Circassia shares plummet following cat allergy therapy failure

Circassia Pharmaceuticals’ cat allergy immunotherapy has failed in a phase 3 study, sending the UK biotech’s shares tumbling.

Shares nosedived from almost 268p per share to less than 100p per share this morning, as the company said the failure could have implications for its other products under development.

The company will also stop a recently initiated registration study of its grass allergy treatment, as well as preparatory work for a dose-ranging study of its ragweed allergy therapy.

Announcing top-line results, the company said the failure was due to a “very marked” placebo effect, although it noted the drug was well tolerated with a highly favourable safety profile.

A phase 2b study of a house dust mite allergy product is well advanced and Circassia said it will assess whether to continue the trial. A birch allergy product is nearing completion of a phase 2 study, which will continue.

Circassia’s CEO, Steve Harris, said the Oxford-based firm would “rapidly analyse” results and provide an update on the development plans for its broader business in interim results.

The study compared a four-dose course of Fe1 d 1 allergen peptides, two sequential courses (eight doses) and placebo.

Primary endpoint was the mean combined score (combined total rhinoconjunctivitis symptom score – TRSS – and rescue medication use score). Mean TRSS was a secondary endpoint measure.

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

Placebo and treatment groups had greatly improved combined score vs baseline and all groups had greatly improved TRSS versus baseline.

The combined score in the active treatment groups were not significantly different to placebo, Circassia said.

Harris said: “We are surprised and disappointed by these results. Such a dramatic placebo effect was not a feature of our earlier phase 2 studies.”

The company will continue its focus on maintaining strong sales growth in its NIOX asthma management franchise and establishing its specialty commercial infrastructure in the US and Europe. Circassia will also continue to progress its respiratory portfolio.

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