Considerations for the Conduct of Clinical Trials with Antiinflammatory Agents in Cystic Fibrosis. A Cystic Fibrosis Foundation Workshop Report

Preclinical murine models for the testing of antimicrobials against Mycobacterium abscessus pulmonary infections: Current practices and recommendations

Mycobacterium abscessus, a rapidly growing nontuberculous mycobacterium, is increasingly recognized as an important pathogen of the human lung, disproportionally affecting people with cystic fibrosis (CF) and other susceptible individuals with non-CF bronchiectasis and compromised immune functions. M. abscessus infections are extremely difficult to treat due to intrinsic resistance to many antibiotics, including most anti-tuberculous drugs. Current standard-of-care chemotherapy is long, includes multiple oral and parenteral repurposed drugs, and is associated with significant toxicity. The development of more effective oral antibiotics to treat M. abscessus infections has thus emerged as a high priority. While murine models have proven instrumental in predicting the efficacy of therapeutic treatments for M. tuberculosis infections, the preclinical evaluation of drugs against M. abscessus infections has proven more challenging due to the difficulty of establishing a progressive, sustained, pulmonary infection with this pathogen in mice. To address this issue, a series of three workshops were hosted in 2023 by the Cystic Fibrosis Foundation (CFF) and the National Institute of Allergy and Infectious Diseases (NIAID) to review the current murine models of M. abscessus infections, discuss current challenges and identify priorities toward establishing validated and globally harmonized preclinical models. This paper summarizes the key points from these workshops. The hope is that the recommendations that emerged from this exercise will facilitate the implementation of informative murine models of therapeutic efficacy testing across laboratories, improve reproducibility from lab-to-lab and accelerate preclinical-to-clinical translation.

Human Mesenchymal Stem Cell (hMSC) Donor Potency Selection for the "First in Cystic Fibrosis" Phase I Clinical Trial (CEASE-CF)

Human Mesenchymal Stem Cell (hMSC) immunotherapy has been shown to provide both anti-inflammatory and anti-microbial effectiveness in a variety of diseases. The clinical potency of hMSCs is based upon an initial direct hMSC effect on the pro-inflammatory and anti-microbial pathophysiology as well as sustained potency through orchestrating the host immunity to optimize the resolution of infection and tissue damage. Cystic fibrosis (CF) patients suffer from a lung disease characterized by excessive inflammation and chronic infection as well as a variety of other systemic anomalies associated with the consequences of abnormal cystic fibrosis transmembrane conductance regulator (CFTR) function. The application of hMSC immunotherapy to the CF clinical armamentarium is important even in the era of modulators when patients with an established disease still need anti-inflammatory and anti-microbial therapies. Additionally, people with CF mutations not addressed by current modulator resources need anti-inflammation and anti-infection management. Furthermore, hMSCs possess dynamic therapeutic properties, but the potency of their products is highly variable with respect to their anti-inflammatory and anti-microbial effects. Due to the variability of hMSC products, we utilized standardized in vitro and in vivo models to select hMSC donor preparations with the greatest potential for clinical efficacy. The models that were used recapitulate many of the pathophysiologic outcomes associated with CF. We applied this strategy in pursuit of identifying the optimal donor to utilize for the "First in CF" Phase I clinical trial of hMSCs as an immunotherapy and anti-microbial therapy for people with cystic fibrosis. The hMSCs screened in this study demonstrated significant diversity in antimicrobial and anti-inflammatory function using models which mimic some aspects of CF infection and inflammation. However, the variability in activity between in vitro potency and in vivo effectiveness continues to be refined. Future studies require and in-depth pursuit of hMSC molecular signatures that ultimately predict the capacity of hMSCs to function in the clinical setting.

α-Tocopherol Pharmacokinetics in Adults with Cystic Fibrosis: Benefits of Supplemental Vitamin C Administration

BACKGROUND

Numerous abnormalities in cystic fibrosis (CF) could influence tocopherol absorption, transportation, storage, metabolism and excretion. We hypothesized that the oxidative distress due to inflammation in CF increases vitamin E utilization, which could be positively influenced by supplemental vitamin C administration.

METHODS

Immediately before and after receiving vitamin C (500 mg) twice daily for 3.5 weeks, adult CF patients (n = 6) with moderately advanced respiratory tract (RT) disease consumed a standardized breakfast with 30% fat and a capsule containing 50 mg each hexadeuterium (d₆)-α- and dideuterium (d₂)-γ-tocopheryl acetates. Blood samples were taken frequently up to 72 h; plasma tocopherol pharmacokinetics were determined. During both trials, d₆-α- and d₂-γ-tocopherols were similarly absorbed and reached similar maximal plasma concentrations ~18-20 h. As predicted, during vitamin C supplementation, the rates of plasma d₆-α-tocopherol decline were significantly slower.

CONCLUSIONS

The vitamin C-induced decrease in the plasma disappearance rate of α-tocopherol suggests that vitamin C recycled α-tocopherol, thereby augmenting its concentrations. We conclude that some attention should be paid to plasma ascorbic acid concentrations in CF patients, particularly to those individuals with more advanced RT inflammatory disease and including those with severe exacerbations.

Recruitment of monocytes primed to express heme oxygenase-1 ameliorates pathological lung inflammation in cystic fibrosis

Overwhelming neutrophilic inflammation is a leading cause of lung damage in many pulmonary diseases, including cystic fibrosis (CF). The heme oxygenase-1 (HO-1)/carbon monoxide (CO) pathway mediates the resolution of inflammation and is defective in CF-affected macrophages (MΦs). Here, we provide evidence that systemic administration of PP-007, a CO releasing/O₂ transfer agent, induces the expression of HO-1 in a myeloid differentiation factor 88 (MyD88) and phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)-dependent manner. It also rescues the reduced HO-1 levels in CF-affected cells induced in response to lipopolysaccharides (LPS) or Pseudomonas aeruginosa (PA). Treatment of CF and muco-obstructive lung disease mouse models with a single clinically relevant dose of PP-007 leads to effective resolution of lung neutrophilia and to decreased levels of proinflammatory cytokines in response to LPS. Using HO-1 conditional knockout mice, we show that the beneficial effect of PP-007 is due to the priming of circulating monocytes trafficking to the lungs in response to infection to express high levels of HO-1. Finally, we show that PP-007 does not compromise the clearance of PA in the setting of chronic airway infection. Overall, we reveal the mechanism of action of PP-007 responsible for the immunomodulatory function observed in clinical trials for a wide range of diseases and demonstrate the potential use of PP-007 in controlling neutrophilic pulmonary inflammation by promoting the expression of HO-1 in monocytes/macrophages.

The activity of an enzyme that is significantly reduced in cystic fibrosis (CF) could be boosted by an existing drug, reducing lung inflammation and associated tissue damage. Chronic inflammation in CF is currently treated using long-term corticosteroids which may leave patients immuno-suppressed, or high-dose ibuprofen, which is not well tolerated. Scientists hope to find alternative therapies targeting chronic inflammation. Emanuela Bruscia, Caterina Di Pietro (Yale University, New Haven, USA) and co-workers examined the mechanisms of action of the first-in-class drug PP-007 (Prolong Pharmaceuticals®) and assessed its potential for controlling inflammation in CF. Patients with CF have reduced expression of the heme oxygenase-1 enzyme in immune cells called monocytes. In CF mouse models, treatment with PP-007 boosted the expression of this enzyme in circulating monocytes. The treatment reduced levels of proinflammatory proteins and associated lung damage.

Changes in airway inflammation with pseudomonas eradication in early cystic fibrosis

BACKGROUND

Neutrophil elastase is a significant risk factor for structural lung disease in cystic fibrosis, and Pseudomonas aeruginosa airway infection is linked with neutrophilic inflammation and substantial respiratory morbidity. We aimed to evaluate how neutrophil elastase (NE) activity changes after P. aeruginosa eradication and influences early disease outcomes.

METHODS

We assessed participants in the AREST CF cohort between 2000 and 2018 who had P. aeruginosa cultured from their routine annual bronchoalveolar lavage (BAL) fluid and who underwent eradication treatment and a post eradication BAL. Factors associated with persistent P. aeruginosa infection, persistent neutrophilic inflammation following eradication and worse structural lung disease one year post-eradication were evaluated.

RESULTS

Eighty-eight episodes (3 months to 6 years old) of P. aeruginosa infection were studied. Eradication was successful in 84.1% of episodes. Median activity of NE was significantly reduced post-eradication from 9.15 to 3.4 nM (p = 0.008) but persisted in 33 subjects. High post-eradication NE levels were associated with an increased risk for P. aeruginosa infection in the next annual visit (odds ratio=1.7, 95% confidence interval 1.1-2.7, p = 0.014). Post-eradication NE levels (difference, 0.8; 95% confidence interval, 0.1-1.5) and baseline bronchiectasis computed tomography (CT) score (difference, 0.4; 95% confidence interval, 0.1-0.8) were the best predictors of bronchiectasis progression within 1 year (backward stepwise linear regression model, R²= 0.608, P<0.001), independent of eradication.

CONCLUSION

In children with CF, NE activity may persist following successful P. aeruginosa eradication and is significantly associated with bronchiectasis progression. Evaluating strategies to diminish neutrophilic inflammation is essential for improving long-term outcomes.

Designing Clinical Trials for Anti-Inflammatory Therapies in Cystic Fibrosis

The inflammatory response in the CF airway begins early in the disease process and becomes persistent through life in most patients. Inflammation, which is predominantly neutrophilic, worsens airway obstruction and plays a critical role in the development of structural lung damage. While cystic fibrosis transmembrane regulator modulators will likely have a dramatic impact on the trajectory of CF lung disease over the coming years, addressing other important aspects of lung disease such as inflammation will nevertheless remain a priority. Considering the central role of neutrophils and their products in the inflammatory response, potential therapies should ultimately affect neutrophils and their products. The ideal anti-inflammatory therapy would exert a dual effect on the pro-inflammatory and pro-resolution arms of the inflammatory cascade, both of which contribute to dysregulated inflammation in CF. This review outlines the key factors to be considered in the design of clinical trials evaluating anti-inflammatory therapies in CF. Important lessons have been learned from previous clinical trials in this area and choosing the right efficacy endpoints is key to the success of any anti-inflammatory drug development program. Identifying and validating non-invasive biomarkers, novel imaging techniques and sensitive lung function tests capable of monitoring disease activity and therapeutic response are important areas of research and will be useful for the design of future anti-inflammatory drug trials.

Accelerated Approval or Risk Reduction? How Response Biomarkers Advance Therapeutics through Clinical Trials in Cystic Fibrosis

Progress in the development of new therapies for cystic fibrosis (CF) has benefited from therapeutically responsive biomarkers to streamline drug development. Paradoxically, these response biomarkers have been proven to be essential even in the presence of data demonstrating a lack of correlation with clinical outcomes across individuals with CF. This finding is unsurprising, particularly in the setting of a rare disease given complex disease processes and an often-limited pool of clinically effective therapies by which to link biomarkers and clinical responsiveness. While many response biomarkers will be unable to progress from their status as markers of biological efficacy to either established correlates of clinical efficacy or surrogate endpoints, they remain critical to the overall success of therapeutic development.

Airway Inflammation and Host Responses in the Era of CFTR Modulators

The arrival of cystic fibrosis transmembrane conductance regulator (CFTR) modulators as a new class of treatment for cystic fibrosis (CF) in 2012 represented a pivotal advance in disease management, as these small molecules directly target the upstream underlying protein defect. Further advancements in the development and scope of these genotype-specific therapies have been transformative for an increasing number of people with CF (PWCF). Despite clear improvements in CFTR function and clinical endpoints such as lung function, body mass index (BMI), and frequency of pulmonary exacerbations, current evidence suggests that CFTR modulators do not prevent continued decline in lung function, halt disease progression, or ameliorate pathogenic organisms in those with established lung disease. Furthermore, it remains unknown whether their restorative effects extend to dysfunctional CFTR expressed in phagocytes and other immune cells, which could modulate airway inflammation. In this review, we explore the effects of CFTR modulators on airway inflammation, infection, and their influence on the impaired pulmonary host defences associated with CF lung disease. We also consider the role of inflammation-directed therapies in light of the widespread clinical use of CFTR modulators and identify key areas for future research.

Evaluation of airway and circulating inflammatory biomarkers for cystic fibrosis drug development

INTRODUCTION

Biomarkers of inflammation in blood and sputum can play a critical role in anti-inflammatory drug development in cystic fibrosis (CF). The objectives of this analysis were to examine relationships between airway and systemic measurements of inflammation, associations between inflammatory biomarkers and FEV₁, differences in airway and systemic inflammation by baseline covariates, reproducibility of serum biomarkers, and to assess the effects of freezing and delayed processing on sputum analyte measurements.

METHODS

We analyzed baseline and serial concentrations of inflammatory markers in blood and induced sputum collected from individuals with CF ages 10 years and older who participated in a multicenter clinical trial.

RESULTS

Among circulating biomarkers, serum high sensitivity C-reactive protein (hsCRP) and serum amyloid A (SAA) correlated most strongly with each other (r_s = 0.85). Comparing sputum-based inflammation measurements, sputum neutrophil elastase and myeloperoxidase (MPO) were the most highly correlated (r_s = 0.88). Markers most strongly correlated with ppFEV₁ were serum hsCRP (r_s = -0.55), SAA (r_s =-0.58), and sputum neutrophil elastase (r_s = -0.53). Within-subject standard deviation was consistently lower than between-subject standard deviation for all serum biomarkers. Serum calprotectin and MPO had the highest ratio of between-to-within subject variability. Freezing and delayed sputum processing were not associated with significant differences in measurements of sputum neutrophil elastase, IL-1β, or MPO.

CONCLUSIONS

Among the biomarkers analyzed, serum hsCRP and sputum neutrophil elastase are promising candidates to include in CF anti-inflammatory clinical trials to avoid redundancy, minimize variation, and serve as correlates of lung disease severity and change.

Building global development strategies for cf therapeutics during a transitional cftr modulator era

As CFTR modulator therapy transforms the landscape of cystic fibrosis (CF) care, its lack of uniform access across the globe combined with the shift towards a new standard of care creates unique challenges for the development of future CF therapies. The advancement of a full and promising CF therapeutics pipeline remains a necessary priority to ensure maximal clinical benefits for all people with CF. It is through collaboration across the global CF community that we can optimize the evaluation and approval process of new therapies. To this end, we must identify areas for which harmonization is lacking and for which efficiencies can be gained to promote ethical, feasible, and credible study designs amidst the changing CF care landscape. This article summarizes the counsel from core advisors across multiple international regions and clinical trial networks, developed during a one-day workshop in October 2019. The goal of the workshop was to identify, in consideration of the highly transitional era of CFTR modulator availability, the drug development areas for which global alignment is currently uncertain, and paths forward that will enable advancement of CF therapeutic development.

Mucus accumulation in the lungs precedes structural changes and infection in children with cystic fibrosis

Although destructive airway disease is evident in young children with cystic fibrosis (CF), little is known about the nature of the early CF lung environment triggering the disease. To elucidate early CF pulmonary pathophysiology, we performed mucus, inflammation, metabolomic, and microbiome analyses on bronchoalveolar lavage fluid (BALF) from 46 preschool children with CF enrolled in the Australian Respiratory Early Surveillance Team for Cystic Fibrosis (AREST CF) program and 16 non-CF disease controls. Total airway mucins were elevated in CF compared to non-CF BALF irrespective of infection, and higher densities of mucus flakes containing mucin 5B and mucin 5AC were observed in samples from CF patients. Total mucins and mucus flakes correlated with inflammation, hypoxia, and oxidative stress. Many CF BALFs appeared sterile by culture and molecular analyses, whereas other samples exhibiting bacterial taxa associated with the oral cavity. Children without computed tomography-defined structural lung disease exhibited elevated BALF mucus flakes and neutrophils, but little/no bacterial infection. Although CF mucus flakes appeared "permanent" because they did not dissolve in dilute BALF matrix, they could be solubilized by a previously unidentified reducing agent (P2062), but not N-acetylcysteine or deoxyribonuclease. These findings indicate that early CF lung disease is characterized by an increased mucus burden and inflammatory markers without infection or structural lung disease and suggest that mucolytic and anti-inflammatory agents should be explored as preventive therapy.

Resolvin D1 Reduces Lung Infection and Inflammation Activating Resolution in Cystic Fibrosis

Non-resolving lung inflammation and Pseudomonas aeruginosa infections are the underlying cause of morbidity and mortality in cystic fibrosis (CF). The endogenous lipid mediator resolvin (Rv) D1 is a potent regulator of resolution, and its roles, actions, and therapeutic potential in CF are of interest. Here, we investigated actions and efficacy of RvD1 in preclinical models of cystic fibrosis. Cftr knockout mice with chronic P. aeruginosa lung infection were treated with RvD1 to assess differences in lung bacterial load, inflammation, and tissue damage. Cells from volunteers with CF were treated with RvD1 during ex vivo infection with P. aeruginosa, and effects on phagocytosis and inflammatory signaling were determined. In CF mice, RvD1 reduced bacterial burden, neutrophil infiltration, and histological signs of lung pathology, improving clinical scores of diseases. Mechanistically, RvD1 increased macrophage-mediated bacterial and leukocyte clearance in vivo. The clinical significance of these findings is supported by actions in primary leukocytes and epithelial cells from volunteers with CF where RvD1 enhanced P. aeruginosa phagocytosis and reduced genes and proteins associated to NF-κB activation and leukocyte infiltration. Concentration of RvD1 in sputum from patients with CF was also inversely correlated to those of cytokines and chemokines involved in CF lung pathology. These findings demonstrate efficacy of RvD1 in enhancing resolution of lung inflammation and infections and provide proof of concept for its potential as a prototypic novel pro-resolutive therapeutic approach for CF.

Anti-inflammatories and mucociliary clearance therapies in the age of CFTR modulators

Cystic fibrosis (CF) is a genetic and life-limiting disease caused by mutations in the CF transmembrane conductance regulator (CFTR) gene. This multi-system disease is characterized by progressive lung disease and pancreatic insufficiency amongst other manifestations. CFTR primarily functions as a chloride channel that transports ions across the apical membrane of epithelial cells but has other functions, including bicarbonate secretion and inhibition of sodium transport. Defective CFTR disrupts these functions, causing viscous and dehydrated mucus to accumulate, compromising the airway lumen and contributing to obstructive pulmonary disease. The combination of CFTR dysfunction, mucus obstruction, and infection drive an exaggerated and dysfunctional inflammatory response, which contributes to irreversible airway destruction and fibrosis. CFTR modulators, an exciting new class of drugs, increase the expression and/or function of CFTR variant protein and improve multiple clinical endpoints, such as lung function, pulmonary exacerbation rates, and nutritional status. However, these genotype-specific drugs are not universally available, the clinical response is variable, and lung function still declines over time when bronchiectasis is established. Consequently, even in the age of CFTR modulators, we must target other important aspects of the CF airway disease, such as inflammation and mucociliary clearance. This review highlights the mechanisms of inflammation and mucus accumulation in the CF lung and discusses anti-inflammatory and mucociliary clearance agents that are currently in development focusing on compounds for which clinical trial data have recently become available.

Innovative Therapies for Cystic Fibrosis: The Road from Treatment to Cure

Cystic fibrosis (CF), a life-threatening multiorgan genetic disease, is facing a new era of research and development using innovative gene-directed personalized therapies. The priority organ to cure is the lung, which suffers recurrent and chronic bacterial infection and inflammation since infancy, representing the main cause of morbidity and precocious mortality of these individuals. After the disappointing failure of gene-replacement approaches using gene therapy vectors, no single drug is presently available to repair all the CF gene defects. The impressive number of different CF gene mutations is now tackled with different chemical and biotechnological tools tailored to the specific molecular derangements, thanks to the extensive knowledge acquired over many years on the mechanisms of CF cell and organ pathology. This review provides an overview and recalls both the successes and limitations of the different experimental approaches, such as high-throughput screening on chemical libraries to discover CF gene correctors and potentiators, dual-acting compounds, read-through molecules, splicing defect repairing tools, cystic fibrosis transmembrane conductance regulator (CFTR) "amplifiers," CFTR interactome modulators and the first gene editing attempts.

Airway Mucosal Host Defense Is Key to Genomic Regulation of Cystic Fibrosis Lung Disease Severity

RATIONALE

The severity of cystic fibrosis (CF) lung disease varies widely, even for Phe508del homozygotes. Heritability studies show that more than 50% of the variability reflects non-cystic fibrosis transmembrane conductance regulator (CFTR) genetic variation; however, the full extent of the pertinent genetic variation is not known.

OBJECTIVES

We sought to identify novel CF disease-modifying mechanisms using an integrated approach based on analyzing "in vivo" CF airway epithelial gene expression complemented with genome-wide association study (GWAS) data.

METHODS

Nasal mucosal RNA from 134 patients with CF was used for RNA sequencing. We tested for associations of transcriptomic (gene expression) data with a quantitative phenotype of CF lung disease severity. Pathway analysis of CF GWAS data (n = 5,659 patients) was performed to identify novel pathways and assess the concordance of genomic and transcriptomic data. Association of gene expression with previously identified CF GWAS risk alleles was also tested.

MEASUREMENTS AND MAIN RESULTS

Significant evidence of heritable gene expression was identified. Gene expression pathways relevant to airway mucosal host defense were significantly associated with CF lung disease severity, including viral infection, inflammation/inflammatory signaling, lipid metabolism, apoptosis, ion transport, Phe508del CFTR processing, and innate immune responses, including HLA (human leukocyte antigen) genes. Ion transport and CFTR processing pathways, as well as HLA genes, were identified across differential gene expression and GWAS signals.

CONCLUSIONS

Transcriptomic analyses of CF airway epithelia, coupled to genomic (GWAS) analyses, highlight the role of heritable host defense variation in determining the pathophysiology of CF lung disease. The identification of these pathways provides opportunities to pursue targeted interventions to improve CF lung health.

Inflammation in cystic fibrosis: An update

Inflammation plays a critical role in cystic fibrosis (CF) lung pathology and disease progression making it an active area of research and important therapeutic target. In this review, we explore the most recent research on the major contributors to the exuberant inflammatory response seen in CF as well as potential therapeutics to combat this response. Absence of functional cystic fibrosis transmembrane conductance regulator (CFTR) alters anion transport across CF airway epithelial cells and ultimately results in dehydration of the airway surface liquid. The dehydrated airway surface liquid in combination with abnormal mucin secretion contributes to airway obstruction and subsequent infection that may serve as a trigger point for inflammation. There is also evidence to suggest that airway inflammation may be excessive and sustained relative to the infectious stimuli. Studies have shown dysregulation of both pro-inflammatory mediators such as IL-17 and pro-resolution mediators including metabolites of the eicosanoid pathway. Recently, CFTR potentiators and correctors have garnered much attention in the CF community. Although these modulators address the underlying defect in CF, their impact on downstream consequences such as inflammation are not known. Here, we review pre-clinical and clinical data on the impact of CFTR modulators on inflammation. In addition, we examine other cell types including neutrophils, macrophages, and T-lymphocytes that express CFTR and contribute to the CF inflammatory response. Finally, we address challenges in developing anti-inflammatory therapies and highlight some of the most promising anti-inflammatory drugs under development for CF.

EMPIRE-CF: A phase II randomized placebo-controlled trial of once-daily, oral acebilustat in adult patients with cystic fibrosis - Study design and patient demographics

Inflammation causes irreparable damage in the cystic fibrosis (CF) lung. Despite high standards of care and the advent of new therapies, inflammation continues to cause significant loss of lung function and morbidity. Acebilustat is a once-daily, oral molecule with anti-inflammatory activity through the inhibition of LTA4 hydrolase and modulation of LTB4. It has potential to reduce lung function decline and pulmonary exacerbations in patients with CF and is currently being tested in a Phase II multicenter, randomized, double-blind, placebo-controlled, parallel-group study (EMPIRE-CF). Strict inclusion criteria based on modeling of the Cystic Fibrosis Foundation Patient Registry data were selected to enrich the trial with patients most likely to benefit from chronic anti-inflammatory therapy that reduces lung function decline. 200 patients between 18 and 30 years of age, with an FEV1 percent predicted (pp) ≥50%, and ≥1 exacerbation in the past year have been enrolled. Patients are randomized 1:1:1 to placebo, acebilustat 50 mg or 100 mg for 48 weeks, taken concomitantly with their current standard of care, and stratified based on concomitant CFTR modulator use, baseline FEV1pp (50% to 75% and >75%), and number of exacerbations in the past year (1 or >1). The primary endpoints are absolute change from baseline in FEV1pp and safety outcomes. Secondary endpoints include rate of pulmonary exacerbations and time to first pulmonary exacerbation. Biomarkers of inflammation will also be assessed. EMPIRE-CF is expected to identify the optimal patient population, dose, duration and endpoints for future acebilustat trials, and widen understanding of the drug's efficacy in patients with CF.

Effects of an Antioxidant-enriched Multivitamin in Cystic Fibrosis. A Randomized, Controlled, Multicenter Clinical Trial

RATIONALE

Cystic fibrosis (CF) is characterized by dietary antioxidant deficiencies, which may contribute to an oxidant-antioxidant imbalance and oxidative stress.

OBJECTIVES

Evaluate the effects of an oral antioxidant-enriched multivitamin supplement on antioxidant concentrations, markers of inflammation and oxidative stress, and clinical outcomes.

METHODS

In this investigator-initiated, multicenter, randomized, double-blind, controlled trial, 73 pancreatic-insufficient subjects with CF 10 years of age and older with an FEV1 between 40% and 100% predicted were randomized to 16 weeks of an antioxidant-enriched multivitamin or control multivitamin without antioxidant enrichment. Endpoints included systemic antioxidant concentrations, markers of inflammation and oxidative stress, clinical outcomes (pulmonary exacerbations, anthropometric measures, pulmonary function), safety, and tolerability.

MEASUREMENTS AND MAIN RESULTS

Change in sputum myeloperoxidase concentration over 16 weeks, the primary efficacy endpoint, was not significantly different between the treated and control groups. Systemic antioxidant (β-carotene, coenzyme Q10, γ-tocopherol, and lutein) concentrations significantly increased in the antioxidant-treated group (P < 0.001 for each), whereas circulating calprotectin and myeloperoxidase decreased in the treated group compared with the control group at Week 4. The treated group had a lower risk of first pulmonary exacerbation requiring antibiotics than the control group (adjusted hazard ratio, 0.50; P = 0.04). Lung function and growth endpoints did not differ between groups. Adverse events and tolerability were similar between groups.

CONCLUSIONS

Antioxidant supplementation was safe and well tolerated, resulting in increased systemic antioxidant concentrations and modest reductions in systemic inflammation after 4 weeks. Antioxidant treatment was also associated with a lower risk of first pulmonary exacerbation. Clinical trial registered with www.clinicaltrials.gov (NCT01859390).

Molecular basis of cystic fibrosis: from bench to bedside

Cystic fibrosis (CF), is an autosomal recessive disease affecting different organs. The lung disease, characterized by recurrent and chronic bacterial infection and inflammation since infancy, is the main cause of morbidity and precocious mortality of these individuals. The innovative therapies directed to repair the defective CF gene should account for the presence of more than 200 disease-causing mutations of the CF transmembrane conductance regulator (CFTR) gene. The review will recall the different experimental approaches in discovering CFTR protein targeted molecules, such as the high throughput screening on chemical libraries to discover correctors and potentiators of CFTR protein, dual-acting compounds, read-through molecules, splicing defects repairing tools, CFTR "amplifiers".

Towards Targeting the Aryl Hydrocarbon Receptor in Cystic Fibrosis

Tryptophan (trp) metabolism is an important regulatory component of gut mucosal homeostasis and the microbiome. Metabolic pathways targeting the trp can lead to a myriad of metabolites, of both host and microbial origins, some of which act as endogenous low-affinity ligands for the aryl hydrocarbon receptor (AhR), a cytosolic, ligand-operated transcription factor that is involved in many biological processes, including development, cellular differentiation and proliferation, xenobiotic metabolism, and the immune response. Low-level activation of AhR by endogenous ligands is beneficial in the maintenance of immune health and intestinal homeostasis. We have defined a functional node whereby certain bacteria species contribute to host/microbial symbiosis and mucosal homeostasis. A microbial trp metabolic pathway leading to the production of indole-3-aldehyde (3-IAld) by lactobacilli provided epithelial protection while inducing antifungal resistance via the AhR/IL-22 axis. In this review, we highlight the role of AhR in inflammatory lung diseases and discuss the possible therapeutic use of AhR ligands in cystic fibrosis.

The EGFR-ADAM17 Axis in Chronic Obstructive Pulmonary Disease and Cystic Fibrosis Lung Pathology

Chronic obstructive pulmonary disease (COPD) and cystic fibrosis (CF) share molecular mechanisms that cause the pathological symptoms they have in common. Here, we review evidence suggesting that hyperactivity of the EGFR/ADAM17 axis plays a role in the development of chronic lung disease in both CF and COPD. The ubiquitous transmembrane protease A disintegrin and metalloprotease 17 (ADAM17) forms a functional unit with the EGF receptor (EGFR), in a feedback loop interaction labeled the ADAM17/EGFR axis. In airway epithelial cells, ADAM17 sheds multiple soluble signaling proteins by proteolysis, including EGFR ligands such as amphiregulin (AREG), and proinflammatory mediators such as the interleukin 6 coreceptor (IL-6R). This activity can be enhanced by injury, toxins, and receptor-mediated external triggers. In addition to intracellular kinases, the extracellular glutathione-dependent redox potential controls ADAM17 shedding. Thus, the epithelial ADAM17/EGFR axis serves as a receptor of incoming luminal stress signals, relaying these to neighboring and underlying cells, which plays an important role in the resolution of lung injury and inflammation. We review evidence that congenital CFTR deficiency in CF and reduced CFTR activity in chronic COPD may cause enhanced ADAM17/EGFR signaling through a defect in glutathione secretion. In future studies, these complex interactions and the options for pharmaceutical interventions will be further investigated.

KB001-A, a novel anti-inflammatory, found to be safe and well-tolerated in cystic fibrosis patients infected with Pseudomonas aeruginosa

BACKGROUND

Chronic Pseudomonas aeruginosa (Pa) airways infection, exuberant local inflammation, and progressive lung function loss are hallmarks of cystic fibrosis (CF). KB001-A is an anti-PcrV PEGylated monoclonal antibody fragment to the Type III secretion system of Pa. This 16-week study evaluated KB001-A associated effect on time-to-need for antibiotics for worsening respiratory signs and symptoms, as well as safety, and treatment-associated changes in symptom scores, inflammatory markers, and spirometry.

METHODS

This was a randomized, double-blind, placebo-controlled, repeat-dose study in CF subjects with Pa. Intravenous 10mg/kg KB001-A or placebo infusions were administered at baseline and weeks 2, 4, 8, and 16, with a 4-week follow-up. Sputum inflammatory markers were assessed in a sub-study. Time-to-need for antibiotics was compared between groups by Kaplan Meier analysis and Cox proportional hazards modeling adjusting for randomization strata.

RESULTS

Of 182 subjects, 169 received at least one infusion of KB001-A (n=83) or placebo (n=86). KB001-A was generally safe and well-tolerated as compared to placebo, with no significant emergent adverse effects other than one serious adverse event of elevated hepatic enzymes of unclear etiology. Time to need for antibiotics did not differ between groups (HR: 1.00; 95% CI: 0.69, 1.45, p=0.995). A 3.2 increase in ppFEV₁ from placebo favoring KB001-A was observed at week 16 (95% CI: 1.12, 5.30, p=0.003). Mean changes from baseline in log₁₀ sputum neutrophil elastase (NE) had a non-significant decrease (-0.27, 95% CI: -0.58,0.04, p=0.084) while IL-8 concentrations at week 16 were significantly lower (-0.27, 95% CI: -0.55,0.00, p=0.048) among KB001-A subjects (n=16) relative to placebo (n=13).

CONCLUSIONS

KB001-A was safe and well-tolerated and associated with a modest FEV₁ benefit and reduction in select sputum inflammatory markers (IL-8). KB001-A was not associated with an increased time to need for antibiotics. The lack of efficacy seen with KB001-A may be due, in part, to the low levels of the type III secretion proteins previously reported in sputum of CF patients chronically infected with Pa.

Mapping targetable inflammation and outcomes with cystic fibrosis biomarkers

Cystic fibrosis is characterized by an overly exuberant neutrophilic inflammatory response to pathogens and other stimuli that starts very early in disease. The overwhelming nature of this response is a primary cause of remodeling and destruction of the airways, suggesting that anti-inflammatory therapies could be beneficial in CF. However, finding therapies that can effectively reduce the inflammatory response without compromising host defenses remains elusive. New approaches towards mapping inflammatory targets promise to aid in developing novel therapeutic strategies and improve outcomes in individuals with CF.

Pseudomonas aeruginosa ExoU augments neutrophil transepithelial migration

Excessive neutrophil infiltration of the lungs is a common contributor to immune-related pathology in many pulmonary disease states. In response to pathogenic infection, airway epithelial cells produce hepoxilin A₃ (HXA₃), initiating neutrophil transepithelial migration. Migrated neutrophils amplify this recruitment by producing a secondary gradient of leukotriene B₄ (LTB₄). We sought to determine whether this two-step eicosanoid chemoattractant mechanism could be exploited by the pathogen Pseudomonas aeruginosa. ExoU, a P. aeruginosa cytotoxin, exhibits phospholipase A2 (PLA2) activity in eukaryotic hosts, an enzyme critical for generation of certain eicosanoids. Using in vitro and in vivo models of neutrophil transepithelial migration, we evaluated the impact of ExoU expression on eicosanoid generation and function. We conclude that ExoU, by virtue of its PLA2 activity, augments and compensates for endogenous host neutrophil cPLA2α function, leading to enhanced transepithelial migration. This suggests that ExoU expression in P. aeruginosa can circumvent immune regulation at key signaling checkpoints in the neutrophil, resulting in exacerbated neutrophil recruitment.

Pseudomonas aeruginosa is an opportunistic pathogen that causes acute pneumonia in immune compromised patients, and infects 70–80% of patients suffering from cystic fibrosis. Infections can result in excessive airway inflammation, which lead to immune-mediated lung damage, in particular through the action of recruited white blood cells known as neutrophils. Certain strains of P. aeruginosa produce the exotoxin ExoU, which has been associated with increased virulence. ExoU causes host cell lysis by hydrolyzing host membrane lipids through its phospholipase activity. However, host phospholipases play a key role in immune signaling by mediating the production of lipids known as eicosanoids. We investigated whether separate from its cytolytic activity, ExoU could modulate host immune responses through its phospholipase activity by hijacking eicosanoid production. Using in vitro and in vivo models of neutrophil recruitment, we find that ExoU producing strains of P. aeruginosa elicit higher levels of the eicosanoid chemoattractant leukotriene B4 from migrated neutrophils. This results in increased neutrophil transepithelial migration. This work reveals a new mechanism for how bacterial pathogens alter our immune function, and highlights a new potential therapeutic strategy for moderating Pseudomonas pathogenesis in patients with cystic fibrosis and acute pneumonia.

Vitamin D treatment modulates immune activation in cystic fibrosis

Persistent inflammatory response in cystic fibrosis (CF) airways is believed to play a central role in the progression of lung damage. Anti-inflammatory treatment may slow lung disease progression, but adverse side effects have limited its use. Vitamin D has immunoregulatory properties. We randomized 16 CF patients to receive vitamin D2, vitamin D3 or to serve as controls, and investigated the effect of vitamin D supplementation on soluble immunological parameters, myeloid dendritic cells (mDCs) and T cell activation. Three months of vitamin D treatment were followed by two washout months. Vitamin D status at baseline was correlated negatively with haptoglobin, erythrocyte sedimentation rate and immunoglobulin A concentration. Total vitamin D dose per kg bodyweight correlated with the down-modulation of the co-stimulatory receptor CD86 on mDCs. Vitamin D treatment was associated with reduced CD279 (PD-1) expression on CD4⁺ and CD8⁺ T cells, as well as decreased frequency of CD8⁺ T cells co-expressing the activation markers CD38 and human leucocyte antigen D-related (HLA-DR) in a dose-dependent manner. There was a trend towards decreased mucosal-associated invariant T cells (MAIT) cell frequency in patients receiving vitamin D and free serum 25-hydroxyvitamin D (free-s25OHD) correlated positively with CD38 expression by these cells. At the end of intervention, the change in free-s25OHD was correlated negatively with the change in CD279 (PD-1) expression on MAIT cells. Collectively, these data indicate that vitamin D has robust pleiotropic immunomodulatory effects in CF. Larger studies are needed to explore the immunomodulatory treatment potential of vitamin D in CF in more detail.

Interactions between Neutrophils and Pseudomonas aeruginosa in Cystic Fibrosis

Cystic fibrosis (CF) affects 70,000 patients worldwide. Morbidity and mortality in CF is largely caused by lung complications due to the triad of impaired mucociliary clearance, microbial infections and chronic inflammation. Cystic fibrosis airway inflammation is mediated by robust infiltration of polymorphonuclear neutrophil granulocytes (PMNs, neutrophils). Neutrophils are not capable of clearing lung infections and contribute to tissue damage by releasing their dangerous cargo. Pseudomonas aeruginosa is an opportunistic pathogen causing infections in immunocompromised individuals. P. aeruginosa is a main respiratory pathogen in CF infecting most patients. Although PMNs are key to attack and clear P. aeruginosa in immunocompetent individuals, PMNs fail to do so in CF. Understanding why neutrophils cannot clear P. aeruginosa in CF is essential to design novel therapies. This review provides an overview of the antimicrobial mechanisms by which PMNs attack and eliminate P. aeruginosa. It also summarizes current advances in our understanding of why PMNs are incapable of clearing P. aeruginosa and how this bacterium adapts to and resists PMN-mediated killing in the airways of CF patients chronically infected with P. aeruginosa.

Phase I Studies of Acebilustat: Biomarker Response and Safety in Patients with Cystic Fibrosis

There is a significant unmet need for safe and effective anti‐inflammatory treatment for cystic fibrosis. The aim of this study was to evaluate the safety of acebilustat, a leukotriene A4 hydrolase inhibitor, and its effect on inflammation biomarkers in patients with cystic fibrosis. Seventeen patients with mild to moderate cystic fibrosis were enrolled and randomized into groups receiving placebo or doses of 50 mg or 100 mg acebilustat administered orally, once daily for 15 days. Sputum neutrophil counts were reduced by 65% over baseline values in patients treated with 100 mg acebilustat. A modestly significant 58% reduction vs. placebo in sputum elastase was observed with acebilustat treatment. Favorable trends were observed for reduction of serum C‐reactive protein and sputum neutrophil DNA in acebilustat‐treated patients. No changes in pulmonary function were observed. Acebilustat was safe and well tolerated. The results of this study support further clinical development of acebilustat for treatment of cystic fibrosis.

Phase I Studies of Acebilustat: Pharmacokinetics, Pharmacodynamics, Food Effect, and CYP3A Induction

Acebilustat is a new once-daily oral antiinflammatory drug in development for treatment of cystic fibrosis (CF) and other diseases. It is an inhibitor of leukotriene A4 hydrolase; therefore, production of leukotriene B4 (LTB4) in biological fluids provides a direct measure of the pharmacodynamic (PD) response to acebilustat treatment. Here we compare the pharmacokinetics (PK) and PD between CF patients and healthy volunteers, and investigate the food effect and CYP3A4 induction in healthy volunteers. No significant differences between study populations were observed for peak plasma level (C_max ) or exposure (AUC). In healthy volunteers, a shift in time to C_max (T_max ) was observed after a high-fat meal, but there was no change in AUC. LTB4 production was reduced in the blood of both populations and in sputum from CF patients. Acebilustat did not induce CYP3A4. These results support continued clinical study of once-daily oral acebilustat in CF at doses of 50 and 100 mg.

Correction of lung inflammation in a F508del CFTR murine cystic fibrosis model by the sphingosine-1-phosphate lyase inhibitor LX2931

Progressive lung disease with early onset is the main cause of mortality and morbidity in cystic fibrosis patients. Here we report a reduction of sphingosine-1-phosphate (S1P) in the lung of unchallenged Cftr^tm1EUR F508del CFTR mutant mice. This correlates with enhanced infiltration by inducible nitric oxide synthase (iNOS)-expressing granulocytes, B cells, and T cells. Furthermore, the ratio of macrophage-derived dendritic cells (MoDC) to conventional dendritic cells (cDC) is higher in mutant mouse lung, consistent with unprovoked inflammation. Oral application of a S1P lyase inhibitor (LX2931) increases S1P levels in mutant mouse tissues. This normalizes the lung MoDC/cDC ratio and reduces B and T cell counts. Lung granulocytes are enhanced, but iNOS expression is reduced in this population. Although lung LyC6+ monocytes are enhanced by LX2931, they apparently do not differentiate to MoDC and macrophages. After challenge with bacterial toxins (LPS-fMLP) we observe enhanced levels of proinflammatory cytokines TNF-α, KC, IFNγ, and IL-12 and the inducible mucin MUC5AC in mutant mouse lung, evidence of deficient resolution of inflammation. LX2931 does not prevent transient inflammation or goblet cell hyperplasia after challenge, but it reduces MUC5AC and proinflammatory cytokine levels toward normal values. We conclude that lung pathology in homozygous mice expressing murine F508del CFTR, which represents the most frequent mutation in CF patients, is characterized by abnormal behavior of infiltrating myeloid cells and delayed resolution of induced inflammation. This phenotype can be partially corrected by a S1P lyase inhibitor, providing a rationale for therapeutic targeting of the S1P signaling pathway in CF patients.