Treatment with ustekinumab, an antibody that attacks certain cell messenger chemicals, can reduce the signs and symptoms of psoriasis-related arthritis. The treatment is also well tolerated by patients, according to a report in The Lancet, a prominent British medical journal.

Psoriasis is a condition linked to an overactive immune system that causes inflamed, scaly red patches to form on the elbows, knees, scalp and trunk. In some cases, psoriasis causes arthritis symptoms, such as swollen, stiff, or painful joints.

Dr. Alice Gottlieb, from Tufts Medical, Boston, and colleagues note that there is a need for drugs to treat psoriatic arthritis when standard treatments fail.

Prior research has suggested that cell messenger proteins, called interleukin 12 and interleukin 23, play a role in the symptoms and joint damage seen in patients with psoriatic arthritis, the authors explain, and thus treatment with an agent that blocks these proteins may have a beneficial effect.

The current trial involved 146 patients who were randomly assigned to receive ustekinumab or an inactive “placebo” for several weeks.

At 12-week follow-up, 42 percent of ustekinumab-treated patients showed a meaningful improvement in symptoms compared with 14 percent of those given placebo.

Among 124 subjects with psoriasis affecting 3 percent or more of their body surface area, 52 percent of ustekinumab-treated patients and just 5 percent of those given placebo showed a 75 percent or greater improvement in psoriasis severity and a reduction of the affected area.

Side effects with ustekinumab were no more likely than with placebo and no serious complications were noted with the drug.

The effectiveness of “ustekinumab for improving skin and joint involvement, which was maintained for several months, combined with good tolerability and a benign safety profile, make this agent an attractive option in psoriatic arthritis,” Dr. Raquel S. Cuchacovich and Dr. Luis R. Espinoza, from Louisiana State University Health Sciences Center, New Orleans, comment in a related editorial.

SOURCE: The Lancet, February 12th online, 2009.