"I would encourage anyone who has given up on his treatment to see his dermatologist to discuss the idea of using a biologic to treat psoriasis."(BRUCE BEBO,PHD)
Bruce Bebo, PhD, is the director of research and medical programs for the National Psoriasis Foundation.
Q: What are biologic drugs and how do they treat psoriasis?
A: The definition of a biologic is a medicine that is derived from a living organism. They are generally large molecules, compared to other drugs, such as aspirin, which are small. And biologics are most often proteins. They must be administered by injection under the skin, into the veins or muscles, because the enzymes and acid in the digestive tract would destroy them if they were taken orally.
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Q: How often do they have to be injected?
A: They all have different frequencies, ranging from once every few days to once every few weeks. Many patients find self-injection convenient, but others prefer to have a doctor or nurse perform the injections. Many, if not all, of the pharmaceutical companies that make biologics will provide in-home training for self-injection.
Q: How have these drugs changed the treatment of psoriasis?
A: There are a lot of people who are not treating their psoriasis at all—about 40%. My feeling is that some people have given up, because in the past the treatments have been inconvenient and modestly effective. In most cases, the biologics are more effective and convenient. So I would encourage anyone who has given up on his treatment to see his dermatologist to discuss the idea of using a biologic to treat psoriasis.
Next Page: How biologics work
[ pagebreak ] Q: How do biologics work?
A: There are three categories of biologics. One category is the anti–T cell agents; it includes Amevive (alefacept) and Raptiva (efalizumab), which inhibit the activity of a specific type of white blood cell called a T cell. Psoriasis occurs when T cells inappropriately produce inflammatory factors in the skin that cause the overproduction of skin cells and the pain and itching that characterize psoriasis plaques. While we don't know precisely why the T cells become inappropriately activated, it's most likely a combination of genetic predisposition to psoriasis coupled with exposure to some type of environmental trigger. Drugs that stop the activity of T cells reduce the inflammatory response in the skin.
The second class of biologics are molecules that neutralize the inflammatory factor TNF (tumor necrosis factor). TNF, which is made by T cells and other immune cells, can trigger the inappropriate proliferation of skin cells and amplify the immune response in the skin, a process that can lead to psoriasis. Drugs in this category—including Remicade (infliximab), Humira (adalimumab), and Enbrel (etanercept)—slow down and, in some cases, stop the inflammatory process responsible for psoriasis.
The newest category of biologics blocks two types of interleukin (IL), additional immune factors involved in psoriasis—IL-12 and IL-23. These factors are produced by another important type of immune cell—dendritic cells. Normally these cells are important in helping to fight infections. In psoriasis, dendritic cells produce inflammatory factors, including IL-12 and IL-23, that act on skin cells and other immune cells such as T cells. A new drug called ustekinumab is an IL-12/-23 blocker that has recently been found in clinical studies to dramatically suppress the development of psoriasis. Based on these studies, it was recently approved by an FDA advisory committee for the treatment of psoriasis and will probably get FDA approval by the end of the year. Another IL-12/-23 blocker called ABT-874 is in phase 3 clinical studies and also looks promising for the treatment of psoriasis.
Q: How important are biologics in the treatment of psoriasis?
A: Any additional therapy to the arsenal of drugs used to treat psoriasis is a real benefit. The problem in psoriasis is that treatments that work for people tend to work for a period of time and then stop working—so the more treatments you have, the more tools you have to fight the disease and the better off you are. Biologics can more specifically target certain aspects of the immune system, which—at least in theory—should result in fewer side effects than other, more general, immunosuppressive drugs.
Next Page: What are the risks?
[ pagebreak ] Q: What are the general side effects?
A: Swelling and redness around the injection site is the most common side effect, but it usually subsides over time.
Q: What are the safety concerns?
A: The primary concerns for safety are an increased risk for infection and possibly cancer, particularly lymphomas. Both of these risks are likely related to the immune-suppressing nature of this drug family. The risks for infection can often be mitigated by being vaccinated for the flu and other common preventable infectious diseases, avoiding exposure to infectious agents, and being in good general health. While the risk for cancer is statistically significant, the risk associated with treatment is still pretty low. It is also important to note that these risks are also not unique to the biologic class. In either case, patients should discuss the potential risks and benefits with their doctor in order to determine the most appropriate course of treatment.
Q: When should someone consider a biologic?
A: One should consider the impact the disease has on his quality of life. Another issue is access. These medications are expensive and many insurance providers have rules regarding coverage that include how much of your body's surface area is affected. There are also other treatments for psoriasis, such as creams, light therapy, or other systemic agents that can also be useful. You have to make that decision with your physician, but generally a person with moderate to severe psoriasis is someone who should consider taking a biologic.
If your disease is not being controlled by the traditional systemic medicines, then considering a biologic is probably a smart thing to do.
Q: Does the doctor you choose matter?
A: You really should seek out a dermatologist or rheumatologist (if you have psoriatic arthritis) who has experience prescribing biologics.
Next Page: Biologics and psoriatic arthritis
[ pagebreak ] Q: Do these drugs treat psoriatic arthritis?
A: The TNF inhibitors—Remicade, Humira, and Enbrel—work for psoriatic arthritis.
Q: Are there any patients who should definitely not take biologics?
A: Your doctor should determine whether taking a biologic is appropriate. Each of these medications has specific contraindications in their prescribing information. But certainly, if you are being treated for an infection or have signs of an infection, it is better to wait until the infection has cleared before starting treatment. People with diabetes or other immune system problems or people taking another immunosuppressant medication are not good candidates for treatment with a biologic. Since the effects of these drugs on pregnancy havent been well studied, they should probably be avoided by pregnant women, except under very special circumstances.
Q: How do you choose which class to use?
A: The TNF blockers are often the physician's first thought when it comes to biologics. There are a lot of reasons for this, but the fact that they are quite effective and have a reasonably long safety record is the most likely reason why this class is chosen more often than the others. However, there are times when a T-cell blocker is preferred, like when a person doesnt respond to a TNF blocker or has a special type of psoriasis, such as psoriasis of the palms and soles of the feet. The IL-12/23 blocking drug is not available to the public yet, but when it is approved by the FDA, it is likely to be an important additional tool to fight psoriasis. Someday in the not too distant future, we will be able to use a blood test to tell which of the available treatments is likely to work best—instead of relying so much on trial and error.
Q: How have biologics changed the treatment of psoriasis?
A: The potent effect of the biologic class of medicines has really increased our expectations regarding new treatments. The bar has definitely been raised, and with this in mind, I expect that more effective and convenient treatments will be coming out in the near future.