Emerging drugs for bronchiectasis: an update

Pharmacotherapeutic strategies for treating bronchiectasis in pediatric patients

INTRODUCTION

The social and medical costs of bronchiectasis in children are becoming considerable due to its increasing prevalence. Early identification and intensive treatment of bronchiectasis are needed to decrease the morbidity and mortality associated with bronchiectasis in children.

AREAS COVERED

This review presents the current pharmacotherapeutic strategies for treating bronchiectasis in children with a focus on non-cystic fibrosis bronchiectasis.

EXPERT OPINION

Evidence for the effectiveness of diverse treatment strategies in bronchiectasis is lacking, particularly in children, although the disease burden is substantial for bronchiectasis. Most treatment strategies for non-cystic fibrosis bronchiectasis in children have been extrapolated from those in adults with bronchiectasis or children with cystic fibrosis. Antibiotics combined with an active airway clearance therapy via the inhalation of mucoactive agents can stabilize bronchiectasis. The timely and intensive administration of antibiotics during acute exacerbation of bronchiectasis is essential to prevent its progression in children. To suppress the bacterial loads in the airway, systemic or inhaled antibiotics can be administered intermittently or continuously. However, studies on these protocols, including the appropriate duration and effective dosages are lacking. Long-term administration of azithromycin for 12-24 months may reduce the exacerbation frequency with the increased carriage rate of azithromycin-resistant bacteria.

Bronchiectasis in children: diagnosis and treatment

Bronchiectasis is conventionally defined as irreversible dilatation of the bronchial tree. Bronchiectasis unrelated to cystic fibrosis is an increasingly appreciated cause of chronic respiratory-related morbidity worldwide. Few randomised controlled trials provide high-level evidence for management strategies to treat the children affected by bronchiectasis. However, both decades-old and more recent studies using technological advances support the notion that prompt diagnosis and optimal management of paediatric bronchiectasis is particularly important in early childhood. Although considered to be of a non-reversible nature, mild bronchiectasis determined by radiography might be reversible at any age if treated early, and the lung function decline associated with disease progression could then be halted. Although some management strategies are extrapolated from cystic fibrosis or adult-based studies, or both, non-cystic fibrosis paediatric-specific data to help diagnose and manage these children still need to be generated. We present current knowledge and an updated definition of bronchiectasis, and review controversies relating to the management of children with bronchiectasis, including applying the concept of so-called treatable traits.

An update on pediatric bronchiectasis

INTRODUCTION

The prevalence and awareness of bronchiectasis not related to cystic fibrosis (CF) is increasing and it is now recognized as a major cause of respiratory morbidity, mortality and healthcare utilization worldwide. The need to elucidate the early origins of bronchiectasis is increasingly appreciated and has been identified as an important research priority. Current treatments for pediatric bronchiectasis are limited to antimicrobials, airway clearance techniques and vaccination. Several new drugs targeting airway inflammation are currently in development. Areas covered: Current management of pediatric bronchiectasis, including discussion on therapeutics, non-pharmacological interventions and preventative and surveillance strategies are covered in this review. We describe selected adult and pediatric data on bronchiectasis treatments and briefly discuss emerging therapeutics in the field. Expert commentary: Despite the burden of disease, the number of studies evaluating potential treatments for bronchiectasis in children is extremely low and substantially disproportionate to that for CF. Research into the interactions between early life respiratory tract infections and the developing immune system in children is likely to reveal risk factors for bronchiectasis development and inform future preventative and therapeutic strategies. Tailoring interventions to childhood bronchiectasis is imperative to halt the disease in its origins and improve adult outcomes.

Pediatric bronchiectasis: No longer an orphan disease

Bronchiectasis is described classically as a chronic pulmonary disorder characterized by a persistent productive cough and irreversible dilatation of one or more bronchi. However, in children unable to expectorate, cough may instead be wet and intermittent and bronchial dilatation reversible in the early stages. Although still considered an orphan disease, it is being recognized increasingly as causing significant morbidity and mortality in children and adults in both affluent and developing countries. While bronchiectasis has multiple etiologies, the final common pathway involves a complex interplay between the host, respiratory pathogens and environmental factors. These interactions lead to a vicious cycle of repeated infections, airway inflammation and tissue remodelling resulting in impaired airway clearance, destruction of structural elements within the bronchial wall causing them to become dilated and small airway obstruction. In this review, the current knowledge of the epidemiology, pathobiology, clinical features, and management of bronchiectasis in children are summarized. Recent evidence has emerged to improve our understanding of this heterogeneous disease including the role of viruses, and how antibiotics, novel drugs, antiviral agents, and vaccines might be used. Importantly, the management is no longer dependent upon extrapolating from the cystic fibrosis experience. Nevertheless, substantial information gaps remain in determining the underlying disease mechanisms that initiate and sustain the pathophysiological pathways leading to bronchiectasis. National and international collaborations, standardizing definitions of clinical and research end points, and exploring novel primary prevention strategies are needed if further progress is to be made in understanding, treating and even preventing this often life-limiting disease.

Bronchiectasis: Current Concepts in Pathogenesis, Immunology, and Microbiology

Bronchiectasis is a disorder of persistent lung inflammation and recurrent infection, defined by a common pathological end point: irreversible bronchial dilatation arrived at through diverse etiologies. This suggests an interplay between immunogenetic susceptibility, immune dysregulation, bacterial infection, and lung damage. The damaged epithelium impairs mucus removal and facilitates bacterial infection with increased cough, sputum production, and airflow obstruction. Lung infection is caused by respiratory bacterial and fungal pathogens, including Pseudomonas aeruginosa, Haemophilus, Aspergillus fumigatus, and nontuberculous mycobacteria. Recent studies have highlighted the relationship between the lung microbiota and microbial-pathogen niches. Disease may result from environments favoring interleukin-17-driven neutrophilia. Bronchiectasis may present in autoimmune disease, as well as conditions of immune dysregulation, such as combined variable immune deficiency, transporter associated with antigen processing-deficiency syndrome, and hyperimmunoglobulin E syndrome. Differences in prevalence across geography and ethnicity implicate an etiological mix of genetics and environment underpinning susceptibility.