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Remicade® (Infliximab) as a Treatment for Psoriasis
Psoriasis is a non-contagious, lifetime, auto-immune disease afflicting roughly 5.5 million people (1-3% of the population) in the United States. People with psoriasis develop raised, red patches on their skin – most commonly around the scalp, knees, elbows and torso. These patches are often covered with white, flaky dead skin cells. There are several different types of psoriasis such as plaque (the most common), guttate, pustular, inverse, and erythrodermic as well as other diseases associated with psoriasis such as psoriatic arthritis and Crohn’s disease. Currently there is no cure for psoriasis; however treatments ranging from topical rubs to UVA and UVB light to intravenous medications (like Remicade®) are available. (www.psoriasis.org)
Psoriasis: An Auto-Immune Disorder
The cause of psoriasis is not yet understood. There is a belief that psoriasis is partly hereditary. Yet, many doctors agree that psoriasis is an auto-immune disorder. When the immune system is functioning regularly, white blood cells and antibodies distinguish self from non-self, and use different mechanisms to destroy outside agents. However, in patients with psoriasis the immune system malfunctions and mistakes normal skin cells for outside agents. This triggers a cascade of events that leads to the body destroying its own skin. (http://dermatology.about.com/od/psoriasisbasics/a/psorcause.htm) Furthermore, the immune system also speeds up cell growth. Normally, skin cells are replaced every 28-30 days as the cells on the surface of the skin are sloughed off. But in patients with psoriasis new skin cells are made every 3-4 days – which accounts for the build up of excess skin cells leading to the raised, red patches indicative of the disease. (www.psoriasis.org) The malfunctioning mechanism in the immune response has been identified as tumor necrosis factor-α (TNFα). TNFα has been seen in higher levels than normal in psoriatic lesions on the skin. It is a cytokine, a type of signaling compound used by the immune system, which binds to antigens on skin cells in psoriatic patients and triggers an immune response. (Gottlieb)
What is Remicade® (Infliximab) and how does it Work?
Infliximab was developed to inhibit the signaling effects of TNFα. Infliximab is an anti-TNFα monoclonal antibody. Drs. Tan, Gordon, Lebwohl, and George describe Infliximab as a “a novel chimeric anti–tumor necrosis factor (anti–TNF-) monoclonal antibody composed of constant regions of the human IgG1 spliced to the murine [rodent] variable antigen-binding region of a high-affinity human anti–TNF- antibody.” (Tan) This means that certain RNA factors are taken from rodents and transplanted into a human constant region that then codes for the antibody Infliximab which effectively binds to TNFα and blocks its effects in the immune system. It is this variable section of the anti-body (coded for by the variable murine RNA in the plasmid vector) that recognizes the TNFα as “non-self” and binds to it, thereby incapacitating it and keeping it from activating the TNFα specific white blood cells from destroying normal dermal cells that do not need to be removed.
Infliximab is administered through intravenous infusion. The infusion takes 2-3 hours yet the effects can last for weeks, and improvements in psoriasis can be seen for months with regular infusions. Like all medications Infliximab must be monitored for possible side effects such as hypotension and allergic reactions during the infusion process and infection after-the-fact due to the immunosuppressive qualities of the drug. Many cases in which people became infected, the patient was also taking various other medications for psoriasis or transplantations that suppressed the ability of his or her immune system to function properly. (Lebwohl)
Research into the Viability and Safety of Infliximab as a Treatment for Psoriasis
Much research has been done to determine the effectiveness of Infliximab as a treatment for psoriasis, and to see for which patients and which types of psoriasis the medication benefits most. Many researchers want to see the effects of Infliximab on psoriatic patients who have had little success with other drugs or treatments.
One such study was jointly carried out by researchers in Pennsylvania, New Jersey, and Texas from 2001-2003. This double-blinded look at the effects of the medication using various dosages (3 mg/kg, 5 mg/kg) or a placebo aimed to understand how patients using only Infliximab responded after several cycles of the drug. These patients were not allowed to use any other form of treatment, must be at least 18 years of age and have a plaque form of psoriasis over at least 10% of their body. The results were convincing:
The evidence clearly showed the investigators that the patients taking the medication (of either dosage) showed remarkably more improvement than those subjects taking the placebo. The most telling statistic is the fact that over 50% of those taking Infliximab showed at least a 90% improvement. The above figure clearly shows the effect of Infliximab as a treatment for psoriasis.
However, when using experimental drugs it is also necessary to assess the risks involved. These same researchers showed that the patients treated with Infliximab vs. the placebo did have slightly more adverse events (79% of patients with Infliximab vs. 63% taking a placebo). But the difference between the two is small enough to rule out any major harmful effects of the drug and be seen as merely a normal difference for people on a drug versus those not taking it. (Gottlieb)
Other such studies have been carried out in very similar manner with comparable results. In 2000 and 2001 researchers also using the double-blind format, in order to ensure validity of the data, showed 82% of patients taking 5 mg/kg and 91% of patients taking 10 mg/kg showed notable changes in the severity of their psoriasis and also scored better on the doctors’ assessments of other health factors related to psoriasis. This compared to the only 18% seeing similar such results while taking only a placebo led the doctors to believe in the treatment efficacy of the Infliximab as a suitable treatment for psoriasis and other psoriatic related disorders. (Lebwohl)
There is much more literature with very similar results. One such experiment was carried out by Dr. Gottlieb, a clinical researcher in New Jersey, who published a paper in 2003 showing again that the effects of Infliximab on psoriasis are obvious. However, his results were a little lower than some of the other studies (with only 82% of 5 mg/kg patients and 73% of 10 mg/kg patients seeing improvement of at least 75% in his assessment compared to 18% of those taking a placebo). Despite the lower success rate in this study it is still very clear that Infliximab creates a remarkably better chance for success than no treatment. (Gottlieb – “Infliximab for Psoriasis”) This leads to the belief by doctors that further research into more long-term effects of Infliximab as a primary treatment for psoriasis or in coordination with other treatments in warranted and necessary.
For many people the idea of taking a genetically altered medication is troubling. However, alternative methods such as recombinant DNA drugs, like Remicade®, have proven to be extremely effective and in some cases have the ability to be more beneficial to the patient than standard medical care. The data supporting the use of Remicade® as a treatment for psoriasis and other related diseases such as psoriatic arthritis and Chrohn’s disease is overwhelming. The percent of patients improving more than 50% while on the medication speaks volumes for the efficacy of this drug. Due to the remarkable ability of Remicade® to ease the symptoms of psoriasis, it is only logical to expect to see an increase in the prescription of this drug and its role as a treatment of psoriasis become commonplace.
3. Gottlieb, Alice B. MD, PhD, Robert Evans PharmD, Shu Li MS, Lisa T. Dooley DrPH, Cynthia A. Guzzo MD, Daniel Baker MD, Mohan Bala PhD, Colleen W. Morono PhD, and Alan Menter MD. Infliximab induction therapy for patients with severe plaque-type psoriasis: A randomized, double-blind, placebo-controlled trial, Journal of the American Academy of Dermatology, Volume 51, Issue 4, October 2004, Mosby Inc. Pp. 534-542
4. Lebwohl, Mark MD. Psoriasis, The Lancet, Volume 361, Issue 9364, April 2003, Elsvier. Pp. 1197-1204.
5. Tan, Mei-Heng MD, Marsha Gordon MD, Oscar Lebwohl MD, James George MD, and Mark Lebwohl MD. Improvement of Pyoderma Gangrenosum and Psoriasis Associated With Crohn Disease With Anti–Tumor Necrosis Factor α Monoclonal Antibody. Archives of Dermatology, Volume 137, Issue 7, July 2001. American Medical Association, Pp. 930-933.
6. Gottlieb, Alice B. MD, PhD. Infliximab for Psoriasis. Journal of the American Academy of Dermatology, Volume 49, Issue 2, Supplement 1, August 2003, Mosby Inc. Pp. 112-117.
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