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Background: In two pivotal phase 3 trials, up to 24 weeks of treatment with elexacaftor/tezacaftor/ivacaftor (ELX/TEZ/IVA) was efficacious and safe in patients with cystic fibrosis (CF) ≥12 years of age who have at least one F508del allele. The aim of this study is to assess long-term safety and efficacy of ELX/TEZ/IVA in these patients., Methods: In this phase 3, open-label, single-arm extension study, participants with F508del -minimal function (from a 24-week parent study; n=399) or F508del - F508del (from a 4-week parent study; n=107) genotypes receive ELX/TEZ/IVA at the same dose (ELX 200 mg once daily, TEZ 100 mg once daily and IVA 150 mg every 12 h). The primary end-point is safety and tolerability. A prespecified interim analysis was conducted when the last participant reached the Week 144 visit., Results: At the Week 144 interim analysis, mean duration of exposure to ELX/TEZ/IVA in the extension study was 151.1 weeks. Exposure-adjusted rates of adverse events (AEs) (586.6 events per 100 participant-years) and serious AEs (22.4 events per 100 participant-years) were lower than in the ELX/TEZ/IVA treatment group in the 24-week parent study (1096.0 and 36.9 events per 100 participant-years, respectively); most participants had AEs classified as mild (16.4% of participants) or moderate (60.3% of participants) in severity. 14 participants (2.8%) had AEs that led to treatment discontinuation. Following initiation of ELX/TEZ/IVA, participants had increases in forced expiratory volume in 1 s (FEV 1 ) percentage predicted, Cystic Fibrosis Questionnaire-Revised respiratory domain score and body mass index, and had decreases in sweat chloride concentration and pulmonary exacerbation rates that were maintained over the interim analysis period. The mean annualised rate of change in FEV 1 % pred was +0.07 (95% CI -0.12-0.26) percentage points among the participants., Conclusions: ELX/TEZ/IVA was generally safe and well tolerated, with a safety profile consistent with the 24-week parent study. Participants had sustained improvements in lung function, respiratory symptoms, CF transmembrane conductance regulator function, pulmonary exacerbation rates and nutritional status. These results support the favourable safety profile and durable, disease-modifying clinical benefits of ELX/TEZ/IVA., Competing Interests: Conflicts of interest: All authors received nonfinancial support (assistance with manuscript preparation) from Nucleus Global, which received funding from Vertex Pharmaceuticals Incorporated. C.L. Daines has nothing further to disclose. E. Tullis has received consulting, speaker and travel fees from Vertex Pharmaceuticals. S. Costa serves on an advisory board for Vertex Pharmaceuticals. R.W. Linnemann serves on an advisory board and reports grants paid to her institution and consulting fees from Vertex Pharmaceuticals. M.A. Mall reports patient recruitment fees paid to his institution and advisory fees from Vertex Pharmaceuticals, consulting fees from Antabio, Arrowhead Pharmaceuticals, Boehringer Ingelheim, Enterprise Therapeutics, Santhera, Sterna Biologicals and Vertex Pharmaceuticals, speaker fees from Arrowhead Pharmaceuticals, Boehringer Ingelheim and Vertex Pharmaceuticals, travel fees from Boehringer Ingelheim and Vertex Pharmaceuticals, advisory fees from Antabio, Arrowhead Pharmaceuticals, Boehringer Ingelheim, Enterprise Therapeutics, Kither Biotech, Santhera and Vertex Pharmaceuticals, and serves on the European Cystic Fibrosis Society (ECFS) board. E.F. McKone reports grants, lecture fees and serving on an advisory board for Vertex Pharmaceuticals, lecture fees from Roche, travel fees from A. Menarini, and serving on advisory boards for Janssen, Insmed and CF Storm. D. Polineni reports grants from Laurent Pharmaceuticals, Parion Sciences, Proteostasis Therapeutics and Vertex Pharmaceuticals, consulting fees from Vertex Pharmaceuticals, nonfinancial support for travel to investigator meeting from Vertex Pharmaceuticals, and serves on an advisory board for Sanofi. B.S. Quon reports payments paid to his institution and speaker fees from Vertex Pharmaceuticals. F.C. Ringshausen reports grants paid to his institution from Basilea Pharmaceutica, German Center for Lung Research (DZL), German Center for Infection Research (DZIF), Inhaled Antibiotics in Bronchiectasis and Cystic Fibrosis (iABC)/Innovative Medicines Initiative (IMI), European Federation of Pharmaceutical Industries and Associations (EFPIA), Insmed, Novartis and Polyphor, consulting fees from Grifols, Insmed, Parion, Shionogi and Zambon, speaker fees from AstraZeneca, Boehringer Ingelheim, Chiesi, Grifols, Insmed and Novartis, participation on advisory boards for Grifols, Insmed, Parion, Shionogi and Zambon, unpaid honoraria as co-chair of the German Bronchiectasis Registry (PROGNOSIS), and payments to his institution from AbbVie, AstraZeneca, Boehringer Ingelheim, Corbus, Celtaxsys, Insmed, Novartis, Parion, Polyphor, Vertex and Zambon; and is a steering committee member of the European Bronchiectasis Registry (EMBARC), a steering committee member of the European NTM registry (EMBARC-NTM), a core network lead in ERN-LUNG, a principal investigator for DZL, a chair of the cystic fibrosis working group of the German Respiratory Society (DGP), a steering committee member of the Group of German CF Physicians (AGAM), and co-chair of medical consultants of PCD Patient Advocacy Group (Kartagener Syndrom und Primäre Ciliäre Dyskinesie eV). S.M. Rowe reports grants paid to his institution from AbbVie, Arrowhead Pharmaceuticals, AstraZeneca, Bayer, Celtaxsys, Eloxx, Ionis Pharmaceuticals, Novartis, Proteostasis Therapeutics, Synedgen, Synspira Therapeutics, Translate Bio and Vertex Pharmaceuticals, nonfinancial support from AbbVie, Ionis Pharmaceuticals, Proteostasis Therapeutics, Renovion, Synedgen and Synspira Therapeutics, consulting fees from AbbVie, Arrowhead Pharmaceuticals, Bayer, Cystetic Medicines, Ionis Pharmaceuticals, Novartis, Renovion, Synedgen, Synspira Therapeutics and Vertex Pharmaceuticals, and serves as co-chair for the Next Generation Steering Committee on Vertex Pharmaceuticals. H. Selvadurai has nothing further to disclose. J.L. Taylor-Cousar serves on the board of trustees, clinical research executive committee, clinical research advisory board and Women's Health Research-Working Group for the US Cystic Fibrosis Foundation, serves on the scientific advisory board for Emily's Entourage, serves on the respiratory health awards working group, scientific grants review committee and clinical problems assembly programming committee for the American Thoracic Society; reports consulting fees from 4D Molecular Therapeutics, Celtaxsys, Prolarean Imaging, Protalix Biotherapeutics, Proteostasis Therapeutics and Santhera Pharmaceuticals, grants to her institution from Bayer, Celtaxsys, Eloxx Pharmaceuticals, Gilead, N30 and Proteostasis Therapeutics, speaking fees from Celtaxsys and Gilead, serves on advisory board for AbbVie, Genentech, Insmed and Novartis, and is an associate editor for the Journal of Cystic Fibrosis. N.J. Withers reports lecture fees from Vertex Pharmaceuticals and serves on an advisory board for Vertex Pharmaceuticals and Proteostasis Therapeutics. B. Ramsey reports travel fees and grants from, and serves on advisory board for Vertex Pharmaceuticals, and personal fees from Cystetic Medicines. M. Griese reports grants to his institution from Vertex Pharmaceuticals. N. Ahluwalia, S.M. Moskowitz, V. Prieto-Centurion, Y.V. Tan, S. Tian, T. Weinstock, F. Xuan and Y. Zhang are employees of Vertex and may own stock or stock options in Vertex., (Copyright ©The authors 2023.)

Rationale: The triple-combination regimen elexacaftor/tezacaftor/ivacaftor (ELX/TEZ/IVA) was shown to be safe and efficacious in children aged 6 through 11 years with cystic fibrosis and at least one F508del-CFTR allele in a phase 3, open-label, single-arm study. Objectives: To further evaluate the efficacy and safety of ELX/TEZ/IVA in children 6 through 11 years of age with cystic fibrosis heterozygous for F508del and a minimal function CFTR mutation ( F /MF genotypes) in a randomized, double-blind, placebo-controlled phase 3b trial. Methods: Children were randomized to receive either ELX/TEZ/IVA ( n  = 60) or placebo ( n  = 61) during a 24-week treatment period. The dose of ELX/TEZ/IVA administered was based on weight at screening, with children <30 kg receiving ELX 100 mg once daily, TEZ 50 mg once daily, and IVA 75 mg every 12 hours, and children ⩾30 kg receiving ELX 200 mg once daily, TEZ 100 mg once daily, and IVA 150 mg every 12 hours (adult dose). Measurements and Main Results: The primary endpoint was absolute change in lung clearance index 2.5 from baseline through Week 24. Children given ELX/TEZ/IVA had a mean decrease in lung clearance index 2.5 of 2.29 units (95% confidence interval [CI], 1.97-2.60) compared with 0.02 units (95% CI, -0.29 to 0.34) in children given placebo (between-group treatment difference, -2.26 units; 95% CI, -2.71 to -1.81; P  < 0.0001). ELX/TEZ/IVA treatment also led to improvements in the secondary endpoint of sweat chloride concentration (between-group treatment difference, -51.2 mmol/L; 95% CI, -55.3 to -47.1) and in the other endpoints of percent predicted FEV 1 (between-group treatment difference, 11.0 percentage points; 95% CI, 6.9-15.1) and Cystic Fibrosis Questionnaire-Revised Respiratory domain score (between-group treatment difference, 5.5 points; 95% CI, 1.0-10.0) compared with placebo from baseline through Week 24. The most common adverse events in children receiving ELX/TEZ/IVA were headache and cough (30.0% and 23.3%, respectively); most adverse events were mild or moderate in severity. Conclusions: In this first randomized, controlled study of a cystic fibrosis transmembrane conductance regulator modulator conducted in children 6 through 11 years of age with F /MF genotypes, ELX/TEZ/IVA treatment led to significant improvements in lung function, as well as robust improvements in respiratory symptoms and cystic fibrosis transmembrane conductance regulator function. ELX/TEZ/IVA was generally safe and well tolerated in this pediatric population with no new safety findings.

Background: Elexacaftor plus tezacaftor plus ivacaftor is a triple-combination cystic fibrosis transmembrane conductance regulator (CFTR) modulator regimen shown to be generally safe and efficacious in people with cystic fibrosis aged 12 years or older with at least one F508del-CFTR allele. We aimed to assess the magnitude and durability of the clinical effects of this triple combination regimen in people with cystic fibrosis homozygous for the F508del-CFTR mutation., Methods: We conducted a multicentre, randomised, double-blind, active-controlled, phase 3b trial of elexacaftor plus tezacaftor plus ivacaftor at 35 medical centres in Australia, Belgium, Germany, and the UK. Eligible participants were those with cystic fibrosis homozygous for the F508del-CFTR mutation, aged 12 years or older with stable disease, and with a percent predicted FEV 1 of 40-90% inclusive. After a 4-week run-in period, in which participants received tezacaftor 100 mg orally once daily and ivacaftor 150 mg orally every 12 h, participants were randomly assigned (1:1) to receive 24 weeks of either elexacaftor 200 mg orally once daily plus tezacaftor 100 mg orally once daily plus ivacaftor 150 mg orally every 12 h (elexacaftor plus tezacaftor plus ivacaftor group) or tezacaftor 100 mg orally once daily plus ivacaftor 150 mg orally every 12 h (tezacaftor plus ivacaftor group). Randomisation was stratified by percent predicted FEV 1 , age at screening visit, and whether the participant was receiving CFTR modulators at the time of the screening visit. Patients, investigators, and sponsor's study execution team were masked to treatment assignment. The primary endpoint was the absolute change in Cystic Fibrosis Questionnaire-Revised (CFQ-R) respiratory domain score from baseline (ie, at the end of the tezacaftor plus ivacaftor run-in period) up to and including week 24. The key secondary endpoint was the absolute change from baseline in percent predicted FEV 1 up to and including week 24; other secondary endpoints were the absolute change from baseline in sweat chloride concentrations up to and including week 24, and safety and tolerability. All endpoints were assessed in all randomised patients who had received at least one dose of their assigned regimen. This study is registered with ClinicalTrials.gov, NCT04105972., Findings: Between Oct 3, 2019, and July 24, 2020, 176 participants were enrolled. Following the 4-week tezacaftor plus ivacaftor run-in period, 175 participants were randomly assigned (87 to the elexacaftor plus tezacaftor plus ivacaftor group and 88 to the tezacaftor plus ivacaftor group) and dosed in the treatment period. From baseline up to and including week 24, the mean CFQ-R respiratory domain score increased by 17·1 points (95% CI 14·1 to 20·1) in the elexacaftor plus tezacaftor plus ivacaftor group and by 1·2 points (-1·7 to 4·2) in the tezacaftor plus ivacaftor group (least squares mean treatment difference 15·9 points [95% CI 11·7 to 20·1], p<0·0001), the mean percent predicted FEV 1 increased by 11·2 percentage points (95% CI 9·8 to 12·6) in the elexacaftor plus tezacaftor plus ivacaftor group and by 1·0 percentage points (-0·4 to 2·4) in the tezacaftor plus ivacaftor group (least squares mean treatment difference 10·2 percentage points [8·2 to 12·1], p<0·0001), and the mean sweat chloride concentration decreased by 46·2 mmol/L (95% CI 43·7 to 48·7) in the elexacaftor plus tezacaftor plus ivacaftor group and by 3·4 mmol/L (1·0 to 5·8) in the tezacaftor plus ivacaftor group (least squares mean treatment difference -42·8 mmol/L [-46·2 to -39·3], nominal p<0·0001). Most participants (70 [80%] in the elexacaftor plus tezacaftor plus ivacaftor group and 74 [84%] in the tezacaftor plus ivacaftor group) had adverse events that were mild or moderate in severity; serious adverse events occurred in five (6%) of 87 participants in the elexacaftor plus tezacaftor plus ivacaftor group and 14 (16%) of 88 participants in the tezacaftor plus ivacaftor group. One (1%) participant in the elexacaftor plus tezacaftor plus ivacaftor group discontinued treatment due to an adverse event of anxiety and depression. Two (2%) participants in the tezacaftor plus ivacaftor group discontinued treatment due to adverse events of psychotic disorder (n=1) and obsessive-compulsive disorder (n=1)., Interpretation: The elexacaftor plus tezacaftor plus ivacaftor regimen was safe and well tolerated, and led to significant and clinically meaningful improvements in respiratory-related quality of life and lung function, as well as improved CFTR function, changes that were durable over 24 weeks and superior to those seen with tezacaftor plus ivacaftor in this patient population., Funding: Vertex Pharmaceuticals., Competing Interests: Declaration of interests SS received personal fees from Proteostasis Therapeutics, Novartis Pharma, Vertex Pharmaceuticals, Chiesi, and Teva outside of the submitted work; and grants from Galapagos, Proteostasis Therapeutics, Celtaxsys, Flatley, Vertex Pharmaceuticals, Teva, Chiesi, Boehringer Ingelheim, Corbus Pharmaceuticals, and Ionis Pharmaceuticals outside of the submitted work. EFM received personal fees and grants from Vertex Pharmaceuticals during the conduct of the study; personal fees from Roche Pharmaceuticals, Insmed, and Janssen Pharmaceuticals; and other financial support from A Menarini outside of the submitted work. DGD received non-financial support from Vertex Pharmaceuticals during the conduct of the study; personal fees from Vertex Pharmaceuticals, Proteostasis, and Chiesi; and grants from Chiesi outside of the submitted work. JD received advisory board and speaker fees from Vertex Pharmaceuticals outside of the submitted work. EVB received institutional grants from Vertex Pharmaceuticals for the submitted work; and institutional grants from Vertex Pharmaceuticals, Galapagos, and Abbvie for other cystic fibrosis-related trials. MAM received personal fees from Vertex Pharmaceuticals during the conduct of the study; grants from Vertex Pharmaceuticals; and personal fees from Boehringer Ingelheim, Arrowhead Pharmaceuticals, Vertex Pharmaceuticals, Santhera, Galapagos, Sterna Biologicals, Enterprise Therapeutics, Kither Biotech, and Antabio outside of the submitted work. ET received grants and non-financial support from Vertex Pharmaceuticals during the conduct of the study; grants from Abbvie, Boehringer Ingelheim, Bayer, Spyryx, Horizon, Corbus, and Celtaxis; personal fees from Proteostasis and Horizon; and non-financial support from Proteostasis and Spyryx outside of the submitted work. CEW received institutional grants from Vertex Pharmaceuticals during the conduct of the study; grants from Novo Nordisk outside of the submitted work; and personal fees from Vertex Pharmaceuticals, Boehringer Ingelheim, Novartis, DKBmed, Gilead, and In Vivo Academy outside of the submitted work. DWal and SMM have pending patents for methods of treatment for cystic fibrosis, pharmaceutical compositions for treatment of cystic fibrosis, compositions and methods for treatment of cystic fibrosis, and crystalline forms and compositions of CFTR modulators. DWal and SMM have issued patents for crystalline forms and compositions of CFTR modulators. NA, BGB, CH, APL, YL, SMM, ST, JY, and DWal are employees of Vertex Pharmaceuticals and might own stock or stock options in the company. GM and DWat declare no competing interests., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Background: Elexacaftor-tezacaftor-ivacaftor is a small-molecule cystic fibrosis transmembrane conductance regulator (CFTR) modulator regimen shown to be efficacious in patients with at least one Phe508del allele, which indicates that this combination can modulate a single Phe508del allele. In patients whose other CFTR allele contains a gating or residual function mutation that is already effectively treated with previous CFTR modulators (ivacaftor or tezacaftor-ivacaftor), the potential for additional benefit from restoring Phe508del CFTR protein function is unclear., Methods: We conducted a phase 3, double-blind, randomized, active-controlled trial involving patients 12 years of age or older with cystic fibrosis and Phe508del -gating or Phe508del -residual function genotypes. After a 4-week run-in period with ivacaftor or tezacaftor-ivacaftor, patients were randomly assigned to receive elexacaftor-tezacaftor-ivacaftor or active control for 8 weeks. The primary end point was the absolute change in the percentage of predicted forced expiratory volume in 1 second (FEV 1 ) from baseline through week 8 in the elexacaftor-tezacaftor-ivacaftor group., Results: After the run-in period, 132 patients received elexacaftor-tezacaftor-ivacaftor and 126 received active control. Elexacaftor-tezacaftor-ivacaftor resulted in a percentage of predicted FEV 1 that was higher by 3.7 percentage points (95% confidence interval [CI], 2.8 to 4.6) relative to baseline and higher by 3.5 percentage points (95% CI, 2.2 to 4.7) relative to active control and a sweat chloride concentration that was lower by 22.3 mmol per liter (95% CI, 20.2 to 24.5) relative to baseline and lower by 23.1 mmol per liter (95% CI, 20.1 to 26.1) relative to active control (P<0.001 for all comparisons). The change from baseline in the Cystic Fibrosis Questionnaire-Revised respiratory domain score (range, 0 to 100, with higher scores indicating better quality of life) with elexacaftor-tezacaftor-ivacaftor was 10.3 points (95% CI, 8.0 to 12.7) and with active control was 1.6 points (95% CI, -0.8 to 4.1). The incidence of adverse events was similar in the two groups; adverse events led to treatment discontinuation in one patient (elevated aminotransferase level) in the elexacaftor-tezacaftor-ivacaftor group and in two patients (anxiety or depression and pulmonary exacerbation) in the active control group., Conclusions: Elexacaftor-tezacaftor-ivacaftor was efficacious and safe in patients with Phe508del -gating or Phe508del -residual function genotypes and conferred additional benefit relative to previous CFTR modulators. (Funded by Vertex Pharmaceuticals; VX18-445-104 ClinicalTrials.gov number, NCT04058353.)., (Copyright © 2021 Massachusetts Medical Society.)

Rationale: Elexacaftor/tezacaftor/ivacaftor (ELX/TEZ/IVA) was shown to be efficacious and safe in patients ≥12 years of age with cystic fibrosis and at least one F508del-CFTR (cystic fibrosis transmembrane conductance regulator) allele, but it has not been evaluated in children <12 years of age. Objectives: To assess the safety, pharmacokinetics, and efficacy of ELX/TEZ/IVA in children 6 through 11 years of age with F508del -minimal function or F508del - F508del genotypes. Methods: In this 24-week open-label phase 3 study, children ( N  = 66) weighing <30 kg received 50% of the ELX/TEZ/IVA adult daily dose (ELX 100 mg once daily, TEZ 50 mg once daily, and IVA 75 mg every 12 h) whereas children weighing ⩾30 kg received the full adult daily dose (ELX 200 mg once daily, TEZ 100 mg once daily, and IVA 150 mg every 12 h). Measurements and Main Results: The primary endpoint was safety and tolerability. The safety and pharmacokinetic profiles of ELX/TEZ/IVA were generally consistent with those observed in older patients. The most commonly reported adverse events included cough, headache, and pyrexia; in most of the children who had adverse events, these were mild or moderate in severity. Through Week 24, ELX/TEZ/IVA treatment improved the percentage of predicted FEV 1 (10.2 percentage points; 95% confidence interval [CI], 7.9 to 12.6), Cystic Fibrosis Questionnaire-Revised respiratory domain score (7.0 points; 95% CI, 4.7 to 9.2), lung clearance index 2.5 (-1.71 units; 95% CI, -2.11 to -1.30), and sweat chloride (-60.9 mmol/L; 95% CI, -63.7 to -58.2); body mass index-for-age z -score increased over the 24-week treatment period when compared with the pretreatment baseline. Conclusions: Our results show ELX/TEZ/IVA is safe and efficacious in children 6 through 11 years of age with at least one F508del-CFTR allele, supporting its use in this patient population. Clinical trial registered with www.clinicaltrials.gov (NCT03691779).

Background: Chronic infection and concomitant airway inflammation is the leading cause of morbidity and mortality for people living with cystic fibrosis (CF). Although chronic infection in CF is undeniably polymicrobial, involving a lung microbiota, infection surveillance and control approaches remain underpinned by classical aerobic culture-based microbiology. How to use microbiomics to direct clinical management of CF airway infections remains a crucial challenge. A pivotal step towards leveraging microbiome approaches in CF clinical care is to understand the ecology of the CF lung microbiome and identify ecological patterns of CF microbiota across a wide spectrum of lung disease. Assessing sputum samples from 299 patients attending 13 CF centres in Europe and the USA, we determined whether the emerging relationship of decreasing microbiota diversity with worsening lung function could be considered a generalised pattern of CF lung microbiota and explored its potential as an informative indicator of lung disease state in CF., Results: We tested and found decreasing microbiota diversity with a reduction in lung function to be a significant ecological pattern. Moreover, the loss of diversity was accompanied by an increase in microbiota dominance. Subsequently, we stratified patients into lung disease categories of increasing disease severity to further investigate relationships between microbiota characteristics and lung function, and the factors contributing to microbiota variance. Core taxa group composition became highly conserved within the severe disease category, while the rarer satellite taxa underpinned the high variability observed in the microbiota diversity. Further, the lung microbiota of individual patient were increasingly dominated by recognised CF pathogens as lung function decreased. Conversely, other bacteria, especially obligate anaerobes, increasingly dominated in those with better lung function. Ordination analyses revealed lung function and antibiotics to be main explanators of compositional variance in the microbiota and the core and satellite taxa. Biogeography was found to influence acquisition of the rarer satellite taxa., Conclusions: Our findings demonstrate that microbiota diversity and dominance, as well as the identity of the dominant bacterial species, in combination with measures of lung function, can be used as informative indicators of disease state in CF. Video Abstract.

Background: Cystic fibrosis transmembrane conductance regulator (CFTR) modulators correct the basic defect caused by CFTR mutations. Improvements in health outcomes have been achieved with the combination of a CFTR corrector and potentiator in people with cystic fibrosis homozygous for the F508del mutation. The addition of elexacaftor (VX-445), a next-generation CFTR corrector, to tezacaftor plus ivacaftor further improved F508del-CFTR function and clinical outcomes in a phase 2 study in people with cystic fibrosis homozygous for the F508del mutation., Methods: This phase 3, multicentre, randomised, double-blind, active-controlled trial of elexacaftor in combination with tezacaftor plus ivacaftor was done at 44 sites in four countries. Eligible participants were those with cystic fibrosis homozygous for the F508del mutation, aged 12 years or older with stable disease, and with a percentage predicted forced expiratory volume in 1 s (ppFEV 1 ) of 40-90%, inclusive. After a 4-week tezacaftor plus ivacaftor run-in period, participants were randomly assigned (1:1) to 4 weeks of elexacaftor 200 mg orally once daily plus tezacaftor 100 mg orally once daily plus ivacaftor 150 mg orally every 12 h versus tezacaftor 100 mg orally once daily plus ivacaftor 150 mg orally every 12 h alone. The primary outcome was the absolute change from baseline (measured at the end of the tezacaftor plus ivacaftor run-in) in ppFEV 1 at week 4. Key secondary outcomes were absolute change in sweat chloride and Cystic Fibrosis Questionnaire-Revised respiratory domain (CFQ-R RD) score. This study is registered with ClinicalTrials.gov, NCT03525548., Findings: Between Aug 3 and Dec 28, 2018, 113 participants were enrolled. Following the run-in, 107 participants were randomly assigned (55 in the elexacaftor plus tezacaftor plus ivacaftor group and 52 in the tezacaftor plus ivacaftor group) and completed the 4-week treatment period. The elexacaftor plus tezacaftor plus ivacaftor group had improvements in the primary outcome of ppFEV 1 (least squares mean [LSM] treatment difference of 10·0 percentage points [95% CI 7·4 to 12·6], p<0·0001) and the key secondary outcomes of sweat chloride concentration (LSM treatment difference -45·1 mmol/L [95% CI -50·1 to -40·1], p<0·0001), and CFQ-R RD score (LSM treatment difference 17·4 points [95% CI 11·8 to 23·0], p<0·0001) compared with the tezacaftor plus ivacaftor group. The triple combination regimen was well tolerated, with no discontinuations. Most adverse events were mild or moderate; serious adverse events occurred in two (4%) participants receiving elexacaftor plus tezacaftor plus ivacaftor and in one (2%) receiving tezacaftor plus ivacaftor., Interpretation: Elexacaftor plus tezacaftor plus ivacaftor provided clinically robust benefit compared with tezacaftor plus ivacaftor alone, with a favourable safety profile, and shows the potential to lead to transformative improvements in the lives of people with cystic fibrosis who are homozygous for the F508del mutation., Funding: Vertex Pharmaceuticals., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Background: Cystic fibrosis is caused by mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) protein, and nearly 90% of patients have at least one copy of the Phe508del CFTR mutation. In a phase 2 trial involving patients who were heterozygous for the Phe508del CFTR mutation and a minimal-function mutation (Phe508del-minimal function genotype), the next-generation CFTR corrector elexacaftor, in combination with tezacaftor and ivacaftor, improved Phe508del CFTR function and clinical outcomes., Methods: We conducted a phase 3, randomized, double-blind, placebo-controlled trial to confirm the efficacy and safety of elexacaftor-tezacaftor-ivacaftor in patients 12 years of age or older with cystic fibrosis with Phe508del-minimal function genotypes. Patients were randomly assigned to receive elexacaftor-tezacaftor-ivacaftor or placebo for 24 weeks. The primary end point was absolute change from baseline in percentage of predicted forced expiratory volume in 1 second (FEV 1 ) at week 4., Results: A total of 403 patients underwent randomization and received at least one dose of active treatment or placebo. Elexacaftor-tezacaftor-ivacaftor, relative to placebo, resulted in a percentage of predicted FEV 1 that was 13.8 points higher at 4 weeks and 14.3 points higher through 24 weeks, a rate of pulmonary exacerbations that was 63% lower, a respiratory domain score on the Cystic Fibrosis Questionnaire-Revised (range, 0 to 100, with higher scores indicating a higher patient-reported quality of life with regard to respiratory symptoms; minimum clinically important difference, 4 points) that was 20.2 points higher, and a sweat chloride concentration that was 41.8 mmol per liter lower (P<0.001 for all comparisons). Elexacaftor-tezacaftor-ivacaftor was generally safe and had an acceptable side-effect profile. Most patients had adverse events that were mild or moderate. Adverse events leading to discontinuation of the trial regimen occurred in 1% of the patients in the elexacaftor-tezacaftor-ivacaftor group., Conclusions: Elexacaftor-tezacaftor-ivacaftor was efficacious in patients with cystic fibrosis with Phe508del-minimal function genotypes, in whom previous CFTR modulator regimens were ineffective. (Funded by Vertex Pharmaceuticals; VX17-445-102 ClinicalTrials.gov number, NCT03525444.)., (Copyright © 2019 Massachusetts Medical Society.)

Background: Despite the significant impact of chronic symptoms on quality of life with cystic fibrosis (CF), the role of palliative care in management of this disease is not well defined. The coping, goal assessment, and relief from evolving CF symptoms (CF-CARES) model is a primary palliative care intervention designed to provide chronic symptom management at all stages of the disease. The goal of this pilot study was to estimate the effectiveness of the CF-CARES intervention on improving chronic symptoms and quality of life for people living with CF., Methods: A structured assessment was used to guide referral to supportive services intended to address burdensome symptoms. Follow-up assessments were performed approximately 3 and 6 months later. Longitudinal regression analyses of changes in symptoms and quality of life were performed for all participants regardless of utilization of supportive services. Subgroup analyses were performed for subjects participating in mental health and alternative health services., Results: Forty-one subjects completed assessment and referral processes. The mean number of CF-associated symptoms decreased over time, as did respiratory symptom-related distress and depressive symptoms. Subjects utilizing alternative health services reported less psychological distress at follow-up. Among subjects with severe disease, mental health, and quality of life improved, especially for those using mental health services., Conclusions: The CF-CARES model resulted in significant mental health and quality-of-life benefits, suggesting the value of integrating symptom management interventions into routine CF care. Moreover, mental health services can play a key role in CF-specific primary palliative care, especially for those with advanced disease., (© 2019 Wiley Periodicals, Inc.)

Background: Advance care planning (ACP) is recommended for people with cystic fibrosis (CF), yet guidance for optimal implementation is lacking., Objective: To assess ACP-related thoughts, comfort level, and preferences among people with CF to guide evidence-based routine implementation of ACP in the CF clinic., Design: A cross-sectional survey assessed ACP-related experiences and preferences., Subjects: Thirty-eight adolescents and adults with CF from an urban CF center., Results: Few subjects reported talking to their CF team about ACP care preferences (5%) or completing advance directives detailing desired medical treatments (11%). However, most participants worried about living with advanced disease (84%) and felt comfortable discussing ACP preferences with CF providers (92%). Subjects largely preferred that ACP conversations occur when they are generally healthy, in the outpatient setting, and with any familiar CF team member. Disease severity was not associated with frequency of worry about living with advanced disease, comfort level with ACP discussions, or ACP setting preferences., Conclusions: People with CF worry about advanced disease and feel comfortable discussing ACP, but need more guidance to understand and document ACP choices. CF patient experiences and preferences support implementation of an early, active approach to ACP for people with CF.

Background: The next-generation cystic fibrosis transmembrane conductance regulator (CFTR) corrector VX-659, in triple combination with tezacaftor and ivacaftor (VX-659-tezacaftor-ivacaftor), was developed to restore the function of Phe508del CFTR protein in patients with cystic fibrosis., Methods: We evaluated the effects of VX-659-tezacaftor-ivacaftor on the processing, trafficking, and function of Phe508del CFTR protein using human bronchial epithelial cells. A range of oral VX-659-tezacaftor-ivacaftor doses in triple combination were then evaluated in randomized, controlled, double-blind, multicenter trials involving patients with cystic fibrosis who were heterozygous for the Phe508del CFTR mutation and a minimal-function CFTR mutation (Phe508del-MF genotypes) or homozygous for the Phe508del CFTR mutation (Phe508del-Phe508del genotype). The primary end points were safety and the absolute change from baseline in the percentage of predicted forced expiratory volume in 1 second (FEV 1 )., Results: VX-659-tezacaftor-ivacaftor significantly improved the processing and trafficking of Phe508del CFTR protein as well as chloride transport in vitro. In patients, VX-659-tezacaftor-ivacaftor had an acceptable safety and side-effect profile. Most adverse events were mild or moderate. VX-659-tezacaftor-ivacaftor resulted in significant mean increases in the percentage of predicted FEV 1 through day 29 (P<0.001) of up to 13.3 points in patients with Phe508del-MF genotypes; in patients with the Phe508del-Phe508del genotype already receiving tezacaftor-ivacaftor, adding VX-659 resulted in a further 9.7-point increase in the percentage of predicted FEV 1 . The sweat chloride concentrations and scores on the respiratory domain of the Cystic Fibrosis Questionnaire-Revised improved in both patient populations., Conclusions: Robust in vitro activity of VX-659-tezacaftor-ivacaftor targeting Phe508del CFTR protein translated into improvements for patients with Phe508del-MF or Phe508del-Phe508del genotypes. VX-659 triple-combination regimens have the potential to treat the underlying cause of disease in approximately 90% of patients with cystic fibrosis. (Funded by Vertex Pharmaceuticals; VX16-659-101 and VX16-659-001 ClinicalTrials.gov numbers, NCT03224351 and NCT03029455 .).

Background: VX-445 is a next-generation cystic fibrosis transmembrane conductance regulator (CFTR) corrector designed to restore Phe508del CFTR protein function in patients with cystic fibrosis when administered with tezacaftor and ivacaftor (VX-445-tezacaftor-ivacaftor)., Methods: We evaluated the effects of VX-445-tezacaftor-ivacaftor on Phe508del CFTR protein processing, trafficking, and chloride transport in human bronchial epithelial cells. On the basis of in vitro activity, a randomized, placebo-controlled, double-blind, dose-ranging, phase 2 trial was conducted to evaluate oral VX-445-tezacaftor-ivacaftor in patients heterozygous for the Phe508del CFTR mutation and a minimal-function mutation (Phe508del-MF) and in patients homozygous for the Phe508del CFTR mutation (Phe508del-Phe508del) after tezacaftor-ivacaftor run-in. Primary end points were safety and absolute change in percentage of predicted forced expiratory volume in 1 second (FEV 1 ) from baseline., Results: In vitro, VX-445-tezacaftor-ivacaftor significantly improved Phe508del CFTR protein processing, trafficking, and chloride transport to a greater extent than any two of these agents in dual combination. In patients with cystic fibrosis, VX-445-tezacaftor-ivacaftor had an acceptable safety and side-effect profile. Most adverse events were mild or moderate. The treatment also resulted in an increased percentage of predicted FEV 1 of up to 13.8 points in the Phe508del-MF group (P<0.001). In patients in the Phe508del-Phe508del group, who were already receiving tezacaftor-ivacaftor, the addition of VX-445 resulted in an 11.0-point increase in the percentage of predicted FEV 1 (P<0.001). In both groups, there was a decrease in sweat chloride concentrations and improvement in the respiratory domain score on the Cystic Fibrosis Questionnaire-Revised., Conclusions: The use of VX-445-tezacaftor-ivacaftor to target Phe508del CFTR protein resulted in increased CFTR function in vitro and translated to improvements in patients with cystic fibrosis with one or two Phe508del alleles. This approach has the potential to treat the underlying cause of cystic fibrosis in approximately 90% of patients. (Funded by Vertex Pharmaceuticals; VX16-445-001 ClinicalTrials.gov number, NCT03227471 ; and EudraCT number, 2017-000797-11 .).

Background: Current palliative care tools do not address distressing chronic symptoms that are most relevant to cystic fibrosis., Methods: A CF-specific structured assessment based on a primary palliative care framework was administered to 41 adolescents and adults with CF. Descriptive and correlational analyses were conducted., Results: Patients reported numerous physical and psychological symptoms (mean of 10 per patient), with psychological symptoms rated as more distressing. Anxiety (34%) and depression (44%) were prevalent and correlated with distress attributable to physical symptoms and difficulty with CF self-management, but did not correlate with disease severity., Conclusions: Individuals with CF, regardless of disease severity, face challenges managing symptom burden. Frequently reported symptoms are not consistently associated with distress, suggesting the importance of individualized evaluation. The CF-CARES (Coping, goal Assessment, and Relief from Evolving CF Symptoms) primary palliative care assessment model provides a framework for patients experiencing chronic symptoms to explore interventional options with their clinicians., (Copyright © 2017 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.)

Background: Primary palliative care refers to basic skills that all healthcare providers can employ to improve quality of life for patients at any stage of disease. Training in these core skills is not commonly provided to clinicians caring for cystic fibrosis (CF) patients. The objective of this study was to assess change in comfort with core skills among care team members after participation in CF-specific palliative care training focused on management of burdensome symptoms and difficult conversations., Methods: A qualitative needs assessment was performed to inform the development of an 18-hour curriculum tailored to the chronicity and complexity of CF care. A 32-question pre- and post-course survey assessed CF provider comfort with the targeted palliative care skills in 5 domains using a 5-point Likert scale (1=very uncomfortable, 3=neutral, 5=very comfortable)., Results: Among course participants (n=16), mean overall comfort score increased by 0.9, from 3 (neutral) to 3.9 (comfortable) (p<0.001). Mean comfort level increased significantly (range 0.8 to 1.4) in each skill domain: use of supportive care resources, pain management, non-pain symptom management, communication, and psychosocial skills., Conclusions: CF-specific palliative care training was well received by participants and significantly improved self-assessed comfort with core skills., (Copyright © 2015 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.)

Cystic fibrosis (CF) airway disease is characterized by Pseudomonas aeruginosa infection and recruitment of neutrophil granulocytes. Neutrophil granule components (myeloperoxidase (MPO), human neutrophil elastase (HNE)), extracellular DNA and P. aeruginosa can all be found in the CF respiratory tract and have all been associated with worsening CF lung function. Pseudomonas-induced formation of neutrophil extracellular traps (NETs) offers a likely mechanism for release of MPO, HNE and DNA from neutrophils. NETs are composed of a DNA backbone decorated with granule proteins like MPO and HNE. Here we sought to examine whether CF clinical isolates of Pseudomonas are capable of inducing NET release from human neutrophil granulocytes. We used two methods to quantify NETs. We modified a previously employed ELISA that detects MPO-DNA complexes and established a new HNE-DNA ELISA. We show that these methods reliably quantify MPO-DNA and HNE-DNA complexes, measures of NET formation. We have found that CF isolates of P. aeruginosa stimulate robust respiratory burst and NET release in human neutrophils. By comparing paired "early" and "late" bacterial isolates obtained from the same CF patient we have found that early isolates induced significantly more NET release than late isolates. Our data support that Pseudomonas-induced NET release represents an important mechanism for release of neutrophil-derived CF inflammatory mediators, and confirm that decreased induction of NET formation is required for long-term adaptation of P. aeruginosa to CF airways., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Cystic fibrosis (CF) airways are characterized by bacterial infections, excess mucus production, and robust neutrophil recruitment. The main CF airway pathogen is Pseudomonas aeruginosa. Neutrophils are not capable of clearing the infection. Neutrophil primary granule components, myeloperoxidase (MPO) and human neutrophil elastase (HNE), are inflammatory markers in CF airways, and their increased levels are associated with poor lung function. Identifying the mechanism of MPO and HNE release from neutrophils is of high clinical relevance for CF. In this article, we show that human neutrophils release large amounts of neutrophil extracellular traps (NETs) in the presence of P. aeruginosa. Bacteria are entangled in NETs and colocalize with extracellular DNA. MPO, HNE, and citrullinated histone H4 are all associated with DNA in Pseudomonas-triggered NETs. Both laboratory standard strains and CF isolates of P. aeruginosa induce DNA, MPO, and HNE release from human neutrophils. The increase in peroxidase activity of neutrophil supernatants after Pseudomonas exposure indicates that enzymatically active MPO is released. P. aeruginosa induces a robust respiratory burst in neutrophils that is required for extracellular DNA release. Inhibition of the cytoskeleton prevents Pseudomonas-initiated superoxide production and DNA release. NADPH oxidase inhibition suppresses Pseudomonas-induced release of active MPO and HNE. Blocking MEK/ERK signaling results in only minimal inhibition of DNA release induced by Pseudomonas. Our data describe in vitro details of DNA, MPO, and HNE release from neutrophils activated by P. aeruginosa. We propose that Pseudomonas-induced NET formation is an important mechanism contributing to inflammatory conditions characteristic of CF airways.

Rationale: Recent studies of inhaled tobramycin in subjects with cystic fibrosis (CF) find less clinical improvement than previously observed. Nonhuman data suggest that in some strains of Pseudomonas aeruginosa, azithromycin can antagonize tobramycin., Objectives: We tested the hypothesis that concomitant azithromycin use correlates with less improvement in key outcome measures in subjects receiving inhaled tobramycin while not affecting those receiving a comparative, nonaminoglycoside inhaled antibiotic., Methods: We studied a cohort of 263 subjects with CF enrolled in a recent clinical trial comparing inhaled tobramycin with aztreonam lysine. We performed a secondary analysis to examine key clinical and microbiologic outcomes based on concomitant, chronic azithromycin use at enrollment., Measurements and Main Results: The cohort randomized to inhaled tobramycin and reporting azithromycin use showed a significant decrease in the percent predicted FEV1 after one and three courses of inhaled tobramycin when compared with those not reporting azithromycin use (28 d: -0.51 vs. 3.43%, P < 0.01; 140 d: -1.87 vs. 6.07%, P < 0.01). Combined azithromycin and inhaled tobramycin use was also associated with earlier need for additional antibiotics, lesser improvement in disease-related quality of life, and a trend toward less reduction in sputum P. aeruginosa density. Subjects randomized to inhaled aztreonam lysine had significantly greater improvement in these outcome measures, which were unaffected by concomitant azithromycin use. Outcomes in those not using azithromycin who received inhaled tobramycin were not significantly different from subjects receiving aztreonam lysine. Azithromycin also antagonized tobramycin but not aztreonam lysine in 40% of P. aeruginosa clinical isolates tested in vitro., Conclusions: Oral azithromycin may antagonize the therapeutic benefits of inhaled tobramycin in subjects with CF with P. aeruginosa airway infection.

Strains of Pseudomonas aeruginosa (PA) isolated from the airways of cystic fibrosis patients constitutively add palmitate to lipid A, the membrane anchor of lipopolysaccharide. The PhoPQ regulated enzyme PagP is responsible for the transfer of palmitate from outer membrane phospholipids to lipid A. This enzyme had previously been identified in many pathogenic Gram-negative bacteria, but in PA had remained elusive, despite abundant evidence that its lipid A contains palmitate. Using a combined genetic and biochemical approach, we identified PA1343 as the PA gene encoding PagP. Although PA1343 lacks obvious primary structural similarity with known PagP enzymes, the β-barrel tertiary structure with an interior hydrocarbon ruler appears to be conserved. PA PagP transfers palmitate to the 3' position of lipid A, in contrast to the 2 position seen with the enterobacterial PagP. Palmitoylated PA lipid A alters host innate immune responses, including increased resistance to some antimicrobial peptides and an elevated pro-inflammatory response, consistent with the synthesis of a hexa-acylated structure preferentially recognized by the TLR4/MD2 complex. Palmitoylation commonly confers resistance to cationic antimicrobial peptides, however, increased cytokine production resulting in inflammation is not seen with other palmitoylated lipid A, indicating a unique role for this modification in PA pathogenesis., (© 2013 John Wiley & Sons Ltd.)

Pseudomonas aeruginosa can develop resistance to polymyxin and other cationic antimicrobial peptides. Previous work has shown that mutations in the PmrAB and PhoPQ regulatory systems can confer low to moderate levels of colistin (polymyxin E) resistance in laboratory strains and clinical isolates of this organism (MICs of 8 to 64 mg/liter). To explore the role of PmrAB in high-level clinical polymyxin resistance, P. aeruginosa isolates from chronically colistin-treated cystic fibrosis patients, most with colistin MICs of >512 mg/liter, were analyzed. These cystic fibrosis isolates contained probable gain-of-function pmrB alleles that conferred polymyxin resistance to strains with a wild-type or pmrAB deletion background. Double mutant pmrB alleles that contained mutations in both the periplasmic and dimerization-phosphotransferase domains markedly augmented polymyxin resistance. Expression of mutant pmrB alleles induced transcription from the promoter of the arnB operon and stimulated addition of 4-amino-l-arabinose to lipid A, consistent with the known role of this lipid A modification in polymyxin resistance. For some highly polymyxin-resistant clinical isolates, repeated passage without antibiotic selection pressure resulted in loss of resistance, suggesting that secondary suppressors occur at a relatively high frequency and account for the instability of this phenotype. These results indicate that pmrB gain-of-function mutations can contribute to high-level polymyxin resistance in clinical strains of P. aeruginosa.

Pseudomonas aeruginosa can develop resistance to polymyxin and other cationic antimicrobial peptides. Previous work has shown that mutations in the PmrAB and PhoPQ regulatory systems can confer low to moderate levels of polymyxin resistance (MICs of 8 to 64 mg/liter) in laboratory and clinical strains of this organism. To explore the role of PhoPQ in high-level clinical polymyxin resistance, P. aeruginosa strains with colistin MICs > 512 mg/liter that had been isolated from cystic fibrosis patients treated with inhaled colistin (polymyxin E) were analyzed. Probable loss-of-function phoQ alleles found in these cystic fibrosis strains conferred resistance to polymyxin. Partial and complete suppressor mutations in phoP were identified in some cystic fibrosis strains with resistance-conferring phoQ mutations, suggesting that additional loci can be involved in polymyxin resistance in P. aeruginosa. Disruption of chromosomal phoQ in the presence of an intact phoP allele stimulated 4-amino-l-arabinose addition to lipid A and induced transcription from the promoter of the pmrH (arnB) operon, consistent with the known role of this lipid A modification in polymyxin resistance. These results indicate that phoQ loss-of-function mutations can contribute to high-level polymyxin resistance in clinical strains of P. aeruginosa.

Rationale: In cystic fibrosis (CF), conventional antibiotic susceptibility results correlate poorly with clinical outcomes. We hypothesized that biofilm testing would more accurately reflect the susceptibilities of bacteria infecting CF airways., Methods: A multicenter randomized pilot trial was conducted to assess the efficacy and safety of using biofilm susceptibility testing of Pseudomonas aeruginosa sputum isolates to guide antibiotic regimens for chronic airway infections in clinically stable adolescent and adult CF patients. Thirty-nine participants were randomized to biofilm or conventional treatment groups; 14-day courses of two antibiotics were selected according to an activity-based algorithm using the corresponding susceptibility results., Results: Of the agents tested, meropenem was most active against biofilm-grown bacteria, and was included in regimens for about half of each study group. For 19 of 39 randomized participants, randomization to the other study group would not have changed the antibiotic classes of the assigned regimen. Study groups were comparable at baseline, and had similar mean decreases in bacterial density, measured in log(10) colony forming units per gram of sputum (biofilm, -2.94 [SD 2.83] vs. conventional, -3.27 [SD 3.09]), and mean increases in forced expiratory volume in 1 sec, measured in liters (0.18 [SD 0.20] vs. 0.12 [SD 0.22])., Conclusions: In this pilot study, antibiotic regimens based on biofilm testing did not differ significantly from regimens based on conventional testing in terms of microbiological and clinical responses. The predictive value of biofilm testing may nonetheless warrant evaluation in an adequately powered clinical trial in younger CF patients or those experiencing acute pulmonary exacerbation., (Copyright © 2011 Wiley-Liss, Inc.)

The inability of neutrophils to eradicate Pseudomonas aeruginosa within the cystic fibrosis (CF) airway eventually results in chronic infection by the bacteria in nearly 80 percent of patients. Phagocytic killing of P. aeruginosa by CF neutrophils is impaired due to decreased cystic fibrosis transmembrane conductance regulator (CFTR) function and virulence factors acquired by the bacteria. Recently, neutrophil extracellular traps (NETs), extracellular structures composed of neutrophil chromatin complexed with granule contents, were identified as an alternative mechanism of pathogen killing. The hypothesis that NET-mediated killing of P. aeruginosa is impaired in the context of the CF airway was tested. P. aeruginosa induced NET formation by neutrophils from healthy donors in a bacterial density dependent fashion. When maintained in suspension through continuous rotation, P. aeruginosa became physically associated with NETs. Under these conditions, NETs were the predominant mechanism of killing, across a wide range of bacterial densities. Peripheral blood neutrophils isolated from CF patients demonstrated no impairment in NET formation or function against P. aeruginosa. However, isogenic clinical isolates of P. aeruginosa obtained from CF patients early and later in the course of infection demonstrated an acquired capacity to withstand NET-mediated killing in 8 of 9 isolates tested. This resistance correlated with development of the mucoid phenotype, but was not a direct result of the excess alginate production that is characteristic of mucoidy. Together, these results demonstrate that neutrophils can kill P. aeruginosa via NETs, and in vitro this response is most effective under non-stationary conditions with a low ratio of bacteria to neutrophils. NET-mediated killing is independent of CFTR function or bacterial opsonization. Failure of this response in the context of the CF airway may occur, in part, due to an acquired resistance against NET-mediated killing by CF strains of P. aeruginosa.

Pseudomonas aeruginosa (PA) is a ubiquitous environmental Gram-negative bacterium found in soil and water. This opportunistic pathogen can cause infections in individuals with impaired phagocytic function, such as those with burns, exposure to chemotherapy, or cystic fibrosis (CF). PA infects the lungs of most individuals with CF, and is associated with severe progressive pulmonary disease that is the major cause of premature death in this disorder. The specific adaptations of PA to the CF airway responsible for bacterial persistence and antibiotic tolerance are not completely understood but may include increased alginate production (i.e., mucoid phenotype), biofilm formation, and specific lipid A modifications. During adaptation to the CF airway, PA synthesizes a variety of lipid A structures that alter host innate immune responses and promote bacterial persistence and chronic infection. The synthesis of specific lipid A structures is attributable to bacterial enzymes that: (1) remove the 3OH-C10:0 acyl chain from the 3-position (PagL); (2) add a C16:0 acyl chain to the 3OH-C10:0 chain at the 3'-position (PagP); (3) add C12:0 and 2OH-C12:0 acyl chains to the 3OH-C12:0 chains at the 2- and 2'-positions (HtrB and LpxO); and (4) add aminoarabinose to phosphate groups at the 1- and 4'-positions (PmrH, PmrF, PmrI, PmrJ, PmrK, and PmrE). These lipid A modifications represent an essential aspect of PA adaptation to the CF airway.

Cystic fibrosis transmembrane conductance regulator-related disorders encompass a disease spectrum from focal male reproductive tract involvement in congenital absence of the vas deferens to multiorgan involvement in classic cystic fibrosis. The reproductive, gastrointestinal, and exocrine manifestations of cystic fibrosis transmembrane conductance regulator deficiency are correlated with CFTR genotype, whereas the respiratory manifestations that are the main cause of morbidity and mortality in cystic fibrosis are less predictable. Molecular genetic testing of CFTR has led to new diagnostic strategies and will enable targeting of molecular therapies now in development. Older diagnostic methods that measure sweat chloride and nasal potential difference nonetheless remain important because of their sensitivity and specificity. In addition, the measurement of immunoreactive trypsinogen and the genotyping of CFTR alleles are key to newborn screening programs because of low cost. The multiorgan nature of cystic fibrosis leads to a heavy burden of care, thus therapeutic regimens are tailored to the specific manifestations present in each patient. The variability of cystic fibrosis lung disease and the variable expressivity of mild CFTR alleles complicate genetic counseling for this autosomal recessive disorder. Widespread implementation of newborn screening programs among populations with significant cystic fibrosis mutation carrier frequencies is expected to result in increasing demands on genetic counseling resources.

Rationale: Antibiotic inhalation has become widely accepted as a standard treatment for cystic fibrosis (CF) airway infection. We assessed the prevalence and context of inhaled antibiotic use in the North American CF population. Our working hypothesis was that a shift from acute to chronic use of inhaled antibiotics has coincided with increased prevalence of use among CF patients., Methods: Descriptive statistics were collected for 30,833 patients enrolled in the Epidemiologic Study of CF (ESCF) during 1996 through 2005. A multivariate analysis was performed on data from a subgroup of 18,021 patients enrolled in ESCF during 2003 through 2005., Results: The prevalence of inhaled antibiotic use in the North American CF population increased during 1996 through 2005 due to increased chronic use, while acute use to treat pulmonary exacerbations decreased. In 2005, 50% of CF patients used inhaled tobramycin and 9% used inhaled colistin chronically; most of the latter used both agents concurrently. Airway obstruction severity and airway infection status were predictors of inhaled antibiotic use., Conclusions: Increased chronic use and decreased acute use of inhaled antibiotics presumably reflect a shift toward more proactive management of airway infections in the North American CF population. The effects of these usage patterns on long-term clinical outcomes and emergence of antibiotic-resistant Pseudomonas aeruginosa strains warrant further study., ((c) 2008 Wiley-Liss, Inc.)

Background: Colistin resistant Pseudomonas aeruginosa have rarely been reported in cystic fibrosis (CF) patients., Methods: We performed a 17-year prospective study on colistin susceptibility and compared our findings with clinical variables., Results: The first outbreak started in 1995 and lasted 5 years. It involved 27 CF patients who had inhaled colistin twice daily for a median of 10 years. Colistin resistant isolates persisted in individual patients for a median of 75 days after colistin was withdrawn. A second outbreak started in 2004. It involved 40 patients, 17 of whom were the same as in the first outbreak. Most resistant isolates belonged to two major clones that had similar genotypes in the two outbreaks. The P. aeruginosa isolates were all non-mucoid and they appeared in a group of chronically infected patients that had been admitted to the same ward for antibiotic treatment and had been followed at the same week-days in the outpatient clinic. Patients were individually isolated to avoid cross-infection and colistin inhalation was avoided in the CF outpatient clinic and in the ward after both outbreaks. Since 2004, no further spread has been observed., Conclusion: It is important that the colistin resistant clones do not spread to non-infected patients since colistin is an important antibiotic for eradication of initial and intermittent P. aeruginosa colonisation.

Three structural features of lipid A (addition of palmitate [C16 fatty acid], addition of aminoarabinose [positively charged amino sugar residue], and retention of 3-hydroxydecanoate [3-OH C10 fatty acid]) were determined for Pseudomonas aeruginosa isolates from patients with cystic fibrosis (CF; n=86), from the environment (n=13), and from patients with other conditions (n=14). Among P. aeruginosa CF isolates, 100% had lipid A with palmitate, 24.6% with aminoarabinose, and 33.3% retained 3-hydroxydecanoate. None of the isolates from the environment or from patients with other conditions displayed these modifications. These results indicate that unique lipid A modifications occur in clinical P. aeruginosa CF isolates.

In many human infections, hosts and pathogens coexist for years or decades. Important examples include HIV, herpes viruses, tuberculosis, leprosy, and malaria. With the exception of intensively studied viral infections such as HIV/AIDs, little is known about the extent to which the clonal expansion that occurs during long-term infection by pathogens involves important genetic adaptations. We report here a detailed, whole-genome analysis of one such infection, that of a cystic fibrosis (CF) patient by the opportunistic bacterial pathogen Pseudomonas aeruginosa. The bacteria underwent numerous genetic adaptations during 8 years of infection, as evidenced by a positive-selection signal across the genome and an overwhelming signal in specific genes, several of which are mutated during the course of most CF infections. Of particular interest is our finding that virulence factors that are required for the initiation of acute infections are often selected against during chronic infections. It is apparent that the genotypes of the P. aeruginosa strains present in advanced CF infections differ systematically from those of "wild-type" P. aeruginosa and that these differences may offer new opportunities for treatment of this chronic disease.

Lipopolysaccharide (LPS) is the major surface component of gram-negative bacteria, and a component of LPS, lipid A, is recognized by the innate immune system through the Toll-like receptor 4/MD-2 complex. Pseudomonas aeruginosa, an environmental gram-negative bacterium that opportunistically infects the respiratory tracts of patients with cystic fibrosis (CF), can synthesize various structures of lipid A. Lipid A from P. aeruginosa strains isolated from infants with CF has a specific structure that includes the removal of the 3 position 3-OH C10 fatty acid. Here we demonstrate increased expression of the P. aeruginosa lipid A 3-O-deacylase (PagL) in isolates from CF infants compared to that in environmental isolates. PagL activity was increased in environmental isolates by growth in medium limited for magnesium and decreased by growth at low temperature in laboratory-adapted strains of P. aeruginosa. P. aeruginosa PagL was shown to be an outer membrane protein by isopycnic density gradient centrifugation. Heterologous expression of P. aeruginosa pagL in Salmonella enterica serovar Typhimurium and Escherichia coli resulted in removal of the 3-OH C14 fatty acid from lipid A, indicating that P. aeruginosa PagL recognizes either 3-OH C10 or 3-OH C14. Finally, deacylated lipid A species were not observed in some clinical P. aeruginosa isolates from patients with severe pulmonary disease, suggesting that loss of PagL function can occur during long-term adaptation to the CF airway.

Objectives: Increasing evidence indicates that Pseudomonas aeruginosa grows as a biofilm in the lungs of cystic fibrosis (CF) patients. In contrast, the bacterial inoculum used in conventional susceptibility testing is composed of planktonic cells. As a prelude to a clinical trial of biofilm susceptibility testing in CF, simulated antibiotic regimens based on either biofilm or conventional susceptibility testing of CF patient isolates were compared., Patients and Methods: Biofilm and conventional susceptibilities were determined for P. aeruginosa isolate sets from 40 CF patients. An algorithm was used to assign simulated regimens of two anti-pseudomonal antibiotics for each patient/susceptibility method dataset. For agents with equivalent activity, the algorithm included a drug selection hierarchy, the rationale for which was suppression of chronic infection. Substitution of an alternative hierarchy, based on treatment of acute exacerbation, was used to evaluate the robustness of the regimen assignments., Results: For both drug-ranking schemes, all 40 simulated regimens based on conventional susceptibilities included a beta-lactam antibiotic. In contrast, based on biofilm testing, only 43% of chronic regimens and 65% of acute regimens included a beta-lactam. Moreover, the conventional and biofilm regimens assigned to individual patients were discordant, with only 20% and 40% of chronic and acute regimens, respectively, consisting of drugs in the same two mechanistic classes by both methods., Conclusions: Biofilm susceptibility testing of CF P. aeruginosa isolate sets leads to different antibiotic assignments than conventional testing, with no single two-drug regimen predicted to provide optimal anti-biofilm activity against the majority of isolate sets.

Cystic fibrosis (CF) is a multiorgan disease caused by mutation of the CF transmembrane conductance regulator (CFTR) gene. Obstructive lung disease is the predominant cause of morbidity and mortality; thus, most efforts to improve outcomes are directed toward slowing or halting lung-disease progression. Current therapies, such as mucolytics, airway clearance techniques, bronchodilators, and antibiotics, aim to suppress airway inflammation and the processes that stimulate it, namely, retention and infection of mucus plaques at the airway surface. New approaches to therapy that aim to ameliorate specific CFTR mutations or mutational classes by restoring normal expression or function are being investigated. Because of its sensitivity in detecting changes associated with early airway obstruction and regional lung disease, high-resolution CT (HRCT) complements pulmonary function testing in defining disease natural history and measuring response to both conventional and experimental therapies. In this review, perspectives on the genetics and microbiology of CF provide a context for understanding the increasing importance of HRCT and other imaging techniques in assessing CF therapies.

Pandoraea is a recently classified genus primarily isolated from the sputum of cystic fibrosis patients, but its pathogenic potential is unknown. We describe a case of Pandoraea bacteremia in a 16-year-old cystic fibrosis patient associated with clinical disease, suggesting that this organism should be considered a true pathogen in susceptible patients.

Pseudomonas aeruginosa is the predominant cause of chronic airway infection in cystic fibrosis (CF). CF airway isolates are often tested for antibiotic susceptibility but are rarely eradicated by the antibiotics identified as potentially effective. The growth state of P. aeruginosa in CF airways is probably different from that exhibited under conventional susceptibility testing conditions and may represent a bacterial biofilm. Biofilm susceptibility testing methods were adapted to create an assay for implementation in a clinical microbiology laboratory. This assay gave reproducible results when examined in 300 paired determinations with 12 antimicrobial agents, with a serious error rate of 5.7%. The biofilm assay was used retrospectively to test these 12 agents against 94 isolates from 41 CF patients. The biofilm inhibitory concentrations (BICs) were much higher than the corresponding conventionally determined MICs for the beta-lactam antibiotics (median values: aztreonam, >128 microg/ml versus 4 microg/ml; ceftazidime, 128 microg/ml versus 2 microg/ml; piperacillin-tazobactam, 256 microg/ml versus 4 microg/ml; and ticarcillin-clavulanate, 512 microg/ml versus 16 microg/ml, respectively) and doxycycline (>64 microg/ml versus 16 microg/ml); and similar for meropenem (4 micro g/ml versus < or = 1 microg/ml), ciprofloxacin (0.5 microg/ml versus 1 microg/ml), and the aminoglycosides amikacin (32 microg/ml versus 16 microg/ml), gentamicin (16 microg/ml versus 8 microg/ml), and tobramycin (4 microg/ml versus 2 microg/ml). The median BIC for azithromycin was 2 microg/ml, whereas isolates were uniformly resistant when tested by standard methods. This demonstrates the feasibility of adapting biofilm susceptibility methods to the clinical microbiology laboratory and opens the way to examining whether biofilm testing might be used to select more effective antibiotic combinations for CF airway infections than methods in current use.

ObjectivesChronic endobronchial infections with Pseudomonas aeruginosa contribute to bronchiectasis and progressive loss of lung function in patients with cystic fibrosis. This study aimed to evaluate the therapeutic potential of a novel macrocyclic peptide, rhesus θ-defensin-1 (RTD-1), by characterizing its in vitro antipseudomonal activity and in vivo efficacy in a murine model of chronic Pseudomonas lung infection.MethodsAntibacterial testing of RTD-1 was performed on 41 clinical isolates of P. aeruginosa obtained from cystic fibrosis patients. MIC, MBC, time-kill and post-antibiotic effects were evaluated following CLSI-recommended methodology, but using anion-depleted Mueller-Hinton broth. RTD-1 was nebulized daily for 7 days to cystic fibrosis transmembrane conductance regulator (CFTR) F508del-homozygous mice infected using the agar bead model of chronic P. aeruginosa lung infection. In vivo activity was evaluated by change in lung bacterial burden, airway leucocytes and body weight.ResultsRTD-1 exhibited potent in vitro bactericidal activity against mucoid and non-mucoid strains of P. aeruginosa (MIC90 = 8 mg/L). Cross-resistance was not observed when tested against MDR and colistin-resistant isolates. Time-kill studies indicated very rapid, concentration-dependent bactericidal activity of RTD-1 with ≥3 log10 cfu/mL reductions at concentrations ≥4× MIC. No post-antibiotic effect was observed. In vivo, nebulized treatment with RTD-1 significantly decreased lung P. aeruginosa burden (mean difference of -1.30 log10 cfu; P = 0.0061), airway leucocytes (mean difference of -0.37 log10; P = 0.0012) and weight loss (mean difference of -12.62% at day 7; P

Rationale: The triple-combination regimen elexacaftor/tezacaftor/ivacaftor (ELX/TEZ/IVA) was shown to be safe and efficacious in children aged 6 through 11 years with cystic fibrosis and at least one F508del-CFTR allele in a phase 3, open-label, single-arm study. Objectives: To further evaluate the efficacy and safety of ELX/TEZ/IVA in children 6 through 11 years of age with cystic fibrosis heterozygous for F508del and a minimal function CFTR mutation (F/MF genotypes) in a randomized, double-blind, placebo-controlled phase 3b trial. Methods: Children were randomized to receive either ELX/TEZ/IVA (n = 60) or placebo (n = 61) during a 24-week treatment period. The dose of ELX/TEZ/IVA administered was based on weight at screening, with children <30 kg receiving ELX 100 mg once daily, TEZ 50 mg once daily, and IVA 75 mg every 12 hours, and children ⩾30 kg receiving ELX 200 mg once daily, TEZ 100 mg once daily, and IVA 150 mg every 12 hours (adult dose). Measurements and Main Results: The primary endpoint was absolute change in lung clearance index2.5 from baseline through Week 24. Children given ELX/TEZ/IVA had a mean decrease in lung clearance index2.5 of 2.29 units (95% confidence interval [CI], 1.97-2.60) compared with 0.02 units (95% CI, -0.29 to 0.34) in children given placebo (between-group treatment difference, -2.26 units; 95% CI, -2.71 to -1.81; P < 0.0001). ELX/TEZ/IVA treatment also led to improvements in the secondary endpoint of sweat chloride concentration (between-group treatment difference, -51.2 mmol/L; 95% CI, -55.3 to -47.1) and in the other endpoints of percent predicted FEV1 (between-group treatment difference, 11.0 percentage points; 95% CI, 6.9-15.1) and Cystic Fibrosis Questionnaire-Revised Respiratory domain score (between-group treatment difference, 5.5 points; 95% CI, 1.0-10.0) compared with placebo from baseline through Week 24. The most common adverse events in children receiving ELX/TEZ/IVA were headache and cough (30.0% and 23.3%, respectively); most adverse events were mild or moderate in severity. Conclusions: In this first randomized, controlled study of a cystic fibrosis transmembrane conductance regulator modulator conducted in children 6 through 11 years of age with F/MF genotypes, ELX/TEZ/IVA treatment led to significant improvements in lung function, as well as robust improvements in respiratory symptoms and cystic fibrosis transmembrane conductance regulator function. ELX/TEZ/IVA was generally safe and well tolerated in this pediatric population with no new safety findings. [ABSTRACT FROM AUTHOR]

Rationale: Elexacaftor/tezacaftor/ivacaftor (ELX/TEZ/IVA) was shown to be efficacious and safe in patients ≥12 years of age with cystic fibrosis and at least one F508del-CFTR (cystic fibrosis transmembrane conductance regulator) allele, but it has not been evaluated in children <12 years of age. Objectives: To assess the safety, pharmacokinetics, and efficacy of ELX/TEZ/IVA in children 6 through 11 years of age with F508del-minimal function or F508del-F508del genotypes. Methods: In this 24-week open-label phase 3 study, children (N = 66) weighing <30 kg received 50% of the ELX/TEZ/IVA adult daily dose (ELX 100 mg once daily, TEZ 50 mg once daily, and IVA 75 mg every 12 h) whereas children weighing ⩾30 kg received the full adult daily dose (ELX 200 mg once daily, TEZ 100 mg once daily, and IVA 150 mg every 12 h). Measurements and Main Results: The primary endpoint was safety and tolerability. The safety and pharmacokinetic profiles of ELX/TEZ/IVA were generally consistent with those observed in older patients. The most commonly reported adverse events included cough, headache, and pyrexia; in most of the children who had adverse events, these were mild or moderate in severity. Through Week 24, ELX/TEZ/IVA treatment improved the percentage of predicted FEV1 (10.2 percentage points; 95% confidence interval [CI], 7.9 to 12.6), Cystic Fibrosis Questionnaire-Revised respiratory domain score (7.0 points; 95% CI, 4.7 to 9.2), lung clearance index2.5 (-1.71 units; 95% CI, -2.11 to -1.30), and sweat chloride (-60.9 mmol/L; 95% CI, -63.7 to -58.2); body mass index-for-age z-score increased over the 24-week treatment period when compared with the pretreatment baseline. Conclusions: Our results show ELX/TEZ/IVA is safe and efficacious in children 6 through 11 years of age with at least one F508del-CFTR allele, supporting its use in this patient population. Clinical trial registered with www.clinicaltrials.gov (NCT03691779). [ABSTRACT FROM AUTHOR]

Pseudomonas aeruginosa (PA) is an opportunistic Gram-negative pathogen associated with nosocomial infections, acute infections and chronic lung infections in patients with cystic fibrosis. The ability of PA to cause infection can be attributed to its ability to adapt to a multitude of environments. Modification of the lipid A portion of lipopolysaccharide (LPS) is a vital mechanism Gram-negative pathogens use to remodel the outer membrane in response to environmental stimuli. Lipid A, the endotoxic moiety of LPS, is the major component of the outer leaflet of the outer membrane of Gram-negative bacteria making it a critical factor for bacterial adaptation. One way PA modifies its lipid A is through the addition of laurate and 2-hydroxylaurate. This secondary or late acylation is carried out by the acyltransferase, HtrB (LpxL). Analysis of the PA genome revealed the presence of two htrB homologs, PA0011 (htrB1) and PA3242 (htrB2). In this study, we were able to show that each gene identified is responsible for site-specific modification of lipid A. Additionally, deletions of either gene altered resistance to specific classes of antibiotics, cationic antimicrobial peptides and increased membrane permeability suggesting a role for these enzymes in maintaining optimal membrane organization and integrity. [ABSTRACT FROM AUTHOR]

Beyond intracellular killing, a novel neutrophil-based antimicrobial mechanism has been recently discovered: entrapment and killing by neutrophil extracellular traps (NETs). NETs consist of extruded nuclear DNA webs decorated with granule proteins. Although NET formation is an important innate immune mechanism, uncontrolled NET release damages host tissues and has been linked to several diseases including cystic fibrosis (CF). The major CF airway pathogen Pseudomonas aeruginosa establishes chronic infection. Pseudomonas imbedded within biofilms is protected against the immune system, but maintains chronic inflammation that worsens disease symptoms. Aberrant NET release from recruited neutrophils was found in CF, but the underlying mechanisms remain unclear. One of the most important Pseudomonas virulence factors is pyocyanin, a redox-active pigment that has been associated with diminished lung function in CF. Here we show that pyocyanin promotes NET formation in a time- and dose-dependent manner. Most CF Pseudomonas clinical isolates tested produce pyocyanin in vitro. Pyocyanin-derived reactive oxygen species are required for its NET release. Inhibitor experiments demonstrated involvement of Jun N-terminal Kinase (JNK) and phosphatidylinositol 3-Kinase (PI3K) in pyocyanin-induced NET formation. Pyocyanin-induced NETs also require the NADPH oxidase because NET release in chronic granulomatous disease neutrophils was greatly reduced. Comparison of neutrophils from gp91phox- and p47phox-deficient patients revealed that pyocyanin-triggered NET formation is proportional to their residual superoxide production. Our studies identify pyocyanin as the first secreted bacterial toxin that enhances NET formation. The involvement of NADPH oxidase in pyocyanin-induced NET formation represents a novel mechanism of pyocyanin toxicity. [ABSTRACT FROM AUTHOR]

Objectives: Antibiotic susceptibility methods that are commonly used to test bacterial isolates from patients with cystic fibrosis are of uncertain reliability for the polymyxins. To assess the reliability of four standard testing methods, this pilot study used a challenge set that included polymyxin-resistant isolates of Pseudomonas aeruginosa and Stenotrophomonas maltophilia. [ABSTRACT FROM PUBLISHER]

Lipid A is the pro-inflammatory component of bacterial lipopolysaccharide, the major surface component of Gram-negative bacteria. Gram-negative bacteria alter the structure of lipid A in response to specific environmental conditions including those found upon colonization of a host. The opportunistic pathogen Pseudomonas aeruginosa synthesizes a unique hexa-acylated lipid A containing palmitate and aminoarabinose during adaptation to the cystic fibrosis airway. Different lipid A species are observed in P. aeruginosa isolated from non-cystic fibrosis associated infections. Here we report that P. aeruginosa isolates from the airway of a cystic fibrosis patient with severe pulmonary disease synthesized a novel hepta-acylated lipid A. Cystic fibrosis-specific P. aeruginosa lipid A modifications result in resistance to host antimicrobial peptides and increased recognition by human Toll-like receptor 4 (TLR4). Using P. aeruginosa lipid A with different levels of acylation, we identified a 222 amino acid region in the extracellular portion of human TLR4 that is required for the differential recognition of cystic fibrosis-specific lipid A. P. aeruginosa adaptation to the human airway may, therefore, play a fundamental role in the progressive lung damage associated with cystic fibrosis. [ABSTRACT FROM AUTHOR]

The original version of this article unfortunately contained a mistake. [ABSTRACT FROM AUTHOR]