Sweat chloride reflects CFTR function and correlates with clinical outcomes following CFTR modulator treatment.

Background: Highly effective CFTR modulators improve CFTR function and lead to dramatic improvements in health outcomes in many people with cystic fibrosis (pwCF). The relationship between measures of CFTR function, such as sweat chloride concentration, and clinical outcomes in pwCF treated with CFTR modulators is poorly defined. We conducted analyses to better understand the relationships between sweat chloride and CFTR function in vitro, and between sweat chloride and clinical outcomes following CFTR modulator treatment.

Qualitative understanding of experiences of people with cystic fibrosis in a treatment discontinuation trial: The QUEST study.

Background: As people with cystic fibrosis (PWCF) live longer due to the breakthrough drug elexacaftor-tezacaftor-ivacaftor (ETI), they have questioned whether other CF therapies could be safely discontinued. SIMPLIFY was the first prospective, randomized trial to evaluate non-inferiority of discontinuing versus continuing two therapies. The QUEST (Qualitative Understanding of Experiences in the SIMPLIFY Trial) study was conducted to understand experiences of PWCF enrolled in SIMPLIFY, including why they joined, perceptions of randomization, decision-making around study withdrawal, and considerations for future discontinuation studies.

Self-reported chronic therapy use after 24-weeks of follow-up by participants who completed the simplify randomized, controlled trial.

Background: Highly effective CFTR modulator therapy (HEMT) has improved the health of many people with cystic fibrosis (pwCF), offering opportunities to discontinue burdensome therapies. SIMPLIFY included randomized, controlled trials that confirmed non-inferiority of discontinuing versus continuing dornase alfa (DA) or hypertonic saline (HS) for 6 weeks in pwCF on HEMT. In this study of post-trial treatment use by SIMPLIFY participants, we hypothesized that randomization to discontinue DA or HS during the trial would be associated with a higher likelihood of non-use of each medication during follow-up.

Characteristics of individuals with cystic fibrosis in the United States ineligible for ivacaftor and elexacaftor/tezacaftor/ivacaftor.

Background: We characterized people with cystic fibrosis (CF) ineligible by genotype (not age) for currently approved CFTR modulator therapy using data from the US CF Foundation Patient Registry (CFFPR).

Methods: We summarized clinical characteristics using CFFPR data from 2017 to 2022. Annual rate of change in percent predicted of forced expiratory volume in one second (ppFEV) was estimated using generalized estimating equations.

Impact of Discontinuing Both Hypertonic Saline and Dornase Alfa after Elexacaftor-Tezacaftor-Ivacaftor in Cystic Fibrosis.

Evaluating approaches to reduce treatment burden is a research priority among people with cystic fibrosis on highly effective modulators, including elexacaftor-tezacaftor-ivacaftor (ETI). We sought to evaluate the impact of discontinuing both hypertonic saline (HS) and dornase alfa (DA) versus continuing both therapies among a subgroup of participants in the SIMPLIFY study who sequentially participated in trials evaluating the independent clinical effects of discontinuing HS and DA. SIMPLIFY participants ≥12 years old on ETI and constituting a subgroup using both HS and DA at study entry were randomized to the HS or DA trial and then randomized 1:1 to continue or discontinue the applicable therapy for 6 weeks.

Statistical approaches for the integration of external controls in a cystic fibrosis clinical trial: a simulation and an application.

Development of new therapeutics for a rare disease such as cystic fibrosis is hindered by challenges in accruing enough patients for clinical trials. Use of external controls from well-matched historical trials can reduce prospective trial sizes, and this approach has supported regulatory approval of new interventions for other rare diseases. Here we consider 3 statistical methods that incorporate external controls into a hypothetical clinical trial of a new treatment to reduce pulmonary exacerbations in cystic fibrosis patients: (1) inverse probability weighting, (2) bayesian modeling with propensity-score-based power priors, and (3) hierarchical bayesian modeling with commensurate priors.

Heterogeneity of CFTR modulator-induced sweat chloride concentrations in people with cystic fibrosis.

Background: Sweat chloride (SC) concentrations in people with cystic fibrosis (PwCF) reflect relative CF transmembrane conductance regulator (CFTR) protein function, the primary CF defect. Populations with greater SC concentrations tend to have lesser CFTR function and more severe disease courses. CFTR modulator treatment can improve CFTR function within specific CF genotypes and is commonly associated with reduced SC concentration.

The effect of discontinuing hypertonic saline or dornase alfa on mucociliary clearance in elexacaftor/tezacaftor/ivacaftor treated people with cystic fibrosis: The SIMPLIFY-MCC Study.

Many people with CF (pwCF) desire a reduction in inhaled treatment burden after initiation of elexacaftor/tezacaftor/ivacaftor. The randomized, open-label SIMPLIFY study showed that discontinuing hypertonic saline (HS) or dornase alfa (DA) was non-inferior to continuation of each treatment with respect to change in lung function over a 6-week period. In this SIMPLIFY substudy, we used gamma scintigraphy to determine whether discontinuation of either HS or DA was associated with deterioration in the rate of in vivo mucociliary clearance (MCC) in participants ≥12 years of age.

The cost of simplifying treatments for cystic fibrosis: Implications of the SIMPLIFY trial.

Background: Dornase alfa and hypertonic saline are mucoactive therapies that can improve respiratory symptoms in people with cystic fibrosis (CF). A recent randomized control trial showed that participants with well-preserved pulmonary function taking elexacaftor + tezacaftor + ivacaftor (ETI) who discontinued dornase alfa or hypertonic saline for 6 weeks had no clinically meaningful decline in lung function. This may prompt discussions with care providers regarding ongoing use of these medications.

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.

Limited effects of azithromycin on the oropharyngeal microbiome in children with CF and early pseudomonas infection.

Background: Tobramycin inhalation solution (TIS) and chronic azithromycin (AZ) have known clinical benefits for children with CF, likely due to antimicrobial and anti-inflammatory activity. The effects of chronic AZ in combination with TIS on the airway microbiome have not been extensively investigated. Oropharyngeal swab samples were collected in the OPTIMIZE multicenter, randomized, placebo-controlled trial examining the addition of AZ to TIS in 198 children with CF and early P.

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.

Understanding and addressing the needs of people with cystic fibrosis in the era of CFTR modulator therapy.

Cystic fibrosis is a multiorgan disease caused by impaired function of the cystic fibrosis transmembrane conductance regulator (CFTR). Since the introduction of the CFTR modulator combination elexacaftor-tezacaftor-ivacaftor (ETI), which acts directly on mutant CFTR to enhance its activity, most people with cystic fibrosis (pwCF) have seen pronounced reductions in symptoms, and studies project marked increases in life expectancy for pwCF who are eligible for ETI. However, modulator therapy has not cured cystic fibrosis and the success of CFTR modulators has resulted in immediate questions about the new state of cystic fibrosis disease and clinical challenges in the care of pwCF.

Willingness of people with cystic fibrosis receiving elexacaftor/tezacaftor/ivacaftor (ETI) to participate in randomized modulator and inhaled antimicrobial clinical trials.

Objective: To assess the feasibility of enrolling people with CF (pwCF) taking the CFTR modulator elexacaftor/tezacaftor/ivacaftor (ETI) in clinical trials of a new modulator.

Methods: PwCF receiving ETI at CHEC-SC study (NCT03350828) enrollment were surveyed for interest in 2-week to 6-month placebo- (PC) and active-comparator (AC) modulator studies. Those taking inhaled antimicrobials (inhABX) were surveyed for interest in PC inhABX studies.

Lung Function Decline in Cystic Fibrosis: Impact of Data Availability and Modeling Strategies on Clinical Interpretations.

Studies estimating the rate of lung function decline in cystic fibrosis have been inconsistent regarding the methods used. How the methodology used impacts the validity of the results and comparability between studies is unknown. The Cystic Fibrosis Foundation established a work group whose tasks were to examine the impact of differing approaches to estimating the rate of decline in lung function and to provide analysis guidelines.

Eradication of early MRSA infection in cystic fibrosis: a novel study design for the STAR-ter trial.

Introduction: Early eradication of methicillin-resistant (MRSA) in cystic fibrosis is desirable. Prospective studies are challenging owing to the feasibility of recruiting patients with a rare event in an orphan disease. Our prior randomised study ( Resistance-Treat Or Observe (STAR-too)) showed improved clearance and outcomes with aggressive therapy compared to no treatment.

Discontinuation versus continuation of hypertonic saline or dornase alfa in modulator treated people with cystic fibrosis (SIMPLIFY): results from two parallel, multicentre, open-label, randomised, controlled, non-inferiority trials.

Background: Reducing treatment burden is a priority for people with cystic fibrosis, whose health has benefited from using new modulators that substantially increase CFTR protein function. The SIMPLIFY study aimed to assess the effects of discontinuing nebulised hypertonic saline or dornase alfa in individuals using the CFTR modulator elexacaftor plus tezacaftor plus ivacaftor (ETI).

Methods: The SIMPLIFY study included two parallel, multicentre, open-label, randomised, controlled, non-inferiority trials at 80 participating clinics across the USA in the Cystic Fibrosis Therapeutics Development Network.

Rate of Lung Function Decline in People with Cystic Fibrosis Having a Residual Function Gene Mutation.

Introduction: Cystic fibrosis (CF) is an autosomal recessive disease caused by mutations in the CF transmembrane conductance regulator (CFTR) gene. Approximately 5% of people with CF have residual function (RF) CFTR mutations that result in partially retained CFTR activity. Published literature on disease trajectory among those with RF mutations is limited.

Characterizing CFTR modulated sweat chloride response across the cf population: Initial results from the CHEC-SC study.

Background: CHEC-SC is an ongoing epidemiologic study characterizing modulator-induced sweat chloride (SC) responses across the CF population, with interim results available prior to the availability of triple combination modulator therapy.

Methods: Eligible participants had been prescribed a modulator for ≥90 days with re-enrollment allowed upon establishment of a new modulator. Pre-modulator SC values were obtained from chart review; post-modulator sweat was collected and analyzed locally.

Prospectively evaluating maternal and fetal outcomes in the era of CFTR modulators: the MAYFLOWERS observational clinical trial study design.

Introduction: Therapeutic advances have markedly increased life expectancy for those with cystic fibrosis (CF), resulting in a median predicted survival over 50 years. Consequently, people with CF (pwCF) are living through their reproductive years and the rate of pregnancy is rapidly rising. Despite the increased relevance of this topic, multicentre studies investigating the association between maternal health and choices made during pregnancy on maternal and fetal outcomes do not exist.

Development and Internal Validation of a Prognostic Model of the Probability of Death or Lung Transplantation Within 2 Years for Patients With Cystic Fibrosis and FEV ≤ 50% Predicted.

Background: Improved methods are needed to risk-stratify patients with cystic fibrosis (CF) and reduced FEV.

Research Questions: What are the predictors of death or lung transplantation (LTx) within 2 years among patients with CF whose FEV ≤ 50% predicted? Do these markers similarly predict outcomes among G551D patients taking ivacaftor since 2012?

Study Design And Methods: Patients with CF, age ≥ 6 years with FEV ≤ 50% predicted as of December 31, 2014, were identified in a data set that merged Cystic Fibrosis Foundation and United Network for Organ Sharing (UNOS) registries. The least absolute shrinkage and selection operator (LASSO) method was applied to a randomly selected training set to select important prognostic variables.