Shares in Belgium’s UCB are suffering this morning after the company revealed that further studies are to be conducted on its potential blockbuster Cimzia which will mean a long delay before any launch can be considered.

UCB said that it has decided to initiate “an additional short-term clinical study” of Cimzia (certolizumab pegol) to confirm the induction of clinical response” in moderate to severe active Crohn's disease. The news followed a meeting with the US Food and Drug Administration held this month in response to a letter the agency sent to the firm in December requesting additional information and clarification on data submitted in the Cimzia application.

UCB now says it will work closely with the FDA to finalise the design of the new clinical study in order to provide additional clinical efficacy data. It added that it will fully reply to the agency’s December letter by the end of April and noted that the FDA had raised no major issues or concerns around the safety of Cimzia or relating to chemistry, manufacturing and controls “but did question the adequacy of one study design.”

More worrying for UCB is that the results from this additional clinical study with Cimzia in Crohn's disease will not be known until the second half of 2008. The company still plans to file a Biologics License Application with the FDA for Cimzia in the treatment of rheumatoid arthritis by year-end 2007 but analysts believe that the big money will come with an approval in Crohn’s. The news of the delay comes just a month after Abbott Laboratories' rival drug Humira (adalimumab), was approved for the indication in the USA.

Roch Doliveux, UCB’s chief executive, was still upbeat and said that "we have complete confidence in Cimzia's robust efficacy and competitive safety,” adding that the drug “will be, at launch, the first anti-TNF which is a PEGylated and Fc-free antibody fragment.” The importance of the drug to UCB’s future growth is considerable, especially as it will lose patent protection on its biggest earners – the allergy drug Zyrtec (cetirizine) and the antiepileptic Keppra (levetiracetam) – in 2007 and 2009 respectively.