Microbiome Use to Stratify Use of Inhaled Corticosteroids: MUSIC Trial

Inhaled corticosteroids (ICS) are commonly prescribed for patients with chronic obstructive pulmonary disease (COPD), but their role in the management of COPD is currently being re-evaluated in light of new evidence and the emergence of alternative treatments. Studies have shown that the use of ICS and particularly ICS combined with long acting beta2-adrenoceptor agonists (LABA) in individuals with COPD reduces the frequency of COPD exacerbations and improves health status and lung function compared to LABA alone or placebo. The current National Institute for Care Excellence (NICE) guidelines for COPD recommend ICS for patients with a forced expiratory volume in 1 second below 50% predicted, or for patients with higher lung function who have persisting symptoms or exacerbations despite treatment with long acting bronchodilators. Data suggests that up to 75% of patients with COPD in the United Kingdom (UK) are subsequently prescribed ICS.

The daily dose of ICS utilised in COPD treatments are much higher than those used in asthma treatments, with licensed daily doses being 1000 mcg fluticasone propionate (2000 mcg beclomethasone dipropionate (BDP) equivalents) or 800 mcg budesonide (800 mcg BDP equivalents).

Recent concerns have been expressed about the safety of ICS in COPD following several randomised controlled trials of fluticasone propionate and fluticasone furoate, among others, demonstrating an increase in rates of pneumonia as an adverse event. Several systematic reviews and observational studies confirm an association between ICS use and risk of pneumonia.

All ICS preparations have been associated with an increased risk of pneumonia in either randomised trials or observational studies leading to warnings from national regulatory authorities and leading experts.

It is likely however, that the risk of pneumonia is not equal across all ICS doses and molecules. Research into this area is greatly limited by the lack of head to head comparisons between different ICS preparations in COPD.

It is hypothesised that the anti-inflammatory and immunosuppressive effects of ICS lead to increase susceptibility to colonisation of the upper respiratory tract with pathogenic bacteria associated with pneumonia such as S. pneumoniae and Haemophilus influenzae. This study will establish one potential mechanism for the increased susceptibility to pneumonia in ICS users and assess intraclass differences in ICS molecules used in COPD and the effect of ICS dose. It is known that changes in the microbiome in COPD are associated with disease severity and with lung inflammation. Demonstrating that different COPD treatments can have different effects on the lung microbiome is an important step in understanding clinical differences in the safety and effectiveness of different treatments for severe COPD. The longer term clinical objective of this study is therefore to determine whether a proportion of patients with COPD might be more safely managed with either lower dose, pharmacologically different ICS preparations or with LABA/LAMA therapies to reduce the risk of pneumonia.

Hypothesis Fluticasone propionate will facilitate a higher level of bacterial airway colonisation by pathogens associated with pneumonia compared to budesonide or treatment exclusively with bronchodilators, therefore providing a mechanistic explanation for increased pneumonia risk associated with ICS.

STUDY OBJECTIVES To determine a potential mechanism of inhaled corticosteroid associated pneumonia in COPD by demonstrating ICS effects on the upper (throat and nasal swabs) and lower airway (sputum) microbiome.

To determine the mechanism of observed differences in pneumonia risk between fluticasone propionate, and budesonide by demonstrating differential effects on the airway microbiome.