LONDON - Celltech Chiroscience plc released data from its first Phase II study of CDP 870, its anti-tumor necrosis factor antibody for treating rheumatoid arthritis, that showed rapid and sustained benefit from the treatment.

The Slough, UK-based company has developed a proprietary method for producing antibodies by fermentation in E. coli, which it says reduces manufacturing costs by 90 percent compared to mammalian cell culture. It expects this cost advantage will enable CDP 870 to be used to treat a broad group of patients, including those with moderate disease.

CDP 870 has not been partnered, and the company intends to continue to develop and then market the drug itself. CEO Peter Fellner said, "In the context of our proposed merger with Medeva, this product represents a significant value retention opportunity."

In November, Celltech Chiroscience announced plans for an all-share takeover of the quoted UK pharmaceutical company, Medeva plc. One of the main justifications was the need to acquire a marketing structure, enabling Celltech to sell its own products.

CDP 870 is modified by PEGylation to have a prolonged half-life. In the Phase I study, the plasma half-life was 11 days, with no significant immune response.

The Phase II study was a dose-ranging, double-blind, placebo-controlled trial in four UK centers. Thirty-six patients with active rheumatoid arthritis received either placebo or one of three doses of CDP 870 administered intravenously. Disease activity was assessed using the standard ACR20 (American College of Rheumatology) score.

The company said all dosages of CDP 870 produced a rapid improvement that lasted throughout the eight-week assessment period, as determined by all disease activity parameters. The treatment effect was statistically significant, it said. CDP 870 was well tolerated, and its lack of immunogenicity confirmed.

Ninety percent of the patients have entered a subsequent open phase of the study, and received a second dose. Data will be available early next year.

Celltech Chiroscience said it is planning a large Phase IIb study that will begin in the first half of 2000. This will consist of an initial three-month placebo-controlled phase, followed by a nine-month open study. n