Biologics gaining ground against psoriasis

Enbrel (etanercept, Amgen/Wyeth) remains the only biologic drug approved by the U.S. Food and Drug Administration (FDA) for treating psoriatic arthritis. It's also FDA-approved for illnesses including rheumatoid arthritis (RA), ankylosing spondylitis and psoriasis.

"In regard to psoriatic arthritis," says Jeffrey M. Weinberg, M.D., "it inhibits the progression of destructive changes. As our current drugs go, if you're treating psoriatic arthritis, etanercept is the clear choice." He is assistant clinical professor of dermatology at Columbia University and director of the Clinical Research Center at St. Luke's-Roosevelt Hospital Center, New York.

Remicade (infliximab, Centocor), an IV infusion drug currently undergoing phase 3 testing, already has shown impressive efficacy in phase 2 results. As such, its maker has filed for FDA approval in treating psoriatic arthritis.

A recent multicenter, double-blinded, placebo-controlled trial involving 249 patients with severe plaque psoriasis showed that after 10 weeks, 72 percent of patients treated with three mg/kg (at weeks zero, two and six) and 88 percent of those treated with five mg/kg reached PASI 75 or higher. In both groups, improvement was seen in as few as two weeks, although nearly 80 percent of patients in these groups reported at least one adverse event (Gottlieb AB et al. J Am Acad Dermatol. 2004;51:534-542.).

"Of all the biologics, infliximab seems to have the highest efficacy," Dr. Weinberg says. "But it also seems to be associated with the highest number of side effects, including an increased risk of infection and possibly an increased risk of tuberculosis. And recently, its label was changed to address a threefold increased risk of lymphoma in patients with RA and a sixfold increase of lymphoma in patients who have both RA and Crohn's disease who are treated with Remicade (although all TNF inhibitors carry similar warnings)."

Humira (adalimumab, Abbott), which recently entered phase 3 trials for psoriasis, appears to achieve an efficacy level between that of etanercept and infliximab. In phase 2 testing, researchers treated 148 adults with moderate to severe chronic plaque psoriasis for at least one year and at least 5 percent of their body surface affected. They gave patients not in a placebo group 40 mg either weekly or every other week (after an 80 mg initial dose).

At six months, 72 percent of the 40-mg-weekly group and 64 percent of the 40-mg-every-other-week group had achieved a PASI 75 response. (Wallace K et al. Poster presented at: Summer Academy 2004 of the American Academy of Dermatology; July 28 - August 1, 2004; New York, New York, Poster 78.).

"The advantage of adalimumab is that it's usually administered every other week," Dr. Weinberg says. "What we have for etanercept and we don't have for adalimumab yet is long-term safety data. We've had many patients on etanercept for RA for six or seven years. Adalimumab is a newer drug, and dermatologists are eager to see if the long-term safety of this drug will match that of etanercept."