* Oral RA drug significantly better than placebo
* ACR 20 tops placebo at all tested doses
* 5 mg and 10 mg to move on to Phase III testing
NEW YORK, June 9 An experimental oral
rheumatoid arthritis drug being developed by Pfizer Inc (PFE.N)
was significantly more effective than a placebo in a mid-stage
clinical trial, according to data to be presented at a medical
meeting in Denmark on Thursday.
The drug, given twice daily, was tested at strengths of 3
milligrams, 5 mg, 10 mg and 15 mg and demonstrated a
statistically significant response at all doses compared with a
placebo, the company said.
Data from a 12-week interim analysis of the six-month study
of the drug, CP-690,550, has been used to help select the 5 mg
and 10 mg doses for larger Phase III clinical trials, Pfizer
said. Phase III is typically the final stage of testing before
a new drug is submitted to the U.S. Food and Drug
Administration for an approval decision.
The primary goal of the study was an ACR 20 response rate,
defined as 20 percent improvement in tender and swollen
At the two highest doses, 75.4 percent of patients achieved
ACR 20 response rates compared with 28.8 percent of those in
the placebo group. The ACR 20 response was 49 percent at 3 mg
and 63.3 percent at 5 mg, according to data to be presented at
the European League Against Rheumatism meeting in Copenhagen.
The differences in response rates were seen as early as two
weeks into the study, researchers said.
The study involved 384 patients with active rheumatoid
arthritis, who had not responded to treatment with another
anti-rheumatic drug, such as methotrexate.
CP-690,550 is a so-called JAK-3 inhibitor that works by
blocking enzymes involved in inflammatory and autoimmune
In addition to the ACR 20 primary goal, there were
statistically significant ACR 50 responses -- 50 percent
improvement -- for the drug at 5 mg, 10 mg and 15 mg, and ACR
70 responses at the two highest doses, compared with placebo,
The most common adverse events were mild to moderate
urinary tract infection, diarrhea, bronchitis and headaches.
Significant dose-dependent decreases in white blood cells
and increases in both good and bad cholesterol were consistent
with previous studies of CP-690,550, Pfizer said.
(Reporting by Bill Berkrot)