EGFR Mutation status in Japanese lung cancer patients: genotyping analysis using LightCycler.
OBJECTIVE
Recently, somatic mutations of the epidermal growth factor receptor (EGFR) gene were found in approximately 25% of Japanese lung cancer patients. These EGFR mutations are reported to be correlated with clinical response to gefitinib therapy. However, DNA sequencing using the PCR methods described to date is time-consuming and requires significant quantities of DNA; thus, this existing approach is not suitable for a routine pretherapeutic screening program.


METHODS
We have genotyped EGFR mutation status in Japanese lung cancer patients, including 102 surgically treated lung cancer cases from Nagoya City University Hospital and 16 gefitinib-treated lung cancer cases from Kinki-chuo Chest Medical Center. The presence or absence of three common EGFR mutations were analyzed by real-time quantitative PCR with mutation-specific sensor and anchor probes.


RESULTS
In exon 21, EGFR mutations (CTG --> CGG; L858R) were found from 8 of 102 patients from Nagoya and 1 of 16 from Kinki. We also detected the deletion mutations in exon 19 from 7 of 102 patients from Nagoya (all were deletion type 1a) and 4 of 16 patients from Kinki (one was type 1a and three were type 1b). In exon 18, one example of G719S mutation was found from both Nagoya and Kinki. The L858R mutation was significantly correlated with gender (women versus men, P < 0.0001), Brinkman index (600 < or = versus 600, P = 0.001), pathologic subtypes (adenocarcinoma versus nonadenocarcinoma, P = 0.007), and differentiation status of the lung cancers (well versus moderately or poorly, P = 0.0439), whereas the deletion mutants were not. EGFR gene status, including the type of EGFR somatic mutation, was correlated with sensitivity to gefitinib therapy. For example, some of our gefitinib-responsive patients had L858R or deletion type 1a mutations. On the other hand, one of our gefitinib-resistant patients had a G719S mutation.


CONCLUSIONS
Using the LightCycler PCR assay, the EGFR L858R mutation status might correlate with gender, pathologic subtypes, and gefitinib sensitivity of lung cancers. However, further genotyping studies are needed to confirm the mechanisms of EGFR mutations for the sensitivity or resistance of gefitinib therapy for the lung cancer.
Sasaki
Hidefumi
H
Department of Surgery II, Nagoya City University Medical School, Nagoya, Japan. hisasaki@med.nagoya-cu.ac.jp
Endo
Katsuhiko
K
Konishi
Akimitsu
A
Takada
Minoru
M
Kawahara
Masaaki
M
Iuchi
Keiji
K
Matsumura
Akihide
A
Okumura
Meinoshin
M
Tanaka
Hisaichi
H
Kawaguchi
Tomoya
T
Shimizu
Toshiki
T
Takeuchi
Hiroshi
H
Yano
Motoki
M
Fukai
Ichiro
I
Fujii
Yoshitaka
Y
D000230:Adenocarcinoma / Q000188:drug therapy / Q000235:genetics / Q000601:surgery; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000483:Alleles; D000970:Antineoplastic Agents / Q000627:therapeutic use; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy / Q000235:genetics / Q000601:surgery; D004252:DNA Mutational Analysis / Q000295:instrumentation*; D004273:DNA, Neoplasm / Q000737:chemistry / Q000235:genetics; D066246:ErbB Receptors / Q000235:genetics*; D005260:Female; D000077156:Gefitinib; D005787:Gene Frequency; D005838:Genotype; D006801:Humans; D007564:Japan; D008175:Lung Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D009154:Mutation; D020125:Mutation, Missense; D016133:Polymerase Chain Reaction / Q000379:methods; D011799:Quinazolines / Q000627:therapeutic use
D000970:Antineoplastic Agents; D004273:DNA, Neoplasm; D011799:Quinazolines; D066246:ErbB Receptors; D000077156:Gefitinib