- Top-line results from Circassia Pharmaceuticals' investigational house dust mite allergy immunotherapy phase IIb field study failed to achieve to its primary endpoint.

Circassia said that in the study, both the active treatment and placebo greatly reduced subjects' allergy symptoms and rescue medication use.

As a result, the treatment did not show a significant effect compared with placebo and the study did not meet its primary endpoint.

But it said the results showed the immunotherapy was well tolerated with a highly favourable safety profile.

Chief executive Steve Harris said: "We are naturally disappointed by this outcome, which is in line with our cat allergy phase III study where there was also a very marked placebo effect.

"Although subjects receiving the immunotherapies in both these studies had greatly improved allergy symptoms, the strong placebo effect made it highly challenging to achieve the studies' endpoints.

"It is concerning that in two well-designed field trials, a robust placebo response has confounded our ability to demonstrate a significant treatment effect, despite positive results in earlier chamber studies.

"We remain convinced that the technology has biologic activity, but we also believe the difficulty in overcoming the placebo effect using the field study designs required by regulators represents a significant hurdle, and consequently we will make no further investment in our allergy portfolio.

"As indicated previously, we will now focus on our wider respiratory business, in particular our new US commercial collaboration with AstraZeneca, our market-leading NIOX franchise and the development of our broader respiratory portfolio."

Story provided by