CFTR genotype as a predictor of prognosis in cystic fibrosis

Factors influencing treatment response of pulmonary exacerbation in children with cystic fibrosis

BACKGROUND

Pulmonary exacerbations in cystic fibrosis (CF) significantly impact morbidity and mortality. This study aimed to assess treatment response rates and identify contributing factors towards treatment response.

METHODS

In this single-center, retrospective, longitudinal study spanning four years, we analyzed all pulmonary exacerbation admissions. We compared lung function at baseline, admission, end of treatment, and 6-week follow-up. Treatment response was defined as ≥95% recovery of baseline FEV1%.

RESULTS

There were 78 children who required a total of 184 admissions. The mean duration of treatment was 14.9±2.9 days. FEV1% returned to 95% of baseline in 59% following treatment. The magnitude of the decline in lung function on admission in children who did not respond to treatment was 21.7±15.2% while the decline in children who responded to treatment was 8.3±9.4%, P<0.001. Children who experienced a decline in FEV1% greater than 40% exhibited an 80% reduced likelihood of returning to their baseline values (OR -0.8, 95% CI -0.988; -0.612). Similarly, those with FEV1% reductions in the ranges of 30-39% (OR -0.63, 95% CI -0.821; -0.439), 20-29% (OR -0.52, 95% CI -0.657; -0.383), and 10-19% (OR -0.239, 95% CI -0.33; -0.148) showed progressively lower odds of returning to baseline. Fourty-eight children required readmission within 7.7±5.4 months, children who responded to treatment had a longer time taken to readmission (8.9±6.4 months) versus children who did not respond to treatment (6.4±3.5 months), (OR: -0.20, 95% CI -0.355; -0.048).

CONCLUSIONS

A greater decline in lung function on admission and readmission within 6 months of the initial admission predicts non-response to treatment. This highlights the importance of re-evaluating follow-up strategies following discharge.

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.

Impact of intrinsic and extrinsic risk factors on early-onset lung disease in cystic fibrosis

BACKGROUND

Although respiratory pathology is known to develop in young children with cystic fibrosis (CF), the determinants of early-onset lung disease have not been elucidated.

OBJECTIVE

We aimed to determine the impact of potential intrinsic and extrinsic risk factors during the first 3 years of life, testing the hypothesis that both contribute significantly to early-onset CF lung disease.

DESIGN

We studied 104 infants born during 2012-2017, diagnosed through newborn screening by age 3 months, and evaluated comprehensively to 36 months of age. Lung disease manifestations were quantified with a new scoring system known as CFELD for Cystic Fibrosis Early-onset Lung Disease. The variants in the cystic fibrosis transmembrane conductance regulator (CFTR) gene were determined and categorized. Whole genome sequencing was performed on each subject and the data transformed to polygenic risk scores (PRS) that aggregate variants associated with lung function. Extrinsic factors included socioeconomic status (SES) indicators and environmental experiences such as exposures to smoking, pets, and daycare.

RESULTS

We found by univariate analysis that CFTR genotype and genetic modifiers aggregated by the PRS method were significantly associated with early-onset CF lung disease. Ordinal logistic regression analysis demonstrated that high and stable SES (maternal education ≥community college, stable 2-parent home, and not receiving Medicaid) and better growth (weight-for-age and height-for-age z-scores) reduced risks, while exposure to smoking and daycare ≥20 h/week increased the risk of CFELD severity.

CONCLUSIONS

Extrinsic, modifiable determinants are influential early and potentially as important as the intrinsic risk factors in the onset of CF lung disease.

Nonsense mutations accelerate lung disease and decrease survival of cystic fibrosis children

RATIONALE

Limited information is available on the clinical status of people with Cystic Fibrosis (pwCF) carrying 2 nonsense mutations (PTC/PTC). The main objective of this study was to compare disease severity between pwCF PTC/PTC, compound heterozygous for F508del and PTC (F508del/PTC) and homozygous for F508del (F508del+/+).

METHODS

Based on the European CF Society Patient Registry clinical data of pwCF living in high and middle income European and neighboring countries, PTC/PTC (n = 657) were compared with F508del+/+ (n = 21,317) and F508del/PTC(n = 4254).CFTR mRNA and protein activity levels were assessed in primary human nasal epithelial (HNE) cells sampled from 22 PTC/PTC pwCF.

MAIN RESULTS

As compared to F508del+/+ pwCF; both PTC/PTC and F508del/PTC pwCF exhibited a significantly faster rate of decline in Forced Expiratory Volume in 1 s (FEV1) from 7 years (-1.33 for F508del +/+, -1.59 for F508del/PTC; -1.65 for PTC/PTC, p < 0.001) until respectively 30 years (-1.05 for F508del +/+, -1.23 for PTC/PTC, p = 0.048) and 27 years (-1.12 for F508del +/+, -1.26 for F508del/PTC, p = 0.034). This resulted in lower FEV1 values in adulthood. Mortality of pediatric pwCF with one or two PTC alleles was significantly higher than their F508del homozygous pairs. Infection with Pseudomonas aeruginosa was more frequent in PTC/PTC versus F508del+/+ and F508del/PTC pwCF. CFTR activity in PTC/PTC pwCF's HNE cells ranged between 0% to 3% of the wild-type level.

CONCLUSIONS

Nonsense mutations decrease the survival and accelerate the course of respiratory disease in children and adolescents with Cystic Fibrosis.

Association between unplanned pregnancies and maternal exacerbations in cystic fibrosis

INTRODUCTION

Following availability of the highly effective cystic fibrosis (CF) transmembrane conductance regulator modulator, elexacaftor/tezacaftor/ivacaftor, there was a near doubling of pregnancies reported in the United States (US) in people with CF. We sought to determine health impacts of planned (PP) versus unplanned pregnancies (UP).

METHODS

We collected retrospective pregnancy data from January 2010-December 2020 from 11 US CF centers. After adjusting for potential confounding effects, we conducted multivariable, multilevel longitudinal regression analysis using mixed effect modeling to assess whether changes in percent predicted forced expiratory volume in one second (ppFEV1), body mass index (BMI), and pulmonary exacerbations (PEx) 1-year-pre- to 1-year-post-pregnancy were associated with pregnancy planning.

RESULTS

Our analysis included 163 people with 226 pregnancies; the cohort had a mean age at conception of 29.6 years, mean pre-pregnancy ppFEV1 of 75.4 and BMI of 22.5 kg/m2. PpFEV1 declined in both PP (adjusted decline of -2.5 (95% CI: -3.8, -1.2)) and UP (adjusted decline of -3.0 (95% CI: -4.6, -1.4)) groups, they did not differ from each other (p = 0.625). We observed a difference in change in the annual number of PEx pre- to post-pregnancy (PP: 0.8 (0.7, 1.1); UP: 1.3 (1.0, 1.7); interaction effect p = 0.029). In a subset of people with available infant data, infants resulting from UP had more preterm births, lower APGAR scores, and more intensive care unit stays.

CONCLUSIONS

Following UP, there is an increased trajectory for PEx and potentially for infant complications compared to PP. Clinicians should consider increased surveillance in the setting of UP.

Causal inference in survival analysis using longitudinal observational data: Sequential trials and marginal structural models

Longitudinal observational data on patients can be used to investigate causal effects of time-varying treatments on time-to-event outcomes. Several methods have been developed for estimating such effects by controlling for the time-dependent confounding that typically occurs. The most commonly used is marginal structural models (MSM) estimated using inverse probability of treatment weights (IPTW) (MSM-IPTW). An alternative, the sequential trials approach, is increasingly popular, and involves creating a sequence of "trials" from new time origins and comparing treatment initiators and non-initiators. Individuals are censored when they deviate from their treatment assignment at the start of each "trial" (initiator or noninitiator), which is accounted for using inverse probability of censoring weights. The analysis uses data combined across trials. We show that the sequential trials approach can estimate the parameters of a particular MSM. The causal estimand that we focus on is the marginal risk difference between the sustained treatment strategies of "always treat" vs "never treat." We compare how the sequential trials approach and MSM-IPTW estimate this estimand, and discuss their assumptions and how data are used differently. The performance of the two approaches is compared in a simulation study. The sequential trials approach, which tends to involve less extreme weights than MSM-IPTW, results in greater efficiency for estimating the marginal risk difference at most follow-up times, but this can, in certain scenarios, be reversed at later time points and relies on modelling assumptions. We apply the methods to longitudinal observational data from the UK Cystic Fibrosis Registry to estimate the effect of dornase alfa on survival.

Ataluren and similar compounds (specific therapies for premature termination codon class I mutations) for cystic fibrosis

BACKGROUND

Cystic fibrosis (CF) is a common, life-shortening, genetic disorder in populations of Northern European descent caused by the mutation of a single gene that codes for the production of the cystic fibrosis transmembrane conductance regulator (CFTR) protein. This protein coordinates the transport of salt (and bicarbonate) across cell surfaces, and the mutation most notably affects the airways. In the lungs of people with CF, the defective protein compromises mucociliary clearance and makes the airway prone to chronic infection and inflammation, damaging the structure of the airways and eventually leading to respiratory failure. In addition, abnormalities in the truncated CFTR protein lead to other systemic complications, including malnutrition, diabetes and subfertility. Five classes of mutation have been described, depending on the impact of the mutation on the processing of the CFTR protein in the cell. In class I mutations, premature termination codons prevent the production of any functional protein, resulting in severe CF. Therapies targeting class I mutations aim to enable the normal cellular mechanism to read through the mutation, potentially restoring the production of the CFTR protein. This could, in turn, normalise salt transport in the cells and decrease the chronic infection and inflammation that characterises lung disease in people with CF. This is an update of a previously published review.

OBJECTIVES

To evaluate the benefits and harms of ataluren and similar compounds on clinically important outcomes in people with CF with class I mutations (premature termination codons).

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis Trials Register, which is compiled from electronic database searches and handsearching of journals and conference abstract books. We also searched the reference lists of relevant articles. The last search of the Cochrane Cystic Fibrosis Trials Register was conducted on 7 March 2022. We searched clinical trial registries maintained by the European Medicines Agency, the US National Institutes of Health and the World Health Organization. The last search of the clinical trials registries was conducted on 4 October 2022.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of parallel design comparing ataluren and similar compounds (specific therapies for class I mutations) with placebo in people with CF who have at least one class I mutation.

DATA COLLECTION AND ANALYSIS

For the included trials, the review authors independently extracted data, assessed the risk of bias and evaluated the certainty of the evidence using GRADE; trial authors were contacted for additional data.

MAIN RESULTS

Our searches identified 56 references to 20 trials; of these, 18 trials were excluded. Both the included parallel RCTs compared ataluren to placebo for 48 weeks in 517 participants (males and females; age range six to 53 years) with CF who had at least one nonsense mutation (a type of class I mutation). The certainty of evidence and risk of bias assessments for the trials were moderate overall. Random sequence generation, allocation concealment and blinding of trial personnel were well documented; participant blinding was less clear. Some participant data were excluded from the analysis in one trial that also had a high risk of bias for selective outcome reporting. PTC Therapeutics Incorporated sponsored both trials with grant support from the Cystic Fibrosis Foundation, the US Food and Drug Administration's Office of Orphan Products Development and the National Institutes of Health. The trials reported no difference between treatment groups in terms of quality of life, and no improvement in respiratory function measures. Ataluren was associated with a higher rate of episodes of renal impairment (risk ratio 12.81, 95% confidence interval 2.46 to 66.65; P = 0.002; I2 = 0%; 2 trials, 517 participants). The trials reported no treatment effect for ataluren for the review's secondary outcomes of pulmonary exacerbation, computed tomography score, weight, body mass index and sweat chloride. No deaths were reported in the trials. The earlier trial performed a post hoc subgroup analysis of participants not receiving concomitant chronic inhaled tobramycin (n = 146). This analysis demonstrated favourable results for ataluren (n = 72) for the relative change in forced expiratory volume in one second (FEV1) per cent (%) predicted and pulmonary exacerbation rate. The later trial aimed to prospectively assess the efficacy of ataluren in participants not concomitantly receiving inhaled aminoglycosides, and found no difference between ataluren and placebo in FEV1 % predicted and pulmonary exacerbation rate.  AUTHORS' CONCLUSIONS: There is currently insufficient evidence to determine the effect of ataluren as a therapy for people with CF with class I mutations. One trial reported favourable results for ataluren in a post hoc subgroup analysis of participants not receiving chronic inhaled aminoglycosides, but these were not reproduced in the later trial, suggesting that the earlier results may have occurred by chance. Future trials should carefully assess for adverse events, notably renal impairment, and consider the possibility of drug interactions. Cross-over trials should be avoided, given the potential for the treatment to change the natural history of CF.

The Changing Epidemiology of Cystic Fibrosis: The Implications for Adult Care

Cystic fibrosis (CF) is a genetic disease in which mutations in the gene encoding for the CF transmembrane conductance regulator protein result in a multisystem disease dominated by digestive and respiratory manifestations. In the mid-20th century, CF caused death within the first years of life. Over the past decades, advances in disease management, which includes systematic neonatal screening, multidisciplinary symptomatic CF care, lung transplantation and, more recently, highly effective CF transmembrane conductance regulator modulators, have transformed the prognosis of people with CF markedly. In most countries with well-established CF care, adults now outnumber children, and life expectancy is expected to increase further, narrowing the survival gap with the general population. However, marked differences in the prognosis of CF exist not only among high-, low-, and middle-income countries but also among high-income countries, based on the presence and quality of a specialized CF care provision network. Current evidence suggests that differences in patient clinical status and survival could be attributable not only to intrinsic disease severity but also to disparities in access to high-quality specialized care. Because CF is generally a progressive disease, adults with CF often show increased pulmonary severity and complications and increased occurrence of comorbidities, which highlights the need for specialized adult CF centers. This article seeks to describe the evolution of CF demography over the past decades, predict future trends, and anticipate the future provision of adult CF care.

Disparities in first evaluation of infants with cystic fibrosis since implementation of newborn screening

OBJECTIVE

We evaluated whether implementation of cystic fibrosis (CF) newborn screening (NBS) leads to equitable timeliness of initial evaluation. We compared age at first event (AFE, age at sweat test, encounter and/or care episode) between infants categorized as Black/African American, American Indian/ Native Alaskan, Asian, and/or Hispanic and/or other (Group 1) to White and not Hispanic infants (Group 2).

METHODS

This retrospective cohort study from the Cystic Fibrosis Foundation Patient Registry (CFFPR) included infants born 2010-2018. Race and ethnicity categories followed US Census definitions. The primary outcome was AFE; the secondary outcome was weight for age (WFA) z-score averaged 12 to < 24 months. We compared distributions by Wilcoxon rank-sum test and proportions by Chi-square or Fisher's exact tests. A nested cohort study used a linear mixed effects model of variables that affect WFA, chosen a priori, to evaluate associations with 1-year WFA z-score.

RESULTS

Among 6354 infants, 21% were in Group 1. Group 1 median AFE was 31 days (IQR 19, 49) and Group 2 was 22 days (IQR 14,36) (p< .001). Median WFA z-score at 1-2 years was lower in Group 1. In 3017 infants with complete data on variables of interest, AFE, Black race, CFTR variant class I-III, prematurity and public insurance were associated with lower 1-year WFA z-score.

CONCLUSIONS

Differences in AFE for infants with CF from historically marginalized groups may exacerbate long standing health disparities. We speculate that inequitable identification of CFTR gene variants and/or bias may influence timeliness of evaluation after an out-of-range NBS.

Ways of coping and survival in Cystic Fibrosis: a 20-year longitudinal study

BACKGROUND

The relationship between ways of coping and health outcomes has been a focus of interest for decades. There is increasing recognition that positive psychological functioning can influence health outcomes beneficially. This work investigated the role of coping in predicting survival in CF.

METHODS

A longitudinal observational cohort study with a 20-year follow-up period was undertaken. At entry to the study, demographic and clinical variables were recorded, and ways of coping were assessed using the Cystic Fibrosis Coping Scale which measures four distinct ways of coping: optimism, hopefulness, distraction and avoidance. Survival outcome was measured as time in days from the date of recruitment to exit from the study, where exit was either death, loss to follow-up or the end of the follow-up period.

RESULTS

Survival time was modelled using Cox's proportional hazards model. At baseline, 116 people with CF were recruited. By the census date, 54 people had died (14 men had died during 248,565 person-days of observation and 40 women had died during 358,372 person-days of observation). Optimism was the only way of coping that showed any beneficial effect on survival (RR=0.984, p=0.040) after adjustments for age, gender, ppFEV₁ and the three other coping variables measured at baseline.

CONCLUSION

This work suggests that optimistic coping serves as a prognostic measure of survival in CF beyond key clinical and demographic variables. Ways of coping are modifiable, providing a target for clinical intervention; to improve quality of life and clinical outcomes and potentially increase longevity.

Mediation of the total effect of cystic fibrosis-related diabetes on mortality: A UK Cystic Fibrosis Registry cohort study

AIM

To investigate whether the effect of cystic fibrosis-related diabetes (CFRD) on the composite outcome of mortality or transplant could act through lung function, pulmonary exacerbations and/or nutritional status.

METHODS

A retrospective cohort of adult cystic fibrosis (CF) patients who had not been diagnosed with CFRD were identified from the UK Cystic Fibrosis Registry (n = 2750). Rate of death or transplant was compared between patients who did and did not develop CFRD (with insulin use) during follow-up using Poisson regression, separately by sex. Causal mediation methods were used to investigate whether lung function, pulmonary exacerbations and nutritional status lie on the causal pathway between insulin-treated CFRD and mortality/transplant.

RESULTS

At all ages, the mortality/transplant rate was higher in both men and women diagnosed with CFRD. Pulmonary exacerbations were the strongest mediator of the effect of CFRD on mortality/transplant, with an estimated 15% [95% CI: 7%, 28%] of the effect at 2 years post-CFRD diagnosis attributed to exacerbations, growing to 24% [95% CI: 9%, 46%] at 4 years post-diagnosis. Neither lung function nor nutritional status were found to be significant mediators of this effect. Estimates were similar but with wider confidence intervals in a cohort that additionally included people with CFRD but not using insulin.

CONCLUSION

There is evidence that pulmonary exacerbations mediate the effect of CFRD on mortality but, as they are estimated to mediate less than one-quarter of the total effect, the mechanism through which CFRD influences survival may involve other factors.

The long-term effects of insulin use in incident cystic fibrosis-related diabetes: a target trial emulated using longitudinal national registry data

Introduction

Cystic fibrosis-related diabetes (CFRD) is a common complication of cystic fibrosis and is associated with deleterious clinical outcomes. Insulin is recommended as a treatment by international guidelines. However, there are scarce clinical trial data to support the use of insulin, and little is known about the long-term outcomes of treatment. The aim of this study was to compare the long-term impacts of insulin use versus non-use in CFRD.

Methods

We used data from the national UK Cystic Fibrosis Registry and adopted a target trial framework. Eligible individuals included those 12 years and older with a new diagnosis of CFRD. Outcomes were change in % predicted forced expiratory volume in 1 s (FEV₁ %) and body mass index z-scores (BMI) over a 5-year follow-up period. Treatment strategies were to receive insulin or not for the duration of follow-up. Treatment effect estimates were obtained using two methods to control for confounding: inverse-probability-of-treatment weighted estimation of marginal structural models and the G-formula.

Results

We identified 1613 individuals diagnosed with CFRD between 2008 and 2016 and included 1196 and 1192 in the FEV₁ % and BMI outcome analyses respectively. We found no evidence of an effect of insulin on FEV₁ % over the 5-year study period. Similarly, we found no overall effect of insulin on BMI; however, there was some evidence for a positive treatment effect in patients with lower baseline BMI.

Conclusion

Using well-established national registry data, we found no evidence of long-term treatment effects for insulin on FEV₁ % or BMI in people with incident CFRD.

This target trial using registry data to estimate the effects of insulin use on clinical outcomes in incident cystic fibrosis-related diabetes found no evidence of a long-term benefit (up to 5 years) of insulin use on lung function or BMIhttps://bit.ly/3B8azKz

Survival difference between high-risk and low-risk CFTR genotypes after lung transplant

BACKGROUND

While cystic fibrosis transmembrane conductance regulator (CFTR) genotypes are associated with clinical outcomes in cystic fibrosis patients, it is unknown if genotype impacts lung transplant outcomes. We sought to compare lung transplant survival and time to bronchiolitis obliterans syndrome (BOS) between high-risk, low-risk, and not yet classified CFTR genotypes.

METHODS

We used merged data from the Organ Procurement and Transplantation Network (2005-2017) and United States Cystic Fibrosis Foundation Patient Registry (2005-2016). Cox Proportional Hazards models compared graft failure after lung transplant and time to BOS among high-risk, low-risk, and not yet classified risk CFTR genotype classes.

RESULTS

Among 1,830 cystic fibrosis lung transplant recipients, median survival for those with low-risk, high-risk, and not yet classified genotype was 9.83, 6.25, and 5.75 years, respectively. Adjusted Cox models showed recipients with a low-risk genotype had 39% lower risk of death or re-transplant compared to those with high-risk genotype (adjusted HR 0.61, 95% CI = 0.40, 0.91). A subset of 1,585 lung transplant recipients were included in the BOS subgroup analysis. Adjusted analyses showed no significant difference of developing BOS among high-risk, low-risk, or not yet classified genotypes.

CONCLUSIONS

Lung transplant recipients with low-risk CFTR genotype have better survival after transplant compared to recipients with high-risk or not yet classified genotypes. Given these differences, future studies evaluating the mechanism by which CFTR genotype affects post-transplant survival could identify potential targets for intervention.

Disease severity of people with cystic fibrosis carrying residual function mutations: Data from the ECFS Patient Registry

RATIONAL

People with cystic fibrosis carrying residual function (RF) mutations are considered to have a mild disease course. This may influence caregivers and patients on how intensive the treatments should be.

OBJECTIVES

Characterize disease severity of patients carrying RF mutations, using the European CF Society Patient Registry (ECFSPR) data.

METHODS

Demographic, clinical characteristics, lung function and death probability of patients carrying at least one RF mutation were analyzed and compared to patients homozygous to minimal function mutations (MF).

MAIN RESULTS

Of the 44,594 eligible patients (median age 19.5 years, IQR 10-29.8), 6,636 (14.6%) carried RF mutations, and 37,958 (85.1%) MF mutations. Patients carrying RF mutations were older, diagnosed at a later age, had lower sweat chloride at diagnosis and better FEV1pp at each age group. However, their FEV1pp declined with age and rates of chronic Pseudomonas aeruginosa increased with age. A significant number of patients with RF had FEV1pp similar to patients with MF at each age group. 4.5% of RF patients were treated with oxygen and 2.61% had a lung transplant. With increasing age, 26.6% of RF patients were treated with pancreatic enzymes associated with a more severe lung disease. RF patients had shortened life spans, with mortality starting around the age of 20 years.

CONCLUSIONS

Patients carrying an RF mutations experience a decline of pulmonary function with age, leading to life-shortening. Standard of care therapies and augmenting CFTR function may improve their survival and quality of life.

Analysis of the genotypic profile and its relationship with the clinical manifestations in people with cystic fibrosis: study from a rare disease registry

Background

Cystic fibrosis (CF) has a vast and heterogeneous mutational spectrum in Europe. This variability has also been described in Spain, and there are numerous studies linking CFTR variants with the symptoms of the disease. Most of the studies analysed determinate clinical manifestations or specific sequence variants in patients from clinical units. Others used registry data without addressing the genotype–phenotype relationship. Therefore, the objective of this study is to describe the genetic and clinical characteristics of people with CF and to analyse the relationship between both using data from the rare disease registry of a region in southeastern Spain.

Methods

A cross-sectional study was carried out in people with a confirmed diagnosis of CF registered in the Rare Diseases Information System (SIER) of the Region of Murcia (Spain). The patients were classified into two genotypes according to the functional consequence that the genetic variants had on the CFTR protein.

Results

There were 192 people diagnosed with CF reported in the Region of Murcia as of 31 December 2018. Seventy-six genotypes and 49 different variants were described, with c.1521_1523delCTT (p. Phe508del) being the most common in 58.3% of the CF patients and 37.0% of the alleles. In addition, 67% of the patients were classified as a high-risk genotype, which was associated with a lower percentage of FEV₁ (OR: 5.3; 95% CI: 1.2, 24.4), an increased risk of colonization by Pseudomonas aeruginosa (OR: 7.5; 95% CI: 1.7, 33.0) and the presence of pancreatic insufficiency (OR: 28.1; 95% CI: 9.3, 84.4) compared to those with a low-risk genotype.

Conclusions

This is the first study in Spain that describes the mutational spectrum and its association with clinical manifestations in patients with CF using data from a rare disease registry. The results obtained allow planning for the health resources needed by people with this disease, thus contributing to the development of personalized medicine that helps to optimize health care in CF patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-022-02373-y.

Nutraceutical Approach for the Management of Cystic Fibrosis

Background:

Cystic fibrosis is an autosomal recessive monogenic disease marked by a mutation in the cystic fibrosis transmembrane conductance regulator gene. Cystic fibrosis transmembrane conductance regulator gene mutations affect respiratory, digestive and reproductive functions and impede bicarbonate, bile acid and sweat secretion. Moreover, the current trend indicates that CF is no longer only a paediatric disease; but has progressively become a disease that also affects adults. This calls to address the condition with an appropriate nutraceutical approach.

Objective:

The study aims to find and collate nutritional targets in the management of Cystic Fibrosis.

Method:

Studies highlighting the benefits of nutrients or nutraceuticals in the management of Cystic Fibrosis were included from previously published research articles (1971 to 2020). Data including nutrients, nutraceuticals, study design, study model, sample size, age, dose and duration of the dose of the supplement were extracted from the studies included and explored to understand their role.

Results:

About 26 studies are being included in the present review. It was found that nutrient interventions comprising nutraceuticals including dietary fibre, proteins and amino acids (taurine, arginine, glutathione), fats (medium-chain triglycerides, polyunsaturated fatty acids (omega-3 fatty acids)), phytochemicals (apigenin, genistein, quercetin, curcumin, allicin, beta-carotene, Pulmonaria officinalis L, Epigallocatechin-3-gallate), micronutrients including vitamin A, vitamin D, vitamin K, magnesium and zinc in addition to antioxidants exhibit improvement in the symptomatic condition of cystic fibrosis patients.

Conclusion:

The advent of nutraceuticals in the food industry and studies indicating their promising benefits have paved a path for targeted therapies in cystic fibrosis.

Inhaled Dry Powder Mannitol Treatment in Pediatric Patients with Cystic Fibrosis: Evaluation of Clinical Data in a Real-World Setting

Background: Cystic fibrosis (CF) is a genetic disorder, in which defective clearance of airway secretions leads to progressive lung function loss. Inhaled mannitol is used to increase sputum and mucociliary clearance. There are little data from real-world studies on the effectiveness of mannitol in children. Our objective was to evaluate the spirometry and clinical results of mannitol in pediatric patients. Methods: We retrospectively reviewed the records of 30 children and adolescents with CF receiving inhaled mannitol who were already on recombinant human deoxyribonuclease (rhDNase) treatment. The change in forced expiratory volume in 1 second (FEV₁) from baseline at 2-4 months was the primary outcome. Secondary measures were other spirometry results, body mass index (BMI), hospital admissions, sputum characteristics, and positive bacterial colonization. Results: Compared to baseline, we found significant improvement in percent predicted FEV₁ at 2-4 months of treatment; 84.50 (58.00-99.00) vs. 96.00 (66.00-106.00) (P = 0.0007). The absolute change in FEV₁ was +11.5% at 2-4 months, +6.5% at 5-7 months, and +4% at 8-12 months. Also, significant improvements in other spirometry results were observed. Adolescents had significantly lower FEV₁ results, but the improvement in their lung function was sustained for a more extended period than children. Mannitol provided easier sputum removal, increased sputum volume, significant decline in hospitalizations, and significantly fewer patients with positive sputum cultures. A significant increase in BMI at 8-12 months was observed. Cough was the most frequent adverse effect. Conclusion: In a real-world setting, our results demonstrated that adding mannitol to rhDNase therapy is tolerable in pediatric patients with CF and may provide improved spirometry and clinical outcomes. In addition, our results showed that mannitol provided recovery in overall lung function at 2-4 months, which was sustained up to 12 months together with improved BMI, easier sputum removal, and a decline in bacterial colonization and hospital admissions. However, cough was the most frequent side effect.

Forskolin-induced Organoid Swelling is Associated with Long-term CF Disease Progression

Rationale

Cystic fibrosis (CF) is a monogenic life-shortening disease associated with highly variable individual disease progression which is difficult to predict. Here we assessed the association of forskolin-induced swelling (FIS) of patient-derived organoids with long-term CF disease progression in multiple organs and compared FIS with the golden standard biomarker sweat chloride concentration (SCC).

Methods

We retrieved 9-year longitudinal clinical data from the Dutch CF Registry of 173 people with mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Individual CFTR function was defined by FIS, measured as the relative size increase of intestinal organoids after stimulation with 0.8 µM forskolin, quantified as area under the curve (AUC). We used linear mixed-effect models and multivariable logistic regression to estimate the association of FIS with long-term forced expiratory volume in 1 s % predicted (FEV₁pp) decline and development of pancreatic insufficiency, CF-related liver disease and diabetes. Within these models, FIS was compared with SCC.

Results

FIS was strongly associated with longitudinal changes of lung function, with an estimated difference in annual FEV₁pp decline of 0.32% (95% CI 0.11–0.54%; p=0.004) per 1000-point change in AUC. Moreover, increasing FIS levels were associated with lower odds of developing pancreatic insufficiency (adjusted OR 0.18, 95% CI 0.07–0.46; p<0.001), CF-related liver disease (adjusted OR 0.18, 95% CI 0.06–0.54; p=0.002) and diabetes (adjusted OR 0.34, 95% CI 0.12–0.97; p=0.044). These associations were absent for SCC.

Conclusion

This study exemplifies the prognostic value of a patient-derived organoid-based biomarker within a clinical setting, which is especially important for people carrying rare CFTR mutations with unclear clinical consequences.

Forskolin-induced swelling of patient-derived intestinal organoids is associated with long-term cystic fibrosis disease progression, expressed as FEV₁pp decline and development of pancreatic insufficiency, CF-related liver disease and CF-related diabeteshttps://bit.ly/3tjjJzU

Geographic distribution and phenotype of European people with cystic fibrosis carrying A1006E mutation

BACKGROUND

A1006E is a Cystic Fibrosis (CF) mutation that is still not widely known. We report phenotypic features and geographic distribution of the largest cohort of people with CF (pwCF) carrying A1006E to date.

METHODS

Study of European pwCF carrying A1006E mutation, included in the European CF Society Patient Registry (ECFSPR). Genotype, ancestries and all variables recorded were compared to a cohort of F508del/F508del patients. Rate of decline in percentage-of-predicted FEV₁ (ppFEV₁) was also analyzed using the 2010-2017 ECFSPR.

RESULTS

44 pwCF carrying A1006E were reported (59% males), median age 33 years old (3-58), 54.5% Spanish and 40.9% Italian, most with ancestry in Murcia (Spain) and Lazio (Italy) regions. Compared to F508del homozygous, A1006E-pwCF were significantly older (75% vs. 52.5% ≥ 18 years old) and diagnosed at later median age (6.98 vs. 0.29 years); showed lower rates of meconium ileus (2.33% vs. 17.7%), pancreatic insufficiency (27.91% vs. 99.26%), diabetes (2.33% vs. 21.98%), liver disease (6.98% vs. 36.72%) and Pseudomonas aeruginosa chronic colonization (30.95% vs. 42.51%); and presented better nutrition (BMI z-score 0.44 vs. -0.43) and ppFEV₁ (90.8% vs. 78.6%), with 18.9% (most >40 years old) having a ppFEV₁<70%. Additional ppFEV₁ decline (0.96% per year) was attributed to F508del/F508del genotype (p = 0.0007). None died or needed organ transplantation during the study period.

CONCLUSIONS

A1006E-pwCF are mainly of Western Mediterranean Spanish and Italian descent. When compared with F508del/F508del-pwCF, they usually have a milder form of the disease, associated with pancreatic sufficiency and slower FEV₁ decline. However, some will develop progressive respiratory impairment during adulthood.

Burden of cystic fibrosis in children <12 years of age prior to the introduction of CFTR modulator therapies

Background

Cystic fibrosis (CF) is a genetic, multisystemic, progressive and life-shortening disease caused by mutations in the CF transmembrane conductance regulator (CFTR) gene. Different genotypes have been linked to variations in disease progression among people with CF. The burden of illness (BOI) in children with CF is incompletely characterised, particularly as it relates to CFTR genotypes prior to the availability of the first CFTR modulators. This retrospective, cross-sectional, descriptive study evaluated the BOI in US children with CF <12 years of age prior to the first approval of CFTR modulators.

Methods

Data from the US Cystic Fibrosis Foundation Patient Registry from 2011 were used to summarise key patient and disease characteristics using descriptive statistics, overall and grouped by age (0 to <2 years, 2 to <6 years and 6 to <12 years) and genotype (F508del/F508del, F508del/minimal function (MF), MF/MF, gating mutation on ≥1 allele, residual function mutation on ≥1 allele and R117H on ≥1 allele) group.

Results

The analysis included 9185 children. Among 6-year-olds to <12-year-olds, mean (SD) per cent predicted FEV₁ in 1 s was 92.6% (17.5%). Among all children <12 years of age, the mean (SD) all-cause hospitalisation and pulmonary exacerbation rates in 2011 were 0.4 (1.0) and 0.3 (0.8), respectively. Most (93.6%) had ≥1 positive lung microbiology culture. CF-related medication and nutritional supplementation use was common across all ages and genotypes. More than half (54.7%) had ≥1 CF-related complication. Evidence of disease burden was observed across the age and genotype groups studied.

Conclusions

Prior to the approval of the first CFTR modulator therapies in children <12 years of age, CF was associated with substantial BOI from an early age—including respiratory infections, hospitalisations/pulmonary exacerbations, need for supplemental nutrition and pharmacological treatments—irrespective of genotype.

A retrospective study of cases diagnosed with cystic fibrosis at a single care center in Syria

Background

Although there is relatively much information about the status of cystic fibrosis disease in different countries of the world, limited data are available on this disease among Syrian children. Therefore, we did a retrospective study that included 173 children diagnosed with cystic fibrosis according to the diagnostic criteria. This study was conducted to determine the diagnostic, clinical, and genetic characteristics of patients with cystic fibrosis in Syria and to assess the relationship between the genotype and the phenotype of disease in these patients.

Results

As a result of the early classical manifestations, CF diagnosis was established in the present study by the age of 1 year in 78.6%; the mortality rate was 23.1% (82.5% of them were in the first year of life). The prevalence of respiratory and gastrointestinal symptoms was 81.5% and 78.6%, respectively with an average age of 7.8 and 3.4 months. Consanguinity was reported in 75.7% of the families. The most common pathogenic variant in the sample was F508del (36%) followed by W1282X (17%). There was a statistical correlation between incidence of steatorrhea and the presence of class I pathogenic variants. A relationship between the mortality rate and the presence of class II pathogenic variants (pathogenic deletion variants) was also observed. There was no statistical relationship between other clinical manifestation and pathogenic variant classes. However, the incidence of most CF-related conditions was a little higher in the presence of classes I, II, and III pathogenic variants compared to their incidence in the presence of classes IV and V pathogenic variants.

Conclusions

The number of cases diagnosed with cystic fibrosis in Syria is less than the number of real cases, and there is a need to perform CFTR gene sequencing on large sample sizes, to determine all CFTR pathogenic variants that could exist in Syrian patients and to make a better evaluation of the relationship between genotype and phenotype of the disease.

Prevalence, variability, and predictors of sinus surgery in pediatric patients with cystic fibrosis

INTRODUCTION

Chronic rhinosinusitis is common among individuals with cystic fibrosis (CF) and has an impact on quality of life. Sinus surgery is a treatment option, but minimal literature exists regarding prevalence and indications.

METHODS

Using the linked CF Foundation Patient Registry (CFFPR) - Pediatric Health Information Systems (PHIS) database, we investigated variability in receipt of surgery, predictors of surgery, and time to first surgery. We included individuals less than 18 receiving care between 2006 and 2015 at a CF Foundation care program that is also a PHIS-participating-hospital. We used logistic regression to examine predictors of receipt of surgery and a Kaplan-Meier curve to examine time to first surgery among those born 2005-2007.

RESULTS

There were 11,545 children and adolescents and 2156 (18.7%) received at least one surgery. Variation in number of surgeries was observed across hospitals (median: 63 [IQR, 33-110]). There was an inconsistent pattern between receipt of surgery and markers of disease severity; those receiving surgery having increased odds of treatment use and pulmonary exacerbations and decreased odds of lower lung function and body mass index. Among the cohort of young children, 159 (14%) had at least one surgery with a median age at first surgery of 5.6 (IQR, 3.9-7.0).

CONCLUSIONS

The use of sinus surgery is frequent, but variable, among children and adolescents. Clinical factors are associated with receipt of surgery, but further understanding is needed on other factors that impact variability in use. Our study indicates the need for additional evaluation of the management of CF-related CRS and indications for surgery.

The determinants of survival among adults with cystic fibrosis-a cohort study

BACKGROUND

Cystic fibrosis (CF) is one of the most common autosomal recessive diseases. Factors contributing to disease exacerbations and survival rate of CF patients are type of mutation in the CFTR gene, poor nutritional status, lung failure, and infection development by Pseudomonas aeruginosa. The study aimed to evaluate the relationship between the severity of mutation, nutritional status, lung function, and Pseudomonas aeruginosa prevalence and survival rate in adult patients with cystic fibrosis.

METHODS

A study of 124 (68 ♀ and 56 ♂) adults with CF aged 18-51 years were evaluated for (a) type of mutation in the CFTR gene, (b) nutritional status (BMI), (c) lung function (FEV₁%), and (d) Pseudomonas aeruginosa prevalence. For statistical calculations, Kaplan-Meier analysis of survival, chi-squared test for multiple samples, and logistic regression were used.

RESULTS

The type of mutation (χ² = 12.73, df = 3, p = 0.005), FEV₁% (χ² = 15.20, df = 2, p = 0.0005), Pseudomonas aeruginosa prevalence (χ² = 11.48, df = 3, p = 0.009), and BMI (χ² = 31.08, df = 4, p < 0.000) significantly differentiated the probability of survival of patients with CF. The shortest life expectancy was observed in patients with a severe type of mutation on both alleles, FEV₁% < 40, subjects in whom Pseudomonas culture was extensively drug-resistant or pandrug-resistant, and patients whose BMI was lower than 18.5 kg/m². The period from 30 to 40 years of age was the most critical in CF adults' lifespan. The risk of adults with CF death doubled with Pseudomonas aeruginosa prevalence (OR = 2.06, 95% CI 1.29; 2.28) and eightfold when the bacteria acquired antibiotic resistance (OR = 8.11, 95% CI 1.67; 38.15).

CONCLUSIONS

All factors included in the study were significantly related to the survival rate of patients with cystic fibrosis.

Cystic fibrosis transmembrane conductance regulator modulators for cystic fibrosis: a new dawn?

Cystic fibrosis (CF) is the most common life-limiting inherited condition in Caucasians. It is a multisystem autosomal recessive disorder caused by variants in the gene for cystic fibrosis transmembrane conductance regulator (CFTR) protein, a cell-surface localised chloride channel that regulates absorption and secretion of salt and water across epithelia. Until recently, the treatment for CF was predicated on ameliorating and preventing the downstream symptoms of CFTR dysfunction, primarily recurrent respiratory infections and pancreatic exocrine failure. But a new class of therapy-the CFTR modulators, which treat the basic defect and decrease the complications of CF, leads to significantly improved pulmonary function, decreased respiratory infections and improved nutrition. The newest agent, a combination of elexacaftor, tezacaftor and ivacaftor, will be suitable for approximately 90% of all people with CF and is likely to decrease the morbidity and significantly increase the life expectancy for most people with CF. The major barrier to their widespread introduction has been their cost, with many countries unwilling or unable to fund them. Nevertheless, such is their therapeutic efficacy and their likely potent effect on life expectancy that their advent has wider societal implications for the care of children and adults with CF.

Disease burden in people with cystic fibrosis heterozygous for F508del and a minimal function mutation

BACKGROUND

People with cystic fibrosis (CF) heterozygous for F508del-CFTR and a minimal function CFTR mutation (F/MF) that results in no CFTR protein or results in CFTR protein that is not responsive to tezacaftor, ivacaftor, and tezacaftor/ivacaftor in vitro comprise a sizeable percentage of the US CF population. This retrospective, cross-sectional, observational study aimed to characterize CF burden in this subpopulation.

METHODS

People ≥2 years of age in the US CF Foundation Patient Registry with a CF diagnosis, F/MF genotype, and ≥1 encounters in 2017 were included. Descriptive analyses assessed lung function, nutritional parameters, microbiology, hospitalization and pulmonary exacerbation rates, and CF-related complications. Results were stratified by age group; select characteristics were summarized by percent predicted FEV₁ (ppFEV₁) and ethnicity.

RESULTS

5348 people met inclusion criteria. Rates of positive bacterial cultures, pulmonary exacerbations, and hospitalizations were generally higher in older age groups. Prevalence of prescribed symptomatic CF therapies was substantial and also generally higher in older age groups. ppFEV₁ was lower in older age groups. A greater percentage of adolescents and adults reported complications, including cirrhosis, osteoporosis, osteopenia, and sinus disease, than younger age groups. Increased prevalence of cultured Pseudomonas aeruginosa and prescribed chronic therapy was seen with decreasing ppFEV₁. In each age group, ppFEV₁ was slightly higher in the non-Hispanic cohort than in the Hispanic cohort.

CONCLUSIONS

People with F/MF genotypes have substantial disease burden that worsened in older age groups consistent with the progressive nature of CF, indicating need for additional treatment options in this subpopulation.

Tensin 1 (TNS1) is a modifier gene for low body mass index (BMI) in homozygous [F508del]CFTR patients

Cystic fibrosis (CF) is a life‐limiting autosomal recessive genetic disease caused by variants in the CFTR gene, most commonly by the [F508del] variant. Although CF is a classical Mendelian disease, genetic variants in several modifier genes have been associated with variation of the clinical phenotype for pulmonary and gastrointestinal function and urogenital development. We hypothesized that whole genome sequencing of a well‐phenotyped CF populations might identify novel variants in known, or hitherto unknown, modifier genes. Whole genome sequencing was performed on the Illumina HiSeq X platform for 98 clinically diagnosed cystic fibrosis patient samples from the Adult CF Clinic at the University of California San Diego (UCSD). We compared protein‐coding, non‐silent variants genome wide between CFTR [F508del] homozygotes vs CFTR compound heterozygotes. Based on a single variant score test, we found 3 SNPs in common variants (MAF >5%) that occurred at significantly different rates between homozygous [F508del]CFTR and compound heterozygous [F508del]CFTR patients. The 3 SNPs were all located in one gene on chromosome 2: Tensin 1 (TNS1: rs3796028; rs2571445: and rs918949). We observed significantly lower BMIs in homozygous [F508del]CFTR patients who were also homozygous for Tensin 1 rs918949 (T/T) (p = 0.023) or rs2571445 (G/G) (p = 0.02) variants. The Tensin 1 gene is thus a potential modifier gene for low BMI in CF patients homozygous for the [F508del]CFTR variant.

Cystic fibrosis patients of minority race and ethnicity less likely eligible for CFTR modulators based on CFTR genotype

BACKGROUND

Cystic fibrosis transmembrane conductance regulator (CFTR) modulators are disease-modifying medications for cystic fibrosis (CF) and are shown to be efficacious for only specific CFTR mutations. CFTR mutation frequency varies by ancestry, which is different from but related to demographic racial and ethnic group. Eligibility for CFTR modulator therapy has not been previously reported by race and ethnicity.

METHODS

We conducted a cross-sectional study of patients in the 2018 CF Foundation Patient Registry. We analyzed the percentage of patients in each US Census defined racial and ethnic group eligible for CFTR modulators based on CFTR mutations approved by the US FDA and then based on both mutations and FDA approval by age. We compared lung function based on CFTR modulator eligibility and prescription.

FINDINGS

Based on CFTR mutations alone, 92.4% of non-Hispanic White patients, 69.7% of Black/African American patients, 75.6% of Hispanic patients, and 80.5% of other race patients eligible for CFTR modulators. For each CFTR modulator, Black/African American patients were least likely to have eligible mutations, and non-Hispanic White patients were most likely. There was no difference in the disparity between racial and/or ethnic groups with the addition of current FDA approval by age. The lowest pulmonary function in the cohort was seen in non-Hispanic White, Black/African American, and Hispanic patients not eligible for CFTR modulators.

INTERPRETATION

Patients with CF from minority groups are less likely to be eligible for CFTR modulators. Because people with CF who are racial and ethnic minorities have increased disease severity and earlier mortality, this will further contribute to health disparities.

Quantification of Phenotypic Variability of Lung Disease in Children with Cystic Fibrosis

Cystic fibrosis (CF) lung disease has the greatest impact on the morbidity and mortality of patients suffering from this autosomal-recessive multiorgan disorder. Although CF is a monogenic disorder, considerable phenotypic variability of lung disease is observed in patients with CF, even in those carrying the same mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene or CFTR mutations with comparable functional consequences. In most patients with CF, lung disease progresses from childhood to adulthood, but is already present in infants soon after birth. In addition to the CFTR genotype, the variability of early CF lung disease can be influenced by several factors, including modifier genes, age at diagnosis (following newborn screening vs. clinical symptoms) and environmental factors. The early onset of CF lung disease requires sensitive, noninvasive measures to detect and monitor changes in lung structure and function. In this context, we review recent progress with using multiple-breath washout (MBW) and lung magnetic resonance imaging (MRI) to detect and quantify CF lung disease from infancy to adulthood. Further, we discuss emerging data on the impact of variability of lung disease severity in the first years of life on long-term outcomes and the potential use of this information to improve personalized medicine for patients with CF.

DeltaF508 CFTR Hetero- and Homozygous Paediatric Patients with Cystic Fibrosis Do Not Differ with Regard to Nutritional Status

The purpose of this study was to compare the nutritional status between deltaF508 CFTR hetero- and homozygous paediatric patients with cystic fibrosis. We assessed the percentage profiles of fatty acids measured in erythrocyte membranes and the serum levels of vitamins A, D3, E and K1 in the studied groups. We also measured the weights and heights and calculated the body mass indexes (BMIs). The studied groups consisted of 34 heterozygous and 30 homozygous patients. No statistically significant differences were found in the serum vitamins or erythrocyte membrane fatty acid profiles between the hetero- and homozygous patient groups, except for heptadecanoic acid (p = 0.038). The mean percentiles of height, weight and BMI did not differ significantly between the two groups. The homozygous and heterozygous paediatric patients with cystic fibrosis were similar in terms of their nutritional statuses.

Inflammasome Genetic Variants, Macrophage Function, and Clinical Outcomes in Cystic Fibrosis

Cystic fibrosis (CF) is characterized by chronic airway infection, inflammation, and tissue damage that lead to progressive respiratory failure. NLRP3 and NLRC4 are cytoplasmic pattern recognition receptors that activate the inflammasome, initiating a caspase-1-mediated response. We hypothesized that gain-of-function inflammasome responses are associated with worse outcomes in children with CF. We genotyped nonsynonymous variants in NLRP3 and the NLRC4 pathway from individuals in the EPIC (Early Pseudomonas Infection Control) Observational Study cohort and tested for association with CF outcomes. We generated knockouts of NLRP3 and NLRC4 in human macrophage-like cells and rescued knockouts with wild-type or variant forms of NLRP3 and NLRC4. We identified a SNP in NLRP3, p.(Q705K), that was associated with a higher rate of P. aeruginosa colonization (N = 609; P = 0.01; hazard ratio, 2.3 [Cox model]) and worsened lung function over time as measured by forced expiratory volume in 1 second (N = 445; P = 0.001 [generalized estimating equation]). We identified a SNP in NLRC4, p.(A929S), that was associated with a lower rate of P. aeruginosa colonization as part of a composite of rare variants (N = 405; P = 0.045; hazard ratio, 0.68 [Cox model]) and that was individually associated with protection from lung function decline (P < 0.001 [generalized estimating equation]). Rescue of the NLRP3 knockout with the p.(Q705K) variant produced significantly more IL-1β in response to NLRP3 stimulation than rescue with the wild type (P = 0.020 [Student's t test]). We identified a subset of children with CF at higher risk of early lung disease progression. Knowledge of these genetic modifiers could guide therapies targeting inflammasome pathways.

Survival estimates in European cystic fibrosis patients and the impact of socioeconomic factors: a retrospective registry cohort study

BACKGROUND

Median survival for cystic fibrosis (CF) patients in Europe is unknown and is likely to be influenced by socioeconomic factors. Using the European CF Society Patient Registry (ECFSPR), median survival estimates were obtained for CF patients across Europe and the impact of socioeconomic status on survival was examined.

METHODS

CF subjects known to be alive and in the ECFSPR between 2010 and 2014 were included. Survival curves were estimated using the Kaplan-Meier method. Differences in the survival curves were assessed using the log-rank test. Cox regression was used to estimate the association between socioeconomic factors and the age-specific hazard of death, with adjustment for sex, age at diagnosis, CF transmembrane conductance regulator (CFTR) genotype and transplant status.

RESULTS

The final analysis included 13 countries with 31 987 subjects (135 833 person-years of follow-up) and 1435 deaths. Median survival age for these patients in the ECFSPR was 51.7 (95% CI 50.0-53.4) years. After adjusting for potential confounders age at diagnosis, sex, CFTR genotype and transplant status, there remained strong evidence of an association between socioeconomic factors and mortality (p<0.001). Countries in the highest third of healthcare spending had a 46% lower hazard of mortality (HR 0.54, 95% CI 0.45-0.64) than countries in the lowest third of healthcare spending.

CONCLUSIONS

Median survival for patients with CF in Europe is comparable to that reported in other jurisdictions and differs by socioeconomic factors.

Long-term safety and efficacy of tezacaftor-ivacaftor in individuals with cystic fibrosis aged 12 years or older who are homozygous or heterozygous for Phe508del CFTR (EXTEND): an open-label extension study

BACKGROUND

Tezacaftor-ivacaftor is an approved cystic fibrosis transmembrane conductance regulator (CFTR) modulator shown to be efficacious and generally safe and well tolerated over 8-24 weeks in phase 3 clinical studies in participants aged 12 years or older with cystic fibrosis homozygous for the Phe508del CFTR mutation (F/F; study 661-106 [EVOLVE]) or heterozygous for the Phe508del CFTR mutation and a residual function mutation (F/RF; study 661-108 [EXPAND]). Longer-term (>24 weeks) safety and efficacy of tezacaftor-ivacaftor has not been assessed in clinical studies. Here, we present results of study 661-110 (EXTEND), a 96-week open-label extension study that assessed long-term safety, tolerability, and efficacy of tezacaftor-ivacaftor in participants aged 12 years or older with cystic fibrosis who were homozygous or heterozygous for the Phe508del CFTR mutation.

METHODS

Study 661-110 was a 96-week, phase 3, multicentre, open-label study at 170 clinical research sites in Australia, Europe, Israel, and North America. Participants were aged 12 years or older, had cystic fibrosis, were homozygous or heterozygous for Phe508del CFTR, and completed one of six parent studies of tezacaftor-ivacaftor: studies 661-103, 661-106, 661-107, 661-108, 661-109, and 661-111. Participants received oral tezacaftor 100 mg once daily and oral ivacaftor 150 mg once every 12 h for up to 96 weeks. The primary endpoint was safety and tolerability. Secondary endpoints were changes in lung function, nutritional parameters, and respiratory symptom scores; pulmonary exacerbations; and pharmacokinetic parameters. A post-hoc analysis assessed the rate of lung function decline in F/F participants who received up to 120 weeks of tezacaftor-ivacaftor in studies 661-106 (F/F) and/or 661-110 compared with a matched cohort of CFTR modulator-untreated historical F/F controls from the Cystic Fibrosis Foundation Patient Registry. Primary safety analyses were done in all participants from all six parent studies who received at least one dose of study drug during this study. This study was registered at ClinicalTrials.gov (NCT02565914).

FINDINGS

Between Aug 31, 2015, to May 31, 2019, 1044 participants were enrolled in study 661-110 from the six parent studies of whom 1042 participants received at least one dose of study drug and were included in the safety set. 995 (95%) participants had at least one TEAE; 22 (2%) had TEAEs leading to discontinuation; and 351 (34%) had serious TEAEs. No deaths occurred during the treatment-emergent period; after the treatment-emergent period, two deaths occurred, which were both deemed unrelated to study drug. F/F (106/110; n=459) and F/RF (108/110; n=226) participants beginning tezacaftor-ivacaftor in study 661-110 had improvements in efficacy endpoints consistent with parent studies; improvements in lung function and nutritional parameters and reductions in pulmonary exacerbations observed in the tezacaftor-ivacaftor groups in the parent studies were generally maintained in study 661-110 for an additional 96 weeks. Pharmacokinetic parameters were also similar to those in the parent studies. The annualised rate of lung function decline was 61·5% (95% CI 35·8 to 86·1) lower in tezacaftor-ivacaftor-treated F/F participants versus untreated matched historical controls.

INTERPRETATION

Tezacaftor-ivacaftor was generally safe, well tolerated, and efficacious for up to 120 weeks, and the safety profile of tezacaftor-ivacaftor in study 661-110 was consistent with cystic fibrosis manifestations and with the safety profiles of the parent studies. The rate of lung function decline was significantly reduced in F/F participants, consistent with cystic fibrosis disease modification. Our results support the clinical benefit of long-term tezacaftor-ivacaftor treatment for people aged 12 years or older with cystic fibrosis with F/F or F/RF genotypes.

FUNDING

Vertex Pharmaceuticals Incorporated.

Impact of a Gap Junction Protein Alpha 4 Variant on Clinical Disease Phenotype in F508del Homozygous Patients With Cystic Fibrosis

Background

Lung disease phenotype varies widely even in the F508del (homozygous) genotype. Leukocyte-driven inflammation is important for pulmonary disease pathogenesis in cystic fibrosis (CF). Blood cytokines correlate negatively with pulmonary function in F508del homozygous patients, and gap junction proteins (GJA) might be related to the influx of blood cells into the lung and influence disease course. We aimed to assess the relationship between GJA1/GJA4 genotypes and the clinical disease phenotype.

Methods

One-hundred-and-sixteen homozygous F508del patients (mean age 27 years, m/f 66/50) were recruited from the CF centers of Bonn, Frankfurt, and Amsterdam. Sequence analysis was performed for GJA1 and GJA4. The clinical disease course was assessed over 3 years using pulmonary function tests, body mass index, Pseudomonas aeruginosa colonization, diabetes mellitus, survival to end-stage lung disease, blood and sputum inflammatory markers.

Results

Sequence analysis revealed one clinically relevant single nucleotide polymorphism. In this GJA4 variant (rs41266431), homozygous G variant carriers (n = 84/116; 72.4%) had poorer pulmonary function (FVC% pred: mean 78/86, p < 0.040) and survival to end-stage lung disease was lower (p < 0.029). The frequency of P. aeruginosa colonization was not influenced by the genotype, but in those chronically colonized, those with the G/G genotype had reduced pulmonary function (FVC% pred: mean 67/80, p < 0.049). Serum interleukin-8 (median: 12.4/6.7 pg/ml, p < 0.052) and sputum leukocytes (2305/437.5 pg/ml, p < 0.025) were higher for the G/G genotype.

Conclusions

In carriers of the A allele (27.6%) the GJA4 variant is associated with significantly better protection against end-stage lung disease and superior pulmonary function test results in F508del homozygous patients. This SNP has the potential of a modifier gene for phenotyping severity of CF lung disease, in addition to the CFTR genotype.

Clinical Trial Registration

The study was registered with ClinicalTrials.gov, number NCT04242420, retrospectively on January 24th, 2020.

Ivacaftor Is Associated with Reduced Lung Infection by Key Cystic Fibrosis Pathogens. A Cohort Study Using National Registry Data

Rationale: Ivacaftor can greatly improve clinical outcomes in people with cystic fibrosis (CF) and has been shown to have in vitro antibacterial properties, yet the long-term microbiological outcomes of treatment are unknown.Objectives: To investigate changes in respiratory microbiology associated with long-term ivacaftor use.Methods: This was a retrospective cohort study using data from the UK CF Registry 2011-2016. Primary outcome was the annual prevalence ratios for key CF pathogens between ivacaftor users and their contemporaneous comparators. Multivariable log-binomial regression models were designed to adjust for confounders. Changes in Pseudomonas aeruginosa status were compared between groups using nonparametric maximum likelihood estimate for the purposes of Kaplan-Meier approximation.Results: Ivacaftor use was associated with early and sustained reduction in P. aeruginosa rates (2016 adjusted prevalence ratio, 0.68; 95% confidence interval, 0.58-0.79; P < 0.001) via a combination of increased clearance in those with infection (ivacaftor: 33/87 [37.9%] vs. nonivacaftor: 432/1,872 [22.8%]; P < 0.001) and reduced acquisition in those without infection (49/134 [36.6%] vs. 1,157/2,382 [48.6%]; P = 0.01). The improved prevalence of P. aeruginosa infection was independent of reduced sampling in the ivacaftor cohort. Ivacaftor was also associated with reduced prevalence of Staphylococcus aureus and Aspergillus spp. but not Burkholderia cepacia complex.Conclusions: In this study, long-term ivacaftor use was associated with reduced infection with important CF pathogens including P. aeruginosa. These findings have implications for antibiotic stewardship and the need for ongoing chronic antimicrobial therapy in this cohort.

Efficacy and safety of ataluren in patients with nonsense-mutation cystic fibrosis not receiving chronic inhaled aminoglycosides: The international, randomized, double-blind, placebo-controlled Ataluren Confirmatory Trial in Cystic Fibrosis (ACT CF)

BACKGROUND

Ataluren was developed for potential treatment of nonsense-mutation cystic fibrosis (CF). A previous phase 3 ataluren study failed to meet its primary efficacy endpoint, but post-hoc analyses suggested that aminoglycosides may have interfered with ataluren's action. Thus, this subsequent trial (NCT02139306) was designed to assess the efficacy and safety of ataluren in patients with nonsense-mutation CF not receiving aminoglycosides.

METHODS

Eligible subjects with nonsense-mutation CF (aged ≥6 years; percent predicted (pp) FEV1 ≥40 and ≤90) from 75 sites in 16 countries were randomly assigned in double-blinded fashion to receive oral ataluren or matching placebo thrice daily for 48 weeks. The primary endpoint was absolute change in average ppFEV1 from baseline to the average of Weeks 40 and 48.

FINDINGS

279 subjects were enrolled; 138 subjects in the ataluren arm and 136 in the placebo arm were evaluable for efficacy. Absolute ppFEV1 change from baseline did not differ significantly between the ataluren and placebo groups at Week 40 (-0.8 vs -1.8) or Week 48 (-1.7 vs -2.4). Average ppFEV1 treatment difference from baseline to Weeks 40 and 48 was 0.6 (95% CI -1.3, 2.5; p = 0.54). Pulmonary exacerbation rate per 48 weeks was not significantly different (ataluren 0.95 vs placebo 1.13; rate ratio p = 0.40). Safety was similar between groups. No life-threatening adverse events or deaths were reported.

INTERPRETATION

Neither ppFEV1 change nor pulmonary exacerbation rate over 48 weeks were statistically different between ataluren and placebo groups. Development of a nonsense-mutation CF therapy remains elusive.

Longitudinal Trends in Real-World Outcomes after Initiation of Ivacaftor. A Cohort Study from the Cystic Fibrosis Registry of Ireland

RATIONALE

Patient registries have the potential to collect and analyze high-quality postauthorization data on new medicines.

OBJECTIVES

We used cystic fibrosis (CF) registry data to assess outcomes after the initiation of ivacaftor, a CF transmembrane conductance regulator (CFTR) potentiator approved for the treatment of CF with a defective gating CFTR mutation.

METHODS

Longitudinal trends were examined using mixed-effects regression analysis in 80 ivacaftor-treated patients with CF aged 6 to 56 years registered with the CF Registry of Ireland with at least 36 months of before and after commencement data. The effects of ivacaftor treatment on forced expiratory volume in 1 second (FEV₁) % predicted, body mass index (BMI), hospitalization for pulmonary exacerbation, and oral and intravenous antibiotic use were assessed.

RESULTS

In the 36 months after ivacaftor initiation, FEV₁% predicted improved by 2.26% per annum (95% confidence interval [CI], 0.2 to 4.3) for patients aged younger than 12 years, remained unchanged for 12- to younger than 18-year-olds (95% CI, -1.9 to 2.9), and declined in adults by 1.74% per annum (95% CI, -3.1 to -0.4). BMI in adults increased 0.28 kg/m² per annum (95% CI, 0.03 to 0.5), and there was no significant change in BMI z-score in children (95% CI, -0.01 to 0.1). In the year after ivacaftor initiation, intravenous antibiotic treatment reduced by 46% (95% CI, -62.5% to -23.3%, oral antibiotic treatment reduced by 49% (95% CI, -61.1% to -32.1%), and there was no significant reduction in hospitalization (95% CI, -59.2% to 9.7%).

CONCLUSIONS

In this study of real-world CF registry data, clinical outcomes improved and healthcare resource utilization decreased after commencing ivacaftor.

TAS2R38 is a novel modifier gene in patients with cystic fibrosis

The clinical manifestation of cystic fibrosis (CF) is heterogeneous also in patients with the same cystic fibrosis transmembrane regulator (CFTR) genotype and in affected sibling pairs. Other genes, inherited independently of CFTR, may modulate the clinical manifestation and complications of patients with CF, including the severity of chronic sinonasal disease and the occurrence of chronic Pseudomonas aeruginosa colonization. The T2R38 gene encodes a taste receptor and recently its functionality was related to the occurrence of sinonasal diseases and upper respiratory infections. We assessed the T2R38 genotype in 210 patients with CF and in 95 controls, relating the genotype to the severity of sinonasal disease and to the occurrence of P. aeruginosa pulmonary colonization. The frequency of the PAV allele i.e., the allele associated with the high functionality of the T2R38 protein, was significantly lower in i) CF patients with nasal polyposis requiring surgery, especially in patients who developed the complication before 14 years of age; and ii) in CF patients with chronic pulmonary colonization by P. aeruginosa, especially in patients who were colonized before 14 years of age, than in control subjects. These data suggest a role for T2R38 as a novel modifier gene of sinonasal disease severity and of pulmonary P. aeruginosa colonization in patients with CF.

Influence of sex gap on muscle strength and functional mobility in patients with cystic fibrosis

The objectives of this study were to determine whether there were differences in handgrip strength and functional mobility between patients with cystic fibrosis (CF) and healthy controls with regard to sex and to ascertain whether these differences were related to lung function. Thirty-eight patients with CF (21 women) and 38 healthy controls aged 18–65 years were included. Muscle weakness and functional mobility were assessed through handgrip strength; walking speed; and time, velocity, and power derived from a single sit-to-stand (STS) test. Patients with CF showed differences for STS variables and walking speed but not for handgrip strength, compared with healthy controls. Considering sex differences, female patients showed differences for all variables analyzed while males with CF only exhibited differences for STS variables, compared with healthy controls. Females with CF showed moderate relationship between muscle weakness, functional mobility, and lung function (|r| = 0.45–0.49; p ≤ 0.05) whereas no relationships were observed for males with CF. The influence of chronic infection with Pseudomonas aeruginosa and pancreatic insufficiency on muscle weakness and functional mobility was similar in both sexes. Differences in muscle strength and functional mobility were predominantly observed in females with CF. These results suggest an important effect of sex gap on muscle weakness and functional mobility in patients with CF.

Novelty The influence of sex gap on muscle weakness in CF has been shown. Muscle weakness was predominantly observed in females with CF.

Cystic Fibrosis Transmembrane Conductance Regulator Modulator Therapy: A Review for the Otolaryngologist

Background

Cystic fibrosis (CF) is a genetic disease that may result in multiple systemic disorders and potentially fatal severe respiratory compromise. However, the advent of CF transmembrane conductance regulator (CFTR) modulators has changed the management of CF for patients with select mutations. Although clinical trials have highlighted increased pulmonary function and decreased exacerbations as a result of these novel therapies, their effect on the sinuses has not been well-described.

Objective

Our objective is to review the CFTR modulators to provide otolaryngologists, physicians who frequently care for patients with CF, a basic understanding of these drugs and their effects on chronic rhinosinusitis (CRS) in patients with CF.

Methods

The clinically approved and available CFTR modulators and specific indications for their use are reviewed. Additionally, a systematic review of these therapies and effects on CRS in CF was performed.

Results

Four Food and Drug Administration approved CFTR modulators are available for patients with CF. Current drugs are approved for gating, residual function, or F508del mutations. Multiple reports describe CFTR modulators’ increase in transepithelial ion transport in nasal epithelial cultures; however, clinical studies regarding effects of these modulators on sinonasal health are limited to 5 studies that present new data of the effects of CFTR modulators in CRS.

Conclusions

CFTR modulators have changed management of CF. Initial studies of these medications demonstrate promising results in CF; however, there is a paucity of literature describing the effect of CFTR modulators on CF-associated CRS, although initial results are encouraging.

Correlating Cystic Fibrosis Transmembrane Conductance Regulator Function with Clinical Features to Inform Precision Treatment of Cystic Fibrosis

Rationale: The advent of precision treatment for cystic fibrosis using small-molecule therapeutics has created a need to estimate potential clinical improvements attributable to increases in cystic fibrosis transmembrane conductance regulator (CFTR) function. Objectives: To derive CFTR function of a variety of CFTR genotypes and correlate with key clinical features (sweat chloride concentration, pancreatic exocrine status, and lung function) to develop benchmarks for assessing response to CFTR modulators. Methods: CFTR function assigned to 226 unique CFTR genotypes was correlated with the clinical data of 54,671 individuals enrolled in the Clinical and Functional Translation of CFTR (CFTR2) project. Cross-sectional FEV₁% predicted measurements were plotted by age at which measurement was obtained. Shifts in sweat chloride concentration and lung function reported in CFTR modulator trials were compared with function-phenotype correlations to assess potential efficacy of therapies. Measurements and Main Results: CFTR genotype function exhibited a logarithmic relationship with each clinical feature. Modest increases in CFTR function related to differing genotypes were associated with clinically relevant improvements in cross-sectional FEV₁% predicted over a range of ages (6-82 yr). Therapeutic responses to modulators corresponded closely to predictions from the CFTR2-derived relationship between CFTR genotype function and phenotype. Conclusions: Increasing CFTR function in individuals with severe disease will have a proportionally greater effect on outcomes than similar increases in CFTR function in individuals with mild disease and should reverse a substantial fraction of the disease process. This study provides reference standards for clinical outcomes that may be achieved by increasing CFTR function.

Cystic fibrosis carriers are at increased risk for a wide range of cystic fibrosis-related conditions

Cystic fibrosis (CF) carriers are at increased risk for most of the conditions that commonly occur in people with CF. Given that there are more than 10 million CF carriers in the United States alone, the morbidity attributable to the CF carrier state is likely substantial. Thus, identifying CF carriers may aid in the prevention, diagnosis, and treatment of several common and uncommon disorders.

Autosomal recessive diseases, such as cystic fibrosis (CF), require inheritance of 2 mutated genes. However, some studies indicate that CF carriers are at increased risk for some conditions associated with CF. These investigations focused on single conditions and included small numbers of subjects. Our goal was to determine whether CF carriers are at increased risk for a range of CF-related conditions. Using the Truven Health MarketScan Commercial Claims database (2001–2017), we performed a population-based retrospective matched-cohort study. We identified 19,802 CF carriers and matched each carrier with 5 controls. The prevalence of 59 CF-related diagnostic conditions was evaluated in each cohort. Odds ratios for each condition were computed for CF carriers relative to controls. All 59 CF-related conditions were more prevalent among carriers compared with controls, with significantly increased risk (P < 0.05) for 57 conditions. Risk was increased for some conditions previously linked to CF carriers (e.g., pancreatitis, male infertility, bronchiectasis), as well as some conditions not previously reported (e.g., diabetes, constipation, cholelithiasis, short stature, failure to thrive). We compared our results with 23,557 subjects with CF, who were also matched with controls; as the relative odds of a given condition increased among subjects with CF, so did the corresponding relative odds for carriers (P < 0.001). Although individual-level risk remained low for most conditions, because there are more than 10 million carriers in the US, population-level morbidity attributable to the CF carrier state is likely substantial. Genetic testing may inform prevention, diagnosis, and treatment for a broad range of CF carrier-related conditions.

Modeling long-term health outcomes of patients with cystic fibrosis homozygous for F508del-CFTR treated with lumacaftor/ivacaftor

BACKGROUND

Lumacaftor/ivacaftor combination therapy is efficacious and generally safe for patients with cystic fibrosis (CF) homozygous for the F508del-CF transmembrane conductance regulator (CFTR) mutation. However, long-term survival benefits of lumacaftor/ivacaftor (LUM/IVA) cannot yet be quantified. Simulation models can provide predictions about long-term health outcomes. In this study, we aimed to project long-term health outcomes of LUM/IVA plus standard care (SC) in patients with CF homozygous for F508del-CFTR.

METHODS

This modeling study was an individual patient simulation in US patients aged ⩾6 years with CF, homozygous for F508del-CFTR. The primary outcome was projected survival among (a) a cohort of patients who ever initiated LUM/IVA, accounting for treatment discontinuations, and (b) a cohort of patients who remain on continuous LUM/IVA. Patient characteristics and model parameters were derived from clinical trials: VX14-809-109, VX13-809-011B, TRAFFIC/TRANSPORT, and PROGRESS; published literature; and the US CF Foundation Patient Registry.

RESULTS

Lumacaftor/ivacaftor + SC is expected to increase median survival by 6.1 years versus SC alone, accounting for treatment discontinuations. The incremental median predicted survival versus SC assuming initiation of LUM/IVA at ages 6, 12, 18, and 25 years was 17.7, 12.6, 8.0, and 3.8 years, respectively. Assuming lifetime treatment with LUM/IVA, incremental median survival was predicted to be 7.8 years longer in the LUM/IVA + SC cohort. Initiating LUM/IVA at ages 6, 12, 18, and 25 years and assuming lifetime treatment resulted in incremental median predicted survival of 23.4, 18.2, 11.0, and 4.8 years, respectively.

CONCLUSIONS

Lumacaftor/ivacaftor is projected to increase survival for patients with CF. Initiation at an early age and treatment persistence result in further increments in projected survival.

Cluster and CART analyses identify large subgroups of adults with cystic fibrosis at low risk of 10-year death

Our goal was to identify subgroups of adults with cystic fibrosis (CF) at low risk of death within 10 years.Factor analysis for mixed data followed by Ward's cluster analysis was conducted using 25 variables from 1572 French CF adults in 2005. Rates of death by subgroups were analysed over 10 years. An algorithm was developed using CART (classification and regression tree) analysis to provide rules for the identification of subgroups of CF adults with low rates of death within 10 years. This algorithm was validated in 1376 Canadian CF adults.Seven subgroups were identified by cluster analysis in French CF adults, including two subgroups with low (∼5%) rates of death at 10 years: one subgroup (22% of patients) was composed of patients with nonclassic CF, the other subgroup (17% of patients) was composed of patients with classic CF but low rates of Pseudomonas aeruginosa infection and diabetes. An algorithm based on CART analysis of data in 2005 allowed us to identify most French adults with low rates of death. When tested using data from Canadian CF adults in 2005, the algorithm identified 287 out of 1376 (21%) patients at low risk (10-year death: 7.7%).Large subgroups of CF adults share low risk of 10-year mortality.