Pfizer rheumatoid arthritis drug effective in study

By Lewis Krauskopf

NEW YORK (Reuters) - Pfizer Inc's experimental pill for rheumatoid arthritis appeared to be effective and well-tolerated in a mid-stage clinical study, the drugmaker said.

The drug, known as CP-690,550, achieved the main goal of 20 percent improvement (ACR 20) of symptoms after 12 weeks in patients suffering from the painful joint-swelling condition at all but one of the tested doses.

Significantly more patients reached the ACR 20 goal on the medicine than did those who received a placebo.

Data from the interim analysis of the 509-patient, 6-month study were to be presented next week at the American College of Rheumatology meeting in San Francisco.

Rheumatoid arthritis is an auto-immune disease, whose cause is unknown, but leads to pain, swelling and loss of function in joints. It affects 2.1 million Americans, according to the Arthritis Foundation.

Although several years away from potentially reaching the market, CP-690,550 is part of a new class of rheumatoid arthritis therapies that could be more convenient for patients who must take most current medicines by injection or infusion.

The medicine's development also is being closely watched by stock analysts and investors, who are concerned that Pfizer lacks sufficient drugs in its experimental pipeline to make up for expected revenue declines when its Lipitor cholesterol medicine loses U.S. patent protection in 2011.

CP-690,550 arguably is Pfizer's most important mid-stage product, JP Morgan analyst Chris Schott said in a research note last month.