AI-2-dependent gene regulation in Staphylococcus epidermidis

© 2008 Li et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

A single-arm phase II trial of pazopanib in patients with advanced non-small cell lung cancer with non-squamous histology with disease progression on bevacizumab containing therapy

Platinum-based chemotherapy with bevacizumab is a standard therapy for patients with stage IIIB/IV non-small cell lung cancer (NSCLC) with non-squamous (NS) histology. Mechanisms of resistance to bevacizumab include increased VEGF signaling or activation of VEGF receptors. Pazopanib is a multi-targeted VEGF receptor tyrosine kinase with single agent activity in NSCLC

Phase 2 Study of Dabrafenib Plus Trametinib in Patients With BRAF V600E-Mutant Metastatic NSCLC:Updated 5-Year Survival Rates and Genomic Analysis

Introduction: Dabrafenib plus trametinib was found to have robust antitumor activity in patients with BRAF V600E-mutant metastatic NSCLC (mNSCLC). We report updated survival analysis of a phase 2 study (NCT01336634) with a minimum of 5-year follow-up and updated genomic data. Methods: Pretreated (cohort B) and treatment-naive (cohort C) patients with BRAF V600E-mutant mNSCLC received dabrafenib 150 mg twice daily and trametinib 2 mg once daily. The primary end point was investigator-assessed overall response rate per Response Evaluation Criteria in Solid Tumors version 1.1. Secondary end points were duration of response, progression-free survival, overall survival, and safety. Results: At data cutoff, for cohorts B (57 patients) and C (36 patients), the median follow-up was 16.6 (range: 0.5–78.5) and 16.3 (range: 0.4–80) months, overall response rate (95% confidence interval [CI]) was 68.4% (54.8–80.1) and 63.9% (46.2–79.2), median progression-free survival (95% CI) was 10.2 (6.9–16.7) and 10.8 (7.0–14.5) months, and median overall survival (95% CI) was 18.2 (14.3–28.6) and 17.3 (12.3–40.2) months, respectively. The 4- and 5-year survival rates were 26% and 19% in pretreated patients and 34% and 22% in treatment-naive patients, respectively. A total of 17 patients (18%) were still alive. The most frequent adverse event was pyrexia (56%). Exploratory genomic analysis indicated that the presence of coexisting genomic alterations might influence clinical outcomes in these patients; however, these results require further investigation. Conclusions: Dabrafenib plus trametinib therapy was found to have substantial and durable clinical benefit, with a manageable safety profile, in patients with BRAF V600E-mutant mNSCLC, regardless of previous treatment

First-Line Nivolumab in Stage IV or Recurrent Non-Small-Cell Lung Cancer.

Nivolumab has been associated with longer overall survival than docetaxel among patients with previously treated non-small-cell lung cancer (NSCLC). In an open-label phase 3 trial, we compared first-line nivolumab with chemotherapy in patients with programmed death ligand 1 (PD-L1)-positive NSCLC. We randomly assigned, in a 1:1 ratio, patients with untreated stage IV or recurrent NSCLC and a PD-L1 tumor-expression level of 1% or more to receive nivolumab (administered intravenously at a dose of 3 mg per kilogram of body weight once every 2 weeks) or platinum-based chemotherapy (administered once every 3 weeks for up to six cycles). Patients receiving chemotherapy could cross over to receive nivolumab at the time of disease progression. The primary end point was progression-free survival, as assessed by means of blinded independent central review, among patients with a PD-L1 expression level of 5% or more. Among the 423 patients with a PD-L1 expression level of 5% or more, the median progression-free survival was 4.2 months with nivolumab versus 5.9 months with chemotherapy (hazard ratio for disease progression or death, 1.15; 95% confidence interval [CI], 0.91 to 1.45; P=0.25), and the median overall survival was 14.4 months versus 13.2 months (hazard ratio for death, 1.02; 95% CI, 0.80 to 1.30). A total of 128 of 212 patients (60%) in the chemotherapy group received nivolumab as subsequent therapy. Treatment-related adverse events of any grade occurred in 71% of the patients who received nivolumab and in 92% of those who received chemotherapy. Treatment-related adverse events of grade 3 or 4 occurred in 18% of the patients who received nivolumab and in 51% of those who received chemotherapy. Nivolumab was not associated with significantly longer progression-free survival than chemotherapy among patients with previously untreated stage IV or recurrent NSCLC with a PD-L1 expression level of 5% or more. Overall survival was similar between groups. Nivolumab had a favorable safety profile, as compared with chemotherapy, with no new or unexpected safety signals. (Funded by Bristol-Myers Squibb and others; CheckMate 026 ClinicalTrials.gov number, NCT02041533 .)

Subtype-specific KRAS mutations in advanced lung adenocarcinoma: A retrospective study of patients treated with platinum-based chemotherapy

Background: Platinum-based chemotherapy is the most common treatment in advanced-stage lung adenocarcinoma. Because the clinical significance of KRAS mutational status in this setting has not yet been clearly determined, a mutation subtype-specific analysis was performed in the so far largest cohort of Caucasian patients with KRAS mutant advanced-stage lung adenocarcinoma treated with platinum-based chemotherapy. Methods: 505 Caucasian stage III-IV lung adenocarcinoma patients with known amino acid substitution-specific KRAS mutational status and treated with platinum-based chemotherapy were included. The correlations of subtype-specific KRAS mutations with smoking status, progression-free and overall survival (PFS and OS, respectively) and therapeutic response were analysed. Results: Among 338 KRAS wild-type, 147 codon 12 mutant and 20 codon 13 mutant patients, there were no mutation-related significant differences in PFS or OS (P values were 0.534 and 0.917, respectively). Eastern Cooperative Oncology Group (ECOG) status and clinical stage were significant independent prognostic factors. KRAS mutation showed a significant correlation with smoking status (P = 0.018). Importantly, however, G12V KRAS mutant patients were significantly more frequent among never-smokers than all other codon 12 KRAS mutant (G12x) subtypes (P = 0.016). Furthermore, this subgroup tended to have a higher response rate (66% versus 47%; P = 0.077). A modestly longer median PFS was also found in the G12V mutant cohort (233 days; versus 175 days in the G12x group; P = 0.145). Conclusions: While KRAS mutation status per se is neither prognostic nor predictive in stage III-IV lung adenocarcinoma, subtype-specific analysis may indeed identify clinically relevant subgroups of patients that may ultimately influence treatment decisions. © 2014 The Authors

Aureusimines in Staphylococcus aureus Are Not Involved in Virulence

virulence. Surprisingly, most of the virulence genes affected by aureusimines form part of the regulon of the SaeRS two component system (TCS), raising the possibility that SaeRS might be directly or indirectly involved in the aureusimine-dependent signaling process. mutant was highly enriched in a mixed culture experiment.-mediated virulence factor production or contribute to staphylococcal virulence

Population Structure of Staphylococcus aureus from Remote African Babongo Pygmies

Staphylococcus aureus is a bacterium that colonizes humans worldwide. The anterior nares are its main ecological niche. Carriers of S. aureus are at a higher risk of developing invasive infections. Few reports indicated a different clonal structure and profile of virulence factors in S. aureus isolates from Sub-Saharan Africa. As there are no data about isolates from remote indigenous African populations, we conducted a cross-sectional survey of S. aureus nasal carriage in Gabonese Babongo Pygmies. The isolates were characterized regarding their susceptibility to antibiotic agents, possession of virulence factors and clonal lineage. While similar carriage rates were found in populations of industrialized countries, isolates that encode the genes for the Panton-Valentine leukocidin (PVL) were clearly more prevalent than in European countries. Of interest, many methicillin-susceptible S. aureus isolates from Babongo Pygmies showed the same genetic background as pandemic methicillin-resistant S. aureus (MRSA) clones. We advocate a surveillance of S. aureus in neglected African populations to control the development of resistance to antibiotic drugs with particular respect to MRSA and to assess the impact of the high prevalence of PVL-positive isolates

Genetic Pathway in Acquisition and Loss of Vancomycin Resistance in a Methicillin Resistant Staphylococcus aureus (MRSA) Strain of Clonal Type USA300

An isolate of the methicillin-resistant Staphylococcus aureus (MRSA) clone USA300 with reduced susceptibility to vancomycin (SG-R) (i.e, vancomycin-intermediate S. aureus, VISA) and its susceptible “parental” strain (SG-S) were recovered from a patient at the end and at the beginning of an unsuccessful vancomycin therapy. The VISA phenotype was unstable in vitro generating a susceptible revertant strain (SG-rev). The availability of these 3 isogenic strains allowed us to explore genetic correlates of antibiotic resistance as it emerged in vivo. Compared to the susceptible isolate, both the VISA and revertant strains carried the same point mutations in yycH, vraG, yvqF and lspA genes and a substantial deletion within an intergenic region. The revertant strain carried a single additional frameshift mutation in vraS which is part of two component regulatory system VraSR. VISA isolate SG-R showed complex alterations in phenotype: decreased susceptibility to other antibiotics, slow autolysis, abnormal cell division and increased thickness of cell wall. There was also altered expression of 239 genes including down-regulation of major virulence determinants. All phenotypic properties and gene expression profile returned to parental levels in the revertant strain. Introduction of wild type yvqF on a multicopy plasmid into the VISA strain caused loss of resistance along with loss of all the associated phenotypic changes. Introduction of the wild type vraSR into the revertant strain caused recovery of VISA type resistance. The yvqF/vraSR operon seems to function as an on/off switch: mutation in yvqF in strain SG-R turns on the vraSR system, which leads to increase in vancomycin resistance and down-regulation of virulence determinants. Mutation in vraS in the revertant strain turns off this regulatory system accompanied by loss of resistance and normal expression of virulence genes. Down-regulation of virulence genes may provide VISA strains with a “stealth” strategy to evade detection by the host immune system