Lentiviral Gene Therapy for Cystic Fibrosis: A Promising Approach and First-In-Human Trial.

Cystic fibrosis is a genetic disease caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. While cystic fibrosis is a multi-organ disease, the leading causes of morbidity and mortality are related to progressive lung disease. Current understanding of the effects of the broad spectrum of CFTR mutations on CFTR function has allowed for the development of CFTR modulator therapies. Despite the remarkable impact that these therapies have had, there remains a significant proportion of people with cystic fibrosis (estimated at 10-15% of the global cystic fibrosis population) who are genetically ineligible for, or intolerant to, current CFTR-targeting therapies and whose therapeutic needs remain unmet. Inhaled genetic therapies offer the prospect of addressing the unmet pulmonary treatment need in people with cystic fibrosis, with several approaches, including gene addition therapy (the focus of this review), RNA-based therapies, antisense oligonucleotides and gene editing, being explored. Various non-viral and viral vectors have been investigated for cystic fibrosis gene addition therapy for mutation-agnostic restoration of CFTR function in the lungs. Lentiviral vectors offer the prospect of highly efficient and long-lasting gene expression, and the potential to be safely and, in contrast to other commonly used viral vectors, effectively re-dosed. A third-generation lentiviral vector pseudotyped with Sendai virus F and HN envelope proteins (rSIV.F/HN) has been developed for the treatment of cystic fibrosis. Promising preclinical results support the progression of this vector carrying a full-length CFTR transgene (BI 3720931) into a first-in-human clinical trial expected to begin in 2024. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Pharmacological and pre-clinical safety profile of rSIV.F/HN, a hybrid lentiviral vector for cystic fibrosis gene therapy.

RATIONALE AND OBJECTIVE: Cystic fibrosis (CF) is caused by mutations in the CF Transmembrane Conductance Regulator (CFTR) gene. CFTR modulators offer significant improvements, but approximately 10% of patients remain nonresponsive or are intolerant. This study provides an analysis of rSIV.F/HN, a lentiviral vector optimized for lung delivery, including CFTR protein expression, functional correction of CFTR defects and genomic integration site analysis in preparation for a first-in-human clinical trial. METHODS: Air-liquid interface cultures of primary human bronchial epithelial cells (HBEC) from CF patients (F508del/F508del), as well as a CFTR-deficient immortalized human lung epithelial cell line mimicking Class I (CFTR-null) homozygous mutations, were used to assess transduction efficiency. Quantification methods included a novel proximity ligation assay (PLA) for CFTR protein expression. For assessment of CFTR channel activity, Ussing chamber studies were conducted. The safety profile was assessed using integration site analysis and in vitro insertional mutagenesis studies. RESULTS: rSIV.F/HN expressed CFTR and restored CFTR-mediated chloride currents to physiological levels in primary F508del/F508del HBECs as well as in a Class I cells. In contrast, the latter could not be achieved by small-molecule CFTR modulators, underscoring the potential of gene therapy for this mutation class. Combination of rSIV.F/HN-CFTR with the potentiator ivacaftor showed a greater than additive effect. The genomic integration pattern showed no site predominance (frequency of occurrence ≤10%), and a low risk of insertional mutagenesis was observed in an in vitro immortalization assay. CONCLUSIONS: The results underscore rSIV.F/HN as a promising gene therapy vector for CF, providing a mutation-agnostic treatment option.

Exploring the complexity of cystic fibrosis (CF) and psychosocial wellbeing in the 2020s: Current and future challenges.

Cystic fibrosis (CF) is traditionally associated with considerable and progressive multisystem pathology, onerous treatment burden, complex psychosocial challenges, and reduced life-expectancy [1-9].This decade has seen transformative change in management for many, but not all, people with CF. The most notable change comes from Cystic Fibrosis Transmembrane Receptor (CFTR) modulators, which bring significant benefits for people who are eligible for, and able to access, them [10]. However alongside, or perhaps because of, this exciting progress, the past few years have also brought important novel challenges to the psychosocial wellbeing of people with CF. This article, written as a collaboration between CF psychologists, social workers, physicians and nurses aims to provide an accessible overview of the novel psychosocial challenges now faced by children, their families, and adults with CF, and to invite consideration of their changing psychosocial requirements to inform future holistic care. Themes include geopolitical stressors such as the pandemic and its wake, a growing divide between those able or unable to access CFTR modulators, potential rapid changes in life expectancy secondary to these drugs and the inevitable associated challenges this brings; evolving body image, mental health side effects of CFTR modulators, the challenges of adherence in apparently well children and young adults, as well as the diagnostic conundrum and associated anxiety of the cystic fibrosis screen positive inconclusive diagnosis (CFSPID) label. It also highlights some unmet research and service delivery needs in the area.

Improvement in Lung Clearance Index and Chest Computed Tomography Scores with Elexacaftor/Tezacaftor/Ivacaftor Treatment in People with Cystic Fibrosis Aged 12 Years and Older - The RECOVER Trial.

Rationale: Clinical trials have shown that use of elexacaftor/tezacaftor/ivacaftor (ETI) is associated with improvements in sweat chloride, pulmonary function, nutrition, and quality of life in people with cystic fibrosis (CF). Little is known about the impact of ETI on ventilation inhomogeneity and lung structure. Objectives: RECOVER is a real-world study designed to measure the impact of ETI in people with CF. The primary endpoints were lung clearance (lung clearance index; LCI2.5) and FEV1. Secondary endpoints included spirometry-controlled chest computed tomography (CT) scores. Methods: The study was conducted in seven sites in Ireland and the United Kingdom. Participants ages 12 years and older who were homozygous for the F508del mutation (F508del/F508del) or heterozygous for F508del and a minimum-function mutation (F508del/MF) were recruited before starting ETI and were followed up over 12 months. LCI2.5 was measured using nitrogen multiple breath washout (MBW) at baseline and at 6 and 12 months. Spirometry was performed as per the criteria of the American Thoracic Society and the European Respiratory Society. Spirometry-controlled chest CT scans were performed at baseline and at 12 months. CT scans were scored using the Perth Rotterdam Annotated Grid Morphometric Analysis (PRAGMA) system. Other outcome measures include weight, height, Cystic Fibrosis Quality of Life Questionnaire-Revised (CFQ-R), and sweat chloride. Measurements and Main Results: One hundred seventeen people with CF ages 12 and older were recruited to the study. Significant improvements were seen in LCI scores (-2.5; 95% confidence interval [CI], -3.0, -2.0) and in the percents predicted for FEV1 (8.9; 95% CI, 7.0, 10.9), FVC (6.6; 95% CI, 4.9, 8.3), and forced expiratory flow between 25% and 75% of expired volume (12.4; 95% CI, 7.8, 17.0). Overall PRAGMA-CF scores reflecting airway disease improved significantly (-3.46; 95% CI, -5.23, -1.69). Scores for trapped air, mucus plugging, and bronchial wall thickening improved significantly, but bronchiectasis scores did not. Sweat chloride levels decreased in both F508del/F508del (-43.1; 95% CI, -47.4, -38.9) and F508del/MF (-42.8; 95% CI, -48.5, -37.2) groups. Scores on the Respiratory Domain of the CFQ-R improved by 14.2 points (95% CI, 11.3, 17.2). At 1 year, sweat chloride levels were significantly lower for the F508del/F508del group compared with scores for the F508del/MF group (33.93 vs. 53.36, P < 0.001). Conclusions: ETI is associated with substantial improvements in LCI2.5, spirometry, and PRAGMA-CF CT scores in people with CF ages 12 years and older. ETI led to improved nutrition and quality of life. People in the F508del/F508del group had significantly lower sweat chloride on ETI treatment compared with the F508del/MF group. Clinical trial registered with www.clinicaltrials.gov (NCT04602468).

Long-Term Safety and Efficacy of Elexacaftor/Tezacaftor/Ivacaftor in Children Aged ⩾6 Years with Cystic Fibrosis and at Least One F508del Allele: A Phase 3, Open-Label Clinical Trial.

Rationale: A 24-week, phase 3, open-label study showed elexacaftor/tezacaftor/ivacaftor (ELX/TEZ/IVA) was safe and efficacious in children aged 6-11 years with cystic fibrosis (CF) and one or more F508del-CFTR alleles. Objectives: To assess long-term safety and efficacy of ELX/TEZ/IVA in children who completed the pivotal 24-week phase 3 trial. Methods: In this phase 3, two-part (part A and part B), open-label extension study, children aged ⩾6 years with CF heterozygous for F508del and a minimal function CFTR mutation (F/MF genotypes) or homozygous for F508del (F/F genotype) who completed the 24-week parent study received ELX/TEZ/IVA based on weight. Children weighing <30 kg received ELX 100 mg once daily/TEZ 50 mg once daily/IVA 75 mg every 12 hours, whereas children weighing ⩾30 kg received ELX 200 mg once daily/TEZ 100 mg once daily/IVA 150 mg every 12 hours (adult dose). The 96-week analysis of part A of this extension study is reported here. Measurements and Main Results: Sixty-four children (F/MF genotypes, n = 36; F/F genotype, n = 28) were enrolled and received one or more doses of ELX/TEZ/IVA. Mean (SD) period of exposure to ELX/TEZ/IVA was 93.9 (11.1) weeks. The primary endpoint was safety and tolerability. Adverse events and serious adverse events were consistent with common manifestations of CF disease. Overall, exposure-adjusted rates of adverse events and serious adverse events (407.74 and 4.72 events per 100 patient-years) were lower than in the parent study (987.04 and 8.68 events per 100 patient-years). One child (1.6%) had an adverse event of aggression that was moderate in severity and resolved after study drug discontinuation. From parent study baseline at Week 96 of this extension study, the mean percent predicted FEV1 increased (11.2 [95% confidence interval (CI), 8.3 to 14.2] percentage points), sweat chloride concentration decreased (-62.3 [95% CI, -65.9 to -58.8] mmol/L), Cystic Fibrosis Questionnaire-Revised respiratory domain score increased (13.3 [95% CI, 11.4 to 15.1] points), and lung clearance index 2.5 decreased (-2.00 [95% CI, -2.45 to -1.55] units). Increases in growth parameters were also observed. The estimated pulmonary exacerbation rate per 48 weeks was 0.04. The annualized rate of change in percent predicted FEV1 was 0.51 (95% CI, -0.73 to 1.75) percentage points per year. Conclusions: ELX/TEZ/IVA continued to be generally safe and well tolerated in children aged ⩾6 years through an additional 96 weeks of treatment. Improvements in lung function, respiratory symptoms, and CFTR function observed in the parent study were maintained. These results demonstrate the favorable long-term safety profile and durable clinical benefits of ELX/TEZ/IVA in this pediatric population. Clinical trial registered with www.clinicaltrials.gov (NCT04183790).

What is cystic fibrosis screen positive inconclusive diagnosis? And what is it not?

Since screening for cystic fibrosis (CF) was incorporated into the newborn screening program, the number of recognised variants in the CF transmembrane conductance regulator (CFTR) gene has significantly increased. This has led to the discovery of combinations of gene variants with an uncertain prognosis. One outcome is the designation of 'cystic fibrosis screen positive inconclusive diagnosis' (CFSPID). While the majority of these children are expected to be unaffected by their CFTR variants, a small proportion have been seen to develop symptoms or increasing sweat chloride levels over time, which may reflect dysfunction of the CFTR protein.As the number of children with CFSPID increases, paediatricians and those working in primary care are more likely to encounter them in their practice. It is important that professionals have an understanding of CFSPID: what it is and, importantly, what it is not (ie, they do not have CF). In this article, we hope to explore this using some example cases, illustrating the ways in which these children may present symptomatically and how to manage them.

The clinical impact of Lumacaftor-Ivacaftor on structural lung disease and lung function in children aged 6-11 with cystic fibrosis in a real-world setting.

BACKGROUND: Data from clinical trials of lumacaftor-ivacaftor (LUM-IVA) demonstrate improvements in lung clearance index (LCI) but not in FEV1 in children with Cystic Fibrosis (CF) aged 6-11 years and homozygous for the Phe508del mutation. It is not known whether LUM/IVA use in children can impact the progression of structural lung disease. We sought to determine the real-world impact of LUM/IVA on lung structure and function in children aged 6-11 years. METHODS: This real-world observational cohort study was conducted across four paediatric sites in Ireland over 24-months using spirometry-controlled CT scores and LCI as primary outcome measures. Children commencing LUM-/IVA as part of routine care were included. CT scans were manually scored with the PRAGMA CF scoring system and analysed using the automated bronchus-artery (BA) method. Secondary outcome measures included rate of change of ppFEV1, nutritional indices and exacerbations requiring hospitalisation. RESULTS: Seventy-one participants were recruited to the study, 31 of whom had spirometry-controlled CT performed at baseline, and after one year and two years of LUM/IVA treatment. At two years there was a reduction from baseline in trapped air scores (0.13 to 0.07, p = 0.016), but an increase from baseline in the % bronchiectasis score (0.84 to 1.23, p = 0.007). There was no change in overall % disease score (2.78 to 2.25, p = 0.138). Airway lumen to pulmonary artery ratios (AlumenA ratio) were abnormal at baseline and worsened over the course of the study. In 28 participants, the mean annual change from baseline LCI2.5 (-0.055 (-0.61 to 0.50), p = 0.85) measurements over two years were not significant. Improvements from baseline in weight (0.10 (0.06 to 0.15, p < 0.0001), height (0.05 (0.02 to 0.09), p = 0.002) and BMI (0.09 (0.03 to 0.15) p = 0.005) z-scores were seen with LUM/IVA treatment. The mean annual change from baseline ppFEV1 (-2.45 (-4.44 to 2.54), p = 0.66) measurements over two years were not significant. CONCLUSION: In a real-world setting, the use of LUM/IVA over two years in children with CF aged 6-11 resulted in improvements in air trapping on CT but worsening in bronchiectasis scores. Our results suggest that LUM/IVA use in this age group improves air trapping but does not prevent progression of bronchiectasis over two years of treatment.

Efficacy and Safety of Elexacaftor/Tezacaftor/Ivacaftor in Children 6 Through 11 Years of Age with Cystic Fibrosis Heterozygous for F508del and a Minimal Function Mutation: A Phase 3b, Randomized, Placebo-controlled Study.

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

Cystic fibrosis.

Cystic fibrosis is a monogenic disease considered to affect at least 100 000 people worldwide. Mutations in CFTR, the gene encoding the epithelial ion channel that normally transports chloride and bicarbonate, lead to impaired mucus hydration and clearance. Classical cystic fibrosis is thus characterised by chronic pulmonary infection and inflammation, pancreatic exocrine insufficiency, male infertility, and might include several comorbidities such as cystic fibrosis-related diabetes or cystic fibrosis liver disease. This autosomal recessive disease is diagnosed in many regions following newborn screening, whereas in other regions, diagnosis is based on a group of recognised multiorgan clinical manifestations, raised sweat chloride concentrations, or CFTR mutations. Disease that is less easily diagnosed, and in some cases affecting only one organ, can be seen in the context of gene variants leading to residual protein function. Management strategies, including augmenting mucociliary clearance and aggressively treating infections, have gradually improved life expectancy for people with cystic fibrosis. However, restoration of CFTR function via new small molecule modulator drugs is transforming the disease for many patients. Clinical trial pipelines are actively exploring many other approaches, which will be increasingly needed as survival improves and as the population of adults with cystic fibrosis increases. Here, we present the current understanding of CFTR mutations, protein function, and disease pathophysiology, consider strengths and limitations of current management strategies, and look to the future of multidisciplinary care for those with cystic fibrosis.

Efficacy and safety of inhaled ENaC inhibitor BI 1265162 in patients with cystic fibrosis: BALANCE-CF 1, a randomised, phase II study.

BACKGROUND: Inhibition of the epithelial sodium channel (ENaC) in cystic fibrosis (CF) airways provides a mutation-agnostic approach that could improve mucociliary clearance in all CF patients. BI 1265162 is an ENaC inhibitor with demonstrated pre-clinical efficacy and safety already demonstrated in humans. OBJECTIVE: We present results from BALANCE-CFTM 1, a phase II, placebo-controlled, randomised, double-blind study of four dose levels of BI 1265162 versus placebo for 4 weeks on top of standard of care in adults and adolescents with CF. RESULTS: Initially, 28 randomised subjects (BI 1265162 200 µg twice daily n=14, placebo twice daily n=14) were assessed at an interim futility analysis. Compared with placebo, numerical changes of -0.8% (95% CI -6.6 to 4.9%) in percentage predicted forced expiratory volume in 1s (ppFEV1) and +2.1 units (95% CI -2.4 to 6.5 units) in lung clearance index (LCI) were observed in the active group, meeting a pre-defined stopping rule; accordingly, the study was terminated. Recruitment had continued during the interim analysis and pending results; 24 patients were added across three dose levels and placebo. The final results including these patients (+1.5% ppFEV1, 200 µg twice-daily dose versus placebo) were not supportive of relevant clinical effect. Furthermore, LCI change was not supportive, although interpretation was limited due to insufficient traces meeting quality criteria. A 9.4-point improvement in the Cystic Fibrosis Questionnaire - Revised Respiratory Domain was observed in the 200 µg twice daily dose group versus placebo. BI 1265162 up to 200 µg twice daily was safe and well-tolerated. Pharmacokinetics were similar to those in healthy volunteers. CONCLUSION: BI 1265162 was safe, but did not demonstrate a potential for clinical benefit. Development has been terminated.

Ivacaftor in Infants Aged 4 to <12 Months with Cystic Fibrosis and a Gating Mutation. Results of a Two-Part Phase 3 Clinical Trial.

Rationale: We previously reported that ivacaftor was safe and well tolerated in cohorts aged 12 to <24 months with cystic fibrosis and gating mutations in the ARRIVAL study; here, we report results for cohorts aged 4 to <12 months.Objectives: To evaluate the safety, pharmacokinetics, and pharmacodynamics of ivacaftor in infants aged 4 to <12 months with one or more gating mutations.Methods: ARRIVAL is a single-arm phase 3 study. Infants received 25 mg or 50 mg ivacaftor every 12 hours on the basis of age and weight for 4 days in part A and 24 weeks in part B.Measurements and Main Results: Primary endpoints were safety (parts A and B) and pharmacokinetics (part A). Secondary/tertiary endpoints (part B) included pharmacokinetics and changes in sweat chloride levels, growth, and markers of pancreatic function. Twenty-five infants received ivacaftor, 12 in part A and 17 in part B (four infants participated in both parts). Pharmacokinetics was consistent with that in older groups. Most adverse events were mild or moderate. In part B, cough was the most common adverse event (n = 10 [58.8%]). Five infants (part A, n = 1 [8.3%]; part B, n = 4 [23.5%]) had serious adverse events, all of which were considered to be not or unlikely related to ivacaftor. No deaths or treatment discontinuations occurred. One infant (5.9%) experienced an alanine transaminase elevation >3 to ≤5× the upper limit of normal at Week 24. No other adverse trends in laboratory tests, vital signs, or ECG parameters were reported. Sweat chloride concentrations and measures of pancreatic obstruction improved.Conclusions: This study of ivacaftor in the first year of life supports treating the underlying cause of cystic fibrosis in children aged ≥4 months with one or more gating mutations.Clinical trial registered with clinicaltrials.gov (NCT02725567).

Pseudomonas aeruginosa in the Cystic Fibrosis Lung.

Cystic fibrosis is a common genetically inherited, multisystem disorder caused by loss of function of the cystic fibrosis transmembrane conductance regulator (CFTR) protein, an apically situated anion channel. In the lung, lack of CFTR leads to airway surface dehydration, mucociliary clearance failure and an acidic pH in which innate defence molecules are rendered ineffective. Infection occurs early in life, with P. aeruginosa dominating by adolescence. The characteristic features of the CF airway highlighted above encourage persistence of infection, but P. aeruginosa also possess an array of mechanisms with which they attack host defences and render themselves protected from antimicrobials. Early eradication is usually successful, but this is usually transient. Chronic infection is manifest by biofilm formation which is resistant to treatment. Outcomes for people with CF have improved greatly in the last few decades, but particularly so with the recent advent of small molecule CFTR modulators. However, despite impressive efficacy on lung function and exacerbation frequency, most people with chronic infection remain with their pathogens. There is an active pipeline of new treatments including anti-biofilm and anti-quorum sensing molecules and non-drug approaches such as bacteriophage. Studies are reviewed and challenges for future drug development considered.

VX-659-Tezacaftor-Ivacaftor in Patients with Cystic Fibrosis and One or Two Phe508del Alleles.

BACKGROUND: The next-generation cystic fibrosis transmembrane conductance regulator (CFTR) corrector VX-659, in triple combination with tezacaftor and ivacaftor (VX-659-tezacaftor-ivacaftor), was developed to restore the function of Phe508del CFTR protein in patients with cystic fibrosis. METHODS: We evaluated the effects of VX-659-tezacaftor-ivacaftor on the processing, trafficking, and function of Phe508del CFTR protein using human bronchial epithelial cells. A range of oral VX-659-tezacaftor-ivacaftor doses in triple combination were then evaluated in randomized, controlled, double-blind, multicenter trials involving patients with cystic fibrosis who were heterozygous for the Phe508del CFTR mutation and a minimal-function CFTR mutation (Phe508del-MF genotypes) or homozygous for the Phe508del CFTR mutation (Phe508del-Phe508del genotype). The primary end points were safety and the absolute change from baseline in the percentage of predicted forced expiratory volume in 1 second (FEV1). RESULTS: VX-659-tezacaftor-ivacaftor significantly improved the processing and trafficking of Phe508del CFTR protein as well as chloride transport in vitro. In patients, VX-659-tezacaftor-ivacaftor had an acceptable safety and side-effect profile. Most adverse events were mild or moderate. VX-659-tezacaftor-ivacaftor resulted in significant mean increases in the percentage of predicted FEV1 through day 29 (P<0.001) of up to 13.3 points in patients with Phe508del-MF genotypes; in patients with the Phe508del-Phe508del genotype already receiving tezacaftor-ivacaftor, adding VX-659 resulted in a further 9.7-point increase in the percentage of predicted FEV1. The sweat chloride concentrations and scores on the respiratory domain of the Cystic Fibrosis Questionnaire-Revised improved in both patient populations. CONCLUSIONS: Robust in vitro activity of VX-659-tezacaftor-ivacaftor targeting Phe508del CFTR protein translated into improvements for patients with Phe508del-MF or Phe508del-Phe508del genotypes. VX-659 triple-combination regimens have the potential to treat the underlying cause of disease in approximately 90% of patients with cystic fibrosis. (Funded by Vertex Pharmaceuticals; VX16-659-101 and VX16-659-001 ClinicalTrials.gov numbers, NCT03224351 and NCT03029455 .).

Transepithelial nasal potential difference in patients with, and at risk of acute respiratory distress syndrome.

BACKGROUND: Impaired alveolar fluid clearance, determined in part by alveolar sodium transport, is associated with acute respiratory distress syndrome (ARDS). Nasal sodium transport may reflect alveolar transport. The primary objective of this prospective, observational study was to determine if reduced nasal sodium transport, as measured by nasal potential difference (NPD), was predictive of the development of and outcome from ARDS. METHODS: NPD was measured in 15 healthy controls and in 88 patients: 40 mechanically ventilated patients defined as 'at-risk' for ARDS, 61 mechanically ventilated patients with ARDS (13 who were previously included in the 'at-risk' group) and 8 ARDS survivors on the ward. RESULTS: In at-risk subjects, maximum NPD (mNPD) was greater in those who developed ARDS (difference -8.4 mV; 95% CI -13.8 to -3.7; p=0.005) and increased mNPD predicted the development of ARDS before its onset (area under the curve (AUC) 0.75; 95% CI 0.59 to 0.89). In the ARDS group, mNPD was not significantly different for survivors and non-survivors (p=0.076), and mNPD was a modest predictor of death (AUC 0.60; 95% CI 0.45 to 0.75). mNPD was greater in subjects with ARDS (-30.8 mV) than in at-risk subjects (-24.2 mV) and controls (-19.9 mV) (p<0.001). NPD values were not significantly different for survivors and controls (p=0.18). CONCLUSIONS: Increased NPD predicts the development of ARDS in at-risk subjects but does not predict mortality. NPD increases before ARDS develops, is greater during ARDS, but is not significantly different for controls and survivors. These results may reflect the upregulated sodium transport necessary for alveolar fluid clearance in ARDS. NPD may be useful as a biomarker of endogenous mechanisms to stimulate sodium transport. Larger studies are now needed to confirm these associations and predictive performance.

Time to get serious about the detection and monitoring of early lung disease in cystic fibrosis.

Structural and functional defects within the lungs of children with cystic fibrosis (CF) are detectable soon after birth and progress throughout preschool years often without overt clinical signs or symptoms. By school age, most children have structural changes such as bronchiectasis or gas trapping/hypoperfusion and lung function abnormalities that persist into later life. Despite improved survival, gains in forced expiratory volume in one second (FEV1) achieved across successive birth cohorts during childhood have plateaued, and rates of FEV1 decline in adolescence and adulthood have not slowed. This suggests that interventions aimed at preventing lung disease should be targeted to mild disease and commence in early life. Spirometry-based classifications of 'normal' (FEV1≥90% predicted) and 'mild lung disease' (FEV1 70%-89% predicted) are inappropriate, given the failure of spirometry to detect significant structural or functional abnormalities shown by more sensitive imaging and lung function techniques. The state and readiness of two imaging (CT and MRI) and two functional (multiple breath washout and oscillometry) tools for the detection and monitoring of early lung disease in children and adults with CF are discussed in this article.Prospective research programmes and technological advances in these techniques mean that well-designed interventional trials in early lung disease, particularly in young children and infants, are possible. Age appropriate, randomised controlled trials are critical to determine the safety, efficacy and best use of new therapies in young children. Regulatory bodies continue to approve medications in young children based on safety data alone and extrapolation of efficacy results from older age groups. Harnessing the complementary information from structural and functional tools, with measures of inflammation and infection, will significantly advance our understanding of early CF lung disease pathophysiology and responses to therapy. Defining clinical utility for these novel techniques will require effective collaboration across multiple disciplines to address important remaining research questions. Future impact on existing management burden for patients with CF and their family must be considered, assessed and minimised.To address the possible role of these techniques in early lung disease, a meeting of international leaders and experts in the field was convened in August 2019 at the Australiasian Cystic Fibrosis Conference. The meeting entitiled 'Shaping imaging and functional testing for early disease detection of lung disease in Cystic Fibrosis', was attended by representatives across the range of disciplines involved in modern CF care. This document summarises the proceedings, key priorities and important research questions highlighted.

Clinical pharmacokinetics and dose recommendations for posaconazole gastroresistant tablets in children with cystic fibrosis.

OBJECTIVES: To investigate the population pharmacokinetics of posaconazole gastroresistant tablets in children with cystic fibrosis (CF) and perform simulations to recommend optimal doses. PATIENTS AND METHODS: Children from a paediatric CF centre who had received posaconazole tablets and underwent therapeutic drug monitoring were identified from pharmacy records. Relevant clinical data were collated from case notes and electronic patient records and used to develop an allometrically scaled population pharmacokinetic model. A stepwise covariate model-building exercise evaluated the influence of interacting medicines and liver function. RESULTS: One hundred posaconazole serum concentrations were collected from 37 children with a median age of 14 years (range 7-17). Posaconazole pharmacokinetics were adequately described by a one-compartment model with inter-individual variability on clearance. Dose simulations demonstrated a 77%-83% probability of attaining a trough target of 1 mg/L with a dose of 300 mg every 12 h for two doses then 300 mg once daily (OD) in children aged 6-11 years; and 86%-88% with a dose of 400 mg every 12 h for two doses then 400 mg OD in adolescents aged 12-17 years. This dose scheme also yielded a 90% probability of achieving an AUC of 30 mg·h/L. AUC and trough concentration were highly correlated (r2 = 0.98). Simulations showed that trough concentrations of >0.75 mg/L would exceed an AUC of 30 mg·h/L in 90% of patients. CONCLUSIONS: A starting dose of 300 mg OD in those aged 6-11 years and 400 mg OD in those aged 12-17 years (following loading doses) yields a 90% probability of attaining an AUC of 30 mg·h/L.

Response of Pseudomonas aeruginosa to the Innate Immune System-Derived Oxidants Hypochlorous Acid and Hypothiocyanous Acid.

Pseudomonas aeruginosa is a significant nosocomial pathogen and is associated with lung infections in cystic fibrosis (CF). Once established, P. aeruginosa infections persist and are rarely eradicated despite host immune cells producing antimicrobial oxidants, including hypochlorous acid (HOCl) and hypothiocyanous acid (HOSCN). There is limited knowledge as to how P. aeruginosa senses, responds to, and protects itself against HOCl and HOSCN and the contribution of such responses to its success as a CF pathogen. To investigate the P. aeruginosa response to these oxidants, we screened 707 transposon mutants, with mutations in regulatory genes, for altered growth following HOCl exposure. We identified regulators of antibiotic resistance, methionine biosynthesis, catabolite repression, and PA14_07340, the homologue of the Escherichia coli HOCl-sensor RclR (30% identical), which are required for protection against HOCl. We have shown that RclR (PA14_07340) protects specifically against HOCl and HOSCN stress and responds to both oxidants by upregulating the expression of a putative peroxiredoxin, rclX (PA14_07355). Transcriptional analysis revealed that while there was specificity in the response to HOCl (231 genes upregulated) and HOSCN (105 genes upregulated), there was considerable overlap, with 74 genes upregulated by both oxidants. These included genes encoding the type 3 secretion system, sulfur and taurine transport, and the MexEF-OprN efflux pump. RclR coordinates part of the response to both oxidants, including upregulation of pyocyanin biosynthesis genes, and, in the presence of HOSCN, downregulation of chaperone genes. These data indicate that the P. aeruginosa response to HOCl and HOSCN is multifaceted, with RclR playing an essential role.IMPORTANCE The bacterial pathogen Pseudomonas aeruginosa causes devastating infections in immunocompromised hosts, including chronic lung infections in cystic fibrosis patients. To combat infection, the host's immune system produces the antimicrobial oxidants hypochlorous acid (HOCl) and hypothiocyanous acid (HOSCN). Little is known about how P. aeruginosa responds to and survives attack from these oxidants. To address this, we carried out two approaches: a mutant screen and transcriptional study. We identified the P. aeruginosa transcriptional regulator, RclR, which responds specifically to HOCl and HOSCN stress and is essential for protection against both oxidants. We uncovered a link between the P. aeruginosa transcriptional response to these oxidants and physiological processes associated with pathogenicity, including antibiotic resistance and the type 3 secretion system.

Tezacaftor-Ivacaftor in Residual-Function Heterozygotes with Cystic Fibrosis.

BACKGROUND: Cystic fibrosis is an autosomal recessive disease caused by mutations in the CFTR gene that lead to progressive respiratory decline. Some mutant CFTR proteins show residual function and respond to the CFTR potentiator ivacaftor in vitro, whereas ivacaftor alone does not restore activity to Phe508del mutant CFTR. METHODS: We conducted a randomized, double-blind, placebo-controlled, phase 3, crossover trial to evaluate the efficacy and safety of ivacaftor alone or in combination with tezacaftor, a CFTR corrector, in 248 patients 12 years of age or older who had cystic fibrosis and were heterozygous for the Phe508del mutation and a CFTR mutation associated with residual CFTR function. Patients were randomly assigned to one of six sequences, each involving two 8-week intervention periods separated by an 8-week washout period. They received tezacaftor-ivacaftor, ivacaftor monotherapy, or placebo. The primary end point was the absolute change in the percentage of predicted forced expiratory volume in 1 second (FEV1) from the baseline value to the average of the week 4 and week 8 measurements in each intervention period. RESULTS: The number of analyzed intervention periods was 162 for tezacaftor-ivacaftor, 157 for ivacaftor alone, and 162 for placebo. The least-squares mean difference versus placebo with respect to the absolute change in the percentage of predicted FEV1 was 6.8 percentage points for tezacaftor-ivacaftor and 4.7 percentage points for ivacaftor alone (P<0.001 for both comparisons). Scores on the respiratory domain of the Cystic Fibrosis Questionnaire-Revised, a quality-of-life measure, also significantly favored the active-treatment groups. The incidence of adverse events was similar across intervention groups; most events were mild or moderate in severity, with no discontinuations of the trial regimen due to adverse events for tezacaftor-ivacaftor and few for ivacaftor alone (1% of patients) and placebo (<1%). CONCLUSIONS: CFTR modulator therapy with tezacaftor-ivacaftor or ivacaftor alone was efficacious in patients with cystic fibrosis who were heterozygous for the Phe508del deletion and a CFTR residual-function mutation. (Funded by Vertex Pharmaceuticals and others; EXPAND ClinicalTrials.gov number, NCT02392234 .).

Cephalosporin nitric oxide-donor prodrug DEA-C3D disperses biofilms formed by clinical cystic fibrosis isolates of Pseudomonas aeruginosa.

OBJECTIVES: The cephalosporin nitric oxide (NO)-donor prodrug DEA-C3D ('DiEthylAmin-Cephalosporin-3'-Diazeniumdiolate') has been shown to initiate the dispersal of biofilms formed by the Pseudomonas aeruginosa laboratory strain PAO1. In this study, we investigated whether DEA-C3D disperses biofilms formed by clinical cystic fibrosis (CF) isolates of P. aeruginosa and its effect in combination with two antipseudomonal antibiotics, tobramycin and colistin, in vitro. METHODS: ß-Lactamase-triggered release of NO from DEA-C3D was confirmed using a gas-phase chemiluminescence detector. MICs for P. aeruginosa clinical isolates were determined using the broth microdilution method. A crystal violet staining technique and confocal laser scanning microscopy were used to evaluate the effects of DEA-C3D on P. aeruginosa biofilms alone and in combination with tobramycin and colistin. RESULTS: DEA-C3D was confirmed to selectively release NO in response to contact with bacterial ß-lactamase. Despite lacking direct, cephalosporin/ß-lactam-based antibacterial activity, DEA-C3D was able to disperse biofilms formed by three P. aeruginosa clinical isolates. Confocal microscopy revealed that DEA-C3D in combination with tobramycin produces similar reductions in biofilm to DEA-C3D alone, whereas the combination with colistin causes near complete eradication of P. aeruginosa biofilms in vitro. CONCLUSIONS: DEA-C3D is effective in dispersing biofilms formed by multiple clinical isolates of P. aeruginosa and could hold promise as a new adjunctive therapy to patients with CF.

Monitoring early stage lung disease in cystic fibrosis.

PURPOSE OF REVIEW: Early stage lung disease has long been synonymous with infancy and childhood. As diagnosis happens earlier and conventional management improves, we are seeing larger proportions of people with cystic fibrosis (CF) in adolescence and even adulthood with well preserved lung health. The availability of highly effective cystic fibrosis transmembrane conductance regulator modulator drugs for a large proportion of the CF population will impact even further. Transitioning into adult care with 'normal' lung function will become more common. However, it is crucial that we are not blasé about this phase, which sets the scene for future lung health. It is well recognized that lung function assessed by spirometry is insensitive to 'early' changes occurring in the distal, small airways. Much of our learning has come from studies in infants and young children, which have allowed assessment and optimization of alternative forms of monitoring. RECENT FINDINGS: Here, as a group of paediatric and adult CF specialists, we review the evidence base for sensitive physiological testing based on multibreath washout, lung imaging, exercise and activity monitoring, assessment of infection and quality of life measures. SUMMARY: We seek to emphasise the importance of further work in these areas, as outcome measures become widely applicable to a growing CF population.