AstraZeneca has called time on a mid-stage trial assessing an experimental inhaled interferon beta licensed from Southampton, UK-based group Synairgen.

The drugs giant said it has decided to stop a Phase IIa study assessing the antiviral AZD9412 in patients with asthma, "based on an interim analysis, where an overall very low number of reported severe exacerbations could make primary endpoint conclusions difficult".

In the INEXAS trial, asthma patients were dosed with placebo or AZD9412 at the onset of common cold symptoms, after previous research indicate that boosting the antiviral defences of the lung with AZD9412 during this time could prevent exacerbations from developing.

However, "unexpectedly, colds did not cause as many asthma exacerbations as were predicted in this clinical trial population," said Synairgen's Professor Stephen Holgate. "We hope to learn from the results of this trial which population within severe asthma, or other respiratory diseases, will most benefit from AZD9412 and should be included in future trial," he added.

"The interim analysis confirmed the positive safety and tolerability profile seen in previous trials, and inhaled IFN-b remains an interesting treatment opportunity for patients with respiratory disease," AZ noted, adding that it will now review all the data and study design before "deciding on the best way forward for the programme."

In evaluating the data, the firm will now focus on the secondary endpoints that are most predictive of disease worsening to exacerbation, with full results expected in the first quarter of next year.