BioWorld International Correspondent

LONDON - Shares in Celltech Group plc closed down 10 pence Monday at £2.50 after partner Merck & Co. Inc. said it was stopping development of its lead phospodiesterase-4 inhibitor, discovered by Celltech.

The compound, an oral treatment for asthma and chronic pulmonary obstructive disease, entered Phase II trials in December 2001. Merck has said it will continue to work on PDE-4 inhibitors, but "the timing for the development of these other molecules is not certain."

Peter Allen, chief financial officer of Celltech, told BioWorld International the trial had been stopped because one patient (in several hundred) developed colitis, which resolved once the treatment stopped.

"We are a bit disappointed, but very pleased that [Merck's] enthusiasm for the PDE-4 program is not diminished," Allen said.

There will be a meeting with Merck executives next week to discuss future plans. Allen said his understanding is that the follow-up compound is already in Phase I. "We are certainly going to lose 18 months to two years, and a milestone due at the end of this year, beginning of next, won't be received."

Celltech, based in Slough, is entitled to high royalties on sales and also has an option to take a share of future profits by contributing to Phase III development costs. The collaboration with Merck was signed in 1994. An earlier compound, CDP840, also failed in Phase II trials. CDP840 was a first-generation PDE-4 inhibitor, which like other compounds in its class caused the limiting side effect of nausea and emesis. Celltech has high hopes for the second-generation compounds because they do not have that side effect.