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Jeeyeon Kim, Miesha Farahmand, Colleen Dunn, Zoe Davies, Eric Frisbee, Carlos Milla, Jeffrey J Wine
Beta-adrenergically-stimulated sweat rates determined by evaporimetry or by sweat bubble imaging are useful for measuring CFTR function because they provide a near-linear readout across almost the full range of CFTR function. They differentiate cystic fibrosis (CF) subjects from CF carriers and carriers from controls. However, evaporimetry, unlike bubble imaging, appears to be unable to detect improved levels of CFTR function in G551D subjects taking the CFTR modulator ivacaftor. Here, we quantify the sensitivity of evaporimetry and bubble imaging methods for assessing low levels of CFTR-dependent sweat rates...
2016: PloS One
Isabelle Sermet-Gaudelus, Martial Delion, Isabelle Durieu, Jacky Jacquot, Dominique Hubert
Low bone mineral density (BMD) is a common problem in adults with cystic fibrosis (CF), the etiology of which is multifactorial. In this study, we provide the first evidence that ivacaftor improves BMD in CF patients carrying the p.Gly551Asp mutation. Consistently, in vitro experiments with TNF-α-stimulated primary F508del-CFTR osteoblasts demonstrated that correction of p.Phe508del-CFTR markedly decreased RANKL protein production, a major factor of bone resorption. These clinical and fundamental observations suggest that rescue of mutated CFTR protein improves bone remodeling and support the link between CFTR and bone cell physiology...
October 10, 2016: Journal of Cystic Fibrosis: Official Journal of the European Cystic Fibrosis Society
Venkateshwar Mutyam, Emily Falk Libby, Ning Peng, Denis Hadjiliadis, Michael Bonk, George M Solomon, Steven M Rowe
Premature termination codons (PTCs) in cystic fibrosis transmembrane conductance regulator (CFTR) gene result in nonfunctional CFTR protein and are the proximate cause of ~11% of CF causing alleles. Aminoglycosides and other novel agents are known to induce translational readthrough of PTCs, a potential therapeutic approach. Among PTCs, W1282X CFTR is unique, as it is a C-terminal CFTR mutation that can exhibit partial activity, even in the truncated state. The potentiator ivacaftor (VX-770) is approved for treating CF patients with G551D and other gating mutations...
October 1, 2016: Journal of Cystic Fibrosis: Official Journal of the European Cystic Fibrosis Society
Cameron L Jordan, Terry L Noah, Marianna M Henry
This review seeks to re-introduce cystic fibrosis (CF) clinicians to the pharmacology of drug-drug interactions among medications commonly used in CF and provide a framework for understanding these interactions among medications outside the scope of this discussion. We here focus on drugs impacted by the cytochrome P-450 (CYP450) enzyme system and on interactions involving antimicrobials, psychotropic medications, and cystic fibrosis transmembrane conductance regulator (CFTR) modulators. Particular attention is needed when prescribing rifampin, azole antifungals and the CFTR modulators, ivacaftor, and lumacaftor/ivacaftor, in combination with other medications...
October 2016: Pediatric Pulmonology
Carleen M Sabusap, Wei Wang, Carmel M McNicholas, W Joon Chung, Lianwu Fu, Hui Wen, Marina Mazur, Kevin L Kirk, James F Collawn, Jeong S Hong, Eric J Sorscher
Emerging knowledge indicates the difficulty in categorizing unusual cystic fibrosis (CF) mutations, with regard to both pathogenic mechanism and theratype. As case in point, we present data concerning P67L mutation of the cystic fibrosis transmembrane conductance regulator (CFTR), a defect carried by a small number of individuals with CF and sometimes attributed to a channel conductance abnormality. Findings from our laboratory and others establish that P67L causes protein misfolding, disrupts maturation, confers gating defects, is thermally stable, and exhibits near normal conductance...
September 8, 2016: JCI Insight
Myriam Mesbahi, Michal Shteinberg, Michael Wilschanski, Aurelie Hatton, Thao Nguyen-Khoa, Hannah Friedman, Michael Cohen, Virginie Escabasse, Muriel Le Bourgeois, Vicenzina Lucidi, Isabelle Sermet-Gaudelus, Laurence Bassinet, Galit Livnat
Ivacaftor, a CFTR potentiator, has been found to improve CFTR function and clinical outcomes in patients with cystic fibrosis (CF) gating mutations. We investigated the effects of ivacaftor on CFTR functional measurement in CF patients carrying gating mutations other than p.Gly551Asp. Two siblings aged 13 and 12 carrying the p.Ser549Asn mutation, two sisters (45 and 43years old) compound heterozygotes for p.Asp1152His and p.Gly1244Glu, a 37year old man homozygous for the p.Gly1244Glu mutation, and a 7year old girl with p...
September 19, 2016: Journal of Cystic Fibrosis: Official Journal of the European Cystic Fibrosis Society
Alison E Fohner, Ellen M McDonagh, John P Clancy, Michelle Whirl Carrillo, Russ B Altman, Teri E Klein
No abstract text is available yet for this article.
September 15, 2016: Pharmacogenetics and Genomics
Elena K Schneider, Mohammad A K Azad, Mei-Ling Han, Qi Tony Zhou, Jiping Wang, Johnny X Huang, Matthew A Cooper, Yohei Doi, Mark A Baker, Phillip J Bergen, Mark T Muller, Jian Li, Tony Velkov
Novel combination therapies are desperately needed for combating lung infections caused by bacterial "superbugs". This study aimed to investigate the synergistic antibacterial activity of polymyxin B in combination with the cystic fibrosis (CF) drugs KALYDECO (ivacaftor) and ORKAMBI (ivacaftor + lumacaftor) against Gram-negative pathogens that commonly colonize the CF lung, in particular, the problematic Pseudomonas aeruginosa. The in vitro synergistic activity of polymyxin B combined with ivacaftor or lumacaftor was assessed using checkerboard and static time-kill assays against a panel of polymyxin-susceptible and polymyxin-resistant P...
July 8, 2016: ACS Infectious Diseases
Onofrio Laselva, Steven Molinski, Valeria Casavola, Christine E Bear
Cystic Fibrosis (CF) is caused by mutations in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene. The most common mutation, deletion of phenylalanine 508 (F508del), disrupts tertiary assembly, causing protein misprocessing and loss of CFTR function in epithelial tissues. Lumacaftor (VX-809) is a Class 1 corrector molecule shown to partially rescue misprocessing of F508del and together with the potentiator of channel activity: ivacaftor (VX-770) has been approved for treatment of CF patients homozygous for the F508del mutation...
November 1, 2016: Biochemical Pharmacology
S Vamsee Raju, Vivian Y Lin, Limbo Liu, Carmel M McNicholas, Suman Karki, Peter A Sloane, Liping Tang, Patricia L Jackson, Wei Wang, Landon Wilson, Kevin J Macon, Marina Mazur, John Kappes, Lawrence J DeLucas, Stephen Barnes, Kevin Kirk, Guillermo T Tearney, Steven M Rowe
RATIONALE: Acquired CFTR dysfunction may contribute to COPD pathogenesis and is a potential therapeutic target. OBJECTIVES: To determine the acute effects of cigarette smoke on ion transport and the mucociliary transport apparatus, their mechanistic basis; and whether deleterious effects could be reversed with the CFTR potentiator ivacaftor (VX-770). METHODS: Primary human bronchial epithelial cells (HBE) and human bronchi were exposed to cigarette smoke extract (CSE) and/or ivacaftor...
September 1, 2016: American Journal of Respiratory Cell and Molecular Biology
Lisa J Strug, Tanja Gonska, Gengming He, Katherine Keenan, Wan Ip, Pierre-Yves Boëlle, Fan Lin, Naim Panjwani, Jiafen Gong, Weili Li, David Soave, Bowei Xiao, Elizabeth Tullis, Harvey Rabin, Michael D Parkins, April Price, Peter C Zuberbuhler, Harriet Corvol, Felix Ratjen, Lei Sun, Christine E Bear, Johanna M Rommens
Cystic fibrosis is realizing the promise of personalized medicine. Recent advances in drug development that target the causal CFTR directly result in lung function improvement, but variability in response is demanding better prediction of outcomes to improve management decisions. The genetic modifier SLC26A9 contributes to disease severity in the CF pancreas and intestine at birth and here we assess its relationship with disease severity and therapeutic response in the airways. SLC26A9 association with lung disease was assessed in individuals from the Canadian and French CF Gene Modifier consortia with CFTR-gating mutations and in those homozygous for the common Phe508del mutation...
August 29, 2016: Human Molecular Genetics
Gemma L Zeybel, Jeffrey P Pearson, Amaran Krishnan, Stephen J Bourke, Simon Doe, Alan Anderson, Shoaib Faruqi, Alyn H Morice, Rhys Jones, Melissa McDonnell, Mujdat Zeybel, Peter W Dettmar, Malcolm Brodlie, Chris Ward
BACKGROUND: Extra-oesophageal reflux (EOR) may lead to microaspiration in patients with cystic fibrosis (CF), a probable cause of deteriorating lung function. Successful clinical trials of ivacaftor highlight opportunities to understand EOR in a real world study. METHODS: Data from 12 patients with CF and the G551D mutation prescribed ivacaftor (150mg bd) was collected at baseline, 6, 26 and 52weeks. The changes in symptoms of EOR were assessed by questionnaire (reflux symptom index (RSI) and Hull airway reflux questionnaire (HARQ))...
July 27, 2016: Journal of Cystic Fibrosis: Official Journal of the European Cystic Fibrosis Society
Michael Glenn O'Connor, Adam Seegmiller
BACKGROUND: Ivacaftor has produced significant improvement in certain individuals with cystic fibrosis (CF), though the full metabolic effects of treatment remain unknown. Abnormalities in fatty acid metabolism have previously been shown to be a characteristic of CFTR dysfunction. We hypothesized that as a reflection of this clinical improvement, ivacaftor would improve plasma fatty acid levels and decrease urine prostaglandin E metabolite levels. METHODS: This study analyzed plasma fatty acid levels and urine prostaglandin E metabolites (PGE-M) in 40 subjects with CF participating in the G551D observational (GOAL) study who demonstrated response to the medication by a significant decrease in sweat Cl levels...
July 26, 2016: Journal of Cystic Fibrosis: Official Journal of the European Cystic Fibrosis Society
Thida Ong, Bonnie W Ramsey
Cystic fibrosis transmembrane conductance regulator (CFTR) modulators are clinically available personalized medicines approved for some individuals with cystic fibrosis (CF) to target the underlying defect of disease. This review summarizes strategies used to develop CFTR modulators as therapies that improve function and availability of CFTR protein. Lessons learned from dissemination of ivacaftor across the CF population responsive to this therapy and future approaches to predict and monitor treatment response of CFTR modulators are discussed...
August 2016: Pediatric Clinics of North America
Daniel A Hussar, Jerry Rachel George
No abstract text is available yet for this article.
July 2016: Journal of the American Pharmacists Association: JAPhA
Wen-Ying Lin, Yoshiro Sohma, Tzyh-Chang Hwang
Cystic fibrosis (CF) is caused by loss-of-function mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene encoding a phosphorylation-activated but ATP-gated chloride channel. Previous studies suggested that VX-770 [ivacaftor, N-(2,4-di-tert-butyl-5-hydroxyphenyl)-4-oxo-1,4-dihydroquinoline-3-carboxamide], a CFTR potentiator now used in clinics, increases the open probability of CFTR by shifting the gating conformational changes to favor the open channel configuration. Recently the chloride channel blocker and CFTR potentiator 5-nitro-2-(3-phenylpropylamino) benzoate (NPPB) has been reported to enhance CFTR activity by a mechanism that exploits the ATP hydrolysis-driven, nonequilibrium gating mechanism unique to CFTR...
September 2016: Molecular Pharmacology
Emma D Deeks
Lumacaftor/ivacaftor (Orkambi™) is a fixed-dose tablet containing a corrector (lumacaftor) and potentiator (ivacaftor) of the cystic fibrosis transmembrane conductance regulator (CFTR) and is the first therapy approved to treat the underlying cause of cystic fibrosis in patients (aged ≥12 years) homozygous for the most common CFTR mutation, F508del. Lumacaftor improves the processing of F508del CFTR and its transport to the cell surface, while ivacaftor increases the channel's open probability and transport of chloride...
August 2016: Drugs
Daniel L Hamilos
Chronic rhinosinusitis (CRS) is highly prevalent in patients with cystic fibrosis (CF) and accounts for significant morbidity and contribution to CF lung disease. Mutations of the cystic fibrosis transmembrane regulator gene occur with increased prevalence in patients with CRS without CF, suggesting some contribution to CRS pathophysiology. Nasal polyps (NPs) occur with increased prevalence in patients with CF of all ages and have a more neutrophilic appearance with fewer eosinophils and increased submucosal glandular elements in comparison to NPs from patients without CF...
July 2016: Journal of Allergy and Clinical Immunology in Practice
Johanna F Dekkers, Gitte Berkers, Evelien Kruisselbrink, Annelotte Vonk, Hugo R de Jonge, Hettie M Janssens, Inez Bronsveld, Eduard A van de Graaf, Edward E S Nieuwenhuis, Roderick H J Houwen, Frank P Vleggaar, Johanna C Escher, Yolanda B de Rijke, Christof J Majoor, Harry G M Heijerman, Karin M de Winter-de Groot, Hans Clevers, Cornelis K van der Ent, Jeffrey M Beekman
Identifying subjects with cystic fibrosis (CF) who may benefit from cystic fibrosis transmembrane conductance regulator (CFTR)-modulating drugs is time-consuming, costly, and especially challenging for individuals with rare uncharacterized CFTR mutations. We studied CFTR function and responses to two drugs-the prototypical CFTR potentiator VX-770 (ivacaftor/KALYDECO) and the CFTR corrector VX-809 (lumacaftor)-in organoid cultures derived from the rectal epithelia of subjects with CF, who expressed a broad range of CFTR mutations...
June 22, 2016: Science Translational Medicine
Csaba Mihályi, Beáta Töröcsik, László Csanády
In CFTR, the chloride channel mutated in cystic fibrosis (CF) patients, ATP-binding-induced dimerization of two cytosolic nucleotide binding domains (NBDs) opens the pore, and dimer disruption following ATP hydrolysis closes it. Spontaneous openings without ATP are rare in wild-type CFTR, but in certain CF mutants constitute the only gating mechanism, stimulated by ivacaftor, a clinically approved CFTR potentiator. The molecular motions underlying spontaneous gating are unclear. Here we correlate energetic coupling between residues across the dimer interface with spontaneous pore opening/closure in single CFTR channels...
2016: ELife
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