Identifying EGFR mutations from SCLC patient plasma by mutant-enriched liquidchip technology.

BACKGROUND: Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKI) such as erlotinib and gefitinib are targeted drugs for the kinase domain of EGFR. They are widely used for the treatment of non-small cell lung cancer (NSCLC). The EGFR exon 19 deletion mutation and the L858R mutation in exon 21 comprise approximately 90% of the somatic mutations in NSCLC patients that respond to EGFR TKI. Several recent studies have also reported that small cell lung cancer (SCLC) patients with EGFR mutations responded to gefitinib. Further study, however, has been limited due to the difficulty obtaining tumor specimens from SCLC patients. OBJECTIVES: The aim of this study was to explore the EGFR mutation status in SCLC patients by plasma analysis. MATERIAL AND METHODS: Plasma samples from SCLC patients were collected for mutant-enriched liquidchip (MEL) analysis to identify the EGFR mutations in exon 19 and 21. RESULTS: The exon 19 deletion mutation was detected in one out of 35 patients (a female non-smoker). No exon 21 mutations were found. CONCLUSIONS: A prevalence of EGFR mutations in SCLC is rare, and occurs most frequently in females and nonsmokers.

Expression and mutation of the c-kit gene and correlation with prognosis of small cell lung cancer.

Small cell lung cancer (SCLC) is a highly aggressive and lethal type of cancer in humans. SCLC is sensitive to chemotherapy and radiotherapy, but long-term survival is low and the majority of patients eventually develop progressive disease. With the success of imatinib mesylate in the treatment of gastrointestinal stromal tumors expressing c-kit, its use in SCLC serves as a novel molecular therapeutic approach. The activity of imatinib mesylate is correlated with the mutation of c-kit gene exons 9 and 11 in gastrointestinal stromal tumors. The incidence of epidermal growth factor receptor mutation in non-small cell lung cancer is higher in China than in the United States of America and European countries. There may be also differences in the incidence of c-kit mutation between China and European countries. At present, no study examining imatinib mesylate treatment for SCLC in China is available. To investigate the expression and mutation of c-kit and the correlation with prognosis of SCLC in China, immunohistochemistry was used to detect the expression of c-kit, and a pyrosequencing assay was used to detect mutations in c-kit exons 9 and 11 of 36 SCLC patients who received surgical treatment at the Zhejiang Cancer Hospital, Hangzhou, China, between 1998 and 2010. All 36 patients were followed up to analyze the correlation between prognosis and expression and mutation of c-kit. The incidence of c-kit-positive expression was 83.3%, including 25.0% weak staining, 22.2% moderate staining and 36.1% strong staining. The overall survival of patients with c-kit strong staining was shorter compared to patients with c-kit not strong staining. No mutation in c-kit exons 9 and 11 was detected. In conclusion, the findings showed that the expression of c-kit is high, and strong staining is a prognostic factor for worse survival.