The first new drug in over a decade for rheumatoid arthritis won the backing of government advisers Friday.

Arava, made by Hoechst Marion Roussel, does not cure crippling rheumatoid arthritis. But it appears to work as well as the gold-standard treatment, a cancer drug, at treating swollen, painful joints. And it appears to slow the progression of the debilitating disease."This drug does good things in joints," said Dr. Kenneth Brandt of Indiana University, before fellow advisers to the Food and Drug Administration recommended unanimously that Arava be approved for sale.

The FDA is not bound by its advisers' recommendations but typically follows them.

Rheumatoid arthritis affects about 2 million Americans, the vast majority of them women.

It is not the kind of arthritis that plagues the elderly as their joints essentially wear out. Instead, rheumatoid arthritis is an autoimmune disease - the immune system goes awry and attacks patients' own cartilage. It typically strikes between ages 25 and 50.

The best treatment today is methotrexate, a cancer drug. But it causes troublesome side effects, and its effectiveness wanes over time, leaving patients with few options.

Arava, known chemically as leflunomide, is the first in a series of promising new treatments now approaching the market, after decades of no new alternatives. It works by blocking the overproduction of immune cells that are responsible for most of the arthritis's inflammation.

Hoechst studied 480 Americans with moderate disease. Some 41 percent of Arava patients saw their arthritis improve, compared with 19 percent of patients taking dummy pills. Methotrexate patients improved about the same as Arava patients.

Then Hoechst took X-rays of patients' hands and feet, studying bone erosion and cartilage disappearance to track the disease's progress. Arava patients did worsen. But in a year of study, placebo patients worsened four times more quickly than Arava patients. Methotrexate also slowed the disease's progression but not as much as Arava did.

Arava did cause side effects in more than one-fourth of all patients, including diarrhea and hair loss. But Arava did not seem as prone to causing the serious problems that methotrexate sometimes can, such as kidney failure, said Dr. Marc Hochberg of the University of Maryland, who monitored the study's safety. Methotrexate also works by blocking immune cells, but targets a different enzyme than Arava to do the job.