Monitoring of Current Cancer Therapy by Positron Emission Tomography and Possible Role of Radiomics Assessment.

Evaluation of cancer therapy with imaging is crucial as a surrogate marker of effectiveness and survival. The unique response patterns to therapy with immune-checkpoint inhibitors have facilitated the revision of response evaluation criteria using FDG-PET, because the immune response recalls reactive cells such as activated T-cells and macrophages, which show increased glucose metabolism and apparent progression on morphological imaging. Cellular metabolism and function are critical determinants of the viability of active cells in the tumor microenvironment, which would be novel targets of therapies, such as tumor immunity, metabolism, and genetic mutation. Considering tumor heterogeneity and variation in therapy response specific to the mechanisms of therapy, appropriate response evaluation is required. Radiomics approaches, which combine objective image features with a machine learning algorithm as well as pathologic and genetic data, have remarkably progressed over the past decade, and PET radiomics has increased quality and reliability based on the prosperous publications and standardization initiatives. PET and multimodal imaging will play a definitive role in personalized therapeutic strategies by the precise monitoring in future cancer therapy.

The necessity of routine screening for deep vein thrombosis before surgery.

Background: Pulmonary embolism (PE) from deep venous thrombosis (DVT) can be a fatal postoperative complication. Preventive measures for venous thromboembolism (VTE) was evaluated in this hospital. Materials and methods: Preoperative DVT screening following surgery under general anesthesia in 2009-2016 was examined, and then, 217 patients diagnosed with DVT by preoperative leg-ultrasound (US) between 2014 and 2016 were retrospectively analyzed. Results: There were 24,826 operations under general anesthesia in the study period. Preoperative leg-US was performed in 5345 (21.5%) patients, and 648 (12.1% of patients, 2.6% of total operations) were diagnosed with DVT. In 2014-2016, 217 patients, which is 11.7% of patients undergoing leg-US, were diagnosed with DVT. DVT was found in the proximal veins (upper popliteal vein) in 86 (39.6%) patients. A total of 143 (62%) patients were considered to have organized thrombi, no patient developed pulmonary embolism, and 133 (58%) patients were discharged without follow-up examination for DVT. Ninety-six patients were evaluated for changes on leg-US, with no difference in the results with and without anticoagulant use. On multivariate logistic regression analysis, anticoagulants appeared effective for non-organized thrombi, higher D-dimer levels (≥10 µg/mL), or orthopedic surgery. Conclusion: Preoperative screening for DVT did not appear useful, and treatment of asymptomatic DVT was not always necessary.

Clinical Outcomes of Postoperative Adjuvant Chemotherapy for Surgically Resected High-Grade Pulmonary Neuroendocrine Carcinoma.

INTRODUCTION: Data on the clinical outcomes of patients receiving adjuvant chemotherapy for surgically resected high-grade pulmonary neuroendocrine carcinoma (HGNEC) (large-cell neuroendocrine carcinoma and small-cell lung cancer) are limited. This study aimed to evaluate the prognostic significance of adjuvant chemotherapy in patients with HGNEC. METHODS: We retrospectively analyzed patients with surgically resected HGNEC at five institutions in Japan between January 2006 and May 2016. RESULTS: A total of 143 patients were enrolled. Among them, 65 received adjuvant chemotherapy. Four patients who participated in clinical trials were excluded; the remaining 61 patients were included in the study. Fifty-six patients received adjuvant small-cell lung cancer-based chemotherapy. Twenty-five of 29 patients who relapsed after postoperative adjuvant chemotherapy received chemotherapy. The most commonly administered chemotherapy agent was amrubicin. The 3-year relapse-free and overall survival rates were 55.2% and 66.8%, respectively. The median relapse-free and overall survival times for the 25 patients who received chemotherapy after relapse were 12.9 and 27.5 months, respectively. Among them, 22 relapsed within 2 years. Patients who received platinum-doublet chemotherapy after relapse tended to have better time to progression disease and overall survival than those who received single-agent chemotherapy. CONCLUSIONS: Most patients with HGNEC received small-cell lung cancer-based regimens as postoperative adjuvant chemotherapy. Those who relapsed after adjuvant chemotherapy were mainly treated with amrubicin. Our findings suggest that platinum-doublet chemotherapy tends to improve the time to progression disease and overall survival in patients who relapse after postoperative adjuvant chemotherapy.

Clinicopathologic Significance of False-Positive Lymph Node Status on FDG-PET in Lung Cancer.

INTRODUCTION: 2-[18F] Fluoro-d-deoxyglucose (FDG) positron emission tomography (PET) is a relevant diagnostic procedure for staging lung cancer. However, accurate evaluation of lymph node metastases by PET is controversial because of false-positive FDG uptake. PATIENTS AND METHODS: A total of 245 patients with lung cancer were retrospectively analyzed. Standardized maximum uptake values (SUVmax) of the primary tumor and lymph nodes were compared to pathologic lymph node metastases to correlate PET findings with clinicopathologic variables and patient outcomes. RESULTS: The SUVmax values of metastatic lymph nodes were significantly higher than those of lymph nodes without metastases (P = .0036). When SUVmax ≥ 4 was defined as PET positive for metastasis, the sensitivity, specificity, and accuracy were 48.1%, 79.8%, and 73.1%, respectively. Multivariate logistic regression analysis showed that age > 75 years, bilateral hilar FDG uptake, and no lymph node swelling were significant factors related to false-positive lymph node metastases. Smoking status, FDG uptake in the primary tumor, and concurrent lung diseases were not significant factors. CONCLUSION: Metastatic lymph nodes show higher FDG uptake than false-positive lymph nodes, and older patient age, bilateral hilar FDG uptake, and no swollen nodes are associated with no metastases. Patients with lymph node metastases have worse survival than those with false-positive FDG-PET findings. However, abnormal FDG uptake in the lymph node is an important prognostic factor.

Prognostic impact of preoperative FDG-PET positive lymph nodes in lung cancer.

BACKGROUND: 2-[18F] Fluoro-D-deoxyglucose positron emission tomography (FDG-PET) is an appropriate diagnostic procedure for staging lung cancer. However, accurate evaluation of lymph node (LN) metastases by PET is controversial owing to false-positive/-negative FDG uptake results. The prognostic significance of both false-negative and false-positive LNs on FDG-PET remains to be determined. METHODS: A total of 235 patients with lung cancer were retrospectively analyzed. Maximum standardized uptake values (SUVmax) of the lymph nodes were compared with pathological LN metastases to correlate PET findings with clinicopathological variables and patients' outcomes. RESULTS: When SUVmax ≥ 4 was defined as PET-positive for LN metastasis, sensitivity, specificity, and accuracy were 46.0%, 79.5%, and 72.3%, respectively. False-negative cases and pathological n0 cases were significantly younger, had primary tumors that were smaller or lower SUVmax, and adenocarcinomas compared with false-positive and pathological n+ cases. The difference in survival time between patients with abnormal FDG uptake in the LN and those without was larger than that between pathological LN metastases and no pathological metastases in patients with adenocarcinoma. Multivariate analysis by the Cox proportional hazard model identified smoker, EGFR/ALK negative and LN positive on PET as significant adverse prognostic factors, rather than pathological n-stage. CONCLUSIONS: Abnormal FDG uptake in the LN is an important prognostic factor. Increased glucose metabolism on FDG-PET appears to be a more efficient postoperative prognostic marker than pathological n-stage in patients with lung cancer.

Prognostic Significance of Glucose Metabolism as GLUT1 in Patients with Pulmonary Pleomorphic Carcinoma.

Glucose metabolism is necessary for tumor progression, metastasis, and survival in various human cancers. Glucose transporter 1 (GLUT1), in particular, plays an important role in the mechanism of ¹8F-FDG (2-[¹8F]-fluoro-2-deoxy-d-glucose) within tumor cells. However, little is known about the clinicopathological significance of GLUT1 in patients with pulmonary pleomorphic carcinoma (PPC). Adenocarcinoma, squamous cell carcinoma, adenosquamous cell carcinoma, poorly differentiated carcinoma, large cell carcinoma, and others were identified as epithelial components, and spindle-cell type, giant-cell type, and both spindle- and giant-cell types were identified as sarcomatous components. This study was performed to determine the prognostic impact of GLUT1 expression in PPC. Patients with surgically resected PPC (n = 104) were evaluated by immunohistochemistry analysis to detect GLUT1 expression and determine the Ki-67 labeling index using specimens of the resected tumors. GLUT1 was highly expressed in 48% (50/104) of all patients, 42% (20/48) of the patients with an adenocarcinoma component, and 53% (30/56) of the patients with a nonadenocarcinoma component. High expression of GLUT1 was significantly associated with advanced stage, vascular invasion, pleural invasion, and tumor cell proliferation as determined by Ki-67 labeling. GLUT1 expression and tumor cell proliferation were significantly correlated according to the Ki-67 labeling in all patients (Spearman's rank; r = 0.25, p < 0.01). In multivariate analysis, GLUT1 was identified as a significant independent marker for predicting a poor prognosis. GLUT1 is an independent prognostic factor for predicting the poor prognosis of patients with surgically resected PPC.

Prognostic Significance of Tumor Immunity in Surgically Resected Pulmonary Pleomorphic Carcinoma.

BACKGROUND: Pulmonary pleomorphic carcinoma (PPC) is a rare aggressive neoplasm, with dismal prognosis. Whether tumor immunity is associated with the progressive biological behavior of PPC remains unclear. The purpose of this study was to examine the prognostic significance of tumor immunity-related markers such as programmed death-1 ligand (PD-L1) and CD4+ or CD8+ tumor-infiltrating lymphocytes (TILs) in patients with surgically resected PPC. PATIENTS AND METHODS: Ninety-nine patients with surgically resected PPC were assessed by immunohistochemistry. The expression of PD-L1, CD4, and CD8 was examined in specimens of the resected tumors. RESULTS: PD-L1 was highly expressed in 61% (60/99) of lesions and high expression of CD4 and CD8 was identified in 42% (42/99) and 51% (51/99) of lesions, respectively. There was no relationship between the expression PD-L1 and the numbers of CD4+ or CD8+ TILs. The expression of PD-L1 was not identified as a significant prognostic marker; however, a low number of CD4+ TILs was identified as an independent marker for predicting a worse outcome after surgical resection of PPC, especially in patients with an epithelial component of adenocarcinoma or early stage of disease. By univariate analysis, a low number of CD8+ TILs was found to be a significant prognostic marker linked to poor overall survival in patients with non-adenocarcinoma components. CONCLUSION: A low number of CD4+ TILs is an independent marker for predicting a favorable prognosis after surgical resection in patients with PPC, especially in patients with adenocarcinoma components or early stage of disease.

Clinical Significance of Various Drug-Sensitivity Markers in Patients with Surgically Resected Pulmonary Pleomorphic Carcinoma.

Various drug-sensitivity markers are potentially responsible for tumor progression and chemotherapy resistance in cancer patients with both epithelial and sarcomatous components; however, the clinicopathological significance of drug-sensitivity markers in patients with pulmonary pleomorphic carcinoma (PPC) remains unknown. Here, we clarified the prognostic impact of these drug-sensitivity markers in PPC by performing immunohistochemical and clinicopathologic analyses of samples from 105 patients with surgically resected PPC in order to evaluate levels of vascular endothelial growth factor 2 (VEGFR2), stathmin 1 (STMN1), tubulin ß3 class III (TUBB3), thymidylate synthetase (TS), topoisomerase II (Topo-II), glucose-regulated protein, and 78 kDa (GRP78)/binding immunoglobulin protein (BiP). We observed the rates of high expression for VEGFR2, STMN1, TUBB3, TS, Topo-II, and GRP78/BiP were 33% (39/105), 35% (37/105), 61% (64/105), 51% (53/105), 31% (33/105), and 51% (53/105) of the samples, respectively. Moreover, multivariate analysis identified VEGFR2 and GRP78/BiP as significant independent markers for predicting worse prognosis. These findings suggested elevated VEGFR2 and decreased GRP78/BiP levels as independent factors for predicting poor outcomes following surgical resection in patients with PPC.

Thoracoscopic surgery using omental flap for bronchopleural fistula.

BACKGROUND: A bronchopleural fistula (BPF) can lead to empyema and death after pulmonary resection. A minor leakage from a BPF has been reported to be successfully closed endobronchially, although thoracoplasty is usually needed. CASE PRESENTATION: A case of successful thoracoscopic BPF closure using an omental flap in a 74-year-old man with emphysema who developed a BPF after right lower lobectomy for lung cancer is reported. Reoperation was performed to close the BPF using an omental flap. After successful closure of the BPF, the empyema resolved with intravenous antibiotics. CONCLUSIONS: Thoracoscopic single-stage omentoplasty without thoracotomy might be a useful treatment method when a BPF is diagnosed early.

Prognostic Impact of ß2 Adrenergic Receptor Expression in Surgically Resected Pulmonary Pleomorphic Carcinoma.

BACKGROUND/AIM: The ß2-adrenergic receptor (ß2AR) is highly expressed in various human cancers and has been linked to tumor growth and metastases. Although ß2AR is considered a novel therapeutic target of human neoplasms, the clinicopathological significance of ß2AR expression in patients with pulmonary pleomorphic carcinoma (PPC) remains unclear. The aim of this study was to clarify the prognostic impact of ß2AR in PPC. PATIENTS AND METHODS: One hundred and five Japanese patients with surgically resected PPC were included in the study. The expression levels of ß2AR were assessed by immunohistochemistry in specimens from the resected tumors, and their association with patient survival, as well as with tumor characteristics was investigated. RESULTS: ß2AR was highly expressed in 63% of all patients, irrespective of adenocarcinoma components present. The ß2AR expression was significantly associated with lymph node metastasis, lymphatic permeation and tumor cell proliferation in PPC patients with early-stage disease (stage I or II). A high ß2AR expression was identified as a significant predictor of worse prognosis for PPC patients during early stages of the disease. Multivariate analysis confirmed that ß2AR expression was an independent factor for predicting the overall survival of PPC patients. CONCLUSION: ß2AR can serve as a significant predictor of tumor aggressiveness and poor survival for PPC patients, especially those with early-stage disease.

Response Heterogeneity of EGFR and HER2 Exon 20 Insertions to Covalent EGFR and HER2 Inhibitors.

Insertion mutations in EGFR and HER2 both occur at analogous positions in exon 20. Non-small cell lung cancer (NSCLC) patients with tumors harboring these mutations seldom achieve clinical responses to dacomitinib and afatinib, two covalent quinazoline-based inhibitors of EGFR or HER2, respectively. In this study, we investigated the effects of specific EGFR and HER2 exon 20 insertion mutations from NSCLC patients that had clinically achieved a partial response after dacomitinib treatment. We identified Gly770 as a common feature among the drug-sensitive mutations. Structural modeling suggested that this mutation may facilitate inhibitor binding to EGFR. Introduction of Gly770 into two dacomitinib-resistant EGFR exon 20 insertion mutants restored sensitivity to dacomitinib. Based on these findings, we used afatinib to treat an NSCLC patient whose tumor harbored the HER2 V777_G778insGSP mutation and achieved a durable partial response. We further identified secondary mutations in EGFR (T790M or C797S) and HER2 (C805S) that mediated acquired drug resistance in drug-sensitive EGFR or HER2 exon 20 insertion models. Overall, our findings identified a subset of EGFR and HER2 exon 20 insertion mutations that are sensitive to existing covalent quinazoline-based EGFR/HER2 inhibitors, with implications for current clinical treatment and next-generation small-molecule inhibitors. Cancer Res; 77(10); 2712-21. ©2017 AACR.

FBXW7 mediates chemotherapeutic sensitivity and prognosis in NSCLCs.

UNLABELLED: 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.

Risk analysis of pulmonary resection for elderly patients with lung cancer.

PURPOSE: The indications for pulmonary resection in elderly patients with lung cancer concomitant with another disease are unclear. We conducted this retrospective study to establish the risk factors of complications and survival to improve patient selection. METHODS: The subjects were 295 patients aged ≥ 75 years, who underwent pulmonary resection for lung cancer. We assessed comorbidity according to the Charlson comorbidity index (CCI) and examined risk factors for morbidity and the prognostic factors. RESULTS: Postoperative complications developed in 55 patients (morbidity 18.6 %). The median survival time was 59.3 months and the 5-year survival rate was 69.7 %. Multivariate logistic regression analyses selected smoking and thoracotomy as risk factors for complications, and a history of cerebrovascular disease, cancer stage, and thoracotomy as risk factors for a prolonged hospital stay (PHS). Video-assisted thoracic surgery (VATS) decreased the risk of morbidity and PHS, and influenced survival. Multivariate analysis with the Cox proportional hazard model identified CCI ≥ 2, morbidity, and PHS as unfavorable survival factors, in addition to age ≥ 80 and cancers that were non-adenocarcinoma or advanced. CONCLUSIONS: Although CCI ≥ 2 was associated with poorer survival, it was not necessarily a risk factor of postoperative complications or PHS. Performing VATS when possible could reduce the incidence of postoperative complications and PHS in elderly patients.

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.

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.

Thymoma with ganglioneuroblastomatous component: case report.

A mediastinal tumor in a 49-year-old woman with myasthenia gravis is reported. The tumor was well-demarcated and located in the supero-anterior mediastinum. Microscopically, the tumor consisted of thymic and neuroblastic tumor components, the latter of which consisted of immature and maturing neuronal cells, abundant neuropils, and Schwannian stroma. The two components intermingled with each other inside the tumor capsule. The tumor was diagnosed as thymoma with a ganglioneuroblastomatous component. The coexistence of epithelial and neuronal tissues in the thymic neoplasm is extremely rare.

DEAD-box RNA helicase subunits of the Drosha complex are required for processing of rRNA and a subset of microRNAs.

MicroRNAs (miRNAs) control cell proliferation, differentiation and fate through modulation of gene expression by partially base-pairing with target mRNA sequences. Drosha is an RNase III enzyme that is the catalytic subunit of a large complex that cleaves pri-miRNAs with distinct structures into pre-miRNAs. Here, we show that both the p68 and p72 DEAD-box RNA helicase subunits in the mouse Drosha complex are indispensable for survival in mice, and both are required for primary miRNA and rRNA processing. Gene disruption of either p68 or p72 in mice resulted in early lethality, and in both p68(-/-) and p72(-/-) embryos, expression levels of a set of, but not all, miRNAs and 5.8S rRNA were significantly lowered. In p72(-/-) MEF cells, expression of p72, but not a mutant lacking ATPase activity, restored the impaired expression of miRNAs and 5.8S rRNA. Furthermore, we purified the large complex of mouse Drosha and showed it could generate pre-miRNA and 5.8S rRNA in vitro. Thus, we suggest that DEAD-box RNA helicase subunits are required for recognition of a subset of primary miRNAs in mDrosha-mediated processing.

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.