Randomised controlled trials of therapies in severe asthma are poorly generalisable, study says

17 December, 2018

A new study published in the European Respiratory Journal has found that randomised controlled trials (RCTs) of biological therapies in severe asthma are poorly generalisable, with most patients excluded by outdated disease concepts, despite possessing the targetable trait addressed by the treatment.

Researchers aimed to establish how the disparity between research trial populations and those in clinical practice relates to RCTs of phenotype-targeted biological therapies in severe asthma.

Using detailed characterisation data for 342 severe asthma patients within the Wessex Severe Asthma Cohort (WSAC), researchers compared trial eligibility criteria for published phase IIB and phase III RCTs which evaluated biological therapies in severe asthma since 2000. In total, 37 RCTs evaluating 20 biological therapies were identified.

Analysis showed that just 9.8% of severe asthma patients were found to be eligible for enrolment in the phase III trials. Conditions for airflow obstruction, bronchodilator reversibility and smoking history would have excluded significant numbers of patients.

Further, only 21.1% of patients with severe eosinophilic asthma were found to be eligible for enrolment in the phase III licensing trials of interleukin (IL)-5/5R targeted therapies.

The researchers say that despite including only well characterised and optimally treated severe asthmatics under specialist care within the WSAC study, the vast majority of patients were excluded from trial participation by criteria designed to re-confirm diagnostic labels, rather than by biomarker criteria that predict the characteristic addressed by the treatment.