this setting.

Analysis of Epidermal Growth Factor Receptor Gene Mutation in Patients with Non–Small Cell Lung Cancer and Acquired Resistance to Gefitinib

Purpose: Non–small cell lung cancers carrying activating mutations in the gene for the epidermal growth factor receptor (EGFR) are highly sensitive to EGFR-specific tyrosine kinase inhibitors. However, most patients who initially respond subsequently experience disease progression while still on treatment. Part of this “acquired resistance” is attributable to a secondary mutation resulting in threonine to methionine at codon 790 (T790M) of EGFR. Experimental Design: We sequenced exons 18 to 21 of the EGFR gene to look for secondary mutations in tumors with acquired resistance to gefitinib in 14 patients with adenocarcinomas. Subcloning or cycleave PCR was used in addition to normal sequencing to increase the sensitivity of the assay. We also looked for T790M in pretreatment samples from 52 patients who were treated with gefitinib. We also looked for secondary KRAS gene mutations because tumors with KRAS mutations are generally resistant to tyrosine kinase inhibitors. Results: Seven of 14 tumors had a secondary T790M mutation. There were no other novel secondary mutations. We detected no T790M mutations in pretreatment specimens from available five tumors among these seven tumors. Patients with T790M tended to be women, never smokers, and carrying deletion mutations, but the T790M was not associated with the duration of gefitinib administration. None of the tumors had an acquired mutation in the KRAS gene. Conclusions: A secondary T790M mutation of EGFR accounted for half the tumors with acquired resistance to gefitinib in Japanese patients. Other drug-resistant secondary mutations are uncommon in the EGFR gene.

Prognostic Model of Pulmonary Adenocarcinoma by Expression Profiling of Eight Genes As Determined by Quantitative Real-Time Reverse Transcriptase Polymerase Chain Reaction

PURPOSE Recently, several expression-profiling experiments have shown that adenocarcinoma can be classified into subgroups that also reflect patient survival. In this study, we examined the expression patterns of 44 genes selected by these studies to test whether their expression patterns were relevant to prognosis in our cohort as well, and to create a prognostic model applicable to clinical practice. PATIENTS AND METHODS Expression levels were determined in 85 adenocarcinoma patients by quantitative reverse transcriptase polymerase chain reaction. Cluster analysis was performed, and a prognostic model was created by the proportional hazards model using a stepwise method. RESULTS Hierarchical clustering divided the cases into three major groups, and group B, comprising 21 cases, had significantly poor survival (P =.0297). Next, we tried to identify a smaller number of genes of particular predictive value, and eight genes (PTK7, CIT, SCNN1A, PGES, ERO1L, ZWINT, and two ESTs) were selected. We then calculated a risk index that was defined as a linear combination of gene expression values weighted by their estimated regression coefficients. The risk index was a significant independent prognostic factor (P =.0021) by multivariate analysis. Furthermore, the robustness of this model was confirmed using an independent set of 21 patients (P =.0085). CONCLUSION By analyzing a reasonably small number of genes, patients with adenocarcinoma could be stratified according to their prognosis. The prognostic model could be applicable to future decisions concerning treatment.

Prognostic and predictive implications of HER2/ERBB2/neu gene mutations in lung cancers

BACKGROUND Activating mutation in the kinase domain of the human EGF receptor 2 (HER2) gene (also known as ERBB2 or neu) is reported to be present in a small fraction of lung adenocarcinomas. However its prognostic and predictive implications are not yet established. PATIENTS AND METHODS We examined 504 Japanese lung cancer patients who underwent pulmonary resection for HER2 mutations by direct sequencing and evaluated their prognostic and predictive implications. Updated prognostic data of 14 Japanese patients with HER2 mutation from previous two reports were also gathered. RESULTS HER2 mutations were identified in 13 of 504 cases (2.6%). Patients with HER2 mutations were common in female, nonsmokers and adenocarcinomas as those with EGFR mutations. When confined to the subgroup of nonsmokers with adenocarcinoma or adenosquamous cell carcinoma without EGFR mutations, the frequency of HER2 mutations was 14.1% (11/78). There was no difference in the overall survival of patients with HER2 mutations, compared with patients harboring EGFR mutations and patients harboring wild types for both EGFR and HER2. Within the patients with HER2 mutation, two of three with TP53 mutation and one of 13 without TP53 mutation died of the disease, suggesting negative prognostic role of the TP53 mutation. Three patients with HER2 mutations did not respond to platinum-based chemotherapy and EGFR-TKIs. Of note, one patient with the most common HER2 mutations, YVMA776-779ins, responded to trastuzumab plus vinorelbine after failure of multiple round of platinum-based chemotherapy and gefitinib. CONCLUSION HER2 mutations are present in a subset of patients with lung cancer having distinct clinical features. HER2 mutations were not associated with the prognosis of patients with lung cancers. Patients with HER2 mutations might benefit from anti-HER2 therapy.

PTEN and PIK3CA Expression Is Associated with Prolonged Survival after Gefitinib Treatment in EGFR-Mutated Lung Cancer Patients

Background: We and other researchers have previously reported that pulmonary adenocarcinomas with epidermal growth factor receptor (EGFR) mutations are usually sensitive to gefitinib, an EGFR-specific tyrosine kinase inhibitor, although this relationship is not complete. In this study, we searched for mutations or changes in the expression of genes downstream to EGFR and evaluated their relationship with the effectiveness of gefitinib. Methods: We studied 78 lung cancer patients who had recurrent disease after surgical resection and were treated with gefitinib. We searched for mutations occurring in the KRAS and PIK3CA gene. We also evaluated the expression level of EGFR, PIK3CA, and PTEN by real-time reverse transcriptase polymerase chain reaction. Gefitinib effectiveness was evaluated by imaging studies; a survival analysis was also done. Results: We found seven (9%) somatic mutations in KRAS and two (2%) in PIK3CA. EGFR mutations were present in 44 (56%). KRAS mutations were found only in tumors without EGFR mutations, whereas PIK3CA mutation was found in tumors with EGFR mutation. Tumor response was assessable in 52 tumors. None of the six tumors with KRAS mutations responded to gefitinib treatment; however, two tumors with PIK3CA mutations showed partial response. Survival was significantly longer in patients with EGFR mutations or in those without KRAS mutations. In tumors with EGFR mutations, survival was longer in those with high PIK3CA or PTEN expression than in those with low expression of these molecules. Conclusions: An evaluation of the KRAS mutation, as well as PIK3CA and PTEN expression, might help identify lung cancer patients who are most suitable for gefitinib treatment.

FBXW7 Mediates Chemotherapeutic Sensitivity and Prognosis in NSCLCs

Non–small cell lung cancer (NSCLC) is a leading cause of cancer-related deaths worldwide. To improve the prognosis of patients with NSCLCs, new and validated therapeutic targets are critically needed. In this study, we focused on F-box and WD repeat domain containing-7 (FBXW7), an E3 ubiquitin ligase, that regulates the degradation of MCL1, Myc, cyclin E, and TOP2A. Importantly, loss of FBXW7 was associated with increased sensitivity of tumors to a class I–specific histone deacetylase (HDAC) inhibitor, MS-275. Immunohistochemical analysis revealed increased expression of FBXW7 targets, MCL1 and TOP2A, in NSCLC tumors with low expression of FBXW7. Moreover, clinical specimens exhibiting low FBXW7 expression presented with more progressive cancer and significantly shorter cancer-specific survival than patients with high FBXW7 expression. Mechanistic study of NSCLC cell lines with silenced FBXW7 revealed enhanced MS-275 sensitivity and taxol resistance. Interestingly, taxol resistance was eliminated by MS-275 treatment, suggesting the potential of HDAC inhibitors for the treatment of aggressive taxol-resistant NSCLCs that lack FBXW7. Implications: FBXW7 status impacts chemosensitivity and is a prognostic marker in NSCLCs. Visual Overview: http://mcr.aacrjournals.org/content/early/2013/12/19/1541-7786.MCR-13-0341/F1.large.jpg. Mol Cancer Res; 12(1); 32–37. ©2013 AACR.

Pulmonary function after pulmonary resection by posterior thoracotomy, anterior thoracotomy or video-assisted surgery

OBJECTIVE Predicted postoperative forced expiratory volume in 1s (ppoFEV1) is estimated in lung cancer patients before pulmonary resection, as well as the clinical stage. This study aims to evaluate ppoFEV1 and ppo-vital capacity (ppoVC) on postoperative day 7 (POD7) and to compare the results following video-assisted thoracic surgery (VATS) and open thoracotomy procedures. METHODS Of the 155 patients who underwent pulmonary resection, 70 had VATS; 30 had muscle-sparing thoracotomy (anterior limiting thoracotomy (AL)); and 55 had postero-lateral thoracotomy (PL). VC and FEV1 were measured on POD7 and compared with the VC and FEV1 before surgery using analysis of covariance (ANCOVA). The ratio of the actual- and the ppoVC and FEV1 was evaluated to identify factors associated with variations in postoperative residual VC/FEV1. RESULTS There were significant differences by analysis of covariance (ANCOVA) in the VC/FEV1 among the three surgical approaches. In the VATS group, the VC ratio and the FEV1 ratio were 96.5% and 94.7%, respectively; they were significantly higher in the VATS group than in the thoracotomy group (AL: 90.4% and 90.1%, respectively; PL: 87.4% and 87.6%, respectively). Non-chronic obstructive pulmonary disease (COPD) and upper lobectomy were also associated with a low VC ratio and FEV1 ratio. CONCLUSION Predicted postoperative pulmonary function might be overestimated in COPD patients or in those undergoing VATS or lower lobectomy.

Immunohistochemical analysis of phosphorylated epidermal growth factor receptor might provide a surrogate marker of EGFR mutation

PURPOSE Overexpression of EGFR is found in several malignancies including lung cancers. Recently, EGFR mutation has been shown to correlate with responsiveness to tyrosine kinase inhibitors (TKI). Although antibodies against phophorylated EGFR have been used in vitro, phosphorylated EGFR has yet not been examined well in resected non-small cell lung cancers (NSCLCs). EXPERIMENTAL DESIGN We studied the immunohistochemistry of anti-EGFR and phosphorylated EGFR in 97 resected NSCLCs, examined the relationship with EGFR mutation, and performed quantitative RT-PCR of the EGFR gene in the TaqMan assay. RESULT EGFR mutation was seen in 27% of 97 NSCLCs and 37% of 70 adenocarcinomas. EGFR was stained in 60% of 97 NSCLCs. Phosphorylation of tyrosine 845 (pY845) and 1068 (pY1068) was positive in 49% and 48%, respectively. The observed correlation with EGFR mutation and pY845 or pY1068 was statistically significant (P=0.0001 for pY845, P<0.0001 for pY1068, chi square test), although phospho-EGFR status was not associated with a particular mutation type. pY1068-positive tumors also correlated with female, light smoker, and adenocarcinoma histology, but not with mRNA expression. Moreover, patients with pY1068-positive tumors showed prolonged survival (P=0.0093, log-rank test). CONCLUSION It is possible that immunohistochemistry of phosphorylated EGFR can substitute for EGFR mutation analysis. Further investigation is necessary to determine whether phospho-EGFR immunohistochemistry predicts response to TKIs and survival benefit.