Amevive's pole position
The debilitating and disfiguring nature of severe psoriasis mandates treatment, but the acute toxicity or inconvenience associated with current therapeutics leaves many patients and dermatologists with unsatisfactory options. While doctors are eager to use Biogen Inc.'s Amevive, which has received a complete response letter from FDA, and quickly use what little Enbrel they can get from Immunex Corp., no one drug seems primed to dominate the market.
Indeed, different dosing regimens and different mechanisms of action imply that different patients still will benefit from existing drugs, as well as from biologics like Amevive, Enbrel, Xanelim and Remicade. And the novelty of biologics in a field unaccustomed to them may relegate these compounds to second, or even third line, therapy in the near term.
The May meeting of the FDA's Dermatologic and Ophthalmic Drugs advisory committee, which recommended approval of Amevive alefacept from Biogen (BGEN, Cambridge, Mass.), pointed up both the serious nature of the disease and the unsatisfactory nature of existing therapies.
The exact cause of psoriasis is unknown, but most researchers have concluded that it is related to the immune system. In psoriasis, the immune system is somehow triggered, which in turn speeds up the growth cycle of skin cells. A normal skin cell matures in 28 to 30 days and is shed from the skin's surface unnoticed. But a psoriatic skin cell takes only 3 to 4 days to mature and move to the surface, and the cells pile up and form elevated red lesions.
About 4.5 million patients have the condition. Of these, "anyone who is disabled by the disease is considered to have severe psoriasis, and there are about 1.5 million people with severe psoriasis for which no real standard of treatment exists," said Steve Feldman, professor of dermatology at Wake Forest University Baptist Medical Center.
"It is important to point out that the severity of this disease can even be surprising to dermatologists," he added. "Suicidal thoughts are not uncommon."
But current treatments are either very inconvenient or have life threatening side effects, or both. Some can only be used for limited periods. And none provide a cure (see "Multiple Drugs, Multiple Targets," A5).
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