Epidermal growth factor receptor mutation analysis in cytological specimens and responsiveness to gefitinib in advanced non-small cell lung cancer patients

Background： Epidermal growth factor receptor（EGFR） mutation is the key predictor of EGFR tyrosine kinase inhibitors（TKIs） efficacy in non-small cell lung cancer（NSCLC）. We conducted this study to verify the feasibility of EGFR mutation analysis in cytological specimens and investigate the responsiveness to gefitinib treatment in patients carrying EGFR mutations.Methods： A total of 210 cytological specimens were collected for EGFR mutation detection by both direct sequencing and amplification refractory mutation system（ARMS）. We analyzed EGFR mutation status by both methods and evaluated the responsiveness to gefitinib treatment in patients harboring EGFR mutations by overall response rate（ORR）, disease control rate（DCR） and progression free survival（PFS）.Results： Of all patients, EGFR mutation rate was 28.6%（60/210） by direct sequencing and 45.2%（95/210） by ARMS（P〈0.001） respectively. Among the EGFR wild type patients tested by direct sequencing, 26.7% of them were positive by ARMS. For the 72 EGFR mutation positive patients treated with gefitinib, the ORR, DCR and median PFS were 69.4%, 90.2% and 9.3 months respectively. The patients whose EGFR mutation status was negative by direct sequencing but positive by ARMS had lower ORR（48.0% vs. 80.9%, P=0.004） and shorter median PFS（7.4 vs. 10.5 months, P=0.009） as compared with that of EGFR mutation positive patients by both detection methods. Conclusions： Our study verified the feasibility of EGFR analysis in cytological specimens in advanced NSCLC. ARMS is more sensitive than direct sequencing in EGFR mutation detection. EGFR Mutation status tested on cytological samples is applicable for predicting the response to gefitinib. Abundance of EGFR mutations might have an influence on TKIs efficacy.

Single Nucleotide Polymorphism Genotyping of Calpastatin Gene Using the ARMS Compared with the RFLP

Calpastatin is an endogenous inhibitor of calpain which is responsible for the breakdown of myofibrillar proteins, The association of Single Nucleotide Polymorphism （SNP） in the calpastatin gene with meat tenderness is an important topic in meat production. Therefore efficient procedure to investigate the SNP is necessary. The objectives of this study were to detect the SNP of calpastatin gene at domain L marker （G/C transversion） of the Kamphaengsaen beef breed （KPS cattle; n = 26） by the Amplification Refractory Mutation System （ARMS） compared with the Restriction Fragment Length Polymorphism （RFLP） methods and to determine the genotypes of the KPS cattle at that marker. Genomic DNA of calpastatin gene extracted from blood of the KPS cattle was detected with ARMS and RFLP methods. The ARMS system has utilized two primer pairs to amplify the two different alleles of a polymorphism in single PCR reaction to detected single base mutation. In this method, the alleles-specific primers had a mismatch at 3＇ terminal base and a second deliberate mismatch at position -2 from 3＇ terminus. While the RFLP method detected a polymorphism using PCR-base technique follow by RsaI restriction enzyme. Amplification of the ARMS method revealed that the results were not different from the conventional method of RFLP. Analysis of genotypes revealed that the KPS cattle inherited the CC, CG and GG genotypes at domain L marker. These were reliable when verified by nucleotide sequence analysis of PCR products. The animals were genotyped and determined for tenderness phenotype with this marker that predicted variation of an intronic polymorphism at domain L of the calpastatin gene. Therefore, the ARMS method was simple, efficient technique, and suitable for detecting SNP at domain L marker of the calpastatin gene.