Zhang X, Zhang S, Yang X, et al. Fusion of EML4 and ALK is associated with development of lung adenocarcinomas lacking EGFR and KRAS mutations and is correlated with ALK expression. Mol Cancer. 9:188

Medical Research Center of Guangdong General Hospital, Guangdong Lung Cancer Institute, Guangdong Academy of Medical Sciences, Guangzhou 510080, China.
Molecular Cancer (Impact Factor: 4.26). 07/2010; 9(1):188. DOI: 10.1186/1476-4598-9-188
Source: PubMed


The anaplastic lymphoma kinase (ALK) gene is frequently involved in translocations that lead to gene fusions in a variety of human malignancies, including lymphoma and lung cancer. Fusion partners of ALK include NPM, EML4, TPM3, ATIC, TFG, CARS, and CLTC. Characterization of ALK fusion patterns and their resulting clinicopathological profiles could be of great benefit in better understanding the biology of lung cancer.
RACE-coupled PCR sequencing was used to assess ALK fusions in a cohort of 103 non-small cell lung carcinoma (NSCLC) patients. Within this cohort, the EML4-ALK fusion gene was identified in 12 tumors (11.6%). Further analysis revealed that EML4-ALK was present at a frequency of 16.13% (10/62) in patients with adenocarcinomas, 19.23% (10/52) in never-smokers, and 42.80% (9/21) in patients with adenocarcinomas lacking EGFR and KRAS mutations. The EML4-ALK fusion was associated with non-smokers (P = 0.03), younger age of onset (P = 0.03), and adenocarcinomas without EGFR/KRAS mutations (P = 0.04). A trend towards improved survival was observed for patients with the EML4-ALK fusion, although it was not statistically significant (P = 0.20). Concurrent deletion in EGFR exon 19 and fusion of EML4-ALK was identified for the first time in a Chinese female patient with an adenocarcinoma. Analysis of ALK expression revealed that ALK mRNA levels were higher in tumors positive for the EML-ALK fusion than in negative tumors (normalized intensity of 21.99 vs. 0.45, respectively; P = 0.0018). However, expression of EML4 did not differ between the groups.
The EML4-ALK fusion gene was present at a high frequency in Chinese NSCLC patients, particularly in those with adenocarcinomas lacking EGFR/KRAS mutations. The EML4-ALK fusion appears to be tightly associated with ALK mRNA expression levels. RACE-coupled PCR sequencing is a highly sensitive method that could be used clinically for the identification of EML4-ALK-positive patients.

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Available from: Lucy Yin, Jan 06, 2014
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    • "Specifically, while ALK mRNA is detected in normal adult lung tissues at very low levels, it undergoes dramatic ten-to hundred-fold increase in NSCLCs with ALK rearrangement caused by the much stronger promoter activity of the 5`-fusion partner gene [19] [20] [21] [22] [23]. Importantly, only the 3'-portion (exons 20 to 29) of the ALK mRNA is a part of the rearranged fusion transcript that is detected at high levels, while the presence of the 5`-region (exons 1-19) remains unaffected [19] [20] [21] [22] [23]. "
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    ABSTRACT: Recurrent gene fusions of anaplastic lymphoma receptor tyrosine kinase (ALK) and echinoderm microtubule-associated protein-like 4 (EML4) have been recently identified in ∼5% of non-small cell lung cancers (NSCLCs) and are targets for selective tyrosine kinase inhibitors. While fluorescent in situ hybridization (FISH) is the current gold standard for detection of EML4-ALK rearrangements, several limitations exist including high costs, time-consuming evaluation and somewhat equivocal interpretation of results. In contrast, targeted massive parallel sequencing has been introduced as a powerful method for simultaneous and sensitive detection of multiple somatic mutations even in limited biopsies, and is currently evolving as the method of choice for molecular diagnostic work-up of NSCLCs.
    Full-text · Article · Jun 2014 · Lung cancer (Amsterdam, Netherlands)
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    • "To our knowledge, this is the first report of a concomitant presence of ALK gene rearrangement, EGFR mutation, and KRAS mutation in the same NSCLC patient. Although the vast majority of ALK-positive pulmonary adenocarcinomas lack concomitant EGFR- or KRAS-mutations, suggesting that these mutations are mutually exclusive [4,12,16], single cases with concurrent EML4-ALK fusion gene and EGFR-mutations have been reported [17-20]. These single patients reportedly received EGFR-TKI therapy with variable effect, but none of these patients were treated with crizotinib. "
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    ABSTRACT: Anaplastic lymphoma kinase-positive non-small cell lung carcinoma patients are generally highly responsive to the dual anaplastic lymphoma kinase and MET tyrosine kinase inhibitor crizotinib. However, they eventually acquire resistance to this drug, preventing the anaplastic lymphoma kinase inhibitors from having a prolonged beneficial effect. The molecular mechanisms responsible for crizotinib resistance are beginning to emerge, e.g., in some anaplastic lymphoma kinase-positive non-small cell lung carcinomas the development of secondary mutations in this gene has been described. However, the events behind crizotinib-resistance currently remain largely uncharacterized. Thus, we report on an anaplastic lymphoma kinase-positive non-small cell lung carcinoma patient with concomitant occurrence of epidermal growth factor receptor and V-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog mutations upon development of crizotinib-resistance. A 61-year-old Caucasian never-smoking male was diagnosed with anaplastic lymphoma kinase -positive pulmonary adenocarcinoma, stage T4N3M1b. Treatment with crizotinib initially resulted in complete objective response in the thorax and partial response in the abdomen, but after 8 months of therapy the patient acquired resistance and progressed. Biopsies from new metastases revealed development of epidermal growth factor receptor and V-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog mutations concomitant with the original anaplastic lymphoma kinase gene rearrangement and without signs of anaplastic lymphoma kinase fusion gene amplification or secondary anaplastic lymphoma kinase mutations. To our knowledge, this is the first report of an anaplastic lymphoma kinase-positive pulmonary adenocarcinoma, which upon emergence of crizotinib resistance acquired 2 new somatic mutations in the epidermal growth factor receptor and V-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog genes, respectively, concomitant with the original anaplastic lymphoma kinase rearrangement. Thus, these 3 driver mutations, usually considered mutually exclusive, may coexist in advanced non-small cell lung carcinoma that becomes resistant to crizotinib, presumably because heterogeneous tumor clones utilize epidermal growth factor receptor and/or V-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog signaling to circumvent the inhibition of anaplastic lymphoma kinase-mediated signaling by crizotinib. The identification of new targetable somatic mutations by tumor re-biopsy may help clarify the mechanism behind the development of the acquired crizotinib resistance and pave the way for combined strategies involving multiple targeted therapies.
    Full-text · Article · Nov 2013 · BMC Research Notes
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    • "However, multiple ALK + NSCLC cases that do not fit this clinical stereotype also exist [30] [31]. In relation to molecular pathology profile, ALK rearrangements typically occur independently of EGFR and KRAS gene mutation[14] [28] [32] [33] [34], although these aberrations are not mutually exclusive [14] [34] [35]. In the recent Lung Cancer Mutation Consortium series, 8% of ALK-positive adenocarcinomas were also positive for either an EGFR or KRAS mutation [36]. "
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    ABSTRACT: Pharmacologic agents that target protein products of oncogenes in tumors are playing an increasing clinical role in the treatment of cancer. Currently, the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) represent the standard of care for patients with locally advanced or metastatic non-small cell lung cancer (NSCLC) harboring activating EGFR mutations. Subsequently other genetic abnormalities with "driver" characteristics - implying transforming and tumor maintenance capabilities have been extensively reported in several small distinct subsets of NSCLC. Among these rare genetic changes, anaplastic lymphoma kinase (ALK) gene rearrangements, most often consisting in a chromosome 2 inversion leading to a fusion with the echinoderm microtubule-associated protein like 4 (EML4) gene, results in the abnormal expression and activation of this tyrosine kinase in the cytoplasm of cancer cells. This rearrangement occurs in 2-5% of NSCLC, predominantly in young (50years or younger), never- or former-smokers with adenocarcinoma. This aberration most commonly occurs a independently of EGFR and KRAS gene mutations. A fluorescent in situ hybridization assay was approved by the US Food and Drug Administration (FDA) as the standard method for the detection of ALK gene rearrangement in clinical practice and is considered the gold standard. Crizotinib, a first-in-class dual ALK and c-MET inhibitor, has been shown to be particularly effective against ALK positive NSCLC, showing dramatic and prolonged responses with low toxicity, predominantly restricted to the gastro-intestinal and visual systems, and generally self-limiting or easily managed. However, resistance to crizotinib inevitably emerges. The molecular mechanisms of resistance are currently under investigation, as are therapeutic approaches including crizotinib-based combination therapy and novel agents such as Hsp90 inhibitors. This review aims to present the current knowledge on this fusion gene, the clinic-pathological profile of ALK rearranged NSCLC, and to review the existing literature on ALK inhibitors, focusing on their role in the treatment of NSCLC.
    Full-text · Article · Aug 2013 · Cancer Treatment Reviews
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