Hypertonic saline in patients with primary ciliary dyskinesia: on the road to evidence-based treatment for a rare lung disease

A BEAT-PCD consensus statement: a core outcome set for pulmonary disease interventions in primary ciliary dyskinesia

Background

Consistent use of reliable and clinically appropriate outcome measures is a priority for clinical trials, with clear definitions to allow comparability. We aimed to develop a core outcome set (COS) for pulmonary disease interventions in primary ciliary dyskinesia (PCD).

Methods

A multidisciplinary international PCD expert panel was set up. A list of outcomes was created based on published literature. Using a modified three-round e-Delphi technique, the panel was asked to decide on relevant end-points related to pulmonary disease interventions and how they should be reported. First, inclusion of an outcome in the COS was determined. Second, the minimum information that should be reported per outcome. The third round finalised statements. Consensus was defined as ≥80% agreement among experts.

Results

During the first round, experts reached consensus on four out of 24 outcomes to be included in the COS. Five additional outcomes were discussed in subsequent rounds for their use in different subsettings. Consensus on standardised methods of reporting for the COS was reached. Spirometry, health-related quality-of-life scores, microbiology and exacerbations were included in the final COS.

Conclusion

This expert consensus resulted in a COS for clinical trials on pulmonary health among people with PCD.

Lower airway clinical outcome measures for use in primary ciliary dyskinesia research: a scoping review

Objectives

Disease-specific, well-defined and validated clinical outcome measures are essential in designing research studies. Poorly defined outcome measures hamper pooling of data and comparisons between studies. We aimed to identify and describe pulmonary outcome measures that could be used for follow-up of patients with primary ciliary dyskinesia (PCD).

Methods

We conducted a scoping review by systematically searching MEDLINE, Embase and the Cochrane Database of Systematic Reviews online databases for studies published from 1996 to 2020 that included ≥10 PCD adult and/or paediatric patients.

Results

We included 102 studies (7289 patients). 83 studies reported on spirometry, 11 on body plethysmography, 15 on multiple-breath washout, 36 on high-resolution computed tomography (HRCT), 57 on microbiology and 17 on health-related quality of life. Measurement and reporting of outcomes varied considerably between studies (e.g. different scoring systems for chest HRCT scans). Additionally, definitions of outcome measures varied (e.g. definition of chronic colonisation by respiratory pathogen), impeding direct comparisons of results.

Conclusions

This review highlights the need for standardisation of measurements and reporting of outcome measures to enable comparisons between studies. Defining a core set of clinical outcome measures is necessary to ensure reproducibility of results and for use in future trials and prospective cohorts.

Bronchodilator response to albuterol nebulized with hypertonic saline in asthmatic children

INTRODUCTION

Asthma is distinguished by bronchial obstruction reversible by bronchodilators. The first-line treatment for asthmatic exacerbations is the use of inhaled beta-agonists, by pressurized metered-dose inhalers or nebulized with normal saline solution (NSS). There are no reports of nebulized beta agonists' efficacy in asthmatic children when administered with hypertonic saline solution (HSS).

OBJECTIVE

To evaluate bronchodilator responses (BDR) to albuterol nebulized with 3%-HSS in asthmatic children, compared to albuterol nebulized with NSS.

POPULATION AND METHODS

In a prospective, experimental, double-blind, randomized clinical study, children with a confirmed diagnosis of asthma with mild or moderate bronchial obstruction (FEV₁ 40%-79% of predicted) were randomized to receive a nebulization with 2.5 mg of albuterol diluted in 3 cc of 3%-HSS or NSS (0.9%), by means of a jet nebulizer. After 30 min, the BDR was assessed.

RESULTS

Fifty patients (mean age 12.0 ± 3 years, 29 males) were enrolled; 25 were randomized to the 3%-HSS group (FEV₁ 65.2% ± 10) and 25 to the NSS group (FEV₁ 69.1% ± 7.1). The BDR of FEV₁ was 41.2% (SD: ±20.1; 95% confidence interval [CI]: 35.1-50.4) and 17.3% (SD: ±19.4; 95% CI: 9.7-24.9) (p < .0001) and of maximum mid-expiratory flow was 130% (SD: ±90.8; 95% CI: 94.6-166) and 69.8% (SD: ±72.5; 95% CI: 41.4-98.2) (p < .01), for the 3%-HSS and NSS groups, respectively.

CONCLUSION

Albuterol produces a greater BDR when nebulized with 3%-HSS compared to NSS in asthmatic children with mild or moderate bronchial obstruction.

Current and Future Treatments in Primary Ciliary Dyskinesia

Primary ciliary dyskinesia (PCD) is a rare genetic ciliopathy in which mucociliary clearance is disturbed by the abnormal motion of cilia or there is a severe reduction in the generation of multiple motile cilia. Lung damage ensues due to recurrent airway infections, sometimes even resulting in respiratory failure. So far, no causative treatment is available and treatment efforts are primarily aimed at improving mucociliary clearance and early treatment of bacterial airway infections. Treatment guidelines are largely based on cystic fibrosis (CF) guidelines, as few studies have been performed on PCD. In this review, we give a detailed overview of the clinical studies performed investigating PCD to date, including three trials and several case reports. In addition, we explore precision medicine approaches in PCD, including gene therapy, mRNA transcript and read-through therapy.

[Management of Primary Ciliary Dyskinesia]

Die Primäre Ciliäre Dyskinesie (PCD, MIM 242650) ist eine seltene hereditäre Multisystemerkrankung mit klinisch heterogenem Phänotyp. Leitsymptom ist eine chronische Sekretretention der oberen und unteren Atemwege, welche durch die Dysfunktion motiler respiratorischer Zilien entsteht. In der Folge kommt es zur Ausbildung von Bronchiektasen, häufig zu einer Infektion durch Pseudomonas aeruginosa sowie einer abnehmenden Lungenfunktion bis hin zum Lungenversagen.

Bislang gibt es kaum evidenzbasierte Therapieempfehlungen, da randomisierte Langzeitstudien zur Behandlung der PCD fehlten. In diesem Jahr wurden die Daten einer ersten placebokontrollierten Medikamentenstudie bei PCD veröffentlicht. Anlässlich dieses Meilensteins im Management der PCD wurde der vorliegende Übersichtsartikel als Konsens von Patientenvertretern sowie Klinikern, die langjährige Erfahrung in der Behandlung der PCD haben, verfasst. Diese Arbeit bietet eine Zusammenfassung aktuell eingesetzter Behandlungsverfahren, die überwiegend auf persönlichen Erfahrungen und Expertenmeinungen beruhen oder von anderen Atemwegserkrankungen wie der Cystischen Fibrose (CF), COPD oder Bronchiektasen-Erkrankung abgeleitet werden. Da es derzeit keine kurative Therapie für PCD gibt, stehen symptomatische Maßnahmen wie die regelmäßige Reinigung der Atemwege und die Behandlung von rezidivierenden Atemwegsinfektionen im Fokus. Nicht respiratorische Manifestationen werden organspezifisch behandelt. Um neben der ersten Medikamentenstudie mehr evidenzbasiertes Wissen zu generieren, werden weitere Projekte etabliert, u. a. ein internationales PCD-Register. Hierüber wird Patienten der Zugang zu klinischen und wissenschaftlichen Studien erleichtert und die Vernetzung behandelnder Zentren gefördert. Des Weiteren können Erkenntnisse über eine Genotyp-spezifische Erkrankungsschwere erlangt werden, um folglich die therapeutische Versorgung der Patienten zu verbessern und somit zu individualisieren.

Primary ciliary dyskinesia: a major player in a bigger game

Primary ciliary dyskinesia (PCD) is an inherited disorder of clinical and genetic heterogeneity resulting from mutations in genes involved in the transport, assembly and function of motile cilia. The resulting impairment in mucociliary clearance means patients suffer from chronic progressive lung disease, bronchiectasis, rhinosinusitis and middle ear disease. Subfertility is common to both male and female patients. Situs abnormalities occur in around half of patients, with a subgroup suffering more complex situs arrangements where congenital heart defects or other organ abnormalities frequently coexist. Variations from the classical PCD phenotype are increasingly recognised where overlapping features across a range of motile and nonmotile ciliopathies are redefining our approach to both diagnosis and management of these complex conditions. PCD offers an ideal opportunity for direct visualisation of ciliary function and structure, following nasal brush biopsy, allowing opportunities for researchers to directly interrogate the downstream impact of loss of function mutations. In turn, this has led to rapid advances in the development of new diagnostic tests. These advances mean that PCD is an excellent disease model for understanding the genetic and mechanistic causes of the clinical phenotype for all respiratory ciliopathies. Furthermore, the overlapping role of motile ciliary defects in a wider set of complex and syndromic disorders related to loss of function mutations in primary, nonmotile cilia has been recognised. As we better understand the role of ciliary defects in a broad spectrum of diseases, we should aim to map out a framework through which we can identify, diagnose and treat all respiratory ciliopathies.

Key points

Primary ciliary dyskinesia is just one of a group of conditions where a heterogeneous array of genetic mutations affect the assembly or structure of motile cilia.Overlapping phenotypes between motile and nonmotile ciliopathies are redefining the diagnostic and therapeutic approach to encompass all ciliopathy patients with a respiratory phenotype.An extended diagnostic algorithm may be required to capture the majority of cases with a respiratory ciliopathy, including patients with syndromic ciliopathies.The terminology around disorders of motile cilia is becoming more descriptive to better reflect the heterogeneity and underlying disease mechanisms across the spectrum of respiratory ciliopathies.

Educational aims

To summarise the existing knowledge base around the disease mechanisms for respiratory ciliopathies, including primary ciliary dyskinesia (PCD).To explore and understand the reasons for changing terminology around respiratory ciliopathies.To emphasise key messages around the diagnosis and treatment of all ciliopathies.Diagnosing PCD is complex and time consuming, and there is no single stand-alone test that can confirm or exclude a diagnosis in all cases.

Access to medicines for rare diseases: beating the drum for primary ciliary dyskinesia

Rare diseases are collectively common, affecting an estimated 6.2% of the world's population [1], but each rare disease affects fewer than 4 to 5 in 10 000 individuals in Europe or less than 200 000 individuals in the USA [2]. Patients with rare diseases are often disadvantaged by late diagnosis and off-label prescribing of medicines [3]. Primary ciliary dyskinesia (PCD) is a genetic disease of impaired motile ciliary function that does not have a unique International Classification of Diseases (ICD)-10 code or licensed treatments, although Q34.8 denoting “other specified malformations of the respiratory tract” including nasopharyngeal atresia has also been applicable to PCD since 2017. The disease is characterised by mucus stagnation leading to chronic airway infection, bronchiectasis, chronic rhinosinusitis, reduced fertility and abnormalities of organ laterality with an associated increased risk of complex congenital heart disease [4]. The estimated prevalence of PCD in Europe is around 1 in 10 000 to 1 in 20 000 [5]. The international PCD cohort (iPCD) includes over 3800 PCD patients ranging in age from under 12 months to over 80 years, from Europe, Northern and Southern America, Australia and Western Asia [6]. Under-diagnosis of PCD is due to a lack of awareness among the general public and physicians in general, as well as a lack of diagnostic expertise in some countries [7]. Tools to help physicians identify patients needing testing (e.g. PICADAR) [8] and the European Respiratory Society (ERS) guidelines for diagnostic testing [9] aim to improve this. In contrast to cystic fibrosis (CF), a monogenic disease, PCD is caused by mutations in one of at least 45 identified genes for which there is no effective mutation-specific therapy; this is likely to be a long way off for most patients [10]. Thus, treatment aims to prevent and manage disease complications. Even then, the lack of an evidence base for supportive treatment in PCD means that treatment recommendations are based on expert opinion and extrapolated from CF despite differing pathophysiology [11].

Primary ciliary dyskinesia, a rare disease causing bronchiectasis, lacks a sound evidence base for treatment. @beatpcd proposes 1) forming a PCD European clinical trial network to address this situation and 2) conducting n-of-1 trials to access medication.https://bit.ly/3j5blfM

Motile ciliopathies

Motile cilia are highly complex hair-like organelles of epithelial cells lining the surface of various organ systems. Genetic mutations (usually with autosomal recessive inheritance) that impair ciliary beating cause a variety of motile ciliopathies, a heterogeneous group of rare disorders. The pathogenetic mechanisms, clinical symptoms and severity of the disease depend on the specific affected genes and the tissues in which they are expressed. Defects in the ependymal cilia can result in hydrocephalus, defects in the cilia in the fallopian tubes or in sperm flagella can cause female and male subfertility, respectively, and malfunctional motile monocilia of the left-right organizer during early embryonic development can lead to laterality defects such as situs inversus and heterotaxy. If mucociliary clearance in the respiratory epithelium is severely impaired, the disorder is referred to as primary ciliary dyskinesia, the most common motile ciliopathy. No single test can confirm a diagnosis of motile ciliopathy, which is based on a combination of tests including nasal nitric oxide measurement, transmission electron microscopy, immunofluorescence and genetic analyses, and high-speed video microscopy. With the exception of azithromycin, there is no evidence-based treatment for primary ciliary dyskinesia; therapies aim at relieving symptoms and reducing the effects of reduced ciliary motility.

Clinical features and management of children with primary ciliary dyskinesia in England

OBJECTIVE

In England, the National Health Service commissioned a National Management Service for children with primary ciliary dyskinesia (PCD). The aims of this study were to describe the health of children seen in this Service and compare lung function to children with cystic fibrosis (CF).

DESIGN

Multi-centre service evaluation of the English National Management PCD Service.

SETTING

Four nationally commissioned PCD centres in England.

PATIENTS

333 children with PCD reviewed in the Service in 2015; lung function data were also compared with 2970 children with CF.

RESULTS

Median age at diagnosis for PCD was 2.6 years, significantly lower in children with situs inversus (1.0 vs 6.0 years, p<0.001). Compared with national data from the CF Registry, mean (SD) %predicted forced expiratory volume in one second (FEV₁) was 76.8% in PCD (n=240) and 85.0% in CF, and FEV₁ was lower in children with PCD up to the age of 15 years. Approximately half of children had some hearing impairment, with 26% requiring hearing aids. Children with a lower body mass index (BMI) had lower FEV₁ (p<0.001). One-third of children had positive respiratory cultures at review, 54% of these grew Haemophilus influenzae.

CONCLUSIONS

We provide evidence that children with PCD in England have worse lung function than those with CF. Nutritional status should be considered in PCD management, as those with a lower BMI have significantly lower FEV₁. Hearing impairment is common but seems to improve with age. Well-designed and powered randomised controlled trials on management of PCD are needed to inform best clinical practice.

Proceedings of the 4th BEAT-PCD Conference and 5th PCD Training School

Primary ciliary dyskinesia (PCD) is an inherited ciliopathy leading to chronic suppurative lung disease, chronic rhinosinusitis, middle ear disease, sub-fertility and situs abnormalities. As PCD is rare, it is important that scientists and clinicians foster international collaborations to share expertise in order to provide the best possible diagnostic and management strategies. 'Better Experimental Approaches to Treat Primary Ciliary Dyskinesia' (BEAT-PCD) is a multidisciplinary network funded by EU COST Action (BM1407) to coordinate innovative basic science and clinical research from across the world to drive advances in the field. The fourth and final BEAT-PCD Conference and fifth PCD Training School were held jointly in March 2019 in Poznan, Poland. The varied program of plenaries, workshops, break-out sessions, oral and poster presentations were aimed to enhance the knowledge and skills of delegates, whilst also providing a collaborative platform to exchange ideas. In this final BEAT-PCD conference we were able to build upon programmes developed throughout the lifetime of the COST Action. These proceedings report on the conference, highlighting some of the successes of the BEAT-PCD programme.

Nebulized hypertonic saline in noncystic fibrosis bronchiectasis: a comprehensive review

Bronchiectasis occurs as a result of a vicious circle consisting of an impaired mucociliary transport system, inflammation, and infection and repair of the airways. Damage to the mucociliary system prevents secretion elimination and facilitates bacterial growth and bronchial inflammation. To facilitate mucociliary clearance, current guidelines recommend the use of hypertonic saline (HS) solutions in patients with bronchiectasis not secondary to cystic fibrosis (CF), although the evidence of efficacy in this pathology is sparse. A high percentage of patients with CF and bronchiectasis tolerate HS solutions, but often patients report cough, dyspnoea, throat irritation, or salty taste after inhalation. These adverse effects negatively impact adherence to treatment, which sometimes must be discontinued. Some studies have shown that the addition of hyaluronic acid increases the tolerability of HS solutions, both in patients with CF and in bronchiectasis of other etiologies. We aimed to review the benefits and safety of HS solutions in patients with bronchiectasis. The reviews of this paper are available via the supplemental material section.

Bronchiectasis

Bronchiectasis refers to abnormal dilatation of the bronchi. Airway dilatation can lead to failure of mucus clearance and increased risk of infection. Pathophysiological mechanisms of bronchiectasis include persistent bacterial infections, dysregulated immune responses, impaired mucociliary clearance and airway obstruction. These mechanisms can interact and self-perpetuate, leading over time to impaired lung function. Patients commonly present with productive cough and recurrent chest infections, and the diagnosis of bronchiectasis is based on clinical symptoms and radiological findings. Bronchiectasis can be the result of several different underlying disorders, and identifying the aetiology is crucial to guide management. Treatment is directed at reducing the frequency of exacerbations, improving quality of life and preventing disease progression. Although no therapy is licensed for bronchiectasis by regulatory agencies, evidence supports the effectiveness of airway clearance techniques, antibiotics and mucolytic agents, such as inhaled isotonic or hypertonic saline, in some patients. Bronchiectasis is a disabling disease with an increasing prevalence and can affect individuals of any age. A major challenge is the application of emerging phenotyping and endotyping techniques to identify the patient populations who would most benefit from a specific treatment, with the goal of better targeting existing and emerging treatments and achieving better outcomes.

Proceedings of the 2nd BEAT-PCD conference and 3rd PCD training school: part 1

Primary ciliary dyskinesia (PCD) is a rare heterogenous condition that causes progressive suppurative lung disease, chronic rhinosinusitis, chronic otitis media, infertility and abnormal situs. 'Better Experimental Approaches to Treat Primary Ciliary Dyskinesia' (BEAT-PCD) is a network of scientists and clinicians coordinating research from basic science through to clinical care with the intention of developing treatments and diagnostics that lead to improved long-term outcomes for patients. BEAT-PCD activities are supported by EU funded COST Action (BM1407). The second BEAT-PCD conference, and third PCD training school were held jointly in April 2017 in Valencia, Spain. Presentations and workshops focussed on advancing the knowledge and skills relating to PCD in: basic science, epidemiology, diagnostic testing, clinical management and clinical trials. The multidisciplinary conference provided an interactive platform for exchanging ideas through a program of lectures, poster presentations, breakout sessions and workshops. Three working groups met to plan consensus statements. Progress with BEAT-PCD projects was shared and new collaborations were fostered. In this report, we summarize the meeting, highlighting developments made during the meeting.

Clinical care for primary ciliary dyskinesia: current challenges and future directions

Primary ciliary dyskinesia (PCD) is a rare genetic disease that affects the motility of cilia, leading to impaired mucociliary clearance. It is estimated that the vast majority of patients with PCD have not been diagnosed as such, providing a major obstacle to delivering appropriate care. Challenges in diagnosing PCD include lack of disease-specific symptoms and absence of a single, “gold standard”, diagnostic test. Management of patients is currently not based on high-level evidence because research findings are mostly derived from small observational studies with limited follow-up period. In this review, we provide a critical overview of the available literature on clinical care for PCD patients, including recent advances. We identify barriers to PCD research and make suggestions for overcoming challenges.

Challenges in PCD must be overcome through international collaboration; networks must build on recent advanceshttp://ow.ly/4d4I30dXzWg