Last updated: May 19, 2009
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%.
Risk vs. reward
Biologics can be extremely effective at clearing psoriasis, but their immunosuppressive effect also produces a slightly increased risk of infection, including the flu, serious fungal infections, and even tuberculosis. Patients (and dermatologists) should therefore be on the lookout for any warning signs of infection, such as a fever. Some patients taking biologics report a greater susceptibility to colds and other upper respiratory tract infections, but there is some disagreement about whether that can be attributed to the drug itself or merely to patient perception.
Given the impact psoriasis can have on everyday life and happiness, many patients with moderate to severe psoriasis have decided that the prospect of clear skin is worth the small infection risk. And those who have experienced good results with a biologic tend to describe the drugs as something of a miracle cure.
About 25 years ago, Allison Duncan, 48, of Palm Coast, Fla., started to experience psoriasis symptoms that eventually grew more severe. At its worst, 50% to 60% of her body was covered, and in the late 1990s she finally consulted a dermatologist. “I tried treating it with topicals, I tried natural remediesI tried everything in the book,” she says. She even tried bathing in a tub filled with freshly grated ginger, which didnt help her psoriasis but did clog up the pipes.
Six years ago, Duncan was invited to take part in a clinical study for a biologic. Her skin didnt respond for nearly 10 weeks, and she almost quit the study. And then, “literally overnight,” she says, her skin started to clear. Two weeks later she was 100% clear. “Ive never had a spot come back,” she says.
Although Duncans results are exceptional, other psoriasis patients describe similar night-and-day experiences. Nikki Woistman, 21, of St. Petersburg, Fla., started taking a biologic in 2003 after her psoriasis had grown to cover 30% of her body. After two weeks her skin started to clear, and within two months she was 99% psoriasis-free. “I was in heaven,” she says.
Biologics effectiveness can wear out
The incredible relief patients feel when their skin clears is sometimes quickly deflated. Biologics sometimes stop working after several months or a year (or more). The efficacy of the drug often wears down gradually, but this process can also happen quite suddenly.
Experts arent certain whyand for whombiologics become ineffective. “This phenomenon is definitely known, but its not well studied,” says Craig Leonardi, MD, a clinical professor of dermatology at Saint Louis University who has participated in numerous clinical trials for biologics. “No company really wants to fund any research to explain why their drug stops working.”
The likely explanation is the makeup of the drugs, Dr. Leonardi says. Because biologics are made from natural proteins, the bodys immune system can reject the proteins when they are injected; it develops antibodies to the drug and clears the drug from your system before it has time to work.
If a biologic does stop working, dermatologists will often switch the patient to another biologic, which is often successful. Alternatively, dermatologists sometimes supplement a biologic with low doses of older systemic drugs, such as Soriatane or, most often, methotrexate. Although there has been no research done specifically in psoriasis patients to support this practice, studies conducted in the field of gastroenterology show that adding a low dose of methotrexate may prolong the effectiveness of biologics.
Once a drug stops working in any individual patient, however, its done for good. “If a patient develops an immunologic response, thats itthe drug is pretty much done,” says Dr. Leonardi.
There is hope, however, for patients who have come to the end of the line with biologics. Several new biologics currently in the pipeline for FDA approval could prove to be significant additions to the dermatologists arsenal.