The FDA has approved ustekinumab (Stelara) for the treatment moderate-to-severe psoriatic arthritis in adult patients, drugmaker Janssen Biotech announced Monday.

The approval was based on the findings of two phase III studies of this fully human monoclonal antibody, which targets two cytokines, interleukin (IL)-12 and IL-23.

"It is critical for dermatologists and rheumatologists to be able to offer new and novel treatment options to our adult patients living with psoriatic arthritis, a disease where additional biologic options are very much needed," study investigator Alice B. Gottlieb, MD, of Tufts University in Boston said in a statement.

The trials included 927 patients who had at least five tender and swollen joints and elevated C-reactive protein despite conventional therapy and/or previous biologic treatment with tumor necrosis factor (TNF) blocking agents.

They were treated with either 45 mg or 90 mg of ustekinumab subcutaneously at baseline and after 1 month, and every 3 months thereafter.

In the first study, known as PSUMMIT 1, 42% of patients given the lower dose had a 20% improvement in symptoms according to the criteria of the American College of Rheumatology (ACR20) after 6 months, as did 50% of those receiving the higher dose.

The responses persisted for an additional 6 months.

In the second trial, PSUMMIT II, 44% of patients in each dose group had an ACR20 response at 6 months. In that study, presented in June at the annual meeting of the European League Against Rheumatism, even among patients who had previously received anti-TNF treatment, 50% to 55% showed ACR20 responses.

The treatment not only alleviated the joint symptoms, but also improved the associated skin and soft-tissue manifestations of psoriatic arthritis.

The approval "marks the first treatment approved for this devastating and complex disease since the introduction of anti-TNF biologic medicines more than a decade ago," said Jerome A. Boscia, MD, of Janssen Research & Development, in the press release.