A drug used to treat Crohn's disease and rheumatoid arthritis may improve both the skin condition and arthritis symptoms in patients with psoriatic arthritis, according to studies released at the American College of Rheumatology's annual scientific meeting last week.
About 1 million people, or 23 percent of those with psoriasis, have the accompanying form of arthritis, which usually shows up about 10 years after the onset of psoriasis. And 40 percent of people who develop the arthritis will in their lifetime develop some degree of disability from it, said Dr. Gerald G. Krueger, of the University of Utah Department of Dermatology and one of the lead study investigators. The most common are inability to move fingers and toes at all.
While it's most easily recognized in the joints of the fingers, hands and toes, psoriatic arthritis can also show up as a "migrating arthritis" that appears in the larger joints like the knees, shoulders, elbows and hips. Sometimes it's hard to distinguish from other conditions, such as one where arthritis in the spine forms a solid bone mass.
"It has a wild spectrum of presentation that, interestingly enough, all seem to be mediated by drugs that neutralize tumor necrosis factor," which is precisely what the drug infliximad, brand name Remicade, does. The treatment, produced by Centocor, is given in a doctor's office or clinic as an IV injection.
For the study, patients received the drug or a placebo periodically over a period of six months, Krueger said.
The drug seemed to stop the structural progression of the arthritis and appears to reverse existing damage, though more study is needed on that, Krueger said. It also produced remissions in both skin and arthritis symptoms.
Centocor says Remicade is a monoclonal antibody that targets and binds to tumor necrosis factor-alpha on the cell membrane and in the blood. Production of TNF-a is believed to play a role in rheumatoid arthritis, Crohn's disease and in many other immune-mediated inflammatory disorders, such as psoriatic arthritis. Remicade is being studied to treat several of them.
Enbrel, already on the market to treat psoriasis, is also a TNF neutralizer. Another, Humira, is being tested. They are all a little different, with different strengths, Krueger said, adding only recently have treatments tackled the psoriatic arthritis at all. Efforts were limited to controlling symptoms like inflammation and pain.
Many of the treatments have worked modestly, if at all, he said.
The European Commission in September approved expanded labeling for Remicade in combination with methotrexate as a treatment for both active and progressive psoriatic arthritis.
Since the drug could be used for the psoriatic arthritis as an "off-label" use in America, Centocor doesn't have to seek separate approval to call it a medication for PA, Krueger said. But it will, because many insurance carriers won't pay for a drug that's used for something for which it has no specific approval.
That approval, if all goes as expected, could come in as little as six months, he said.
Not everyone can use it. People may be allergic to a particular component. Those with tuberculosis should not use it, nor should anyone with an active infection of any type, especially if they're being treated with antibiotics. People with MS or who have symptoms of MS should not try it. It can also "activate diseases that the body sometimes keeps in check" such as listeriosis. People with congestive heart failure may not be candidates, either.