Naoto Kitahara

EGFR R497K polymorphism is a favorable prognostic factor for advanced lung cancer

IntroductionIt has been reported that the R497K polymorphism of the epidermal growth factor receptor (EGFR) gene has attenuated functions in ligand binding, tyrosine kinase activation, and growth stimulation. On other hand, EGFR gene mutations at kinase domain in non-small cell lung cancer (NSCLC) have been examined for their ability to predict sensitivity to gefitinib or erlotinib.Materials and methodsWe investigated the EGFR mutations and/or R497K polymorphism statuses in 225 surgically treated NSCLC cases. 192 adenocarcinoma cases were included. The presence or absence of EGFR polymorphism of exon 13 was analyzed by PCR–RFLP method.ResultsEGFR mutations at kinase domain were found from 95 of 225 lung cancer patients. In 86.2% of patients, homo- or heterozygous Lys497 allele was present. No correlation existed between R497K EGFR genotype and clinico-pathological features, such as gender, smoking status, and pathological subtypes.ConclusionsEGFR mutation status was not correlated with R497KEGFR genotype of lung cancers. In node-negative patients, R497KEGFR genotype was not correlated with disease outcome. In node-positive patients, however, R497K EGFR was significantly associated with better overall survival. This association was attributable to neo-adjuvant or adjuvant chemotherapy. In 46 total gefitinib treated NSCLC patients, the prognosis was not different between the EGFR wild type (GG) patients and AG+AA patients. R497KEGFR polymorphism might be associated with favorable prognosis of advanced lung cancers and correlated with chemosensitivity.

EGFR Polymorphism of the Kinase Domain in Japanese Lung Cancer

BACKGROUND Mutations of the epidermal growth factor receptor (EGFR) gene at kinase domain have been reported in non-small-cell lung cancer (NSCLC), and some common somatic mutations in EGFR have been examined for their ability to predict sensitivity to gefitinib or erlotinib. However, EGFR mutations at exon 20 have been reported to predict resistance to gefitinib therapy. MATERIALS AND METHODS We investigated the EGFR mutations and/or polymorphism statuses at kinase domain in 303 surgically treated non-small cell lung cancer (NSCLC) cases. One hundred ninety-four adenocarcinoma cases were included. The presence or absence of EGFR polymorphism of kinase domains was analyzed by direct sequences. We have also investigated EGFR polymorphism status at exon 20 for 23 NSCLC patients who had undergone surgery followed by treatment with gefitinib at the National Hospital Organization, Kinki-chuo Chest Medical Center. RESULTS EGFR mutations at kinase domain were found in 75 of 303 lung cancer patients. During sequencing of EGFR tyrosine kinase domain in tumors, 86 EGFR polymorphism (G2607A) cases were identified at exon 20. G2067A polymorphism was significantly higher in nonadenocarcinomas (37.4%) than in adenocarcinoma (25.3%, P = 0.0415). The polymorphism status did not correlate with gender, smoking (never smoker versus smoker), and EGFR mutations. In 46 total gefitinib treated NSCLC patients, there was a tendency toward better prognosis in EGFR wild type (GG) patients than AG + AA patients. EGFR polymorphism in Japanese lung cancers seemed to be less frequent than Caucasian lung cancers. CONCLUSIONS EGFR-tyrosine kinase polymorphism might be associated with clinicopathological background of lung cancers.

Polymorphisms in intron 1 of the EGFR gene in non‑small cell lung cancer patients

The epidermal growth factor receptor (EGFR) gene is highly polymorphic and its expression and activity may be affected by various polymorphisms. There have been several studies examining associations between EGFR polymorphisms and clinical outcome of lung cancer therapy; however, the underlying mechanism is largely unknown. The present study investigated EGFR polymorphism status and its correlation with clinicopathological features in Japanese non-small cell lung cancer (NSCLC) patients. We investigated 5 polymorphisms in the EGFR gene (−216G/T, −191C/A, 8227G/A, D994D and R497K) in 274 surgically-treated NSCLC patients. TaqMan single nucleotide polymorphism (SNP) genotyping assays and a PCR-based assay were used to analyze these polymorphisms. In our cohort of patients we did not find any evidence of the −191C/A polymorphism. Our results showed that the patients with the 8227GA or AA type in intron 1 had a significantly better prognosis with the anti-EGFR therapy than the patients with the GG type (p=0.0448) in terms of recurrence of lung cancer. No significant association was observed between 3 other SNPs (−216G/T, D994D and R497K) and clinicopathological features. The EGFR 8227G/A polymorphism in intron 1 may be associated with clinical outcome in NSCLC patients treated with EGFR tyrosine kinase inhibitors.