Levelling the playing field through the London Network of the UK clinical trials accelerator platform.

Cystic fibrosis (CF) is a multisystem, genetic disease with a significantly reduced life expectancy. Despite substantial progress in therapies in the last 10-15 years, there is still no cure. There are dozens of drugs in the development pipeline and multiple clinical trials are being conducted across the globe. The UK Cystic Fibrosis Trust's (CFT) Clinical Trials Accelerator Platform (CTAP) is a national initiative bringing together 25 UK based CF centres to support the CF community in accessing and participating in CF clinical trials. CTAP enables more CF centres to run a broader portfolio of trials and increases the range of CF studies available for UK patients. There are four large specialist CF centres based in London, all within a small geographical region as well as two smaller centres which deliver CF care. At the launch of CTAP, these centres formed a sub-network in a consortium-style collaboration. The purpose of the network was to ensure equity of access to trials for patients across the UK's capital, and to share experience and knowledge. Four years into the programme we have reviewed our practices through working group meetings and an online survey. We sought to identify strengths and areas for improvement. We share our findings here, as we believe they are relevant to others delivering research in regions outside of London and in other chronic diseases.

Standards for the care of people with cystic fibrosis (CF); Planning for a longer life.

This is the final of four papers updating standards for the care of people with CF. That this paper "Planning a longer life" was considered necessary, highlights how much CF care has progressed over the past decade. Several factors underpin this progress, notably increased numbers of people with CF with access to CFTR modulator therapy. As the landscape for CF changes, so do the hopes and aspirations of people with CF and their families. This paper reflects the need to consider people with CF not as a "problem" to be solved, but as a success, a potential and a voice to be heard. People with CF and the wider CF community have driven this approach, reflecting many of the topics in this paper. This exercise involved wide stakeholder engagement. People with CF are keen to contribute to research priorities and be involved in all stages of research. People with CF want healthcare professionals to respect them as individuals and consider the impact of our actions on the world around us. Navigating life presents challenges to all, but for people with CF these challenges are heightened and complex. In this paper we highlight the concerns and life moments that impact people with CF, and events that the CF team should aim to support, including the challenges around having a family. People with CF and their care teams must embrace the updated standards outlined in these four papers to enjoy the full potential for a healthier life.

An exploration of managing emotional labour and maintaining professional integrity in children's hospice nursing.

BACKGROUND: Research exploring nurse-parent relationships in children's hospices is rare. AIM: To investigate how children's hospice nurses manage emotional labour and professional integrity in their long-term relationships with parents. METHODS: A purposive sample of six children's nurses, from hospices across England, recorded audio diaries and participated in telephone interviews. Narratives were thematically analysed. FINDINGS: Three overarching, cross-cutting themes were identified-purposeful positioning; balancing personability and professionalism; coping with and counterbalancing emotional labour. All themes were indicative of and/or built upon emotional intelligence constructs, such as self-awareness, self-regulation, appropriate (managed) empathy, social skills and intrinsic motivation. Innate features of children's hospice work were important for perpetuating intrinsic motivation and satisfaction. CONCLUSION: This study provided an insight into the management of emotional labour and professional integrity by experienced children's hospice nurses. The identification of emotional intelligence skills merits further exploration in this environment, as well as other children's palliative care settings.

Safety and efficacy of ivacaftor in infants aged 1 to less than 4 months with cystic fibrosis.

BACKGROUND: Ivacaftor (IVA) has been shown to be safe and efficacious in children aged ≥4 months with cystic fibrosis (CF) and CFTR gating variants. We evaluated safety, pharmacokinetics (PK), and efficacy of IVA in a small cohort of infants aged 1 to <4 months with CF. METHODS: In this phase 3, open-label study, infants 1 to <4 months with CF and an IVA-responsive CFTR variant received an initial low dose of IVA based on age and weight. Because IVA is a sensitive CYP3A substrate and CYP3A maturation is uncertain in infants, doses were adjusted at day 15 to better match median adult exposures based on individual PK measurements taken on day 4. Primary endpoints were safety and PK measurements. RESULTS: Seven infants (residual function CFTR variants [n=5]; minimal function CFTR variants [n=2]) received ≥1 dose of IVA. Six infants had doses adjusted at day 15 and one infant did not require dose adjustment; subsequent PK analyses showed mean trough concentrations for IVA and metabolites were within range of prior clinical experience. Four infants (57.1%) had adverse events (AEs); no serious AEs were noted. One infant discontinued study drug due to a non-serious AE of elevated alanine aminotransferase >8x the upper limit of normal. Mean sweat chloride concentration decreased (-40.3 mmol/L [SD: 29.2]) through week 24. Improvements in biomarkers of pancreatic function and intestinal inflammation, as well as growth parameters, were observed. CONCLUSIONS: In this small, open-label study, IVA dosing in infants achieved exposures previously shown to be safe and efficacious. Because PK was predictable, a dosing regimen based on age and weight is proposed. IVA was generally safe and well tolerated, and led to improvements in CFTR function, markers of pancreatic function and intestinal inflammation, and growth parameters, supporting use in infants as young as 1 month of age.

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.

How representative are clinical trial cohorts of the general CF population? Implications for trial planning.

Understanding the number of patients eligible to participate in research is important to design protocols and define research priorities. We reviewed the records of all patients with CF, age 12+, who receive care at our centre. We assessed their eligibility for trial participation based on common trial inclusion/exclusion criteria. 643 patients were included in the analysis, 31 were modulator ineligible(MI). Only 198(31 %) of the total cohort and 7(23 %) of the MI cohort were eligible for participation based on the hypothetical criteria. The most common reason for ineligibility was ppFEV1 ≥90 % followed by clinical instability, complex comorbidity and anticipated inability to adhere to the protocol. We suggest this would be a useful exercise for centres planning to either participate in, or refer subjects into, upcoming trials to undertake for their own cohort. We also make suggestions for protocol designs that optimise the number of patients who are eligible to participate.

Hepatitis B genotypes in Aboriginal and Torres Strait Islander Australians: correlation with clinical course and implications for management.

BACKGROUND: The prevalence of chronic hepatitis B (CHB) in Aboriginal and Torres Strait Islander Australians in Far North Queensland (FNQ) is greater than twice that of the general Australian population. CHB is common in Torres Strait Islanders diagnosed with hepatocellular carcinoma (HCC) - and in Aboriginals with HCC living in the Northern Territory - however, Aboriginals diagnosed with HCC in FNQ very rarely have CHB. The explanation for this apparent disparity is uncertain. AIMS: To determine the HBV genotypes in the FNQ Aboriginal and Torres Strait Islander population and their correlation with clinical phenotype. METHODS: We determined the HBV genotype of Aboriginal and Torres Strait Islander Australians living with CHB in FNQ and correlated this with demographic and clinical findings. RESULTS: 134/197 (68%) enrolled individuals had a sufficient viral load for genotyping. All 40 people with HBV/D genotype had Aboriginal heritage, whereas 85/93 (91%) with HBV/C had Torres Strait Islander heritage (P < 0.0001). Individuals with HBV/D were younger than those with HBV/C (median (interquartile range) age: 43 (39-48) vs 53 (42-66) years, P = 0.0002). However, they were less likely to be HBeAg positive (1/40 (3%) vs 23/93 (25%), P = 0.001). All three HCCs developed in Torres Strait Islanders; two-thirds were infected with HBV/C14; genotyping was not possible in the other individual. All 10 diagnoses of cirrhosis occurred in Torres Strait Islanders, 6/10 were infected with HBV/C14, genotyping was not possible in the other four individuals. CONCLUSIONS: HBV genotypes in Aboriginal and Torres Strait Islander Australians in FNQ differ markedly, which could explain the significant differences in the clinical phenotype in the two populations and might be used to inform cost-effective CHB care in the region.

A discrete choice experiment to quantify the influence of trial features on the decision to participate in cystic fibrosis trials.

BACKGROUND: Patient-centred trial design optimises recruitment and retention, reduces trial failure rates and increases the diversity of trial cohorts. This allows safe and effective treatments to reach clinic more quickly. To achieve this, patients' views must be incorporated into trial design. METHODS: A discrete choice experiment was used to quantify preferences of pwCF for trials features; medicine type, trial location, stipend, washout, drug access on trial completion and trial design. Respondents were presented pairs of hypothetical trial scenarios with different level combinations assigned through experimental design. Respondents were asked to pick their preferred option or decline both. The cross-sectional data were explored using a Random Parameters Logit model. RESULTS: We received 207 eligible responses between Oct2020-Jan2021. The strongest influence on the decision to participate was trial location; pwCF favour participation at their usual clinical centre. Greater travel distances made respondents less willing to participate. Post-trial drug access ranked second. pwCF would rather participate in modulator trials than trials of other drugs. In general, pwCF did not favour a washout period, but were more prepared to washout non-modulators than modulators. Stipend provision was not ranked highly, but higher stipends increased intention to participate. Trial design (placebo vs open-label) had minimal influence on the decision to participate. There are complex interactions between placebos and washouts. CONCLUSIONS: We used quantitative methods to systematically elicit preferences of pwCF for clinical trials' features. We explore the relevance of our findings to trial design and delivery in the current CF trials landscape.

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

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

Reduction in abdominal symptoms (CFAbd-Score), faecal M2-pyruvate-kinase and Calprotectin over one year of treatment with Elexacaftor-Tezacaftor-Ivacaftor in people with CF aged ≥12 years - The RECOVER study.

BACKGROUND: RECOVER is a multicentre post-approval study of Elexacaftor/Tezacaftor/Ivacaftor (ETI) in pwCF in Ireland and the UK. The CFAbd-Score is the first validated CF-specific patient reported outcome measure (PROM) focusing on gastrointestinal symptoms; it comprises 28 items in 5 domains. In a preliminary study, we previously reported reductions in abdominal symptoms (AS) in pwCF after 26 weeks of ETI-therapy using the CFAbd-Score. AIM: to assess changes in AS in a second, large cohort and explore novel GI-biomarkers of gut inflammation and cell-proliferation in pwCF over one year of ETI-therapy. METHODS: Participants were recruited as part of the RECOVER study at 8 sites (Ireland&UK). The CFAbd-Score was administered prior to ETI-initiation, and subsequently at 1,2,6 and 12 months on treatment. Faecal M2-pyruvate kinase (M2-PK) and calprotectin (FC) were quantified in samples collected at baseline, 1 and 6 months. RESULTS: 108 CFAbd-Scores and 73 stool samples were collected at baseline. After 12 months of ETI-therapy, total CFAbd-Scores had significantly declined (15.0±1.4→9.8±1.2pts/p<0.001), and so had all its five domains of "pain" (16.9±2.0pts→9.9±1.8pts/p<0.01), "GERD" (14.4±1.8→9.9±1.6/p<0.05), "disorders of bowel movements" (19.2±1.4→14.1±1.5/p<0.01), "appetite" (7.0±1.1→4.6±1.2/p<0.01) and "impaired-QoL" (13.3±1.9→7.5±1.5/p<0.001). Levels of M2-PK and FC significantly decreased during ETI-therapy. DISCUSSION: In-depth analysis of AS with the CFAbd-Score reveals a statistically significant, clinically relevant and sustained improvement with ETI. We attribute this to high sensitivity of the implemented CF-specific PROM, developed and validated following FDA-guidelines. Furthermore, for the first time during ETI-therapy a significant decline in faecal M2-PK, a marker of inflammation and cell-proliferation, was found, in parallel to FC.

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

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

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).

Chronic rhinosinusitis in the era of CFTR modulator therapy.

Chronic rhinosinusitis is a common manifestation of CF that is associated with impaired quality of life and can be difficult to treat. CFTR modulator therapy has resulted in significant improvements in lower respiratory and nutritional outcomes for people with CF however their impact on chronic rhinosinusitis has received less attention. We review the literature in relation to chronic rhinosinusitis in CF and examine the impact of CFTR modulator therapy on symptoms, imaging, endoscopic appearances, and olfactory outcomes in the treatment of chronic rhinosinusitis. While an overall improvement in symptoms, imaging and endoscopic appearances is seen in response to treatment, limited impact is documented on olfaction. Outcome measures employed were heterogenous, limiting comparison of findings. There is a need for well powered prospective real-world studies with standardised outcome measures.

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.

Unsupervised home spirometry is not equivalent to supervised clinic spirometry in children and young people with cystic fibrosis: Results from the CLIMB-CF study.

BACKGROUND: Handheld spirometry allows monitoring of lung function at home, of particular importance during the COVID-19 pandemic. Pediatric studies are unclear on whether values are interchangeable with traditional, clinic-based spirometry. We aimed to assess differences between contemporaneous, home (unsupervised) and clinic (supervised) spirometry and the variability of the former. The accuracy of the commercially available spirometer used in the study was also tested. METHODS: Data from participants in the Clinical Monitoring and Biomarkers to stratify severity and predict outcomes in children with cystic fibrosisc (CLIMB-CF) Study aged ≥ 6 years who had paired (±1 day) clinic and home forced expiratory volume in 1 s (FEV1 ) readings were analyzed. Variability during clinical stability over 6-months was assessed. Four devices from Vitalograph were tested using 1 and 3 L calibration syringes. RESULTS: Sixty-seven participants (median [interquartile range] age 10.7 [7.6-13.9] years) provided home and clinic FEV1 data pairs. The mean (SD) FEV1 % bias was 6.5% [±8.2%]) with wide limits of agreement (-9.6% to +22.7%); 76.2% of participants recorded lower results at home. Coefficient of variation of home FEV1 % during stable periods was 9.9%. Data from the testing of the handheld device used in CLIMB-CF showed a potential underread. CONCLUSION: In children and adolescents, home spirometry using hand-held equipment cannot be used interchangeably with clinic spirometry. Home spirometry is moderately variable during clinical stability. New handheld devices underread, particularly at lower volumes of potential clinical significance for smaller patients; this suggests that supervision does not account fully for the discrepancy. Opportunities should be taken to obtain dual device measurements in clinic, so that trend data from home can be utilized more accurately.

Computed cardiopulmonography and the idealized lung clearance index, iLCI2.5, in early-stage cystic fibrosis.

This study explored the use of computed cardiopulmonography (CCP) to assess lung function in early-stage cystic fibrosis (CF). CCP has two components. The first is a particularly accurate technique for measuring gas exchange. The second is a computational cardiopulmonary model where patient-specific parameters can be estimated from the measurements of gas exchange. Twenty-five participants (14 healthy controls, 11 early-stage CF) were studied with CCP. They were also studied with a standard clinical protocol to measure the lung clearance index (LCI2.5). Ventilation inhomogeneity, as quantified through CCP parameter σlnCl, was significantly greater (P < 0.005) in CF than in controls, and anatomical deadspace relative to predicted functional residual capacity (DS/FRCpred) was significantly more variable (P < 0.002). Participant-specific parameters were used with the CCP model to calculate idealized values for LCI2.5 (iLCI2.5) where extrapulmonary influences on the LCI2.5, such as breathing pattern, had all been standardized. Both LCI2.5 and iLCI2.5 distinguished clearly between CF and control participants. LCI2.5 values were mostly higher than iLCI2.5 values in a manner dependent on the participant's respiratory rate (r = 0.46, P < 0.05). The within-participant reproducibility for iLCI2.5 appeared better than for LCI2.5, but this did not reach statistical significance (F ratio = 2.2, P = 0.056). Both a sensitivity analysis on iLCI2.5 and a regression analysis on LCI2.5 revealed that these depended primarily on an interactive term between CCP parameters of the form σlnCL*(DS/FRC). In conclusion, the LCI2.5 (or iLCI2.5) probably reflects an amalgam of different underlying lung changes in early-stage CF that would require a multiparameter approach, such as potentially CCP, to resolve.NEW & NOTEWORTHY Computed cardiopulmonography is a new technique comprising a highly accurate sensor for measuring respiratory gas exchange coupled with a cardiopulmonary model that is used to identify a set of patient-specific characteristics of the lung. Here, we show that this technique can improve on a standard clinical approach for lung function testing in cystic fibrosis. Most particularly, an approach incorporating multiple model parameters can potentially separate different aspects of pathological change in this disease.

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).