Direct sequencing and amplification refractory mutation system for epidermal growth factor receptor mutations in patients with non-small cell lung cancer.

Treatment with epidermal growth factor receptor (EGFR) tyrosine inhibitors (EGFR-TKIs) provides encouraging outcomes for advanced non-small cell lung cancer (NSCLC) patients with EGFR mutations. Pleural effusion is a common complication of NSCLC. We compared direct DNA sequencing and ADx Amplification Refractory Mutation System (ADx-ARMS) to detect EGFR mutations in malignant pleural effusion samples. We obtained 24 samples from pleural effusion fluid of NSCLC patients. Three common types of EGFR mutations were examined by direct sequencing and ADx-ARMS analysis. The sensitivity of the methods was compared and the relationship between EGFR mutations and response rates of the patients determined. In 14/24 patients, we detected EGFR mutations (58.3%) by ADx-ARMS, and in 10 samples (41.7%) by direct sequencing. In 6 samples, EGFR mutations were on exon 19, and in 8 samples, mutations were on exon 21 by ADx-ARMS. By contrast, we found EGFR mutations in 4 samples on exon 19, and in 6 samples on exon 21 by direct sequencing. Neither method showed mutations on exon 20. Among the 24 patients, there was 83.3% concordance for the methods. In 18/24 patients, gefitinib treatment was administered, including 10 patients with mutations who showed improved response compared to 8 of the wild-type patients (P<0.05). In conclusion, EGFR mutation analysis by ADx-ARMS was the most sensitive compared to direct sequencing, and provided more reliable EGFR mutation assessments. ADx-ARMS could be introduced into the clinical practice to identify NSCLC patients likely to benefit from TKI treatment, especially those with malignant pleural effusion.