Psoriasis is an autoimmune disorder in which faulty immune cells produce inflammation. This inflammation causes skin cells to grow too quickly, which in turn causes the red and flaky lesions characteristic of the disorder. Biologics work by suppressing the immune cells at the heart of this process. One group of biologics, which target a type of white blood cell, are known as the T-cell modulators; the other main group, which target a protein involved in inflammation, are known as the tumor necrosis factor (TNF) inhibitors.
There are currently five biologics approved for psoriasis patients in the United States:
- Humira (adalimumab). Originally used to treat psoriatic and rheumatoid arthritis, Humira was approved for psoriasis in 2008. In long-term controlled trials, between 55% and 70% of the patients taking Humira experienced a 75% reduction in their plaques (a common measure of clearance known as “PASI 75”).
- Remicade (infliximab). Administered via IV in a dermatologists office every eight weeks, Remicade is perhaps the most powerful biologic. The two trials that have studied the long-term efficacy of Remicade report PASI 75 response rates of around 80%.
- Enbrel (etanercept) One of the earliest biologics approved for psoriasis, Enbrel is considered to be relatively safe and well tolerated, although it is less powerful than Humira. Studies report PASI 75 rates ranging from about 45% to 60%.
- Amevive (alefacept). Amevive is the only biologic designed to be used intermittently, in 12-week intervals. Although one study reported PASI 75 rates of nearly 30% at 12 weeks and more than 50% at 60 weeks, the evidence suggests that Amevive may be the least effective biologic in the long term.
- Stelara (ustekinumab). Stelara, which was approved by the U.S. Food and Drug Administration (FDA) in September 2009, is the newest biologic. It is injected just once every three months (after a pair of initial doses four weeks apart). And because it isn't a T-cell modulator or TNF inhibitor, it provides an alternative for patients who haven't responded to other biologics. In clinical trials, Stelara has achieved PASI 75 response rates between roughly 65% and 80%.