Clinical mechanism of the cystic fibrosis transmembrane conductance regulator potentiator ivacaftor in G551D-mediated cystic fibrosis

Multiomic Investigations into Lung Health and Disease

Diseases of the lung account for more than 5 million deaths worldwide and are a healthcare burden. Improving clinical outcomes, including mortality and quality of life, involves a holistic understanding of the disease, which can be provided by the integration of lung multi-omics data. An enhanced understanding of comprehensive multiomic datasets provides opportunities to leverage those datasets to inform the treatment and prevention of lung diseases by classifying severity, prognostication, and discovery of biomarkers. The main objective of this review is to summarize the use of multiomics investigations in lung disease, including multiomics integration and the use of machine learning computational methods. This review also discusses lung disease models, including animal models, organoids, and single-cell lines, to study multiomics in lung health and disease. We provide examples of lung diseases where multi-omics investigations have provided deeper insight into etiopathogenesis and have resulted in improved preventative and therapeutic interventions.

Icenticaftor, a CFTR Potentiator, in COPD: A Multicenter, Parallel-Group, Double-Blind Clinical Trial

Rationale: CFTR (cystic fibrosis transmembrane conductance regulator) dysfunction is associated with mucus accumulation and worsening chronic obstructive pulmonary disease (COPD) symptoms. Objectives: The aim of this phase IIb dose-finding study was to compare a CFTR potentiator, icenticaftor (QBW251), with placebo in patients with COPD and chronic bronchitis. Methods: Patients with COPD on triple therapy for at least three months were randomized to six treatment arms (icenticaftor 450, 300, 150, 75, or 25 mg or placebo twice daily [b.i.d.]) in a 24-week, multicenter, parallel-group, double-blind study. The primary endpoint was change from baseline in trough FEV1 after 12 weeks. Secondary endpoints included change from baseline in trough FEV1 and Evaluating Respiratory Symptoms in COPD (E-RS) total and cough and sputum scores after 24 weeks. Multiple comparison procedure-modeling was conducted to characterize dose-response relationship. Rescue medication use, exacerbations, and change in serum fibrinogen concentration after 24 weeks were assessed in exploratory and post hoc analyses, respectively. Measurements and Main Results: Nine hundred seventy-four patients were randomized. After 12 weeks of icenticaftor treatment, no dose-response relationship for change from baseline in trough FEV1 was observed; however, it was observed for E-RS cough and sputum score. A dose-response relationship was observed after 24 weeks for trough FEV1, E-RS cough and sputum and total scores, rescue medication use, and fibrinogen. A dose of 300 mg b.i.d. was consistently the most effective. Improvements for 300 mg b.i.d. versus placebo were also seen in pairwise comparisons of these endpoints. All treatments were well tolerated. Conclusions: The primary endpoint was negative, as icenticaftor did not improve trough FEV1 over 12 weeks. Although the findings must be interpreted with caution, icenticaftor improved trough FEV1; reduced cough, sputum, and rescue medication use; and lowered fibrinogen concentrations at 24 weeks. Clinical trial registered with www.clinicaltrials.gov (NCT04072887).

Longitudinal effects of elexacaftor/tezacaftor/ivacaftor on sputum viscoelastic properties, airway infection and inflammation in patients with cystic fibrosis

BACKGROUND

Recent studies demonstrated that the triple combination cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapy elexacaftor/tezacaftor/ivacaftor (ETI) improves lung function and reduces pulmonary exacerbations in cystic fibrosis (CF) patients with at least one F508del allele. However, effects of ETI on downstream consequences of CFTR dysfunction, i.e. abnormal viscoelastic properties of airway mucus, chronic airway infection and inflammation have not been studied. The aim of this study was to determine the longitudinal effects of ETI on airway mucus rheology, microbiome and inflammation in CF patients with one or two F508del alleles aged ≥12 years throughout the first 12 months of therapy.

METHODS

In this prospective observational study, we assessed sputum rheology, the microbiome, inflammation markers and proteome before and 1, 3 and 12 months after initiation of ETI.

RESULTS

In total, 79 patients with CF and at least one F508del allele and 10 healthy controls were enrolled in this study. ETI improved the elastic modulus and viscous modulus of CF sputum at 3 and 12 months after initiation (all p<0.01). Furthermore, ETI decreased the relative abundance of Pseudomonas aeruginosa in CF sputum at 3 months and increased the microbiome α-diversity at all time points. In addition, ETI reduced interleukin-8 at 3 months (p<0.05) and free neutrophil elastase activity at all time points (all p<0.001), and shifted the CF sputum proteome towards healthy.

CONCLUSIONS

Our data demonstrate that restoration of CFTR function by ETI improves sputum viscoelastic properties, chronic airway infection and inflammation in CF patients with at least one F508del allele over the first 12 months of therapy; however, levels close to healthy were not reached.

Ivacaftor therapy post myocardial infarction augments systemic inflammation and evokes contrasting effects with respect to tissue inflammation in brain and lung

Acquired cystic fibrosis transmembrane regulator (CFTR) dysfunctions have been associated with several conditions, including myocardial infarction (MI). Here, CFTR is downregulated in brain, heart, and lung tissue and associates with inflammation and degenerative processes. Therapeutically increasing CFTR expression attenuates these effects. Whether potentiating CFTR function yields similar beneficial effects post-MI is unknown. The CFTR potentiator ivacaftor is currently in clinical trials for treatment of acquired CFTR dysfunction associated with chronic obstructive pulmonary disease and chronic bronchitis. Thus, we tested ivacaftor as therapeutic strategy for MI-associated target tissue inflammation that is characterized by CFTR alterations. MI was induced in male C57Bl/6 mice by ligation of the left anterior descending coronary artery. Mice were treated with ivacaftor starting ten weeks post-MI for two consecutive weeks. Systemic ivacaftor treatment ameliorates hippocampal neuron dendritic atrophy and spine loss and attenuates hippocampus-dependent memory deficits occurring post-MI. Similarly, ivacaftor therapy mitigates MI-associated neuroinflammation (i.e., reduces higher proportions of activated microglia). Systemically, ivacaftor leads to higher frequencies of circulating Ly6C⁺ and Ly6C^hi cells compared to vehicle-treated MI mice. Likewise, an ivacaftor-mediated augmentation of MI-associated pro-inflammatory macrophage phenotype characterized by higher CD80-positivity is observed in the MI lung. In vitro, ivacaftor does not alter LPS-induced CD80 and tumor necrosis factor alpha mRNA increases in BV2 microglial cells, while augmenting mRNA levels of these markers in mouse macrophages and differentiated human THP-1-derived macrophages. Our results suggest that ivacaftor promotes contrasting effects depending on target tissue post-MI, which may be largely dependent on its effects on different myeloid cell types.

Cystic Fibrosis-Related Diabetes Workshop: Research Priorities Spanning Disease Pathophysiology, Diagnosis, and Outcomes

Cystic fibrosis (CF) is a recessive disorder arising from mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) protein. CFTR is expressed in numerous tissues, with high expression in the airways, small and large intestine, pancreatic and hepatobiliary ducts, and male reproductive tract. CFTR loss in these tissues disrupts regulation of salt, bicarbonate, and water balance across their epithelia, resulting in a systemic disorder with progressive organ dysfunction and damage. Pancreatic exocrine damage ultimately manifests as pancreatic exocrine insufficiency that begins as early as infancy. Pancreatic remodeling accompanies this early damage, during which abnormal glucose tolerance can be observed in toddlers. With increasing age, however, insulin secretion defects progress such that CF-related diabetes (CFRD) occurs in 20% of teens and up to half of adults with CF. The relevance of CFRD is highlighted by its association with increased morbidity, mortality, and patient burden. While clinical research on CFRD has greatly assisted in the care of individuals with CFRD, key knowledge gaps on CFRD pathogenesis remain. Furthermore, the wide use of CFTR modulators to restore CFTR activity is changing the CFRD clinical landscape and the field's understanding of CFRD pathogenesis. For these reasons, the National Institute of Diabetes and Digestive and Kidney Diseases and the Cystic Fibrosis Foundation sponsored a CFRD Scientific Workshop, 23-25 June 2021, to define knowledge gaps and needed research areas. This article describes the findings from this workshop and plots a path for CFRD research that is needed over the next decade.

Cystic Fibrosis-Related Diabetes Workshop: Research Priorities Spanning Disease Pathophysiology, Diagnosis, and Outcomes

Cystic fibrosis (CF) is a recessive disorder arising from mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) protein. CFTR is expressed in numerous tissues, with high expression in the airways, small and large intestine, pancreatic and hepatobiliary ducts, and male reproductive tract. CFTR loss in these tissues disrupts regulation of salt, bicarbonate, and water balance across their epithelia, resulting in a systemic disorder with progressive organ dysfunction and damage. Pancreatic exocrine damage ultimately manifests as pancreatic exocrine insufficiency that begins as early as infancy. Pancreatic remodeling accompanies this early damage, during which abnormal glucose tolerance can be observed in toddlers. With increasing age, however, insulin secretion defects progress such that CF-related diabetes (CFRD) occurs in 20% of teens and up to half of adults with CF. The relevance of CFRD is highlighted by its association with increased morbidity, mortality, and patient burden. While clinical research on CFRD has greatly assisted in the care of individuals with CFRD, key knowledge gaps on CFRD pathogenesis remain. Furthermore, the wide use of CFTR modulators to restore CFTR activity is changing the CFRD clinical landscape and the field's understanding of CFRD pathogenesis. For these reasons, the National Institute of Diabetes and Digestive and Kidney Diseases and the Cystic Fibrosis Foundation sponsored a CFRD Scientific Workshop, 23-25 June 2021, to define knowledge gaps and needed research areas. This article describes the findings from this workshop and plots a path for CFRD research that is needed over the next decade.

Effects of lumacaftor-ivacaftor therapy on cystic fibrosis transmembrane conductance regulator function in F508del homozygous patients with cystic fibrosis aged 2-11 years

Rationale: Lumacaftor/ivacaftor was approved for the treatment of patients with cystic fibrosis who are homozygous for F508del aged 2 years and older following positive results from phase three trials. However, the improvement in CFTR function associated with lumacaftor/ivacaftor has only been studied in patients over 12 years of age, while the rescue potential in younger children is unknown. Methods: In a prospective study, we aimed to evaluate the effect of lumacaftor/ivacaftor on the CFTR biomarkers sweat chloride concentration and intestinal current measurement as well as clinical outcome parameters in F508del homozygous CF patients 2-11 years before and 8-16 weeks after treatment initiation. Results: A total of 13 children with CF homozygous for F508del aged 2-11 years were enrolled and 12 patients were analyzed. Lumacaftor/ivacaftor treatment reduced sweat chloride concentration by 26.8 mmol/L (p = 0.0006) and showed a mean improvement in CFTR activity, as assessed by intestinal current measurement in the rectal epithelium, of 30.5% compared to normal (p = 0.0015), exceeding previous findings of 17.7% of normal in CF patients homozygous for F508del aged 12 years and older. Conclusion: Lumacaftor/ivacaftor partially restores F508del CFTR function in children with CF who are homozygous for F508del, aged 2-11 years, to a level of CFTR activity seen in patients with CFTR variants with residual function. These results are consistent with the partial short-term improvement in clinical parameters.

Pharmacologic improvement of CFTR function rapidly decreases sputum pathogen density, but lung infections generally persist

BackgroundLung infections are among the most consequential manifestations of cystic fibrosis (CF) and are associated with reduced lung function and shortened survival. Drugs called CF transmembrane conductance regulator (CFTR) modulators improve activity of dysfunctional CFTR channels, which is the physiological defect causing CF. However, it is unclear how improved CFTR activity affects CF lung infections.MethodsWe performed a prospective, multicenter, observational study to measure the effect of the newest and most effective CFTR modulator, elexacaftor/tezacaftor/ivacaftor (ETI), on CF lung infections. We studied sputum from 236 people with CF during their first 6 months of ETI using bacterial cultures, PCR, and sequencing.ResultsMean sputum densities of Staphylococcus aureus, Pseudomonas aeruginosa, Stenotrophomonas maltophilia, Achromobacter spp., and Burkholderia spp. decreased by 2-3 log10 CFU/mL after 1 month of ETI. However, most participants remained culture positive for the pathogens cultured from their sputum before starting ETI. In those becoming culture negative after ETI, the pathogens present before treatment were often still detectable by PCR months after sputum converted to culture negative. Sequence-based analyses confirmed large reductions in CF pathogen genera, but other bacteria detected in sputum were largely unchanged. ETI treatment increased average sputum bacterial diversity and produced consistent shifts in sputum bacterial composition. However, these changes were caused by ETI-mediated decreases in CF pathogen abundance rather than changes in other bacteria.ConclusionsTreatment with the most effective CFTR modulator currently available produced large and rapid reductions in traditional CF pathogens in sputum, but most participants remain infected with the pathogens present before modulator treatment.Trial RegistrationClinicalTrials.gov NCT04038047.FundingThe Cystic Fibrosis Foundation and the NIH.

Dry Powder Inhalation for Lung Delivery in Cystic Fibrosis

Pulmonary drug delivery has long been used for local and systemic administration of different medications used in acute and chronic respiratory diseases. Certain lung diseases, such as cystic fibrosis, rely heavily on chronic treatments, including targeted lung delivery. Pulmonary drug delivery possesses various physiological advantages compared to other delivery methods and is also convenient for the patient to use. However, the formulation of dry powder for pulmonary delivery proves challenging due to aerodynamic restrictions and the lower tolerance of the lung. The aim of this review is to provide an overview of the respiratory tract structure in patients with cystic fibrosis, including during acute and chronic lung infections and exacerbations. Furthermore, this review discusses the advantages of targeted lung delivery, including the physicochemical properties of dry powder and factors affecting clinical efficacy. Current inhalable drug treatments and drugs currently under development will also be discussed.

ROCK STUDY in CF: sustained anti-inflammatory effects of lumacaftor-ivacaftor in sputum and peripheral blood samples of adult patients with cystic fibrosis-an observational study

BACKGROUND

Previous studies showed that the combination of Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) corrector and potentiator, lumacaftor-ivacaftor (LUMA-IVA) provides meaningful clinical benefits in patients with cystic fibrosis who are homozygous for the Phe508del CFTR mutation. However, little is known about the effect of LUMA-IVA on Proinflammatory Cytokines (PICs).

OBJECTIVES

To investigate the impact of LUMA-IVA CFTR modulation on circulatory and airway cytokines before and after 12 months of LUMA-IVA treatment in a real-world setting.

METHODS

We assessed both plasma and sputum PICs, as well as standard clinical outcomes including Forced Expiratory Volume in one second (FEV₁) %predicted, Body Mass Index (BMI), sweat chloride and pulmonary exacerbations at baseline and prospectively for one year post commencement of LUMA-IVA in 44 patients with cystic fibrosis aged 16 years and older homozygous for the Phe508del CFTR mutation.

RESULTS

Significant reduction in plasma cytokines including interleukin (IL)-8 (p<0.05), tumour necrosis factor (TNF)-α (p<0.001), IL-1ß (p<0.001) levels were observed while plasma IL-6 showed no significant change (p=0.599) post-LUMA-IVA therapy. Significant reduction in sputum IL-6 (p<0.05), IL-8 (p<0.01), IL-1ß (p<0.001) and TNF-α (p<0.001) levels were observed after LUMA-IVA therapy. No significant change was noted in anti-inflammatory cytokine IL-10 levels in both plasma and sputum (p=0.305) and (p=0.585) respectively. Clinically significant improvements in FEV₁ %predicted (mean+3.38%, p=0.002), BMI (mean+0.8 kg/m², p<0.001), sweat chloride (mean -19 mmol/L, p<0.001), as well as reduction in intravenous antibiotics usage (mean -0.73, p<0.001) and hospitalisation (mean -0.38, p=0.002) were observed after initiation of LUMA-IVA therapy.

CONCLUSION

This real-world study demonstrates that LUMA-IVA has significant and sustained beneficial effects on both circulatory and airway inflammation. Our findings suggest that LUMA-IVA may improve inflammatory responses, which could potentially contribute to improved standard clinical outcomes.

Elexacaftor - Tezacaftor - Ivacaftor treatment improves systemic infection parameters and Pseudomonas aeruginosa colonization rate in patients with cystic fibrosis a monocentric observational study

Background & aims

The CFTR-modulating therapy Elexaftor - Tezacaftor - Ivacaftor (ETI) has been widely prescribed since its approval in 2020 in the European Union. The aim of this study was to methodically evaluate the effects of an ETI treatment on clinical, biochemical data and Pseudomonas colonization in order to demonstrate its efficacy.

Methods

This prospective monocentric study comprised 69 patients diagnosed with cystic fibrosis aged at least 12 years and treated with ETI between September 2020 and November 2021. Clinical and laboratory data of each patient and study visit were collected before and after 24 weeks of ETI treatment. Follow-up status of Pseudomonas aeruginosa (PsA) colonization was assessed after one year of therapy by regularly determined sputum or throat swab samples.

Results

Marked improvements biochemical markers of systemic inflammation as white blood cell count, levels of immunoglobulins A, G and M and albumin within 24 weeks of therapy were observed. ETI treatment proved to be effective as seen by amelioration of lung function and sweat chloride concentration. Assessment of PsA colonization status revealed a conversion from a positive to negative detection in 36% of the cases after one year of therapy.

Conclusions

ETI treatment effectively improves systemic inflammation parameters and shows promising results in PsA status conversion.

Microbial Epidemiology of the Cystic Fibrosis Airways: Past, Present, and Future

Progressive obstructive lung disease secondary to chronic airway infection, coupled with impaired host immunity, is the leading cause of morbidity and mortality in cystic fibrosis (CF). Classical pathogens found in the airways of persons with CF (pwCF) include Pseudomonas aeruginosa, Staphylococcus aureus, the Burkholderia cepacia complex, Achromobacter species, and Haemophilus influenzae. While traditional respiratory-tract surveillance culturing has focused on this limited range of pathogens, the use of both comprehensive culture and culture-independent molecular approaches have demonstrated complex highly personalized microbial communities. Loss of bacterial community diversity and richness, counteracted with relative increases in dominant taxa by traditional CF pathogens such as Burkholderia or Pseudomonas, have long been considered the hallmark of disease progression. Acquisition of these classic pathogens is viewed as a harbinger of advanced disease and postulated to be driven in part by recurrent and frequent antibiotic exposure driven by frequent acute pulmonary exacerbations. Recently, CF transmembrane conductance regulator (CFTR) modulators, small molecules designed to potentiate or restore diminished protein levels/function, have been successfully developed and have profoundly influenced disease course. Despite the multitude of clinical benefits, structural lung damage and consequent chronic airway infection persist in pwCF. In this article, we review the microbial epidemiology of pwCF, focus on our evolving understanding of these infections in the era of modulators, and identify future challenges in infection surveillance and clinical management.

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.

Impact of elexacaftor-tezacaftor-ivacaftor on bacterial colonization and inflammatory responses in cystic fibrosis

BACKGROUND

Cystic fibrosis (CF) is a multisystem disease with progressive deterioration. Recently, CF transmembrane conductance regulator (CFTR) modulator therapies were introduced that repair underlying protein defects. Objective of this study was to determine the impact of elexacaftor-tezacaftor-ivacaftor (ETI) on clinical parameters and inflammatory responses in people with CF (pwCF).

METHODS

Lung function (FEV1 ), body mass index (BMI) and microbiologic data were collected at initiation and 3-month intervals for 1 year. Blood was analyzed at baseline and 6 months for cytokines and immune cell populations via flow cytometry and compared to non-CF controls.

RESULTS

Sample size was 48 pwCF, 28 (58.3%) males with a mean age of 28.8 ± 10.7 years. Significant increases in %predicted FEV1 and BMI were observed through 6 months of ETI therapy with no change thereafter. Changes in FEV1 and BMI at 3 months were significantly correlated (r = 57.2, p < 0.01). There were significant reductions in Pseudomonas and Staphylococcus positivity (percent of total samples) in pwCF through 12 months of ETI treatment. Healthy controls (n = 20) had significantly lower levels of circulating neutrophils, interleukin (IL)-6, IL-8, and IL-17A and higher levels of IL-13 compared to pwCF at baseline (n = 48). After 6 months of ETI, pwCF had significant decreases in IL-8, IL-6, and IL-17A levels and normalization of peripheral blood immune cell composition.

CONCLUSIONS

In pwCF, ETI significantly improved clinical outcomes, reduced systemic pro-inflammatory cytokines, and restored circulating immune cell composition after 6 months of therapy.

Mucus aberrant properties in CF: Insights from cells and animal models

Cystic fibrosis (CF), an autosomal genetic disorder caused by the dysfunction of the cystic fibrosis transmembrane conductance regulator (CFTR) protein, is characterized by mucus accumulation in the lungs, the intestinal tract, and the pancreatic ducts. Mucins are high-molecular-weight glycoproteins that govern the biochemical and biophysical properties of mucus. In the CF lung, increased mucus viscoelasticity is associated with decreased mucociliary clearance and defects in host defense mechanisms. The link between defective ion channel and abnormal mucus properties has been investigated in studies involving cell and animal models. In this review article, we discuss recent progress toward understanding the different regions and cells that express CFTR in the airways and how mucus is produced and cleared from the lungs. In addition, we reflect on animal models that provided insights into the organization and the role of the mucin network and how mucus and antimicrobial activities act in concert to protect the lungs from invading pathogens.

Lessons from other fields of medicine, Part 2: Cystic fibrosis

Cystic fibrosis (CF), first described in 1938, is a common, life-limiting monogenetic disease. The discovery of the cystic fibrosis transmembrane conductance regulator (CFTR) gene in 1989 was crucial in advancing our understanding of disease pathogenesis and paving the road for treatment aimed at the fundamental molecular defect. With the delineation of over 2000 variations in the CFTR gene, a sound understanding of the individual variations in cell biology, and electrophysiological abnormalities conferred by the most common defects propelled the advent of targeted disease-modifying therapeutics beginning in 2012. Since then, CF care has transformed beyond just symptomatic treatment to include a variety of small-molecule therapies that address the basic electrophysiologic defect and cause profound improvements in physiology, clinical manifestations, and long-term outcomes, designed to differentially address six genetic/molecular subtypes. This chapter illustrates the progress made toward how fundamental science and translational initiatives enabled personalized, mutation specific treatment. We highlight the importance of preclinical assays and mechanistically-driven development strategies that were coupled with sensitive biomarkers and a clinical trial cooperative to provide a platform for successful drug development. This convergence of academic and private partnerships, and formation of multidisciplinary care teams directed by evidence-based initiatives provide a seminal example of addressing the needs of individuals with a rare, but fatal genetic disease.

Impact of elexacaftor/tezacaftor/ivacaftor on bacterial cultures from people with cystic fibrosis

BACKGROUND

Cystic fibrosis transmembrane conductance regulator (CFTR) modulators have shown beneficial effects on both forced expiratory volume in 1 s (FEV₁ ) and frequency of pulmonary exacerbations in people with cystic fibrosis (CF). These positive outcomes may be related to changes in bacterial colonization within the lungs. Elexacaftor/tezacaftor/ivacaftor (ELX/TEZ/IVA) is the first triple therapy CFTR modulator approved for use in people with CF 6 years and older. This study aimed to determine the impact of ELX/TEZ/IVA on the isolation of Pseudomonas aeruginosa (Pa), methicillin-resistant and methicillin-susceptible Staphylococcus aureus (MRSA and MSSA, respectively) in respiratory cultures.

METHODS

A retrospective chart review of the electronic medical record at the University of Iowa was completed for individuals 12 years and older taking ELX/TEZ/IVA for at least 12 months. The primary outcome was determined by assessing bacterial cultures pre- and postinitiation of ELX/TEZ/IVA. Baseline demographic and clinical characteristics were summarized using mean and standard deviation for continuous outcomes and count and percentage for categorical outcomes. Culture positivity for Pa, MSSA, and MRSA was compared among enrolled subjects between pre- and posttriple combination therapy periods using an exact McNemar's test.

RESULTS

One hundred and twenty-four subjects prescribed ELX/TEZ/IVA for at least 12 months met the requirements for inclusion within our analysis. Culture positivity for Pa, MSSA, and MRSA was approximately 54%, 33%, and 31%, respectively, for the pre-ELX/TEZ/IVA period. Prevalence decreased to approximately 30%, 32%, and 24% (-24.2% [p < 0.0001], -0.7% [p = 1.00], and -6.5% [p = 0.0963], respectively) post-ELX/TEZ/IVA. The source of bacterial culture was predominantly sputum (70.2%) in the pre-ELX/TEZ/IVA group, whereas a throat source (66.1%) was more common post-ELX/TEZ/IVA.

CONCLUSIONS

ELX/TEZ/IVA treatment has an appreciable impact on the detection of common bacterial pathogens in CF respiratory cultures. While previous studies have found a similar effect with single and double CFTR modulator therapies, this is the first single-center study to show the impact of triple therapy, ELX/TEZ/IVA, on bacterial isolation from airway secretions.

Respiratory Infection and Inflammation in Cystic Fibrosis: A Dynamic Interplay among the Host, Microbes, and Environment for the Ages

The interplay between airway inflammation and infection is now recognized as a major factor in the pathobiology in cystic fibrosis (CF). A proinflammatory environment is seen throughout the CF airway resulting in classic marked and enduring neutrophilic infiltrations, irreversibly damaging the lung. Although this is seen to occur early, independent of infection, respiratory microbes arising at different timepoints in life and the world environment perpetuate this hyperinflammatory state. Several selective pressures have allowed for the CF gene to persist until today despite an early mortality. Comprehensive care systems, which have been a cornerstone of therapy for the past few decades, are now revolutionized by CF transmembrane conductance regulator (CTFR) modulators. The effects of these small-molecule agents cannot be overstated and can be seen as early as in utero. For an understanding of the future, this review looks into CF studies spanning the historical and present period.

Nutritional Care in Children with Cystic Fibrosis

Patients with cystic fibrosis (CF) are prone to malnutrition and growth failure, mostly due to malabsorption caused by the derangement in the chloride transport across epithelial surfaces. Thus, optimal nutritional care and support should be an integral part of the management of the disease, with the aim of ameliorating clinical outcomes and life expectancy. In this report, we analyzed the nutrition support across the different ages, in patients with CF, with a focus on the relationships with growth, nutritional status, disease outcomes and the use of the CF transmembrane conductance regulator (CFTR) modulators. The nutrition support goal in CF care should begin as early as possible after diagnosis and include the achievement of an optimal nutritional status to support the growth stages and puberty development in children, that will further support the maintenance of an optimal nutritional status in adult life. The cornerstone of nutrition in patients with CF is a high calorie, high-fat diet, in conjunction with a better control of malabsorption due to pancreatic enzyme replacement therapy, and attention to the adequate supplementation of fat-soluble vitamins. When the oral caloric intake is not enough for reaching the anthropometric nutritional goals, supplemental enteral feeding should be initiated to improve growth and the nutritional status. In the last decade, the therapeutic possibilities towards CF have grown in a consistent way. The positive effects of CFTR modulators on nutritional status mainly consist in the improvement in weight gain and BMI, both in children and adults, and in an amelioration in terms of the pulmonary function and reduction of exacerbations. Several challenges need to be overcome with the development of new drugs, to transform CF from a fatal disease to a treatable chronic disease with specialized multidisciplinary care.

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.

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

BACKGROUND

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

METHODS

Eligible participants had been prescribed a modulator for ≥90 days with re-enrollment allowed upon establishment of a new modulator. Pre-modulator SC values were obtained from chart review; post-modulator sweat was collected and analyzed locally. SC changes were descriptively summarized with biologic sex effects adjusted for age, weight, and CFTR genotype. Heterogeneity in ivacaftor SC response was characterized in relation to published CFTR functional responses.

RESULTS

1848 participants provided 2004 SC measurements, 26.2% on ivacaftor, 39.1% on lumacaftor/ivacaftor, and 34.7% on tezacaftor/ivacaftor. Average SC changes for all modulators were consistent with those reported in previous clinical studies, with greater variation in SC response observed among rarer mutations and notable shifts in the proportion with SC <60mmol/L independent of the magnitude of SC change. Ivacaftor induced in vitro CFTR functional change was significantly correlated with ivacaftor-modulated SC response (Pearson correlation= ‒0.52, 95% CI: ‒0.773, ‒0.129). Average SC change from ivacaftor to tezacaftor/ivacaftor was ‒4.9 mmol/L (n=17,95% CI:‒9.3, ‒0.5) and differed from those switching from lumacaftor/ivacaftor (10.0 mmol/L, n=139, 95% CI:7.8,12.3). Sex at birth was not associated with SC response.

CONCLUSIONS

CHEC-SC is the largest study characterizing modulator-induced SC changes across the CF population. There was a strong association between ivacaftor induced in vitro CFTR function and SC response across a genotypically heterogenous cohort. Biological sex was not associated with SC response.

A phase I study assessing the safety and tolerability of allogeneic mesenchymal stem cell infusion in adults with cystic fibrosis

BACKGROUND

Mesenchymal stem cells are of particular interest in cystic fibrosis (CF) as a potential therapeutic. Data from pre-clinical studies suggest that allogeneic bone marrow-derived human mesenchymal stem cells (hMSCs) may provide a new therapeutic treatment for CF lung disease by attenuating pulmonary inflammation while decreasing bacterial growth and enhancing antibiotic efficacy.

METHODS

Fifteen adults with CF were enrolled in a phase 1 dose-escalation trial of a single intravenous infusion of hMSCs derived from bone marrow aspirates obtained from a single pre-clinically validated healthy volunteer donor. The study employed a 3+3 dose escalation design with subjects receiving a single, intravenous dose of either 1×10⁶, 3×10⁶, or 5×10⁶ hMSCs/kg. Subjects were monitored inpatient for 24 hours and by outpatient visits and telephone calls for 12 months after the infusion. Safety and tolerability were evaluated by monitoring symptoms, patient reported outcome questionnaires, adverse events (AEs), physical exam findings, spirometry, and analyses of safety laboratories. Preliminary evidence for potential efficacy using inflammatory markers in the blood and sputum were also evaluated.

RESULTS

No dose-limiting toxicities, deaths or life-threatening adverse events were observed. Most AEs and serious adverse events (SAEs) were consistent with underlying CF. Vital signs, physical exam findings, spirometry and safety laboratory results showed no significant change from baseline. No trends over time were seen in serum or sputum inflammatory markers nor with clinical spirometry.

CONCLUSION

Allogeneic hMSC intravenous infusions were safe and well-tolerated in this phase 1 study and warrant additional clinical testing as a potential therapeutic for CF lung disease.

Recruited monocytes/macrophages drive pulmonary neutrophilic inflammation and irreversible lung tissue remodeling in cystic fibrosis

Persistent neutrophil-dominated lung inflammation contributes to lung damage in cystic fibrosis (CF). However, the mechanisms that drive persistent lung neutrophilia and tissue deterioration in CF are not well characterized. Starting from the observation that, in patients with CF, c-c motif chemokine receptor 2 (CCR2)⁺ monocytes/macrophages are abundant in the lungs, we investigate the interplay between monocytes/macrophages and neutrophils in perpetuating lung tissue damage in CF. Here we show that CCR2⁺ monocytes in murine CF lungs drive pathogenic transforming growth factor β (TGF-β) signaling and sustain a pro-inflammatory environment by facilitating neutrophil recruitment. Targeting CCR2 to lower the numbers of monocytes in CF lungs ameliorates neutrophil inflammation and pathogenic TGF-β signaling and prevents lung tissue damage. This study identifies CCR2⁺ monocytes as a neglected contributor to the pathogenesis of CF lung disease and as a therapeutic target for patients with CF, for whom lung hyperinflammation and tissue damage remain an issue despite recent advances in CF transmembrane conductance regulator (CFTR)-specific therapeutic agents.

Inflammation and Infection in Cystic Fibrosis: Update for the Clinician

Inflammation and infection play an important role in the pathophysiology of cystic fibrosis, and they are significant causes of morbidity and mortality in CF. The presence of thick mucus in the CF airways predisposes to local hypoxia and promotes infection and inflammation. A vicious cycle of airway obstruction, inflammation, and infection is of critical importance for the progression of the disease, and new data elucidate the different factors that influence it. Recent research has been focused on improving infection and inflammation in addition to correcting the basic gene defect. This review aims to summarize important advances in infection and inflammation as well as the effect of new treatments modulating the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) protein. New approaches to target infection and inflammation are being studied, including gallium, nitric oxide, and phage therapy for infection, along with retinoids and neutrophil elastase inhibitors for inflammation.

Emerging Approaches to Monitor and Modify Care in the Era of Cystic Fibrosis Transmembrane Conductance Regulators

As we characterize the clinical benefits of highly effective modulator therapy (HEMT) in the cystic fibrosis (CF) population, our paradigm for treating and monitoring disease continues to evolve. More sensitive approaches are necessary to detect early disease and clinical progression. This article reviews evolving strategies to assess disease control and progression in the HEMT era. This article also explores developments in pulmonary function monitoring, advanced respiratory imaging, tools for the collection of patient-reported outcomes, and their application to profile individual responses, guide therapeutic decisions, and improve the quality of life of people with CF.

Novel Applications of Biomarkers and Personalized Medicine in Cystic Fibrosis

As routine care in cystic fibrosis (CF) becomes increasingly personalized, new opportunities to further focus care on the individual have emerged. These opportunities are increasingly filled through research in tools aiding drug selection, drug monitoring and titration, disease-relevant biomarkers, and evaluation of therapeutic benefits. Herein, we will discuss such research tools presently being translated into the clinic to improve the personalization of care in CF.

Update on Clinical Outcomes of Highly Effective Modulator Therapy

Based on the cystic fibrosis transmembrane conductance regulator (CFTR) genotype, approximately 90% of people with cystic fibrosis (CF) are candidates for highly effective modulator therapy (HEMT). Clinical trials conducted over the last 11 years have shown that these oral therapies substantially restore CFTR function, leading to improvements in lung function, nutritional status, and health-related quality of life. Here, we review safety and efficacy data from phase 3 clinical trials and observational studies which support the use of HEMT in most adults and children with CF. We also discuss opportunities for additional investigation in groups underrepresented or excluded from phase 3 clinical trials, and challenges in the evaluation of the safety and efficacy of HEMT at increasingly earlier stages of CFTR-mediated pathophysiology.

Nontuberculous Mycobacterial Infections in Cystic Fibrosis

Nontuberculous mycobacteria (NTM) are important pathogens, with a longitudinal prevalence of up to 20% within the cystic fibrosis (CF) population. Diagnosis of NTM pulmonary disease in people with CF (pwCF) is challenging, as a majority have NTM infection that is transient or indolent, without evidence of clinical consequence. In addition, the radiographic and clinical manifestations of chronic coinfections with typical CF pathogens can overlap those of NTM, making diagnosis difficult. Comprehensive care of pwCF must be optimized to assess the true clinical impact of NTM and to improve response to treatment. Treatment requires prolonged, multidrug therapy that varies depending on NTM species, resistance pattern, and extent of disease. With a widespread use of highly effective modulator therapy (HEMT), clinical signs and symptoms of NTM disease may be less apparent, and sensitivity of sputum cultures further reduced. The development of a disease-specific approach to the diagnosis and treatment of NTM infection in pwCF is a research priority, as a lifelong strategy is needed for this high-risk population.

The Impact of Highly Effective Modulator Therapy on Cystic Fibrosis Microbiology and Inflammation

Highly effective cystic fibrosis (CF) transmembrane conductance regulator (CFTR) modulator therapy (HEMT) corrects the underlying molecular defect causing CF disease. HEMT decreases symptom burden and improves clinical metrics and quality of life for most people with CF (PwCF) and eligible cftr mutations. Improvements in measures of pulmonary health suggest that restoration of function of defective CFTR anion channels by HEMT not only enhances airway mucociliary clearance, but also reduces chronic pulmonary infection and inflammation. This article reviews the evidence for how HEMT influences the dynamic and interdependent processes of infection and inflammation in the CF airway, and what questions remain unanswered.

Effects of ivacaftor on systemic inflammation and the plasma proteome in people with CF and G551D

BACKGROUND

Ivacaftor is a cystic fibrosis transmembrane conductance regulator (CFTR) potentiator for people with CF and the G551D mutation. We aimed to investigate the biology of CFTR modulation and systemic effects of CFTR restoration by examining changes in circulating measurements of inflammation and growth and novel proteins with ivacaftor treatment.

METHODS

Blood samples from 64 CF subjects with G551D-CFTR were analyzed for inflammatory and growth-related proteins at baseline, 1 and 6 months after ivacaftor initiation. In 30 subjects, plasma was assayed for 1,322 proteins using the SomaScan proteomic platform at baseline and 6 months post-ivacaftor. Correlations with clinical outcomes were assessed.

MEASUREMENTS AND MAIN RESULTS

Significant reductions in high mobility group box-1 protein (HMGB-1), calprotectin, serum amyloid A, and granulocyte colony-stimulating factor (G-CSF), and an increase in insulin-like growth factor (IGF-1) occurred 1 month after ivacaftor. This treatment effect was sustained at 6 months for HMGB-1 and calprotectin. Correcting for multiple comparisons in the proteomic analysis, 9 proteins (albumin, afamin, leptin, trypsin, pancreatic stone protein [PSP], pituitary adenylate cyclase-activating polypeptide-38, repulsive guidance molecule A [RGMA], calreticulin, GTPase KRas) changed significantly with ivacaftor. Proteins changing with treatment are involved in lipid digestion and transport and extracellular matrix organization biological processes. Reductions in calprotectin and G-CSF and increases in calreticulin, and RGMA correlated with improved lung function, while increasing IGF-1, leptin and afamin and decreasing PSP correlated with increased weight.

CONCLUSIONS

Ivacaftor led to changes in inflammatory, lipid digestion, and extracellular matrix proteins, lending insights into the extrapulmonary effects of CFTR modulation.

Preclinical evaluation of the epithelial sodium channel inhibitor AZD5634 and implications on human translation

Airway dehydration causes mucus stasis and bacterial overgrowth in cystic fibrosis (CF), resulting in recurrent respiratory infections and exacerbations. Strategies to rehydrate airway mucus including inhibition of the epithelial sodium channel (ENaC) have the potential to improve mucosal defense by enhancing mucociliary clearance (MCC) and reducing the risk of progressive decline in lung function. In the current work, we evaluated the effects of AZD5634, an ENaC inhibitor that shows extended lung retention and safety profile as compared with previously evaluated candidate drugs, in healthy and CF preclinical model systems. We found that AZD5634 elicited a potent inhibition of amiloride-sensitive current in non-CF airway cells and airway cells derived from F508del-homozygous individuals with CF that effectively increased airway surface liquid volume and improved mucociliary transport (MCT) rate. AZD5634 also demonstrated efficacious inhibition of ENaC in sheep bronchial epithelial cells, translating to dose-dependent improvement of mucus clearance in healthy sheep in vivo. Conversely, nebulization of AZD5634 did not notably improve airway hydration or MCT in CF rats that exhibit an MCC defect, consistent with findings from a first single-dose evaluation of AZD5634 on MCC in people with CF. Overall, these findings suggest that CF animal models demonstrating impaired mucus clearance translatable to the human situation may help to successfully predict and promote the successful translation of ENaC-directed therapies to the clinic.

Physiology and pathophysiology of human airway mucus

The mucus clearance system is the dominant mechanical host defense system of the human lung. Mucus is cleared from the lung by cilia and airflow, including both two-phase gas-liquid pumping and cough-dependent mechanisms, and mucus transport rates are heavily dependent on mucus concentration. Importantly, mucus transport rates are accurately predicted by the gel-on-brush model of the mucociliary apparatus from the relative osmotic moduli of the mucus and periciliary-glycocalyceal (PCL-G) layers. The fluid available to hydrate mucus is generated by transepithelial fluid transport. Feedback interactions between mucus concentrations and cilia beating, via purinergic signaling, coordinate Na+ absorptive vs Cl- secretory rates to maintain mucus hydration in health. In disease, mucus becomes hyperconcentrated (dehydrated). Multiple mechanisms derange the ion transport pathways that normally hydrate mucus in muco-obstructive lung diseases, e.g., cystic fibrosis (CF), chronic obstructive pulmonary disease (COPD), non-CF bronchiectasis (NCFB), and primary ciliary dyskinesia (PCD). A key step in muco-obstructive disease pathogenesis is the osmotic compression of the mucus layer onto the airway surface with the formation of adherent mucus plaques and plugs, particularly in distal airways. Mucus plaques create locally hypoxic conditions and produce airflow obstruction, inflammation, infection, and, ultimately, airway wall damage. Therapies to clear adherent mucus with hydrating and mucolytic agents are rational, and strategies to develop these agents are reviewed.

Elexacaftor-Tezacaftor-Ivacaftor improve Gastro-Oesophageal reflux and Sinonasal symptoms in advanced cystic fibrosis

Upper gastrointestinal and upper airway disease are common in cystic fibrosis (CF) and may contribute to lower airway infection and inflammation. In a longitudinal cohort study of 32 patients (23 men; median age 32.5 years) with advanced CF lung disease (median FEV₁ 24.8% predicted) starting elexacaftor-tezacaftor-ivacaftor, the reflux symptom index score fell from a pre-treatment median (IQR) of 15 (11-23) to 5 (2.8-7.3) (p<0.001), the Hull airway reflux score fell from a median of 26.5 (16.3-39) to 7.5 (4-12) (p<0.001), and the sinonasal outcome score from a median of 36.5 (22-24) to 20 (10-32) (p<0.001) at 6 months on treatment. Mean FEV₁% predicted rose by 9.2 points, the median respiratory domain score of the CF Questionnaire-Revised rose by 27.8 points and mean body mass index rose by 2.6 kg/m². In addition to improving lung function and weight, CFTR modulators improve upper airway and gastro-oesophageal reflux symptoms in advanced CF.

Evaluation of a novel CFTR potentiator in COPD ferrets with acquired CFTR dysfunction

RATIONALE

The majority of chronic obstructive pulmonary disease (COPD) patients have chronic bronchitis, for which specific therapies are unavailable. Acquired cystic fibrosis transmembrane conductance regulator (CFTR) dysfunction is observed in chronic bronchitis, but has not been proven in a controlled animal model with airway disease. Furthermore, the potential of CFTR as a therapeutic target has not been tested in vivo, given limitations to rodent models of COPD. Ferrets exhibit cystic fibrosis-related lung pathology when CFTR is absent and COPD with bronchitis following cigarette smoke exposure.

OBJECTIVES

To evaluate CFTR dysfunction induced by smoking and test its pharmacological reversal by a novel CFTR potentiator, GLPG2196, in a ferret model of COPD with chronic bronchitis.

METHODS

Ferrets were exposed for 6 months to cigarette smoke to induce COPD and chronic bronchitis and then treated with enteral GLPG2196 once daily for 1 month. Electrophysiological measurements of ion transport and CFTR function, assessment of mucociliary function by one-micron optical coherence tomography imaging and particle-tracking microrheology, microcomputed tomography imaging, histopathological analysis and quantification of CFTR protein and mRNA expression were used to evaluate mechanistic and pathophysiological changes.

MEASUREMENTS AND MAIN RESULTS

Following cigarette smoke exposure, ferrets exhibited CFTR dysfunction, increased mucus viscosity, delayed mucociliary clearance, airway wall thickening and airway epithelial hypertrophy. In COPD ferrets, GLPG2196 treatment reversed CFTR dysfunction, increased mucus transport by decreasing mucus viscosity, and reduced bronchial wall thickening and airway epithelial hypertrophy.

CONCLUSIONS

The pharmacologic reversal of acquired CFTR dysfunction is beneficial against pathological features of chronic bronchitis in a COPD ferret model.

An Update on CFTR Modulators as New Therapies for Cystic Fibrosis

Over the past decade there have been significant developments in the field of Cystic Fibrosis Transmembrane Regulator modulator drugs. Following treatment in patients with cystic fibrosis with common gating mutations using the potentiator drug ivacaftor, successive development of corrector drugs used in combination has led to highly effective modulator therapy being available to more than 85% of the cystic fibrosis population over 12 years of age in the form of elexacaftor/tezacaftor/ivacaftor. In this article, we review the evidence from clinical trials and mounting real-world observational and registry data that demonstrates the impact highly effective modulators have on both pulmonary and extra-pulmonary manifestations of cystic fibrosis. As clinical trials progress to younger patient groups, we discuss the challenges to demonstrating drug efficacy in early life, and also consider practicalities of drug development in an ever-shrinking modulator-naïve population. Drug-drug interactions are an important consideration in people with cystic fibrosis, where polypharmacy is commonplace, but also as the modulated population look to remain healthier for longer, we identify trials that aim to address treatment burden too. Inequity of care, through drug cost or ineligibility for modulators by genotype, is widening without apparent strategies to address this; however, we present evidence of hopeful early-stage drug development for non-modulatable genes and summarise the current state of gene-therapy development.

Changes in Glucose Breath Test in Cystic Fibrosis Patients Treated With 1 Month of Lumacaftor/Ivacaftor

BACKGROUND

Alteration of the airway microbiota is a hallmark of cystic fibrosis (CF) pulmonary disease. Dysfunction of cystic fibrosis transmembrane regulator (CFTR) in the intestine also promotes changes in local microbiota such as small intestinal bacterial overgrowth (SIBO), which is common in CF. We evaluated whether therapy with the CFTR modulator combination lumacaftor/ivacaftor (luma/iva) has a beneficial impact on SIBO as measured by breath testing (BT).

METHODS

A multicenter longitudinal study of CFTR-dependent disease profiling (NCT02477319) included a prospective evaluation for SIBO by BT. Tidal breath samples were collected after fasting and 15, 30, 45, 60, 90, and 120 minutes after ingestion of glucose, before and 1 month after subjects initiated luma + iva.

RESULTS

Forty-two subjects enrolled in the sub-study (mean age = 23.3 years; 51% female; 9.5% Latinx); 38 completed a hydrogen BT at both time points, of which 73.7% had a positive BT before luma/iva (baseline) and 65.8% had a positive test after luma/iva ( P = 0.44); shifts from negative to positive were also seen. Use of azithromycin (63.1%) and inhaled antibiotics (60.5%) were not associated with positive BT. Acid-blocking medications were taken by 73% of those with a negative BT at baseline and by 35% with a positive baseline BT ( P = 0.04).

CONCLUSION

We found a high rate of positive hydrogen breath tests in individuals with CF, confirming that SIBO is common. One month of luma/iva did not significantly change the proportion of those with positive breath hydrogen measurements.

Inflammation biomarkers in sputum for clinical trials in cystic fibrosis: current understanding and gaps in knowledge

RATIONALE

Sputum biomarkers hold promise as a direct measure of inflammation within the cystic fibrosis (CF) lung, but variability in study design and sampling methodology have limited their use. A full evaluation of the reliability, validity and clinical relevance of individual biomarkers is required to optimise their use within CF clinical research.

OBJECTIVES

A biomarker Special Interest Working Group was established within the European Cystic Fibrosis Society-Clinical Trials Network Standardisation Committee, to perform a review of the evidence regarding sputum biomarkers in CF.

METHODS

From the 139 included articles, we identified 71 sputum biomarkers to undergo evaluation of their clinimetric properties, responsiveness, discriminant, concurrent and convergent validity.

RESULTS

Current evidence confirms the potential of sputum biomarkers as outcome measures in clinical trials. Inconsistency in responsiveness, concurrent and convergent validity require further research into these markers and processing standardisation before translation into wider use. Of the 71 biomarkers identified, Neutrophil Elastase (NE), IL-8, TNF-α and IL-1β, demonstrated validity and responsiveness to be currently considered for use in clinical trials. Other biomarkers show future promise, including IL-6, calprotectin, HMGB-1 and YKL-40.

CONCLUSION

A concerted international effort across the cystic fibrosis community is needed to promote high quality biomarker trial design, establish large population-based biomarker studies, and work together to create standards for collection, storage and analysis of sputum biomarkers.

Modulation, microbiota and inflammation in the adult CF gut: A prospective study

BACKGROUND

Cystic Fibrosis (CF) has prominent gastrointestinal and pancreatic manifestations. The aim of this study was to determine the effect of Cystic fibrosis transmembrane conductance regulator (CFTR) modulation on, gastrointestinal inflammation, pancreatic function and gut microbiota composition in people with cystic fibrosis (CF) and the G551D-CFTR mutation.

METHODS

Fourteen adult patients with the G551D-CFTR mutation were assessed clinically at baseline and for up to 1 year after treatment with ivacaftor. The change in gut inflammatory markers (calprotectin and lactoferrin), exocrine pancreatic status and gut microbiota composition and structure were assessed in stool samples.

RESULTS

There was no significant change in faecal calprotectin nor lactoferrin in patients with treatment while all patients remained severely pancreatic insufficient. There was no significant change in gut microbiota diversity and richness following treatment.

CONCLUSION

There was no significant change in gut inflammation after partial restoration of CFTR function with ivacaftor, suggesting that excess gut inflammation in CF is multi-factorial in aetiology. In this adult cohort, exocrine pancreatic function was irreversibly lost. Longer term follow-up may reveal more dynamic changes in the gut microbiota and possible restoration of CFTR function.

Ivacaftor Alters Macrophage and Lymphocyte Infiltration in the Lungs Following Lipopolysaccharide Exposure

Background and purpose: Cystic fibrosis (CF) is associated with a myriad of respiratory complications including increased susceptibility to lung infections and inflammation. Progressive inflammatory insults lead to airway damage and remodeling, resulting in compromised lung function. Treatment with ivacaftor significantly improves respiratory function and reduces the incidence of pulmonary exacerbations; however, its effect on lung inflammation is yet to be fully elucidated. Experimental approach: This study investigates the effects of ivacaftor on lung inflammation in a lipopolysaccharide (LPS) exposure mouse model (C57BL/6). All groups received intratracheal (IT) administration of LPS (10 μg). Prophylactic treatment involved intraperitoneal injections of ivacaftor (40 mg/kg) once a day beginning 4 days prior to LPS challenge. The therapeutic group received a single intraperitoneal ivacaftor injection (40 mg/kg) directly after LPS. Mice were culled either 24 or 72 h after LPS challenge, and serum, bronchoalveolar lavage fluid (BALF), and lung tissue samples were collected. The degree of inflammation was assessed through cell infiltration, cytokine expression, and histological analysis. Key results: Ivacaftor did not decrease the total number of immune cells within the BALF; however, prophylactic treatment did significantly reduce macrophage and lymphocyte infiltration. Prophylactic treatment exhibited a significant negative correlation between the immune cell number and ivacaftor concentrations in BALF; however, no significant changes in the cytokine expression or histological parameters were determined. Conclusions and implications: Ivacaftor possesses some inherent immunomodulatory effects within the lungs following LPS inoculation; however, further analysis of larger sample sizes is required to confirm the results.

CFTR modulator therapies - Effect on life expectancy in people with cystic fibrosis

CFTR modulators have dramatically changed the clinical course of CF in those fortunate enough to receive them. Inevitably, randomised controlled trials during the development of these drugs are too short to use mortality as an outcome. Evidence for their effect on life expectancy are best gained from real world registry studies specifically looking at mortality, but these are only available for ivacaftor to date. Therefore, indirect evidence must be obtained by looking at outcomes known to affect mortality and seeing the effect of these drugs on those outcomes.

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.