Detection of EGFR mutations in circulating free DNA by PNA-mediated PCR clamping.
BACKGROUND
Epidermal growth factor receptor (EGFR)-activating mutations are major determinants in predicting the tumor response to EGFR tyrosine kinase inhibitors in non-small cell lung cancer (NSCLC). Noninvasive test for the detection of EGFR mutations is required, especially in NSCLC patients from whom tissue is not available. In this study, we assessed the feasibility of detection of EGFR mutations in free DNA circulating in plasma.


METHODS
Plasma samples of 60 patients with partial response to gefitinib were analyzed to detect EGFR-activating mutations in exons 19 and 21. Forty (66.7%) of patients had tumor EGFR mutation results. EGFR mutations in plasma were detected using the peptide nucleic acid (PNA)-mediated polymerase chain reaction (PCR) clamping method. All clinical data and plasma samples were obtained from 11 centers of the Korean Molecular Lung Cancer Group (KMLCG).


RESULTS
Of the 60 patients, 39 were female and the median age was 62.5 years. Forty-three patients never smoked, 53 had adenocarcinomas, and seven had other histologic types. EGFR-activating mutation was detected in plasma of 10 cases (exon 19 deletion in seven and exon 21 L858R point mutation in three). It could not be found in plasma after treatment for 2 months. When only patients with confirmed EGFR mutation in tumor were analyzed, 17% (6 of 35) of them showed positive plasma EGFR mutation and the mutation type was completely matched with that in tumor. There was no statistically significant difference in clinical parameters between patients with EGFR mutations in plasma and those without EGFR mutations.


CONCLUSIONS
The detection rate of EGFR mutations from plasma was not so high despite highly sensitive EGFR mutation test suggesting that more advances in detection methods and further exploration of characteristics of circulating free DNA are required.
Hye-Ryoun
HR
Kim
Sung Yong
SY
Lee
Dae-Sung
DS
Hyun
Min Ki
MK
Lee
Hyun-Kyung
HK
Lee
Chang-Min
CM
Choi
Sei-Hoon
SH
Yang
Young-Chul
YC
Kim
Yong Chul
YC
Lee
Sun Young
SY
Kim
Seung Hun
SH
Jang
Jae Cheol
JC
Lee
Kye Young
KY
Lee
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000097:blood / Q000201:enzymology / Q000235:genetics* / Q000473:pathology; D004252:DNA Mutational Analysis; D004273:DNA, Neoplasm / Q000097:blood / Q000235:genetics*; D066246:ErbB Receptors / Q000097:blood / Q000235:genetics*; D005091:Exons; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000097:blood / Q000201:enzymology / Q000235:genetics* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009154:Mutation; D011446:Prospective Studies; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods
D004273:DNA, Neoplasm; C512478:EGFR protein, human; D066246:ErbB Receptors