The U.S. Food and Drug Administration (FDA) has approved the biologic ustekinumab (Stelara) – alone or with methotrexate – for the treatment of moderate to severe psoriatic arthritis (PsA) in adult patients. The expanded indication for Stelara – which was approved in 2009 for the skin disease psoriasis – gives PsA patients who haven’t responded to existing treatments a new option.

An estimated 30 percent of people with psoriasis develop PsA, a chronic inflammatory type of arthritis that involves painful, swollen joints in addition to the skin condition. PsA is treated with nonsteroidal anti-inflammatory drugs (NSAIDs), corticosteroids and disease-modifying antirheumatic drugs (DMARDs) such as methotrexate. The biologics adalimumab (Humira), etanercept (Enbrel), golimumab (Simponi) and infliximab (Remicade) also are used to treat PsA. Known as anti-TNFs, these biologics work by blocking tumor necrosis factor-alpha, a molecule involved in inflammation.

Unlike anti-TNFs, ustekinumab targets two other molecules involved in inflammation, interleukin-12 (IL-12) and interleukin-23 (IL-23).

Joseph F. Merola, MD, co-director of the Center for Skin and Related Musculoskeletal Diseases at Brigham and Women's Hospital in Boston says some patients don’t do well with available drugs, so he is glad to have another choice. “It’s not uncommon at all for us to see patients who have been through several first-line therapies and hit a wall when we run out of options, so it’s important for us to have new treatments,” he says.

New research shows many psoriatic arthritis patients are undertreated.

The FDA based approval of this medication on two phase III, randomized, double blind, placebo-controlled trials of more than 900 patients. The study participants had at least five tender and swollen joints and high levels of C-reactive protein (a measure of inflammation), and weren’t responding to current therapies. They were given either 45 milligram (mg) or 90 mg injections at the start of the trial, four weeks later, and every three months after that for 40 to 88 weeks, depending on the trial they were involved in.

In one study, at six- and 12-month checkups, 50 percent of those receiving the higher dose and 42 percent on the lower dose had at least a 20 percent improvement in symptoms, as measured by American College of Rheumatology criteria. Similar numbers were seen in the other trial.

Dr. Merola, who specializes in rheumatology and dermatology, says these studies showed the many ways ustekinumab could help PsA patients with symptoms ranging from joint pain and dactylitis (the inflammation of an entire finger or toe, known as “sausage digit”) to skin and soft tissue problems.

He also says the dosing regimen is likely to appeal to patients; after two starter doses, it’s given roughly once every three months. Its side effects, including a higher risk of infection, are similar to those of other biologics.

Dr. Merola doesn’t believe this will be a first-line drug for PsA patients – until doctors learn more about how well it works in this group in the long-term. And he also doesn’t see patients switching to it if they're doing well. “I don’t think anyone will stop their current therapy…  but I suspect this will be a very solid second-line agent,” he says. 

“It is very positive to have new things to offer people who have been through other treatment options and failed them, or who were on medications that worked but their efficacy is starting to wane,” he says.