British biotech Circassia has announced the death of its allergy programme following a second key trial failure, choosing to focus all of its efforts on its respiratory business instead.

The company said it would make “no further investment” in its allergy portfolio after a Phase IIb assessing its investigational house dust mite allergy immunotherapy failed to show a significant effect compared with placebo.

In the study, both the active treatment and placebo greatly reduced subjects’ allergy symptoms and rescue medication use, which was pretty much the same outcome of a Phase III study assessing its experimental immunotherapy for cat allergy last year.

“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,” said Steve Harris, Circassia’s chief executive.

“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,” he said, further explaining the decision.

Circassia said it would now focus on its wider respiratory business, in particular its new US commercial collaboration with AstraZeneca, its NIOX franchise and the development of its broader respiratory portfolio.