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Rheumatoid arthritis drug in trials for psoriasis and psoriatic arthritis

A biologic drug recently approved for the treatment of moderate to severe rheumatoid arthritis is now being studied for psoriasis and psoriatic arthritis.

Adalimumab (brand name Humira) is a biologic that blocks a protein that plays a role in the development of psoriasis and psoriatic arthritis. Humira�s effectiveness for these diseases has not been tested, so the drug�s manufacturer, Abbott Laboratories, is starting two clinical trials. In a phase II trial, adult patients with moderate to severe plaque psoriasis will be evaluated for improvements in their disease, and a larger phase III trial will measure whether the drug improves people's psoriatic arthritis and psoriasis.

It will probably be several years before these studies are concluded and, pending the outcome, Abbott seeks approval from the U.S. Food and Drug Administration (FDA) to treat psoriasis and psoriatic arthritis with Humira.

The FDA approved Humira in December 2002 for patients with moderate to severe rheumatoid arthritis who have had insufficient response to one or more standard therapies, such as methotrexate. The drug blocks a protein called tumor necrosis factor-alpha (TNF-alpha), which plays a role in the inflammatory responses of autoimmune diseases such as rheumatoid arthritis. Patients give themselves injections under the skin every other week at home.

More than 2,000 rheumatoid arthritis patients were involved in clinical trials for Humira. In a 24-week study of 271 patients who hadn't responded to at least one standard treatment, patients who received 40 milligrams (mg) of Humira achieved higher improvement responses one week after starting therapy than those on methotrexate and placebo.

The degree of improvement was sustained during the six-month trial: more than 65 percent of patients achieved 20 percent improvement; more than half improved by 50 percent; and nearly 25 percent improved by 75 percent. The rates of improvement were sustained throughout one-year and three-year studies.

TNF inhibitors, like all medications, have side effects. The most frequently reported adverse effects were upper respiratory infection, injection-site pain, rash, headache and sinusitis. The effects were similar to those on placebo and methotrexate. The most serious effects included tuberculosis, serious infections, sepsis, lymphoma and exacerbation of demyelinating disease, in which the protective fatty protein that sheaths nerve cells (neurons) is destroyed. Because of the risk of infections, patients are tested for latent tuberculosis, and physicians exercise caution with those with a history of infections. Treatment is discontinued in patients who develop infections.