Lumacaftor/ivacaftor in patients with cystic fibrosis and advanced lung disease homozygous for F508del-CFTR

Use of CFTR modulators in special populations, part 2: Severe lung disease

Safety and efficacy data surrounding cystic fibrosis transmembrane regulator (CFTR) modulator administration for people with CF (pwCF) and severe lung disease elect has remained unclear as a result of exclusion from key trials. A scoping review of English language articles from the period of 1 January 2012, to 31 July 2023 was conducted utilizing PubMed and EmBase databases with the following terms: "severe lung disease" OR "advanced lung disease" AND "ivacaftor OR lumacaftor OR tezacaftor OR elexacaftor"; "cystic fibrosis transmembrane conductance regulator" AND "off label drug use." Search results were reviewed by title and abstract for relevance. Twenty articles specific to CFTR modulator use in the setting of severe lung disease were included for review, with few specific to pediatric-aged pwCF. PwCF and severe lung disease experienced significant improvement in pulmonary function, body weight, number of IV antibiotic days, and quality of life. A few studies reported a transient decline in pulmonary function among pwCF shortly after LUM/IVA initiation. However, preemptive reductions in the dose of LUM/IVA may mitigate this reaction. ELE/TEZ/IVA utilization in pwCF and severe lung disease appears to be devoid of the transient decline in pulmonary function observed with LUM/IVA while providing the same clinical benefit. Current available data regarding use of CFTR modulators in pwCF and severe lung disease is reassuring; however, there remains a lack data regarding outcomes among the pediatric population including long-term outcomes. Therefore, treatment decisions should be individualized and coproduced.

Real-life experience with a generic formulation of lumacaftor-ivacaftor in patients with cystic fibrosis homozygous for the Phe508del CFTR mutation

INTRODUCTION

Cystic fibrosis (CF) is the most frequent recessive autosomal disorder in the Caucasian population. It is caused by mutations that result in a deficient or dysfunctional cystic fibrosis transmembrane conductance regulator (CFTR) protein activity. Among CFTR modulators, potentiator compounds increase channel opening, whereas corrector compounds increase CFTR quantity in the cell surface.

OBJECTIVE

To report real-life effects of a generic formulation of lumacaftor-ivacaftor use in patients with CF homozygous for the Phe508del CFTR mutation.

PATIENTS AND METHODS

Clinical variables (body mass index [BMI], pulmonary exacerbations, sweat test, and pulmonary function) were analyzed in 30 CF patients homozygous for the Phe508del CFTR mutation, treated with lumacaftor-ivacaftor for 12 months, at the Respiratory Center of Hospital de Niños Ricardo Gutiérrez. These clinical variables were compared with those before the use of modulators.

RESULTS

A total of 30 patients with CF homozygous for the Phe508del CFTR mutation receiving lumacaftor-ivacaftor therapy were included in this study. The median (interquartile range [IQR]) age at the start of treatment was 10.79 (7.08-14.05) years. Nineteen patients were male. Before treatment, median (IQR) sweat chloride concentration was 80 (72-92) mEq/L, and it had decreased to 74 (68-78) mEq/L (p = .05) 12 months after treatment. Median (IQR) BMI z-score improved from -0.33 (-0.86 to 0.21) to -0.13 (-0.66 to 0.54) (p = .003). A spirometry was performed in 28 of 30 patients. Median (IQR) ppFEV1 was 83.5 (71-91) before treatment and 86.5 (67-103) after treatment (p = .38), 73.3% of patients referred decreased sputum production and 40% reported improvement in their dyspnea at 12 months. Severe pulmonary exacerbations significantly decreased from 60% in the year before treatment, to 30% at 12 months after treatment (p = .037); 13 patients showed an improvement in their exacerbation rates, 2 showed an increased rate, and 15 showed no change.

CONCLUSIONS

The use of a generic formulation of lumacaftor-ivacaftor in patients homozygous for the Phe508del CFTR mutation was associated with improvement in nutritional status and respiratory symptoms, and a significant reduction in severe pulmonary exacerbations.

Long-term clinical outcomes of elexacaftor/tezacaftor/ivacaftor therapy in adults with cystic fibrosis and advanced pulmonary disease

BACKGROUND

The combination of cystic fibrosis transmembrane conductance regulator (CFTR) modulators elexacaftor, tezacaftor and ivacaftor (ELX/TEZ/IVA) has been approved for treatment of cystic fibrosis (CF) patients (pwCF) homozygous and heterozygous for Phe508del. We aim to assess the long-term effects of ELX/TEZ/IVA therapy on clinical outcomes in severe pwCF.

METHODS

Lung function, pulmonary exacerbation (PEx), sweat chloride concentration, body mass index (BMI) and the respiratory domain of the cystic fibrosis questionnaire-revised (CFQ-R RD) were prospectively evaluated in a cohort of pwCF who were candidates for inclusion in a compassionate program of ELX/TEZ/IVA therapy. All procedures were performed at baseline and then at 12 and 24 months after initiation of modulator therapy. The number of PExs in the year before the study enrollment was collected from our records.

RESULTS

Thirty-six adult pwCF (median age 36.7 years; BMI 19.8 kg/m2; FEV1 36.5% predicted) were recruited from 2019. At 12 and 24 months after initiation, the absolute change in ppFEV1 (percent predicted forced expiratory volume in 1 s) from baseline was +12.5% (p < 0.0001) and +13% (p < 0.0001), respectively. A median of 4.0 exacerbations per patient was reported in the preceding year, while the median number of PExs was 0.0 and 1.0 after 12 and 24 months, respectively, of modulator therapy (both p < 0.0001). After 12 and 24 months of ELX/TEZ/IVA therapy, the CFQ-R RD score improved by 22.4 points (p < 0.0001) and 16.7 points (p < 0.0001), and sweat chloride levels decreased by 65.5 mmol/L (p < 0.0001) and 60 mmol/L (p < 0.0001), respectively. BMI significantly increased.

CONCLUSIONS

Long-term ELX/TEZ/IVA combination therapy markedly impacts the clinical status of patients with severe CF, showing a sustained improvement in lung function and PEx rate.

Human epididymis protein 4 (HE4) plasma concentration inversely correlates with the improvement of cystic fibrosis lung disease in p.Phe508del-CFTR homozygous cases treated with the CFTR modulator lumacaftor/ivacaftor combination

BACKGROUND

We previously documented that elevated HE4 plasma concentration decreased in people with CF (pwCF) bearing the p.Gly551Asp-CFTR variant in response to CFTR modulator (CFTRm) ivacaftor (IVA), and this level was inversely correlated with the FEV1% predicted values (ppFEV1). Although the effectiveness of lumacaftor (LUM)/IVA in pwCF homozygous for the p.Phe508del-CFTR variant has been evaluated, plasma biomarkers were not used to monitor treatment efficacy thus far.

METHODS

Plasma HE4 concentration was examined in 68 pwCF drawn from the PROSPECT study who were homozygous for the p.Phe508del-CFTR variant before treatment and at 1, 3, 6 and 12 months after administration of LUM/IVA therapy. Plasma HE4 was correlated with ppFEV1 using their absolute and delta values. The discriminatory power of delta HE4 was evaluated for the detection of lung function improvements based on ROC-AUC analysis and multiple regression test.

RESULTS

HE4 plasma concentration was significantly reduced below baseline following LUM/IVA administration during the entire study period. The mean change of ppFEV1 was 2.6% (95% CI, 0.6 to 4.5) by 6 months of therapy in this sub-cohort. A significant inverse correlation between delta values of HE4 and ppFEV1 was observed especially in children with CF (r=-0.7053; p<0.0001). Delta HE4 predicted a 2.6% mean change in ppFEV1 (AUC: 0.7898 [95% CI 0.6823-0.8972]; P < 0.0001) at a cut-off value of -10.7 pmol/L. Moreover, delta HE4 independently represented the likelihood of being a responder with ≥ 5% delta ppFEV1 at 6 months (OR: 0.89, 95% CI: 0.82-0.95; P = 0.001).

CONCLUSIONS

Plasma HE4 level negatively correlates with lung function improvement assessed by ppFEV1 in pwCF undergoing LUM/IVA CFTRm treatment.

CFTR Modulators: Current Status and Evolving Knowledge

In the past decade, the medical management of people with cystic fibrosis (pwCF) has changed with the development of small molecules that partially restore the function of the defective CF transmembrane conductance regulator (CFTR) protein and are called CFTR modulators. Ivacaftor (IVA), a CFTR potentiator with a large effect on epithelial ion transport, was the first modulator approved in pwCF carrying gating mutations. Because IVA was unable to restore sufficient CFTR function in pwCF with other mutations, two CFTR correctors (lumacaftor and tezacaftor) were developed and used in combination with IVA in pwCF homozygous for F508del, the most common CFTR variant. However, LUM/IVA and TEZ/IVA were only moderately effective in F508del homozygous pwCF and had no efficacy in those with F508del and minimal function mutations. Elexacaftor, a second-generation corrector, was thus developed and combined to tezacaftor and ivacaftor (ELX/TEZ/IVA) to target pwCF with at least one F508del variant, corresponding to approximately 85% of pwCF. Both IVA and ELX/TEZ/IVA are considered highly effective modulator therapies (HEMTs) in eligible pwCF and are now approved for nearly 90% of the CF population over 6 years of age. HEMTs are responsible for rapid improvement in respiratory manifestations, including improvement in symptoms and lung function, and reduction in the rate of pulmonary exacerbations. The impact of HEMT on extrapulmonary manifestations of CF is less well established, although significant weight gain and improvement in quality of life have been demonstrated. Recent clinical trials and real-world studies suggest that benefits of HEMT could even prove greater when used earlier in life (i.e., in younger children and infants). This article shortly reviews the past 10 years of development and use of CFTR modulators. Effects of HEMT on extrapulmonary manifestations and on CF demographics are also discussed.

Effects of Lumacaftor-Ivacaftor on Airway Microbiota-Mycobiota and Inflammation in Patients with Cystic Fibrosis Appear To Be Linked to Pseudomonas aeruginosa Chronic Colonization

The management of cystic fibrosis has been transformed recently by the advent of CFTR modulators, including lumacaftor-ivacaftor. However, the effects of such therapies on the airway ecosystem, particularly on the microbiota-mycobiota and local inflammation, which are involved in the evolution of pulmonary damage, are unclear.

Design of Crotoxin-Based Peptides with Potentiator Activity Targeting the ΔF508NBD1 Cystic Fibrosis Transmembrane Conductance Regulator

We have previously shown that the CBb subunit of crotoxin, a β-neurotoxin with phospholipase A₂ (PLA₂) activity, targets the human ΔF508CFTR chloride channel implicated in cystic fibrosis (CF). By direct binding to the nucleotide binding domain 1 (NBD1) of ΔF508CFTR, this neurotoxic PLA₂ acts as a potentiator increasing chloride channel current and corrects the trafficking defect of misfolded ΔF508CFTR inside the cell. Here, for a therapeutics development of new anti-cystic fibrosis agents, we use a structure-based in silico approach to design peptides mimicking the CBb-ΔF508NBD1 interface. Combining biophysical and electrophysiological methods, we identify several peptides that interact with the ΔF508NBD1 domain and reveal their effects as potentiators on phosphorylated ΔF508CFTR. Moreover, protein-peptide interactions and electrophysiological studies allowed us to identify key residues of ΔF508NBD1 governing the interactions with the novel potentiators. The designed peptides bind to the same region as CBb phospholipase A₂ on ΔF508NBD1 and potentiate chloride channel activity. Certain peptides also show an additive effect towards the clinically approved VX-770 potentiator. The identified CF therapeutics peptides represent a novel class of CFTR potentiators and illustrate a strategy leading to reproducing the effect of specific protein-protein interactions.

Nutritional impact of CFTR modulators in children with cystic fibrosis

Background

Nutritional status is a major prognostic factor for breathing and the survival of patients with cystic fibrosis (CF). Since 2012, the development of CFTR modulators has considerably transformed the outcome of this disease. Indeed, both lung function and body mass index are improved by CFTR modulators, such as Lumacaftor/Ivacaftor. However, few data exist regarding the outcome of nutritional intakes under Lumacaftor/Ivacaftor.

Methods

We conducted a prospective single-center study in children with CF treated with Lumacaftor/Ivacaftor to evaluate their nutritional intake before and after treatment.

Results

Thirty-four children were included in this study, with a median age of 12.4 years [11.9; 14.7]. There was no significant improvement in weight, height or BMI. Patients' total energy intake was not significantly changed with Lumacaftor/Ivacaftor, while carbohydrate intakes decreased significantly. We found that blood levels of vitamin E and Selenium were significantly increased under Lumacaftor/Ivacaftor, without a significant increase in supplementation. In patients with a BMI Z-score < 0 at treatment initiation, there was a significant improvement in weight and BMI Z-score, while TEI and carbohydrate intakes were significantly lower.

Conclusion

We showed that treatment with Lumacaftor/Ivacaftor improved the nutritional status of patients without necessarily being associated with an increase in nutritional intake. Although these data need to be confirmed in larger cohorts, they support the hypothesis that weight gain under modulators is multifactorial, and may be related to a decrease in energy expenditure or an improvement in absorption.

Brazilian guidelines for the pharmacological treatment of the pulmonary symptoms of cystic fibrosis. Official document of the Sociedade Brasileira de Pneumologia e Tisiologia (SBPT, Brazilian Thoracic Association)

Cystic fibrosis (CF) is a genetic disease that results in dysfunction of the CF transmembrane conductance regulator (CFTR) protein, which is a chloride and bicarbonate channel expressed in the apical portion of epithelial cells of various organs. Dysfunction of that protein results in diverse clinical manifestations, primarily involving the respiratory and gastrointestinal systems, impairing quality of life and reducing life expectancy. Although CF is still an incurable pathology, the therapeutic and prognostic perspectives are now totally different and much more favorable. The purpose of these guidelines is to define evidence-based recommendations regarding the use of pharmacological agents in the treatment of the pulmonary symptoms of CF in Brazil. Questions in the Patients of interest, Intervention to be studied, Comparison of interventions, and Outcome of interest (PICO) format were employed to address aspects related to the use of modulators of this protein (ivacaftor, lumacaftor+ivacaftor, and tezacaftor+ivacaftor), use of dornase alfa, eradication therapy and chronic suppression of Pseudomonas aeruginosa, and eradication of methicillin-resistant Staphylococcus aureus and Burkholderia cepacia complex. To formulate the PICO questions, a group of Brazilian specialists was assembled and a systematic review was carried out on the themes, with meta-analysis when applicable. The results obtained were analyzed in terms of the strength of the evidence compiled, the recommendations being devised by employing the GRADE approach. We believe that these guidelines represent a major advance to be incorporated into the approach to patients with CF, mainly aiming to favor the management of the disease, and could become an auxiliary tool in the definition of public policies related to CF.

Modifier Factors of Cystic Fibrosis Phenotypes: A Focus on Modifier Genes

Although cystic fibrosis (CF) is recognized as a monogenic disease, due to variants within the CFTR (Cystic Fibrosis Transmembrane Regulator) gene, an extreme clinical heterogeneity is described among people with CF (pwCF). Apart from the exocrine pancreatic status, most studies agree that there is little association between CFTR variants and disease phenotypes. Environmental factors have been shown to contribute to this heterogeneity, accounting for almost 50% of the variability of the lung function of pwCF. Nevertheless, pwCF with similar CFTR variants and sharing the same environment (such as in siblings) may have highly variable clinical manifestations not explained by CFTR variants, and only partly explained by environmental factors. It is recognized that genetic variants located outside the CFTR locus, named "modifier genes", influence the clinical expression of the disease. This short review discusses the latest studies that have described modifier factors associated with the various CF phenotypes as well as the response to the recent CFTR modulator therapies.

Gene therapy for cystic fibrosis: Challenges and prospects

Cystic fibrosis (CF) is a life-threatening autosomal-recessive disease caused by mutations in a single gene encoding cystic fibrosis transmembrane conductance regulator (CFTR). CF effects multiple organs, and lung disease is the primary cause of mortality. The median age at death from CF is in the early forties. CF was one of the first diseases to be considered for gene therapy, and efforts focused on treating CF lung disease began shortly after the CFTR gene was identified in 1989. However, despite the quickly established proof-of-concept for CFTR gene transfer in vitro and in clinical trials in 1990s, to date, 36 CF gene therapy clinical trials involving ∼600 patients with CF have yet to achieve their desired outcomes. The long journey to pursue gene therapy as a cure for CF encountered more difficulties than originally anticipated, but immense progress has been made in the past decade in the developments of next generation airway transduction viral vectors and CF animal models that reproduced human CF disease phenotypes. In this review, we look back at the history for the lessons learned from previous clinical trials and summarize the recent advances in the research for CF gene therapy, including the emerging CRISPR-based gene editing strategies. We also discuss the airway transduction vectors, large animal CF models, the complexity of CF pathogenesis and heterogeneity of CFTR expression in airway epithelium, which are the major challenges to the implementation of a successful CF gene therapy, and highlight the future opportunities and prospects.

CFTR Modulators in People with Cystic Fibrosis: Real-World Evidence in France

Cystic fibrosis (CF) is a rare genetic multisystemic disease, the manifestations of which are due to mutations in the gene encoding the CF transmembrane conductance regulator (CFTR) protein and can lead to respiratory insufficiency and premature death. CFTR modulators, which were developed in the past decade, partially restore CFTR protein function. Their clinical efficacy has been demonstrated in phase 3 clinical trials, particularly in terms of lung function and pulmonary exacerbations, nutritional status, and quality of life in people with gating mutations (ivacaftor), homozygous for the F508del mutation (lumacaftor/ivacaftor and tezacaftor/ivacaftor), and in those with at least one F508del mutation (elexacaftor/tezacaftor/ivacaftor). However, many questions remain regarding their long-term safety and effectiveness, particularly in patients with advanced lung disease, liver disease, renal insufficiency, or problematic bacterial colonization. The impact of CFTR modulators on other important outcomes such as concurrent treatments, lung transplantation, chest imaging, or pregnancies also warrants further investigation. The French CF Reference Network includes 47 CF centers that contribute patient data to the comprehensive French CF Registry and have conducted nationwide real-world studies on CFTR modulators. This review seeks to summarize the results of these real-world studies and examine their findings against those of randomized control trials.

CFTR Modulator Therapies: Potential Impact on Airway Infections in Cystic Fibrosis

Cystic Fibrosis (CF) is an autosomal recessive disease caused by mutations in the gene encoding for the Cystic Fibrosis Transmembrane conductance Regulator (CFTR) protein, expressed on the apical surface of epithelial cells. CFTR absence/dysfunction results in ion imbalance and airway surface dehydration that severely compromise the CF airway microenvironment, increasing infection susceptibility. Recently, novel therapies aimed at correcting the basic CFTR defect have become available, leading to substantial clinical improvement of CF patients. The restoration or increase of CFTR function affects the airway microenvironment, improving local defence mechanisms. CFTR modulator drugs might therefore affect the development of chronic airway infections and/or improve the status of existing infections in CF. Thus far, however, the full extent of these effects of CFTR-modulators, especially in the long-term remains still unknown. This review aims to provide an overview of current evidence on the potential impact of CFTR modulators on airway infections in CF. Their role in affecting CF microbiology, the susceptibility to infections as well as the potential efficacy of their use in preventing/decreasing the development of chronic lung infections and the recurrent acute exacerbations in CF will be critically analysed.

Cystic fibrosis: candidate selection and impact of the cystic fibrosis transmembrane conductance regulator therapy

PURPOSE OF REVIEW

Over the past decade, the development of highly effective cystic fibrosis (CF) transmembrane conductance regulator (CFTR) modulators has dramatically ameliorated the manifestations of CF for most patients. Perhaps most importantly, CFTR modulators impact the development and progression of advanced lung disease (ALD) and are changing the CF population accessing lung transplant.

RECENT FINDINGS

A recent phase 3 trial of elexacaftor/tezacaftor/ivacaftor (ETI) demonstrated efficacy for individuals with at least one copy of the most common CF mutation, F508del. Studies of CFTR modulator therapy in patients with ALD have demonstrated similar improvements in lung function, nutrition, and pulmonary exacerbation frequency as seen in individuals with higher lung function. Due to improvements with ETI, rates of lung transplant for CF have declined and individuals are achieving stability in lung function. Nevertheless, the Cystic Fibrosis Foundation guidelines for lung transplant referral should be used to guide referral decisions for all individuals with CF, including those on CFTR modulator therapy, to allow remediation of modifiable barriers to transplant. ETI may be used in the posttransplant setting but for selected individuals and with close monitoring.

SUMMARY

Increasing access to highly effective CFTR modulators has changed the trajectory of lung disease in CF for many, but not all, individuals and there remain individuals who cannot access therapy or whose mutations do not respond to modulators. Lung transplant remains an important treatment option for individuals with advanced CF lung disease. Increasing attention will be required to optimize decisions of when to list for transplant.

Elexacaftor/Tezacaftor/Ivacaftor in Patients with Cystic Fibrosis Homozygous for the F508del Mutation and Advanced Lung Disease: A 48-Week Observational Study

Background: Elexacaftor/tezacaftor/ivacaftor (ETI) is the newest cystic fibrosis transmembrane conductance regulator (CFTR) modulator drug approved for the treatment of patients with cystic fibrosis (pwCF) aged ≥6 years with at least one copy of the F508del mutation (F) in the CFTR gene or another mutation that is responsive to treatment with ETI. This study determined the effectiveness and safety of ETI in a cohort of severely affected pwCF with an F/F genotype. Methods: Retrospective observational study in F/F pwCF treated for 48 weeks, enrolled in an ETI managed access program available to subjects with advanced lung disease (ppFEV₁ < 40). Twenty-six patients from three centres were included. The main outcomes included lung function, sweat chloride concentration (SCC), nutrition, frequency of pulmonary exacerbations (PEx), CFQ-R, and safety. Results: ppFEV₁ improved by 12.06 (95%CI 8.54, 15.57) from baseline after 4 weeks of treatment with ETI, 15.32 (11.3, 19.34) after 24 weeks, and 14.48 (10.64, 18.32) after 48 weeks. The increase in FEV₁ was accompanied by a decrease in SCC, improvement of BMI, and noticeable reduction in PEx. An overall good safety profile was observed. Conclusions: In F/F pwCF with advanced lung disease with an F/F genotype, ETI was safe and associated with clinical improvement.

Factors Predisposing the Response to Lumacaftor/Ivacaftor in People with Cystic Fibrosis

Lumacaftor/ivacaftor (LUMA-IVA) therapy is prescribed to people with cystic fibrosis (pwCF) homozygous for the Phe508del-CFTR variant to restore CFTR protein function. There is, however, large inter-individual variability in treatment response. Here, we seek to identify clinical and/or genetic factors that may modulate the response to this CFTR modulator therapy. A total of 765 pwCF older than 12 years under LUMA-IVA therapy and with lung function and nutritional measurements available before and after treatment initiation were included. Response to treatment was determined by the change in lung function and nutritional status, from baseline and over the first two years after initiation, and it was assessed by weighted generalized estimating equation models. Gains in lung function and nutritional status were observed after 6 months of treatment (on average 2.11 ± 7.81% for percent predicted FEV₁ and 0.44 ± 0.77 kg/m² for BMI) and sustained over the 2 years. We observed that the more severe patients gained the most in lung function and nutritional status. While females started with a nutritional status more impaired than males, they had a larger response and regained BMI Z-score values similar to men after 2 years of treatment. We observed no association between variants in solute carrier (SLC) genes and the respiratory function response to LUMA-IVA, but the SLC6A14 rs12839137 variant was associated with the nutritional response. Further investigations, including other genomic regions, will be needed to fully explore the inter-individual variability of the response to LUMA-IVA.

CFTR Modulator Therapy and Its Impact on Lung Transplantation in Cystic Fibrosis

Cystic fibrosis (CF) is the most common autosomal recessive disorder in Caucasian people and is caused by mutations in the gene encoding for the CF transmembrane conductance regulator (CFTR) protein. It is a multisystem disorder; however, CF lung disease causes most of its morbidity and mortality. Although survival for CF has improved over time due to a multifaceted symptomatic management approach, CF remains a life-limiting disease. For individuals with progressive advanced CF lung disease (ACFLD), lung transplantation is considered the ultimate treatment option if compatible with goals of care. Since 2012, newer drugs, called CFTR modulators, have gradually become available, revolutionizing CF care, as these small-molecule drugs target the underlying defect in CF that causes decreased CFTR protein synthesis, function, or stability. Because of their extremely high efficacy and overall respectable tolerability, CFTR modulator drugs have already proven to have a substantial positive impact on the lives of individuals with CF. Individuals with ACFLD have generally been excluded from initial clinical trials. Now, however, these drugs are being used in clinical practice in selected individuals with ACFLD, showing promising results, although randomized controlled trial data for CFTR modulators in this subgroup of patients are lacking. Such data need to be gathered, ideally in randomized controlled trials including patients with ACFLD. Furthermore, the efficacy and tolerability of the newer modulator therapies in individuals with ACFLD need to be monitored, and their impact on lung disease progression and the need for lung transplantation as the ultimate therapy call for an objective evaluation in larger patient cohorts. As of today, guidelines for referral and listing of lung transplant candidates with CF have not incorporated the status of the new CFTR modulator therapies in the referral and listing process. The purpose of this review article, therefore, is threefold: first, to describe the effects of new therapies, with a focus on the subgroup of individuals with ACFLD; second, to provide an update on the recent outcomes after lung transplantation for individuals with CF; and third, to discuss the referral, evaluation, and timing for lung transplantation as the ultimate therapeutic option in view of the new treatments available in CF.

Delayed hepatic necrosis in a cystic fibrosis patient taking Elexacaftor/Tezacaftor/Ivacaftor (Kaftrio)

The introduction of Cystic Fibrosis Trans Regulatory modulator (CFTRm) drugs has seen a transformation in Cystic Fibrosis (CF) treatment. This has led to a significant improvement in lung function and quality of life with the potential for a real impact on life expectancy.

Transient mild to moderate hepatic transaminitis is a well-known side effect of CFTRm drugs, which often improves on cessation and may not recur following the re-institution of the drug. We describe a case of transaminitis developing nine months after the initiation of Kaftrio, which progressed to liver necrosis despite stopping Kaftrio and took many months to resolve.

The patient had experienced significant improvement in lung function and overall health while on Kaftrio and deteriorated when it was stopped. He was keen to restart; however, Kaftrio was not reinstated due to the potential risk of acute liver failure.

Effects of Lumacaftor-Ivacaftor on Lung Clearance Index, Magnetic Resonance Imaging, and Airway Microbiome in Phe508del Homozygous Patients with Cystic Fibrosis

Rationale: Previous studies showed that lumacaftor-ivacaftor therapy results in partial rescue of CFTR (cystic fibrosis [CF] transmembrane conductance regulator) activity and a moderate improvement of spirometry in Phe508del homozygous patients with CF. However, the effects of lumacaftor-ivacaftor on lung clearance index (LCI), lung morphology and perfusion detected by chest magnetic resonance imaging (MRI), and effects on the airway microbiome and inflammation remain unknown. Objectives: To investigate the effects of lumacaftor-ivacaftor on LCI, lung MRI scores, and airway microbiome and inflammation. Methods: In this prospective observational study we assessed clinical outcomes including spirometry and body mass index, LCI, lung MRI scores, sputum microbiome, and proinflammatory cytokines in 30 Phe508del homozygous patients with CF 12 years and older before and 8-16 weeks after initiation of lumacaftor-ivacaftor therapy. Results: Lumacaftor-ivacaftor had no effects on forced expiratory volume in 1 second (FEV₁% predicted) (1.7%; 95% confidence interval [CI], -1.0% to 4.3%; P = 0.211) but improved LCI (-1.6; 95% CI, -2.6 to -0.5; P < 0.01) and MRI morphology (-1.3; 95% CI, -2.3 to -0.3; P < 0.05) and perfusion score (-1.2; 95% CI, -2.3 to -0.2; P < 0.05) in our study cohort. Furthermore, lumacaftor-ivacaftor decreased the total bacterial load (-1.8; 95% CI, -3.3 to -0.34; P < 0.05) and increased the Shannon diversity of the airway microbiome (0.4; 95% CI, 0.1 to 0.8; P < 0.05), and reduced IL-1β (interleukin-1β) concentration (median change, -324.2 pg/ml; 95% CI, -938.7 to 290.4 pg/ml; P < 0.05) in sputum of Phe508del homozygous patients. Conclusions: This study shows that lumacaftor-ivacaftor has beneficial effects on lung ventilation, morphology, and perfusion, as well as on the airway microbiome and inflammation in Phe508del homozygous patients. Our results suggest that LCI and MRI may be more sensitive than FEV₁% predicted to detect response to CFTR modulator therapy in patients with chronic CF lung disease. Clinical trial registered with ClinicalTrials.gov (NCT02807415).

Validation of nasospheroids to assay CFTR functionality and modulator responses in cystic fibrosis

The availability of a simple, robust and non-invasive in vitro airway model would be useful to study the functionality of the cystic fibrosis transmembrane regulator (CFTR) protein and to personalize modulator therapy for cystic fibrosis (CF) patients. Our aim was to validate a CFTR functional study using nasospheroids, a patient-derived nasal cell 3D-culture. We performed live-cell experiments in nasospheroids obtained from wild-type individuals and CF patients with different genotypes and phenotypes. We extended the existing method and expanded the analysis to upgrade measurements of CFTR activity using forskolin-induced shrinking. We also tested modulator drugs in CF samples. Immobilizing suspended-nasospheroids provided a high number of samples for live-cell imaging. The diversity observed in basal sizes of nasospheroids did not affect the functional analysis of CFTR. Statistical analysis with our method was simple, making this protocol easy to reproduce. Moreover, we implemented the measurement of inner fluid reservoir areas to further differentiate CFTR functionality. In summary, this rapid methodology is helpful to analyse response to modulators in CF samples to allow individualized treatment for CF patients.

Clostridioides difficile colonization and infection in a cohort of Australian adults with cystic fibrosis

BACKGROUND

Little is known about Clostridioides difficile infection (CDI) in patients with cystic fibrosis (CF). The aim of this study was to investigate the prevalence, molecular epidemiology and risk factors for CDI in asymptomatic and symptomatic adults with CF in Western Australia.

METHODS

Faecal samples from symptomatic and asymptomatic patients were prospectively collected and tested for the presence of C. difficile by toxigenic culture. Ribotyping was performed by established protocols. Logistic regression analysis was performed to analyse the risk factors for C. difficile colonization and infection. Extensive environmental sampling was performed within the CF clinic in Perth.

RESULTS

The prevalence rates of asymptomatic toxigenic and non-toxigenic C. difficile colonization were 30% (14/46 patients) and 24% (11/46 patients), respectively. Fifteen ribotypes (RTs) of C. difficile were identified, of which non-toxigenic RT 039 was the most common. Among the symptomatic patients, the prevalence of toxigenic CDI was 33% (11/33 patients). Impaired glucose tolerance/diabetes mellitus and duration of intravenous antibiotic use in the past 12 months were significantly associated with increased risk of asymptomatic toxigenic C. difficile carriage and CDI. A trend towards higher CF transmembrane conductance regulator modulator treatment was observed in the CDI group. Extensive environmental sampling showed no evidence of toxigenic C. difficile contamination within the CF clinic.

CONCLUSIONS

A high prevalence of asymptomatic carriage of toxigenic C. difficile was observed in adults with CF, comparable with that observed in the symptomatic CF population. There was no evidence of direct person-to-person transmission.

Lumacaftor/ivacaftor-associated health stabilisation in adults with severe cystic fibrosis

Introduction

Lumacaftor/ivacaftor (LUM/IVA) has been shown to improve clinical outcomes in cystic fibrosis (CF) patients homozygous for Phe508del with forced expiratory volume in 1 s (FEV₁) % pred >40%. We assessed the clinical utility of LUM/IVA in all eligible adult CF patients with FEV₁ % pred <40% treated for at least 1 year under a single-centre managed access programme.

Methods

Following clinical optimisation, eligible patients (n=40) with FEV₁ % pred <40% were commenced on LUM/IVA and monitored for tolerance and clinical outcomes, including health service utilisation, pulmonary function, weight and body composition. 24 patients reached 1 year of treatment by the time of evaluation. Six patients discontinued due to adverse events (five for increased airways reactivity) and three underwent lung transplantation.

Results

In comparison with the year prior to LUM/IVA commencement, significant reductions (median per year) were observed in the treatment year in the number of pulmonary exacerbations requiring hospitalisation (from 3 to 1.5; p=0.0002), hospitalisation days (from 27 to 17; p=0.0002) and intravenous antibiotic (IVAB) usage days (from 45 to 27; p=0.0007). Mean±sd change in FEV₁ % pred was −2.10±1.18% per year in the year prior, with the decline reversed in the year following (+1.45±1.13% per year; p=0.035), although there was significant heterogeneity in individual responses. Mean±sd weight gain at 1 year was 2.5±4.1 kg (p=0.0007), comprising mainly fat mass (mean 2.2 kg). The proportion of patients severely underweight (body mass index <18.5 kg·m⁻²) decreased from 33% at baseline to 13% at 1 year (p=0.003).

Conclusion

This real-world evaluation study demonstrated benefits over several clinical domains (infective exacerbations requiring hospitalisation, IVABs, pulmonary function decline and nutritional parameters) in CF patients with severe lung disease.

In adults with severe cystic fibrosis lung disease, 1 year of treatment with lumacaftor/ivacaftor was associated with reduced infective exacerbations, days of intravenous antibiotics and rate of pulmonary function decline, and improved nutritional statushttps://bit.ly/2I07suR

The effectiveness and value of novel treatments for cystic fibrosis

DISCLOSURES: Funding for this summary was contributed by Arnold Ventures, California Health Care Foundation, Harvard Pilgrim Health Care, and Kaiser Foundation Health Plan to the Institute for Clinical and Economic Review (ICER), an independent organization that evaluates the evidence on the value of health care interventions. ICER's annual policy summit is supported by dues from Aetna, America's Health Insurance Plans, Anthem, Allergan, Alnylam, AstraZeneca, Biogen, Blue Shield of CA, Boehringer-Ingelheim, Cambia Health Services, CVS, Editas, Express Scripts, Genentech/Roche, GlaxoSmithKline, Harvard Pilgrim, Health Care Service Corporation, HealthFirst, Health Partners, Johnson & Johnson (Janssen), Kaiser Permanente, LEO Pharma, Mallinckrodt, Merck, Novartis, National Pharmaceutical Council, Pfizer, Premera, Prime Therapeutics, Regeneron, Sanofi, Spark Therapeutics, and United Healthcare. Seidner, Rind, and Pearson are employed by ICER. Tice reports contracts to his institution, University of California, San Francisco, from ICER during the conduct of this study. Wherry has nothing to disclose.

Real-World Safety of CFTR Modulators in the Treatment of Cystic Fibrosis: A Systematic Review

Cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapies target the underlying cause of cystic fibrosis (CF), and are generally well-tolerated; however, real-world studies indicate the frequency of discontinuation and adverse events (AEs) may be higher than what was observed in clinical trials. The objectives of this systematic review were to summarize real-world AEs reported for market-available CFTR modulators (i.e., ivacaftor (IVA), lumacaftor/ivacaftor (LUM/IVA), tezacaftor/ivacaftor (TEZ/IVA), and elexacaftor/tezacaftor/ivacaftor (ELX/TEZ/IVA)), and to identify ways in which the pharmacist on CF healthcare teams may contribute to mitigating and managing these AEs. The MEDLINE, EMBASE, CINAHL, and Web of Science Core Collection online databases were searched from 2012 to 1 Aug 2020. Full manuscripts or conference abstracts of observational studies, case series, and case reports were eligible for inclusion. The included full manuscripts and conference abstracts comprised of 54 observational studies, 5 case series, and 9 case reports. The types of AEs reported generally aligned with what have been observed in clinical trials. LUM/IVA was associated with a higher frequency of respiratory-related AE and discontinuation in real-world studies. A signal for mental health and neurocognitive AEs was identified with all 4 CFTR modulators. A systematic approach to monitoring for AEs in people with CF on CFTR modulators in the real-world setting is necessary to help better understand potential AEs, as well as patient characteristics that may be associated with higher risk of certain AEs. Pharmacists play a key role in the safe initiation and monitoring of people with CF on CFTR modulator therapies.

A current review of the safety of cystic fibrosis transmembrane conductance regulator modulators

WHAT IS KNOWN AND OBJECTIVE

Treatment with cystic fibrosis transmembrane conductance regulator (CFTR) modulators has led to improved clinical outcomes and an increase in lifespans of cystic fibrosis (CF) patients. As CF patients continue to live longer, they are at risk for developing adverse drug reactions associated with polypharmacy and CFTR modulators.

COMMENT

The authors aim to describe safety concerns of the current combination CFTR modulators, based upon a literature review, including notable safety concerns and recommendations for drug-drug interactions.

WHAT IS NEW AND CONCLUSION

Cystic fibrosis transmembrane conductance regulator agents are generally well tolerated with low discontinuation rates when compared to placebo. Elevations in liver enzymes and drug-drug interactions are the most notable safety concerns. Additionally, lumacaftor/ivacaftor has shown more respiratory-related adverse events and drug-drug interactions compared to elexacaftor/tezacaftor/ivacaftor and tezacaftor/ivacaftor. Postmarketing studies are needed to determine long-term safety concerns.

Patients with cystic fibrosis and advanced lung disease benefit from lumacaftor/ivacaftor treatment

BACKGROUND

Several studies have assessed safety and efficacy outcomes for lumacaftor/ivacaftor therapy. We report on lumacaftor/ivacaftor's impact on lung function, physical performance, and health-related quality of life (HRQOL) in a subpopulation of Danish people with Cystic Fibrosis (CF; PWCF) with advanced pulmonary disease who would not fulfill inclusion criteria for these studies.

METHODS

This follow-up study examined lumacaftor/ivacaftor's effect in a highly selected CF population. Inclusion criteria included low percent predicted forced expiratory volume in one second (ppFEV₁ ), fast deteriorating ppFEV₁ , low body mass index (BMI), and difficult-to-treat infections. Primary endpoints included change in ppFEV₁ slope, cardiopulmonary exercise testing (CPET), and all domains of the Cystic Fibrosis Questionnaire-Revised (CFQ-R). Secondary outcomes included change in ppFEV₁ , BMI Z-score, and sweat chloride concentration.

RESULTS

A total of 21 patients homozygous for the F508del mutation and a median ppFEV₁ of 38.7 were included. We found significant improvements in ppFEV₁ (+4.2 p < .01, +5.8 p < .01, +4.8 p < .01 and +3.8 p = .03 ppFEV₁ after 3, 6, 9, and 12 months of treatment compared to baseline), ppFEV₁ slope (+6.84 ppFEV₁ /year between the year before and the year after treatment initiation; p = .02), and saturation at CPET initiation (+1.4%, p < .02) and termination (+2.6%, p < .01) after 6 months of treatment. Finally, HRQOL improved significantly in all CFQ-R domains except Emotion and Treat.

CONCLUSIONS

Our findings suggest that lumacaftor/ivacaftor reduces lung function decline, improves lung function, physical performance, and HRQOL to a greater extent in PWCF with severe lung disease than previously recognized.

Novel therapeutic approaches for the management of cystic fibrosis

Cystic fibrosis (CF) is a genetic condition characterised by the build-up of thick, sticky mucus that can damage many of the body's organs. It is a life-long disease that results in a shortened life expectancy, often due to the progression of advanced lung disease. Treatment has previously targeted the downstream symptoms such as diminished mucus clearance and recurrent infection. More recently, significant advances have been made in treating the cause of the disease by targeting the faulty gene responsible. Hope for the development of potential therapies lies with ongoing research into new pharmacological agents and gene therapy. This review gives an overview of CF, and summarises the current evidence regarding the disease management and upcoming strategies aimed at treating or potentially curing this condition.

Cystic fibrosis - Ten promising therapeutic approaches in the current era of care

INTRODUCTION

Cystic fibrosis (CF) is a genetic disease affecting multiple organ systems. Research and innovations in novel therapeutic agents and health care delivery have resulted in dramatic improvements in quality of life and survival for people with CF. Despite this, significant disease burden persists for many and this is compounded by disparities in treatment access and care which globally necessitates further work to improve outcomes. Because of the advent of numerous therapies which include gene-targeted modulators in parallel with specialized care delivery models, innovative efforts continue.

AREAS COVERED

In this review, we discuss the available data on investigational agents in clinical development and currently available treatments for CF. We also evaluate approaches to care delivery, consider treatment gaps, and propose future directions for advancement.

EXPERT OPINION

Since the discovery of the CF gene, CFTR modulators have provided a hallmark of success, even though it was thought not previously possible. This has led to reinvigorated efforts and innovations in treatment approaches and care delivery. Numerous challenges remain because of genetic and phenotypic heterogeneity, access issues, and therapeutic costs, but the collaborative approach between stakeholders for continued innovation fuels optimism. Abbreviations: CF cystic fibrosis; CFF Cystic Fibrosis Foundation (USA); CFTR cystic fibrosis transmembrane regulator; CRISPR clustered regularly interspaced short palindromic repeats; COX cyclo oxygenase; FDA US Food and Drug Administration; FEV1% forced expiratory volume in one second % predicted; F508del deletion of phenylalanine (F) in the 508th position (most common mutation); G551D substitution of the amino acid glycine by aspartate at position 551 in the nucleotide binding domain-1 of the CFTR gene; LMIC low- and middle-income country; LTB4 leukotriene B4; MDT multi-disciplinary care team; NO nitric oxide; NSAIDs non-steroidal anti-inflammatory drugs; SLPI secretory leukocyte protease inhibitor.

ENaC regulation by phospholipids and DGK explained through mathematical modeling

Cystic fibrosis is a condition caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR). It is also thought to increase the activity of epithelial sodium channels (ENaC). The altered function of these ion channels is one of the causes of the thick dehydrated mucus that characterizes the disease and is partially responsible for recurrent pulmonary infections and inflammation events that ultimately destroy the lungs of affected subjects. Phosphoinositides are signaling lipids that regulate numerous cellular processes and membrane proteins, including ENaC. Inhibition of diacylglycerol kinase (DGK), an enzyme of the phosphoinositide pathway, reduces ENaC function. We propose a computational analysis that is based on the combination of two existing mathematical models: one representing the dynamics of phosphoinositides and the other explaining how phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) influences ENaC activity and, consequently, airway surface liquid. This integrated model permits, for the first time, a detailed assessment of the intricate interactions between DGK and ENaC and is consistent with available literature data. In particular, the computational approach allows comparisons of two competing hypotheses regarding the regulation of ENaC. The results strongly suggest that the regulation of ENaC is primarily exerted through the control of PI(4,5)P2 production by type-I phosphatidylinositol-4-phosphate 5-kinase (PIP5KI), which in turn is controlled by phosphatidic acid (PA), the product of the DGK reaction.

Tezacaftor/ivacaftor in people with cystic fibrosis who stopped lumacaftor/ivacaftor due to respiratory adverse events

Background:

Increased rates of respiratory adverse events have been observed in people ≥12 years of age with cystic fibrosis homozygous for the Phe508del-CFTR mutation treated with lumacaftor/ivacaftor, particularly in those with percent predicted forced expiratory volume in 1 s (ppFEV₁) of <40%. We evaluated the safety, tolerability, and efficacy of tezacaftor/ivacaftor in people with cystic fibrosis homozygous for Phe508del-CFTR who discontinued lumacaftor/ivacaftor due to treatment-related respiratory signs or symptoms.

Methods:

Participants ≥12 years of age with cystic fibrosis homozygous for Phe508del-CFTR with ppFEV₁ of ≥25% and ≤90% were randomized 1:1 and treated with tezacaftor/ivacaftor or placebo for 56 days.

Results:

Of 97 participants, 94 (96.9%) completed the study. The primary endpoint was incidence of predefined respiratory adverse events of special interest (chest discomfort, dyspnea, respiration abnormal, asthma, bronchial hyperreactivity, bronchospasm, and wheezing): tezacaftor/ivacaftor, 14.0%; placebo, 21.3%. The adverse events were mild or moderate in severity. None were serious or led to treatment interruption or discontinuation. Overall, the discontinuation rate was similar between groups. The mean (SD) ppFEV₁ at baseline was 44.6% (16.1%) with tezacaftor/ivacaftor and 48.0% (18.1%) with placebo. The posterior mean difference in absolute change in ppFEV₁ from baseline to the average value of days 28 and 56 was 2.7 percentage points with tezacaftor/ivacaftor vs placebo.

Conclusions:

Tezacaftor/ivacaftor was generally safe, well tolerated, and efficacious in people ≥12 years of age with cystic fibrosis homozygous for Phe508del-CFTR with ppFEV₁ of ≥25% and ≤90% who previously discontinued lumacaftor/ivacaftor due to treatment-related respiratory signs or symptoms.

Cystic fibrosis transmembrane conductance receptor modulator therapy in cystic fibrosis, an update

PURPOSE OF REVIEW

Cystic fibrosis transmembrane conductance receptor (CFTR) modulators are a new class of drugs that treat the underlying cause of cystic fibrosis. To date, there are four approved medications, which are mutation-specific. Although the number of mutations that respond to these agents is expanding, effective CFTR modulators are not available to all cystic fibrosis patients. The purpose of this article is to review the approved CFTR modulators and discuss the mutations that can be treated with these agents, as well as, review the long-term benefits of modulator therapy.

RECENT FINDINGS

More people with cystic fibrosis can be effectively treated with CFTR modulators. The new, highly effective triple therapy, elexacaftor/tezacaftor/ivacaftor is indicated for more than 90% of patients with cystic fibrosis and ivacaftor is now approved for children as young as 6 months of age with 1 of 30 CFTR mutations. Long-term use of modulator therapy is associated with fewer pulmonary exacerbations, maintenance of lung function, improved weight gain, and quality of life.

SUMMARY

CFTR modulators are the first therapies developed to treat the underlying defect in cystic fibrosis. Their use is associated with preserved lung function and improved health in patients with cystic fibrosis.

Re-imagining cystic fibrosis care: next generation thinking

Cystic fibrosis (CF) is a common multi-system genetically inherited condition, predominately found in individuals of Caucasian decent. Since the identification of the cystic fibrosis (CF) transmembrane conductance regulator (CFTR) gene in 1989, and the subsequent improvement in understanding of CF pathophysiology, significant increases in life-expectancy have followed. Initially this was related to improvements in the management and systems of care for treating the various affected organ systems. These cornerstone treatments are still essential for CF patients born today. However, over the last decade, the major advance has been in therapies that target the resultant genetic defect: the dysfunctional CFTR protein. Small molecule agents that target this dysfunctional protein via a variety of mechanisms have led to lung function improvements, reductions in pulmonary exacerbation rates and increases in weight and quality-of-life indices. As more patients receive these agents earlier and earlier in life, it is likely that general CF care will increasingly pivot around these specific therapies, although it is also likely that effects other than those identified in the initial trials will be discovered and need to be managed. Despite great excitement for modulator therapies, they are unlikely to be suitable or available for all; whether this is due to a lack of availability for specific CFTR mutations, drug-reactions or the health economic set-up in certain countries. Nevertheless, the CF community must be applauded for its ongoing focus on research and development for this life-limiting disease. With time, personalised individualised therapy would ideally be the mainstay of CF care.

Cystic fibrosis in the year 2020: A disease with a new face

The autosomal recessive disease cystic fibrosis (CF) was once untreatable and deadly in childhood, but now most patients survive to adulthood. Many countries have instituted CF newborn screening because early diagnosis improves outcome. CF research has greatly intensified following the discovery of the CF transmembrane conductance regulator (CFTR) gene, which has more than 2000 different mutations. For patients with common mutations like F508del, CFTR modulators are life transforming and may even prevent major complications if started early in childhood. For some patients with rare CFTR mutations, a treatment path still needs to be developed. Conclusion: This review provides a general update on CF, including screening and current and future treatment.

Rectal Organoids Enable Personalized Treatment of Cystic Fibrosis

In vitro drug tests using patient-derived stem cell cultures offer opportunities to individually select efficacious treatments. Here, we provide a study that demonstrates that in vitro drug responses in rectal organoids from individual patients with cystic fibrosis (CF) correlate with changes in two in vivo therapeutic endpoints. We measured individual in vitro efficaciousness using a functional assay in rectum-derived organoids based on forskolin-induced swelling and studied the correlation with in vivo effects. The in vitro organoid responses correlated with both change in pulmonary response and change in sweat chloride concentration. Receiver operating characteristic curves indicated good-to-excellent accuracy of the organoid-based test for defining clinical responses. This study indicates that an in vitro assay using stem cell cultures can prospectively select efficacious treatments for patients and suggests that biobanked stem cell resources can be used to tailor individual treatments in a cost-effective and patient-friendly manner.

The preclinical discovery and development of the combination of ivacaftor + tezacaftor used to treat cystic fibrosis

INTRODUCTION

Cystic Fibrosis (CF) is caused by mutations in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene. The most common mutation, F508del, induces protein misprocessing and loss of CFTR function. The discovery through in vitro studies of the CFTR correctors (i.e. lumacaftor, tezacaftor) that partially rescue the misprocessing of F508del-CFTR with the potentiator ivacaftor is promising in giving an unprecedented clinical benefit in affected patients.

AREAS COVERED

Online databases were searched using key phrases for CF and CFTR modulators. Tezacaftor-ivacaftor treatment has proved to be safer than lumacaftor-ivacaftor, although clinical efficacy is similar. Further clinical efficacy has ensued with the introduction of triple therapy, i.e. applying second-generation correctors, such as VX-569 and VX-445 (elexacaftor) to tezacaftor-ivacaftor. The triple combinations will herald the availability of etiologic therapies for patients for whom no CFTR modulators are currently applied (i.e. F508del/minimal function mutations) and enhance CFTR modulator therapy for patients homozygous for F508del.

EXPERT OPINION

CF patient-derived tissue models are being explored to determine donor-specific response to current approved and future novel CFTR modulators for F508del and other rare mutations. The discovery and validation of biomarkers of CFTR modulation will complement these studies in the long term and in real-life world.

Impact of CFTR modulator use on outcomes in people with severe cystic fibrosis lung disease

Drug compounds that augment the production and activity of the cystic fibrosis (CF) transmembrane regulator (CFTR) have revolutionised CF care. Many adults and some children with CF suffer advanced and severe lung disease or await lung transplantation. While the hope is that these drug compounds will prevent lung damage when started early in life, there is an ongoing need to care for people with advanced lung disease. The focus of this review is the accumulating data from clinical trials and case series regarding the benefits of CFTR modulator therapy in people with advanced pulmonary disease. We address the impact of treatment with ivacaftor, lumacaftor/ivacaftor, tezacaftor/ivacaftor and elexacaftor/tezacaftor/ivacaftor on lung function, pulmonary exacerbations, nutrition and quality of life. Adverse events of the different CFTR modulators, as well as the potential for drug–drug interactions, are discussed.

CFTR modulators are efficacious in improving lung function and exacerbations, even in advanced CF. However, adverse drug reactions and drug interactions are frequent.http://bit.ly/37aN81E

CFTR Modulators: The Changing Face of Cystic Fibrosis in the Era of Precision Medicine

Cystic fibrosis (CF) is a lethal inherited disease caused by mutations in the CF transmembrane conductance regulator (CFTR) gene, which result in impairment of CFTR mRNA and protein expression, function, stability or a combination of these. Although CF leads to multifaceted clinical manifestations, the respiratory disorder represents the major cause of morbidity and mortality of these patients. The life expectancy of CF patients has substantially lengthened due to early diagnosis and improvements in symptomatic therapeutic regimens. Quality of life remains nevertheless limited, as these individuals are subjected to considerable clinical, psychosocial and economic burdens. Since the discovery of the CFTR gene in 1989, tremendous efforts have been made to develop therapies acting more upstream on the pathogenesis cascade, thereby overcoming the underlying dysfunctions caused by CFTR mutations. In this line, the advances in cell-based high-throughput screenings have been facilitating the fast-tracking of CFTR modulators. These modulator drugs have the ability to enhance or even restore the functional expression of specific CF-causing mutations, and they have been classified into five main groups depending on their effects on CFTR mutations: potentiators, correctors, stabilizers, read-through agents, and amplifiers. To date, four CFTR modulators have reached the market, and these pharmaceutical therapies are transforming patients' lives with short- and long-term improvements in clinical outcomes. Such breakthroughs have paved the way for the development of novel CFTR modulators, which are currently under experimental and clinical investigations. Furthermore, recent insights into the CFTR structure will be useful for the rational design of next-generation modulator drugs. This review aims to provide a summary of recent developments in CFTR-directed therapeutics. Barriers and future directions are also discussed in order to optimize treatment adherence, identify feasible and sustainable solutions for equitable access to these therapies, and continue to expand the pipeline of novel modulators that may result in effective precision medicine for all individuals with CF.

Tezacaftor and ivacaftor for the treatment of cystic fibrosis

Introduction: Cystic fibrosis (CF) is a complex, multi-system, genetic disease affecting over 70,000 people worldwide. The underlying defect is a mutation in the CFTR gene. Dysfunctional CFTR protein results in abnormal anion movement across epithelial membranes in affected organs. There has been a paradigm shift in CF treatment over the last decade with the advent of CFTR modulation, treatments which target this underlying genetic defect and have the potential to change the course of CF clinical disease.Areas covered: Available CFTR modulators in current clinical practice are reviewed in this article, with a direct comparison and summary of relevant pivotal clinical trials. The approval of ivacaftor and subsequent development of lumacaftor and tezacaftor dual combinations represents an exciting development in CF management in recent years.Expert opinion: Tezacaftor/ivacaftor (tez/iva) appears to have a more favorable adverse event and drug-drug interaction profile than lumacaftor/ivacaftor. Tez/iva has been approved, alongside Phe508del, for a large number of 'residual function' CFTR mutations, with some based on response to in vitro culture. Dual therapy with tez/iva has paved the way for triple CFTR modulation currently in clinical trials with an ultimate view to provide modulation therapy to the majority of CF genotypes in the future.

Longitudinal changes in lung function following initiation of lumacaftor/ivacaftor combination

BACKGROUND

The combination of lumacaftor and ivacaftor (LUM/IVA) is a recently approved CFTR modulator treatment for homozygous F508del CF patients. Our study aimed at evaluating the change in the rate of lung function decline after one-year treatment with LUM/IVA.

METHODS

The study evaluated patients homozygous for F508del, 12 to 23 years old. All had been treated for one year with LUM/IVA. The collected data included the percent predicted values of FEV1 (ppFEV1) and FVC (ppFVC), and the FEV1/FVC ratio (FEV1/FVC), that corresponded to 12, 24, and 36 months prior to, and 12 months after the initiation of LUM/IVA; also, the 3 highest values of the ppFEV1 (and the corresponding ppFVC, and FEV1/FVC) for the periods 0-12 months, 12-24 months, and 24-36 months prior to as well as the 12-month period after the initiation of LUM/IVA. The baseline lung function was estimated before the commencement of the drug. Data were analyzed longitudinally with generalized estimating equations models and continuous linear splines. A single knot was used that corresponded to the time point of LUM/IVA initiation.

RESULTS

Fifty-two patients were analyzed. The multivariate longitudinal analysis of spirometric indices with linear splines demonstrated a significant change in the slopes of ppFEV1 and ppFVC decline, reflecting a significant improvement after the initiation of LUM/IVA treatment.

CONCLUSIONS

In this real-world study, lung function improved over a relatively short time period of only one year, after the commencement of LUM/IVA.

Prevention of drug-related complications in cystic fibrosis

PURPOSE OF REVIEW

Due to continuous development of new drugs and better treatment strategies, survival of patients with cystic fibrosis has changed dramatically. Recently, targeted therapy of cystic fibrosis transmembrane conductance regulator (CFTR) modulators have become available. Despite these promising developments, treatment of this complex multiorgan disease constitutes a high and variable amount of other drugs. Complications of pharmacotherapeutic treatment are, therefore, expected to become more prevalent. This gives cause to review drug-related side effects in this new era in cystic fibrosis treatment.

RECENT FINDINGS

We will discuss cystic fibrosis-related pharmacotherapies with a focus on indication of treatment, side effects and their complications, drug--drug interactions, and options to monitor and prevent drug-induced toxicity. Many recent publications about pharmacotherapy in cystic fibrosis, focus on antifungal therapy and CFTR modulators. We will give an overview of the most important studies.

SUMMARY

With increased life expectancy which is, in part, because of better treatment options, the burden of pharmacotherapy in cystic fibrosis patients will increase. This has a high impact on quality of life as pharmacotherapy is time consuming and may cause side effects. Therefore, it is very important to be aware of possible pharmacotherapy-related side effects and their complications, drug--drug interactions, and options to monitor and prevent drug-induced toxicity.

Thickness of the airway surface liquid layer in the lung is affected in cystic fibrosis by compromised synergistic regulation of the ENaC ion channel

The lung epithelium is lined with a layer of airway surface liquid (ASL) that is crucial for healthy lung function. ASL thickness is controlled by two ion channels: epithelium sodium channel (ENaC) and cystic fibrosis (CF) transmembrane conductance regulator (CFTR). Here, we present a minimal mathematical model of ENaC, CFTR and ASL regulation that sheds light on the control of ENaC by the short palate lung and nasal epithelial clone 1 (SPLUNC1) protein and by phosphatidylinositol 4,5-biphosphate (PI(4,5)P₂). The model, despite its simplicity, yields a good fit to experimental observations and is an effective tool for exploring the interplay between ENaC, CFTR and ASL. Steady-state data and dynamic information constrain the model's parameters without ambiguities. Testing the hypothesis that PI(4,5)P₂ protects ENaC from ubiquitination suggests that this protection does not improve the model results and that the control of the ENaC opening probability by PI(4,5)P₂ is sufficient to explain all available data. The model analysis further demonstrates that ASL at the steady state is sensitive to small changes in PI(4,5)P₂ abundance, particularly in CF conditions, which suggests that manipulation of phosphoinositide metabolism may promote therapeutic benefits for CF patients.