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Chronic azithromycin improves outcomes in cystic fibrosis (CF), but its mechanism of action is unclear. The OPTIMIZE trial demonstrated improvement in time to first pulmonary exacerbation in children with new Pseudomonas treated with azithromycin. Azithromycin effect on systemic markers of inflammation over 18 months was assessed by change from baseline for high-sensitivity C-reactive protein, myeloperoxidase, calprotectin and absolute neutrophil count in the OPTIMIZE population. Subjects treated with chronic azithromycin or placebo had samples collected at baseline, 39 and 78 weeks of treatment. In 129 subjects, a significant decrease in high-sensitivity C-reactive protein was present at 39 weeks in the azithromycin group compared to placebo, but no significant difference between the groups at 78 weeks. No differences in change from baseline in myeloperoxidase, calprotectin or absolute neutrophil count were present at either time point. This supports the concept of a transient immunomodulatory effect for chronic azithromycin therapy in children with CF.

In 2017, Nkam et al. published a prognostic score to predict death or lung transplant within 3 years among adult cystic fibrosis (CF) patients. Their model was developed using French CF registry data and was subsequently validated in the Canadian CF registry. We evaluated this prognostic score using data from adult patients with CF in the United States (US) CF Foundation Patient registry, combined with lung transplant records from the United Network for Organ Sharing (UNOS) Registry (2013 to 2016) (n=11,542). We found that the prognostic score had a very good discriminative index predicting death or lung transplant in the US CF population (AUC 0.88, 95% CI 0.88-0.89) with an odds ratio (OR) of 2.83 (95% CI 2.69 – 2.97) for each unit increase in the score. However, it did not provide significant additional utility over an FEV1 ≤30% of predicted as a predictor of death or lung transplant.

BACKGROUND: Given future challenges in conducting large randomized, placebo controlled trials for future CF therapeutics development, we evaluated the potential for using external historical controls to either enrich or replace traditional concurrent placebo groups in CF trials METHODS: The study included data from sequentially completed, randomized, controlled clinical trials, EPIC and OPTIMIZE respectively, evaluating optimal antibiotic therapy to reduce the risk of pulmonary exacerbation in children with early Pseudomonas aeruginosa infection. The primary treatment effect in OPTIMIZE, the risk of pulmonary exacerbation associated with azithromycin, was re-estimated in alternative designs incorporating varying numbers of participants from the earlier trial (EPIC) as historical controls. Bias and precision of these estimates were characterized. Propensity scores were derived to adjust for baseline differences across study populations, and both Poisson and Cox regression used to estimate treatment efficacy. RESULTS: Replacing 86 OPTIMIZE placebo participants with 304 controls from EPIC to mimic a fully historically controlled trial resulted an 8% reduction in risk of pulmonary exacerbations (Hazard ratio (HR):0.92 95% CI 0.61, 1.34) when not adjusting for key baseline differences between study populations. After adjustment, a 37% decrease in risk of exacerbation (HR:0.63, 95% CI 0.50,0.80) was estimated, comparable to the estimate from the original trial comparing the 86 placebo participants to 77 azithromycin participants on azithromycin (45%, HR:0.55, 95% CI: 0.34,0.86). Other adjusted approaches provided similar estimates for the efficacy of azithromycin in reducing exacerbation risk: pooling all controls from both studies provided a HR of 0.60 (95%CI 0.46, 0.77) and augmenting half the OPTIMIZE placebo participants with EPIC controls gave a HR 0.63 (95% CI 0.48, 0.82). CONCLUSIONS: The potential exists for future CF trials to utilize historical control data. Careful consideration of both the comparability of controls and of optimal methods can reduce the potential for biased estimation of treatment effects.

RationaleInhaled tobramycin and oral azithromycin are common chronic therapies in people with cystic fibrosis and Pseudomonas aeruginosa airway infection. Some studies have shown that azithromycin can reduce the ability of tobramycin to kill P. aeruginosa. This trial was done to test the effects of combining azithromycin with inhaled tobramycin on clinical and microbiological outcomes in people already using inhaled tobramycin. We theorised that those randomised to placebo (no azithromycin) would have greater improvement in forced expiratory volume in one second (FEV1) and greater reduction in P. aeruginosa sputum in response to tobramycin.MethodsA 6-week prospective, randomised, placebo-controlled, double-blind trial testing oral azithromycin versus placebo combined with clinically prescribed inhaled tobramycin in individuals with cystic fibrosis and P. aeruginosa airway infection.ResultsOver a 6-week period, including 4 weeks of inhaled tobramycin, the relative change in FEV1 did not statistically significantly differ between groups (azithromycin (n=56) minus placebo (n=52) difference: 3.44%; 95% CI: −0.48 to 7.35; p=0.085). Differences in secondary clinical outcomes, including patient-reported symptom scores, weight and need for additional antibiotics, did not significantly differ. Among the 29 azithromycin and 35 placebo participants providing paired sputum samples, the 6-week change in P. aeruginosa density differed in favour of the placebo group (difference: 0.75 log10 CFU/mL; 95% CI: 0.03 to 1.47; p=0.043).ConclusionsDespite having greater reduction in P. aeruginosa density in participants able to provide sputum samples, participants randomised to placebo with inhaled tobramycin did not experience significantly greater improvements in lung function or other clinical outcomes compared with those randomised to azithromycin with tobramycin.

Highlights • Pulmonary exacerbation difference is an important clinical trial efficacy endpoint. • Regulators have stressed use of Fuchs criteria-based exacerbation definitions. • We compared criteria-based definitions to investigator assessments of 751 events. • Criteria-based definitions were insensitive, nonspecific, and prone to bias. • An alternative exacerbation definition is needed for future CF drug development., Background Cystic fibrosis (CF) pulmonary exacerbations can be serious respiratory events and reduction in exacerbation rate or risk are important efficacy endpoints for CF therapeutic trials. Variability in exacerbation diagnoses and treatment have led drug developers to employ “objective” exacerbation definitions combining antimicrobial treatment (AT) and the presence of ≥4 of 12 respiratory criteria (first published by Fuchs et al. [NEJM 1994;331(10):637–42]). Assumptions underlying this approach have yet to be formally evaluated. Methods Respiratory events (RE) observed during a 48-week trial of ataluren (NCT02139306), a read-through agent for premature nonsense codons, were compared across six exacerbation definitions: any AT, intravenous AT (IVAT), ≥4 Fuchs criteria present, AT plus ≥4 Fuchs criteria, IVAT plus ≥4 Fuchs criteria, and investigator assessment. Fuchs definitions were evaluated by assessing missingness of individual criteria and associations between criteria presence and clinician exacerbation assessment. Results Among 751 RE, more than one third had ≥4 Fuchs criteria present but were not assessed as exacerbations by investigators. Data for ≥1 and for 4 Fuchs criteria, respectively, were missing for ~ 90% and >30% of RE. Only 6/12 Fuchs criteria were present more often when investigators assessed RE as exacerbations than when they did not. Conclusions “Objective” definitions have shortcomings inconsistent with their purpose of optimizing exacerbation capture in clinical trials : 1) they capture events clinicians do not consider exacerbations, 2) are prone to data missingness which can bias the likelihood of meeting the definition, and 3) employ criteria that are not associated with investigator assessment of exacerbation.

Rationale The prevalence of adults living with cystic fibrosis (CF) who have early-stage lung disease is increasing. Objectives Describe the prevalence and evaluate spirometric risk factors associated with the subgroup of patients with early-stage lung disease and FEV1 decline of ≥5% predicted/year. Methods Retrospective cohort study of patients ≥18 years with FEV1% predicted ≥80% included in the US CF Foundation Patient Registry from 2010–2013. Regression models were developed to estimate FEV1 rate of decline. Multivariable logistic analysis was used to assess if spirometric risk factors were associated with FEV1 decline. Measurements and main results 3,029 subjects were in the study cohort. Approximately 15% of the cohort had a substantial decline in lung function ≥5% predicted/year. In multivariable models adjusted for confounders, FEV1/FVC ratio Conclusions Even among adults with early-stage lung disease, approximately 15% are shown to progress and experience a large decline in lung function. This reinforces the concept that lung function in early-stage CF is not normal or mild. Rather, lung function decline may be delayed, but not avoided, in these individuals. Variability in FEV1% predicted and airway obstruction as measured by FEV1/FVC ratio may identify individuals at increased risk of decline. Adults with early-stage lung disease should be followed in clinic to monitor for onset of decline.

IntroductionTherapeutic advances have markedly increased life expectancy for those with cystic fibrosis (CF), resulting in a median predicted survival over 50 years. Consequently, people with CF (pwCF) are living through their reproductive years and the rate of pregnancy is rapidly rising. Despite the increased relevance of this topic, multicentre studies investigating the association between maternal health and choices made during pregnancy on maternal and fetal outcomes do not exist. Furthermore, there are very limited data on the outcomes following CF transmembrane conductance regulator (CFTR) modulator use during pregnancy and lactation.Methods and analysisMaternal andFetal Outcomes in theEra of Modulators(MAYFLOWERS) is a prospective, multicentre observational clinical trial which will enrol approximately 285 pregnant pwCF including those who are modulator ineligible and those who choose to continue or discontinue CFTR modulator therapy during pregnancy and lactation. The primary aim of this 35-month study is to assess whether lung function changes during pregnancy differ based on the continued use of modulators or other factors such as pre-existing comorbid conditions. Secondary objectives include evaluation of pregnancy related and obstetrical complications and changes in mental health.Ethics and disseminationThe design of this study required special consideration of study burden on pregnant and lactating people with chronic illness in the setting of a substantial number of unanswered questions under these conditions. MAYFLOWERS is the first prospective clinical trial examining pregnancy in CF; the outcomes will guide providers on pregnancy management in pwCF and others with chronic respiratory disease.

Chronic Azithromycin (AZM) is a common treatment for lung infection. Among adults at risk of cardiac events, AZM use has been associated with cardiovascular harm. We assessed cardiovascular safety of AZM among children with CF, as a secondary analysis of a placebo-controlled, clinical trial, in which study drug was taken thrice-weekly for a planned 18 months. Safety assessments using electrocardiogram (ECG) occurred at study enrollment, and then after 3 weeks and 18 months of participation. Among 221 study participants with a median of 18 months follow-up, increased corrected QT interval (QTc) of ≥30 msec was rare, at 3.4 occurrences per 100 person-years; and incidence of QTc prolongation was no higher in the AZM arm than the placebo arm (1.8 versus 5.4 per 100 person-years). No persons experienced QTc intervals above 500 msec. Long-term chronic AZM use was not associated with increased QT prolongation.

Improved methods are needed to risk-stratify patients with cystic fibrosis (CF) and reduced FEVWhat are the predictors of death or lung transplantation (LTx) within 2 years among patients with CF whose FEVPatients with CF, age ≥ 6 years with FEVFEVAmong individuals with CF and FEV

Inhaled tobramycin and oral azithromycin are common chronic therapies in people with cystic fibrosis andA 6-week prospective, randomised, placebo-controlled, double-blind trial testing oral azithromycin versus placebo combined with clinically prescribed inhaled tobramycin in individuals with cystic fibrosis andOver a 6-week period, including 4 weeks of inhaled tobramycin, the relative change in FEVDespite having greater reduction in

Highlights • The Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV-2) global pandemic has significantly impacted CF clinical research. • An electronic survey was sent to Therapeutic Development Network (TDN) sites to monitor the impact. • SARS-CoV-2 had an early impact on participant enrollment, research team stability, and procedures such as spirometry and sputum induction. • Trends steadily improved over the months as research activities began to recover across the TDN. • SARS-CoV-2 highlights new opportunities to expand CF research focusing on data collection outside of research centers and increased access for remote participation., The Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV-2) global pandemic significantly impacted CF clinical research within the Cystic Fibrosis Foundation Therapeutics Development Network (CFF TDN). A Research Electronic Data Capture (REDCap) survey was developed and sent to network sites to monitor and understand the impact on research teams, ongoing and anticipated clinical research, and specific clinical and research procedures. Key findings indicated an early impact on participant enrollment, research team stability, and procedures such as spirometry and sputum induction. These trends steadily improved over the months as research activities began to recover across the TDN. While SARS-CoV-2 created a significant challenge it also highlights new opportunities to expand CF research with greater focus on data collection outside of research centers and increased access for remote participation.

Rationale: New isolation of Pseudomonas aeruginosa (Pa) is generally treated with inhaled antipseudomonal antibiotics such as tobramycin inhalation solution (TIS). A therapeutic approach that complements traditional antimicrobial therapy by reducing the risk of pulmonary exacerbation and inflammation may ultimately prolong the time to Pa recurrence. Objectives: To test the hypothesis that the addition of azithromycin to TIS in children with cystic fibrosis and early Pa decreases the risk of pulmonary exacerbation and prolongs the time to Pa recurrence. Methods: The OPTIMIZE (Optimizing Treatment for Early Pseudomonas aeruginosa Infection in Cystic Fibrosis) trial was a multicenter, double-blind, randomized, placebo-controlled, 18-month trial in children with CF, 6 months to 18 years of age, with early Pa. Azithromycin or placebo was given 3× weekly with standardized TIS. Measurements and Main Results: The primary endpoint was the time to pulmonary exacerbation requiring antibiotics and the secondary endpoint was the time to Pa recurrence, in addition to other clinical and safety outcomes. A total of 221 participants (111 placebo, 110 azithromycin) out of a planned 274 were enrolled. Enrollment was stopped early by the NHLBI because the trial had reached the prespecified interim boundary for efficacy. The risk of pulmonary exacerbation was reduced by 44% in the azithromycin group as compared with the placebo group (hazard ratio, 0.56; 95% confidence interval, 0.37–0.83; P = 0.004). Weight increased by 1.27 kg in the azithromycin group compared with the placebo group (95% confidence interval, 0.01–2.52; P = 0.046). No significant differences were seen in microbiological or other clinical or safety endpoints. Conclusions: Azithromycin was associated with a significant reduction in the risk of pulmonary exacerbation and a sustained improvement in weight, but had no impact on microbiological outcomes in children with early Pa. Clinical trial registered with clinicaltrials.gov (NCT02054156).

Background Chronic Pseudomonas aeruginosa ( Pa ) airways infection, exuberant local inflammation, and progressive lung function loss are hallmarks of cystic fibrosis (CF). KB001-A is an anti-PcrV PEGylated monoclonal antibody fragment to the Type III secretion system of Pa . This 16-week study evaluated KB001-A associated effect on time-to-need for antibiotics for worsening respiratory signs and symptoms, as well as safety, and treatment-associated changes in symptom scores, inflammatory markers, and spirometry. Methods This was a randomized, double-blind, placebo-controlled, repeat-dose study in CF subjects with Pa. Intravenous 10mg/kg KB001-A or placebo infusions were administered at baseline and weeks 2, 4, 8, and 16, with a 4-week follow-up. Sputum inflammatory markers were assessed in a sub-study. Time-to-need for antibiotics was compared between groups by Kaplan Meier analysis and Cox proportional hazards modeling adjusting for randomization strata. Results Of 182 subjects, 169 received at least one infusion of KB001-A ( n =83) or placebo ( n =86). KB001-A was generally safe and well-tolerated as compared to placebo, with no significant emergent adverse effects other than one serious adverse event of elevated hepatic enzymes of unclear etiology. Time to need for antibiotics did not differ between groups (HR: 1.00; 95% CI: 0.69, 1.45, p =0.995). A 3.2 increase in ppFEV 1 from placebo favoring KB001-A was observed at week 16 (95% CI: 1.12, 5.30, p =0.003). Mean changes from baseline in log 10 sputum neutrophil elastase (NE) had a non-significant decrease (−0.27, 95% CI: −0.58,0.04, p =0.084) while IL-8 concentrations at week 16 were significantly lower (−0.27, 95% CI: −0.55,0.00, p =0.048) among KB001-A subjects ( n =16) relative to placebo ( n =13). Conclusions KB001-A was safe and well-tolerated and associated with a modest FEV 1 benefit and reduction in select sputum inflammatory markers (IL-8). KB001-A was not associated with an increased time to need for antibiotics. The lack of efficacy seen with KB001-A may be due, in part, to the low levels of the type III secretion proteins previously reported in sputum of CF patients chronically infected with Pa.

BACKGROUND: Patients with cystic fibrosis (CF) experience variable lung disease phenotypes. The R117H mutation is often associated with preserved lung function. Our objective was to compare the rate of lung function decline in patients with the R117H mutation and patients homozygous for the F508del mutation. METHODS: Rate of decline in percentage-of-predicted FEV(1) (ppFEV(1)) was analyzed using the 2006-2010 US CF Foundation Patient Registry. RESULTS: 4-year rate of decline was slower in 156 R117H patients compared with 6251 F508del patients (−0.61 vs −2.03 ppFEV(1)/year, P

BACKGROUND: Chronic Pseudomonas aeruginosa lung infection is associated with significant morbidity and mortality in cystic fibrosis (CF). It is not known whether recent advances in care have affected the rates of chronic infection. We aimed to determine if the rates of developing new chronic P. aeruginosa infection among adolescents and adults with CF significantly changed over time. METHODS: The cohort consisted of individuals with CF followed in the Cystic Fibrosis Foundation Patient Registry aged ≥13 years without chronic P. aeruginosa at baseline. Multivariable regression models accounting for within-patient correlation were used to assess the change in rate of developing chronic P. aeruginosa infection between 2003 and 2012. RESULTS: A total of 15504 individuals were followed for a median of 5 (interquartile range, 2–9) years. The annual rates of developing new chronic P. aeruginosa decreased from 14.3% in 2003 to 6.4% in 2012. After adjusting for potential confounders, relative risk (RR) of developing chronic P. aeruginosa infection decreased significantly over time compared to 2003 (P value test of trend < .001). Compared with 2003, the RR of developing chronic P. aeruginosa infection in 2012 was 0.33 (95% confidence interval, 0.30–0.37). No significant increases in risk of chronic infections with other major CF bacterial pathogens relative to 2003 were identified. CONCLUSIONS: Among individuals with CF, a significant decrease in the risk and rates of developing chronic P. aeruginosa infection between 2003 and 2012 was observed. Whether this decline results in changes in clinical outcomes warrants further exploration.

Background Lung transplantation (LTx) is frequently considered for patients with cystic fibrosis (CF) when the FEV 1 reaches 1 Methods We conducted a retrospective cohort study using the CF Foundation Patient Registry from January 1, 2003 to December 31, 2013. Adult patients (≥ 18 years) with FEV 1 Results There were 3,340 patients with an FEV 1 1 Conclusions Median survival was > 6.5 years for patients with CF and an FEV 1 1

Cystic fibrosis (CF) remains the most common life-shortening hereditary disease in white populations, with high morbidity and mortality related to chronic airway mucus obstruction, inflammation, infection, and progressive lung damage. In 1989, the discovery that CF is caused by mutations in the CFTR (cystic fibrosis transmembrane conductance regulator) gene that encodes a cAMP-dependent anion channel vital for proper Cl(−) and HCO(3)(−) transport across epithelial surfaces provided a solid foundation for unraveling underlying disease mechanisms and the development of therapeutics targeting the basic defect in people with CF. In this review, we focus on recent advances in our understanding of the molecular defects caused by different classes of CFTR mutations, implications for pharmacological rescue of mutant CFTR, and insights into how CFTR dysfunction impairs key host defense mechanisms, such as mucociliary clearance and bacterial killing in CF airways. Furthermore, we review the path that led to the recent breakthrough in the development of highly effective CFTR-directed therapeutics, now applicable for up to 90% of people with CF who carry responsive CFTR mutations, including those with just a single copy of the most common F508del mutation. Finally, we discuss the remaining challenges and strategies to develop highly effective targeted therapies for all patients and the unprecedented potential of these novel therapies to transform CF from a fatal to a treatable chronic condition.

Background We recognize an unprecedented opportunity to study the effects of withdrawing one or more chronic treatments in people with CF (PwCF) who benefit greatly from CFTR modulator therapy, but feasibility and acceptance of such a study within the community is unknown. Methods We surveyed PwCF, their families, and their acquaintances between November 16, 2018, and December 2, 2018, and CF clinicians between December 19, 2018, and January 2, 2019, about treatment withdrawal research. We sought feedback from these groups about their level of interest in this research, the consistency with which they were taking modulator and non-modulator treatments, the ways in which they conceptualized health changes, and what chronic non-modulator treatments they were most interested in stopping. We also asked for stakeholder perspectives on the design of a treatment withdrawal trial, but we intend to report these perspectives elsewhere. Results Eighty percent (541/675) of CF community respondents and 95% (206/218) of CF clinicians said that a trial of treatment simplification should be performed in the context of highly effective modulator therapy. Most current CFTR modulator users (292/359, 81%) have not stopped another chronic treatment. Worsening lung function by spirometry or increased daily symptoms were important health indicators. PwCF, their families, and/or their acquaintances ranked airway clearance techniques and inhaled antibiotics as the most burdensome treatments. Conclusions There is considerable support among the CF community and CF clinicians in the U.S. for controlled trials to assess the safety and impact of treatment simplification in patients taking highly effective modulator therapy.

The past six decades have seen remarkable improvements in health outcomes for people with cystic fibrosis (CF), which was once a fatal disease of infants and young children. However, although life expectancy for people with CF has increased substantially, the disease continues to limit survival and quality of life, and results in a significant burden of care for people with CF and their families. Moreover, recent epidemiological studies in the past two decades have shown that CF occurs and is more frequent than was previously thought in non-European populations and in regions of the world where it had not previously been described. The Lancet Respiratory Medicine Commission was formed to assess the global health and economic costs of CF care over the next three decades and to identify opportunities for progress in the care of people with CF. challenges that need to be addressed, and to serve as a blueprint for the future of CF care. This Commission was established at a time of immense change in CF clinical care including enhanced survival, widespread genetic testing supporting the diagnosis of CF in regions of the world where it was previously thought to be or non-existent and the advent of a growing number of CFTR-directed therapies which are likely to further alter the natural trajectory of the disease. This document is intended to bring to the attention of patients, health-care professionals, researchers, funders, service providers, policy makers the variety of challenges associated with this changing landscape and to serve as a blueprint for the future of CF care. what was previously a universally fatal disease of children. In considering the future of CF care, the Commission focused on five key areas, which are discussed in this report: the changing epidemiology of CF (section 1); future challenges of clinical care and its delivery (section 2); the building of CF care globally (section 3); novel therapeutics (section 4); and patient engagement (section 5) (summarized in panel 1). Since the discovery of the cystic fibrosis transmembrane regulator (CFTR) gene in the late 1980’s, triggered a surge of basic research which has enhanced understanding of the pathophysiology and the genotype/phenotype relationships of this clinically variable disease. Until recently, available treatments could be used to control symptoms and limit the complications of CF, but advances in CFTR modulator therapies to address the basic defect of CF have been phenomenal and the field is evolving rapidly. Advances in clinical care have been multifaceted and include earlier diagnosis through the implementation of newborn screening programmes, formalised airway clearance therapy, and reduced malnutrition through the use of effective pancreatic enzyme replacement and a high-energy, high protein diet. Centre-based care has become the norm in high-income countries, allowing patients to benefit from the skills of expert members of multi-disciplinary teams. Pharmacological interventions to address pulmonary manifestations now include agents that target airway mucus and airway surface liquid hydration, as well as antimicrobial therapy, including antibiotic eradication treatment in early infection and protocols for maintenance therapy in chronic infection. The challenges faced by all stakeholders in building and developing CF care globally are substantial, but many opportunities exist for improved care and better health outcomes for patients. Here, we discuss changes in diagnostic approaches including advances in genetic testing, advances in newborn screening and how it is changing landscape of the CF population, The occurrence and impact of CF in non-European populations and on different continents is explored as is. We highlight the current and future opportunities as well are the challenges for clinical care in both countries with established CF care programs and what care might look like for low- and middle-income countries where care programs more fragmented and less well funded. to the availability of integrated multi-disciplinary care and new disease-modifying treatments. The recent advances in CFTR modulator therapies to address the basic defect of CF have been phenomenal and current knowledge and future directions are appraised. The cost of new therapies is currently high and there are concerns about the affordability of those medications currently available and those under development especially when considered from a global perspective. As median age of CF has increased, there has been an associated rapid rise in the adult population, we evaluate opportunities for the use of new technologies to support engagement between patients and healthcare providers in novel ways to positively impact on the burden of care and support patient choice and yet to optimise healthcare outcomes. Challenges and opportunities in these key areas are being discussed to provide a conceptional framework for future CF care throughout the world. PANEL 1 KEY MESSAGES OF THE LANCET COMMISSION FOR CYSTIC FIBROSIS: SECTION 1 THE CHANGING EPIDEMIOLOGY OF CYSTIC FIBROSIS: 1. Newborn screening testing has been implemented in many parts of the world supporting an early diagnosis of CF. 2. Improved molecular genetic diagnostics have allowed the identification of CF in non-European populations and in individuals with nonclassical presentations of CF and related disorders. 3. CFTR related disease represents a spectrum ranging from single organ manifestations to a multi-system disease. Defining the threshold of CFTR function associated with disease manifestations is a priority to guide monitoring and treatment decisions. SECTION 2 CLINICAL CARE AND ITS DELIVERY: 1. Children with CF are healthier and the vast majority are living well into adulthood. 2. Diagnostics to allow earlier diagnosis of disease manifestations, deterioration of organ function and new airway infections are key priorities. 3. Models of care need to consider management approaches (including disease monitoring) to maintain health and delay lung transplantation and yet limit the burden of care. SECTION 3 CYSTIC FIBROSIS CARE IN DEVELOPING NATIONS: 1. Information about genetic and clinical features CF in non-European populations have improved understanding of the disease in low- and middle-income countries. 2. Access to CF therapies which is sustained and affordable for people with CF living in LMIC is needed which requires partnerships between lay organisations, governments and the pharmaceutical industry. 3. Clinical registries in countries where CF is now recognised are developing and there is a need to harmonise data elements including established CF registries to support understanding of health care outcomes especially in LMIC. SECTION 4 NOVEL THERAPEUTICS: 1. CFTR modulator therapy targeting the basic molecular defect have been developed for specific CFTR mutations and is associated with improved health outcomes including better pulmonary function and nutritional status and enhanced quality of life. 2. New CFTR modulator drugs are showing promise in CFTR mutation where earlier modulators were ineffective. Early commencement of CFTR-directed therapies may prevent the establishment of irreversible airways complications and slow progression disease in older patients. 3. Drug development requires substantial investment and contributes to the current high-cost of approved CFTR modulators. This has in turn contributed to delays in funding for such therapies in many countries and current drug prices make them unaffordable for many LMICs. SECTION 5 PATIENT EXPERIENCE, ENGAGEMENT AND INVOLVEMENT: 1. Complexity of care has increased for people with CF in parallel with increased life expectancy leading to significant burden of care and disease monitoring. Novel technologies have the potential to support self-monitoring and shared decision making between patient and health care team. 2. Mental health complications are more common in people with CF (including parents of children with CF) than the general community, impacting on quality of life. Adherence to complex therapeutic regimens is often sub-optimal and impacts of clinical outcomes. 3. Patients are highly engaged in the approaches to delivery of clinical care and their perspective of the important research priorities. CF patient organisations provide important roles in patient advocacy to delivery of clinical care, treatment access, and support and education for patients with CF and their families.

Purpose To provide a review of the status of biomarkers in cystic fibrosis drug development, including regulatory definitions and considerations, a summary of biomarkers in current use with supportive data, current gaps, and future needs. Methods Biomarkers are considered across several areas of CF drug development, including cystic fibrosis transmembrane conductance regulator modulation, infection, and inflammation. Results Sweat chloride, nasal potential difference, and intestinal current measurements have been standardized and examined in the context of multicenter trials to quantify CFTR function. Detection and quantification of pathogenic bacteria in CF respiratory cultures (e.g.: Pseudomonas aeruginosa ) are commonly used in early phase antimicrobial clinical trials, and to monitor safety of therapeutic interventions. Sputum (e.g.: neutrophil elastase, myeloperoxidase, calprotectin) and blood biomarkers (e.g.: C reactive protein, calprotectin, serum amyloid A) have had variable success in detecting response to inflammatory treatments. Conclusions Biomarkers are used throughout the drug development process in CF, and many have been used in early phase clinical trials to provide proof of concept, detect drug bioactivity, and inform dosing for later-phase studies. Advances in the precision of current biomarkers, and the identification of new biomarkers with ‘omics-based technologies, are needed to accelerate CF drug development.

Background Lung transplantation is an intervention that improves survival for adult patients with cystic fibrosis (CF). Some patients with CF are never referred for lung transplant evaluation despite meeting physiologic criteria for referral. Methods We performed a retrospective analysis of adult patients (≥18years of age) in the Cystic Fibrosis Foundation Patient Registry (CFFPR), eligible for their first evaluation for lung transplantation during the years 2001–2008 based on FEV1 Results Within the CFFPR, 1240 patients met eligibility criteria. Eight hundred and nine (65.2%) were referred for lung transplant evaluation, and 431 (34.8%) were not referred. In a multivariable model, Medicaid insurance (OR 1.79, 95% CI 1.29–2.47), older age (per 5year increase; OR 1.25, 95% CI 1.13–1.39), lack of high school graduate education (OR 2.27, 95% CI 1.42–3.64), and Burkholderia cepacia complex sputum culture positivity (OR 2.48, 95% CI 1.50–4.12) were associated with non-referral, while number of pulmonary exacerbations (OR 0.93, 95% CI 0.87–0.99) and supplemental oxygen use (OR 0.59, 95% CI 0.43–0.81) were associated with increased referral. Conclusions Despite meeting lung function criteria for lung transplant evaluation, 35% of patients with CF had not yet been referred to a lung transplant center. Predictors of non-referral included markers of low socioeconomic status, older age and B. cepacia complex sputum culture. Further work is needed to understand the outcomes for non-referred patients in order to refine referral recommendations in this population.

Rationale Lumacaftor-ivacaftor (LUM-IVA) was approved in the US in 2015 for patients with CF aged >12 homozygous for the delF508 mutation, and patients aged 6 to 12 in 2016. Objectives To examine the rate of initial LUM-IVA prescriptions following approval. Methods We compared patients eligible for LUM-IVA in the CF Foundation Patient Registry with and without prescriptions in 2015–2016. Results 5534 (53%) eligible patients had reported prescriptions. Prescription rate in children ages 6–11 was 19% and 61% among patients ≥12 years old. Individuals ≥12 with prescriptions more likely observed among those with private insurance, clinical trial participation, ages 18–30, FEV1 Conclusions LUM-IVA uptake was less rapid than what was previously observed for ivacaftor, a CFTR modulator approved for a different population. Age, insurance status, disease severity and use of other therapies differed in those prescribed LUM-IVA in the initial post-approval period.

Cystic fibrosis (CF) is a life-shortening genetic disease affecting approximately 70 000 individuals worldwide. Until recently, drug development efforts have emphasised therapies treating downstream signs and symptoms resulting from the underlying CF biological defect: reduced function of the CF transmembrane conductance regulator (CFTR) protein. The current CF drug development landscape has expanded to include therapies that enhance CFTR function by either restoring wild-type CFTR protein expression or increasing (modulating) the function of mutant CFTR proteins in cells. To date, two systemic small-molecule CFTR modulators have been evaluated in pivotal clinical trials in individuals with CF and specific mutant CFTR genotypes that have led to regulatory review and/or approval. Advances in the discovery of CFTR modulators as a promising new class of therapies have been impressive, yet work remains to develop highly effective, disease-modifying modulators for individuals of all CF genotypes. The objectives of this review are to outline the challenges and opportunities in drug development created by systemic genotype-specific CFTR modulators, highlight the advantages of sweat chloride as an established biomarker of CFTR activity to streamline early-phase development and summarise options for later phase clinical trial designs that respond to the adoption of approved genotype-specific modulators into standard of care. An optimal development framework will be needed to move the most promising therapies efficiently through the drug development pipeline and ultimately deliver efficacious and safe therapies to all individuals with CF.

Background. Pseudomonas aeruginosa (Pa) is the most important pathogen infecting the airways in individuals with cystic fibrosis. A key question is whether children with newly acquired Pa infection who are able to achieve sustained eradication after early antipseudomonal therapy demonstrate improved long-term health outcomes compared with those who are unable to achieve a sustained microbiologic response. Methods. This cohort study utilized observational follow-up data on children participating in the Early Pseudomonas Infection Control trial who received standardized therapy for newly acquired Pa. Sustained eradicators were defined as those who maintained Pa-negative cultures for 12 months after initial antipseudomonal therapy. Associations between eradication status and outcomes were assessed. Results. Of the 249 trial participants included in the study, 172 (69%) achieved sustained eradication of Pa during the trial (sustained eradicators). Over the median 5-year follow-up, sustained eradicators had a 74% reduced risk of developing chronic Pa (hazard ratio [HR], 0.26; 95% confidence interval [CI], .17–.40) and a 57% reduced risk of mucoidy (HR, 0.43; 95% CI, .25–.73) compared with nonsustained eradicators. Sustained eradicators had significantly less anti-Pa antibiotic usage during follow-up compared with nonsustained eradicators. There was no association between eradication status and clinical outcomes including rate of exacerbation and lung function decline. Conclusions. This is the first study to quantify the long-term durability of microbiological response associated with early antipseudomonal therapy, demonstrating the critical importance of optimizing antipseudomonal therapies during early Pa infection. The clinical impact of failure to achieve sustained Pa eradication remains unclear, however, and may be confounded by anti-Pa antibiotic usage. Clinical Trials Registration. NCT00097773.

Objective Patients with cystic fibrosis (CF) and mutations associated with residual CFTR chloride transport have improved survival rates compared with those homozygous for the F508del-CFTR mutation. Since little is known about rate of lung function decline in patients with CF and residual function (RF) mutations, we evaluated differences in rates of percent predicted FEV1 (ppFEV1) decline between patients with an RF mutation who were heterozygous for F508del and those who were homozygous for F508del, and whether rates of ppFEV1 decline differed across age groups. Methods Patients in the US CF Foundation Patient Registry from 2006 to 2014 with an RF mutation heterozygous for F508del were compared with F508del-homozygous patients. Mutations were identified based on clinical or in vitro evidence of residual ion transport. Annual rates of ppFEV1 decline were estimated for patients 6 to 45 years of age with ≥3 ppFEV1 values spanning ≥0.5 years in a randomly chosen 2 year period that began at the first ppFEV1 measurement in the calendar year. Results A total of 1242 RF and 11,916 F508del-homozygous patients were included. At the first visit, the RF cohort was older (mean [SD], 23.0 [12.1] vs 18.0 [9.6] years) and had better nutritional status (mean [SD] BMI z score, 0.36 [1.09] vs −0.29 [1.08]). Mean (SD) ppFEV1 differed at the first visit between cohorts (80.4 [24.8] vs 73.4 [26.5]; p Conclusion Patients with CF and an RF mutation have lower rates of lung function decline compared with F508del-homozygous patients. However, patients with an RF mutation still demonstrate progressive lung disease, particularly during young adulthood. Please refer to page A259 for declarations of interest in relation to abstract P255.

Individuals with cystic fibrosis (CF) experience frequent acute pulmonary exacerbations, which lead to decreased lung function and reduced quality of life.The goal of this study was to determine if an intervention directed toward early detection of pulmonary exacerbations using home spirometry and symptom monitoring would result in slower decline in lung function than in control subjects.We conducted a multicenter, randomized trial at 14 CF centers with subjects at least 14 years old. The early intervention arm subjects measured home spirometry and symptoms electronically twice per week. Sites were notified if a participant met criteria for an exacerbation and contacted participants to determine if treatment for acute exacerbation was required. Participants in the usual care arm were seen every 3 months and were asked to contact the site if they were concerned about worsening pulmonary symptoms.The primary outcome was the 52-week change in FEVAn intervention of home monitoring among patients with CF was able to detect more exacerbations than usual care, but this did not result in slower decline in lung function. Clinical trial registered with www.clinicaltrials.gov (NCT01104402).

Purpose of review Evolving cystic fibrosis 'standards of care' have influenced recent cystic fibrosis clinical trial designs for new therapies; care additions/improvements will require innovative trial designs to maximize feasibility and efficacy detection. Recent findings Three cystic fibrosis therapeutic areas (pulmonary exacerbations, Pseudomonas aeruginosa airway infections, and reduced cystic fibrosis transmembrane conductance regulator [CFTR] protein function) differ with respect to the duration for which recognized 'standards of care' have been available. However, developers of new therapies in all the three areas are affected by similar challenges: standards of care have become so strongly entrenched that traditional placebo-controlled studies in cystic fibrosis populations likely to benefit from newer therapies have become less and less feasible. Today, patients/clinicians are more likely to entertain participation in active-comparator trial designs, that have substantial challenges of their own. Foremost among these are the selection of 'valid' active comparator(s), estimation of a comparator's current clinical efficacy (required for testing noninferiority hypotheses), and effective blinding of commercially available comparators. Summary Recent and future cystic fibrosis clinical trial designs will have to creatively address this collateral result of successful past development of effective cystic fibrosis therapies: patients and clinicians are much less likely to accept simple, placebo-controlled studies to evaluate future therapies.

BackgroundCF infants often do not grow as expected which adversely affects later clinical outcomes, thus sensitive early measures of growth deficiency are important. This study compared attained growth for age with velocity standards to determine which better predicts growth deficits at 24months of age.MethodsGrowth deficiency in infancy based on weight and length velocity, and attained growth was calculated for 1992 infants in the US CF Foundation National Registry using the World Health Organization (WHO) and US growth standards. One, two and three month increments were used for calculating velocity and pooled for each age interval. Sensitivity and specificity of early indicators to predict growth deficiency at 24months were calculated.ResultsObserved prevalence of weight deficiency (

Pseudomonas aeruginosa undergoes phenotypic changes during cystic fibrosis (CF) lung infection. Although mucoidy is traditionally associated with transition to chronic infection, we hypothesized that additional in vitro phenotypes correlate with this transition and contribute to disease.To characterize the relationships between in vitro P. aeruginosa phenotypes, infection stage, and clinical outcomes.A total of 649 children with CF and newly identified P. aeruginosa were followed for a median 5.4 years during which a total of 2,594 P. aeruginosa isolates were collected. Twenty-six in vitro bacterial phenotypes were assessed among the isolates, including measures of motility, exoproduct production, colony morphology, growth, and metabolism.P. aeruginosa phenotypes present at the time of culture were associated with both stage of infection (new onset, intermittent, or chronic) and the primary clinical outcome, occurrence of a pulmonary exacerbation (PE) in the subsequent 2 years. Two in vitro P. aeruginosa phenotypes best distinguished infection stages: pyoverdine production (31% of new-onset cultures, 48% of intermittent, 69% of chronic) and reduced protease production (31%, 39%, and 65%, respectively). The best P. aeruginosa phenotypic predictors of subsequent occurrence of a PE were mucoidy (odds ratio, 1.75; 95% confidence interval, 1.19-2.57) and reduced twitching motility (odds ratio, 1.43; 95% confidence interval, 1.11-1.84).In this large epidemiologic study of CF P. aeruginosa adaptation, P. aeruginosa isolates exhibited two in vitro phenotypes that best distinguished early and later infection stages. Among the many phenotypes tested, mucoidy and reduced twitching best predicted subsequent PE. These phenotypes indicate potentially useful prognostic markers of transition to chronic infection and advancing lung disease.

Rationale: Ivacaftor is a cystic fibrosis transmembrane conductance regulator (CFTR) potentiator recently approved for patients with CF age 6 and older with the G551D mutation. Objectives: To evaluate ivacaftor in a postapproval setting and determine mechanism of action and response of clinically relevant markers. Methods: We conducted a longitudinal cohort study in 2012–2013 in G551D CF patients age 6 and older with no prior exposure to ivacaftor. Study assessments were performed at baseline, 1, 3, and 6 months after ivacaftor initiation. Substudies evaluated mucociliary clearance, β-adrenergic sweat secretion rate, gastrointestinal pH, and sputum inflammation and microbiology Measurements and Main Results: A total of 151 of 153 subjects were prescribed ivacaftor and 88% completed the study through 6 months. FEV1 % predicted improved from baseline to 6 months (mean absolute change, 6.7%; P < 0.001). Similarly, body mass index improved from baseline to 6 months (mean change, 0.8 kg/m2; P < 0.001). Sweat chloride decreased from baseline to 6 months (mean change, −53.8 mmol/L; 95% confidence interval, −57.7 to −49.9; P < 0.001), reflecting augmented CFTR function. There was significant improvement in hospitalization rate (P < 0.001) and Pseudomonas aeruginosa burden (P < 0.01). Significant improvements in mucociliary clearance (P < 0.001), gastrointestinal pH (P = 0.001), and microbiome were also observed, providing clinical mechanisms underlying the therapeutic benefit of ivacaftor. Conclusions: Significant clinical and physiologic improvements were observed on initiation of ivacaftor in a broad patient population, including reduced infection with P. aeruginosa. Biomarker studies substantially improve the understanding of the mechanistic consequences of CFTR modulation on pulmonary and gastrointestinal physiology.

Background. Pseudomonas aeruginosa is a key respiratory pathogen in people with cystic fibrosis (CF). Due to its association with lung disease progression, initial detection of P. aeruginosa in CF respiratory cultures usually results in antibiotic treatment with the goal of eradication. Pseudomonas aeruginosa exhibits many different phenotypes in vitro that could serve as useful prognostic markers, but the relative relationships between these phenotypes and failure to eradicate P. aeruginosa have not been well characterized. Methods. We measured 22 easily assayed in vitro phenotypes among the baseline P. aeruginosa isolates collected from 194 participants in the 18-month EPIC clinical trial, which assessed outcomes after antibiotic eradication therapy for newly identified P. aeruginosa. We then evaluated the associations between these baseline isolate phenotypes and subsequent outcomes during the trial, including failure to eradicate after antipseudomonal therapy, emergence of mucoidy, and occurrence of an exacerbation. Results. Baseline P. aeruginosa isolates frequently exhibited phenotypes thought to represent chronic adaptation, including mucoidy. Wrinkly colony surface and irregular colony edges were both associated with increased risk of eradication failure (hazard ratios [95% confidence intervals], 1.99 [1.03–3.83] and 2.14 [1.32–3.47], respectively). Phenotypes reflecting defective quorum sensing were significantly associated with subsequent mucoidy, but no phenotype was significantly associated with subsequent exacerbations during the trial. Conclusions. Pseudomonas aeruginosa phenotypes commonly considered to reflect chronic adaptation were observed frequently among isolates at early detection. We found that 2 easily assayed colony phenotypes were associated with failure to eradicate after antipseudomonal therapy, both of which have been previously associated with altered biofilm formation and defective quorum sensing.

Background Biomarkers reflective of disease activity in cystic fibrosis (CF) have the potential to improve patient care, particularly during CF pulmonary exacerbations (CFPEs). Although blood-based biomarkers have been studied in CFPE for nearly 3 decades, none have been integrated into routine clinical practice. To facilitate progress in this area, we performed a systematic review evaluating blood-based biomarkers during CFPE. Methods MEDLINE, EMBASE, and CENTRAL were searched to identify relevant studies published from January 1995 to August 2012. We included all full-text studies examining systemic (blood-based) biomarkers to aid in the diagnosis of CFPE, predict outcomes of CFPE, and/or monitor the response to CFPE treatment. Results Seventy-eight unique blood-based biomarkers have been studied to date, mainly inflammatory cytokines, acute phase reactants, and markers of oxidative stress. C-reactive protein (CRP) consistently correlated with disease activity, with a statistically significant increase from stable to exacerbation state in five of six studies, and changes in response to CFPE treatment, with a statistically significant decrease from the beginning to the end of CFPE treatment in 18 of 20 studies. Other promising biomarkers of CFPE disease activity include neutrophil elastase antiproteinase complex, IL-6, myeloperoxidase (MPO), lactoferrin, and calprotectin. Conclusions Although there are several blood-based biomarkers with evidence for application within the CFPE setting, CRP has been the most widely studied biomarker demonstrating the potential for clinical usefulness. Further validation studies and clinical trials are required to determine whether blood-based biomarkers can be used to ultimately improve health outcomes in the setting of a CFPE.

Chronic antibiotic suppression of cystic fibrosis (CF) infections has increased in the United States, as has isolation of Pseudomonas aeruginosa with reduced antibiotic susceptibility. However, analysis of the susceptibilities of 193 initial P aeruginosa clinical isolates suggests that antibiotic susceptibilities are comparable with wild-type strains despite expanded antipseudomonal treatment in the CF community.

In a chronic disease setting such as cystic fibrosis (CF), antibiotics are often prescribed for emergent symptoms and it is unclear whether this affects endpoints in a clinical trial. Pulmonary exacerbations (PEs) are defined episodes of acute worsening and a key clinical efficacy measure in CF. Our hypothesis was that acute antibiotics given for illnesses not meeting the PE definition may alter estimates of treatment effect that do not account for this antibiotic use.A randomized, placebo-controlled trial of azithromycin (AZ) including 260 participants with CF was utilized for this study. PEs were defined using a priori criteria. Physician initiated antibiotic therapy (PIT) not meeting the PE endpoint was characterized and its impact on treatment effect assessed.40% (104/260) of participants were prescribed 188 courses of PIT in the absence of a PE; 19% (25/129) of placebo and 10% (13/131) of AZ participants received ≥2 courses of PIT and never fulfilled the PE definition (9% difference, 95% confidence interval: 1%, 18%, p = 0.04). Accounting for PIT through use of a composite endpoint including time to PE or need for repeated PIT altered treatment effect estimates (a 56% reduction in the event rate comparing AZ to placebo [p0.0001] as compared to a 50% reduction not accounting for PIT [p = 0.003]).PIT is common in CF and may impact treatment effect estimates. Optimization of the PE endpoint to include meaningful events necessitating treatment may improve our ability to conduct efficient trials by reducing the sample size 30-50%, ultimately enabling rapid evaluation of new therapies.

In 2006, the US FDA issued a ‘Guidance for Industry’ regarding submission of New Drug Applications for pancreatic enzyme replacement therapy (PERT) products. Five oral delayed-release PERT products have been approved by the FDA, and several others are under development and/ or evaluation for New Drug Application submission. We present in this paper recommendations of the Cystic Fibrosis Foundation's Cystic Fibrosis (CF) Therapeutics Development Network and Data Safety Monitoring Board regarding study design considerations for evaluating PERT products in patients with CF. Careful attention to study design and accuracy of the outcome measures has confirmed our understanding of the efficacy and safety of PERT for the treatment of exocrine pancreatic insufficiency of CF.

Rationale The Early Pseudomonal Infection Control (EPIC) randomized trial rigorously evaluated the efficacy of different antibiotic regimens for eradication of newly identified Pseudomonas (Pa) in children with cystic fibrosis (CF). Protocol based therapy in the trial was provided based on culture positivity independent of symptoms. It is unclear whether outcomes observed in the clinical trial were different than those that would have been observed with historical standard of care driven more heavily by respiratory symptoms than culture positivity alone. We hypothesized that the incidence of Pa recurrence and hospitalizations would be significantly reduced among trial participants as compared to historical controls whose standard of care preceded the widespread adoption of tobramycin inhalation solution (TIS) as initial eradication therapy at the time of new isolation of Pa. Methods Eligibility criteria from the trial were used to derive historical controls from the Epidemiologic Study of CF (ESCF) who received standard of care treatment from 1995 to 1998, before widespread availability of TIS. Pa recurrence and hospitalization outcomes were assessed over a 15-month time period. Results As compared to 100% of the 304 trial participants, only 296/608 (49%) historical controls received antibiotics within an average of 20 weeks after new onset Pa. Pa recurrence occurred among 104/298 (35%) of the trial participants as compared to 295/549 (54%) of historical controls (19% difference, 95% CI: 12%, 26%, P

Rationale Emergence of elevated liver function tests (LFTs) during a clinical trial may be due to underlying disease factors of the participants, thus cofounding safety assessments of therapies. Limited data exist addressing the frequency of elevated LFTs in the chronic disease setting of cystic fibrosis (CF). The objectives of this study were to characterize emergence rates of elevated LFTs in CF trials and their association with clinical outcomes. Methods The cohort was comprised of participants of three completed multicenter CF trials. LFTs were collected as safety endpoints, and hospitalization rates and changes in pulmonary function and weight were used to assess the association between elevated LFTs and clinical outcome. Results 93/376 (25%) participants had ≥ 1 emergent elevated LFT exceeding the normal reference range over an average 8.3 month follow-up, and only 12/93 (13%) had a value determined by the physician as clinically significant. The emergence of an elevated LFT was not significantly associated with a greater rate of decline in pulmonary function or weight as compared to participants with normal LFTs. The emergence of an elevated LFT value was however associated with a higher hospitalization risk (relative risk:1.67, 95% confidence interval:1.11, 2.53). Conclusions Elevated LFTs are common among CF trials, although in most cases they are not deemed clinically significant. These elevated LFTs are associated with more frequent hospitalizations, but additional studies are needed to determine the causality of this association. Therapeutic trials in CF must define a priori criteria for clinical significance of elevated LFTs to enable unbiased safety assessments.

Background New CFTR modulators are in development that sponsors anticipate will be comparable or superior to approved modulators. Testing these agents for efficacy will require either placebo-controlled or active-comparator trials. Methods We surveyed US CF physicians and their patients eligible to receive approved modulators or their families for willingness to participate in placebo-controlled modulator trials of varying duration. Results Interest in placebo-controlled trials of short duration (2–4weeks) was greatest, with few respondents, particularly among patient respondents, willing to consider 6month studies. Patients/families with access to approved modulators were consistently less interested in placebo-controlled modulator trials of any duration. Conclusions Sample size and interpretability advantages of placebo-controlled trials outweigh alternative active-comparator trials, but must consider physician and patient thresholds for forgoing treatment with approved modulators. Enrollment will be most feasible for short-duration trials and those conducted among populations without access to approved modulators.

Background Forced expiratory volume in 1s (FEV 1 ) is an established marker of cystic fibrosis (CF) disease progression that is used to capture clinical course and evaluate therapeutic efficacy. The research community has established FEV 1 surveillance data through a variety of observational data sources such as patient registries, and there is a growing pipeline of new CF therapies demonstrated to be efficacious in clinical trials by establishing improvements in FEV 1 . Results In this review, we summarize from a statistical perspective the clinical relevance of FEV 1 based on its association with morbidity and mortality in CF, its role in epidemiologic studies of disease progression and comparative effectiveness, and its utility in clinical trials. In addition, we identify opportunities to advance epidemiologic research and the clinical development pipeline through further statistical considerations. Conclusions Our understanding of CF disease course, therapeutics, and clinical care has evolved immensely in the past decades, in large part due to the thoughtful application of rigorous research methods and meaningful clinical endpoints such as FEV 1 . A continued commitment to conduct research that minimizes the potential for bias, maximizes the limited patient population, and harmonizes approaches to FEV 1 analysis while maintaining clinical relevance, will facilitate further opportunities to advance CF care.

Background Little is known about risk factors for chronic and mucoid Pseudomonas aeruginosa (Pa) infection in cystic fibrosis (CF) adults, and whether the prevalence is changing. Methods We employed a retrospective cohort to analyze data from a single adult CF center (2002 to 2012). Regression models were used to assess independent predictors and change in prevalence of chronic and mucoid Pa infection over time. Results The odds ratio of mucoid Pa infection was significantly less in individuals with better baseline lung function (OR 0.84,95%CI:0.77–0.92) and those diagnosed after the age of 25 (OR 0.21, 95%CI:0.05–0.95). The prevalence of chronic Pa and mucoid Pa decreased during the time interval. After adjusting for confounders, the observed decrease in chronic and mucoid Pa between 2002 and 2012 was no longer significant. Conclusions The prevalence of chronic and mucoid Pa is decreasing. Larger studies are needed to confirm these regional trends and their significance. Electronic supplementary material The online version of this article (doi:10.1186/s12890-016-0333-y) contains supplementary material, which is available to authorized users.

Chronic Pseudomonas aeruginosa infections cause significant morbidity in patients with cystic fibrosis (CF). Over years to decades, P. aeruginosa adapts genetically as it establishes chronic lung infections. Nonsynonymous mutations in lasR, the quorum-sensing (QS) master regulator, are common in CF. In laboratory strains of P. aeruginosa, LasR activates transcription of dozens of genes, including that for another QS regulator, RhlR. Despite the frequency with which lasR coding variants have been reported to occur in P. aeruginosa CF isolates, little is known about their consequences for QS. We sequenced lasR from 2,583 P. aeruginosa CF isolates. The lasR sequences of 580 isolates (22%) coded for polypeptides that differed from the conserved LasR polypeptides of well-studied laboratory strains. This collection included 173 unique lasR coding variants, 116 of which were either missense or nonsense mutations. We studied 31 of these variants. About one-sixth of the variant LasR proteins were functional, including 3 with nonsense mutations, and in some LasR-null isolates, genes that are LasR dependent in laboratory strains were nonetheless expressed. Furthermore, about half of the LasR-null isolates retained RhlR activity. Therefore, in some CF isolates the QS hierarchy is altered such that RhlR quorum sensing is independent of LasR regulation. Our analysis challenges the view that QS-silent P. aeruginosa is selected during the course of a chronic CF lung infection. Rather, some lasR sequence variants retain functionality, and many employ an alternate QS strategy involving RhlR., IMPORTANCE Chronic Pseudomonas aeruginosa infections, such as those in patients with the genetic disease cystic fibrosis, are notable in that mutants with defects in the quorum-sensing transcription factor LasR frequently arise. In laboratory strains of P. aeruginosa, quorum sensing activates transcription of dozens of genes, many of which encode virulence factors, such as secreted proteases and hydrogen cyanide synthases. In well-studied laboratory strains, LasR-null mutants have a quorum-sensing-deficient phenotype. Therefore, the presence of LasR variants in chronic infections has been interpreted to indicate that quorum-sensing-regulated products are not important for those infections. We report that some P. aeruginosa LasR variant clinical isolates are not LasR-null mutants, and others have uncoupled a second quorum-sensing system, the RhlR system, from LasR regulation. In these uncoupled isolates, RhlR independently activates at least some quorum-sensing-dependent genes. Our findings suggest that quorum sensing plays a role in chronic P. aeruginosa infections, despite the emergence of LasR coding variants.