The findings, reported this week in the New England Journal of Medicine, may help patients whose extensive psoriasis is not well-controlled to find an alternative treatment.
"I think it's pretty clear that Stelara is a dramatically effective drug, one of the most effective drugs we've ever had for psoriasis," Mark Lebwohl, MD, chairman of the dermatology department at Mount Sinai School of Medicine, tells WebMD. Lebwohl's department was one of 67 sites worldwide to participate in the study.
Both Stelara and Enbrel are biologics -- treatments made up of genetically engineered proteins -- and used to treat patients who have moderate to severe psoriasis that has not responded to traditional systemic therapies such as methotrexate.
But the two drugs have completely different mechanisms of action. While Enbrel blocks tumor necrosis factor-alpha (TNF-alpha), Stelara targets two inflammatory chemicals, interleukin 12 and interleukin 23, which are involved in the pathogenesis of psoriasis.
Study researcher Christopher Griffiths, MD, a professor of dermatology at England's University of Manchester Medical School, says if patients taking Enbrel have well-controlled psoriasis, they need not switch to Stelara.
The study's conclusion "just gives those individuals the reassurance that if for some reason the Enbrel stops working, or wasn't working as effectively as it was at the beginning, that there's a proven, logical alternative therapy that they could switch to."
In the study, 903 patients with moderate-to-severe plaque psoriasis got either Stelara (high or low dose) or high-dose Enbrel.
Comparing Enbrel and Stelara
At week 12 of the study, 65% of patients in the lower-dose Stelara group and almost 71% of those in the higher-dose Stelara group had, at most, minimal signs of their psoriasis, according to their doctors, compared to 49% of patients treated with Enbrel.
"We've never had a drug that with so few injections worked so well," Lebwohl says. Patients in the Sterlara group got one injection when they started the study and another one four weeks later; patients receiving Enbrel received two injections every week for 12 weeks.
Lebwohl says he's not surprised by the study's outcome. "We've been hearing about [Stelara] for years." It has been on the market in Europe and Canada for one year.
The study was sponsored by Centocor, the pharmaceutical company that makes Stelara. Lebwohl has served as an investigator for both Centocor and Amgen, the company that manufactures Enbrel.
Lebwohl's advice to people with psoriasis is to weigh their options. Many patients do well on Enbrel, and it has a long safety track record. Stelara, on the other hand, is more effective than Enbrel, but it has not been around long enough to fully gauge how safe it is, he notes.
Data from the 12-week study found that within this short frame, the safety of the two drugs was generally similar. However, Lebwohl cautions that three months is too short a time to determine if Stelara will eventually increase the risk for infections or cancer. Biologic agents affect the body's immune system, which explains this potential risk.
Sonia Fiorenza, Amgen's director of corporate communications, echoes these safety concerns in an email. Dermatologists' No. 1 concern in treating psoriasis is long-term safety. While Enbrel has an established safety profile with more than 17 years of collective clinical experience, this study does not provide comparative efficacy and safety data beyond three months, she writes.
Psoriasis affects at least 2% of the world's population. For the most part it is a young person's disease, with three-quarters of cases appearing before the age of 40. It is not contagious and there is no cure.
People with moderate to severe psoriasis face significant psychosocial difficulties including depression and isolation. Often they will avoid public places like swimming pools or gyms because even though psoriasis is not contagious, the public perceives it to be so, Griffiths says.
"The advent of the biologic therapies has been life transforming for a lot of patients," he notes.