Clinical significance of the EML4-ALK fusion gene and association with EGFR and KRASgene mutation in 208 Chinese patients with non-small cell lung cancer.

e17514 Background: 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: Genes were detected by nested RT-PCR and confirmed by sequencing. Results: 208 cases of NSCLC were evaluated. There were 24.5% (51/208 cases of mutations in EGFR at exons 18-21, and 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. Conclusions: 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.