Published papers

Biapenem has been widely used to treat bacterial pneumonia; however, there is little information concerning its efficacy and safety in elderly patients. Based on pharmacokinetic-pharmacodynamic theory, administration of biapenem thrice rather than twice daily would be expected to be more effective because of longer time above the minimum inhibitory concentration. In this study, we aimed to evaluate the efficacy, safety, and pharmacokinetics of biapenem (300 mg) administered thrice daily in pneumonic patients aged 65 years or older. Biapenem was effective in 22 of 25 patients, as assessed by the improvement in clinical symptoms and/or the eradication of the causative organisms, and caused no serious adverse events. The pharmacokinetic profile was established based on simulations using a modeling program. Among 17 patients whose causative organisms were detected, time above the minimum inhibitory concentration was estimated to be 100% in 16 patients, all of whom showed clinical improvement. The results of this study confirmed the efficacy and safety of 300 mg of biapenem administered thrice daily for the treatment of pneumonia in elderly patients. © 2014, Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

Objectives: We previously reported low expression of miR-375 in squamous-cell carcinoma (SCC) and high expression in adenocarcinoma (AC) of the lung. miR-. 375's target genes and its function in non-small-cell lung cancer (NSCLC) have not been elucidated. Therefore, the present study was designed to identify the targets of miR-375 and to characterize its function in NSCLC. Materials and methods: Candidate targets of miR-375 were determined using a prediction database and previous data on differential gene expression between SCC and AC. We evaluated miR-375 and target-gene expression levels in 12 NSCLC cell lines. The effect of miR-375 overexpression and knockdown was evaluated in NSCLC cell lines by transfecting them with an miR-375 precursor or inhibitor. A luciferase-reporter assay was performed to confirm a direct interaction between miR-375 and its target gene. Further, a wound-healing assay was performed to evaluate the effect of miR-375 overexpression on the migration of SK-MES-1 cells. Finally, to assess the clinical relevance, 63 clinical NSCLC samples were analyzed. Results: Claudin-1 (CLDN1) has 4 putative miR-375 target sites in its 3'-untranslated region, and this gene was determined to be a target of miR-375. CLDN1 messenger RNA and protein expression were attenuated by overexpression of miR-375 and increased by knockdown of miR-375 in NSCLC cell lines. In a luciferase-reporter assay, miR-375 overexpression resulted in a 3-fold repression of luciferase activity (P<. 0.001). Cell migration was promoted by miR-375 overexpression, suggesting a high potential for invasion and metastasis in NSCLC expressing high levels of miR-375. In clinical NSCLC samples, there was a negative correlation between miR-375 and CLDN1 expression (r = -0.35, P = 0.005). In addition, high miR-375 expression was correlated with a shorter survival time among the clinical samples (P = 0.043). Conclusion: CLDN1 is a novel target of miR-375, and high miR-375 expression shortens survival in NSCLC.

The discovery of somatic mutations in EGFR and development of EGFR tyrosine kinase inhibitors (TKI) have revolutionized treatment for lung cancer. However, resistance to TKIs emerges in almost all patients and currently no effective treatment is available. Here, we show that β-catenin is essential for development of EGFR-mutated lung cancers. β-Catenin was upregulated and activated in EGFR-mutated cells. Mutant EGFR preferentially bound to and tyrosine phosphorylated β-catenin, leading to an increase in β-catenin-mediated transactivation, particularly in cells harboring the gefitinib/erlotinib-resistant gatekeeper EGFR-T790M mutation. Pharmacologic inhibition of β-catenin suppressed EGFR-L858R-T790M mutated lung tumor growth, and genetic deletion of the β-catenin gene dramatically reduced lung tumor formation in EGFR-L858R-T790M transgenic mice. These data suggest that b-catenin plays an essential role in lung tumorigenesis and that targeting the β-catenin pathway may provide novel strategies to prevent lung cancer development or overcome resistance to EGFR TKIs.

Introduction: The multitargeted tyrosine kinase inhibitor (TKI) crizotinib is active against ALK translocated non-small-cell lung cancer (NSCLC); however acquired resistance invariably develops over time. ALK mutations have previously been implicated in only a third of resistant tumors. We sought to evaluate alternative mechanisms of resistance and preclinical strategies to overcome these in a cell line driven by EML4-ALK. Methods: We selected the NSCLC cell line NCI-H3122 (H3122: EML4- ALK E13;A20) and derived resistant variants that were able to grow in the presence of 1. μM crizotinib. These were analyzed for ALK mutations, sensitivity to crizotinib in combination with other TKIs, and for activation of alternative tyrosine kinases. Results: All H3122 crizotinib resistant (CR) clones lacked amplification or mutations in the kinase domain of ALK. To evaluate if possible alternative kinases functioned as "bypass" tracks for downstream signaling activation in these resistance cells, we performed of phosho-receptor tyrosine kinase array that demonstrated that CR clones had higher phospho-EGFR signals than H3122 cells before and after exposure to crizotinib. A functional approach of dual ALK TKI (with crizotinib) with combinatory TKI inhibition was used as a secondary screen for possible targets. Crizotinib. +. erlotinib (reversible EGFR TKI) and crizotinib. +. afatinib (irreversible EGFR/ERBB2 TKI) were able to inhibit the growth of H3122 CR clones, confirming EGFR activation as a mechanism of resistance. The removal of crizotinib from the culture media re-sensitized CR cells to crizotinib. Conclusions: We identified activation of EGFR as a mechanism of resistance to crizotinib in preclinical models of ALK translocated NSCLC. If EGFR activation is confirmed as a predominant mechanism of ALK TKI-induced resistance in patient-derived tumors, the use of ALK plus EGFR TKIs could be explored for this important cohort of NSCLCs. © 2013 Elsevier Ireland Ltd.

Epidermal growth factor receptor (EGFR) gene mutations (G719X, exon 19 deletions/insertions, L858R, and L861Q) predict favorable responses to EGFR tyrosine kinase inhibitors (TKIs) in advanced non-small cell lung cancer (NSCLC). However, EGFR exon 20 insertion mutations (∼10% of all EGFR mutations) are generally associated with insensitivity to available TKIs (gefitinib, erlotinib, and afatinib). The basis of this primary resistance is poorly understood. We studied a broad subset of exon 20 insertion mutations, comparing in vitro TKI sensitivity with responses to gefitinib and erlotinib in NSCLC patients, and found that most are resistant to EGFR TKIs. The crystal structure of a representative TKI-insensitive mutant (D770-N771insNPG) reveals an unaltered adenosine triphosphate-binding pocket, and the inserted residues form a wedge at the end of the C helix that promotes the active kinase conformation. Unlike EGFR-L858R, D770-N771insNPG activates EGFR without increasing its affinity for EGFR TKIs. Unexpectedly, we find that EGFR-A763-Y764insFQEA is highly sensitive to EGFR TKIs in vitro, and patients whose NSCLCs harbor this mutation respond to erlotinib. Analysis of the A763-Y764insFQEA mutant indicates that the inserted residues shift the register of the C helix in the N-terminal direction, altering the structure in the region that is also affected by the TKI-sensitive EGFR-L858R. Our studies reveal intricate differences between EGFR mutations, their biology, and their response to EGFR TKIs.

Patients with non-small cell lung cancer (NSCLC) that harbors epidermal growth factor receptor (EGFR) mutations initially respond to EGFR-tyrosine kinase inhibitors (TKI) but eventually experience relapse. Acquired resistance to EGFR-TKIs is strongly associated with patient mortality. Thus, elucidation of the mechanism of acquired resistance to EGFR-TKIs is of great importance. In this study, gefitinib-resistant cell line models were established by long-term exposure to gefitinib using the gefitinib-sensitive lung cancer cell lines, PC9 and HCC827. Expression analyses indicated that both FGFR1 and FGF2 were increased in PC9 gefitinib-resistant (PC9 GR) cells as compared with PC9 naïve (PC9 na) cells. Importantly, proliferation of gefitinib-resistant cells was dependent on the FGF2-FGFR1 pathway. Mechanistically, inhibition of either FGF2 or FGFR1 by siRNA or FGFR inhibitor (PD173074) restored gefitinib sensitivity in PC9 GR cells. These data suggest that FGF2-FGFR1 activation through an autocrine loop is a novel mechanism of acquired resistance to EGFR-TKIs. © 2013 American Association for Cancer Research.

Purpose: We sought to determine the mechanisms of downregulation of the airway transcription factor Foxa2 in lung cancer and the expression status of Foxa2 in non-small-cell lung cancer (NSCLC). Methods: A series of 25 lung cancer cell lines were evaluated for Foxa2 protein expression, FOXA2 mRNA levels, FOXA2 mutations, FOXA2 copy number changes and for evidence of FOXA2 promoter hypermethylation. In addition, 32 NSCLCs were sequenced for FOXA2 mutations and 173 primary NSCLC tumors evaluated for Foxa2 expression using an immunohistochemical assay. Results: Out of the 25 cell lines, 13 (52%) had undetectable FOXA2 mRNA. The expression of FOXA2 mRNA and Foxa2 protein were congruent in 19/22 cells (p= 0.001). FOXA2 mutations were not identified in primary NSCLCs and were infrequent in cell lines. Focal or broad chromosomal deletions involving FOXA2 were not present. The promoter region of FOXA2 had evidence of hypermethylation, with an inverse correlation between FOXA2 mRNA expression and presence of CpG dinucleotide methylation (p< 0.0001). In primary NSCLC tumor specimens, there was a high frequency of either absence (42/173, 24.2%) or no/low expression (96/173, 55.4%) of Foxa2. In 130 patients with stage I NSCLC there was a trend towards decreased survival in tumors with no/low expression of Foxa2 (HR of 1.6, 95%CI 0.9-3.1; p= 0.122). Conclusions: Loss of expression of Foxa2 is frequent in lung cancer cell lines and NSCLCs. The main mechanism of downregulation of Foxa2 is epigenetic silencing through promoter hypermethylation. Further elucidation of the involvement of Foxa2 and other airway transcription factors in the pathogenesis of lung cancer may identify novel therapeutic targets. © 2012 Elsevier Ireland Ltd.

INTRODUCTION: Most clinically available small-molecule kinase inhibitors are multi-targeted and can inhibit multiple kinases. Our driving hypothesis was that one of these multi-targeted tyrosine kinase inhibitors (TKIs) would have antiproliferative activity against ROS1 translocated non-small-cell lung cancer (NSCLC). METHODS: We selected NSCLC cell lines-A549 (KRAS G12S), NCI-H3255 (EGFR L858R), NCI-H3122 (EML4-ALK E13;A20), and HCC78 (SLC34A2-ROS1)-to evaluate the antiproliferative effects of submicromolar concentrations of the multitargeted TKIs imatinib, sorafenib, erlotinib, and crizotinib. RESULTS: Imatinib and sorafenib were unable to significantly inhibit proliferation of the aforementioned cell lines. Erlotinib only inhibited EGFR mutated NCI-H3255, as expected. Crizotinib displayed dose-dependent inhibition of anaplastic lymphoma kinase translocated NCI-H3122 and also ROS1-translocated HCC78. The SLC34A2-ROS1 translocated HCC78 cell line had phosphorylated levels of ROS1, AKT, and ERK inhibited by submicromolar doses of crizotinib, and subsequently underwent apoptosis. CONCLUSIONS: The ROS1-translocated HCC78 cell line was sensitive to inhibition by the multitargeted ALK/MET/RON/ROS1 inhibitor crizotinib. Preclinical data supports the clinical development of crizotinib for ROS1-translocated NSCLC. Copyright © 2012 by the International Association for the Study of Lung Cancer.

Background: Several sensitive assays, including the PCR-invader method (structure-specific 5 nuclease-based method), have been used to detect EGFR mutations in non-small-cell lung cancer (NSCLC). However, validation has not been reported. We assessed the detection rate of EGFR mutation by the PCR-invader method and direct sequencing using same clinical specimens. Patients and methods: EGFR mutations were analyzed with the PCR-invader method and compared with direct sequencing using paraffin tissues and pleural and pericardial effusions from NSCLC patients. The relationships between the treatment responses and mutations were evaluated retrospectively. Results: Fifty-four samples from 42 NSCLC patients were studied. EGFR mutations were identified in 52% of the patients and 52% of the samples with the PCR-invader method, but only in 43% of the patients and in 35% of the samples by direct sequencing. In the samples obtained from the same patients at different sites and different times, EGFR mutations were coincident in nine out of ten patients by the PCR-invader method but in six out of ten patients by direct sequencing. Seventeen patients with EGFR mutations were treated with gefitinib; the response rate (RR) and disease control rate (DCR) were 41 and 94%, and median treatment duration was more than 6 months. Seven EGFR mutation-negative patients were treated with gefitinib; the RR and DCR were 0 and 14%, and median treatment duration was 1 month. Conclusion: The PCR-invader method was useful for detecting EGFR mutations in clinical lung cancer specimens and is more sensitive than direct sequencing. © 2011 Japan Society of Clinical Oncology.