Circassia plummets after cat allergy drug fails placebo test

Shares in biopharmaceutical development company Circassia Pharmaceuticals plummeted on Monday morning, after it announced disappointing top-line results from its investigational cat allergy immunotherapy phase III study.

At 0815 BST, shares in Circassia were down 55.86% at 119.3p.

The FTSE 250 firm said that in the study, both of its developmental treatments as well as the placebo greatly, and equally, reduced test subjects’ combined allergy symptoms and rescue medication use score from baseline.

As a result of the “very marked” placebo effect, the treatment did not meet the study’s primary endpoint, Circassia’s board reported.

It added that the treatment was still well-tolerated with a highly favourable safety profile, despite the results.

“We are surprised and disappointed by these results,” said Circassia chief executive Steve Harris.

“Such a dramatic placebo effect was not a feature of our earlier phase II studies.

“However, in this large-scale trial it eliminated the ability to identify a treatment effect despite dramatic improvements in subjects' allergy symptoms and rescue medication use,” he explained.

Harris said the company will now rapidly analyse the full dataset, address the implications for its wider allergy pipeline and provide an update on the development plans for its broader business at its interim results.

“At the same time, we will continue to focus resolutely on our wider portfolio, rapidly growing the sales of our market-leading NIOX asthma management products and advancing our pipeline of respiratory products,” Harris said.

The study compared a four-dose course of Fel d 1 allergen peptides, two sequential courses totalling eight doses, and placebo.

Circassia’s primary endpoint measure was the mean Combined Score, meaning combines total rhinoconjunctivitis symptom score and rescue medication use score.

The study’s endpoint outcomes were the difference between placebo and active groups one year after the start of dosing.