A new manufacturer-funded study on the psoriatic arthritis drug Stelara shows it can block joint damage in six months and continue working after two years.

Janssen Biotech, Inc. says clinical trials they’ve sponsored show the drug Stelara is effective at slowing the progression of joint damage caused by psoriatic arthritis.

Stelara (ustekinumab) has been on the U.S. market since 1999 after receiving approval from the U.S. Food and Drug Administration (FDA) to treat moderate to severe psoriasis. It was approved in September to treat psoriatic arthritis.

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Dr. Arthur Kavanaugh, Director of the Center for Innovative Therapy at the University of California, San Diego School of Medicine, and co-principal study investigator, said ustekinumab has led to improvement across multiple areas of psoriatic arthritis disease activity, including skin and joint tissue damage.

“Now there is data suggesting efficacy inhibiting the progression of joint damage as assessed on X-rays,” he said in a statement.

Psoriatic arthritis—characterized by painful inflammation in the joints—was most notably showcased in the British television show “The Singing Detective,” and a 2003 Robert Downey Jr. movie of the same name. It affects the joints and skin, leading to joint damage and disability if left untreated.

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Stelara is an immunosuppressant drug, meaning that it dampens the body’s entire natural immune response. Since psoriatic arthritis and other conditions, such as psoriasis and rheumatoid arthritis, are believed to be caused by an overactive immune system, immunosuppressant therapies can help control body-wide symptoms.

Other immunosuppressant therapies approved to treat psoriatic arthritis include azathioprine (Azasan and Imuran), cyclosporine (Neoral, Sandimmune, and others), and Leflunomide (Arava).

The latest findings from Janssen’s phase-3 trials—which were multicenter, randomized, double-blind, placebo-controlled and involved 927 patients—show that Stelara can block damage to joints in patients with active psoriatic arthritis.

The trials used both 45 mg and 90 mg doses of Stelara, depending on the progression of a given patient’s disease. Those who took a placebo and showed no change in disease activity after four months then began Stelara treatments.

Less than six percent of trial patients experienced adverse events, and after a year of therapy, the safety profile of the treatment group and placebo group were nearly identical.

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However, suppressing the immune system leaves the body vulnerable to other complications. The serious side effects of Stelara, according to an FDA fact sheet, include the risk of serious infections, certain cancers, serious allergic reactions, and the potentially fatal brain condition known as reversible posterior leukoencephalopathy syndrome.

The Stelara announcement didn’t specify which side effects patients experienced during the trials.

Dr. Philip Helliwell of Arthritis Research U.K., told the American College of Rheumatology Congress in San Diego that people with psoriatic arthritis see better outcomes with early, aggressive drug treatment.

Because better drug treatments are now more available than in the past, Dr. Helliwell said earlier, intensive treatment of the condition can reduce joint damage more effectively and help prevent disability.

“We have found that tight control of disease activity in psoriatic arthritis, using a targeted approach, significantly improves the joint and skin outcomes for newly diagnosed patients with no unexpected side effects,” he said.

Helliwell and his colleague Dr. Laura Coates spearheaded a U.K. clinical trial involving more than 200 patients. They found that more aggressive treatment—in which patients are given escalating drug dosages and see a specialist every month—leads to better outcomes within one year than a less aggressive course.

“These findings could have significant implications for the way that this common type of inflammatory arthritis is treated and controlled,” Helliwell said.