US trials of Pollinex Quattro placed on hold by FDA

UK-based specialist pharmaceutical company Allergy Therapeutics says that clinical studies of its Pollinex Quattro range of allergy vaccines have been suspended by the US Food and Drug Administration while it investigates the occurrence of a rare adverse event, classified by the physician involved as "possibly relevant" to the study.

Further details of the adverse event in question were not provided. However, the Interactive Investor web site reported that a patient in one of the firm's two ongoing Phase III studies displayed "neurological symptoms such as numbness and weakness" but has since gone on to make a full recovery. Allergy Therapeutics said that it was collaborating fully with the FDA and has provided extensive data, including the results of an independent expert assessment. The firm added that it considers it unlikely that its drug had caused the reaction.

In response to the news, Allergy's share price fell 22.7% to 92 pence in afternoon trading on London's Alternative Investments Market. Observers said that this reflected concerns that any regulatory delay was likely to be detrimental to the firm's performance.