Echinoderm Microtubule-associated Protein-like 4-anaplastic Lymphoma Kinase Fusion Research Articles

Recurrence of Lung Adenocarcinoma After an Interval of 15 Years Revealed by Demonstration of the Same Type of EML4–ALK Fusion Gene

We carried out an experiment on a 58-year-old man with multiple left lung tumors and swelling of multiple lymph nodes. For clinical staging and therapeutic purposes, bronchoalveolar lavage (BAL) cytology and lung biopsy were performed. The biopsy specimen revealed the left lower lung mass to be immunohistochemically ALK (anaplastic lymphoma kinase)-positive adenocarcinoma. Using the BAL specimen from the left lower lung, EML4 (echinoderm microtubule-associated protein-like 4)-ALK variant 1 fusion gene was detected by reverse transcription-polymerase chain reaction (RT-PCR). His past history showed that he had undergone an operation for lung adenocarcinoma of the right lower lobe 15 years before, and the pathological specimen at that time revealed that the lung adenocarcinoma with pleural invasion and single metastasis of mediastinal lymph node showed a mucinous cribriform pattern and/or signet-ring cell pattern. The typical histology led us to examine the ALK rearrangement in the primary lung cancer and mediastinal metastatic tumor. Immunohistochemistry (IHC) for ALK was positive, and ALK break apart fluorescence in situ hybridization (FISH) showed a positive result. Moreover, RT-PCR using formalin-fixed, paraffin-embedded tissue from the right lung cancer also demonstrated EML4–ALK variant 1 fusion gene. Although there is a possibility that the left lung cancer is de novo one with multiple metastases, detection of the same fusion gene of the very rare EML4–ALK variant 1 in both tumors suggests that the left cancer is a recurrence of the right lung cancer after an interval of 15 years.

Serum carcinoembryonic antigen levels before initial treatment are associated with EGFR mutations and EML4- ALK fusion gene in lung adenocarcinoma patients.

Epidermal growth factor receptor (EGFR) mutations and echinoderm microtubule associated protein like 4-anaplastic lymphoma kinase (EML4-ALK) define specific molecular subsets of lung adenocarcinomas with distinct clinical features. Our purpose was to analyze clinical features and prognostic value of EGFR gene mutations and the EML4-ALK fusion gene in lung adenocarcinoma. EGFR gene mutations and the EML4-ALK fusion gene were detected in 92 lung adenocarcinoma patients in China. Tumor marker levels before first treatment were measured by electrochemiluminescence immunoassay. EGFR mutations were found in 40.2% (37/92) of lung adenocarcinoma patients, being identified at high frequencies in never-smokers (48.3% vs. 26.5% in smokers; P=0.040) and in patients with abnormal serum carcinoembryonic antigen (CEA) levels before the initial treatment (58.3% vs. 28.6%, P=0.004). Multivariate analysis revealed that a higher serum CEA level before the initial treatment was independently associated with EGFR gene mutations (95%CI: 1.476~11.343, P=0.007). We also identified 8 patients who harbored the EML4-ALK fusion gene (8.7%, 8/92). In concordance with previous reports, younger age was a clinical feature for these (P=0.008). Seven of the positive cases were never smokers, and no coexistence with EGFR mutation was discovered. In addition, the frequency of the EML4-ALK fusion gene among patients with a serum CEA concentration below 5 ng/ml seemed to be higher than patients with a concentration over 5 ng/ml (P=0.021). No significant difference was observed for time to progression and overall survival between EML4-ALK-positive group and EML4-ALK-negative group or between patients with and without an EGFR mutation. The serum CEA level before the initial treatment may be helpful in screening population for EGFR mutations or EML4-ALK fusion gene presence in lung adenocarcinoma patients.

Analysis of clinicopathological features of the echinoderm microtubule-associated protein-like-4-anaplastic lymphoma kinase fusion gene in Chinese patients with advanced non-small-cell lung cancer.

The echinoderm microtubule-associated protein-like-4-anaplastic lymphoma kinase (EML4-ALK) fusion gene defines a novel molecular subset of non-small-cell lung cancer (NSCLC). However, the clinicopathological features of patients with the EML4-ALK fusion gene have not been defined completely. Clinicopathological data of 200 Chinese patients with advanced NSCLC were analyzed retrospectively to explore their possible correlations with EML4-ALK fusions. The EML4-ALK fusion gene was detected in 56 (28.0%) of the 200 NSCLC patients, and undetected in 22 (11.0%) patients because of an insufficient amount of pathological tissue. The median age of the patients with positive and negative EML4-ALK was 48 and 55 years, respectively. Patients with the EML4-ALK fusion gene were significantly younger (P< 0.001). The detection rate of the EML4-ALK fusion gene in patients who received primary tumor or metastatic lymph node resection was significantly higher than in patients who received fine-needle biopsy (P= 0.003). The detection rate of the EML4-ALK fusion gene in patients with a time lag from obtainment of the pathological tissue to EML4-ALK fusion gene detection ≤48 months was significantly higher than in patients >48 months (P= 0.020). The occurrence of the EML4-ALK fusion gene in patients with wild-type epidermal growth factor receptor (EGFR) was significantly higher than in patients with mutant-type EGFR (42.5% [37/87] vs. 6.3% [1/16], P= 0.005). Younger age and wild-type EGFR were identified as clinicopathological characteristics of patients with advanced NSCLC who harbored the EML4-ALK fusion gene. The optimal time lag from the obtainment of the pathological tissue to the time of EML4-ALK fusion gene detection is ≤48 months.

Comparison of IHC, FISH and RT-PCR Methods for Detection of ALK Rearrangements in 312 Non-Small Cell Lung Cancer Patients in Taiwan

BackgroundRecently Echinoderm microtubule-associated protein-like 4- anaplastic lymphoma kinase (EML4-ALK) fusion gene has become an important biomarker for ALK tyrosine kinase inhibitor (crizotinib) treatment in NSCLC. However, the best detection method and the significance of EML4-ALK variant types remain uncertain.MethodsReverse transcriptase-polymerase chain reaction (RT-PCR), fluorescence in Situ hybridization (FISH) and Immunohistochemical (IHC) stain were performed on tumor tissues of 312 NSCLC patients for detection of ALK rearrangements. Mutation analyses for EGFR and KRAS genes were also performed.ResultsThirteen of the 312 patients (4.17%) had ALK rearrangements detected by RT-PCR. If RT-PCR data was used as the gold standard, FISH tests had a low sensitivity (58.33%), but very good specificity (99.32%). IHC stain had better sensitivity (91.67%) than FISH, but lower specificity (79.52%), when the cut off was IHC2+. All of the 8 patients with high abundance of EML4-ALK positive cells in tumor tissues (assessed by the signal intensities of the RT-PCR product), were also have high expression of ALK protein (IHC3+), and positive for FISH, except one failed in FISH. Variants 3a+3b (4/5, 80%) of EML4-ALK fusion gene were more common to have high abundance of EML4-ALK positive cells in tumor tissues than variant 1 (1/3, 33.3%). Meta-analysis of the published data of 2273 NSCLC patients revealed that variant 3 (23/44, 52.3%) was the most common type in Chinese population, while variant 1 (28/37, 75.7%) was most common in Caucasian.ConclusionsAmong the three detection methods, RT-PCR could detect not only the presence of EML4-ALK fusion gene and their variant types, but also the abundance of EML4-ALK positive cells in NSCLC tumor tissues. The latter two factors might affect the treatment response to anti-ALK inhibitor. Including RT-PCR as a diagnostic test for ALK inhibitor treatment in the prospective clinical trials is recommended.

Analysis of EGFR, EML4-ALK, KRAS, and c-MET mutations in Chinese lung adenocarcinoma patients

ABSTRACTIntroduction: Mutation analysis of cancer driver genes is helpful for determining an optimal treatment strategy. We evaluated mutations in four driver genes, namely epidermal growth factor receptor (EGFR), Kirsten ras oncogene (KRAS), c-MET, and echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase (EML4-ALK), in Chinese lung adenocarcinoma patients from Hunan Province. Methods: We enrolled 110 lung adenocarcinoma patients in a single institution. EGFR and KRAS mutations were examined by direct sequencing, the EML4-ALK fusion gene was analyzed by fluorescence in situ hybridization, and c-MET amplification and c-Met protein expression were detected by quantitative PCR and immunohistochemistry, respectively. Results: EGFR and KRAS mutations were observed in 52.7% (58/110) and 3.6% (4/106) of patients, respectively. c-MET amplification was detected in 5.5% (6/110) of patients. In addition, 30% (33/110) of the cases expressed c-Met protein, including all of the patients harboring c-MET amplification. Ten percent (11/110) of patients harbored the EML4-ALK fusion gene, and the frequency of ALK rearrangement was higher than that of other cohort analyses involving patients from other regions in China. Almost all of these gene mutations were exclusive except that in two female non-smoking patients, who harbored an EGFR mutation and EML4-ALK rearrangement simultaneously. In total, 70% of patients in the study harbored one of the four gene mutations. Conclusions: Most Chinese lung adenocarcinoma patients harbor driver gene mutations, among which ALK rearrangements were more common in Hunan patients than in previously reported populations. Future clinical trials should be conducted to determine the safety and efficacy of drug combination targeting different driver mutations.

Detection of ALK Rearrangement by Immunohistochemistry in Lung Adenocarcinoma and the Identification of a Novel EML4-ALK Variant

The echinoderm microtubule-associated protein-like 4 anaplastic lymphoma kinase (EML4-ALK) fusion gene has been identified as a potent oncogenic driver in non-small-cell lung cancer, in particular adenocarcinoma (ADC). It defines a unique subgroup of lung ADC, which may be responsive to ALK inhibitors. Detection of ALK rearrangement by fluorescence in situ hybridization (FISH) or reverse transcriptase polymerase chain reaction (RT-PCR) is considered to be the standard procedure, but each with its own limitation. We evaluated the practical usefulness of immunohistochemistry (IHC) to detect ALK expression as a reliable detection method of ALK rearrangement in lung ADC. We tested 373 lung ADCs for ALK rearrangement by IHC and FISH. Multiplex RT-PCR was performed to confirm the fusion variants. Twenty-two of 373 lung ACs (5.9%) were positive for ALK immunoreactivity. ALK-positive tumor cells demonstrated strong and diffused granular staining in the cytoplasm. All the ALK IHC-positive cases were confirmed to harbor ALK rearrangement, either by FISH, or RT-PCR. Two cases with positive ALK protein expression, but negative for breakapart FISH signal were shown to harbor EML4-ALK variant 1 by RT-PCR. None of the ALK IHC-negative cases were FISH-positive. In addition, we identified a novel EML4-ALK fusion variant (E3:ins53A20), and its potent transformation potential has been confirmed by in vivo tumorigenicity assay. IHC can effectively detect ALK rearrangement in lung cancer. It might provide a reliable and cost-effective diagnostic approach in routine pathologic laboratories for the identification of suitable candidates for ALK-targeted therapy.

A case of lung adenocarcinoma harboring exon 19 EGFR deletion and EML4-ALK fusion gene

We report a man with advanced adenocarcinoma who harboring exon 19 (E746-A750del) epidermal growth factor receptor (EGFR) deletion and echinoderm microtubule-associated protein like 4-anaplastic lymphoma kinase (EML4-ALK) gene translocation in the re-biospy specimen. The patient was treated with erlotinib with a stable disease but progressed slowly, while crizotinib showed a complete response.

Anaplastic lymphoma kinase gene rearrangement and non-small cell lung cancer management: a step forward in personalized therapy

Dear Editor, We greatly enjoyed reading the thought-provoking article by Lopes et al. in a recent issue of your esteemed journal (1). Interestingly, in recent years, data have emerged regarding a role for EML4 (echinoderm microtubule-associated protein-like 4)–ALK (anaplastic lymphoma kinase) in personalized treatment for advanced non-small-cell lung cancer (NSCLC) (2,3). EML4-ALK undergoes constitutive dimerization through the interaction between the coil-coil domains within the EML4 region of each monomer, thereby activating ALK and promoting oncogenic activity (4). EML4-ALK fusion, EGFR, and KRAS mutations are all mutually exclusive, implicating ALK rearrangement as a potential therapeutic target in EGFR wild-type and KRAS wild-type lung cancers (5). Nevertheless, Lopes' study (1) raises some interesting questions. Was patient selection for the study carried out appropriately? Did the study provide a representative sample of the Latin-American population, as described in the paper? Could immunohistochemistry be substituted for fluorescence in situ hybridization? Which technique is more appropriate for clinical practice? Should we perform this analysis in a specific subset of patients or in all advanced NSCLC patients? In addition, it is interesting to speculate whether EML4-ALK-targeted therapies may be relevant for clinicians, although patients positive for the EML4–ALK fusion protein frequently present at an advanced clinical stage, and their tumors demonstrate a solid adenocarcinoma pattern and signet ring cells (5). Furthermore, the presence of the EML4-ALK fusion oncoprotein is associated with nonsmokers or light smokers and is more frequent in younger patients (5). Thus, young, non-smoking patients and patients with adenocarcinoma tumor histology may indeed benefit from an EML4-ALK diagnostic test. Recently, the U.S. Food and Drug Administration approved crizotinib, which is a small-molecule inhibitor of the ALK tyrosine kinase, as a treatment for patients with locally advanced or metastatic NSCLC expressing the EML4–ALK fusion protein (2). The results were recently reported for a clinical trial in which 82 ALK-positive patients were evaluated for the therapeutic efficacy of crizotinib (6). The results were quite promising, demonstrating an overall response rate of 57% (46 partial responses and 1 complete response) and a 33% stable disease rate (27 patients) (2). Of the 82 patients, 63 (77%) continued to receive crizotinib at the time of data cut off, and the estimated probability of a 6-month progression-free survival was 72% (2). Thus, the refined understanding of the NSCLC molecular profile described over the last decade has proven to be an important tool to help medical oncologists develop new approaches for NSCLC treatment. Despite the small frequency of advanced NSCLC patients who present with EML4-ALK fusion (2.4 to 6.7%) (1), we believe that all patients in this setting should have the opportunity to receive such innovative therapies and approaches. However, further studies are warranted to establish the appropriate pharmaco-economic profiles.

Membrane Phospholipids, EML4-ALK, and Hsp90 as Novel Targets in Lung Cancer Treatment

Approximately one third of patients with non-small cell lung cancer have unresectable stage IIIA or stage IIIB disease; combined cytotoxic chemotherapy and radiation therapy delivered concurrently has been established as the standard treatment for such patients. Despite many clinical trials that tested several different radiochemotherapy combinations, it seems that a plateau of efficiencies at the acceptable risk of complications has been reached. Clinical studies indicate that the improved efficacy of radiochemotherapy is associated with the radiosensitizing effects of chemotherapy. Improvement of outcomes of this combined modality by developing novel radiosensitizers is a viable therapeutic strategy. In addition to causing cell death, ionizing radiation also induces a many-faceted signaling response, which activates numerous prosurvival pathways that lead to enhanced proliferation in the endothelial cells and increased vascularization in tumors. Radiation at doses used in the clinic activates cytoplasmic phospholipase A2, leading to increased production of arachidonic acid and lysophosphatidylcholine. The former is the initial step in the generation of eicosanoids, while the later is the initial step in the formation of lysophosphatidic acid, leading to the activation of inflammatory pathways. The echinoderm microtubule-associated protein-like 4 anaplastic lymphoma kinase (EML4-ALK) is member of the insulin superfamily of receptor tyrosine kinases. The EML4-ALK fusion gene appears unique to lung cancer and signals through extracellular signal regulated kinase and phosphoinositide 3-kinase. Heat shock protein 90 (Hsp90) is often overexpressed and present in an activated multichaperone complex in cancer cells, and it is now regarded as essential for malignant transformation and progression. In this review we focus on radiosensitizing strategies involving the targeting of membrane phospholipids, EML4-ALK, and Hsp90 with specific inhibitors and briefly discuss the combination of radiation with antivascular agents.

Comparison of Reverse Transcription-Polymerase Chain Reaction, Immunohistochemistry, and Fluorescence In Situ Hybridization Methodologies for Detection of Echinoderm Microtubule-Associated Proteinlike 4–Anaplastic Lymphoma Kinase Fusion–Positive Non–Small Cell Lung Carcinoma: Implications for Optimal Clinical Testing

Echinoderm microtubule-associated proteinlike 4-anaplastic lymphoma kinase (EML4-ALK) gene fusions are detected in 3% to 13% of non-small cell lung carcinomas. Accurate testing for detection of EML4-ALK fusions is essential for appropriate therapy selection. To compare reverse transcription-polymerase chain reaction (RT-PCR), immunohistochemistry (IHC), and fluorescence in situ hybridization (FISH) methodologies for detection of EML4-ALK fusions. Forty-six pulmonary adenocarcinomas were selected with enrichment for wild-type epidermal growth factor receptor (EGFR) status (wild type, n = 42; mutant, n = 4). Specimens were tested by IHC (Dako; clone ALK1), FISH (Abbott Molecular; LSI ALK break apart), and RT-PCR (variants 1 and 3a/b). EML4-ALK variant 3a/b was detectable by RT-PCR, FISH, and IHC in 4% (2 of 46) of specimens. Complete agreement among FISH and IHC reviewers was obtained for variant 3a/b. No concordance existed among methodologies for the detection of EML4-ALK variant 1. The RT-PCR method detected variant 1 in 20% (9 of 46) of specimens. Agreement among FISH viewers was poor for variant 1 because only 11% (1/9) of specimens were scored as positive by all 3 viewers. The sensitivity of IHC for detection of variant 1 was also poor because only 1 of 9 samples (11%) was scored as positive. Overall, the frequency of EML4-ALK variants 1 and 3a/b was 24% (11 of 46) in adenocarcinomas enriched for wild-type EGFR status. One EML4-ALK variant 1 fusion was found to coexist with an EGFR exon 21 mutation. The FISH interpretation demonstrated great variability among observers. The RT-PCR method was the most sensitive and least-subjective methodology for detection of EML4-ALK fusions.

EML4-ALK Translocation Predicts Better Outcome in Lung Adenocarcinoma Patients with Wild-Type EGFR

The echinoderm microtubule-associated protein like 4-anaplastic lymphoma kinase (EML4-ALK) fusion represents a novel target in a subset of non-small cell lung cancer, especially adenocarcinoma. EML4-ALK fusion is mutually exclusive with epidermal growth factor receptor (EGFR) mutations. To understand the impact of EML4-ALK on the prognosis of non-small cell lung cancer, we examined EML4-ALK fusion in lung adenocarcinoma from patients with wild-type EGFR and analyzed their clinical treatment outcomes. Lung adenocarcinoma patients with malignant pleural effusions having wild-type EGFR and measurable target lesions were enrolled for EML4-ALK analysis by reverse transcription-polymerase chain reaction and direct sequencing. Demographic data, EML4-ALK status, and survival data were analyzed. We also performed fluorescence in situ hybridization on some available tumor samples to validate the PCR result. In addition, K-ras mutation was analyzed for patients without EML4-ALK fusion genes. A total of 116 patients with wild-type EGFR sequencing results had complete clinical data for analysis. No patients received ALK inhibitor therapy. There were 39 patients (34%) with the EML4-ALK fusion gene. The concordance rate between reverse transcription-polymerase chain reaction and fluorescence in situ hybridization was 85%. The K-ras mutation rate for patients without EML4-ALK fusion gene was 6.5%. By multivariate analysis, patients who had better performance status (p < 0.001) and EML4-ALK translocation (p = 0.017) had longer overall survival. Comparing patients with tumors harboring variant 1 with those harboring nonvariant 1 EML4-ALK fusion genes, there were no significant differences in clinical factors and survival outcome. For lung adenocarcinoma patients with wild-type EGFR, EML4-ALK translocation is associated with longer overall survival.

Correlation of anaplastic lymphoma kinase overexpression and the EML4-ALK fusion gene in non-small cell lung cancer by immunohistochemical study

Recently the echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase (EML4-ALK) fusion gene with transforming activity was identified in non-small cell lung cancer (NSCLC). In addition, NSCLC patients with the EML4-ALK fusion gene had a dramatic response and longer progression free survival after ALK inhibitor treatment than those without this fusion gene. However, the incidence and clinical and molecular characteristics of the EML4-ALK fusion gene in NSCLC patients of Taiwan are still unclear. Sixty-four fresh frozen tumor specimens were obtained from the tissue bank of Chang Gung Memorial Hospital for RNA extraction and EML4-ALK fusion gene detection. Paraffin sections of lung tumors from all of these patients were available and were analyzed for ALK protein expression by immunohistochemical (IHC) study. The results were correlated with clinical and molecular biomarkers. Three of the 64 tumors (4.7%) had the EML4-ALK fusion gene. Two were adenocarcinomas, and one was adenosquamous carcinoma. Twenty patients with non-squamous cell carcinomas had epidermal growth factor receptor (EGFR) mutations, so the EML4-ALK fusion gene was found in 14.3% of EGFR wild type non-squamous cell carcinomas. Two tumors were variant 3 (3a+3b with 3b predominant) and had strong staining (3+) for ALK by IHC stains. One tumor was variant 1 and had moderate staining (2+) for ALK. None of the ALK wild type tumors had strong staining for ALK. When compared with other clinical and molecular features, only the IHC stain for ALK was significantly correlated with the EML4-ALK fusion gene (p = 0.0002). ALK overexpression detected by IHC study could be a promising detection method for the EML4-ALK fusion gene and is worth further confirmation with more samples.

Research progress in non-small cell lung cancer with concomitant EML4-ALK fusion gene and EGFR gene mutation

肺癌是最常见的恶性肿瘤之一，其中非小细胞肺癌（non-small cell lung cancer, NSCLC）占肺癌的80%-85%。分子靶向治疗是目前NSCLC最热门也是最具前景的领域之一，其中的热点分子包括表皮生长因子受体（epidermal growth factor receptor, EGFR）、棘皮动物微管样蛋白4-间变淋巴瘤激酶（echinoderm microtubule associated protein like4-anaplastic lymphoma kinase, EML4-ALK）等。既往研究认为EML4-ALK融合基因与EGFR突变不能共存。近期陆续报道了EML4-ALK融合基因与EGFR突变共存的病例。本文就EML4-ALK融合基因及EGFR突变基因的分子结构、发生率和目前已报道双突变患者的临床特点等进行综述。

Bright-Field Dual-Color Chromogenic In Situ Hybridization for Diagnosing Echinoderm Microtubule-Associated Protein-Like 4-Anaplastic Lymphoma Kinase-Positive Lung Adenocarcinomas

A subset of lung cancers harbors an EML4-ALK (echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase) gene fusion, and detecting this subset may hold therapeutic implications. Many prior studies used fluorescence in situ hybridization (FISH) analysis for this detection, but FISH may have disadvantages including signal decay and dark-field examination that may obscure tissue architecture. In this study, we explored the potential of the ALK-break-apart chromogenic in situ hybridization (CISH) method to detect ALK-rearranged lung cancer. We examined 15 lung adenocarcinomas with reverse-transcriptase polymerase chain reaction-proven EML4-ALK fusion transcripts and 30 ALK-negative cases. One hundred tumor cells were evaluated by CISH and FISH for each case, and a detailed signal profile was recorded and compared. CISH preserved tissue architecture and cytomorphology considerably and facilitated the signal evaluation using a routine light microscope. Positive rearrangement signals (splits or isolated 3' signals) were identified in 13 to 78% (mean ± SD, 41% ± 19%) of tumor cells in the ALK-positive cohort and in 0 to 15% (mean ± SD, 6% ± 4%) of cells in the ALK-negative cohort. The two groups were best separated by a cutoff value of 20%, with a sensitivity of 93% and a specificity of 100%. The only false-negative tumor having only 13% CISH-positive cells displayed predominantly (76%) isolated 5' signals unaccompanied by 3' signals. FISH showed largely similar signal profiles, and the results were completely concordant with CISH. We have successfully introduced CISH for diagnosing EML4-ALK-positive lung adenocarcinoma. This method allows simultaneous visualization of genetics and tumor cytomorphology and facilitates the molecular evaluation and could be applicable in clinical practice to detect lung cancer that may be responsive to ALK inhibitors.

Exon scanning by reverse transcriptase–polymerase chain reaction for detection of known and novel EML4–ALK fusion variants in non–small cell lung cancer

Chromosomal inversions within chromosome 2p, resulting in fusions between the echinoderm microtubule-associated protein-like 4 (EML4) and anaplastic lymphoma kinase (ALK) genes, are a recent focus of treatment options for non-small cell lung cancer. Thirteen EML4-ALK fusion variants have been identified, affecting eight EML4 exons. We have developed an exon scanning approach using multiplex reverse transcriptase-polymerase chain reaction (RT-PCR) to amplify known and potential variants involving the first 22 EML4 exons. A total of 55 formalin-fixed, paraffin-embedded lung cancer tumors were screened, of which 5 (9%) were positive for EML4-ALK fusions. Four positive cases harbored known fusion variants: variant 3a, 3b, or both in three cases and variant 1 in one case. The fifth positive specimen harbored two novel variants, designated 8a and 8b, involving exon 17 of EML4. Fluorescence in situ hybridization confirmed the presence of EML4-ALK fusions in three of the four RT-PCR-positive specimens with sufficient tissue for examination, and also confirmed absence of fusions in all 19 RT-PCR-negative specimens tested. Immunohistochemistry analysis confirmed ALK protein expression in the sample containing the novel 8a and 8b variants. This RT-PCR-based exon scanning approach avoids the limitations of screening only for previously identified EML4-ALK fusions and provides a simple molecular assay for fusion detection in a clinical diagnostics setting.

Evaluation of EML4-ALK Fusion Proteins in Non–Small Cell Lung Cancer Using Small Molecule Inhibitors

The echinoderm microtubule–associated protein-like 4–anaplastic lymphoma kinase (EML4-ALK) fusion gene resulting from an inversion within chromosome 2p occurs in approximately 5% of non–small cell lung cancer and is mu-tually exclusive with Ras and EGFR mutations. In this study, we have used a potent and selective ALK small molecule inhibitor, NPV-TAE684, to assess the oncogenic role of EML4-ALK in non–small cell lung cancer (NSCLC). We show here that TAE684 inhibits proliferation and induces cell cycle arrest, apoptosis, and tumor regression in two NSCLC models that harbor EML4-ALK fusions. TAE684 inhibits EML4-ALK activation and its downstream signaling including ERK, AKT, and STAT3. We used microarray analysis to carry out targeted pathway studies of gene expression changes in H2228 NSCLC xenograft model after TAE684 treatment and identified a gene signature of EML4-ALK inhibition. The gene signature represents 1210 known human genes, and the top biologic processes represented by these genes are cell cycle, DNA synthesis, cell proliferation, and cell death. We also compared the effect of TAE684 with PF2341066, a c-Met and ALK small molecule inhibitor currently in clinical trial in cancers harboring ALK fusions, and demonstrated that TAE684 is a much more potent inhibitor of EML4-ALK. Our data demonstrate that EML4-ALK plays an important role in the pathogenesis of a subset of NSCLC and provides insight into the mech-anism of EML4-ALK inhibition by a small molecule inhibitor.

A novel RT-PCR approach to detecting EML4-ALK fusion genes in archival NSCLC tissue.

10535 Background: The echinoderm microtubule-associated protein-like 4–anaplastic lymphoma kinase (EML4-ALK) fusion gene can be detected in subsets of NSCLC, especially never-smoking patients with adenocarcinoma, and appears to be mutually exclusive of EGFR mutation. PF-1066, a potent and selective c-MET/ALK inhibitor, yields high response rates in ALK-positive patients, as detected by labor-intensive fluorescent in situ hybridization (FISH) methodology. Existing RT-PCR assays for these gene variants are designed to amplify large cDNA fragments (> 450 bases), while formalin-fixed paraffin-embedded (FFPE) specimens yield mostly RNA fragments of < 150 bases. Thus, our goal was to design a robust RT-PCR assay for EML4-ALK fusion gene transcripts suitable for use with commonly available FFPE tissues of limited size. Methods: Synthetic fragments representing the nine EML4-ALK fusion genes variants 1, 2, 3a, 3b, 4, 5a, 5b, 6 and 7 were generated by recursive PCR technology. The approach consisted of amplifying over-lapping fragments containing the fusion variant sequences with outside 5′ and 3′ primers. Primer probes were designed to detect specific EML4-ALK fusion gene fragments with a maximum amplicon of 170 bases by RT-PCR. Results: Functional RT-PCR assay were developed for each specific EML4-ALK variant, meeting criteria specified above for optimal clinical testing. Assays detecting multiple fusion variants without distinguishing specific variants were also designed. All nine known EML4-ALK variants can be detected using 6 RT-PCR assays. Screening of NSCLC cDNAs from the Response Genetics database is underway (molecular and clinical correlations to be presented). Conclusions: We developed RT-PCR assays capable of detecting EML4-ALK fusion gene variants from FFPE tissues. Two assays were successfully established: one that can detect and identify each individual variant, and one capable of detecting the presence of any variant as a single assay. We expect this methodology to provide a useful tool for large-scale screening of NSCLC or other FFPE tissues for the EML4-ALK fusion gene. Author Disclosure Employment or Leadership Position Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Response Genetics Amgen, AstraZeneca, Biodesix, Boehringer Ingelheim, Bristol-Myers Squibb, Genentech, GlaxoSmithKline, Lilly, Merck, Novartis, Pfizer, sanofi-aventis Response Genetics DxS Abbott Laboratories, Bristol-Myers Squibb, Genentech, Lilly, Merck, Novartis, Pfizer

Clinicopathologic Features of Non-Small-Cell Lung Cancer with EML4–ALK Fusion Gene

A fusion gene between echinoderm microtubule-associated protein-like 4 (EML4) and the anaplastic lymphoma kinase (ALK) has recently been identified in nonsmall-cell lung cancers (NSCLCs). We screened for EML4-ALK fusion genes and examined the clinicopathological and genetic characteristics of fusion-harboring NSCLC tumors. We examined 313 NSCLC samples from patients who underwent resection at our hospital between May 2001 and July 2005. We screened for the fusion genes using reverse-transcription polymerase chain reaction (RT-PCR) assay and confirmed the results with direct sequencing. We also examined mutations in the epidermal growth factor receptor (EGFR), KRAS, and ERBB2 genes. Five EML4-ALK fusion genes were detected (four from 111 female samples and one from 202 male samples; 1.6% overall). All five genes were found in adenocarcinomas and accounted for 2.4% of the 211 adenocarcinoma samples. One EML4-ALK fusion was variant 1, and two were variant 3. In addition, we also found two new fusion variants. Patients with fusion-positive tumors were nonsmokers or light smokers. Among the 211 adenocarcinomas, mutations in EGFR, KRAS, and ERBB2 were detected in 105, 29, and 7 tumors, respectively. Interestingly, all of the fusion-positive NSCLCs had no mutations within these genes. EML4-ALK fusion genes were observed predominantly in adenocarcinomas, in female or nonsmoking populations. Additionally, the EML4-ALK fusions were mutually exclusive with mutations in the EGFR, KRAS, and ERBB2 genes.

Exon Array Profiling Detects EML4-ALK Fusion in Breast, Colorectal, and Non–Small Cell Lung Cancers

The echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase (EML4-ALK) fusion gene has been identified as an oncogene in a subset of non-small cell lung cancers (NSCLC). We used profiling of cancer genomes on an exon array to develop a novel computational method for the global search of gene rearrangements. This approach led to the detection of EML4-ALK fusion in breast and colorectal carcinomas in addition to NSCLC. Screening of a large collection of patient tumor samples showed the presence of EML4-ALK fusion in 2.4% of breast (5 of 209), 2.4% of colorectal (2 of 83), and in 11.3% of NSCLC (12 of 106). Besides previously known EML4-ALK variants 1 (E13; A20) and 2 (E20; A20), a novel variant E21; A20 was found in colorectal carcinoma. The presence of an EML-ALK rearrangement was verified by identifying genomic fusion points in tumor samples representative of breast, colon, and NSCLC. EML4-ALK translocation was also confirmed by fluorescence in situ hybridization assay, which revealed its substantial heterogeneity in both primary tumors and tumor-derived cell lines. To elucidate the functional significance of EML4-ALK, we examined the growth of cell lines harboring the fusion following EML4 and ALK silencing by small interfering RNA. Significant growth inhibition was observed in some but not all cell lines, suggesting their variable dependence on ALK-mediated cell survival signaling. Collectively, these findings show the recurrence of EML4-ALK fusion in multiple solid tumors and further substantiate its role in tumorigenesis.

The EML4‐ALK fusion gene is involved in various histologic types of lung cancers from nonsmokers with wild‐type EGFR and KRAS

The echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase (EML4-ALK) fusion gene resulting from the chromosome inversion inv(2)(p21;p23) recently was identified in nonsmall cell lung cancer (NSCLC). The authors of this study investigated the frequency, genetic and clinicopathologic profiles of EML4-ALK in Chinese patients with NSCLC. EML4-ALK was investigated in 266 resected primary NSCLC, including adenocarcinomas (AD), lymphoepithelioma-like carcinomas, squamous cell carcinomas, mucoepidermoid carcinomas, and adenosquamous carcinomas, by reverse transcriptase-polymerase chain reaction and was verified by sequencing. EML4-ALK protein expression was studied by immunohistochemistry. Thirteen tumors (4.9%) had EML4-ALK comprising 4 fusion transcript variants with fusion of the variable segments from 5' EML4 to 3' ALK and with preservation of the ALK kinase domain. The most common variant consisted of 8 tumors with variant 3 that involved EML4 exon 6. The others included 2 tumors with variant 1 (exon 13), 2 tumors with variant 2 (exon 20), and 1 tumor with the novel variant 5 (exon 18). There were 11 ADs and 2 unusual carcinomas with mixed squamous and glandular components. Immunohistochemistry demonstrated diffuse ALK fusion proteins in the tumor cell cytoplasm. EML4-ALK was associated with nonsmokers (P = .009). Tumors with the fusion gene had the wild-type epidermal growth factor receptor (EGFR) (P = .001) and v-Ki-ras2/Kirsten rat sarcoma viral oncogene homolog (KRAS) genes. Patients who had EML4-ALK-positive AD had a younger median age (P = .018) compared with patients who did not have the fusion gene. The EML4-ALK fusion gene was present in various histologic types of NSCLC. It occurred in mutual exclusion to EGFR and KRAS mutations and was associated with nonsmokers. The authors concluded that EML4-ALK may be useful for predicting the potential response to ALK inhibitors as a therapeutic option for patients with lung cancer.