Targeted therapies to improve CFTR function in cystic fibrosis

Cystic fibrosis is the most common genetically determined, life-limiting disorder in populations of European ancestry. The genetic basis of cystic fibrosis is well established to be mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene that codes for an apical membrane chloride channel principally expressed by epithelial cells. Conventional approaches to cystic fibrosis care involve a heavy daily burden of supportive treatments to combat lung infection, help clear airway secretions and maintain nutritional status. In 2012, a new era of precision medicine in cystic fibrosis therapeutics began with the licensing of a small molecule, ivacaftor, which successfully targets the underlying defect and improves CFTR function in a subgroup of patients in a genotype-specific manner. Here, we review the three main targeted approaches that have been adopted to improve CFTR function: potentiators, which recover the function of CFTR at the apical surface of epithelial cells that is disrupted in class III and IV genetic mutations; correctors, which improve intracellular processing of CFTR, increasing surface expression, in class II mutations; and production correctors or read-through agents, which promote transcription of CFTR in class I mutations. The further development of such approaches offers great promise for future therapeutic strategies in cystic fibrosis

Defining the content and delivery of an intervention to Change AdhereNce to treatment in BonchiEctasis (CAN-BE): a qualitative approach incorporating the Theoretical Domains Framework, behavioural change techniques and stakeholder expert panels

BACKGROUND: Low patient adherence to treatment is associated with poorer health outcomes in bronchiectasis. We sought to use the Theoretical Domains Framework (TDF) (a framework derived from 33 psychological theories) and behavioural change techniques (BCTs) to define the content of an intervention to change patients' adherence in bronchiectasis (Stage 1 and 2) and stakeholder expert panels to define its delivery (Stage 3). METHODS: We conducted semi-structured interviews with patients with bronchiectasis about barriers and motivators to adherence to treatment and focus groups or interviews with bronchiectasis healthcare professionals (HCPs) about their ability to change patients' adherence to treatment. We coded these data to the 12 domain TDF to identify relevant domains for patients and HCPs (Stage 1). Three researchers independently mapped relevant domains for patients and HCPs to a list of 35 BCTs to identify two lists (patient and HCP) of potential BCTs for inclusion (Stage 2). We presented these lists to three expert panels (two with patients and one with HCPs/academics from across the UK). We asked panels who the intervention should target, who should deliver it, at what intensity, in what format and setting, and using which outcome measures (Stage 3). RESULTS: Eight TDF domains were perceived to influence patients' and HCPs' behaviours: Knowledge, Skills, Beliefs about capability, Beliefs about consequences, Motivation, Social influences, Behavioural regulation and Nature of behaviours (Stage 1). Twelve BCTs common to patients and HCPs were included in the intervention: Monitoring, Self-monitoring, Feedback, Action planning, Problem solving, Persuasive communication, Goal/target specified:behaviour/outcome, Information regarding behaviour/outcome, Role play, Social support and Cognitive restructuring (Stage 2). Participants thought that an individualised combination of these BCTs should be delivered to all patients, by a member of staff, over several one-to-one and/or group visits in secondary care. Efficacy should be measured using pulmonary exacerbations, hospital admissions and quality of life (Stage 3). CONCLUSIONS: Twelve BCTs form the intervention content. An individualised selection from these 12 BCTs will be delivered to all patients over several face-to-face visits in secondary care. Future research should focus on developing physical materials to aid delivery of the intervention prior to feasibility and pilot testing. If effective, this intervention may improve adherence and health outcomes for those with bronchiectasis in the future

MRSA eradication of newly acquired lower respiratory tract infection in cystic fibrosis

UK cystic fibrosis (CF) guidelines recommend eradication of methicillin-resistant Staphylococcus aureus (MRSA) when cultured from respiratory samples. As there is no clear consensus as to which eradication regimen is most effective, we determined the efficacy of eradication regimens used in our CF centre and long-term clinical outcome. All new MRSA positive sputum cultures (n=37) that occurred between 2000 and 2014 were reviewed. Eradication regimen characteristics and clinical, microbiological and long-term outcome data were collected. Rifampicin plus fusidic acid was the most frequently used regimen (24 (65%) out of 37 patients), with an overall success rate of 79% (19 out of 24 patients). Eradication failure was more likely in patients with an additional MRSA-positive peripheral screening swab (p=0.03) and was associated with worse survival (p=0.04). Our results demonstrate the feasibility and clinical benefits of MRSA eradication. As peripheral colonisation was associated with lower eradication success, strategies combining systemic and topical treatments should be considered to optimise outcomes in CF patients

Treatment adherence and health outcomes in patients with bronchiectasis

BACKGROUND: We aimed to determine adherence to inhaled antibiotics, other respiratory medicines and airway clearance and to determine the association between adherence to these treatments and health outcomes (pulmonary exacerbations, lung function and Quality of Life Questionnaire-Bronchiectasis [QOL-B]) in bronchiectasis after 12 months. METHODS: Patients with bronchiectasis prescribed inhaled antibiotics for Pseudomonas aeruginosa infection were recruited into a one-year study. Participants were categorised as "adherent" to medication (medication possession ratio ≥80% using prescription data) or airway clearance (score ≥80% in the Modified Self-Reported Medication-Taking Scale). Pulmonary exacerbations were defined as treatment with a new course of oral or intravenous antibiotics over the one-year study. Spirometry and QOL-B were completed at baseline and 12 months. Associations between adherence to treatment and pulmonary exacerbations, lung function and QOL-B were determined by regression analyses. RESULTS: Seventy-five participants were recruited. Thirty-five (53%), 39 (53%) and 31 (41%) participants were adherent to inhaled antibiotics, other respiratory medicines, and airway clearance, respectively. Twelve (16%) participants were adherent to all treatments. Participants who were adherent to inhaled antibiotics had significantly fewer exacerbations compared to non-adherent participants (2.6 vs 4, p = 0.00) and adherence to inhaled antibiotics was independently associated with having fewer pulmonary exacerbations (regression co-efficient = -0.51, 95% CI [-0.81,-0.21], p < 0.001). Adherence to airway clearance was associated with lower QOL-B Treatment Burden (regression co-efficient = -15.46, 95% CI [-26.54, -4.37], p < 0.01) and Respiratory Symptoms domain scores (regression co-efficient = -10.77, 95% CI [-21.45; -0.09], p < 0.05). There were no associations between adherence to other respiratory medicines and any of the outcomes tested. Adherence to treatment was not associated with FEV1 % predicted. CONCLUSIONS: Treatment adherence is low in bronchiectasis and affects important health outcomes including pulmonary exacerbations. Adherence should be measured as part of bronchiectasis management and future research should evaluate bronchiectasis-specific adherence strategies

Shortened Lung Clearance Index is a repeatable and sensitive test in children and adults with cystic fibrosis

BACKGROUND: Lung clearance index (LCI) derived from sulfur hexafluoride (SF6) multiple breath washout (MBW) is a sensitive measure of lung disease in people with cystic fibrosis (CF). However, it can be time-consuming, limiting its use clinically. AIM: To compare the repeatability, sensitivity and test duration of LCI derived from washout to 1/30th (LCI1/30), 1/20th (LCI1/20) and 1/10th (LCI1/10) to 'standard' LCI derived from washout to 1/40th initial concentration (LCI1/40). METHODS: Triplicate MBW test results from 30 clinically stable people with CF and 30 healthy controls were analysed retrospectively. MBW tests were performed using 0.2% SF6 and a modified Innocor device. All LCI end points were calculated using SimpleWashout software. Repeatability was assessed using coefficient of variation (CV%). The proportion of people with CF with and without abnormal LCI and forced expiratory volume in 1 s (FEV1) % predicted was compared. Receiver operating characteristic (ROC) curve statistics were calculated. Test duration of all LCI end points was compared using paired t tests. RESULTS: In people with CF, LCI1/40 CV% (p=0.16), LCI1/30 CV%, (p=0.53), LCI1/20 CV% (p=0.14) and LCI1/10 CV% (p=0.25) was not significantly different to controls. The sensitivity of LCI1/40, LCI1/30 and LCI1/20 to the presence of CF was equal (67%). The sensitivity of LCI1/10 and FEV1% predicted was lower (53% and 47% respectively). Area under the ROC curve (95% CI) for LCI1/40, LCI1/30, LCI1/20, LCI1/10 and FEV1% predicted was 0.89 (0.80 to 0.97), 0.87 (0.77 to 0.96), 0.87 (0.78 to 0.96), 0.83 (0.72 to 0.94) and 0.73 (0.60 to 0.86), respectively. Test duration of LCI1/30, LCI1/20 and LCI1/10 was significantly shorter compared with the test duration of LCI1/40 in people with CF (p<0.0001) equating to a 5%, 9% and 15% time saving, respectively. CONCLUSIONS: In this study, LCI1/20 was a repeatable and sensitive measure with equal diagnostic performance to LCI1/40. LCI1/20 was shorter, potentially offering a more feasible research and clinical measure

Comparison of inhaled antibiotics for the treatment of chronic Pseudomonas aeruginosa lung infection in patients with cystic fibrosis: systematic literature review and network meta-analysis

PURPOSE: In Europe, 4 inhaled antibiotics (tobramycin, colistimethate sodium, aztreonam, and levofloxacin) are currently approved for the treatment of chronic Pseudomonas aeruginosa lung infection in patients with cystic fibrosis (CF). Levofloxacin inhalation solution (LIS) is the most recently approved inhaled antibiotic for adult patients with CF. A systematic literature review and Bayesian network meta-analysis (NMA) was conducted to compare the relative short-term (4 weeks) and long-term (24 weeks) outcomes of these inhaled antibiotics versus LIS. METHODS: A systematic literature search was conducted on February 16, 2016, using EMBASE and Medline via OvidSP. All randomized controlled trials comparing any of the aforementioned inhaled antibiotics with 4 or 24 weeks of follow-up were evaluated. NMA was performed for the following outcomes: relative and absolute percent changes from baseline in forced expiratory volume in 1 second (FEV1%) predicted, change in P aeruginosa sputum density, respiratory symptoms score from the CF questionnaire-revised, hospitalization, additional antibiotics use, and study withdrawal rates. RESULTS: Of the 685 articles identified, 7 unique studies were included in the 4 weeks' NMA and 9 unique studies were included in the 24 weeks' NMA. Aztreonam was predicted to result in the greatest numerically increase in FEV1% predicted at 4 weeks, whereas LIS were predicted to be numerically greater than colistimethate sodium, tobramycin inhaled solution (TIS), and tobramycin inhaled powder (TIP). However, all of the 95% credibility intervals (CrIs) of these comparisons included zero. At 24 weeks, none of the treatments was significantly more effective than LIS. The estimates for the mean change from baseline to 24 weeks in relative FEV1% versus LIS was -0.55 (95% CrI, -3.91 to 2.80) for TIS, -2.36 (95% CrI, -7.32 to 2.63) for aztreonam, -2.95 (95% CrI, -10.44 to 4.51) for TIP, and -9.66 (95% CrI, -15.01 to -4.33) for placebo. Compared with LIS, the odds ratio for hospitalization at 24 weeks was 1.92 (95% CrI, 1.01-3.30) for TIS, 2.25 (95% CrI, 1.01-4.34) for TIP, and 3.16 (95% CrI, 1.53-5.78) for placebo, all statistically worse than LIS. P aeruginosa sputum density scores, additional use of antipseudomonal antibiotics, and study withdrawal rates were comparable among all inhaled antibiotics at all times. IMPLICATIONS: Based on this NMA, the analyses for many of the outcomes did not provide significant evidence to indicate that the other approved inhaled antibiotics were more effective than LIS for the treatment of chronic P aeruginosa lung infection in patients with CF. Study withdrawal rates seemed to be comparable among these inhaled antibiotics

Proteomic profile of cystic fibrosis sputum cells in adults chronically infected with Pseudomonas aeruginosa

Lung disease is the main cause of morbidity and mortality in cystic fibrosis (CF), and involves chronic infection and perturbed immune responses. Tissue damage is mediated mostly by extracellular proteases, but other cellular proteins may also contribute to damage through their effect on cell activities and/or release into sputum fluid by means of active secretion or cell death.We employed MudPIT (multidimensional protein identification technology) to identify sputum cellular proteins with consistently altered abundance in adults with CF, chronically infected with Pseudomonas aeruginosa, compared with healthy controls. Ingenuity Pathway Analysis, Gene Ontology, protein abundance and correlation with lung function were used to infer their potential clinical significance.Differentially abundant proteins relate to Rho family small GTPase activity, immune cell movement/activation, generation of reactive oxygen species, and dysregulation of cell death and proliferation. Compositional breakdown identified high abundance of proteins previously associated with neutrophil extracellular traps. Furthermore, negative correlations with lung function were detected for 17 proteins, many of which have previously been associated with lung injury.These findings expand our current understanding of the mechanisms driving CF lung disease and identify sputum cellular proteins with potential for use as indicators of disease status/prognosis, stratification determinants for treatment prescription or therapeutic targets