Riociguat for the treatment of Phe508del homozygous adults with cystic fibrosis

BACKGROUND

Riociguat is a first-in-class soluble guanylate cyclase stimulator for which preclinical data suggested improvements in cystic fibrosis transmembrane conductance regulator (CFTR) function.

METHODS

This international, multicenter, two-part, Phase II study of riociguat enrolled adults with cystic fibrosis (CF) homozygous for Phe508del CFTR. Part 1 was a 28-day, randomized, double-blind, placebo-controlled study in participants not receiving CFTR modulator therapy. Twenty-one participants were randomized 1:2 to placebo or oral riociguat (0.5 mg three times daily [tid] for 14 days, increased to 1.0 mg tid for the subsequent 14 days). The primary and secondary efficacy endpoints were change in sweat chloride concentration and percent predicted forced expiratory volume in 1 second (ppFEV₁), respectively, from baseline to Day 14 and Day 28 with riociguat compared with placebo.

RESULTS

Riociguat did not alter CFTR activity (change in sweat chloride) or lung function (change in ppFEV₁) at doses up to 1.0 mg tid after 28 days. The most common drug-related adverse event (AE) was headache occurring in three participants (21%); serious AEs occurred in one participant receiving riociguat (7%) and one participant receiving placebo (14%). This safety profile was consistent with the underlying disease and the known safety of riociguat for its approved indications.

CONCLUSIONS

The Rio-CF study was terminated due to lack of efficacy and the changing landscape of CF therapeutic development. The current study⁠, within its limits of a small sample size, did not provide evidence that riociguat could be a valid treatment option for CF.

CLINICAL TRIAL REGISTRATION NUMBER

NCT02170025.

Influence of lung transplantation on the essential fatty acid profile in cystic fibrosis

Lung transplantation is assumed to normalize essential fatty acid (EFA) profile in the plasma, described as abnormal in patients with cystic fibrosis (CF). This study sought to evaluate the EFA profile in both the plasma and erythrocyte membrane according to lung status by comparing CF patients with or without a lung transplant. A total of 50 homozygous F508del patients (33 CF patients [CF group] and 17 CF patients with a lung transplant [TX CF group]) were included. In comparison with the CF group, in the plasma, the levels of total n-3, α-linolenic, eicosapentaenoic, and docosahexaenoic acids were higher and the n-6/n-3 ratio was lower in the TX CF group. Yet, these differences were not observed in the erythrocyte membrane. This study supports that lung transplantation improves the EFA profile in the plasma but not in the erythrocyte membrane by means of the different mechanisms suggested in this article.

Identification of Mycobacterium tuberculosis Infection in Infants and Children With Partial Discrimination Between Active Disease and Asymptomatic Infection

Background: Improved diagnostic tests are needed for the early identification of Mycobacterium tuberculosis-infected young children exposed to an active TB (aTB) index case. We aimed to compare the diagnostic accuracy of new blood-based tests to that of the tuberculin skin test (TST) for the identification of all infected children and for a potential differentiation between aTB and latent TB infection (LTBI). Methods: 144 children exposed to a patient with aTB were included, and those who met all inclusion criteria (130/144) were classified in three groups based on results from classical investigations: non-infected (NI: n = 69, 53%, median age 10 months), LTBI (n = 28, 22%, median age 96 months), aTB disease (n = 33, 25%, median age 24 months). The first whole blood assay consisted of a 7-days in vitro stimulation of blood with four different mycobacterial antigens (40 μl/condition), followed by flow cytometric measurement of the proportions of blast cells appearing among lymphocytes as a result of their specific activation. Thresholds of positivity were determined by Receiver Operating Characteristic (ROC) curve analysis (results of NI children vs. children with LTBI/aTB) in order to identify infected children in a first stage. Other cut-offs were determined to discriminate subgroups of infected children in a second step (results from children with aTB/LTBI). Analysis of blood monocytes and dendritic cell subsets was performed on 100 μl of blood for 25 of these children as a second test in a pilot study. Results: Combining the results of the blast-induced CD3⁺ T lymphocytes by Heparin-Binding Haemagglutinin and by Culture Filtrate Protein-10 identified all but one infected children (sensitivity 98.2% and specificity 86.9%, compared to 93.4 and 100% for the TST). Further identification among infected children of those with aTB was best achieved by the results of blast-induced CD8⁺ T lymphocytes by purified protein derivative (sensitivity for localized aTB: 61.9%, specificity 96.3%), whereas high proportions of blood type 2 myeloid dendritic cells (mDC) were a hallmark of LTBI. Conclusions: New blood-based tests requiring a very small volume allow the accurate identification of M. tuberculosis-infected young children among exposed children and are promising to guide the clinical classification of children with aTB or LTBI.

Intrapulmonary percussive ventilation improves lung function in cystic fibrosis patients chronically colonized with Pseudomonas aeruginosa: a pilot cross-over study

High levels of shear stress can prevent and disrupt Pseudomonas aeruginosa biofilm formation in vitro. Intrapulmonary percussive ventilation (IPV) could be used to introduce shear stress into the lungs of cystic fibrosis (CF) patients to disrupt biofilms in vivo. We performed a first-of-its-kind pilot clinical study to evaluate short-term IPV therapy at medium (200 bursts per minute, bpm) and high frequency (400 bpm) as compared to autogenic drainage (AD) on lung function and the behavior of P. aeruginosa in the CF lung in four patients who are chronically colonized by P. aeruginosa. A significant difference between the three treatment groups was observed for both the forced expiratory volume in 1 s (FEV1) and the forced vital capacity (FVC) (p < 0.05). More specifically, IPV at high frequency significantly increased FEV1 and FVC compared to AD (p < 0.05) and IPV at medium frequency (p < 0.001). IPV at high frequency enhanced the expression levels of P. aeruginosa planktonic marker genes, which was less pronounced with IPV at medium frequency or AD. In conclusion, IPV at high frequency could potentially alter the behavior of P. aeruginosa in the CF lung and improve lung function.

TRIAL REGISTRATION

The trail was retrospectively registered at the ISRCTN registry on 6 June 2013, under trial registration number ISRCTN75391385.

Acute Pain Perception During Different Sampling Methods for Respiratory Culture in Cystic Fibrosis Patients

CONTEXT

Reliable identification of lower respiratory tract pathogens is crucial in the management of cystic fibrosis (CF). The multitude of treatments and clinical procedures are a considerable burden and are potentially provoking pain.

OBJECTIVES

As part of another study (NCT02363764), investigating the bacterial yield of three sampling methods, nasal swabs (NSs), cough swabs (CSs), and (induced) sputum samples ([I]SSs), in both expectorating patients (EPs) and non-expectorating patients (NEPs) with CF, the present study aimed to explore the prevalence of respiratory culture sampling-related pain as assessed by self-report within a cohort of children and adults.

METHODS

Literate patients with CF (aged six years or older) completed a questionnaire on pain perception related to the three aforementioned sampling methods (No/Yes; visual analogue scale for pain [VAS-Pain] [0-10 cm]). In addition, patients were asked to rank these methods by their own preference without taking into account the presumed bacterial yield.

RESULTS

In total, 119 questionnaires were returned. In the EPs-group, CS was most frequently (n%; mean VAS-Pain if pain [range]) reported as painful method: overall (n = 101; 12.9%; 1.8 [0.2-4.8]), children (n = 41; 22.0%; 1.4 [0.2-2.7]), and adults (n = 60; 6.7%; 2.5 [0.5-4.8]). Highest pain intensity scores were observed with NS overall (3.0%; 2.4 [0.3-6.2]) and in children (4.9%; 3.3 [0.3-6.2]), but not in adults (1.7%; 0.6 [-]).NEPs-children (n = 17) reported ISS most frequently and as most painful sampling method (17.6%; 2.0 [1.0-4.0]). The only NEP-adult did not perceive pain. NEPs preferred NS > CS > ISS (61.1%, 33.3%, 5.6%, respectively [P = 0.001]) as primary sampling method, whereas EPs preferred SS > NS > CS (65.7%, 26.3%, 8.1%, respectively [P < 0.0001]). Patients' preference for a specific method inversely correlated to pain perception and intensity in EPs (φ = -0.155 [P = 0.007] and ρ = -0.926 [P = 0.008], respectively), but not in NEPs (φ = -0.226 [P = 0.097] and ρ = -0.135 [P = 0.798], respectively).

CONCLUSION

A relatively large range of pain experiences was observed in patients with CF during respiratory culture sampling, which underlines the importance of individual pain assessment. Nevertheless, clinicians can confidently choose the sampling method based on validity over patients' preference.

Respiratory Bacterial Culture Sampling in Expectorating and Non-expectorating Patients With Cystic Fibrosis

Purpose: Different respiratory sampling methods exist to identify lower airway pathogens in patients with cystic fibrosis (CF), of which bronchoalveolar lavage (BAL), and expectorated sputum are considered the "gold standard." Because BAL cannot be repeated limitless, the diagnosis of lower respiratory tract infections in non-expectorating patients is challenging. Other sampling techniques are nasal swab, cough swab, and induced sputum. The purpose of this study (NCT02363764) was to compare concordance between the microbiological yield of nasal swab, cough swab, and expectorated sputum in expectorating patients; nasal swab, cough swab, and induced sputum in non-expectorating patients; nasal swab, cough swab, induced sputum, and BAL in patients requiring bronchoscopy ("BAL-group"); and to determine the clinical value of cough swab in non-expectorating patients with CF. Methods: Microbiological yield detected by these different sampling techniques was compared between and within 105 expectorating patients, 30 non-expectorating patients and BAL-group (n = 39) in a single CF clinic. Specificity, sensitivity, positive (PPV), and negative (NPV) predictive values were calculated. Results: Overall low sensitivity (6.3-58.0%) and wide-ranging predictive values (0.0-100.0%) indicated that nasal swab was not appropriate to detect lower airway pathogens [Pseudomonas aeruginosa (Pa), Staphylococcus aureus (Sa), and Haemophilus influenzae (Hi)] in all three patient groups. Microbiological yield, specificity, sensitivity, PPV, and NPV of cough swab and induced sputum were largely similar in non-expectorating patients and in BAL-group (except sensitivity (0.0%) of induced sputum for Hi in BAL-group). Calculations for Pa and Hi could not be performed for non-expectorating patients because of low prevalence (n = 2 and n = 3, respectively). In expectorating patients, concordance was found between cough swab and expectorated sputum, except for Hi (sensitivity of 40.0%). Conclusion: Our findings suggest that cough swab might be helpful in detecting the presence of some typical CF pathogens in the lower airways of clinically stable patients with CF. However, in symptomatic patients, who are unable to expectorate and who have a negative cough swab and induced sample, BAL should be performed as it currently remains the "gold standard."

Age-Stratified T Cell Responses in Children Infected with Mycobacterium tuberculosis

Tuberculosis (TB) in young children differs from adult TB in that the risk of rapid progression to active TB (aTB) is higher in children than in adults. The reasons for this increased risk are not fully understood. Early differentiation remains difficult between children at risk to develop aTB from those who will remain healthy and develop a latent TB infection (LTBI). Biomarkers to differentiate aTB from LTBI in children, especially in very young children, are urgently needed. To identify M. tuberculosis-specific functional T cell subsets related to clinical manifestations in children, we enrolled 87 children exposed to M. tuberculosis. After standard clinical assessment, the children were classified as aTB, LTBI, or uninfected. Their CD4⁺ T cell cytokine profiles (IFN-γ, TNF-α, IL-2, IL-17) were analyzed at the single-cell level by flow cytometry after stimulation with three mycobacterial antigens, purified protein derivative (PPD), early-secreted-antigenic target-6 (ESAT-6), or heparin-binding hemagglutinin (HBHA). This approach identified age-related discriminative markers between aTB and LTBI. Whereas among the 3- to 15-year-old children, an excellent discrimination between aTB and LTBI was provided by comparing the ratio between the proportions of ESAT-6-induced IFN-γ^single+ and ESAT-6-induced TNF-α^single+CD4⁺ T lymphocytes, this was not the case for children younger than 3 years. By contrast, in this group (<3years), the analysis of HBHA-induced IL-17^single+CD4⁺ T lymphocytes allowed us to identify children with LTBI by the high proportion of this cellular lymphocyte subset, whereas this was not the case for children with aTB. The analysis at the single-cell level of T cell immune responses induced by mycobacterial antigens are, thus, different in infected children younger or older than 3 years of age. HBHA-induced IL-17 production by CD4⁺ T lymphocytes was associated with protection only in children under 3 years who are at high risk for rapid progression to aTB. This suggests that the HBHA-induced IL-17 production by CD4⁺ T lymphocytes is a potential new correlate of protection against M. tuberculosis in humans, and that the distinction between children with LTBI and those with aTB is possible based on age-related diagnostic markers.

What can the CF registry tell us about rare CFTR-mutations? A Belgian study

Background

CFTR2 provides clinical and functional information of the most common CFTR-mutations. Rare mutations (RMs) occur in only a few patients with limited reported clinical data. Their role in CF-disease liability is hardly documented.

Methods

Belgian CF-Registry 2013 data were analyzed to identify CF with at least 1 RM (CF_+RM). Clinical data and sweat chloride of CF_+RM were compared to CF-controls, carrying 2 class 1 to 3 mutations (CF_classic). Disease severity was compared between both groups. To avoid bias in the comparison, transplanted patients were excluded from each group.

Results

Seventy-seven CF_+RM were identified (77/1183 = 6.5%). Sixty-four different RM were detected, of which 21 had not been previously reported. All RMs, corresponding to HGVS (Human Genome Variation Society) nomenclature, were listed in supplementary data.

Seven transplanted CF_+RM were excluded for further analysis. CF_+RM had higher age at diagnosis [median (IQR)] [3.7 y (0.3–18.3) vs. 0.3y (0.1–2,0) (p < 0.0001)], lower sweat chloride [96 mmol/L (64–107) vs. 104 mmol/L (97–115) (p < 0.0001)], higher FEV₁%pred [77%pred (58–96) vs. 68%pred (48–86) (p = 0.017)], were less frequently pancreatic insufficient [56% vs. 98% (p < 0.0001)], Pseudomonas aeruginosa colonized [24% vs. 44% (p = 0.0093)] and needed fewer IV antibiotics [36% vs. 51% (p = 0.041)] than CF_classic. However, a wide spectrum of disease severity was seen amongst CF_+RM.

Conclusions

CF-patients with a RM cover 6.5% of the Belgian CF-population. Rare mutations can be found in severely ill patients, but more often in late diagnosed, pancreatic sufficient patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s13023-017-0694-1) contains supplementary material, which is available to authorized users.

Investigation of Saliva as an Alternative to Plasma Monitoring of Voriconazole

BACKGROUND AND OBJECTIVES

Therapeutic drug monitoring (TDM) of voriconazole is increasingly being implemented in clinical practice. However, as blood sampling can be difficult in paediatric and ambulatory patients, a non-invasive technique for TDM is desirable. The aim of this study was to compare the pharmacokinetics of voriconazole in saliva with the pharmacokinetics of unbound and total voriconazole in plasma in order to clinically validate saliva as an alternative to plasma in voriconazole TDM.

METHODS

In this pharmacokinetic study, paired plasma and saliva samples were taken at steady state in adult haematology and pneumology patients treated with voriconazole. Unbound and bound plasma voriconazole concentrations were separated using high-throughput equilibrium dialysis. Voriconazole concentrations were determined with liquid chromatography-tandem mass spectrometry. Pharmacokinetic parameters were calculated using log-linear regression.

RESULTS

Sixty-three paired samples were obtained from ten patients (seven haematology and three pneumology patients). Pearson's correlation coefficients (R values) for saliva versus unbound and total plasma voriconazole concentrations showed a very strong correlation, with values of 0.970 (p < 0.001) and 0.891 (p < 0.001), respectively. Linear mixed modelling revealed strong agreement between voriconazole concentrations in saliva and unbound plasma voriconazole concentrations, with a mean bias of -0.03 (95 % confidence interval -0.14 to 0.09; p = 0.60). For total concentrations below 10 mg/L, the mean ratio of saliva to total plasma voriconazole concentrations was 0.51 ± 0.08 (n = 63), which did not differ significantly (p = 0.76) from the unbound fraction of voriconazole in plasma of 0.49 ± 0.03 (n = 36).

CONCLUSIONS

Saliva can serve as a reliable alternative to plasma in voriconazole TDM, and it can easily be implemented in clinical practice.

The ciliopathy-associated CPLANE proteins direct basal body recruitment of intraflagellar transport machinery

Cilia use microtubule-based intraflagellar transport (IFT) to organize intercellular signaling. Ciliopathies are a spectrum of human diseases resulting from defects in cilia structure or function. The mechanisms regulating the assembly of ciliary multiprotein complexes and the transport of these complexes to the base of cilia remain largely unknown. Combining proteomics, in vivo imaging and genetic analysis of proteins linked to planar cell polarity (Inturned, Fuzzy and Wdpcp), we identified and characterized a new genetic module, which we term CPLANE (ciliogenesis and planar polarity effector), and an extensive associated protein network. CPLANE proteins physically and functionally interact with the poorly understood ciliopathy-associated protein Jbts17 at basal bodies, where they act to recruit a specific subset of IFT-A proteins. In the absence of CPLANE, defective IFT-A particles enter the axoneme and IFT-B trafficking is severely perturbed. Accordingly, mutation of CPLANE genes elicits specific ciliopathy phenotypes in mouse models and is associated with ciliopathies in human patients.

The clinical benefits of long-term supplementation with omega-3 fatty acids in cystic fibrosis patients - A pilot study

Effectiveness of omega-3 supplementation in cystic fibrosis (CF) remains controversial. This study sought to evaluate clinical status, exercise tolerance, inflammatory parameters, and erythrocyte fatty acid profile after 1 year of oral omega-3 supplementation in CF patients. Fifteen ΔF508-homozygous patients undergoing chronic azithromycin were randomized to receive omega-3 fish oil supplementation at a dose of 60mg/Kg/day or placebo. In comparison with the previous year, in the supplemented group, the number of pulmonary exacerbations decreased at 12 months (1.7 vs. 3.0, p<0.01), as did the duration of antibiotic therapy (26.5 days vs. 60.0 days, p<0.025). Supplementation significantly increased the levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) as early as <3 months of administration, with concomitant decreases in arachidonic acid (AA) levels. This pilot study suggests that long-term omega-3 supplementation offers several clinical benefits as to the number of exacerbations and duration of antibiotic therapy in CF patients.

Gastric emptying and gastro-oesophageal reflux in children with cystic fibrosis

BACKGROUND

Gastro-oesophageal reflux (GOR) is common in patients with cystic fibrosis (CF). The aim of this study was to investigate the relationship between gastric emptying (GE) and GOR in children with CF.

METHODS

Multichannel intraluminal impedance-pH monitoring (MII-pH) to measure GOR and GE breath test (GEBT) to measure GE were performed in 28 children with symptoms suggestive for GOR disease (GORD) (group 1). GEBT was performed in another 28 children with/without GOR symptoms who agreed to undergo GEBT but not MII-pH (group 2).

RESULTS

In group 1, we found increased acid GOR (AGOR) in 46.4% and delayed GE (DGE) in 21.4% but no relationship between increased AGOR and DGE. There was no DGE in group 2. We found DGE in 10.7% and rapid GE in 12.5% of the whole group.

CONCLUSIONS

Almost half of the children with CF and symptoms suggestive for GORD have increased AGOR and almost a quarter has DGE. However, there was no relation between GOR and GE.

Increase in ventilated air spaces after eradication of chronic methicillin-resistant Staphylococcus aureus infection in cystic fibrosis patients

Effective microbiogical eradication of methicillin-resistant Staphylococcus aureus (MRSA) in patients with cystic fibrosis (CF) can be obtained, but its effect is not always clear-cut in terms of spirometric indices. The aim of this observational prospective cohort study was to study the potential effect of eradication of chronic MRSA infection on lung function including ventilation distribution. Six CF patients, chronically colonized with MRSA (median age: 21 years (range 14-46); median FEV1: 76 (95%CI 58-98)%pred) were successfully eradicated using oral rifampicin and fusidic acid in combination with topical decolonization measures. Lung function and multiple breath washout test were performed at the start and at the end of the eradication protocol and after an average follow-up period of 7·5±1·5(SD) months. One patient cultured MRSA again 4 months after successful eradication. All patients reported reduced sputum production and viscosity. By the end of the follow-up period, there was an increase in ventilated FRCMBW and no change in plethysmographic FRCPL. This resulted in a significant decrease of trapped air by half a litre (from 579 to 40 ml; P = 0·013). Lung clearance index (LCI) also showed a small but significant decrease (from 7·2 to 6·7; P = 0·014) after eradication of MRSA. We conclude that MRSA eradication can be successful, also in terms of recruitment of previously unventilated air spaces, potentially due to reduced sputum production and/or viscosity.

Quantitative bone ultrasound at the distal radius in adults with cystic fibrosis

It is of clinical importance to identify bone disease related to cystic fibrosis (CF) early in its course to allow therapeutic interventions that optimize bone health. To test the technical (precision) and clinical (percentage of abnormal results, correlation with clinical parameters) performance of a commercial quantitative ultrasound apparatus for radial measurements, speed of sound (SOS) was measured at the distal third of the left radius with the Omnisense 7000p apparatus (Sunlight Medical, Tel-Aviv, Israel) in a group of young adult CF patients with regular follow-up at the Brussels and Ghent University Hospital. Sixty-three (37 males) CF patients at a median (range) age of 23.5 y (18.1-39.9) were included. SOS, SOS z-score and SOS t-score were respectively 4017 ± 97 m/s, -0.31 ± 0.74 and -0.60 ± 0.78 in males and 4086 ± 97 m/s, -0.19 ± 0.75 and -0.51 ± 0.95 in females. Mean SOS t-score was significantly lower compared with the manufacturer's reference data for males (p < 0.0001) and females (p = 0.01). SOS z- and t-scores correlated with weight z-score and body mass index z-score in females. No significant correlation was found between SOS and forced expiratory volume in 1 s (%). Neither diabetes mellitus nor liver disease was found to influence SOS. Radial quantitative ultrasound has a precision of 0.55%. The SOS is in the low normal range in 14% of CF patients and is influenced by weight in female patients, but not by the severity of the lung disease.

Pulmonary disease in cystic fibrosis: assessment with chest CT at chest radiography dose levels

PURPOSE

To investigate a computed tomographic (CT) protocol with iterative reconstruction at conventional radiography dose levels for the assessment of structural lung abnormalities in patients with cystic fibrosis ( CF cystic fibrosis ).

MATERIALS AND METHODS

In this institutional review board-approved study, 38 patients with CF cystic fibrosis (age range, 6-58 years; 21 patients <18 years and 17 patients >18 years) underwent investigative CT (at minimal exposure settings combined with iterative reconstruction) as a replacement of yearly follow-up posteroanterior chest radiography. Verbal informed consent was obtained from all patients or their parents. CT images were randomized and rated independently by two radiologists with use of the Bhalla scoring system. In addition, mosaic perfusion was evaluated. As reference, the previous available conventional chest CT scan was used. Differences in Bhalla scores were assessed with the χ(2) test and intraclass correlation coefficients ( ICC intraclass correlation coefficient s). Radiation doses for CT and radiography were assessed for adults (>18 years) and children (<18 years) separately by using technical dose descriptors and estimated effective dose. Differences in dose were assessed with the Mann-Whitney U test.

RESULTS

The median effective dose for the investigative protocol was 0.04 mSv (95% confidence interval [ CI confidence interval ]: 0.034 mSv, 0.10 mSv) for children and 0.05 mSv (95% CI confidence interval : 0.04 mSv, 0.08 mSv) for adults. These doses were much lower than those with conventional CT (median: 0.52 mSv [95% CI confidence interval : 0.31 mSv, 3.90 mSv] for children and 1.12 mSv [95% CI confidence interval : 0.57 mSv, 3.15 mSv] for adults) and of the same order of magnitude as those for conventional radiography (median: 0.012 mSv [95% CI confidence interval : 0.006 mSv, 0.022 mSv] for children and 0.012 mSv [95% CI confidence interval : 0.005 mSv, 0.031 mSv] for adults). All images were rated at least as diagnostically acceptable. Very good agreement was found in overall Bhalla score ( ICC intraclass correlation coefficient , 0.96) with regard to the severity of bronchiectasis ( ICC intraclass correlation coefficient , 0.87) and sacculations and abscesses ( ICC intraclass correlation coefficient , 0.84). Interobserver agreement was excellent ( ICC intraclass correlation coefficient , 0.86-1).

CONCLUSION

For patients with CF cystic fibrosis , a dedicated chest CT protocol can replace the two yearly follow-up chest radiographic examinations without major dose penalty and with similar diagnostic quality compared with conventional CT.

Ataluren for the treatment of nonsense-mutation cystic fibrosis: a randomised, double-blind, placebo-controlled phase 3 trial

BACKGROUND

Ataluren was developed to restore functional protein production in genetic disorders caused by nonsense mutations, which are the cause of cystic fibrosis in 10% of patients. This trial was designed to assess the efficacy and safety of ataluren in patients with nonsense-mutation cystic fibrosis.

METHODS

This randomised, double-blind, placebo-controlled, phase 3 study enrolled patients from 36 sites in 11 countries in North America and Europe. Eligible patients with nonsense-mutation cystic fibrosis (aged ≥ 6 years; abnormal nasal potential difference; sweat chloride >40 mmol/L; forced expiratory volume in 1 s [FEV1] ≥ 40% and ≤ 90%) were randomly assigned by interactive response technology to receive oral ataluren (10 mg/kg in morning, 10 mg/kg midday, and 20 mg/kg in evening) or matching placebo for 48 weeks. Randomisation used a block size of four, stratified by age, chronic inhaled antibiotic use, and percent-predicted FEV1. The primary endpoint was relative change in percent-predicted FEV1 from baseline to week 48, analysed in all patients with a post-baseline spirometry measurement. This study is registered with ClinicalTrials.gov, number NCT00803205.

FINDINGS

Between Sept 8, 2009, and Nov 30, 2010, 238 patients were randomly assigned, of whom 116 in each treatment group had a valid post-baseline spirometry measurement. Relative change from baseline in percent-predicted FEV1 did not differ significantly between ataluren and placebo at week 48 (-2.5% vs -5.5%; difference 3.0% [95% CI -0.8 to 6.3]; p=0.12). The number of pulmonary exacerbations did not differ significantly between treatment groups (rate ratio 0.77 [95% CI 0.57-1.05]; p=0.0992). However, post-hoc analysis of the subgroup of patients not using chronic inhaled tobramycin showed a 5.7% difference (95% CI 1.5-10.1) in relative change from baseline in percent-predicted FEV1 between the ataluren and placebo groups at week 48 (-0.7% [-4.0 to 2.1] vs -6.4% [-9.8 to -3.7]; nominal p=0.0082), and fewer pulmonary exacerbations in the ataluern group (1.42 events [0.9-1.9] vs 2.18 events [1.6-2.7]; rate ratio 0.60 [0.42-0.86]; nominal p=0.0061). Safety profiles were generally similar for ataluren and placebo, except for the occurrence of increased creatinine concentrations (ie, acute kidney injury), which occurred in 18 (15%) of 118 patients in the ataluren group compared with one (<1%) of 120 patients in the placebo group. No life-threatening adverse events or deaths were reported in either group.

INTERPRETATION

Although ataluren did not improve lung function in the overall population of nonsense-mutation cystic fibrosis patients who received this treatment, it might be beneficial for patients not taking chronic inhaled tobramycin.

FUNDING

PTC Therapeutics, Cystic Fibrosis Foundation, US Food and Drug Administration's Office of Orphan Products Development, and the National Institutes of Health.

The deletion of TonB-dependent receptor genes is part of the genome reduction process that occurs during adaptation of Pseudomonas aeruginosa to the cystic fibrosis lung

Chronic Pseudomonas aeruginosa infections are the main cause of morbidity among patients with cystic fibrosis (CF) due to persistent lung inflammation caused by interaction between this bacterium and the immune system. Longitudinal studies of clonally related isolates of a dominant CF clone have indicated that genome reduction frequently occurs during adaptation of P. aeruginosa in the CF lung. In this study, we have evaluated the P. aeruginosa population structure of patients attending the Universitair Ziekenhuis Brussel (UZ Brussel) CF reference center using a combination of genotyping methods. Although the UZ Brussel P. aeruginosa CF population is characterized by the absence of a dominant CF clone, some potential interpatient transmissions could be detected. Interestingly, one of these clones showed deletion of the alternative type I ferripyoverdine receptor gene fpvB. Furthermore, we found that several other TonB-dependent receptors are deleted as well. The genome of one potentially transmissible CF clone was sequenced, revealing large deleted regions including all type III secretion system genes and several virulence genes. Remarkably, a large number of deleted genes are shared between the P. aeruginosa CF clone described in this study and isolates belonging to the dominant Copenhagen CF DK2 clone, suggesting parallel evolution.

Primary ciliary dyskinesia: critical evaluation of clinical symptoms and diagnosis in patients with normal and abnormal ultrastructure

Background

Primary ciliary dyskinesia (PCD) is a rare disorder with variable disease progression. To date, mutations in more than 20 different genes have been found. At present, PCD subtypes are described according to the ultrastructural defect on transmission electron microscopy (TEM) of the motile cilia. PCD with normal ultrastructure (NU) is rarely reported because it requires additional testing. Biallelic mutations in DNAH11 have been described as one cause of PCD with NU.

The aim of our study was to describe the clinical characteristics of a large population of patients with PCD, in relation to the ultrastructural defect. Additionally, we aimed to demonstrate the need for biopsy and cell culture to reliably diagnose PCD, especially the NU subtype.

Methods

We retrospectively analyzed data from 206 patients with PCD. We compared the clinical characteristics, lung function, microbiology and imaging results of 68 patients with PCD and NU to those of 90 patients with dynein deficiencies and 41 patients with central pair abnormalities. In addition, we aimed to demonstrate the robustness of the diagnosis of the NU subtype in cell culture by data from genetic analysis.

Results

PCD with NU comprised 33% (68/206) of all patients with PCD. Compared to other subtypes, patients with PCD and NU had a similar frequency of upper and lower respiratory tract problems, as well as similar lung function and imaging. With the currently widely applied approach, without cell culture, the diagnosis would have been missed in 16% (11/68) of patients with NU. Genetic analysis was performed in 29/68 patients with PCD and NU, and biallelic mutations were found in 79% (23/29) of tested patients.

Conclusions

We reported on the clinical characteristics of a large population of patients with PCD and NU. We have shown that systematic performance of biopsy and cell culture increases sensitivity to detect PCD, especially the subtype with NU.

PCD with NU has similar clinical characteristics as other PCD types and requires biopsy plus ciliogenesis in culture for optimal diagnostic yield.

Eradication of chronic methicillin-resistant Staphylococcus aureus infection in cystic fibrosis patients. An observational prospective cohort study of 11 patients

BACKGROUND

Chronic airway infection with methicillin-resistant Staphylococcus aureus (MRSA) in patients with cystic fibrosis (CF) is an increasing clinical problem, and therapeutic options are limited. Because chronic infection with MRSA can be associated with accelerated decline in lung function, eradication of MRSA is attempted in most CF centres today. The aim of this observational prospective cohort study was to determine whether it is possible to eradicate MRSA from airways of CF patients using prolonged oral antibiotic combination therapy together with topical decolonization measures.

RESULTS

Eleven CF patients, (median age: 9 years (range 1-43); median FEV1: 91%pred (95%CI 74%-100%pred)) who were chronically infected with MRSA, were treated daily for six months with rifampicin and fusidic acid orally. This study did not include a patient control group. Two patients had to switch to an alternative schedule, using rifampicin and clindamycin, due to the resistance pattern of MRSA. Topical decolonization measures were applied to all patients and included mupirocin-containing nasal ointment in both nostrils three times daily for five days and chlorhexidine hair and body wash once daily for five days. Microbiological eradication was achieved in all patients at the end of the six-month eradication protocol, even when significant time (range 18 months to 9 years) had elapsed since initial isolation. In only one patient MRSA reappeared in the six-month follow-up period after the initial study period. Side-effects, like nausea, vomiting and diarrhoea were seen in five out of eleven patients, but did not lead to therapy cessation.

CONCLUSION

Chronic MRSA infection can be eradicated from respiratory tract samples using a six month dual antibiotic regimen and topical MRSA decolonization measures.

In young children, persistent wheezing is associated with bronchial bacterial infection: a retrospective analysis

Background

Young children with persistent wheezing pose a diagnostic and therapeutical challenge to the pediatrician.

We aimed to evaluate bacterial bronchial infection as a possible reason for non response to conventional asthma therapy, and to identify and characterise the predominant pathogens involved.

Methods

We retrospectively analysed microbiological and cytological findings in a selected population of young wheezers with symptoms unresponsive to inhaled corticosteroid (ICS) therapy, who underwent flexible bronchoscopy with bronchoalveolar lavage (BAL). Procedural measures were taken to limit contamination risk and quantitative bacterial culture of BAL fluid (significance cut-off ≥ 10⁴ colony-forming units/ml) was used. Modern microbiological methods were used for detection of a wide panel of pathogens and for characterisation of the bacterial isolates.

Results

33 children aged between 4 and 38 months, without structural anomalies of the conductive airways were evaluated. Significant bacterial BAL cultures were found in 48,5 % of patients. Haemophilus influenzae was isolated in 30,3 %, Streptococcus pneumoniae in 12,1 % and Moraxella catarrhalis in 12,1 %. All H. influenzae isolates were non-encapsulated strains and definitely distinguished from non-haemolytic H. haemolyticus. Respiratory viruses were detected in 21,9 % of cases with mixed bacterial-viral infection in 12,1 %. Cytology revealed a marked neutrophilic inflammation.

Conclusions

Bacterial infection of the bronchial tree is common in persistent preschool wheezers and provides a possible explanation for non response to ICS therapy. Non-typeable H. influenzae seems to be the predominant pathogen involved, followed by S. pneumoniae and M. catarrhalis.