A Phase III program in Crohn's disease is under way to evaluate a compound being developed by Celltech Group plc.

The Slough, UK-based company said it began dosing patients late last month in the first of two planned pivotal trials, with the second study scheduled to begin later this month. In total, the two international trials are expected to enroll more than 1,300 participants in order to assess the ability of CDP870 to induce and maintain a clinical response in patients with moderate to severe Crohn's.

"We're looking at the Crohn's disease activity index scoring system, with a primary endpoint of a 100-point reduction in the index," Richard Bungay, Celltech's director of corporate communications, told BioWorld Today. "We haven't specified the time points, but the study also will include both acute and chronic endpoints."

The studies, named PRECISE (PEGylated Antibody Fragment Evaluation in Crohn's Disease: Safety and Efficacy) I and II, are scheduled to last throughout the year. Though the trials are of a similar size, one will examine the product in a broad population of Crohn's patients, while the other will evaluate it in those with elevated levels of C-reactive protein (CRP) upon entry to the study.

"The findings of our Phase II study showed a better response rate for patients who had elevated CRP levels," Bungay said, noting that a retrospective look at a study of Antegren (natalizumab, Biogen Idec Inc. and Elan Corp. plc) also revealed an improved response among such a patient population. "We really want to determine in the Phase III study whether this observation is correct, and whether, in fact, you can target the drug to patients who are going to respond using these CRP levels."

CDP870 uses Celltech's PEGylated antibody fragment technology to target TNF-alpha, a mediator of inflammation common to conditions such as Crohn's disease, rheumatoid arthritis and psoriasis. The product also is being studied in rheumatoid arthritis, an indication that had been partnered with Pfizer Inc. before the New York-based pharmaceutical giant abandoned the partnership two months ago. Celltech said Pfizer was seeking a larger part of the drug's potential commercial value.

Bungay said the company is entertaining other possible licensing deals for rheumatoid arthritis. But Celltech, which expects to file regulatory submissions next year, plans to market the subcutaneously injected antibody internally with its gastroenterology-focused sales force in the U.S. and other specialty sales forces in Europe.

The only other biologic-based drug approved for Crohn's disease, Remicade (infliximab, Centocor Inc.), is delivered by infusion at a doctor's office. The anti-TNF drug also is approved for rheumatoid arthritis.

Celltech originally partnered CDP870 in March 2001 through a deal with Peapack, N.J.-based Pharmacia Corp., which later merged with Pfizer. The agreement held up to $280 million in promise for Celltech, with $50 million up front.

Outside of CDP870, the company's pipeline includes several early stage clinical candidates - CDP484, an antibody product being developed for rheumatoid arthritis; CDP323, an oral small molecule for multiple inflammatory conditions; CDP791, an oncology-focused antibody designed to interact with the VEGF pathway; and CMC544, an antibody-targeted toxin partnered with Madison, N.J.-based Wyeth for non-Hodgkin's lymphoma.