Standards for the care of people with cystic fibrosis; establishing and maintaining health

This is the second in a series of four papers updating the European Cystic Fibrosis Society (ECFS) standards for the care of people with CF. This paper focuses on establishing and maintaining health. The guidance is produced using an evidence-based framework and with wide stakeholder engagement, including people from the CF community. Authors provided a narrative description of their topic and statements, which were more directive. These statements were reviewed by a Delphi exercise, achieving good levels of agreement from a wide group for all statements. This guidance reinforces the importance of a multi-disciplinary CF team, but also describes developing models of care including virtual consultations. The framework for health is reinforced, including the need for a physically active lifestyle and the strict avoidance of all recreational inhalations, including e-cigarettes. Progress with cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapy is reviewed, including emerging adverse events and advice for dose reduction and interruption. This paper contains guidance that is pertinent to all people with CF regardless of age and eligibility for and access to modulator therapy.

Understanding and addressing the needs of people with cystic fibrosis in the era of CFTR modulator therapy

Cystic fibrosis is a multiorgan disease caused by impaired function of the cystic fibrosis transmembrane conductance regulator (CFTR). Since the introduction of the CFTR modulator combination elexacaftor-tezacaftor-ivacaftor (ETI), which acts directly on mutant CFTR to enhance its activity, most people with cystic fibrosis (pwCF) have seen pronounced reductions in symptoms, and studies project marked increases in life expectancy for pwCF who are eligible for ETI. However, modulator therapy has not cured cystic fibrosis and the success of CFTR modulators has resulted in immediate questions about the new state of cystic fibrosis disease and clinical challenges in the care of pwCF. In this Series paper, we summarise key questions about cystic fibrosis disease in the era of modulator therapy, highlighting state-of-the-art research and clinical practices, knowledge gaps, new challenges faced by pwCF and the potential for future health-care challenges, and the pressing need for additional therapies to treat the underlying genetic or molecular causes of cystic fibrosis.

Risk factors for FEV1 decline in European patients with CF: data from the European Cystic Fibrosis Society Patient Registry (ECFSPR)

Aim

To examine the trajectory of forced expiratory volume in 1 s (FEV1) using data from the European Cystic Fibrosis (CF) Society Patient Registry collected from 2008 to 2016, hence the era before highly effective modulator therapy (HEMT). We evaluated risk factors for FEV1 decline.

Methods

The study population included patients with a confirmed diagnosis of CF recorded in the ECFPR (2008–2016). The evolution of FEV1% predicted with age (%FEV1), and the yearly change in %FEV1 were evaluated. Risk factors considered wereCFTRmutation class, gender, age at diagnosis, neonatal screening, meconium ileus, sweat chloride concentration at diagnosis, and country's income level.

Results

We used 199,604 FEV1 recordings from 38,734 patients. The fastest decline was seen during puberty and in patients diagnosed before ten years. Males had a higher %FEV1 but a higher yearly %FEV1 loss between ages 15 and 25. We showed stabilization and even improvement in %FEV1 over age in adults with a class III mutation but a steady decline in patients homozygous for F508del or with both mutations of classes I/II. A faster decline in %FEV1 was found in patients from 'low-income' countries compared to a similar %FEV1 evolution in patients from middle- and high-income countries.

Conclusions

These longitudinal FEV1 data reflect the reality of CF across Europe in the era pre-HEMT and can serve as baseline for comparison with the post-HEMT era. The similar evolution in middle- and high-income countries underlines opportunities for low-income countries.

The effect of CFTR modulators on structural lung disease in cystic fibrosis

Background: Newly developed quantitative chest computed tomography (CT) outcomes designed specifically to assess structural abnormalities related to cystic fibrosis (CF) lung disease are now available. CFTR modulators potentially can reduce some structural lung abnormalities. We aimed to investigate the effect of CFTR modulators on structural lung disease progression using different quantitative CT analysis methods specific for people with CF (PwCF). Methods: PwCF with a gating mutation (Ivacaftor) or two Phe508del alleles (lumacaftor-ivacaftor) provided clinical data and underwent chest CT scans. Chest CTs were performed before and after initiation of CFTR modulator treatment. Structural lung abnormalities on CT were assessed using the Perth Rotterdam Annotated Grid Morphometric Analysis for CF (PRAGMA-CF), airway-artery dimensions (AA), and CF-CT methods. Lung disease progression (0-3 years) in exposed and matched unexposed subjects was compared using analysis of covariance. To investigate the effect of treatment in early lung disease, subgroup analyses were performed on data of children and adolescents aged <18 years. Results: We included 16 modulator exposed PwCF and 25 unexposed PwCF. Median (range) age at the baseline visit was 12.55 (4.25-36.49) years and 8.34 (3.47-38.29) years, respectively. The change in PRAGMA-CF %Airway disease (-2.88 (-4.46, -1.30), p = 0.001) and %Bronchiectasis extent (-2.07 (-3.13, -1.02), p < 0.001) improved in exposed PwCF compared to unexposed. Subgroup analysis of paediatric data showed that only PRAGMA-CF %Bronchiectasis (-0.88 (-1.70, -0.07), p = 0.035) improved in exposed PwCF compared to unexposed. Conclusion: In this preliminary real-life retrospective study CFTR modulators improve several quantitative CT outcomes. A follow-up study with a large cohort and standardization of CT scanning is needed to confirm our findings.

Severity of the S1251N allele in cystic fibrosis is affected by the presence of the F508C variant in cis

BACKGROUND

In cystic fibrosis (CF), genotype-phenotype correlation is complicated by the large number of CFTR variants, the influence of modifier genes, environmental effects, and the existence of complex alleles. We document the importance of complex alleles, in particular the F508C variant present in cis with the S1251N disease-causing variant, by detailed analysis of a patient with CF, with the [S1251N;F508]/G542X genotype and a very mild phenotype, contrasting it to that of four subjects with the [S1251N;F508C]/F508del genotype and classical CF presentation.

METHODS

Genetic differences were identified by Sanger sequencing and CFTR function was quantified using rectal organoids in rectal organoid morphology analysis (ROMA) and forskolin-induced swelling (FIS) assays. CFTR variants were further characterised in CF bronchial epithelial (CFBE) cell lines. The impact of involved amino acid changes in the CFTR 3D protein structure was evaluated.

RESULTS

Organoids of the patient [S1251N;F508] with mild CF phenotype confirmed the CF diagnosis but showed higher residual CFTR function compared to the four others [S1251N;F508C]. CFBE cell lines showed a decrease in [S1251N;F508C]-CFTR function but not in processing when compared to [S1251N;F508]-CFTR. Analysis of the 3D CFTR structure suggested an additive deleterious effect of the combined presence of S1251N and F508C with respect to NBD1-2 dimerisation.

CONCLUSIONS

In vitro and in silico data show that the presence of F508C in cis with S1251N decreases CFTR function without affecting processing. Complex CFTR alleles play a role in clinical phenotype and their identification is relevant in the context of personalised medicine for each patient with CF.

A Comparative Analysis of Pricing and Reimbursement of Cystic Fibrosis Transmembrane Conductance Regulator Modulators in Europe

Objectives: Cystic fibrosis transmembrane conductance regulator (CFTR) modulators, Kalydeco® (ivacaftor), Orkambi® (lumacaftor/ivacaftor) and Symkevi® (tezacaftor/ivacaftor), have substantially improved patients’ lives yet significantly burden healthcare budgets. This analysis aims to compare pricing and reimbursement of aforementioned cystic fibrosis medicines, across European countries.

Methods: Clinical trial registries, national databases, health technology assessment reports and grey literature of Austria, Belgium, Denmark, France, Germany, Ireland, Poland, Spain, Sweden, Switzerland, Netherlands, the United Kingdom were consulted. Publicly available prices, reimbursement statuses, economic evaluations, budget impact analyses and managed entry agreements of CFTR modulators were examined. Results: In Belgium, lowest list prices were observed for Kalydeco® (ivacaftor) and Symkevi® (tezacaftor/ivacaftor) at €417 per defined daily dose (DDD) and €372 per average daily dose (ADD), respectively. Whereas, Switzerland had the lowest price for Orkambi® (lumacaftor/ivacaftor) listed at €309 per DDD. Spain had the highest prices for Kalydeco® (ivacaftor) and Symkevi® (tezacaftor/ivacaftor) at €850 per DDD and €761 per ADD, whereas Orkambi® (lumacaftor/ivacaftor) was most expensive in Poland at €983 per DDD. However, list prices were subject to confidential discounts and likely varied from actual costs. In all countries, these treatments were deemed not to be cost-effective. The annual budget impact of the CFTR modulators varied between countries and depended on factors such as local product prices, size of target population, scope of costs and discounting. However, all modulators were fully reimbursed in ten of the evaluated countries except for Sweden and Poland that, respectively, granted reimbursement to one and none of the therapies. Managed entry agreements were confidential but commonly adopted to address financial uncertainties.

Conclusion: Discrepancies concerning prices, reimbursement and access were detected for Kalydeco® (ivacaftor), Orkambi® (lumacaftor/ivacaftor) and Symkevi® (tezacaftor/ivacaftor) across European countries.

Rectal organoid morphology analysis (ROMA) as a promising diagnostic tool in cystic fibrosis

Diagnosing cystic fibrosis (CF) when sweat chloride is not in the CF range and less than 2 disease-causing CFTR mutations are found requires physiological CFTR assays, which are not always feasible or available. We developed a new physiological CFTR assay based on the morphological differences between rectal organoids from subjects with and without CF. In organoids from 167 subjects with and 22 without CF, two parameters derived from a semi-automated image analysis protocol (rectal organoid morphology analysis, ROMA) fully discriminated CF subjects with two disease-causing mutations from non-CF subjects (p<0.001). ROMA, feasible at all ages, can be centralised to improve standardisation.

Long-term safety and efficacy of tezacaftor-ivacaftor in individuals with cystic fibrosis aged 12 years or older who are homozygous or heterozygous for Phe508del CFTR (EXTEND): an open-label extension study

BACKGROUND

Tezacaftor-ivacaftor is an approved cystic fibrosis transmembrane conductance regulator (CFTR) modulator shown to be efficacious and generally safe and well tolerated over 8-24 weeks in phase 3 clinical studies in participants aged 12 years or older with cystic fibrosis homozygous for the Phe508del CFTR mutation (F/F; study 661-106 [EVOLVE]) or heterozygous for the Phe508del CFTR mutation and a residual function mutation (F/RF; study 661-108 [EXPAND]). Longer-term (>24 weeks) safety and efficacy of tezacaftor-ivacaftor has not been assessed in clinical studies. Here, we present results of study 661-110 (EXTEND), a 96-week open-label extension study that assessed long-term safety, tolerability, and efficacy of tezacaftor-ivacaftor in participants aged 12 years or older with cystic fibrosis who were homozygous or heterozygous for the Phe508del CFTR mutation.

METHODS

Study 661-110 was a 96-week, phase 3, multicentre, open-label study at 170 clinical research sites in Australia, Europe, Israel, and North America. Participants were aged 12 years or older, had cystic fibrosis, were homozygous or heterozygous for Phe508del CFTR, and completed one of six parent studies of tezacaftor-ivacaftor: studies 661-103, 661-106, 661-107, 661-108, 661-109, and 661-111. Participants received oral tezacaftor 100 mg once daily and oral ivacaftor 150 mg once every 12 h for up to 96 weeks. The primary endpoint was safety and tolerability. Secondary endpoints were changes in lung function, nutritional parameters, and respiratory symptom scores; pulmonary exacerbations; and pharmacokinetic parameters. A post-hoc analysis assessed the rate of lung function decline in F/F participants who received up to 120 weeks of tezacaftor-ivacaftor in studies 661-106 (F/F) and/or 661-110 compared with a matched cohort of CFTR modulator-untreated historical F/F controls from the Cystic Fibrosis Foundation Patient Registry. Primary safety analyses were done in all participants from all six parent studies who received at least one dose of study drug during this study. This study was registered at ClinicalTrials.gov (NCT02565914).

FINDINGS

Between Aug 31, 2015, to May 31, 2019, 1044 participants were enrolled in study 661-110 from the six parent studies of whom 1042 participants received at least one dose of study drug and were included in the safety set. 995 (95%) participants had at least one TEAE; 22 (2%) had TEAEs leading to discontinuation; and 351 (34%) had serious TEAEs. No deaths occurred during the treatment-emergent period; after the treatment-emergent period, two deaths occurred, which were both deemed unrelated to study drug. F/F (106/110; n=459) and F/RF (108/110; n=226) participants beginning tezacaftor-ivacaftor in study 661-110 had improvements in efficacy endpoints consistent with parent studies; improvements in lung function and nutritional parameters and reductions in pulmonary exacerbations observed in the tezacaftor-ivacaftor groups in the parent studies were generally maintained in study 661-110 for an additional 96 weeks. Pharmacokinetic parameters were also similar to those in the parent studies. The annualised rate of lung function decline was 61·5% (95% CI 35·8 to 86·1) lower in tezacaftor-ivacaftor-treated F/F participants versus untreated matched historical controls.

INTERPRETATION

Tezacaftor-ivacaftor was generally safe, well tolerated, and efficacious for up to 120 weeks, and the safety profile of tezacaftor-ivacaftor in study 661-110 was consistent with cystic fibrosis manifestations and with the safety profiles of the parent studies. The rate of lung function decline was significantly reduced in F/F participants, consistent with cystic fibrosis disease modification. Our results support the clinical benefit of long-term tezacaftor-ivacaftor treatment for people aged 12 years or older with cystic fibrosis with F/F or F/RF genotypes.

FUNDING

Vertex Pharmaceuticals Incorporated.

Correction of CFTR function in intestinal organoids to guide treatment of cystic fibrosis

RATIONALE

Given the vast number of cystic fibrosis transmembrane conductance regulator (CFTR) mutations, biomarkers predicting benefit from CFTR modulator therapies are needed for subjects with cystic fibrosis (CF).

OBJECTIVES

To study CFTR function in organoids of subjects with common and rare CFTR mutations and evaluate correlations between CFTR function and clinical data.

METHODS

Intestinal organoids were grown from rectal biopsies in a cohort of 97 subjects with CF. Residual CFTR function was measured by quantifying organoid swelling induced by forskolin and response to modulators by quantifying organoid swelling induced by CFTR correctors, potentiator and their combination. Organoid data were correlated with clinical data from the literature.

RESULTS

Across 28 genotypes, residual CFTR function correlated (r²=0.87) with sweat chloride values. When studying the same genotypes, CFTR function rescue by CFTR modulators in organoids correlated tightly with mean improvement in lung function (r²=0.90) and sweat chloride (r²=0.95) reported in clinical trials. We identified candidate genotypes for modulator therapy, such as E92K, Q237E, R334W and L159S. Based on organoid results, two subjects started modulator treatment: one homozygous for complex allele Q359K_T360K, and the second with mutation E60K. Both subjects had major clinical benefit.

CONCLUSIONS

Measurements of residual CFTR function and rescue of function by CFTR modulators in intestinal organoids correlate closely with clinical data. Our results for reference genotypes concur with previous results. CFTR function measured in organoids can be used to guide precision medicine in patients with CF, positioning organoids as a potential in vitro model to bring treatment to patients carrying rare CFTR mutations.

G970R-CFTR Mutation (c.2908G>C) Results Predominantly in a Splicing Defect

In previous work, participants with a G970R mutation in cystic fibrosis transmembrane conductance regulator (CFTR) (c.2908G>C) had numerically lower sweat chloride responses during ivacaftor treatment than participants with other CFTR gating mutations. The objective of this substudy was to characterize the molecular defect of the G970R mutation in vitro and assess the benefit of ivacaftor in participants with this mutation. This substudy assessed sweat chloride, spirometry findings, and nasal potential difference on and off ivacaftor treatment in three participants with a G970R/F508del genotype. Intestinal organoids derived from rectal biopsy specimens were used to assess ivacaftor response ex vivo and conduct messenger RNA splice and protein analyses. No consistent or meaningful trends were observed between on-treatment and off-treatment clinical assessments. Organoids did not respond to ivacaftor in forskolin-induced swelling assays; no mature CFTR protein was detected in Western blots. Organoid RNA analysis demonstrated that 3 novel splice variants were created by G970R-CFTR: exon 17 truncation, exons 13-15 and 17 skipping, and intron 17 retention. Functional and molecular analyses indicated that the c.2908G>C mutation caused a cryptic splicing defect. Organoids lacked an ex vivo response with ivacaftor and supported identification of the mechanism underlying the CFTR defect caused by c.2908G>C. Analysis of CFTR mutations indicated that cryptic splicing was a rare cause of mutation misclassification in engineered cell lines. This substudy used organoids as an alternative in vitro model for mutations, such as cryptic splice mutations that cannot be fully assessed using cDNA expressed in recombinant cell systems.

Cystic fibrosis in the year 2020: A disease with a new face

The autosomal recessive disease cystic fibrosis (CF) was once untreatable and deadly in childhood, but now most patients survive to adulthood. Many countries have instituted CF newborn screening because early diagnosis improves outcome. CF research has greatly intensified following the discovery of the CF transmembrane conductance regulator (CFTR) gene, which has more than 2000 different mutations. For patients with common mutations like F508del, CFTR modulators are life transforming and may even prevent major complications if started early in childhood. For some patients with rare CFTR mutations, a treatment path still needs to be developed. Conclusion: This review provides a general update on CF, including screening and current and future treatment.

Phenotyping of Rare CFTR Mutations Reveals Distinct Trafficking and Functional Defects

Background. The most common CFTR mutation, F508del, presents with multiple cellular defects. However, the possible multiple defects caused by many rarer CFTR mutations are not well studied. We investigated four rare CFTR mutations E60K, G85E, E92K and A455E against well-characterized mutations, F508del and G551D, and their responses to corrector VX-809 and/or potentiator VX-770. Methods. Using complementary assays in HEK293T stable cell lines, we determined maturation by Western blotting, trafficking by flow cytometry using extracellular 3HA-tagged CFTR, and function by halide-sensitive YFP quenching. In the forskolin-induced swelling assay in intestinal organoids, we validated the effect of tagged versus endogenous CFTR. Results. Treatment with VX-809 significantly restored maturation, PM localization and function of both E60K and E92K. Mechanistically, VX-809 not only raised the total amount of CFTR, but significantly increased the traffic efficiency, which was not the case for A455E. G85E was refractory to VX-809 and VX-770 treatment. Conclusions. Since no single model or assay allows deciphering all defects at once, we propose a combination of phenotypic assays to collect rapid and early insights into the multiple defects of CFTR variants.

Assessing gastro-intestinal related quality of life in cystic fibrosis: Validation of PedsQL GI in children and their parents

BACKGROUND

Most patients with cystic fibrosis (CF) suffer from pancreatic insufficiency, leading to fat malabsorption, malnutrition and abdominal discomfort. Until recently, no specific tool was available for assessing gastro-intestinal related quality of life (GI QOL) in patients with CF. As the Horizon2020 project MyCyFAPP aims to improve GI QOL by using a newly designed mobile application, a sensitive and reliable outcome measure was needed. We aimed to study the applicability of the existing child-specific Pediatric Quality of Life Inventory, Gastrointestinal Symptoms Scales and Module (PedsQL GI) in children with CF.

METHODS

A multicenter, prospective observational study was performed in 6 European centers to validate the PedsQL GI in children with CF during 3 months.

RESULTS

In total, 248 children and their parents were included. Within-patient variability of PedsQL GI was low (24.11), and there was reasonable agreement between children and parents (ICC 0.681). Nine of 14 subscales were informative (no ceiling effect). The PedsQL GI and the median scores for 4 subscales were significantly lower in patients compared to healthy controls. Positive associations were found between PedsQL GI and age (OR = 1.044, p = 0.004) and between PedsQL GI and BMI z-score (OR = 1.127, p = 0.036). PedsQL GI correlated with most CFQ-R subscales (r 0.268 to 0.623) and with a Visual Analogue Scale (r = 0.20).

CONCLUSIONS

PedsQL GI is a valid and applicable instrument to assess GI QOL in children with CF. Future research efforts should examine the responsiveness of the CF PedsQL GI to change in the context of clinical interventions and trials.

Lung function evolution in children with old and new type bronchopulmonary dysplasia: a retrospective cohort analysis

Bronchopulmonary dysplasia (BPD) is one of the most important sequelae of premature birth. There is concern that in some patients, lung injuries early in life may have lifelong consequences. In this retrospective observational cohort study, lung function evolution in children with BPD was investigated from childhood to young adulthood. Data from 355 pulmonary function tests (PFT) in 24 patients were analyzed, with a median age at first PFT of 7.6 years and at last PFT 18.2 years. FEV₁ and FEV₁/FVC were below the 5th percentile in respectively 18 and 13/24 patients. Comparing first and last measurement, there was significant worsening in FEV₁ from a mean of 71.3% pred (SD 18.3) to 66.7% pred (SD 21.7) (p < 0.05) and in FEV₁/FVC from 85.4% pred (SD 15.2) to 79.8% pred (SD 17.3) (p = 0.01). Evaluation of the individual lung function changes with linear regression showed deterioration in FEV₁, FVC, and FEV₁/FVC in respectively 17, 13, and 17/24 patients. Total group analysis showed significant deterioration in FEV₁ (- 0.7%/year, p = 0.002) and FEV₁/FVC (- 0.5%/year, p = 0.01). None of the 11 patients born up to 1990 improved in FEV₁ vs 7 of the 13 patients born after 1990 (p = 0.006).Conclusion: This points out to further deterioration of the lung function during childhood in this selected group of children with BPD.What is Known:• Data on longitudinal changes in lung function in children with BPD are scarce.What is New:• In children with BPD at the severe end of the disease spectrum, lung function does not improve over time. On the contrary, in two-thirds of the subjects studied FEV₁and FEV₁/FVC worsen over time.• Lung function evolution towards adulthood was somewhat more favorable in children born after 1990 compared with those born earlier, probably reflecting improvements in neonatal care in subjects with new type BPD.

Defining Polysaccharide Antibody Deficiency: Measurement of Anti-Pneumococcal Antibodies and Anti-Salmonella typhi Antibodies in a Cohort of Patients with Recurrent Infections

BACKGROUND

The correlation between different methods for the detection of pneumococcal polysaccharide vaccine (PPV) responses to diagnose specific polysaccharide antibody deficiency (SAD) is poor and the criteria for defining a normal response lack consensus. We previously proposed fifth percentile (p5) values of PPV responses as a new cutoff for SAD.

OBJECTIVE

To analyze the association of SAD (determined by either World Health Organization (WHO)-standardized ELISA or multiplex bead-based assay) with abnormal response to Salmonella (S.) typhi Vi vaccination in a cohort of patients with recurrent infections.

METHODS

Ninety-four patients with a clinical history suggestive of antibody deficiency received PPV and S. typhi Vi vaccines. Polysaccharide responses to either 3 or 18 pneumococcal serotypes were measured by either the WHO ELISA or a multiplex in-house bead-based assay. Anti-S. typhi Vi IgG were measured by a commercial ELISA kit. Allohemagglutinins (AHA) were measured by agglutination method.

RESULTS

Based on the American Academy of Allergy, Asthma and Immunology (AAAAI) criteria for WHO ELISA, 18/94 patients were diagnosed with SAD and 22/93 based on serotype-specific p5 cutoffs for bead-based assay. The association between the two methods was significant, with 10 subjects showing abnormal response according to both techniques. Abnormal response to S. typhi Vi vaccination was found in 7 patients, 6 of which had SAD. No correlation was found between polysaccharide response and AHA, age, or clinical phenotype.

CONCLUSION

The lack of evidence-based gold standards for the diagnosis of SAD represents a challenge in clinical practice. In our cohort, we confirmed the insufficient correlation between different methods of specific PPV response measurement, and showed that the S. typhi Vi response was not contributive. Caution in the interpretation of results is warranted until more reliable diagnostic methods can be validated.

Isolation of Enterobacteriaceae in airway samples is associated with worse outcome in preschool children with cystic fibrosis

BACKGROUND

Increased abundance of Enterobacteriaceae(EB) in the respiratory microbiome of young CF patients was reported to precede Pseudomonas aeruginosa(PA) colonisation. We explored whether impending PA colonisation can be predicted by growth of EB in routine airway cultures and whether EB contribute to CF lung disease severity.

METHODS

We retrospectively studied the records of 62 children with CF for growth of EB and PA during the first 5 years of life and subsequent best lung function at ages 5-7 and 9-11 years.

RESULTS

At least one EB positive month occurred in 36/62 (58%) patients. Median (IQR) age at first EB isolation was 0.4 (0.2-0.8) years. PA isolation before age 5 was more frequent in the EB positive (23/36, 54%) than in EB negative children (10/26, 38%; p = 0.048). EB isolation preceded PA isolation in 19/23 (83%) cases (p = 0.003). Median (IQRf) FEV₁ at age 5 to 7 years was 105% (94-117) in the EB positive group and 108% (102-115) in the EB negative group (p = 0.154). At age 9-11, FEV₁ was lower in EB positive children (99%(88-105) vs 105%(96-110); p = 0.035). Only PA isolation (p = 0.002) before age 5 years was a significant predictor of FEV₁ at age 5-7 years. Both EB isolation (p = 0.033) and PA isolation (p = 0.023) were predictors of the FEV₁ at age 9-11 years.

CONCLUSION

In preschool children with CF, EB were isolated in just over half of the children. In that subgroup PA isolation was more common. Both EB and PA isolation are associated with worse lung function at later age.

Allele specific repair of splicing mutations in cystic fibrosis through AsCas12a genome editing

Cystic fibrosis (CF) is an autosomal recessive disease caused by mutations in the CFTR gene. The 3272-26A>G and 3849+10kbC>T CFTR mutations alter the correct splicing of the CFTR gene, generating new acceptor and donor splice sites respectively. Here we develop a genome editing approach to permanently correct these genetic defects, using a single crRNA and the Acidaminococcus sp. BV3L6, AsCas12a. This genetic repair strategy is highly precise, showing very strong discrimination between the wild-type and mutant sequence and a complete absence of detectable off-targets. The efficacy of this gene correction strategy is verified in intestinal organoids and airway epithelial cells derived from CF patients carrying the 3272-26A>G or 3849+10kbC>T mutations, showing efficient repair and complete functional recovery of the CFTR channel. These results demonstrate that allele-specific genome editing with AsCas12a can correct aberrant CFTR splicing mutations, paving the way for a permanent splicing correction in genetic diseases.

Nasal potential difference in suspected cystic fibrosis patients with 5T polymorphism

BACKGROUND

5T polymorphism is a CFTR mutation with unclear clinical consequences: the phenotype varies from healthy individuals to Cystic Fibrosis (CF). The aim of this study was to evaluate if nasal potential difference (NPD) and sweat testing correlate with symptoms and CF diagnosis in 5T patients.

METHODS

86 patients with 5T who had undergone NPD measurement, were included (6 homozygous (5T/5T), 41 with a PI-CF causing mutation in trans (5T/PI-CF), 11 with a PS-CF causing mutation in trans (5T/PS-CF) and 28 without a known mutation in trans (5T/?). Data including age, phenotype, sweat chloride and follow up were collected.

RESULTS

33% of the 5T/5T patients had abnormal NPD results, compared to 70% in 5T/PI-CF; 33% in 5T/PS-CF and 29% in 5T/?. The percentage of high or borderline sweat chloride was highest in 5T/PI-CF, and 5T/?, compared to 5T/5T and 5T/PS-CF (91, 96, 80, and 63%, respectively). TGm (number of TG repeats in intron 8) analysis was performed in 21 5T/PI-CF patients. TG11 was associated with lower sweat chloride, lower percentage of abnormal NPD and less progression of symptoms compared to TG12 and TG13.

CONCLUSION

There is much variation in clinical status among 5T patients. All patients in this study with 5T/PS CF, all patients with both normal NPD and sweat test, and most patients with TG11 were stable or improving over time. Therefore, NPD measurement and TGm status aid to assess if a patient is at high risk for developing CF or CFTR-related disease and if specific follow up in a CF center is required.

CFTR activity is enhanced by the novel corrector GLPG2222, given with and without ivacaftor in two randomized trials

BACKGROUND

Several treatment approaches in cystic fibrosis (CF) aim to correct CF transmembrane conductance regulator (CFTR) function; the efficacy of each approach is dependent on the mutation(s) present. A need remains for more effective treatments to correct functional deficits caused by the F508del mutation.

METHODS

Two placebo-controlled, phase 2a studies evaluated GLPG2222, given orally once daily for 29 days, in subjects homozygous for F508del (FLAMINGO) or heterozygous for F508del and a gating mutation, receiving ivacaftor (ALBATROSS). The primary objective of both studies was to assess safety and tolerability. Secondary objectives included assessment of pharmacokinetics, and of the effect of GLPG2222 on sweat chloride concentrations, pulmonary function and respiratory symptoms.

RESULTS

Fifty-nine and 37 subjects were enrolled into FLAMINGO and ALBATROSS, respectively. Treatment-related treatment-emergent adverse events (TEAEs) were reported by 29.2% (14/48) of subjects in FLAMINGO and 40.0% (12/30) in ALBATROSS; most were mild to moderate in severity and comprised primarily respiratory, gastrointestinal, and infection events. There were no deaths or discontinuations due to TEAEs. Dose-dependent decreases in sweat chloride concentrations were seen in GLPG2222-treated subjects (maximum decrease in FLAMINGO: -17.6 mmol/L [GLPG2222 200 mg], p < 0.0001; ALBATROSS: -7.4 mmol/L [GLPG2222 300 mg], p < 0.05). No significant effects on pulmonary function or respiratory symptoms were reported. Plasma GLPG2222 concentrations in CF subjects were consistent with previous studies in healthy volunteers and CF subjects.

CONCLUSIONS

GLPG2222 was well tolerated. Sweat chloride reductions support on-target enhancement of CFTR activity in subjects with F508del mutation(s). Significant improvements in clinical endpoints were not demonstrated. Observed safety results support further evaluation of GLPG2222, including in combination with other CFTR modulators.

FUNDING

Galapagos NV. Clinical trial registration numbers FLAMINGO, NCT03119649; ALBATROSS, NCT03045523.

Antisense oligonucleotide eluforsen improves CFTR function in F508del cystic fibrosis

Background:

Cystic fibrosis (CF) is caused by mutations in the CF transmembrane conductance regulator (CFTR) gene. In this study we assessed the effect of antisense oligonucleotide eluforsen on CFTR biological activity measured by Nasal Potential Difference (NPD) in patients with the most common mutation, F508del-CFTR.

Methods:

This multi-centre, exploratory, open-label study recruited adults with CF homozygous or compound heterozygous for the F508del-CFTR mutation. Subjects received intranasal eluforsen three times weekly for 4 weeks. The primary endpoint was the within-subject change from baseline in total chloride transport (Cl-free+iso), as assessed by NPD. Secondary endpoints included within-subject change from baseline in sodium transport.

Results:

In the homozygous cohort (n = 7; per-protocol population), mean change (90% confidence interval) in Cl-free+iso was −3.0 mV (−6.6; 0.6) at day 15, −4.1 mV (−7.8; −0.4, p = .04) at day 26 (end of treatment) and − 3.7 mV (−8.0; 0.6) at day 47. This was supported by improved sodium transport as assessed by an increase in average basal potential difference at day 26 of +9.4 mV (1.1; 17.7, p = .04). The compound heterozygous cohort (n = 7) did not show improved chloride or sodium transport NPD values. Eluforsen was well tolerated with a favourable safety profile.

Conclusions:

In F508del-CFTR homozygous subjects, repeated intranasal administration of eluforsen improved CFTR activity as measured by NPD, an encouraging indicator of biological activity.

Omalizumab in allergic bronchopulmonary aspergillosis in patients with cystic fibrosis

Background

Allergic bronchopulmonary aspergillosis (ABPA) is a condition characterized by a Th2 response, serum eosinophilia, and increased total serum IgE to Aspergillus fumigatus. ABPA occurs in cystic fibrosis (CF) and asthma. Omalizumab is a humanized recombinant monoclonal antibody against IgE. Previous studies reported borderline results when treating ABPA with omalizumab.

Methods

A retrospective study to investigate the efficacy of omalizumab in the treatment of ABPA in CF patients was conducted at 3 CF centers in Israel and Belgium. Data were obtained from the digital archive. We measured 4 outcome parameters: forced expiratory volume in 1 second, body mass index, pulmonary exacerbations, and steroid sparing.

Results

The database was composed on the records of 9 patients. None of the outcome parameters showed any improvement. A favorable outcome was observed in patients with higher levels of posttreatment total IgE than those with lower levels. CF-related diabetes and male gender showed trends for poorer outcomes.

Conclusion

No benefits were detected on treating ABPA in CF with omlaizumb. Monitoring the total IgE was not helpful. A prospective randomized double-blind study is needed.

Neutrophils from Patients with Primary Ciliary Dyskinesia Display Reduced Chemotaxis to CXCR2 Ligands

Primary ciliary dyskinesia (PCD), cystic fibrosis (CF), and chronic obstructive airway disease are characterized by neutrophilic inflammation in the lungs. In CF and chronic obstructive airway disease, improper functioning of neutrophils has been demonstrated. We hypothesized that the pulmonary damage in PCD might be aggravated by abnormal functioning neutrophils either as a primary consequence of the PCD mutation or secondary to chronic inflammation. We analyzed chemotactic responses and chemoattractant receptor expression profiles of peripheral blood neutrophils from 36 patients with PCD, 21 healthy children and 19 healthy adults. We stimulated peripheral blood monocytes from patients and healthy controls and measured CXCL8 and IL-1β production with ELISA. PCD neutrophils displayed reduced migration toward CXCR2 ligands (CXCL5 and CXCL8) in the shape change, microchamber and microslide chemotaxis assays, whereas leukotriene B4 and complement component 5a chemotactic responses were not significantly different. The reduced response to CXCL8 was observed in all subgroups of patients with PCD (displaying either normal ultrastructure, dynein abnormalities or central pair deficiencies) and correlated with lung function. CXCR2 was downregulated in about 65% of the PCD patients, suggestive for additional mechanisms causing CXCR2 impairment. After treatment with the TLR ligands lipopolysaccharide and peptidoglycan, PCD monocytes produced more CXCL8 and IL-1β compared to controls. Moreover, PCD monocytes also responded stronger to IL-1β stimulation in terms of CXCL8 production. In conclusion, we revealed a potential link between CXCR2 and its ligand CXCL8 and the pathogenesis of PCD.

Clinical impact of Pseudomonas aeruginosa colonization in patients with Primary Ciliary Dyskinesia

BACKGROUND

Airway infections in Primary Ciliary Dyskinesia (PCD) are caused by different microorganisms, including pseudomonas aeruginosa (PA). The aim of this study was to investigate the association of PA colonization and the progression of lung disease in PCD.

METHODS

Data from 11PCD centers were retrospectively collected from 2008 to 2013. Patients were considered colonized if PA grew on at least two separate sputum cultures; otherwise, they were classified as non-colonized. These two groups were compared on the lung function computed tomography (CT) Brody score and other clinical parameters.

RESULTS

Data were available from 217 patients; 60 (27.6%) of whom were assigned to the colonized group. Patients colonized with PA were older and were diagnosed at a later age. Baseline forced expiratory volume at 1 s (FEV₁) was lower in the colonized group (72.4 ± 22.0 vs. 80.1 ± 18.9, % predicted, p = 0.015), but FEV₁ declined throughout the study period was similar in both groups. The colonized group had significantly worse CT-Brody scores (36.07 ± 24.38 vs. 25.56 ± 24.2, p = 0.034). A subgroup analysis with more stringent definitions of colonization revealed similar results.

CONCLUSIONS

Lung PA colonization in PCD is associated with more severe disease as shown by the FEV₁ and CT score. However, the magnitude of decline in pulmonary function was similar in colonized and non-colonized PCD patients.

The diagnosis of cystic fibrosis

Establishing the diagnosis of cystic fibrosis (CF) is straight forward in the majority of patients: they present with a clear clinical picture (most frequently chronic respiratory symptoms plus malabsorption), the sweat chloride value is>60mmol/L and two known disease causing CFTR mutations are identified. In less than 5% of subjects, mainly those with a milder or limited phenotype, the diagnostic process is more complex, because initial diagnostic test results are inconclusive: sweat chloride concentration in the intermediate range, less than 2 CF causing mutations identified or both. These patients should be referred to expert centers where bioassays of CFTR function like nasal potential difference measurement or intestinal current measurement can be done. Still, in some patients, despite symptoms compatible with CF and some indication of CFTR dysfunction (e.g. only intermediate sweat chloride value), diagnostic criteria are not met (e.g. only 1 CFTR mutation identified). For these subjects, the term CFTR related disorder (CFTR-RD) is used. Patients with disseminated bronchiectasis, congenital bilateral absence of the vas deferens and acute or recurrent pancreatitis may fall in this category. CF has a very wide disease spectrum and increasingly the diagnosis is being made during adult life, mainly in subjects with milder phenotypes. In many countries, nationwide CF newborn screening (NBS) has been introduced. In screen positive babies, the diagnosis of CF must be confirmed by a sweat test demonstrating a sweat chloride concentration above 60mmol/L. To achieve the benefit of NBS, every baby in whom the diagnosis of CF is confirmed must receive immediate follow-up and treatment in a CF reference center. CF NBS is not full proof: some diagnoses will be missed and in some babies the diagnosis cannot be confirmed nor ruled out with certainty. Screening algorithms that include gene sequencing will detect a high number of such babies that are screen positive with an inconclusive diagnosis (CFSPID). Even in 2016, the most reliable and widely available diagnostic test for CF is the measurement of chloride concentration in sweat. The method of choice is sweat induction by pilocarpine iontophoresis, followed by sweat collection on a gauze or filter paper or in a Macroduct coil. Since mutation specific therapies have become available, it is important to identify the mutations responsible for CF in each individual patient.

Cystic fibrosis carriership and tuberculosis: hints toward an evolutionary selective advantage based on data from the Brazilian territory

Background

The reason why Cystic Fibrosis (CF) is the most common fatal genetic disease among Caucasians has been incompletely studied. We aimed at deepening the hypothesis that CF carriers have a relative protection against Mycobacterium tuberculosis (Mtb) infection.

Methods

Applying spatial epidemiology, we studied the link between CF carriership rate and tuberculosis (TB) incidence in Brazil. We corrected for 5 potential environmental and 2 immunological confounders in this relation: monthly income, sanitary provisions, literacy rates, racial composition and population density along with AIDS incidence rates and diabetes mellitus type 2. Smoking data were incomplete and not available for analysis.

Results

A significant, negative correlation between CF carriership rate and TB incidence, independent of any of the seven confounders was found.

Conclusion

We provide exploratory support for the hypothesis that carrying a single CFTR mutation arms against Mtb infections.

Fifth Percentile Cutoff Values for Antipneumococcal Polysaccharide and Anti-Salmonella typhi Vi IgG Describe a Normal Polysaccharide Response

Background

Serotype-specific antibody responses to unconjugated pneumococcal polysaccharide vaccine (PPV) evaluated by a World Health Organization (WHO)-standardized enzyme-linked immunosorbent assay (ELISA) are the gold standard for diagnosis of specific polysaccharide antibody deficiency (SAD). The American Academy of Allergy, Asthma and Immunology (AAAAI) has proposed guidelines to interpret the PPV response measured by ELISA, but these are based on limited evidence. Additionally, ELISA is costly and labor-intensive. Measurement of antibody response to Salmonella typhi (S. typhi) Vi vaccine and serum allohemagglutinins (AHA) have been suggested as alternatives. However, there are no large cohort studies and cutoff values are lacking.

Objective

To establish cutoff values for antipneumococcal polysaccharide antibody response, anti-S. typhi Vi antibody, and AHA.

Methods

One hundred healthy subjects (10–55 years) were vaccinated with PPV and S. typhi Vi vaccine. Blood samples were obtained prior to and 3–4 weeks after vaccination. Polysaccharide responses to 3 serotypes were measured by WHO ELISA and to 12 serotypes by an in-house bead-based multiplex assay. Anti-S. typhi Vi IgG were measured with a commercial ELISA kit. AHA were measured by agglutination method.

Results

Applying AAAAI criteria, 30% of healthy subjects had a SAD. Using serotype-specific fifth percentile (p5) cutoff values for postvaccination IgG and fold increase pre- over postvaccination, only 4% of subjects had SAD. One-sided 95% prediction intervals for anti-S. typhi Vi postvaccination IgG (≥11.2 U/ml) and fold increase (≥2) were established. Eight percent had a response to S. typhi Vi vaccine below these cutoffs. AHA titer p5 cutoffs were ½ for anti-B and ¼ for anti-A.

Conclusion

We establish reference cutoff values for interpretation of PPV response measured by bead-based assay, cutoff values for S. typhi Vi vaccine responses, and normal values for AHA. For the first time, the intraindividual consistency of all three methods is studied in a large cohort.

Ethnicity impacts the cystic fibrosis diagnosis: A note of caution

BACKGROUND

The diagnosis of Cystic Fibrosis (CF) is by consensus based on the same parameters in all patients, yet the influence of ethnicity has only scarcely been studied. We aimed at elucidating the impact of Asian descent on the diagnosis of CF.

METHODS

We performed a retrospective analysis of the CFTR2 and UK CF databases for clinical phenotype, sweat chloride values and CFTR mutations and compared the diagnostic characteristics of Asian to non-Asian patients with CF.

RESULTS

Asian patients with CF do not have a worse clinical phenotype. The repeatedly reported lower FEV₁ of Asian patients with CF is attributable to the influence of ethnicity on lung function in general. However, pancreatic sufficiency is more common in Asian patients with CF. The diagnosis of CF in people with Asian ancestry is heterogeneous as mean sweat chloride values are lower (92±26 versus 99±22mmol/L in controls) and 14% have sweat chloride values below 60mmol/L (versus 6% in non-Asians). Also, CFTR mutations differ from those in Caucasians: 55% of British Asian patients with CF do not have one mutation included in the routine newborn screening panel.

CONCLUSIONS

Bringing together the largest cohort of patients with CF and Asian ethnicity, we demonstrate that Asian roots impact on all three CF diagnostic pillars. These findings have implications for clinical practice in the increasingly ethnically diverse Western population.

New horizons for cystic fibrosis treatment

Cystic fibrosis is an inherited multi-system disease associated with chronic lung infection, malabsorption, salt loss syndromes, male infertility and leading to numerous comorbidities. The landscape in cystic fibrosis care has changed markedly with currently more adult patients than children in many countries. Over 2000 different mutations in the CFTR gene have been reported and the majority are extremely rare. Understanding how CFTR mutations translate to disturbed synthesis or function of the CFTR protein has opened the way to 'personalized' treatments to correct the basic defect. The first 2 drugs have reached the clinic: a CFTR potentiator to augment CFTR channel function, and the combination of this potentiator with a corrector to increase CFTR expression at the cell membrane. To obtain robust correction of CFTR expression at the cell membrane, combinations of correctors with additive efficacy are under investigation. Other mutation type-specific treatments under clinical investigation are premature stop codon-read through drugs and antisense oligonucleotides that correct the basic defect at the mRNA level. Restoring the defective gene by gene editing can already be achieved ex vivo. Mutation agnostic treatments are explored as well: stabilizing CFTR expression at the cell membrane, circumventing the CFTR channel by blocking or activating other ion channels, and gene therapy. Combinations of these therapies can be anticipated. The pipeline of corrective strategies under clinical investigation is increasing continuously and a rising number of pharmaceutical companies are entering the field.

Beyond pancreatic insufficiency and liver disease in cystic fibrosis

Cystic fibrosis is a life shortening hereditary disease, primarily leading to progressive pulmonary infection and exocrine pancreatic dysfunction. Several gastrointestinal complications other than malabsorption can arise during the disease course and with the progressively increasing life span of patients with CF; new and more rare complications are being recognized. We review the literature on gastrointestinal manifestations in CF, excluding the liver and pancreas.

CONCLUSION

We describe the clinical presentation and treatment of more common conditions like gastroesophageal reflux, small intestinal bacterial overgrowth, intussusception, meconium ileus, distal intestinal obstruction syndrome, and constipation, and we also discuss what is known on celiac disease, appendicitis, fibrosing colonopathy, inflammation and inflammatory bowel disease and gastrointestinal cancer.

WHAT IS KNOWN

• Gastrointestinal complications arise early in the course of the disease and have a severe impact on the quality of life of the patients. What is New: • This review is a concise summary of the current literature on gastrointestinal complications of cystic fibrosis. • We focused on clinical presentation and diagnostic investigations and provide a comprehensive resume of the current treatment options.

rAAV-CFTRΔR Rescues the Cystic Fibrosis Phenotype in Human Intestinal Organoids and Cystic Fibrosis Mice

RATIONALE

Gene therapy holds promise for a curative mutation-independent treatment applicable to all patients with cystic fibrosis (CF). The various viral vector-based clinical trials conducted in the past have demonstrated safety and tolerance of different vectors, but none have led to a clear and persistent clinical benefit. Recent clinical breakthroughs in recombinant adeno-associated viral vector (rAAV)-based gene therapy encouraged us to reexplore an rAAV approach for CF.

OBJECTIVES

We evaluated the preclinical potential of rAAV gene therapy for CF to restore chloride and fluid secretion in two complementary models: intestinal organoids derived from subjects with CF and a CF mouse model, an important milestone toward the development of a clinical rAAV candidate for CF gene therapy.

METHODS

We engineered an rAAV vector containing a truncated CF transmembrane conductance regulator (CFTRΔR) combined with a short promoter (CMV173) to ensure optimal gene expression. A rescue in chloride and fluid secretion after rAAV-CFTRΔR treatment was assessed by forskolin-induced swelling in CF transmembrane conductance regulator (CFTR)-deficient organoids and by nasal potential differences in ΔF508 mice.

MEASUREMENTS AND MAIN RESULTS

rAAV-CFTRΔR transduction of human CFTR-deficient organoids resulted in forskolin-induced swelling, indicating a restoration of CFTR function. Nasal potential differences demonstrated a clear response to low chloride and forskolin perfusion in most rAAV-CFTRΔR-treated CF mice.

CONCLUSIONS

Our study provides robust evidence that rAAV-mediated gene transfer of a truncated CFTR functionally rescues the CF phenotype across the nasal mucosa of CF mice and in patient-derived organoids. These results underscore the clinical potential of rAAV-CFTRΔR in offering a cure for all patients with CF in the future.

Disease-specific clinical trials networks: the example of cystic fibrosis

This article describes the steps of the development and the structure of a disease-specific clinical trials network for cystic fibrosis in Europe. Activities such as reviewing study protocols, feasibility assessments, training and standardizing of procedures, and outcome measurements help to bring high-quality clinical trials to the patients. Cooperation with the pharmaceutical industry, other research networks, patient organizations, and regulatory agencies is very important throughout all activities.

CONCLUSION

The European Cystic Fibrosis Society-Clinical Trials Network facilitates the development of new treatments for a rare disease and could be a prototype for other diseases.

WHAT IS KNOWN

• Clinical research has led to the first approved treatments targeting the basic Cystic Fibrosis defect. • For a rare disease like Cystic Fibrosis, multicenter international collaboration is needed to obtain solid evidence when testing possible new treatments. What is New: • The Clinical Trials Network established by the European Cystic Fibrosis Society has grown to a fully operational network with well-defined structures, procedures and partnerships. • Standardization of outcome parameters, protocol review, feasibility assessment and other activities help to develop high quality, efficient, relevant and feasible clinical trials, with the aim to bring new treatments to the patients.

Searching for a cure for cystic fibrosis. A 25-year quest in a nutshell

After 25 years of intensive search, there is not yet a cure for cystic fibrosis (CF). However, the quest has led to major breakthroughs in understanding the basic disease defect and defining strategies to correct it. The first cystic fibrosis transmembrane conductance regulator (CFTR) modulators have been introduced in clinic. Some show an impressive clinical benefit, like the potentiator ivacaftor for the 4% of patients with a class III defect. Others offer at present only a limited benefit, like the combination corrector lumacaftor plus potentiator ivacaftor for subjects homozygous for F508del. These findings prove that the basic defect in CF can be modified and hold the promise that one day CF will no longer be a life-shortening disease.

CONCLUSION

This review updates the clinician on recent achievements as well as on the CF research pipeline.

WHAT IS KNOWN

Cystic fibrosis (CF) is a common and life-shortening disease that currently cannot be cured. However, for each of the six CF mutation classes, disease-modifying drugs are under way.

WHAT IS NEW

This review is a concise update for the clinician on new drugs that reached the CF clinical pipeline. The research strategies in CF have become a paradigm for clinical trials in other inherited diseases.

Treatment burden in patients with at least one class IV or V CFTR mutation

CFTR mutations are grouped according to disease-causing mechanism. Several studies demonstrated that patients having at least one mutation of class IV/V, present with a milder phenotype, but little is known about their relative treatment burden. We compared treatment burden between patients with two class I, II, or III mutations and patients with at least one mutation of class IV/V in the 2010 database of the Belgian CF Registry. We calculated a "Treatment Burden Index" (TBI) by assigning long term therapies to categories low, medium and high intensity, for differential weighing in the total score. There were 779 patients with two known class I/II/III mutations and 94 patients with at least one class IV/V mutation. Compared to class I/II/III, class IV/V patients had a lower median number of clinic visits (4 vs. 5; P < 0.001), a lower risk of hospitalization (24.7% vs. 50.8%; P < 0.001) and intravenous antibiotic treatment (23.5% vs. 46.0%; P < 0.001) and a lower median TBI (6 vs. 9; P < 0.001). These differences remained significant when only class IV/V patients with pancreatic insufficiency (n = 31) were considered. This study clearly demonstrates the significantly lower treatment burden in patients with CF and at least one class IV/V mutation compared to patients with two class I/II/III mutations and contributes to providing better individual counseling at time of diagnosis.

Lumacaftor-Ivacaftor in Patients with Cystic Fibrosis Homozygous for Phe508del CFTR

BACKGROUND

Cystic fibrosis is a life-limiting disease that is caused by defective or deficient cystic fibrosis transmembrane conductance regulator (CFTR) protein activity. Phe508del is the most common CFTR mutation.

METHODS

We conducted two phase 3, randomized, double-blind, placebo-controlled studies that were designed to assess the effects of lumacaftor (VX-809), a CFTR corrector, in combination with ivacaftor (VX-770), a CFTR potentiator, in patients 12 years of age or older who had cystic fibrosis and were homozygous for the Phe508del CFTR mutation. In both studies, patients were randomly assigned to receive either lumacaftor (600 mg once daily or 400 mg every 12 hours) in combination with ivacaftor (250 mg every 12 hours) or matched placebo for 24 weeks. The primary end point was the absolute change from baseline in the percentage of predicted forced expiratory volume in 1 second (FEV1) at week 24.

RESULTS

A total of 1108 patients underwent randomization and received study drug. The mean baseline FEV1 was 61% of the predicted value. In both studies, there were significant improvements in the primary end point in both lumacaftor-ivacaftor dose groups; the difference between active treatment and placebo with respect to the mean absolute improvement in the percentage of predicted FEV1 ranged from 2.6 to 4.0 percentage points (P<0.001), which corresponded to a mean relative treatment difference of 4.3 to 6.7% (P<0.001). Pooled analyses showed that the rate of pulmonary exacerbations was 30 to 39% lower in the lumacaftor-ivacaftor groups than in the placebo group; the rate of events leading to hospitalization or the use of intravenous antibiotics was lower in the lumacaftor-ivacaftor groups as well. The incidence of adverse events was generally similar in the lumacaftor-ivacaftor and placebo groups. The rate of discontinuation due to an adverse event was 4.2% among patients who received lumacaftor-ivacaftor versus 1.6% among those who received placebo.

CONCLUSIONS

These data show that lumacaftor in combination with ivacaftor provided a benefit for patients with cystic fibrosis homozygous for the Phe508del CFTR mutation. (Funded by Vertex Pharmaceuticals and others; TRAFFIC and TRANSPORT ClinicalTrials.gov numbers, NCT01807923 and NCT01807949.).

Proximity to blue spaces and risk of infection with Pseudomonas aeruginosa in cystic fibrosis: A case-control analysis

BACKGROUND

The acquisition of Pseudomonas aeruginosa in cystic fibrosis (CF) is associated with lower survival, decreased lung function, worse radiological scores, increased exacerbations and reduced nutritional status. Open water is a known reservoir and a potential source of exposure to P. aeruginosa.

METHODS

Twenty eight adult CF patients who had no history of P. aeruginosa and had negative P. aeruginosa IgG antibody levels, were matched by age and sex with 28 CF patients with chronic P. aeruginosa colonization. Straight line and closest walking distance from patient's residence to the nearest "blue space", i.e. surface water as determined by Google Earth, were compared between the two groups, and odds ratios (OR) were estimated using conditional logistic regression.

RESULTS

Patients who were never infected with P. aeruginosa lived significantly further away from a natural water source than P. aeruginosa colonized patients, both when considering shortest walking distance (mean 487 m vs 308 m, p=0.014) and beeline (mean 324 m vs 202 m, p=0.021). Conditional logistic regression (correcting for FEV1%) revealed ORs for chronic P. aeruginosa colonization of 0.35 (95% CI 0.13-0.98; p=0.045) and 0.12 (95% CI 0.02-0.81; p=0.028) for each doubling in the beeline or walking distance, respectively, between residence and open water.

CONCLUSION

We discovered that adult CF patients without P. aeruginosa infection live significantly further from blue space than CF patients with chronic P. aeruginosa colonization. Within the limitations of a case-control study, this may indicate that natural open water represents a source of infection by P. aeruginosa in CF.

REGISTRATION

The study was approved by the local ethical committee of the UZ Leuven, Belgium (ML-5028).

Lung structure-function correlation in patients with primary ciliary dyskinesia

BACKGROUND

Primary ciliary dyskinesia (PCD) is a rare disease, characterised by chronic airway infection. In cystic fibrosis, FEV1 is insensitive to detect patients with structural damage, and Lung Clearance Index (LCI) was proposed as a better marker of early lung damage. In PCD, the relationship between functional and structural abnormalities has been less studied. We aimed to re-examine this in a cohort of children and adults with mild to moderate PCD.

METHODS

Thirty-eight patients with PCD (5.2-25.0 years) and 70 healthy controls (4.4-25.8 years) were recruited to compare LCI, measured by N2 multiple breath washout and FEV1 in a prospective observational trial. In a subset of 30 patients who underwent chest imaging, structural abnormalities were evaluated with cystic fibrosis computed tomography (CFCT) scores.

RESULTS

LCI was abnormal in 28 of 38 patients and a moderate correlation was observed between LCI and FEV1 (r=-0.519, p=0.001). Moreover, LCI correlated well with CFCT total score (r=0.800, p<0.001) and also with subscores for airway wall thickening (r=0.809, p<0.001), mucus plugging (r=0.720, p<0.001) and bronchiectasis (r=0.494, p<0.001). Concordance was seen between LCI and CFCT in 25 of 30 (83%) patients, but between FEV1 and CFCT in only 16 of 30 (53%) patients. LCI was more sensitive (90.9%, 95% CI 70.8 to 98.6) to detect patients with structural abnormalities than FEV1 (36.4%, 95% CI 17.2 to 59.3).

CONCLUSIONS

We demonstrated that measuring LCI in patients with PCD is of clinical relevance; it was more frequently abnormal than FEV1, correlated well with CFCT and was more sensitive than FEV1 to detect patients with structural abnormalities.