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RFLP Found EGFR Mutations Quickly in NSCLC Patients Treated With Gefitinib

RFLP Found EGFR Mutations Quickly in NSCLC Patients Treated With Gefitinib

TOKYO, Japan-Using restriction fraction length polymorphisms (RFLP) looks promising as a quick and cost-effective method of screening tumor specimens for epidermal growth factor receptor (EGFR) mutations, say researchers who compared this method with direct sequencing. RFLP identified the same mutations as direct sequencing in 73 tissue samples, said Ichiro Kawada, MD, of the Keio University School of Medicine in Tokyo, who presented the findings (abstract 7071). "This was basically a methodologic study sending the message that there are other ways besides sequencing to quickly measure the presence of EGFR mutations," said Roman Perez-Soler, MD, chief of the oncology division at Montefiore Medical Center in New York, in discussing the trial. Direct sequencing, currently the only method used to verify existence of EGFR mutations, is time-consum-ing and expensive, the investigators pointed out. Now that EGFR mutations have been linked to response to tyrosine kinase inhibitors in lung cancer, screening for mutations is emerging as an important step in selecting treatment and in clinical trial protocols. To use RFLP, the investigators first extracted RNA from tumor specimens of 73 patients with non-small-cell lung cancer (NSCLC) who had been treated with gefitinib. They then made cDNA, then performed PCR on the cDNA using three pairs of originalprimers designed for RFLP to detect mutations. The PCR products were digested with corresponding enzymes. Before and after digestion, the PCR products were run on a 2% agarose gel and the existence of mutations was assessed. All specimens were also directly sequenced before digestion to identify mutations. Both RFLP and direct sequencing found the same mutations: 19% of specimens had deletion mutations in exon 19; 11% had point mutations in exon 21, codon 858; and 1% had point mutations in exon 18, codon 719. The researchers also found that the mutations were closely associated with response to gefitinib. Eight of the nine patients who responded had mutations and none of those who did not respond had mutations. Dr. Kawada and colleagues concluded that RFLPdetected mutations may be useful in predicting the sensitivity of NSCLC patients to gefitinib.

 
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