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We found a significant association between EGFR mutation and risk of brain metastases at the time of diagnosis and follow-up after curative resection for pulmonary adenocarcinoma. This result indicates the distinct clinical features of EGFR-mutated tumors in terms of brain metastases.

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A B S T R A C T PurposeThis trial was conducted to determine the optimal duration of chemotherapy in Korean patients with advanced non-small-cell lung cancer (NSCLC). Patients and MethodsPatients with stages IIIB to IV NSCLC who had not progressed after two cycles of chemotherapy were randomly assigned to receive either four (arm A) or two (arm B) more cycles of third-generation, platinum-doublet treatment. ResultsOf the 452 enrolled patients, 314 were randomly assigned to the groups. One-year survival rates were 59.0% in arm A and 62.4% in arm B, and the difference of 3.4% (95% CI, Ϫ8.0 to 4.8) met the predefined criteria for noninferiority. The median time to progression (TTP), however, was 6.2 months (95% CI, 5.7 to 6.7 months) in arm A and 4.6 months (95% CI, 4.4 to 4.8 months) in arm B, the difference of which is statistically significant (P ϭ .001). The frequencies of hematologic and nonhematologic toxicities were similar in the two arms. ConclusionThis study confirms the noninferiority of overall survival with four cycles compared with six cycles of chemotherapy for the first-line treatment of advanced NSCLC and supports the current American Society of Clinical Oncology guidelines. Notably, patients receiving six cycles of chemotherapy compared with four cycles showed a favorable TTP, suggesting that further investigation of the new strategies of maintenance therapy with less toxic agents after three to four cycles of induction chemotherapy might be warranted to improve survival, with consideration of both ethnicity and pharmacogenomic signatures.

A marine bacterium, designated strain GW14-5T, capable of degrading high-molecular-mass polycyclic aromatic hydrocarbons was isolated from the sediments of Gwangyang Bay, Republic of Korea, after enrichment culture for 2 years with a mixture of benzo[a]pyrene and pyrene. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the isolate forms a phyletic lineage that is distinct from the seven known orders within the ‘Alphaproteobacteria’. 16S rRNA gene sequence similarity of strain GW14-5T to all recognized bacterial species was not greater than 92 %. The dominant fatty acids of the isolate were i-17 : 1 (46·2 %), i-15 : 0 (15·1 %) and i-17 : 0 (12·6 %). The major respiratory quinone was MK-5, and the DNA G+C content was 39·3 mol%. Cells of strain GW14-5T were Gram-negative, motile, catalase-positive, oxidase-positive and weakly halophilic. Glucose, N-acetylglucosamine and maltose were utilized as sole carbon sources. The strain was positive for β-glucosidase activity. Optimal growth of strain GW14-5T was at pH 7·0 and 37–40 °C and required the presence of 2 % (w/v) NaCl. On the basis of this evidence, strain GW14-5T represents a novel genus and species in the ‘Alphaproteobacteria’ for which the name Kordiimonas gwangyangensis gen. nov., sp. nov. is proposed. The novel order Kordiimonadales is proposed for the distinct phyletic line represented by the genus Kordiimonas. The type strain is GW14-5T (=KCCM 42021T=JCM 12864T).

Treatment with gefitinib, a specific inhibitor of epidermal growth factor receptor tyrosine kinase (EGFR-TK), has resulted in dramatic responses in some patients with nonsmall cell lung cancer (NSCLC). Most patients who respond to gefitinib have EGFR-TK mutations; however, >10% of patients with EGFR-TK mutations do not respond. Similarly, some patients without EGFR-TK mutations respond to this drug, suggesting that other factors determine sensitivity to gefitinib. Aberrations of the tumor suppressor gene p53 are frequently associated with drug resistance. In this study, we investigated the role of p53 in growth-inhibitory and apoptotic effects of gefitinib in the human NSCLC cell lines NCI-H1299 and A549, which have no EGFR-TK mutations. NCI-H1299 cells, which had a p53-null genotype, were more resistant to gefitinib compared with A549 cells, which were wild-type p53 (IC 50 , 40 Mmol/L in NCI-H1299 and 5 Mmol/L in A549). Treatment of A549 with gefitinib resulted in the translocation of p53 from cytosol to nucleus and the up-regulation of Fas, which was localized to the plasma membrane. In the stable H1299 cell line with tetracycline-inducible p53 expression, induced p53 enhanced growth inhibition and apoptosis by gefitinib through the up-regulation of Fas and restoration of caspase activation. A caspase inhibitor, Z-VAD-fmk, reduced these effects. Conversely, inhibition of p53 using antisense oligonucleotide in A549 caused a significant decrease in apoptosis by gefitinib and down-regulation of Fas under the same conditions. In conclusion, p53 may play a role in determining gefitinib sensitivity by regulating Fas expression in NSCLC.

The development of resistance to epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKI) seems almost inevitable, even in patients with lung cancer that initially respond well to EGFR-TKIs. MET amplification was recently found to be a mechanism of escape from the anticancer effect of EGFR inhibitors. In the present study, we investigated the means whereby MET affects sensitivity to EGFR-TKIs in PC-9 cells. Gefitinib-or erlotinib-resistant sublines were established by exposing the parental PC-9 cell line to chronic, repeated treatments with these drugs. These resistant sublines showed more than 100-fold more resistance to gefitinib and erlotinib and acquired cross-resistance to other EGFR-TKIs. The T790M EGFR mutation was found by pyrosequencing, and this seemed to be the cause of drug resistance. Resistant cells also showed MET activation, although gene amplification was not detected. Furthermore, the induction of MET activity was not found to be associated with sensitivity to EGFR-TKIs. Interestingly, increased passage number without exposure to gefitinib or erlotinib caused MET activation, but this did not affect sensitivity to EGFR-TKIs. In addition, hepatocyte growth factor was found to block the ability of EGFR-TKIs to inhibit MET activation. However, sustained MET activation by hepatocyte growth factor did not modulate the cellular effects of gefitinib or erlotinib. Rather, activated MET enhanced migration and invasion abilities. Summarizing, MET activation may be acquired during cancer cell proliferation and enhances migratory and invasive abilities without affecting cellular sensitivity to EGFR-TKIs. Accordingly, the present study suggests that MET activation caused by factors other than MET gene amplification is not a suitable surrogate marker of resistance to EGFR-TKIs.