Inhaled dry powder mannitol in cystic fibrosis: an efficacy and safety study

Improving complex medical care while awaiting next-generation CFTR potentiators and correctors: The current pipeline of therapeutics

While a major target in cystic fibrosis (CF) research in recent years has been the development of corrector and potentiator drugs targeting the cystic fibrosis transmembrane conductance regulator (CFTR) protein, these therapies have not yet proven robust enough to replace or eliminate other therapies that have demonstrated improved health outcomes and quality of life in patients with CF. Further, ivacaftor is only indicated for approximately 5% of the US CF population, although the FDA has recently approved lumacaftor/ivacaftor, a combination therapy intended for those homozygous for Phe508del, which should reach a much larger number of patients. This review appraises therapeutics currently available or being studied while we await the next generation of CFTR potentiators and correctors.

Inhaled therapy in cystic fibrosis: agents, devices and regimens

Key points

Summary

The recognised mainstay daily treatments for cystic fibrosis (CF) focus on inhaled and oral medications, airway clearance and optimised nutrition. This review discusses recent advances in inhaled therapies for the management of CF, including devices such as intelligent nebulisers, drug formulations and supporting evidence for inhaled antibiotics (for the management of chronic Pseudomonas aeruginosa) and muco-active drugs. We include practical advice for clinicians regarding the optimisation of inhalation technique and education. The influence of adherence on the use of inhaled therapies in CF is also reviewed.

Educational aims

Optimising inhaled mannitol for cystic fibrosis in an adult population

Abstract

There has been remarkable progress in the treatment of cystic fibrosis (CF) patients over the past 20 years. However, limitations of standard therapies have highlighted the need for a convenient alternative treatment to effectively target the pathophysiologic basis of CF-related disease by improving mucociliary clearance of airway secretions and consequently improve lung function and reduce respiratory exacerbations. Mannitol is an osmotic agent available as a dry powder, dispensed in a convenient disposable inhaler device for the treatment of adult patients with CF. Inhalation of mannitol as a dry powder is thought to change the viscoelastic properties of airway secretions, increase the hydration of the airway surface liquid and contribute to increased mucociliary and cough clearance of retained secretions. In two large phase 3 studies [1, 2], long-term use of inhaled mannitol resulted in a significant and clinically meaningful improvement in lung function relative to control in adult CF subjects and had an acceptable safety profile. Clinical experience with inhaled mannitol confirms that it is safe and effective. A minority of patients are unable to tolerate the medication. However, through training in proper inhaler technique and setting clear expectations regarding therapeutic effects, both the tolerance and adherence necessary for long term efficacy can be positively influenced.

Educational aims

Key points

Effect of ivacaftor treatment in patients with cystic fibrosis and the G551D-CFTR mutation: patient-reported outcomes in the STRIVE randomized, controlled trial

BACKGROUND

Cystic fibrosis (CF) is an inherited, rare autosomal recessive disease that results in chronically debilitating morbidities and high premature mortality. We evaluated how ivacaftor treatment affected CF symptoms, functioning, and well-being, as measured by the Cystic Fibrosis Questionnaire-Revised (CFQ-R), a widely-used patient-reported outcome (PRO) measure.

METHODS

STRIVE, a double-blind, placebo-controlled randomized trial, evaluated ivacaftor (150 mg) in CF patients aged 12+ with the G551D-CFTR mutation for 48 weeks. Treatment effect analysis used a mixed-effects repeated measures model. Treatment benefit analyses applied the cumulative distribution function and a categorical analysis of change scores ("improvement," "no change," or "decline"). Content-based interpretation examined treatment effect on specific item responses.

RESULTS

Data from 152 patients with a baseline CFQ-R assessment were analyzed. The treatment effect analysis favored treatment with ivacaftor over placebo on the Body Image, Eating, Health Perceptions, Physical Functioning, Respiratory, Social Functioning, Treatment Burden, and Vitality scales. Findings were supported by the analysis of categorical change. On all CFQ-R scales, the percentage of patients who improved was greater for ivacaftor. In the content-based analysis, the treatment benefit was characterized by better scores across a broad range of domains.

CONCLUSIONS

Results illustrate broad benefits of ivacaftor treatment across many domains: respiratory symptoms, physical and social functioning, health perceptions, and vitality, as measured by the CFQ-R. The breadth of improvements reflects the systemic mechanism of action of ivacaftor compared to other therapies. Findings support the patient-reported value of ivacaftor treatment in this patient population.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00909532.

Characterization of a New High-Dose Dry Powder Inhaler (DPI) Based on a Fluidized Bed Design

The objective of this study was to develop a new high-efficiency dry powder inhaler (DPI) that can effectively aerosolize large masses (25-100 mg) of spray dried powder formulations. The DPI was designed to implement a concept similar to a fluidized bed for aerosolization using small mixing balls made of polytetrafluoroethylene along with a larger, hollow dosing sphere filled with the powder. The performance of the fluidized bed DPI was compared, based on emitted dose (ED) and aerosolization efficiency, to other recently developed capsule-based DPIs that were designed to accommodate smaller powder masses (~2-20 mg). The inhalers were tested with spray dried excipient enhanced growth (EEG) formulations that contained an antibiotic (ciprofloxacin) and hygroscopic excipient (mannitol). The new fluidized bed design produced an ED of 71% along with a mass median aerodynamic diameter of 1.53 μm and fine particle fractions <5 and 1 μm of 93 and 36%, respectively, when used to deliver a 100 mg loaded mass of EEG powder with the advantage of not requiring multiple capsules. Surprisingly, performance of the device was further improved by removing the mixing balls from the inhaler and only retaining the dose containment sphere.

Cystic fibrosis

Cystic fibrosis is an autosomal recessive, monogenetic disorder caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. The gene defect was first described 25 years ago and much progress has been made since then in our understanding of how CFTR mutations cause disease and how this can be addressed therapeutically. CFTR is a transmembrane protein that transports ions across the surface of epithelial cells. CFTR dysfunction affects many organs; however, lung disease is responsible for the vast majority of morbidity and mortality in patients with cystic fibrosis. Prenatal diagnostics, newborn screening and new treatment algorithms are changing the incidence and the prevalence of the disease. Until recently, the standard of care in cystic fibrosis treatment focused on preventing and treating complications of the disease; now, novel treatment strategies directly targeting the ion channel abnormality are becoming available and it will be important to evaluate how these treatments affect disease progression and the quality of life of patients. In this Primer, we summarize the current knowledge, and provide an outlook on how cystic fibrosis clinical care and research will be affected by new knowledge and therapeutic options in the near future. For an illustrated summary of this Primer, visit: http://go.nature.com/4VrefN.

Therapeutic options for hydrating airway mucus in cystic fibrosis

BACKGROUND

In cystic fibrosis (CF), genetic mutations in the CF transmembrane conductance regulator (CFTR) gene cause reduced chloride efflux from ciliated airway epithelial cells. This results in a reduction in periciliary liquid (PCL) depth of the airway surface liquid due to associated reduced water efflux. PCL layer dehydration reduces mucociliary clearance (MCC), leading to airway obstruction (reduced airflow and inflammation due to pathogen invasion) with mucus plug formation.

SUMMARY

Rehydrating mucus increases MCC. Mucus hydration can be achieved by direct hydration (administering osmotic agents to set up an osmotic gradient), using CFTR modulators to correct dysfunctional CFTR, or it can be achieved pharmacologically (targeting other ion channels on airway epithelial cells). Key Messages: The molecular mechanisms of several therapies are discussed in the context of pre-clinical and clinical trial studies. Currently, only the osmotic agent 7% hypertonic saline and the CFTR 'potentiator' VX-770 (ivacaftor) are used clinically to hydrate mucus. Emerging therapies include the osmotic agent mannitol (Bronchitol), the intracellular Ca(2+)-raising agent Moli1901/lancovutide, the CFTR potentiator sildenafil [phosphodiesterase type 5 (PDE5) inhibitor] and the CFTR 'corrector' VX-809 (lumacaftor). Other CFTR correctors (e.g. 'chemical chaperones') are also showing pre-clinical promise.

Children and young adults with CF in the USA have better lung function compared with the UK

BACKGROUND

People with cystic fibrosis (CF) are managed differently in the USA and UK providing an opportunity to learn from differences in practice patterns.

OBJECTIVES

To compare cross-sectional demographics, practice patterns and clinical outcomes between US and UK CF patients.

METHODS

This was a cross-sectional study using 2010 data from patients in the US Cystic Fibrosis Foundation and the UK Cystic Fibrosis patient registries. The a priori outcome measures of interest were lung function and nutritional status. Descriptive statistics and two sample comparisons were performed. Stratification and multivariable linear regression were used to adjust for confounding.

RESULTS

The study cohort included 13 777 children and 11 058 adults from the USA and 3968 children and 3965 adults from the UK. In children, mean body mass index centiles were similar. Lung function (FEV1 and FVC% predicted) was significantly higher in US patients ages 6-25 years of age. In a regression model adjusted for only age, FEV1% predicted was on average 3.31% of predicted (95% CI 2.65 to 3.96) higher in the USA compared with the UK. When adjusted for age, age at diagnosis, gender, pancreatic insufficiency and genotype, FEV1% predicted was on average 3.03% of predicted (95% CI 2.37 to 3.69) higher in the USA compared with the UK These differences persisted despite adjustment for possible confounders. Hypertonic saline and dornase alfa were much more commonly prescribed in US children.

CONCLUSIONS

Children and young adults with CF have better lung function in the USA compared with the UK despite similar nutritional status.

Efficacy and adverse effects of drugs used to treat adult cystic fibrosis

INTRODUCTION

Cystic fibrosis (CF) is an autosomal recessive disease and is the most commonly seen monogenetic disease in Caucasians. The disease has various manifestations resulting from the abnormal thick secretions, most common being chronic lung infection and airway obstruction. Many new promising drugs have appeared on the horizon over the years. This review here is an attempt to bring together the various treatments being used to prolong and enhance the quality of life of CF patients.

AREAS COVERED

A literature review of published as well as ongoing clinical trials, meta-analysis and systematic reviews regarding the drugs used in CF management was carried out using PubMed and Ovid databases.

EXPERT OPINION

New concepts have been formed and some positive results in this direction have already led to the approval of cystic fibrosis transmembrane conductance regulator potentiator drug. Gene therapy and stem cell therapy are under development. The current therapies such as dornase alfa and pancreatic enzymes targeting the symptoms continue to evolve as they play an important complementary role. Development of new simple and cost-effective markers, which help assess the efficacy and safety of these constantly emerging new drugs, is also being investigated.

European Cystic Fibrosis Society Standards of Care: Best Practice guidelines

Specialised CF care has led to a dramatic improvement in survival in CF: in the last four decades, well above what was seen in the general population over the same period. With the implementation of newborn screening in many European countries, centres are increasingly caring for a cohort of patients who have minimal lung disease at diagnosis and therefore have the potential to enjoy an excellent quality of life and an even greater life expectancy than was seen previously. To allow high quality care to be delivered throughout Europe, a landmark document was published in 2005 that sets standards of care. Our current document builds on this work, setting standards for best practice in key aspects of CF care. The objective of our document is to give a broad overview of the standards expected for screening, diagnosis, pre-emptive treatment of lung disease, nutrition, complications, transplant/end of life care and psychological support. For comprehensive details of clinical care of CF, references to the most up to date European Consensus Statements, Guidelines or Position Papers are provided in Table 1. We hope that this best practice document will be useful to clinical teams both in countries where CF care is developing and those with established CF centres.

Recent advances in the management of cystic fibrosis

Cystic fibrosis is a disease that still causes a reduced life expectancy. The treatment burden remains high for affected individuals with often a combination of multiple oral and inhaled medications, as well as physiotherapy, required on a daily basis. In this article, we look at an overview of the pathogenesis, how this might lead to treatment options and look at some of the available new therapies, all in the aim of increasing life expectancy and reducing treatment burden.

Inhaled mannitol for non-cystic fibrosis bronchiectasis: a randomised, controlled trial

RATIONALE

Bronchiectasis is characterised by excessive production of mucus and pulmonary exacerbations. Inhaled osmotic agents may enhance mucociliary clearance, but few long-term clinical trials have been conducted.

OBJECTIVES

To determine the impact of inhaled mannitol on exacerbation rates in patients with non-cystic fibrosis (CF) bronchiectasis. Secondary endpoints included time to first exacerbation, duration of exacerbations, antibiotic use for exacerbations and quality of life (QOL) (St George's Respiratory Questionnaire, SGRQ).

METHODS

Patients with non-CF bronchiectasis and a history of chronic excess production of sputum and ≥2 pulmonary exacerbations in the previous 12 months were randomised (1:1) to 52 weeks treatment with inhaled mannitol 400 mg or low-dose mannitol control twice a day. Patients were 18-85 years of age, baseline FEV1 ≥40% and ≤85% predicted and a baseline SGRQ score ≥30.

MAIN RESULTS

461 patients (233 in the mannitol and 228 in the control arm) were treated. Baseline demographics were similar in the two arms. The exacerbation rate was not significantly reduced on mannitol (rate ratio 0.92, p=0.31). However, time to first exacerbation was increased on mannitol (HR 0.78, p=0.022). SGRQ score was improved on mannitol compared with low-dose mannitol control (-2.4 units, p=0.046). Adverse events were similar between groups.

CONCLUSIONS

Mannitol 400 mg inhaled twice daily for 12 months in patients with clinically significant bronchiectasis did not significantly reduce exacerbation rates. There were statistically significant improvements in time to first exacerbation and QOL. Mannitol therapy was safe and well tolerated.

TRIAL REGISTRATION NUMBER

NCT00669331.

Improving the efficacy of inhaled drugs in cystic fibrosis: challenges and emerging drug delivery strategies

Cystic fibrosis (CF) is the most common autosomal recessive disease in Caucasians associated with early death. Although the faulty gene is expressed in epithelia throughout the body, lung disease is still responsible for most of the morbidity and mortality of CF patients. As a local delivery route, pulmonary administration represents an ideal way to treat respiratory infections, excessive inflammation and other manifestations typical of CF lung disease. Nonetheless, important determinants of the clinical outcomes of inhaled drugs are the concentration/permanence at the lungs as well as the ability of the drug to overcome local extracellular and cellular barriers. This review focuses on emerging delivery strategies used for local treatment of CF pulmonary disease. After a brief description of the disease and formulation rules dictated by CF lung barriers, it describes current and future trends in inhaled drugs for CF. The most promising advanced formulations are discussed, highlighting the advantages along with the major challenges for researchers working in this field.

A high-affinity peptide for nicotinic acetylcholine receptor-α1 and its potential use in pulmonary drug delivery

In pulmonary drug delivery, the ability of an affinity molecule to bind to lung epithelium may prolong retention of therapeutic molecules within the lung and consequently yield higher overall bioavailability. To this end, we screened a library of structurally constrained peptides ('aptides') using phage-display technology and identified a high-affinity aptide for the mouse nicotinic acetylcholine receptor-α1 (nAChR-α1). The isolated aptide (APTnAChR-α1) bound to its target protein with high affinity (Kd=47nM). Alexa 488-labeled APTnAChR-α1 showed preferential binding to nAChR-α1-positive mouse lung epithelial cells and mouse muscle cells. Furthermore, the aptide exhibited substantial binding in nAChR-α1-positive tissue sections of muscle, trachea and lung, but not in liver, kidney or spleen tissues, which are nAChR-α1-negative. In an in vivo experiment, a high-intensity fluorescence signal was observed in the entire lung up to 50h after tracheal injection of Cy5.5-APTnAChR-α1, whereas most of the fluorescence signal from a Cy5.5-labeled scrambled peptide washed out within 20h after injection. Taken together, these results indicate that the high-affinity peptide for nAChR-α1 identified here bound tightly to lung epithelium and thus exhibited a long residence time in this tissue, suggesting that the peptide could be used for pulmonary delivery of active pharmaceuticals.

Factors influencing quality of life and disease severity in Hungarian children and young adults with cystic fibrosis

Background

The aim of our study was to evaluate factors affecting cystic fibrosis (CF) patients’ health-related quality of life (HRQoL) and to assess the level of agreement on HRQol between children and their parents.

Methods

Fifty-nine patients (mean age: 14.03 ± 4.81 years) from 5 Hungarian CF centres completed the survey. HRQoL was measured using The Cystic Fibrosis Questionnaire-Revised (CFQ-R). Parents were asked to fill out a questionnaire about their smoking habits, educational level and history of chronic illness. Disease severity was assessed using the physician-reported Shwachman-Kulczycki (SK) score system. Spirometry, Body Mass Index (BMI) percentile (pc), hospitalisation and Pseudomonas aeruginosa (PA) infection were examined as physiologic parameters of CF, and the impact of these factors on HRQoL was assessed. A multivariate regression analysis was performed to identify the most important factors affecting HRQoL. The level of significance was set to 0.05.

Results

Passive smoking and parental educational level and chronic diseases status did not have a significant impact on the patients’ HRQoL (p > 0.05). Significantly lower SK scores and spirometry values were found in low BMI pc patients (p < 0.001), in hospitalised (p < 0.01) and in PA-infected patients (p < 0.01), than in the adequate-weight, non-hospitalised and PA culture-negative subgroup. Lower CFQ-R scores were detected in hospitalised patients than in non-hospitalised patients in their Physical functioning domain. PA-infected patients had HRQoL scores that were significantly worse in the Body image (p < 0.01) and Respiratory symptoms (p < 0.05) domains than the PA culture-negative patients. Patients with a low BMI pc (<25^th BMI pc) had significantly lower scores in the Eating, Body image and Treatment burden domains, than the adequate-weight patients (>25^th BMI pc) (p < 0.01). A strong child–parent agreement was found in the Physical functioning domain (r = 0.77, p < 0.01).

Conclusions

Passive smoking, parental educational level and chronic diseases of parents do not affect the HRQoL of CF patients. In contrast, hospitalisation, PA infection and malnutrition have a significant and negative impact on patients’ HRQoL and the clinical severity of the disease. Parents and children were consistent in their scoring of symptoms and behaviours that were observable.

Emerging drugs for cystic fibrosis

INTRODUCTION

Cystic fibrosis is an autosomal recessive disease, which is the result of a genetic defect in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Pulmonary disease accounts for over 90% of the morbidity and mortality associated with the disease. Conventionally, CF treatment has focused on symptomatic therapy.

AREAS COVERED

In the past, the emphasis for the development of CF therapeutics has previously been on addressing complications of the manifestations rather than on the underlying disease process. However, in the past few decades there has been a paradigm shift with new attention on the underlying biological mechanisms and therapies targeted at curing the disease rather than simply controlling it. This review summarizes the current CF therapeutics pipeline. These developing therapies include CFTR gene therapy, CFTR pharmacotherapeutics, osmotically active agents and anti-inflammatory therapies, as well as novel inhaled antibiotics.

EXPERT OPINION

The CF therapeutics pipeline currently holds great promise both for novel therapies directly targeting the underlying biological mechanisms of CFTR dysfunction and new symptomatic therapies. While CFTR-directed therapy has the highest potential to improve patients' outcome, it is important to continue to develop better treatment options for all aspects of CF lung disease.

Inspiratory flows and volumes in subjects with cystic fibrosis using a new dry powder inhaler device

Introduction:

Drug inhalation via a dry-powder inhaler (DPI) is a convenient, time efficient alternative to nebulizers in the treatment of cystic fibrosis (CF). Efficient drug administration via DPIs depends on the device resistance and adequate (≥ 45L/min) inspiratory flows and volumes generated by individuals. Dry-powder mannitol is delivered using a RS01 breath-actuated device developed by Plastiape, for Pharmaxis. The study aim was to determine in vivo if CF patients’ inspiratory flows and volumes are adequate to use the RS01 DPI device.

Materials and Methodology:

An open, non-interventional study; enrolled 25 CF subjects, aged ≥ 6 years with FEV1 ≥ 30 to < 90‰ predicted. Inspiratory flows and volumes were measured when subjects inhaled in a controlled manner through the RS01 device in series with a spirometer.

Results:

The mean inspiratory volume (IV) of CF subjects was 1.83L ± 0.97. Their achieved mean ± SD peak inspiratory flow (PIF) was 75.5 ± 27.2L/min. Twenty-three subjects (92%) achieved PIF of > 45L/min with the inhaler device; eighteen of those subjects (78%) had a baseline FEV1 of > 1L.

Conclusion:

Use of the RS01 DPI device allowed adequate inspiratory flow and volume for dispersion of dry-powder mannitol in CF patients.

Mannitol enhances antibiotic sensitivity of persister bacteria in Pseudomonas aeruginosa biofilms

The failure of antibiotic therapies to clear Pseudomonas aeruginosa lung infection, the key mortality factor for cystic fibrosis (CF) patients, is partly attributed to the high tolerance of P. aeruginosa biofilms. Mannitol has previously been found to restore aminoglycoside sensitivity in Escherichia coli by generating a proton-motive force (PMF), suggesting a potential new strategy to improve antibiotic therapy and reduce disease progression in CF. Here, we used the commonly prescribed aminoglycoside tobramycin to select for P. aeruginosa persister cells during biofilm growth. Incubation with mannitol (10-40 mM) increased tobramycin sensitivity of persister cells up to 1,000-fold. Addition of mannitol to pre-grown biofilms was able to revert the persister phenotype and improve the efficacy of tobramycin. This effect was blocked by the addition of a PMF inhibitor or in a P. aeruginosa mutant strain unable to metabolise mannitol. Addition of glucose and NaCl at high osmolarity also improved the efficacy of tobramycin although to a lesser extent compared to mannitol. Therefore, the primary effect of mannitol in reverting biofilm associated persister cells appears to be an active, physiological response, associated with a minor contribution of osmotic stress. Mannitol was tested against clinically relevant strains, showing that biofilms containing a subpopulation of persister cells are better killed in the presence of mannitol, but a clinical strain with a high resistance to tobramycin was not affected by mannitol. Overall, these results suggest that in addition to improvements in lung function by facilitating mucus clearance in CF, mannitol also affects antibiotic sensitivity in biofilms and does so through an active, physiological response.

Growth on mannitol-rich media elicits a genome-wide transcriptional response in Burkholderia multivorans that impacts on multiple virulence traits in an exopolysaccharide-independent manner

In common with other members of the Burkholderia cepacia complex (BCC), Burkholderia multivorans is capable of producing exopolysaccharide (EPS) when grown on certain mannitol-rich media. The significance of the resulting mucoid phenotype and the genome-wide response to mannitol has never been characterized despite its clinical relevance following the approval of a dried-powder preparation of mannitol as an inhaled osmolyte therapy for cystic fibrosis (CF) patients. In the present study we defined the transcriptional response of B. multivorans ATCC 17616, a model genome-sequenced strain of environmental origin, to growth on mannitol-rich yeast extract media (MYEM). EPS-dependent and -independent impact of MYEM on virulence-associated traits was assessed in both strain ATCC 17616 and the CF isolate B. multivorans C1576. Our studies revealed a significant transcriptional response to MYEM encompassing approximately 23 % of predicted genes within the genome. Strikingly, this transcriptional response identified that EPS induction occurs in ATCC 17616 without the upregulation of the bce-I and bce-II EPS gene clusters, despite their pivotal role in EPS biosynthesis. Of approximately 20 differentially expressed putative virulence factors, 16 exhibited upregulation including flagella, ornibactin, oxidative stress proteins and phospholipases. MYEM-grown B. multivorans also exhibited enhanced motility, biofilm formation and epithelial cell invasion. In contrast to these potential virulence enhancements, MYEM-grown B. multivorans C1576 showed attenuated virulence in the Galleria mellonella infection model. All of the observed phenotypic responses occurred independently of EPS production, highlighting the profound impact that mannitol-based growth has on the physiology and virulence of B. multivorans.

Phase 3 randomized study of the efficacy and safety of inhaled dry powder mannitol for the symptomatic treatment of non-cystic fibrosis bronchiectasis

BACKGROUND

Inhaled dry powder mannitol enhanced mucus clearance and improved quality of life over 2 weeks in non-cystic fibrosis bronchiectasis. This study's objective was to investigate the efficacy and safety of dry powder mannitol over 12 weeks.

METHODS

Patients with bronchiectasis confirmed by high-resolution CT (HRCT) scan, aged 15 to 80 years, with FEV1≥50% predicted and ≥1 L participated in a randomized, placebo-controlled, double-blind study. Patients with a negative mannitol provocation test were randomized to inhale 320 mg mannitol (n=231) or placebo (n=112) bid for 12 weeks. To further assess safety, the same mannitol dose/frequency was administered to a patient subset in an open-label extension over 52 weeks. Primary end points were changes from baseline at 12 weeks in 24-h sputum weight and St. George's Respiratory Questionnaire (SGRQ) score.

RESULTS

There was a significant difference of 4.3 g in terms of change in sputum weight over 12 weeks (95% CI, 1.64-7.00; P=.002) between mannitol and placebo; however, this was largely driven by a decrease in sputum weight in the placebo group. This was associated, in turn, with more antibiotic use in the placebo group (50 of 112 [45%]) than in the inhaled mannitol group (85 of 231 [37%]). There was no statistical difference between the groups (P=.304) in total SGRQ score (mannitol, -3.4 points [95% CI, -4.81 to -1.94] vs placebo, -2.1 points [95% CI, -4.12 to -0.09]). In a subgroup study (n=82), patients receiving mannitol showed less small airway mucus plugging on HRCT scan at 12 weeks compared with patients receiving placebo (P=.048). Compliance rates were high, and mannitol was well tolerated with adverse events similar to those of placebo.

CONCLUSION

Because the difference in sputum weights appears to be associated with increased antibiotic use in the placebo group, a larger controlled study is now required to investigate the long-term mannitol effect on pulmonary exacerbations and antibiotic use.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT0027753; URL: www.clinicaltrials.gov.

The cystic fibrosis intestine

The clinical manifestations of cystic fibrosis (CF) result from dysfunction of the cystic fibrosis transmembrane regulator protein (CFTR). The majority of people with CF have a limited life span as a consequence of CFTR dysfunction in the respiratory tract. However, CFTR dysfunction in the gastrointestinal (GI) tract occurs earlier in ontogeny and is present in all patients, regardless of genotype. The same pathophysiologic triad of obstruction, infection, and inflammation that causes disease in the airways also causes disease in the intestines. This article describes the effects of CFTR dysfunction on the intestinal tissues and the intraluminal environment. Mouse models of CF have greatly advanced our understanding of the GI manifestations of CF, which can be directly applied to understanding CF disease in humans.

Acute hyperkalemia associated with inhalation of a potent ENaC antagonist: Phase 1 trial of GS-9411

BACKGROUND

Inhaled epithelial sodium channel (ENaC) blockers are designed to increase airway surface liquid volume, thereby benefiting cystic fibrosis patients. This study evaluated the safety, tolerability, and pharmacokinetics of multiple doses of ENaC blocker GS-9411, in healthy participants.

METHODS

This randomized, double-blind, placebo-controlled, parallel-group, residential, Phase 1 study evaluated inhaled GS-9411 (2.4, 4.8, and 9.6 mg) or placebo, dosed twice daily for 14 days.

RESULTS AND CONCLUSIONS

GS-9411 was well tolerated; 86.1% of treated participants completed dosing (n=31/36). Cough and dizziness (27.8% participants each; most of mild severity) were the most commonly reported adverse events and occurred in both placebo and GS-9411 treatment groups. Arrhythmias were not observed for GS-9411-treated participants, and electrocardiographic changes were not considered clinically significant. Serum potassium levels exceeded the upper limit of normal (>5 mmol/L), 4 hr after the morning dose in GS-9411 (n=16/24) and placebo (n=4/12) treatment groups (38 incidences total). Retesting revealed levels had returned to normal within 2-3 hr. In urine electrolyte analyses, obtained 0-6 hr after the Day 1 morning dose, mean sodium/potassium ratios significantly increased from values 0-6 hr before dosing. Increased urine sodium/potassium ratios corresponded with high urine concentrations of active GS-9411 metabolites, which inhibited sodium reabsorption in the kidney, leading to the observed transient hyperkalemia in these participants. Inhaled GS-9411 was well tolerated except for the emergence of transient clinically significant hyperkalemia; this finding resulted in termination of further clinical development of this drug and will necessitate development of a new generation of ENaC blockers, which provide a sustained improvement in mucociliary clearance, while reducing renal exposure to ENaC blockade. Transient increases in mean urine sodium/potassium ratios appeared to be the first signal of electrolyte imbalances resulting from drug-induced block of ENaC in the kidney. The results of this study strongly suggest that clinical trials of novel ENaC blockers will require intensive measurement of plasma and urine electrolyte levels.

Effect of inhaled dry powder mannitol on mucus and its clearance

Insufficient hydration at the airway surface can make mucus adherent and poorly cleared. Cough, the major mechanism of mucus clearance in disease, is ineffective when mucus is adhesive. Inhaled mannitol creates an osmotic drive for water to move into the airway lumen. The consequent increased hydration of the airway surface decreases the adherence of mucus to the epithelium, facilitates the coupling of mucus and cilia thereby increasing mucus clearance. Inhaled mannitol also promotes effective coughing and stimulates mucociliary clearance. The beneficial effect of mannitol on mucus and its clearance has been demonstrated in patients with asthma, bronchiectasis and cystic fibrosis. Inhaled dry powder mannitol (Bronchitol™) is promising to be an effective treatment for the clearance of retained airway secretions.

New advances in the therapy of non-cystic fibrosis bronchiectasis

Non-cystic fibrosis bronchiectasis remains a common and important respiratory disease to date. It is a chronic pathology and consequently the patients usually require continuous treatment. In recent decades therapies that do not have scientific evidence of their benefits have been commonly used in non-cystic fibrosis bronchiectasis. Cystic fibrosis has provided the experience to extrapolate therapeutic approaches to other bronchiectasis patients. Finally, in the last few years some trials have been carried out specifically in non-cystic fibrosis bronchiectasis which aim to assess the efficacy of some of the treatments which are commonly used but sometimes without clear indication. This review will discuss the recent results from these trials, namely mucoactive, anti-inflammatory and antibiotic therapy. Several trials are ongoing and we hope they will be able to add clarification to the management of these patients.

Efficacy of inhaled ciprofloxacin in the management of non-cystic fibrosis bronchiectasis

Non-cystic fibrosis bronchiectasis (NCFBE), a historically under-recognized chronic respiratory condition, is a significant diagnosis currently experiencing a resurgence of interest in its clinical management. Ciprofloxacin is part of the current armamentarium used in the treatment of the recurrent respiratory tract infections seen in NCFBE. Inhaled ciprofloxacin, a novel method of drug delivery for the fluoroquinolone class, is being actively investigated. The inhaled formulation is designed to enhance drug delivery to the site of infection in the lung while minimizing the risk of systemic toxicity. This review summarizes the pharmacology and pharmacokinetics of ciprofloxacin and the rationale for the development of an inhaled formulation for NCFBE. Preclinical and clinical data regarding current development of inhaled ciprofloxacin formulations is also evaluated. Lastly, the anticipated role of inhaled ciprofloxacin in the management of NCFBE is discussed, including future considerations and potential limitations of therapy.

Cystic fibrosis papers of the year 2012

This paper reviews a personal selection of three potentially important cystic fibrosis (CF) interventional studies that have been published in the 12 month period preceding the November 2012 RSM CF conference. The review highlights the difficulties in the interpretation of outcome measures in CF.

Cystic fibrosis therapeutics: the road ahead

A great deal of excitement and hope has followed the successful trials and US Food and Drug Administration approval of the drug ivacaftor (Kalydeco), the first therapy available that targets the underlying defect that causes cystic fibrosis (CF). Although this drug has currently demonstrated a clinical benefit for a small minority of the CF population, the developmental pathway established by ivacaftor paves the way for other CF transmembrane conductance regulator (CFTR) modulators that may benefit many more patients. In addition to investigating CFTR modulators, researchers are actively developing numerous other innovative CF therapies. In this review, we use the catalog of treatments currently under evaluation with the support of the Cystic Fibrosis Foundation, known as the Cystic Fibrosis Foundation Therapeutics Pipeline, as a platform to discuss the variety of candidate treatments for CF lung disease that promise to improve CF care. Many of these approaches target the individual components of the relentless cycle of airway obstruction, inflammation, and infection characteristic of lung disease in CF, whereas others are aimed directly at the gene defect, or the resulting dysfunctional protein, that instigates this cycle. We discuss how new findings from the laboratory have informed not only the development of novel therapeutics, but also the rationales for their use and the outcomes used to measure their effects. By reviewing the breadth of candidate treatments currently in development, as well as the recent progress in CF therapies reflected by the evolution of the therapeutics pipeline over the past few years, we hope to build upon the optimism and anticipation generated by the recent success of Kalydeco.

Mannitol promotes adherence of an outbreak strain of Burkholderia multivorans via an exopolysaccharide-independent mechanism that is associated with upregulation of newly identified fimbrial and afimbrial adhesins

Burkholderia multivorans, a member of the Burkholderia cepacia complex (Bcc), is an important pathogen of the cystic fibrosis (CF) lung. Mannitol, approved as an inhaled osmolyte therapy for use in CF patients, promotes exopolysaccharide (EPS) production by the Bcc. In the present study, we investigated the role of mannitol-induced EPS in the adherence of B. multivorans. We report that mannitol promoted adherence of two representative B. multivorans strains. However, whilst this enhanced adherence was largely EPS-dependent in an environmental isolate, it was EPS-independent within a CF outbreak strain, suggesting strain-to-strain variation in adhesins. Genome sequencing of the outbreak strain enabled the identification of two distinct loci encoding putative fimbrial and afimbrial adhesins. The putative fimbriae-encoding locus was found to be widely distributed amongst clinical and environmental B. multivorans. In contrast, the locus encoding the putative afimbrial adhesin (of the filamentous haemagglutinin family, FHA) was restricted to clinical isolates. Both loci contributed to biofilm formation and mucin adherence. Furthermore, we report that mannitol promoted expression of both loci, and that the locus encoding the putative FHA-family adhesin is a key determinant of the enhanced adherence observed following growth in mannitol. Our studies provide the first characterization, to our knowledge, of B. multivorans adhesins, and in so doing highlight the strain-dependent role of EPS in the Bcc and the difficulties in assigning phenotypic traits to Bcc EPS due to the wider response to mannitol. Our observations also highlight the need to monitor the microbiological effects of inhaled mannitol therapy in Bcc-infected CF patients.

Pooled analysis of two large randomised phase III inhaled mannitol studies in cystic fibrosis

BACKGROUND

To evaluate safety and efficacy of inhaled mannitol treatment in subgroups of a large global CF population.

METHODS

Data were pooled from two multicentre, double-blind, randomised, controlled, parallel group phase III studies in which 600 patients inhaled either mannitol (400 mg) or control (mannitol 50 mg) twice a day for 26 weeks.

RESULTS

Both the mean absolute change in FEV(1) (mL) and relative change in FEV(1) by % predicted from baseline for mannitol (400 mg) versus control were statistically significant (73.42 mL, 3.56%, both p<0.001). Increases in FEV(1) were observed irrespective of rhDNase use. Significant improvements in FEV1 occurred in adults but not children (6-11) or adolescents (aged 12-17). Pulmonary exacerbation incidence was reduced by 29% (p=0.039) in the mannitol (400 mg) group.

CONCLUSIONS

Sustained six-month improvements in lung function and decreased pulmonary exacerbation incidence indicate that inhaled mannitol is an important additional drug in the treatment of CF.

Fluoroquinolones in the treatment of bronchopulmonary disease in cystic fibrosis

Fluoroquinolones are commonly used to treat lung infections in patients with cystic fibrosis. These patients are susceptible to lung infection with common bacteria such as Staphylococcus aureus and Haemophilus influenzae, but are also prone to infection by opportunistic bacteria, including Pseudomonas aeruginosa. The good oral bioavailability and broad antimicrobial spectrum of activity, including antipseudomonal properties, make this class of antimicrobial attractive. We review the evidence assessing the use of fluoroquinolones in the context of preventing and eradicating early lung infection and in managing chronic lung infection and pulmonary exacerbations. The safety of fluoroquinolones and the use of newer agents in the class are also discussed.

Progress in cystic fibrosis and the CF Therapeutics Development Network

Cystic fibrosis (CF), the most common life-shortening genetic disorder in Caucasians, affects approximately 70 000 individuals worldwide. In 1998, the Cystic Fibrosis Foundation (CFF) launched the CF Therapeutics Development Network (CF-TDN) as a central element of its Therapeutics Development Programme. Designed to accelerate the clinical evaluation of new therapies needed to fulfil the CFF mission to control and cure CF, the CF-TDN has conducted 75 clinical trials since its inception, and has contributed to studies as varied as initial safety and proof of concept trials to pivotal programmes required for regulatory approval. This review highlights recent and significant research efforts of the CF-TDN, including a summary of contributions to studies involving CF transmembrane conductance regulator (CFTR) modulators, airway surface liquid hydrators and mucus modifiers, anti-infectives, anti-inflammatories, and nutritional therapies. Efforts to advance CF biomarkers, necessary to accelerate the therapeutic goals of the network, are also summarised.