Epidermal growth factor receptor mutants from human lung cancers exhibit enhanced catalytic activity and increased sensitivity to gefitinib

Somatic mutations within the epidermal growth factor receptor (EGFR) kinase domain are detected in 10% to 30% of human non-small cell lung cancers and are correlated with striking clinical responses in a subset of patients treated with EGFR kinase inhibitors, such as gefitinib and erlotinib. Cell-based studies suggest that these mutant EGFRs promote increased autophosphorylating activity on a subset of EGFR COOH-terminal tyrosines and the consequent engagement of a subset of downstream effectors. Because EGFR function is regulated at multiple levels in vivo, and it is therefore difficult to assess the direct consequences of these mutations on EGFR enzyme function, we measured EGFR catalytic activity in in vitro kinase assays using purified recombinant proteins corresponding to the cytoplasmic domain of wild-type and two frequently detected EGFR mutants (DelL747-P753insS and L858R). Both mutants exhibit substantially increased autophosphorylating activity relative to wild-type EGFR, and they exhibit distinct reaction kinetics. In addition, the mutant kinases are more sensitive to kinase inhibition by gefitinib, which seems to reflect their increased drug affinity. These findings suggest that the altered signaling properties and drug sensitivity of these EGFR mutants that have been observed in vivo largely result from differences in the catalytic properties of the kinase. In addition, we find that the T790M secondary "drug resistance mutation" of EGFR, which frequently arises in relapsed patients that initially responded to treatment, confers enhanced kinase activity to primary activating EGFR alleles and may, therefore, be oncogenic in some contexts.     

Pyrazolo-pyrimidine-derived c-Src inhibitor reduces angiogenesis and survival of squamous carcinoma cells by suppressing vascular endothelial growth factor production and signaling

Src tyrosine kinase family cooperates with activated growth factor receptors to regulate growth, invasion and metastasis. The authors examined the influence of a novel c-Src inhibitor, 1l, derived from 4-amino-substituted-pyrazolo-pyrimidines, on tumor angiogenesis and on the angiogenic output of squamous carcinoma cells, A431 and SCC-4. The effect of 1l was assessed on growth and microvessel density in A431 tumors and its effect compared with the established c-Src inhibitor PP-1. The effects of c-Src inhibition were investigated on vascular endothelial growth factor (VEGF) expression and activity in tumor cells grown in vivo and in vitro, as well as on VEGF mediated signaling and on endothelial cell functions. Nanomolar concentrations of 1l decreased tumor volume promoted by A431 implanted in nude mice, without affecting in vitro cell tumor survival. This effect was related to 1l inhibition of VEGF production, and secondary to an effect on tumor microvessel density. The rabbit cornea assay confirmed that 1l markedly decreased neovessel growth induced by VEGF. In cultured endothelial cells, 1l inhibited the VEGF-induced phosphorylation on tyr416 of c-Src, resulting in a reduced cell proliferation and invasion. Consistently, 1l dowregulated endothelial nitric oxide synthase, MAPK-extracellular receptor kinase 1-2 (ERK1-2) activity and matrix metalloproteinases (MMP-2/MMP-9), while the tissue inhibitors of metalloproteinases (TIMP2/TIMP-1) were upregulated. These results demonstrate that nM concentrations of c-Src kinase inhibitors (1l and PP-1), by reducing the production of VEGF released by tumor cell and its endothelial cell responses, have a highly selective antiangiogenesis effect, which might be useful in combination therapies.     

Tumor’host interaction in the optimization of paclitaxel-based combination therapies with vascular targeting compounds

Targeting of the tumor stroma, including the tumor vasculature, represents a new frontier in the treatment of malignancy. Preclinical studies and clinical experiences have established that stroma-directed novel agents must be combined with conventional therapies in order to achieve relevant therapeutic efficacy. Here we review our preclinical experience on combinations of paclitaxel with a tyrosine kinase receptor inhibitor of angiogenesis (SU6668) and a vascular disrupting agent (VDA, ZD6126), and discuss the critical factors that determine the outcome of these treatments. We also analyze the relevance of the intrinsic sensitivity of the tumor to the drugs, as well as the possibility that the two combined agents synergistically affect the vasculature or independently target the host and the tumor compartments. Finally, we discuss the need to carefully optimize scheduling and sequencing, through the use of reliable end points, in order to avoid negative pharmacological interactions and to improve the antineoplastic efficacy of paclitaxel-based combination treatments.     

Patterns of care for brachytherapy in Europe, in Spain and Italy: comparative results

AIMS AND BACKGROUND: The aim of the study was to compare the facilities for brachytherapy in two similar countries, as are Italy and Spain. This survey reports the differences in the use of brachytherapy in these countries. METHODS: The data regarding brachytherapy was obtained in 2002 by means of a specially designed web site, because Internet allowed the access to the questionnaire in an easy and safe way. In the first edition of the survey, only the countries in which more than 50% of its centers had completed the questionnaire were included. Among these countries there were Italy and Spain. RESULTS: Data was available in 127 centers in Italy and 72 centers in Spain, where 35 and 39, respectively, provided brachytherapy. Although both countries had a similar number of radiotherapy patients and the average number of radiotherapy patients per center was similar in both countries (P = 0.29), there were several differences related to brachytherapy. For instance, the mean number of radiation oncologists regularly performing brachytherapy per center was higher in Spain (P = 0.001). There were also differences in the average number of patients per center in the following tumor sites: breast (P < 0.001) and gynaecological (P < 0.001). In fact, the average number of patients per center who were treated with brachytherapy in these tumor sites was higher in Spain than Italy. CONCLUSIONS: Although the estimated workload of the radiation oncologists, physicists and radiation technologists was higher in Spain, no statistically significant differences were found in the average number of patients per center for the following tumor sites: bronchus, head and neck, intracoronary, esophagus, prostate, rectum and skin. Several differences in the use of the brachytherapy procedures applied were also found.     

Impact of Global Economic Disparities on Practices and Outcomes of Chronic Peritoneal Dialysis in Children: Insights from the International Pediatric Peritoneal Dialysis Network Registry

Background, Objectives, and METHODS: The number of patients on chronic peritoneal dialysis (CPD) is increasing rapidly on a global scale. We analyzed the International Pediatric Peritoneal Dialysis Network (IPPN) registry, a global database active in 33 countries spanning a wide range in gross national income (GNI), to identify the impact of economic conditions on CPD practices and outcomes in children and adolescents. ? RESULTS: We observed close associations of GNI with the fraction of very young patients on dialysis, the presence and number of comorbidities, the prevalence of patients with unexplained causes of end-stage kidney disease, and the rate of culture-negative peritonitis. The prevalence of automated PD increased with GNI, but was 46% even in the lowest GNI stratum. The GNI stratum also affected the use of biocompatible peritoneal dialysis fluids, enteral tube feeding, calcium-free phosphate binders, active vitamin D analogs, and erythropoiesis-stimulating agents (ESAs). Patient mortality was strongly affected by GNI (hazard ratio per $10 000: 3.3; 95% confidence interval: 2.0 to 5.5) independently of young patient age and the number of comorbidities present. Patients from low-income countries tended to die more often from infections unrelated to CPD (5 of 9 vs 15 of 61, p = 0.1). The GNI was also a strong independent predictor of standardized height (p < 0.0001), adding to the impact of congenital renal disease, anuria, age at PD start, and dialysis vintage. Patients from the lower economic strata (GNI < $18 000) had higher serum parathyroid hormone (PTH) and lower serum calcium, and achieved lower hemoglobin concentrations. No impact of GNI was observed with regard to CPD technique survival or peritonitis incidence. ? CONCLUSIONS: We conclude that CPD is practiced successfully, albeit with major regional variation related to economic differences, in children around the globe. The variations encompass the acceptance of very young patients and those with associated comorbidities to chronic dialysis programs, the use of automated PD and expensive drugs, and the diagnostic management of peritonitis. These variations in practice related to economic difference do not appear to affect PD technique survival; however, economic conditions seem to affect mortality on dialysis and standardized height, a marker of global child morbidity.     

Síndrome de burnout y riesgo suicida en enfermeras de atención primaria

ObjectiveTo observe the prevalence of the burnout syndrome and the relationship with suicide risk, self-esteem, anxiety and depression, in a sample of primary care nurses.MethodObservational, cross-sectional and correlational study. The sample consisted of 146 nursing professionals, 131 women and 15 men, with an average age of 44.02 years (SD=10.89). Participants responded to a questionnaire which included the Spanish forms of the Maslach burnout inventory (MBI), the Plutchik Suicide Risk Scale (SR), the Kuwait University Anxiety Scale (KUAS), the Self-Rating Depression Scale (SDS) and the Rosenberg Self-esteem Scale (RSES). In the inferential statistical analysis, Pearson's r coefficients and multiple linear regression were calculated.ResultsSignificant correlations between suicidal risk and anxiety, depression, self-esteem, emotional exhaustion and personal performance, were obtained. In the multiple regression analysis, depression was the main predictor of suicidal risk, followed by anxiety and emotional exhaustion.ConclusionsThe scores obtained in burnout and suicidal risk were, in general, lower than those observed in other studies, emphasising the high level observed in personal performance, which reflects reasonable professional satisfaction. The results show the important role of working atmosphere and early recognition of mental disorders in burnout and suicidal risk prevention.     

Clinical Outcome in Patients with Intermediate Stenosis of Left Anterior Descending Coronary Artery after Deferral of Revascularization on the Basis of Noninvasive Coronary Flow Reserve Measurement

Background: Several reports suggest that noninvasive measurements of coronary flow reserve (CFR) by use of echocardiography may support decision making in intermediate stenosis of the left anterior descending coronary artery (LAD). The aim of the present study was therefore to analyze the clinical outcome in patients with intermediate stenosis of LAD after deferral of coronary revascularization on the basis of noninvasive CFR measurement. Methods: the study population included 280 patients with intermediate LAD stenosis (50–70% by angiography) (62.2 ± 9.6 years). All the patients underwent transthoracic CFR assessment of LAD (after dipyridamole infusion) within 2 weeks from coronary angiography. If CFR of LAD was ≤ 2, PTCA was recommended; if CFR was > 2, medical treatment was chosen. Primary end points were cardiac death, myocardial infarction, coronary revascularization procedure, and unstable angina. Results: mean follow-up was 43 ± 11 months (range 12–52 months). In 150 patients (53.6%) (CFR ≤ 2), coronary artery revascularization was performed (PTCA group); the remaining 130 patients (46.4%) (CFR > 2) were medically treated (medical group). Survival from cardiac death was 94% in the PTCA group and 92.4% in the medical group (P = 0.56). As for all cardiac events, the Kaplan–Meier percentage survival from cardiac events was 88.3% in the PTCA group and 86.4% in the medical group (P = 0.36). Conclusions: even if CFR as a "stand-alone" diagnostic criterion suffers from several structural limitations, a combined strategy including also other clinical and instrumental measurements before undergoing interventional procedures could improve the cost–benefit practice, in particular, for the management of patients with intermediate LAD stenosis.