GSK presents asthma data that shows no additional clinical efficacy benefits for ICS-treatments with a small particle size

GSK today presented data at the British Thoracic Society (BTS) meeting from a systematic analysis of 25 randomised control studies (RCTs), including a meta-analysis of three key efficacy outcomes,  which explored the potential impact of the particle size of different ICS-containing asthma medicines, including Seretide/Advair (salmeterol/fluticasone proprionate) on patient outcomes.

Previous studies have shown that the optimal particle size for an inhaled respiratory medicine is between 1-5 microns.  However it has been suggested for both asthma and COPD that inhaled corticosteroid (ICS) containing medicines with ‘smaller’ particles (<2 microns) may deliver a more uniform distribution of the ICS within the airways, particularly in the small airways, which could translate to more favourable patient outcomes.  No large-scale RCTs or analyses have been conducted to-date to investigate if particle size influences asthma or COPD patient outcomes.  As a result, an extensive scientific literature review and systematic analysis was conducted to explore this hypothesis further in asthma.

This review examined the efficacy and safety outcomes from asthma studies of medicines containing fluticasone propionate (FP), which has a ‘standard’ particle size, and alternative smaller particle ICS containing medicines, HFA beclomethasone dipropionate (BDP) and ciclesonide (CIC). Adolescents/adults and paediatric data were analysed separately. 

The results showed that medicines with a small particle size did not confer additional clinical efficacy or additional safety benefits in asthma patients compared to those with a ‘standard’ particle size.

Neil Barnes, Global Franchise Medical Head, Respiratory, GSK said: “Inhaled corticosteroids are the backbone of treatment for patients with persistent asthma, so the more we understand about these medicines and their relative benefits, the greater our ability to improve patient outcomes.

“These data support the positive impact that treatment with the available ICS-treatments can have, but importantly what they also show is that although individual molecules have different characteristics, a small particle size does not offer any additional benefit for the majority of patients and should not drive treatment choice.  As clinicians it is important when making treatment decisions for our patients that we focus on the efficacy and safety offered by an individual medicine, not the relative particle size, which this analysis has shown confers no additional benefit.”

Analysis Results

For the meta-analysis in adult/adolescents, treatment comparisons were made using absolute treatment differences between FP and small particle ICS medicines.  The findings were as follows:

• No clinically meaningful differences were observed for a number of efficacy endpoints: Change in forced expiratory volume in 1 second (FEV1), morning peak flow and rescue medication use.
• There was a statistically significant difference favouring FP on % predicted forced expiratory flow between 25% and 75% of forced vital capacity (FEF25-75%), a known indicator of small airways function, but this was not clinically significant
• Due to the disparity of endpoints and measures used in these studies, it was not possible to include any safety data in the meta-analysis.  However patients receiving FP experienced more local ICS effects than those receiving ciclesonide.

These findings show that whilst there is a known variation in the particle size of the different ICS molecules available to treat patients with asthma, this aspect of an inhaled medicine has little impact on clinical outcomes.