Circassia has slumped at the Phase 2 clinical trial stage again, after its failure with a treatment for those with an allergy to cats. At that point, back in June 2016, it cancelled further development of its synthetic peptides to provide relief of allergy symptoms until it had received results from a dust mite allergy trial. The results are in and they are not good for Circassia.

The Phase 2b trial into patients’ suffering an allergic reaction to house dust mite flopped against the placebo control, similar to that experienced by its treatment for cat allergies. Patients who received a placebo experienced a substantial reduction in Combined Score against the baseline of 39.1%; whilst those who were given its investigational immunotherapy had results ranging from 34.9% to 44.3% against the baseline.

This means that the placebo outperformed lower doses of the drug and the higher end of drug dosing was not enough to display a significant improvement. In a statement, Circassia said that it would no longer be developing its allergy treatments further and would focus on its respiratory pipeline instead.

Steve Harris, Circassia’s Chief Executive, pinned the failure down to the strong placebo effect experienced during both allergy trials: "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."