A randomized trial of oral prednisone for cystic fibrosis pulmonary exacerbation treatment

BACKGROUND

Elevated markers of systemic and pulmonary inflammation are associated with failure to recover lung function following pulmonary exacerbations (PExs) in people with cystic fibrosis (pwCF). Our aim was to determine whether adjuvant oral prednisone treatment would improve recovery of forced expiratory volume in 1 second (ppFEV1) in CF PExs not responding to antibiotic therapy.

METHODS

This was a randomized, double-blind, placebo-controlled trial in pwCF treated with intravenous (IV) antibiotics for a PEx. At Day 7, those who had not returned to >90% baseline ppFEV1 were randomized to adjuvant prednisone 1 mg·kg-1 twice daily (max 60 mg/day) or placebo for 7 days. The primary outcome was the difference in proportion of subjects who recovered >90% baseline ppFEV1 at Day 14 of IV antibiotic therapy.

RESULTS

173 subjects were enrolled, with 76 randomized. 50% of subjects in the prednisone group recovered baseline FEV1 on Day 14 compared to 39% of subjects in the placebo group for a difference of 11% (95% CI -11, 34%, p=0.34). The mean (sd) change in ppFEV1 from Day 7 to Day 14 was 6.8% predicted (8.8) in the prednisone group and 4.6% (6.9) in the placebo group (mean difference 2.2% predicted 95% CI -1.5, 5.9%, p=0.24). Time to subsequent exacerbation was not prolonged in prednisone treated subjects (HR 0.83, 95% CI 0.45, 1.53; p=0.54).

CONCLUSIONS

This study failed to detect a difference in ppFEV1 recovery between adjuvant oral prednisone and placebo treatment in pwCF not responding at day 7 of IV antibiotic therapy for PExs.

Update on the diagnosis and management of cystic fibrosis pulmonary exacerbations

Pulmonary exacerbations in people with cystic fibrosis are associated with significant morbidity and reduced quality of life. Pulmonary exacerbation treatment guidelines, published by an expert panel assembled by the Cystic Fibrosis Foundation nearly 15 years ago, were primarily consensus-based as there were several gaps in the evidence base. In particular, limited evidence existed regarding optimal pulmonary exacerbation treatment strategies, including duration of antibiotic therapy, treatment location, antibiotic selection, and the role of systemic corticosteroids. Over the last decade, results from observational studies and large multi-center randomized controlled trials have begun to answer important questions related to pulmonary exacerbation treatment. This review focuses on the diagnosis, etiology, and changing epidemiology of pulmonary exacerbations, and also summarizes the most recent and up-to-date studies describing pulmonary exacerbation treatment. Finally, this review provides consideration for future pulmonary exacerbation research priorities, particularly in the current highly effective modulator therapy era.

Exploring Mechanisms of Lipid Nanoparticle-Mucus Interactions in Healthy and Cystic Fibrosis Conditions

Mucus forms the first defense line of human lungs, and as such hampers the efficient delivery of therapeutics to the underlying epithelium. This holds particularly true for genetic cargo such as CRISPR-based gene editing tools which cannot readily surmount the mucosal barrier. While lipid nanoparticles (LNPs) emerge as versatile non-viral gene delivery systems that can help overcome the delivery challenge, many knowledge gaps remain, especially for diseased states such as cystic fibrosis (CF). This study provides fundamental insights into Cas9 mRNA or ribonucleoprotein-loaded LNP-mucus interactions in healthy and diseased states by assessing the impact of the genetic cargo, mucin sialylation, mucin concentration, ionic strength, pH, and polyethylene glycol (PEG) concentration and nature on LNP diffusivity leveraging experimental approaches and Brownian dynamics (BD) simulations. Taken together, this study identifies key mucus and LNP characteristics that are critical to enabling a rational LNP design for transmucosal delivery.

Cardiopulmonary Exercise Testing Provides Prognostic Information in Advanced Cystic Fibrosis Lung Disease

Rationale: Cardiopulmonary exercise testing (CPET) provides prognostic information in cystic fibrosis (CF); however, its prognostic value for patients with advanced CF lung disease is unknown. Objectives: To determine the prognostic value of CPET on the risk of death or lung transplant (LTX) within 2 years. Methods: We retrospectively collected data from 20 CF centers in Asia, Australia, Europe, and North America on patients with a forced expiratory volume in 1 second (FEV1) ⩽ 40% predicted who performed a cycle ergometer CPET between January 2008 and December 2017. Time to death/LTX was analyzed using mixed Cox proportional hazards regression. Conditional inference trees were modeled to identify subgroups with increased risk of death/LTX. Results: In total, 174 patients (FEV1, 30.9% ± 5.8% predicted) were included. Forty-four patients (25.5%) died or underwent LTX. Cox regression analysis adjusted for age, sex, and FEV1 revealed percentage predicted peak oxygen uptake ([Formula: see text]o2peak) and peak work rate (Wpeak) as significant predictors of death/LTX: adjusted hazard ratios per each additional 10% predicted were 0.60 (95% confidence interval, 0.43-0.90; P = 0.008) and 0.60 (0.48-0.82; P < 0.001). Tree-structured regression models, including a set of 11 prognostic factors for survival, identified Wpeak to be most strongly associated with 2-year risk of death/LTX. Probability of death/LTX was 45.2% for those with a Wpeak ⩽ 49.2% predicted versus 10.9% for those with a Wpeak > 49.2% predicted (P < 0.001). Conclusions: CPET provides prognostic information in advanced CF lung disease, and Wpeak appears to be a promising marker for LTX referral and candidate selection.

Lung function decline is mitigated following liver transplantation in people with cystic fibrosis: A retrospective cohort study

There is paucity of literature on the health outcomes following liver transplantation (LT) in people with cystic fibrosis (pwCF). We aim to evaluate changes in lung function following LT in pwCF. We performed a retrospective cohort study of pwCF who underwent LT between 1987 and 2019 in the United States and Canada. Simultaneous lung-liver transplants and individuals who had lung transplant prior to LT were excluded. We analyzed pre-LT and post-LT percent predicted forced expiratory volume in 1 second, body mass index, rates of pulmonary exacerbation, and post-LT overall survival. A total of 402 LT recipients were included. The median age of transplant was 14.9 years and 69.7% of the transplants were performed in children less than 18 years old. The rate of decline in percent predicted forced expiratory volume in 1 second was attenuated after LT from -2.2% to -0.7% predicted per year with a difference of 1.5% predicted per year (95% CI, 0.8, 2.2; p < 0.001). Following LT, the rate of decline in body mass index was reduced, and there were fewer pulmonary exacerbations (0.6 pre vs. 0.4 post; rate ratio 0.7, p < 0.01). The median survival time post-transplant was 13.9 years and the overall probability of survival at 5 years was 77.6%. Those with higher lung function pre-LT had a lower risk of death post-LT, and those with genotypes other than F508 deletion had worse survival. LT in pwCF occurs most often in children and adolescents and is associated with a slower rate of decline in lung function and nutritional status, and a reduction in pulmonary exacerbations.

Standards for the care of people with cystic fibrosis; establishing and maintaining health

This is the second in a series of four papers updating the European Cystic Fibrosis Society (ECFS) standards for the care of people with CF. This paper focuses on establishing and maintaining health. The guidance is produced using an evidence-based framework and with wide stakeholder engagement, including people from the CF community. Authors provided a narrative description of their topic and statements, which were more directive. These statements were reviewed by a Delphi exercise, achieving good levels of agreement from a wide group for all statements. This guidance reinforces the importance of a multi-disciplinary CF team, but also describes developing models of care including virtual consultations. The framework for health is reinforced, including the need for a physically active lifestyle and the strict avoidance of all recreational inhalations, including e-cigarettes. Progress with cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapy is reviewed, including emerging adverse events and advice for dose reduction and interruption. This paper contains guidance that is pertinent to all people with CF regardless of age and eligibility for and access to modulator therapy.

Measuring the burden of cystic fibrosis: A scoping review

BACKGROUND

Cystic fibrosis (CF) contributes a significant economic burden on individuals, healthcare systems, and society. Understanding the economic impact of CF is crucial for planning resource allocation.

METHODS

We conducted a scoping review of literature published between 1990 and 2022 that reported the cost of illness, and/or economic burden of CF. Costs were adjusted for inflation and reported as United States dollars.

RESULTS

A total of 39 studies were included. Direct healthcare costs (e.g., medications, inpatient and outpatient care) were the most frequently reported. Most studies estimated the cost of CF using a prevalence-based (n = 18, 46.2 %), bottom-up approach (n = 23, 59 %). Direct non-healthcare costs and indirect costs were seldom included. The most frequently reported direct cost components were medications (n = 34, 87.2 %), inpatient care (n = 33, 84.6 %), and outpatient care (n = 31, 79.5 %). Twenty-eight percent (n = 11) of studies reported the burden of CF from all three perspectives (healthcare system (payer), individual, and society). Indirect costs of CF were reported in approximately 20 % of studies (n = 8). The reported total cost of CF varied widely, ranging from $451 to $160,000 per person per year (2022 US$). The total cost depended on the number of domains and perspectives included in each study.

CONCLUSIONS

Most studies only reported costs to the healthcare system (i.e., hospitalizations and healthcare encounters) which likely underestimates the total costs of CF. The wide range of costs reported highlights the importance of standardizing perspectives, domains and costs when estimating the economic burden of CF.

Long-term safety and efficacy of elexacaftor/tezacaftor/ivacaftor in people with cystic fibrosis and at least one F508del allele: 144-week interim results from a 192-week open-label extension study

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 (FEV1) 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 FEV1 % 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.

Cystic fibrosis survival outcomes following second lung transplant: The north American experience

INTRODUCTION

Re-transplant is an option for those who develop end-stage lung disease due to rejection; however, little data exist following re-transplantation in cystic fibrosis (CF).

METHODS

Data from the Canadian CF Registry and US CF Foundation Patient Registry supplemented with data from United Network for Organ Sharing were used. Individuals who underwent a 2nd lung transplant between 2005 and 2019 were included. The Kaplan-Meier method was used to estimate the probability of survival post-second transplant at 1, 3, and 5-years.

RESULTS

Of those people who were waitlisted for a second transplant (N = 818), a total of 254 (31%) died waiting, 395 (48%) were transplanted and 169 (21%) people were alive on the waitlist. Median survival time after 2nd lung transplant was 3.3 years (95% CI: 2.8-4.1). The 1-, 3- and 5-year survival rates were 77.4% (95% CI: 73.1-82%), 52% (95% CI: 46.7-58%) and 39.4% (95% CI: 34.1-45.6%).

CONCLUSIONS

Survival following second lung transplant in CF patients is lower than estimates following the first transplant. Over half of subjects who are potentially eligible for a second transplant die without receiving a second organ. This warrants further investigation.

Breath of fresh insight: unraveling the evolution of our understanding of cystic fibrosis pulmonary exacerbations

PURPOSE OF REVIEW

Pulmonary exacerbations are critical events with significant negative impacts in persons with cystic fibrosis, but their diagnosis and management are highly variable. Highly effective modulator therapies have greatly improved health and reduced exacerbation events, but have also reshaped how they present. This review discusses the complexities of the diagnosis and management of pulmonary exacerbations as well as the emerging work and evidence in this area.

RECENT FINDINGS

The shifting epidemiology and our understanding of risk factors for pulmonary exacerbations are discussed. As symptoms may be more subtle in the modulator context, novel technologies including studies of remote monitoring are presented. The continued relevance of pulmonary exacerbations, the heterogeneity in their management, as well as current and forthcoming clinical trials to optimize treatment approaches are detailed.

SUMMARY

In spite of the dramatic reductions in pulmonary exacerbations, airway infections persist, a proportion of persons with cystic fibrosis either on or off modulator therapies continue to experience exacerbation events, and long-term data is lacking. Innovative approaches and studies will be crucial to enable standardized and generalizable strategies to improve outcomes in persons with cystic fibrosis.

Advancing the pipeline of cystic fibrosis clinical trials: a new roadmap with a global trial network perspective

The growing use of modulator therapies aimed at restoring cystic fibrosis transmembrane conductance regulator (CFTR) protein function in people with cystic fibrosis has fundamentally altered clinical trial strategies needed to advance new therapeutics across an orphan disease population that is now divided by CFTR modulator eligibility. The development of a robust pipeline of nucleic acid-based therapies (NABTs)-initially directed towards the estimated 10% of the cystic fibrosis population who are genetically ineligible for, or intolerant of, CFTR modulators-is dependent on the optimisation of restricted trial participant resources across multiple development programmes, a challenge that will preclude the use of gold standard placebo-controlled trials. Advancement of a full pipeline of symptomatic therapies across the entire cystic fibrosis population will be challenged by smaller effect sizes and uncertainty regarding their clinical importance in a growing modulator-treated population with more mild and stable pulmonary disease. In this Series paper, we aim to lay the foundation for clinical trial strategy and community partnership that must deviate from established and familiar precedent to advance the future pipeline of cystic fibrosis therapeutics.

Factors associated with frequent high-cost individuals with cystic fibrosis and their healthcare utilization and cost patterns

Cystic fibrosis (CF) is a progressive multi-organ disease with significant morbidity placing extensive demands on the healthcare system. Little is known about those individuals with CF who continually incur high costs over multiple years. Understanding their characteristics may help inform opportunities to improve management and care, and potentially reduce costs. The purpose of this study was to identify and understand the clinical and demographic attributes of frequent high-costing CF individuals and characterize their healthcare utilization and costs over time. A longitudinal study of retrospective data was completed in British Columbia, Canada by linking the Canadian CF Registry with provincial healthcare administrative databases for the period between 2009 and 2017. Multivariable Cox regression models were employed to identify baseline factors associated with becoming a frequent high-cost CF user (vs. not a frequent high-cost CF user) in the follow-up period. We found that severe lung impairment (Hazard Ratio [HR]: 3.71, 95% confidence interval [CI], 1.49-9.21), lung transplantation (HR: 4.23, 95% CI, 1.68-10.69), liver cirrhosis with portal hypertension (HR: 10.96, 95% CI: 3.85-31.20) and female sex (HR: 1.97, 95% CI: 1.13-3.44) were associated with becoming a frequent high-cost CF user. Fifty-nine (17% of cohort) frequent high-cost CF users accounted for more than one-third of the overall total healthcare costs, largely due to inpatient hospitalization and outpatient medication costs.

Development of the Cystic Fibrosis Questionnaire-Revised-8 Dimensions: Estimating Utilities From the Cystic Fibrosis Questionnaire-Revised

OBJECTIVES

Cystic fibrosis (CF) limits survival and negatively affects health-related quality of life (HRQOL). Cost-effectiveness analysis (CEA) may be used to make reimbursement decisions for new CF treatments; nevertheless, generic utility measures used in CEA, such as EQ-5D, are insensitive to meaningful changes in lung function and HRQOL in CF. Here we develop a new, CF disease-specific, preference-based utility measure based on the adolescent/adult version of the Cystic Fibrosis Questionnaire-Revised (CFQ-R), a widely used, CF-specific, patient-reported measure of HRQOL.

METHODS

Blinded CFQ-R data from 4 clinical trials (NCT02347657, NCT02392234, NCT01807923, and NCT01807949) were used to identify discriminating items for a classification system using psychometric (eg, factor and Rasch) analyses. Thirty-two health states were selected for a time trade-off (TTO) exercise with a representative sample of the UK general population. TTO utilities were used to estimate a preference-based scoring algorithm by regression analysis (tobit models with robust standard errors clustered on participants with censoring at -1).

RESULTS

A classification system with 8 dimensions (CFQ-R-8 dimensions; physical functioning, vitality, emotion, role functioning, breathing difficulty, cough, abdominal pain, and body image) was generated. TTO was completed by 400 participants (mean age, 47.3 years; 49.8% female). Among the regression models evaluated, the tobit heteroscedastic-ordered model was preferred, with a predicted utility range from 0.236 to 1, no logical inconsistencies, and a mean absolute error of 0.032.

CONCLUSION

The CFQ-R-8 dimensions is the first disease-specific, preference-based scoring algorithm for CF, enabling estimation of disease-specific utilities for CEA based on the well-validated and widely used CFQ-R.

Global burden of nontuberculous mycobacteria in the cystic fibrosis population: a systematic review and meta-analysis

Background

People living with cystic fibrosis have an increased risk of lung infection with nontuberculous mycobacteria (NTM), the prevalence of which is reportedly increasing. We conducted a systematic review of the literature to estimate the burden (prevalence and incidence) of NTM in the cystic fibrosis population.

Methods

Electronic databases, registries and grey literature sources were searched for cohort and cross-sectional studies reporting epidemiological measures (incidence and prevalence) of NTM infection or NTM pulmonary disease in cystic fibrosis. The last search was conducted in September 2021; we included reports published since database creation and registry reports published since 2010. The methodological quality of studies was appraised with the Joanna Briggs Institute tool. A random effects meta-analysis was conducted to summarise the prevalence of NTM infection, and the remaining results are presented in a narrative synthesis.

Results

This review included 95 studies. All 95 studies reported on NTM infection, and 14 of these also reported on NTM pulmonary disease. The pooled estimate for the point prevalence of NTM infection was 7.9% (95% CI 5.1-12.0%). In meta-regression, sample size and geographical location of the study modified the estimate. Longitudinal analysis of registry reports showed an increasing trend in NTM infection prevalence between 2010 and 2019.

Conclusions

The overall prevalence of NTM infection in cystic fibrosis is 7.9% and is increasing over time based on international registry reports. Future studies should report screening frequency, microbial identification methods and incidence rates of progression from NTM infection to pulmonary disease.

High-quality read-based phasing of cystic fibrosis cohort informs genetic understanding of disease modification

Phasing of heterozygous alleles is critical for interpretation of cis-effects of disease-relevant variation. We sequenced 477 individuals with cystic fibrosis (CF) using linked-read sequencing, which display an average phase block N50 of 4.39 Mb. We use these samples to construct a graph representation of CFTR haplotypes, demonstrating its utility for understanding complex CF alleles. These are visualized in a Web app, CFTbaRcodes, that enables interactive exploration of CFTR haplotypes present in this cohort. We perform fine-mapping and phasing of the chr7q35 trypsinogen locus associated with CF meconium ileus, an intestinal obstruction at birth associated with more severe CF outcomes and pancreatic disease. A 20-kb deletion polymorphism and a PRSS2 missense variant p.Thr8Ile (rs62473563) are shown to independently contribute to meconium ileus risk (p = 0.0028, p = 0.011, respectively) and are PRSS2 pancreas eQTLs (p = 9.5 × 10⁻⁷ and p = 1.4 × 10⁻⁴, respectively), suggesting the mechanism by which these polymorphisms contribute to CF. The phase information from linked reads provides a putative causal explanation for variation at a CF-relevant locus, which also has implications for the genetic basis of non-CF pancreatitis, to which this locus has been reported to contribute.

Diagnostic agreement among experts assessing adults presenting with possible cystic fibrosis: need for improvement and implications for patient care

Background

Increasing awareness of milder presentations of cystic fibrosis (CF) and greater interest in non-CF bronchiectasis are likely to lead to more CF screening by respiratory clinicians. As a result, adults who may not strictly fulfil CF diagnostic criteria yet display evidence of abnormal CF transmembrane conductance regulator (CFTR) function are being identified. The degree of agreement on diagnosis and care needs in these cases between CF clinicians remains unknown, and has implications for patient care, including access to CFTR modulator therapies.

Methods

We surveyed adult CF physicians in Canada, the USA, the UK and Ireland, and presented them with anonymised vignettes of adult patients referred for assessment of possible CF. Diagnostic inter-rater agreement over diagnosis, ease of classifying cases and appropriate follow-up was assessed using Krippendorff's reliability coefficient (α).

Results

Agreement over diagnosis (α=0.282), ease of classification (α= -0.01) and recommended follow-up (α=0.054) was weak. Clinician experience (>10 and 5-10 years versus <5 years) and location (UK and Ireland versus Canada) were associated with higher odds of recommending further testing compared with selecting a formal diagnosis (respectively, OR 2.87; p=0.022, OR 3.74; p=0.013 and OR 3.16; p=0.007). A modified standard of care was recommended in 28.7% of cases labelled as CF. 70% of respondents agreed with the statement that "Accurate distinction between CF and CFTR-related disorder has become significantly more pertinent with the advent of highly effective CFTR modulators".

Conclusions

Our results demonstrate low diagnostic concordance among CF specialists assessing cases of possible adult CF and highlight an area in need of improvement.

Whole blood RNA-seq demonstrates an increased host immune response in individuals with cystic fibrosis who develop nontuberculous mycobacterial pulmonary disease

BACKGROUND

Individuals with cystic fibrosis have an elevated lifetime risk of colonization, infection, and disease caused by nontuberculous mycobacteria. A prior study involving non-cystic fibrosis individuals reported a gene expression signature associated with susceptibility to nontuberculous mycobacteria pulmonary disease (NTM-PD). In this study, we determined whether people living with cystic fibrosis who progress to NTM-PD have a gene expression pattern similar to the one seen in the non-cystic fibrosis population.

METHODS

We evaluated whole blood transcriptomics using bulk RNA-seq in a cohort of cystic fibrosis patients with samples collected closest in timing to the first isolation of nontuberculous mycobacteria. The study population included patients who did (n = 12) and did not (n = 30) develop NTM-PD following the first mycobacterial growth. Progression to NTM-PD was defined by a consensus of two expert clinicians based on reviewing clinical, microbiological, and radiological information. Differential gene expression was determined by DESeq2.

RESULTS

No differences in demographics or composition of white blood cell populations between groups were identified at baseline. Out of 213 genes associated with NTM-PD in the non-CF population, only two were significantly different in our cystic fibrosis NTM-PD cohort. Gene set enrichment analysis of the differential expression results showed that CF individuals who developed NTM-PD had higher expression levels of genes involved in the interferon (α and γ), tumor necrosis factor, and IL6-STAT3-JAK pathways.

CONCLUSION

In contrast to the non-cystic fibrosis population, the gene expression signature of patients with cystic fibrosis who develop NTM-PD is characterized by increased innate immune responses.

Pulmonary exacerbation inflammatory phenotypes in adults with cystic fibrosis

BACKGROUND

Adults with cystic fibrosis (CF) develop exuberant inflammatory responses during pulmonary exacerbations (PEx) but whether distinct systemic inflammatory profiles can be identified and whether these associate with disparate treatment outcomes are unclear. We conducted a pilot study to address this question and hypothesized that CF adults with a pauci-inflammatory phenotype might derive less clinical benefit from intravenous (IV) antibiotic treatment than patients with other systemic inflammatory phenotypes.

METHODS

Six proteins reflective of systemic inflammation were examined in 37 PEx from 28 unique CF subjects. We applied exploratory factor analysis and cluster analysis to identify biological clusters. Levels of blood proteins at PEx and clinical outcomes following IV antibiotic treatment were compared between clusters.

RESULTS

Three clusters of PEx were identified. The pauci-inflammatory phenotype was characterized by lower levels of interleukin (IL)-1β, IL-6, IL-10, tumor necrosis factor (TNF)-α, calprotectin, and C-reactive protein (CRP) (p < 0.05). Higher levels of IL-6 and IL-1β were observed in the other 2 inflammatory clusters, but one of them was associated with higher calprotectin levels (p = 0.001) (neutrophil-predominant phenotype); whereas the other was associated with increased TNF-α and IL-10 levels (p < 0.001) (pro-inflammatory phenotype). A greater proportion of events from the neutrophil-predominant phenotype presented with acute respiratory symptoms and a larger decrease in ppFEV₁ from baseline to hospital admission than the other two inflammatory phenotypes (p = 0.03).

CONCLUSIONS

Three distinct inflammatory phenotypes were identified at PEx admission and each presented with unique clinical characteristics.

Contemporary cystic fibrosis incidence rates in Canada and the United States

BACKGROUND

The availability of new diagnostic algorithms for cystic fibrosis (CF), changing population demographics and programs that impact family planning decisions can influence incidence rates. Thus, previously reported incidence rates in Canada and the United States (US) may be outdated. The objectives of this study were to estimate contemporary CF incidence rates in Canada and the US and to determine if the incidence rate has changed over time.

METHOD

This population-based cohort study utilized data between 1995-2019 from the Canadian CF Registry (CCFR), Statistics Canada, US CF Foundation Patient Registry (CFFPR) data, and US Center for Disease Control (CDC) National Vital Statistics System. Incidence was estimated using the number of live CF births by year, sex, and geographic region using Poisson regression, with the number of live births used as the denominator. To account for delayed diagnoses, we imputed the proportion of diagnoses expected given historical trends, and varying rates of newborn screening (NBS) implementation by region.

RESULTS

After accounting for implementation of NBS and delayed diagnoses, the estimated incidence rate for CF in 2019 was 1:3848 (95% CI: 1:3574, 1:4143) live births in Canada compared to 1:5130 (95% CI:1:4996, 1:5267) in the US. There was substantial regional variation in incidence rates within both Canada and the US. Since 1995, incidence rates have decreased at a rate of 1.6% per year in both countries (p<0.001).

CONCLUSION

Contemporary CF incidence rates suggest CF incidence is lower than previously reported and varies widely within North America. This information is important for resource planning and for tracking how programs (e.g., genetic counselling, modulator availability etc.) may impact the incidence of CF moving forward.

Acute Pulmonary Exacerbation Phenotypes in Patients with Cystic Fibrosis

Rationale: The etiology of cystic fibrosis (CF) pulmonary exacerbations (PEx) is likely multifactorial with viral, bacterial, and non-infectious pathways contributing. Objectives: To determine whether viral infection status and CRP (C-reactive protein) can classify subphenotypes of PEx that differ in outcomes and biomarker profiles. Methods: Patients were recruited at time of admission for a PEx. Nasal swabs and sputum samples were collected and processed using the respiratory panel of the FilmArray multiplex polymerase chain reaction (PCR). Serum and plasma biomarkers were measured. PEx were classified using serum CRP and viral PCR: "pauci-inflammatory" if CRP < 5 mg/L, "non-viral with systemic inflammation" if CRP ⩾ 5 mg/L and no viral infection detected by PCR and "viral with systemic inflammation" if CRP ⩾ 5 mg/L and viral infection detected by PCR. Results: Discovery cohort (n = 59) subphenotype frequencies were 1) pauci-inflammatory (37%); 2) non-viral with systemic inflammation (41%); and 3) viral with systemic inflammation (22%). Immunoglobulin G, immunoglobulin M, interleukin-10, interleukin-13, serum calprotectin, and CRP levels differed across phenotypes. Reduction from baseline in forced expiratory volume in 1 second as percent predicted (FEV₁pp) at onset of exacerbation differed between non-viral with systemic inflammation and viral with systemic inflammation (-6.73 ± 1.78 vs. -13.5 ± 2.32%; P = 0.025). Non-viral with systemic inflammation PEx had a trend toward longer duration of intravenous antibiotics versus pauci-inflammation (18.1 ± 1.17 vs. 14.8 ± 1.19 days, P = 0.057). There were no differences in percent with lung function recovery to <10% of baseline FEV₁pp. Similar results were seen in local and external validation cohorts comparing a pauci-inflammatory to viral/non-viral inflammatory exacerbation phenotypes. Conclusions: Subphenotypes of CF PEx exist with differences in biomarker profile, clinical presentation, and outcomes.

Increased versus stable doses of inhaled corticosteroids for exacerbations of chronic asthma in adults and children

BACKGROUND

People with asthma may experience exacerbations, or 'attacks', during which their symptoms worsen and additional treatment is required. Written action plans sometimes advocate a short-term increase in the dose of inhaled corticosteroids (ICS) at the first sign of an exacerbation to reduce the severity of the attack and to prevent the need for oral steroids or hospital admission.

OBJECTIVES

To compare the clinical effectiveness and safety of increased versus stable doses of ICS as part of a patient-initiated action plan for the home management of exacerbations in children and adults with persistent asthma.

SEARCH METHODS

We searched the Cochrane Airways Group Specialised Register, which is derived from searches of the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, and CINAHL (Cumulative Index to Nursing and Allied Health Literature), and handsearched abstracts to 20 December 2021. We also searched major trial registries for ongoing trials.

SELECTION CRITERIA

We included parallel and cross-over randomised controlled trials (RCTs) that allocated people with persistent asthma to take a blinded inhaler in the event of an exacerbation which either increased their daily dose of ICS or kept it stable (placebo).

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials, assessed quality, and extracted data. We reassessed risk of bias for all studies at the result level using the revised risk of bias tool for RCTs (Risk of Bias 2), and employed the GRADE approach to assess our confidence in the synthesised effect estimates. The primary outcome was treatment failure, defined as the need for rescue oral steroids in the randomised population. Secondary outcomes were treatment failure in the subset who initiated the study inhaler (treated population), unscheduled physician visits, unscheduled acute care, emergency department or hospital visits, serious and non-serious adverse events, and duration of exacerbation.

MAIN RESULTS

This review update added a new study that increased the number of people in the primary analysis from 1520 to 1774, and incorporates the most up-to-date methods to assess the likely impact of bias within the meta-analyses. The updated review now includes nine RCTs (1923 participants; seven parallel and two cross-over) conducted in Europe, North America, and Australasia and published between 1998 and 2018. Five studies evaluated adult populations (n = 1247; ≥ 15 years), and four studies evaluated child or adolescent populations (n = 676; < 15 years). All study participants had mild to moderate asthma. Studies varied in the dose of maintenance ICS, age, fold increase of ICS in the event of an exacerbation, criteria for initiating the study inhaler, and allowed medications. Approximately 50% of randomised participants initiated the study inhaler (range 23% to 100%), and the included studies reported treatment failure in a variety of ways, meaning assumptions were required to permit the combining of data. Participants randomised to increase their ICS dose at the first signs of an exacerbation had similar odds of needing rescue oral corticosteroids to those randomised to a placebo inhaler (odds ratio (OR) 0.97, 95% confidence interval (CI) 0.76 to 1.25; 8 studies; 1774 participants; I2 = 0%; moderate quality evidence). We could draw no firm conclusions from subgroup analyses conducted to investigate the impact of age, time to treatment initiation, baseline dose, smoking history, and fold increase of ICS on the primary outcome. Results for the same outcome in the subset of participants who initiated the study inhaler were unchanged from the previous version, which provides a different point estimate with very low confidence due to heterogeneity, imprecision, and risk of bias (OR 0.84, 95% CI 0.54 to 1.30; 7 studies; 766 participants; I2 = 42%; random-effects model). Confidence was reduced due to risk of bias and assumptions that had to be made to include study data in the intention-to-treat and treated-population analyses. Sensitivity analyses that tested the impact of assumptions made for synthesis and to exclude cross-over studies, studies at overall high risk of bias, and those with commercial funding did not change our conclusions. Pooled effects for unscheduled physician visits, unscheduled acute care, emergency department or hospital visits, and duration of exacerbation made it very difficult to determine where the true effect may lie, and confidence was reduced by risk of bias. Point estimates for both serious and non-serious adverse events favoured keeping ICS stable, but imprecision and risk of bias due to missing data and outcome measurement and reporting reduced our confidence in the effects (serious adverse events: OR 1.69, 95% CI 0.77 to 3.71; 2 studies; 394 participants; I² = 0%; non-serious adverse events: OR 2.15, 95% CI 0.68 to 6.73; 2 studies; 142 participants; I² = 0%).

AUTHORS' CONCLUSIONS

Evidence from double-blind trials of adults and children with mild to moderate asthma suggests there is unlikely to be an important reduction in the need for oral steroids from increasing a patient's ICS dose at the first sign of an exacerbation. Other clinically important benefits and potential harms of increased doses of ICS compared with keeping the dose stable cannot be ruled out due to wide confidence intervals, risk of bias in the trials, and assumptions that had to be made for synthesis. Included studies conducted between 1998 and 2018 reflect evolving clinical practice and study methods, and the data do not support thorough investigation of effect modifiers such as baseline dose, fold increase, asthma severity and timing. The review does not include recent evidence from pragmatic, unblinded studies showing benefits of larger dose increases in those with poorly controlled asthma. A systematic review is warranted to examine the differences between the blinded and unblinded trials using robust methods for assessing risk of bias to present the most complete view of the evidence for decision makers.

Metabolomic Biomarkers to Predict and Diagnose Cystic Fibrosis Pulmonary Exacerbations: A Systematic Review

INTRODUCTION

Metabolomics is an emerging area of research and has the potential to identify clinical biomarkers for predicting or diagnosing cystic fibrosis (CF) pulmonary exacerbations (PEx).

OBJECTIVE

To identify clinically promising metabolites across different sample sources that can be used to predict or diagnose PEx in CF.

EVIDENCE REVIEW

Searches for original literature were completed through EMBASE, MEDLINE, and all databases on the Web of Science with no restrictions on language or publication date. Gray literature was collected through Google Scholar. Additional studies were obtained by contacting authors and searching reference lists of candidate papers. The patient population included individuals with CF. Studies involving patients who underwent lung transplantation were excluded. The outcome was the prediction or diagnosis of pulmonary exacerbations from metabolites directly measured from biological samples. Search results were downloaded and imported into Covidence and duplicates were removed automatically. Any remaining duplicates were manually tagged and excluded. Two independent reviewers screened each abstract for eligibility and repeated this process for full texts. Risk of bias was conducted using QUADAS-2 by two independent reviewers. A third author resolved any remaining conflicts.

RESULTS

A combined 3974 relevant abstracts were identified and 115 full texts were assessed for eligibility. The final 25 studies underwent data extraction for study design, patient demographics, studied metabolites, concentration values, and diagnostic accuracy values. Included studies differed considerably in methodologies, sample specimen types (exhaled breath condensate [EBC], sputum, saliva, plasma, urine), and disease states. We identified 19 unique metabolites that were measured by two or more studies of which 2 have the potential to predict PEx (EBC 4-hydroxycyclohexylcarboxylic acid [4-HCHC] and lactic acid) and 6 to diagnose PEx (EBC 4-HCHC and lactic acid, sputum lactic acid and nitrate, and plasma arginine and methionine).

CONCLUSION AND RELEVANCE

This systematic review has identified promising metabolites for further study in CF. Certain metabolites may provide clinical potential in predicting or diagnosing PEx, but further validation studies are required. With better tools to aid in the earlier identification of PEx, clinicians can implement preventative measures to mitigate airway damage.Systematic Review Registration: https://www.crd.york.ac.uk/prospero/.

The prevalence of CFTR mutations in patients with chronic rhinosinusitis: A systematic review and meta-analysis

OBJECTIVES

Undetected cystic fibrosis transmembrane regulator (CFTR) mutations may predispose individuals to develop CRS independent of formal CF diagnosis. The objective of this study was to determine the prevalence of CFTR mutations among individuals with CRS.

DESIGN

A systematic search following PRISMA guidelines was performed. A meta-analysis was performed to calculate pooled estimates for the prevalence of any CFTR mutation and for the DF508 mutation.

SETTING AND PARTICIPANTS

The systematic search included all studies identifying adults diagnosed with CRS, with no limitation to region or publication date. Studies had to identify a sample of patients previously diagnosed with CRS but not with CF and reporting testing for the prevalence of CF or the CFTR gene mutation.

MAIN OUTCOME MEASURES

Prevalence of CFTR mutations among the general CRS population, with subgroup analysis of individuals with the dF508 mutation.

RESULTS AND CONCLUSIONS

The 6 included studies represented five countries: the United States, the UK, France, Poland and Finland. The pooled prevalence of CFTR mutations of any kind in CRS subjects without CF was 5.65% (RE 95% CI 2.99 - 10.41). The overall prevalence for the dF508 mutation was 4.22% (RE 95% CI 1.71 - 10.07). These estimates were significantly higher than the baseline estimated prevalence of CFTR carrier status of 3%-4% in the general population. However, the clinical relevance of the presence of CFTR mutations in CRS patients who have not been diagnosed with CF is currently unclear. Future studies should include sweat chloride testing as a measure of CFTR function.

Clinician variability in the diagnosis and treatment of aspergillus fumigatus-related conditions in cystic fibrosis: An international survey

BACKGROUND

The diagnosis and treatment of Aspergillus fumigatus (Af)-related conditions remain a challenge in cystic fibrosis (CF) due to overlapping features of disease and absence of clinical guidelines for Af-related conditions outside of ABPA.

OBJECTIVE

To investigate the differences of clinical practice in the diagnosis and management of Af-related conditions in CF.

METHODS

We conducted an international survey to CF clinicians to ascertain the screening, diagnostic, and treatment practices for Af-related conditions in CF. Respondents were grouped into geographical regions and regional comparisons using chi-square tests of independence or Fisher's tests were performed.

RESULTS

A total of 319 survey responses from 35 countries were analyzed. We observed differences in use and frequency of fungus culture, Aspergillus-specific IgE and IgG, skin prick testing, and pulmonary function testing as screening for Af-related conditions between the geographical regions. ABPA and Aspergillus bronchitis diagnostic criteria selection differed by region; significantly greater proportion of United States (US) and Canadian clinicians were unable to define Aspergillus bronchitis compared to Europe and other regions. Decision to treat ABPA was uniform across regions, but the consideration of Aspergillus bronchitis as a clinical disease warranting therapy differed between regions. The use of glucocorticoid and itraconazole was the first-line treatment of ABPA among clinicians; however, prednisone monotherapy was more common in US and Canada.

CONCLUSIONS

Significant variability in the diagnosis and management of Aspergillus-related conditions in CF was observed. Future studies are necessary to better harmonize the approach to Af-related disease in CF.

Survival and Lung Transplant Outcomes for Individuals With Advanced Cystic Fibrosis Lung Disease Living in the United States and Canada: An Analysis of National Registries

BACKGROUND

Understanding how health outcomes differ for patients with advanced cystic fibrosis (CF) lung disease living in the United States compared with Canada has health policy implications.

RESEARCH QUESTION

What are rates of lung transplant (LTx) and rates of death without LTx in the United States and Canada among individuals with FEV₁ < 40% predicted?

STUDY DESIGN AND METHODS

This was a retrospective population-based cohort study, 2005 to 2016, using the US CF Foundation, United Network for Organ Sharing, and Canadian CF registries. Individuals with CF and at least two FEV₁ measurements < 40% predicted within a 5-year period, age ≥ 6 years, without prior LTx were included. Multivariable competing risk regression for time to death without LTx (LTx as a competing risk) and time to LTx (death as a competing risk) was performed.

RESULTS

There were 5,899 patients (53% male) and 905 patients (54% male) with CF with FEV₁ < 40% predicted living in the United States and Canada, respectively. Multivariable competing risk regression models identified an increased risk of death without LTx (hazard ratio [HR], 1.79; 95% CI, 1.52-2.1) and decreased LTx (HR, 0.66; 95% CI, 0.58-0.74) among individuals in the United States compared with Canada. More pronounced differences were seen in the patients in the United States with Medicaid/Medicare insurance compared with Canadians (multivariable HR for death without LTx, 2.24 [95% CI, 1.89-2.64]; multivariable HR for LTx, 0.54 [95% CI, 0.47-0.61]). Patients of nonwhite race were also disadvantaged (multivariable HR for death without LTx, 1.56 [95% CI, 1.32-1.84]; multivariable HR for LTx, 0.47 [95% CI, 0.36-0.62]).

INTERPRETATION

There are lower rates of LTx and an increased risk of death without LTx for US patients with CF with FEV₁ < 40% predicted compared with Canadian patients. Findings are more striking among US patients with CF with Medicaid/Medicare health insurance, and nonwhite patients in both countries, raising concerns about underuse of LTx among vulnerable populations.

Effect of endoscopic sinus surgery on clinical outcomes in DeltaF508 cystic fibrosis patients

OBJECTIVES

Chronic rhinosinusitis (CRS) is prevalent in the Cystic Fibrosis (CF) population. CRS exacerbations in CF are thought to contribute to pulmonary exacerbations. Literature regarding the impact of endoscopic sinus surgery (ESS) is inconclusive. This study examines rates of lung function decline and pulmonary exacerbation in CF patients who have undergone ESS.

DESIGN

Retrospective review of medical records.

SETTING

Academic Hospital.

PARTICIPANTS

40 adult CF patients.

MAIN OUTCOME MEASURES

Rate of lung function decline (% predicted Forced Expiratory Volume in 1 second [ppFEV₁ ]), number of pulmonary exacerbations (IV/oral antibiotic therapy ± hospital admission) and total number days hospitalised 2-year postoperatively was collected. CRS patients undergoing ESS were matched to those without ESS by gender, age, and F508del genotype.

RESULTS

Forty patients (mean age 37.4, 60% male) were reviewed. No significant difference was found between the surgical group and controls in baseline ppFEV₁ (72.5% vs. 72.7%, P = .98), 2-year preoperative number of pulmonary exacerbations (3.05 vs. 1.65, P = .10), or Lund-Mackay scores (12.25 vs. 11.55, P = .71). No significant difference was found in 1-year (70.5% vs. 72.8%, P = .84) or 2-year (70.4% vs. 72.6% P = .80) postoperative ppFEV₁ and 2-year postoperative pulmonary exacerbations (1.7 vs. 1.45, P = .87). A significant increase was identified in total number days hospitalised postoperatively (4.85, P = .02). In the surgical group, no significant difference was identified between preoperative and postoperative ppFEV₁ , 1 year (-2.51%, P = .32) and 2 years after ESS (-3.10%, P = .51), postoperative rate of pulmonary exacerbations (-1.28, P = .11), or in total number days hospitalised (3.74, P = .14).

CONCLUSIONS

In this study, ESS does not appear to significantly improve ppFEV₁ or decrease the number of pulmonary exacerbations postoperatively.

Bridging the survival gap in cystic fibrosis: An investigation of lung transplant outcomes in Canada and the United States

BACKGROUND

Previous literature in cystic fibrosis (CF) has shown a 10-year survival gap between Canada and the United States (US). We hypothesized that differential access to and survival after lung transplantation may contribute to the observed gap. The objectives of this study were to compare CF transplant outcomes between Canada and the US and estimate the potential contribution of transplantation to the survival gap.

METHODS

Data from the Canadian CF Registry and the US Cystic Fibrosis Foundation Patient Registry supplemented with data from United Network for Organ Sharing were used. The probability of surviving after transplantation between 2005 and 2016 was calculated using the Kaplan‒Meier method. Survival by insurance status at the time of transplantation and transplant center volume in the US were compared with those in Canada using Cox proportional hazard models. Simulations were used to estimate the contribution of transplantation to the survival gap.

RESULTS

Between 2005 and 2016, there were 2,653 patients in the US and 470 in Canada who underwent lung transplantation for CF. The 1-, 3-, and 5-year survival rates were 88.3%, 71.8%, and 60.3%, respectively, in the US compared with 90.5%, 79.9%, and 69.7%, respectively, in Canada. Patients in the US were also more likely to die on the waitlist (p < 0.01) than patients in Canada. If the proportion of who underwent transplantation and post-transplant survival in the US were to increase to those observed in Canada, we estimate that the survival gap would decrease from 10.8 years to 7.5 years.

CONCLUSIONS

Differences in waitlist mortality and post-transplant survival can explain up to a third of the survival gap observed between the US and Canada.

Sex disparities in cystic fibrosis: review on the effect of female sex hormones on lung pathophysiology and outcomes

Sex differences in morbidity and mortality have been reported in the cystic fibrosis (CF) population worldwide. However, it is unclear why CF women have worse clinical outcomes than men. In this review, we focus on the influence of female sex hormones on CF pulmonary outcomes and summarise data from in vitro and in vivo experiments on how oestrogen and progesterone might modify mucociliary clearance, immunity and infection in the CF airways. The potential for novel sex hormone-related therapeutic interventions is also discussed.

A disparity in survival has been noted between men and women with cystic fibrosis where female sex hormones may facilitate lung disease progression. There is strong evidence that implicates oestrogen in numerous aspects of CF airway pathophysiology.https://bit.ly/34ef4Cv

Cystic fibrosis-related diabetes onset can be predicted using biomarkers measured at birth

Purpose

Cystic fibrosis (CF), caused by pathogenic variants in the CF transmembrane conductance regulator (CFTR), affects multiple organs including the exocrine pancreas, which is a causal contributor to cystic fibrosis–related diabetes (CFRD). Untreated CFRD causes increased CF-related mortality whereas early detection can improve outcomes.

Methods

Using genetic and easily accessible clinical measures available at birth, we constructed a CFRD prediction model using the Canadian CF Gene Modifier Study (CGS; n = 1,958) and validated it in the French CF Gene Modifier Study (FGMS; n = 1,003). We investigated genetic variants shown to associate with CF disease severity across multiple organs in genome-wide association studies.

Results

The strongest predictors included sex, CFTR severity score, and several genetic variants including one annotated to PRSS1, which encodes cationic trypsinogen. The final model defined in the CGS shows excellent agreement when validated on the FGMS, and the risk classifier shows slightly better performance at predicting CFRD risk later in life in both studies.

Conclusion

We demonstrated clinical utility by comparing CFRD prevalence rates between the top 10% of individuals with the highest risk and the bottom 10% with the lowest risk. A web-based application was developed to provide practitioners with patient-specific CFRD risk to guide CFRD monitoring and treatment.

Factors influencing clinical trial participation for adult and pediatric patients with cystic fibrosis

There remains a limited understanding of the factors influencing clinical trial participation for individuals with Cystic Fibrosis (CF). A comprehensive survey was developed to examine the interests, preferences, and barriers/facilitators to research and clinical trial participation for CF patients. A consecutive sample of 198 CF adults attending the St. Paul's Hospital CF Clinic and parents of children with CF attending the BC Children's Hospital CF Clinic from Vancouver, Canada were surveyed. Parents of pediatric patients were less comfortable with blood collection, required more safety data prior to participating, and were more concerned about potential side effects. Very few respondents (<10%) appeared able/willing to fulfill the typical requirements to participate in a phase 1 clinical trial. Overall, there were more similarities than differences between the responses of adult and parents of pediatric CF patients. The patient-centered information can be used to inform the design of future clinical trials to enhance feasibility.

Worsening pulmonary outcomes during sex reassignment therapy in a transgender female with cystic fibrosis (CF) and asthma/allergic bronchopulmonary aspergillosis: a case report

Background

Cystic Fibrosis (CF) is a hereditary pulmonary and extra-pulmonary disease that occurs equally in men and women. However, a difference in morbidity and mortality rates between the sexes has been long documented. Similarly, a sex-disparity in disease severity has been reported in asthma as well. Studies done to date point to estrogen as a possible cause of this sex disparity in pulmonary outcomes in both conditions.

Case presentation

Here, we describe a case of a patient with CF and asthma/allergic bronchopulmonary aspergillosis (ABPA) undergoing sex reassignment therapy (male-to-female) and the negative impact it had on her lung function and frequency of pulmonary exacerbations in the context of increasing doses of exogenous estrogen.

Conclusions

This case raises the possibility of a link between estrogen and worsening pulmonary outcomes and the need for further studies into transgender individuals with CF and/or asthma/ABPA as well as those undergoing high dose estrogen therapy for other indications.

Building global development strategies for cf therapeutics during a transitional cftr modulator era

As CFTR modulator therapy transforms the landscape of cystic fibrosis (CF) care, its lack of uniform access across the globe combined with the shift towards a new standard of care creates unique challenges for the development of future CF therapies. The advancement of a full and promising CF therapeutics pipeline remains a necessary priority to ensure maximal clinical benefits for all people with CF. It is through collaboration across the global CF community that we can optimize the evaluation and approval process of new therapies. To this end, we must identify areas for which harmonization is lacking and for which efficiencies can be gained to promote ethical, feasible, and credible study designs amidst the changing CF care landscape. This article summarizes the counsel from core advisors across multiple international regions and clinical trial networks, developed during a one-day workshop in October 2019. The goal of the workshop was to identify, in consideration of the highly transitional era of CFTR modulator availability, the drug development areas for which global alignment is currently uncertain, and paths forward that will enable advancement of CF therapeutic development.

Short-term effects of Lumacaftor/Ivacaftor (Orkambi™) on exertional symptoms, exercise performance, and ventilatory responses in adults with cystic fibrosis

RATIONALE

Lumacaftor/ivacaftor (LUM/IVA) modestly improves lung function following 1 month of treatment but it is unknown if this translates into improvements in exercise endurance and exertional symptoms.

METHODS

Adult CF participants completed a symptom-limited constant load cycling test with simultaneous assessments of dyspnea and leg discomfort ratings pre- and 1 month post-initiation of LUM/IVA.

RESULTS

Endurance time, exertional dyspnea and leg discomfort ratings at submaximal exercise did not change significantly. There was a significant inverse correlation between changes in leg discomfort and endurance time (r = - 0.88; p = 0.009) following 1-month of LUM/IVA.

CONCLUSIONS

Overall, 1-month of LUM/IVA did not increase endurance time or modify exertional dyspnea or leg discomfort ratings. However, individuals who experienced a reduction in leg discomfort following LUM/IVA had an improvement in endurance time. Future studies with a larger sample size are needed to verify these findings and to assess the long-term effects of LUM/IVA on exercise outcomes.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02821130. Registered July 1, 2016.

Circulating CRP and calprotectin to diagnose CF pulmonary exacerbations

Cystic fibrosis (CF) pulmonary exacerbations (PEx) remain underdiagnosed by CF clinicians. Serum C-reactive protein (CRP) and calprotectin are inflammatory biomarkers that have the potential to aid in the diagnosis of PEx. 19 subjects (56 stable, 46 PEx visits) from a longitudinal study were included and the diagnostic performance of absolute and fold-change CRP and calprotectin cut-offs to discriminate stable and PEx visits was assessed. Based on Youden's index, optimal absolute and fold-change thresholds to identify PEx were 9.5 mg/L (Sn 76%, Sp 73%; AUC 0.76) and 2.2-fold (Sn 50%, Sp 96%; AUC 0.78) for CRP and 8.1 mg/L (Sn 61%, Sp 79%; AUC 0.72) and 1.3-fold (Sn 57%, Sp 88%; AUC 0.74) for calprotectin. A step-wise algorithm was able to improve diagnostic performance (Sn 80%; Sp 88%). CRP and calprotectin could discriminate stable vs. PEx visits with good performance and appear promising as diagnostic biomarkers but further validation studies are required prior to implementing these diagnostic thresholds.

Immunomodulatory function of the cystic fibrosis modifier gene BPIFA1

BACKGROUND

Cystic fibrosis (CF) is characterized by a progressive decline in lung function due to airway obstruction, infection, and inflammation. CF patients are particularly susceptible to respiratory infection by a variety of pathogens, and the inflammatory response in CF is dysregulated and prolonged. BPI fold containing family A, member 1 (BPIFA1) and BPIFB1 are proteins expressed in the upper airways that may have innate immune activity. We previously identified polymorphisms in the BPIFA1/BPIFB1 region associated with CF lung disease severity.

METHODS

We evaluated whether the BPIFA1/BPIFB1 associations with lung disease severity replicated in individuals with CF participating in the International CF Gene Modifier Consortium (n = 6,365). Furthermore, we investigated mechanisms by which the BPIFA1 and BPIFB1 proteins may modify lung disease in CF.

RESULTS

The association of the G allele of rs1078761 with reduced lung function was replicated in an independent cohort of CF patients (p = 0.001, n = 2,921) and in a meta-analysis of the full consortium (p = 2.39x10-5, n = 6,365). Furthermore, we found that rs1078761G which is associated with reduced lung function was also associated with reduced BPIFA1, but not BPIFB1, protein levels in saliva from CF patients. Functional assays indicated that BPIFA1 and BPIFB1 do not have an anti-bacterial role against P. aeruginosa but may have an immunomodulatory function in CF airway epithelial cells. Gene expression profiling using RNAseq identified Rho GTPase signaling pathways to be altered in CF airway epithelial cells in response to treatment with recombinant BPIFA1 and BPIFB1 proteins.

CONCLUSIONS

BPIFA1 and BPIFB1 have immunomodulatory activity and genetic variation associated with low levels of these proteins may increase CF lung disease severity.

A Systematic Review of the Clinical Efficacy and Safety of CFTR Modulators in Cystic Fibrosis

Several placebo-controlled trials have been recently published evaluating novel therapies targeting the defective CFTR protein. This systematic review examines the clinical efficacy and safety of CFTR modulators in individuals with cystic fibrosis (CF) with specific genetic mutations. Online sources were searched for placebo-controlled, parallel-design clinical trials investigating CFTR modulators from January 1, 2005 to March 31, 2018. The primary outcome of interest was FEV₁% predicted (ppFEV₁). Fourteen RCTs met our eligibility criteria. The largest improvement in ppFEV₁ favouring treatment was observed for ivacaftor (IVA) in G551D individuals (≥6 years old). Both tezacaftor-ivacaftor (TEZ-IVA) and lumacaftor-ivacaftor (LUM-IVA) also improved ppFEV₁ in F508del homozygous individuals but there was increased reporting of respiratory adverse events with LUM-IVA compared to placebo. IVA also significantly improved ppFEV₁ in a sub-group of individuals ≥18 years old with an R117H mutation. No significant improvements in ppFEV₁ were observed for IVA, LUM, or TEZ in F508del homozygous individuals, LUM or LUM-IVA in F508del heterozygous individuals, or ataluren in individuals with a nonsense mutation. Significant improvements in ppFEV₁ and other clinical outcomes were observed for IVA in G551D individuals, TEV-IVA and LUM-IVA in F508del homozygous individuals, and IVA in adults with a R117H mutation.

The effects of cycled inhaled aztreonam on the cystic fibrosis (CF) lung microbiome

BACKGROUND

To improve clinical outcomes, cystic fibrosis (CF) patients with chronic Pseudomonas aeruginosa infections are prescribed inhaled anti-pseudomonal antibiotics. Although, a diverse microbial community exists within CF airways, little is known about how the CF microbiota influences patient outcomes. We hypothesized that organisms within the CF microbiota are affected by inhaled-antibiotics and baseline microbiome may be used to predict therapeutic response.

METHODS

Adults with chronic P. aeruginosa infection from four clinics were observed during a single 28-day on/off inhaled-aztreonam cycle. Patients performed serial sputum collection, CF-respiratory infection symptom scores (CRISS), and spirometry. Patients achieving a decrease of ≥2 CRISS by day 28 were categorized as subjective responders (SR). The airway microbiome was defined by Illumina MiSeq analysis of the 16S rRNA gene.

RESULTS

Thirty-seven patients (median 37.4 years and FEV₁ 44% predicted) were enrolled. No significant cohort-wide changes in the microbiome were observed between on/off AZLI cycles in either alpha- or beta-diversity metrics. However, at an individual level shifts were apparent. Twenty-one patients (57%) were SR and fourteen patients did not subjectively respond. While alpha-diversity metrics did not associate with response, patients who did not subjectively respond had a higher abundance of Staphylococcus and Streptococcus, and lower abundance of Haemophilus.

CONCLUSIONS

The CF microbiome is relatively resilient to AZLI perturbations. However, associated changes were observed at the individual patient level. The relative abundance of key "off-target" organisms associated with subjective improvements suggesting that the microbiome may be used as a tool to predict patient response - potentially improving outcomes.

Recent advances in the understanding and management of cystic fibrosis pulmonary exacerbations

Pulmonary exacerbations are common events in cystic fibrosis and have a profound impact on quality of life, morbidity, and mortality. Pulmonary exacerbation outcomes remain poor and a significant proportion of patients fail to recover their baseline lung function despite receiving aggressive treatment with intravenous antibiotics. This focused review provides an update on some of the recent advances that have taken place in our understanding of the epidemiology, pathophysiology, diagnosis, and management of pulmonary exacerbations in cystic fibrosis as well as direction for future study.

Comparison of Nutrition and Lung Function Outcomes in Patients with Cystic Fibrosis Living in Canada and the United States

RATIONALE

A 10-year gap in the median age of survival for patients with cystic fibrosis (CF) was reported between patients living in Canada compared with patients living in the United States.

OBJECTIVES

Because both malnutrition and poor lung function are associated with an increased risk of mortality in CF, we investigated the temporal and longitudinal trends in lung function and nutrition between Canada and the United States.

METHODS

This cohort study used Canadian CF Registry and U.S. CF Foundation Patient Registry data from 1990 to 2013. A unified dataset was created to harmonize the variables collected within the two registries for the purpose of comparing outcomes between the two countries.

MEASUREMENTS AND MAIN RESULTS

We conducted three analyses: survival differences by birth cohort; population trends for FEV1 and body mass index (BMI) over time; and individual patient FEV1 and BMI trajectories. The study included a total of 37,772 patients in the United States and 5,149 patients in Canada. Patients with CF experienced significant improvements in nutritional status and lung function in both Canada and the United States during the study. In addition, the survival gap between the two countries is narrowing within younger birth cohorts. The improvements for the patients within the United States were most prominent in the BMI trajectories, where patients born after 1990 in the United States have higher BMI that has persisted over time.

CONCLUSIONS

The reasons for the observed improvements, and catch-up in the United States, are likely multifactorial and include the introduction of high-fat, high-calorie diets; introduction of newborn screening; and/or improved access to care for CF children in the United States.

Clinical characteristics of cystic fibrosis patients prior to lung transplantation: An international comparison between Canada and the United States

BACKGROUND

Cystic fibrosis (CF) patients from Canada have better-reported post-lung transplant survival compared to patients from the United States. We hypothesized the clinical characteristics of CF patients prior to lung transplant differ between the two countries.

METHODS

Population-based cohort study utilizing combined Canadian CF Registry and US CF Foundation Patient Registry data from 1986 to 2013. Demographic and clinical variables were analyzed prior to lung transplant.

RESULTS

Between 1986 and 2013, 607 (10.2%) CF patients underwent lung transplantation in Canada and 3428 (7.5%) in the United States. A lower proportion of recipients had growth of B. cepacia complex prior to transplant in the United States compared to Canada (0.8% vs 4.3%). Lung function was similar between recipients from the two countries. The proportion of patients classified as underweight was significantly higher in the United States compared to Canada (39.8% vs 28.0%; SD 26.1) despite higher rates of feeding tube use (42.5% vs 28.6%; SD 29.0).

CONCLUSIONS

CF lung transplant recipients from the United States have similar lung function, lower rates of B. cepacia complex, and worse nutritional parameters prior to transplant compared to counterparts in Canada. Future studies are necessary to evaluate the impact of these differences on post-transplant survival.