Enbrel acts like a very specific sponge that soaks up only one thing: a chemical messenger called tumor necrosis factor or TNF. TNF plays a major role in psoriasis by triggering inflammatory, skin-damaging, arthritis-causing immune responses.
Because TNF also helps the body fight off infection and cancer, there have been nagging worries that safety problems might arise in patients on long-term Enbrel treatment -- especially those who need higher doses. Also, doctors wondered whether the drug's psoriasis-easing effects would wear off over time.
To answer these questions, Stephen Tyring, MD, PhD, of the University of Texas Health Science Center at Houston and colleagues signed up 618 adult psoriasis patients for the study.
To enter the study, patients had to have at least "moderate" psoriasis -- that is, psoriasis affecting 10% of their body surface. Study patients tended to have much more severe disease, with an average 27% of their body surface affected. also, at least one systemic psoriasis treatment or phototherapy had to have failed to help.
Patients received twice-weekly injections (under the skin) of Enbrel at the 50-milligram dose for 96 weeks -- nearly two years. Half the patients received placebo injections for the first 12 weeks of the study. After that, everyone in the study got Enbrel.
The results: At week 96, half the patients in both groups had at least a 75% reduction in psoriasis severity without any increase in infections or other serious diseases.
Enbrel: Safe & Effective So Far
"Safety is always of utmost concern," Tyring tells WebMD. "We saw no increased risk of heart attacks or anything else. And safety did not appear to be a problem in terms of cancers or malignancies."
A main question for long-term Enbrel treatment is whether its effects wear off for patients who take high doses for a long time.
"The answer is, psoriasis clearance was maintained," Tyring says. "The bottom line is that all of this is an understatement. In real life we rarely tell patients, 'Just use this Enbrel and that is it.' We use these psoriasis medications in combination -- a topical solution on the legs or scalp, and also light therapy. When we do that, we see efficacy far beyond that noted in the study."
University of Miami researcher Jonette Keri, MD, PhD, chief of dermatology at the Miami VA Hospital, says she has patients whose psoriasis flares up unless she keeps them on the high doses of Enbrel used in the Tyring study.
"This study should give some reassurance to patients that they are not at any higher risk of cancer if they take Enbrel long term," Keri tells WebMD. Keri was not involved in the Tyring study but will be one of the investigators in another long-term study of Enbrel.
Keri notes that patients taking Enbrel should remain alert for symptoms of any of the drug's rare side effects. Most of these adverse events, she says, can be identified well before any lasting harm occurs. Side effects include serious infections, nervous system disorders, and blood disorders.
"We don't know the effects of years of use, but Enbrel has been used to treat arthritis for years," Keri says.
Tyring notes that about a third of psoriasis patients suffer psoriasis-associated arthritis. Enbrel, he says, is particularly helpful in relieving this condition. Keri agrees.
"The good thing is that with the arthritis, patients feel good in a week or so," she says. "And over the next four or five or six weeks, their skin catches up and starts to look better. For some people it is absolutely great. But it is a very expensive medicine, and the higher does will cost more."
Psoriasis is a chronic skin condition characterized by thick red, silvery, white skin patches. It often affects the skin of the scalp, elbows, and knees. Who should take Enbrel for psoriasis?
"It is not for everybody, but Enbrel is particularly helpful for psoriasis patients with joint involvement, those with extensive skin involvement, those whose psoriasis affects inhibits daily function, and those who have not had success with other therapies," Tyring says.
Tyring and colleagues report their findings in the June issue of Archives of Dermatology.
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