Abstract 4589: Clinical significance of the EML4-ALK fusion gene and association with EGFR and KRAS gene mutation in 208 Chinese patients with non-small cell lung cancer

Abstract

Abstract Objective: EML4-ALK fusion gene is a potentially relevant oncogenic event in lung cancer, which represents a new subgroup of non-small cell lung cancer (NSCLC) patients who respond positively to ALK inhibitors. The characteristics of EML4-ALK fusion gene in Chinese Patients with NSCLC are poorly understood. In this study, we aimed to analyze the prevalence of EML4-ALK fusion gene and their correlation to epidermal growth factor receptor (EGFR) status, KRAS mutation, and clinico-pathological data in Chinese patients with NSCLC. Methods: EML4-ALK fusion gene was detected by nested RT-PCR and confirmed by sequencing. EGFR and KRAS gene status were evaluated by RT-PCR and sequencing. Survival analysis was performed. A meta-analysis of the EML4-ALK fusion gene in lung cancer patients was also presented. Results: Two hundred eight NSCLC cases were evaluated. There were 51 cases of mutations in EGFR at exons 18-21 (24.5%, 51/208). Among exons 18-21, EGFR mutations occur predominantly (92%) in exons 19 and 21. In concordance with previous reports, these mutations are identified at high frequencies in females (47.5%, 29/61 vs 15.0%, 22/147 in males; P = 0.000); never-smokers (42.3%, 33/78 vs 13.9%, 18/130 in smokers; P = 0.000), and adenocarcinoma patients (44.2%, 42/95 vs 8.0%, 9/113 in non-adenocarcinoma patients; P = 0.000). There were only 6 cases (6/208, 2.88%) of KRAS mutations in our study group. We identified 7 patients who harbored the EML4-ALK fusion gene (3.37%, 7/208) which all confirmed by DNA sequencing. Of these 7 patients, 2 cases displayed the EML4-ALK variant 1 (28.6%), 1 case exhibited variant 2 (14.3%) and 4 cases carried variant 3 (57.1%). All of the positive cases corresponded to female patients (11.5%, 7/61). Six of the positive cases were non-smokers (7.69%, 6/78). The incidence of EML4-ALK translocation in female non-smoking adenocarcinoma patients is as high as 15.2% (5/33). No EGFR/KRAS mutations were detected among EML4-ALK positive patients. The meta-analysis demonstrated that EML4-ALK translocation was 4.71% (125/2652) in unselected patients with NSCLC, and was also predominant in female patients with adenocarcinoma. Conclusion: EML4-ALK translocations are infrequent in the entire NSCLC patient population, but are frequent in the NSCLC patient subgroup of female, nonsmokers, and adenocarcinoma patients. Our results indicate that the detection of the EML4-ALK translocation in subgroups of patients with NSCLC is crucial for applying targeted therapy. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4589. doi:1538-7445.AM2012-4589