Epidermal Growth Factor Receptor Gene in Primary Tumor and Metastatic Sites from Non-small Cell Lung Cancer

Intracerebral infusion of the bispecific targeted toxin DTATEGF in a mouse xenograft model of a human metastatic non-small cell lung cancer

The aim of this study is to investigate the anti-cancer effect of the bispecific diphtheria toxin (DT) based immunotoxin DTATEGF, which targets both the epidermal growth factor (EGF) receptor (EGFR) and the urokinase-type plasminogen activator (uPA) receptor (uPAR) in vitro and in vivo when delivered by convection-enhanced delivery (CED) via an osmotic minipump in a human metastatic non-small cell lung cancer (NSCLC) brain tumor mouse xenograft model. The effects of the bispecific immunotoxin DTATEGF, and monospecific DTAT, DTEGF and control DT at various concentrations were tested for their ability to inhibit the proliferation of human metastatic NSCLC PC9-BrM3 cells in vitro by MTT assay. A xenograft model of human metastatic NSCLC intracranial model was established in nude mice using the human NSCLC PC9-BrM3 cell line genetically marked with a firefly luciferase reporter gene. One microgram of DTATEGF in the treatment group or control DT in the control group was delivered intracranially by CED via an osmotic minipump. The bioluminescent imaging (BLI) was performed at day 7, 14, 1 month, 2 months, and 3 months. Kaplan-Meier survival curves for the two groups were generated. The brain tissue samples were stained by hematoxylin and eosin for histopathological assessment. In vitro, DTATEGF could selectively kill PC9-BrM3 cells and showed an IC(50) less than 0.001 nM, representing a more than 100- to 1000-fold increase in activity as compared to monospecific DTAT and DTEGF. In vivo, mice with tumors were treated intracranially with drug via CED where the results showed the treatment was successful in providing a survival benefit with the median survival of mice treated with DTATEGF being significantly prolonged relative to controls (87 vs. 63 days, P = 0.006). The results of these experiments indicate that DTATEGF kills the NSCLC PC9-BrM3 cell line in vitro, and when it is delivered via CED intracranially, it is highly efficacious against metastatic NSCLC brain tumors. DTATEGF is a safe and effective drug where further preclinical and clinical development is warranted for the management of metastatic brain tumors.

EGFR mutations, gene amplification, and protein expression and KRAS mutations in primary and metastatic tumors of nonsmall cell lung cancers and their clinical implications: a meta-analysis

A meta-analysis was performed to determine EGFR mutations, gene amplification, and protein expression and KRAS mutations in primary and metastatic nonsmall cell lung cancer (NSCLC). We found that KRAS gene mutation frequencies were higher in primary than in metastatic tumors. There was no significant difference in EGFR mutation frequency between the primary and metastatic tumors. These results suggest that KRAS mutations in primary NSCLC foci may be a more accurate biomarker than in metastases to reflect KRAS mutation status. Combined detection of EGFR and KRAS mutations in primary NSCLC foci appears to be an optimal approach for first-line EGFR-TKI therapy.

EGFR and KRAS quality assurance schemes in pathology: generating normative data for molecular predictive marker analysis in targeted therapy

INTRODUCTION

The aim of this study was to compare the reproducibility of epidermal growth factor receptor (EGFR) immunohistochemistry (IHC), EGFR gene amplification analysis, and EGFR and KRAS mutation analysis among different laboratories performing routine diagnostic analyses in pathology in The Netherlands, and to generate normative data.

METHODS

In 2008, IHC, in-situ hybridisation (ISH) for EGFR, and mutation analysis for EGFR and KRAS were tested. Tissue microarray sections were distributed for IHC and ISH, and tissue sections and isolated DNA with known mutations were distributed for mutation analysis. In 2009, ISH and mutation analysis were evaluated. False-negative and false-positive results were defined as different from the consensus, and sensitivity and specificity were estimated.

RESULTS

In 2008, eight laboratories participated in the IHC ring study. In only 4/17 cases (23%) a consensus score of ≥75% was reached, indicating that this analysis was not sufficiently reliable to be applied in clinical practice. For EGFR ISH, and EGFR and KRAS mutation analysis, an interpretable result (success rate) was obtained in ≥97% of the cases, with mean sensitivity ≥96% and specificity ≥95%. For small sample proficiency testing, a norm was established defining outlier laboratories with unsatisfactory performance.

CONCLUSIONS

The result of EGFR IHC is not a suitable criterion for reliably selecting patients for anti-EGFR treatment. In contrast, molecular diagnostic methods for EGFR and KRAS mutation detection and EGFR ISH may be reliably performed with high accuracy, allowing treatment decisions for lung cancer.

Synchronous lung cancers: when same histological types feature different molecular profiles and response phenotypes

We discuss the case of synchronous bilateral lung cancers which feature the same histological phenotype and a different EGFR mutational profile. Both histological and molecular characterizations were performed on specimens derived thorough CT-guided fine needle aspiration. A first-line chemotherapy was unsuccessful. Subsequent objective response to the EGFR inhibitor Erlotinib was clearly coherent with the sequencing data and the mutated nodule was effectively reduced (> 50%) after therapy, while the lesion assessed as EGFR wild type featured a slight response. This report has two relevant implications. It points out that in case of multiple malignant lesions at time of diagnosis, molecular profiling should be as extensive as possible and it might contribute to clarify the association between the lesions found. Besides the molecular analysis on cytology specimens could identify an accurate and safe diagnostic approach for clinical use.

EGFR and KRAS mutations and altered c-Met gene copy numbers in primary non-small cell lung cancer and associated stage N2 lymph node-metastasis

This study aimed to detect mutations in EGFR and KRAS and alterations of c-Met gene copy number (GCN) changes in primary and lymph node-metastatic NSCLCs. The data showed the concordant rate of EGFR genotype in primary and stage N2 lymph node-metastatic tumors was 95.45%. c-Met GCN in stage N2 lymph nodes was significantly higher than that of the primary tumors (P=0.038). The results suggest both primary and lymph-node metastases have relatively consistent EGFR mutations and EGFR mutations are not relevant to changes in c-Met GCN. c-Met GCN was increased significantly in EGFR TKI-naive patients with lymph node-metastatic tumors.

EGFR gene status in cytological samples of nonsmall cell lung carcinoma: controversies and opportunities

BACKGROUND

In nonsmall cell lung cancer (NSCLC), the development and clinical application of tyrosine kinase inhibitors (TKIs) targeting the epidermal growth factor receptor (EGFR) has required the investigation of EGFR status by gene copy number and/or mutation analysis. This review aimed to present the current knowledge of the use of cytological specimens for EGFR testing in lung cancer.

METHODS

A systematic computerized search was performed of the MEDLINE(R) and EMBASE databases to identify articles reporting the use of cytological samples for determining EGFR status in NSCLC.

RESULTS

Data were extracted from 30 original articles. An additional 19 reviews, consensus statements, and editorials were selected from 175 retrieved papers. Different techniques using cell blocks, scraped cells from archival slides, and fresh cells have shown promising results and include fluorescent in situ hybridization (FISH), direct sequencing, and quantitative polymerase chain reaction (PCR), with similar or higher accuracy and sensitivity than surgical specimens. Preservation and quality of the extracted DNA seem to matter more than the actual number of tumor cells present in the samples. However, major issues still reside in the amount of material, the interference from background non-neoplastic cells, and standardization of parameters for cytological samples.

CONCLUSIONS

This analysis provided evidence that cytological material is suitable for detecting EGFR status using several different methodologies and preparations. New prospective, clinical studies are encouraged for collection and handling of cytological samples as well as for validation of novel techniques in large cohorts.

[Comparison of EGFR and KRAS status between primary non-small cell lung cancer and corresponding metastases: a systematic review and meta-analysis]

BACKGROUND AND OBJECTIVE

Epidermal growth factor receptor (EGFR) and KRAS status were particularly critical for the choice of first-line targeted therapy of non-small cell lung cancer (NSCLC), while the primary tumor and metastases might be different in the EGFR and KRAS gene status. The aim of this pooled analysis is to compare EGFR and KRAS status in matching primary NSCLC and metastases and further to guide clinical practice.

METHODS

Systematic computerized searches of the Pubmed and Medline databases (up to May 10, 2010) meeting specified search criteria were performed, followed by a further screening according to inclusive and exclusive criteria.

RESULTS

Fourteen articles were selected into the final meta-analysis with paired primary and metastatic cases of 598. Expression level of EGFR protein and mutation frequency of KRAS gene in primary tumors were higher than that in metastases, relative risk (RR)=1.13 (95%CI: 0.98-1.31, P=0.09) and RR=1.39 (95%CI: 0.95-2.03, P=0.09), respectively. EGFR gene copy number in metastases was higher than that in primary tumor, RR=0.74 (95%CI: 0.53-1.02, P=0.06). There was no statistically significant difference of EGFR mutation frequency in primary tumors and metastases (P=0.31). The discordant rate in primary and metastases was 17.09% for EGFR mutation, 27.07% for EGFR amplification, 27.84% for EGFR protein expression and 25.91% for KRAS mutation.

CONCLUSIONS

The systematic analysis showed that the EGFR mutation status in primary lung cancer and corresponding metastases was more stable than KRAS gene. KRAS mutation in primary lung cancerous foci seems to better reflect systemically cancerous genetic characteristics of KRAS gene. Determination of KRAS gene status based merely on metastatic foci might lead to more resistant selections of EGFR tyrosine kinase inhibitor (TKI) therapy. Combined detection of EGFR and KRAS mutation from primary NSCLC foci might serve as a better predictive biomarker for anti-EGFR targeted therapy.

EML4-ALK fusion gene assessment using metastatic lymph node samples obtained by endobronchial ultrasound-guided transbronchial needle aspiration

PURPOSE

Anaplastic lymphoma kinase (ALK) fusion genes represent novel oncogenes for non-small cell lung cancers (NSCLC). Several ALK inhibitors have been developed, and are now being evaluated in ALK-positive NSCLC. The feasibility of detecting ALK fusion genes in samples obtained by endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) was determined. The clinicopathologic characteristics of ALK-positive lung cancer were also analyzed.

EXPERIMENTAL DESIGN

From April 2008 to July 2009, NSCLC cases with hilar/mediastinal lymph node metastases detected by EBUS-TBNA were enrolled. Positive expression of ALK fusion protein was determined using immunohistochemistry, and ALK gene rearrangements were further examined to verify the translocation between ALK and partner genes using fluorescent in situ hybridization and reverse transcription-PCR. Direct sequencing of PCR products was performed to identify ALK fusion variants.

RESULTS

One hundred and nine cases were eligible for the analysis using re-sliced samples. Screening of these specimens with immunohistochemistry revealed ALK positivity in seven cases (6.4%), all of which possessed echinoderm microtubule-associated protein-like 4-ALK fusion genes as detected by fluorescent in situ hybridization and reverse transcription-PCR. All ALK-positive cases had an adenocarcinoma histology and possessed no EGFR mutations. Compared with ALK-negative cases, ALK-positive cases were more likely to have smaller primary tumors (P < 0.05), to occur at a younger age (<60 years; P < 0.05), and to occur in never/light smokers (smoking index < 400; P < 0.01). Mucin production was frequently observed in ALK-positive adenocarcinomas (29.4%; P < 0.01).

CONCLUSIONS

EBUS-TBNA is a practical and feasible method for obtaining tissue from mediastinal and hilar lymph nodes that can be subjected to multimodal analysis of ALK fusion genes in NSCLC.

Initial evaluation of the nonsmall cell lung cancer patient: diagnosis and staging

PURPOSE OF REVIEW

The initial diagnosis and staging of nonsmall cell lung cancer patients is complex and involves multiple technologies. This review evaluates the recent literature and integrates it into a systematic method for evaluating patients.

RECENT FINDINGS

The goal of the initial diagnosis and staging of nonsmall cell lung cancer is to provide sufficient information to allow definitive treatment. Initial steps should include a history and physical, basic laboratory tests, pulmonary functions, and PET-computed tomography (CT) imaging. If there is evidence of metastatic disease, then biopsy of the most advanced lesion is warranted. If there is no evidence of metastatic disease, the evaluation should focus on evaluation of the mediastinal lymph nodes. If there is evidence of nodal involvement by PET-CT, then endobronchial ultrasound-guided transbronchial needle aspiration is warranted. If there is no evidence of nodal involvement on PET-CT, then either surgery or CT-guided fine needle aspiration is warranted. Other factors that should be kept in mind when selecting a diagnostic strategy include whether or not the patient is a surgical candidate, the impact of comorbidities, the type of cancer, the need for predictive biomarker analysis, and the range of possible treatment options.

SUMMARY

Integrating new technologies such as PET-CT and endobronchial ultrasound into the initial evaluation of patients can save unnecessary diagnostic procedures and lead to more rapid and accurate staging.