Re-imagining cystic fibrosis care: next generation thinking

Advanced pulmonary drug delivery formulations for the treatment of cystic fibrosis

Cystic fibrosis (CF), a fatal genetic condition, causes thick, sticky mucus. It also causes pancreatic dysfunction, bacterial infection, and increased salt loss. Currently available treatments can improve the patient's quality of life. Drug delivery aided by nanotechnology has been explored to alter the pharmacokinetics and toxicity of drugs. In this short review, we aim to summarize various conventional formulations and highlight advanced formulations delivered via the pulmonary route for the treatment of CF. There is considerable interest in advanced drug delivery formulations addressing the various challenges posed by CF. Despite their potential to be translated for clinical use, we anticipate that a significant amount of effort may still be required for translation to the clinic.

Ocular development after highly effective modulator treatment early in life

Highly effective cystic fibrosis (CF) transmembrane conductance regulator (CFTR) modulator therapies (HEMT), including elexacaftor-tezacaftor-ivacaftor, correct the underlying molecular defect causing CF. HEMT decreases general symptom burden by improving clinical metrics and quality of life for most people with CF (PwCF) with eligible CFTR variants. This has resulted in more pregnancies in women living with CF. All HEMT are known to be able pass through the placenta and into breast milk in mothers who continue on this therapy while pregnant and breast feeding. Toxicity studies of HEMT in young rats demonstrated infant cataracts, and case reports have reported the presence of congenital cataracts in early life exposure to HEMT. This article reviews the evidence for how HEMT influences the dynamic and interdependent processes of healthy and abnormal lens development in the context of HEMT exposure during pregnancy and breastfeeding, and raises questions that remain unanswered.

Real-life impact of highly effective CFTR modulator therapy in children with cystic fibrosis

Introduction: Recently, cystic fibrosis transmembrane regulator modulator therapy with elexacaftor/tezacaftor/ivacaftor has become available for children with cystic fibrosis (CF) carrying at least one F508del mutation. Objective: To assess the intermediate term effects of elexacaftor/tezacaftor/ivacaftor in children with cystic fibrosis in a real-world setting. Methods: We performed a retrospective analysis of records of children with cystic fibrosis, who started elexacaftor/tezacaftor/ivacaftor between 8/2020 and 10/2022. Pulmonary function tests, nutritional status, sweat chloride and laboratory data were assessed before, 3 and 6 months after the start of elexacaftor/tezacaftor/ivacaftor respectively. Results: Elexacaftor/tezacaftor/ivacaftor was started in 22 children 6-11 years and in 24 children 12-17 years. Twenty-seven (59%) patients were homozygous for F508del (F/F) and 23 (50%) patients were transitioned from ivacaftor/lumacaftor (IVA/LUM) or tezacaftor/ivacaftor (TEZ/IVA) to elexacaftor/tezacaftor/ivacaftor. Overall, mean sweat chloride concentration decreased by 59.3 mmol/L (95% confidence interval: -65.0 to -53.7 mmol/L, p < 0.0001) under elexacaftor/tezacaftor/ivacaftor. Sweat chloride concentration also decreased significantly after transition from IVA/LUM or TEZ/IVA to elexacaftor/tezacaftor/ivacaftor (-47.8 mmol/l; 95% confidence interval: -57.6 to -37.8 mmol/l, n = 14, p < 0.0001). Sweat chloride reduction was more marked in children with the F/F than in those with the F/MF genotype (69.4 vs 45.9 mmol/L, p < 0.0001). At 3 months follow-up, body-mass-index-z-score increased by 0.31 (95% CI, 0.2-0.42, p < 0.0001) with no further increase at 6 months. BMI-for-age-z-score was more markedly improved in the older group. Overall pulmonary function (percent predicted FEV₁) at 3 months follow-up increased by 11.4% (95% CI: 8.0-14.9, p < 0.0001) with no further significant change after 6 months. No significant differences were noted between the age groups. Children with the F/MF genotype had a greater benefit regarding nutritional status and pulmonary function tests than those with the F/F genotype. Adverse events led to elexacaftor/tezacaftor/ivacaftor dose reduction in three cases and a temporary interruption of therapy in four cases. Conclusion: In a real-world setting, elexacaftor/tezacaftor/ivacaftor therapy had beneficial clinical effects and a good safety profile in eligible children with cystic fibrosis comparable to previously published data from controlled clinical trials. The positive impact on pulmonary function tests and nutritional status seen after 3 months of elexacaftor/tezacaftor/ivacaftor therapy was sustained at 6 months follow-up.

In Utero Mapping and Development Role of CFTR in Lung and Gastrointestinal Tract of Cystic Fibrosis Patients

In cystic fibrosis (CF) the ability of the CF transmembrane conductance regulator (CFTR) protein to mediate chloride and water transport is disrupted. While much progress has been made in CF research leading to effective treatments to improve CFTR function, including small molecule modulators, patients present with varying disease manifestations and responses to therapy. For many CF-affected organs, disease onset is known to occur during in utero development before treatments can be administered and progresses over time leading to irreversible damage to these organs. Thus, the role of functional CFTR protein, in particular, during early development needs to be further elucidated. Studies have detected CFTR proteins at very early gestational stages and revealed temporally and spatially variable CFTR expression patterns in fetuses, suggesting a potential role of CFTR in fetal development. However, the actual mechanisms of how defective CFTR in CF results in fetal morphogenetic abnormalities are yet to be established. This review aims to summarize fetal CFTR expression patterns specifically in the lung, pancreas, and gastrointestinal tract (GIT), as compared to adult patterns. Case studies of structural abnormalities in CF fetuses and newborns and the role of CFTR in fetal development will also be discussed.

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.

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.

Cystic fibrosis year in review 2020: Section 2 pulmonary disease, infections, and inflammation

The outlook for those with cystic fibrosis (CF) has never been brighter with ever increasing life expectancy and the approval of the highly effective CFTR modulators, such as elexacaftor/tezacaftor/ivacaftor. With that being said, the progressive pulmonary decline and importance of lung health, infection, and inflammation in CF remains. This review is the second part in a three-part CF Year in Review 2020. Part one focused on the literature related to CFTR modulators while part three will feature the multisystem effects related to CF. This review focuses on articles from Pediatric Pulmonology, including articles from other journals that are of particular interest to clinicians. Herein, we highlight studies published during 2020 related to CF pulmonary disease, infection, treatment, and diagnostics.

DNA variant classification-reconsidering "allele rarity" and "phenotype" criteria in ACMG/AMP guidelines

Recent guidance suggested modified DNA variant pathogenicity assignments based on genome-wide allele rarity. Different a priori probabilities of pathogenicity operate where patients already have clinical diagnoses, and are found to have a very rare variant in a gene known to cause their disease, compared to predictive testing of a clinically unaffected individual. We tested new recommendations from the ClinGen Sequence Variant Interpretation Working Group for ClinVar-listed, loss-of-function variants meeting the very strong evidence of pathogenicity criterion [PVS1] in genes for 3 specific diseases where causal gene identification can modify clinical care of an individual- Von Willebrand disease, cystic fibrosis and hereditary haemorrhagic telangiectasia. Across these diseases, current rules leave 20/1,278 (1.6%) of loss-of-function variants as variants of uncertain significance (VUS that may not be reported to clinicians), and 207/1,278 (17.2%) as likely pathogenic. Applying the new ClinGen rule enabling PVS1 and the allele rarity criterion PM2 to delineate likely pathogenicity still left 8/1,278 (0.9%) as VUS (reflecting non-PVS1 calls by the submitters), and the majority of null alleles meeting PVS1 as merely likely pathogenic. We favour an approach whereby, for PVS1 variants in patients who personally meet the phenotypic PP4 criterion for a disease where casual variants are commonly family-specific, that PM2 is upgraded to permit a pathogenic call. Of 1,278 ClinVar-listed frameshift, nonsense and canonical splice site variants that met PVS1 in the 3 conditions, 16.0% (204/1,278) would be newly designated as pathogenic, avoiding misinterpretation outside of clinical genetics communities. We suggest further discussion around variant assessment across different clinical applications, potentially guided by PP4 alerts to distinguish personal versus family phenotypic history.

Anti-Inflammatory Influences of Cystic Fibrosis Transmembrane Conductance Regulator Drugs on Lung Inflammation in Cystic Fibrosis

Cystic fibrosis (CF) is caused by a defect in the cystic fibrosis transmembrane conductance regulator protein (CFTR) which instigates a myriad of respiratory complications including increased vulnerability to lung infections and lung inflammation. The extensive influx of pro-inflammatory cells and production of mediators into the CF lung leading to lung tissue damage and increased susceptibility to microbial infections, creates a highly inflammatory environment. The CF inflammation is particularly driven by neutrophil infiltration, through the IL-23/17 pathway, and function, through NE, NETosis, and NLRP3-inflammasome formation. Better understanding of these pathways may uncover untapped therapeutic targets, potentially reducing disease burden experienced by CF patients. This review outlines the dysregulated lung inflammatory response in CF, explores the current understanding of CFTR modulators on lung inflammation, and provides context for their potential use as therapeutics for CF. Finally, we discuss the determinants that need to be taken into consideration to understand the exaggerated inflammatory response in the CF lung.

Resolution-Based Therapies: The Potential of Lipoxins to Treat Human Diseases

Inflammation is an a physiological response instead an essential response of the organism to injury and its adequate resolution is essential to restore homeostasis. However, defective resolution can be the precursor of severe forms of chronic inflammation and fibrosis. Nowadays, it is known that an excessive inflammatory response underlies the most prevalent human pathologies worldwide. Therefore, great biomedical research efforts have been driven toward discovering new strategies to promote the resolution of inflammation with fewer side-effects and more specificity than the available anti-inflammatory treatments. In this line, the use of endogenous specialized pro-resolving mediators (SPMs) has gained a prominent interest. Among the different SPMs described, lipoxins stand out as one of the most studied and their deficiency has been widely associated with a wide range of pathologies. In this review, we examined the current knowledge on the therapeutic potential of lipoxins to treat diseases characterized by a severe inflammatory background affecting main physiological systems, paying special attention to the signaling pathways involved. Altogether, we provide an updated overview of the evidence suggesting that increasing endogenously generated lipoxins may emerge as a new therapeutic approach to prevent and treat many of the most prevalent diseases underpinned by an increased inflammatory response.