PCR-based testing for therapy-related EGFR mutations in patients with non-small cell lung cancer.

BACKGROUND: In patients with non-small cell lung cancer (NSCLC), mutations in the epidermal growth factor receptor gene (EGFR) have been associated with improved response to tyrosine kinase inhibitors. Two hotspot mutations located in exon 19 and exon 21 account for about 90% of all EGFR mutations.
MATERIALS AND METHODS: We designed a Bi-PASA (bidirectional PCR amplification of specific alleles) assay to detect the most common exon 19 deletion (codons 746-750) and an allele-specific PCR for the L858R mutation in exon 21. To validate the assays for use in clinical diagnostics, 35 lung adenocarcinoma samples were analyzed.
RESULTS: Both assays provided the predicted amplification pattern for normal and mutant genotypes with high specificity and sensitivity. In serial dilution experiments, the mutant alleles were detectable in mixed samples with an at least 6-fold excess of normal DNA. Three exon 19 deletions were identified in the tumor samples.
CONCLUSION: Both assays are fast and easy to perform in any routine PCR laboratory with no special equipment other than thermocyclers. They provide sensitive and cost effective initial EGFR testing for identifying lung cancer patients who might clinically benefit from tyrosine kinase inhibitors.