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Psoriasis Drugs Strike Immune Targets

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Nov. 20, 2003 -- Psoriasis is a common skin disease that cannot be cured but can be treated. There are a growing number of options for the treatment of psoriasis. Among them are two drugs called Raptiva (efalizumab) and Enbrel (etanercept). Reports of the efficacy of these two drugs appear today along with an editorial in The New England Journal of Medicine.

Psoriasis is an autoimmune disease. The immune system attacks the skin and causes new skin cell growth to be too rapid. This produces thick, red, scaly, inflamed patches on the skin. Psoriasis affects about 4.5 million Americans. Plaque psoriasis, the most common form of the disease, is characterized by inflamed patches of skin topped with silvery white scales. Psoriasis can be limited to a few spots or involve extensive areas of the body, appearing most commonly on the scalp, knees, elbows and trunk.

Raptiva (efalizumab)

This drug was approved late last month by the FDA for the treatment of moderate-to-severe plaque psoriasis. Raptiva is a form of biologic therapy. It is a humanized monoclonal antibody that inhibits the activation of T cells which are responsible for the symptoms of psoriasis. The drug can be self-administered by patients as a single, once-weekly, subcutaneous injection.

What's New: A randomized trial has shown the efficacy of Raptiva as a treatment for moderate-to-severe plaque psoriasis. After 12 weeks, 25% of the patients who received Raptiva had an improvement in a psoriasis index of at least 75%, as compared with 5% of those who received placebo.

Comment: Studies of longer duration are needed to determine whether Raptiva is a useful therapy for psoriasis.

Enbrel (etanercept)

This is also a form of biologic therapy. Enbrel is an injectable drug approved by the FDA for treating psoriatic arthritis, ankylosing spondylitis, and rheumatoid arthritis. Enbrel blocks what is called tumor necrosis factor (TNF) alpha, a protein that the body makes. TNF alpha promotes inflammation and its associated fever and signs (pain, tenderness, and swelling). Enbrel binds to TNF alpha and acts like a sponge to remove most of the TNF alpha molecules from the blood.

What's New: Treatment with Enbrel resulted in significant improvement for patients with moderate-to-severe plaque psoriasis who participated in a 24-week randomized trial The rates of adverse events were similar in the Enbrel and placebo groups.

Comment: Enbrel is an effective treatment for plaque psoriasis. However, the safety and efficacy of the long-term use of this drug for psoriasis have not yet been studied.

Perspective

Which of these drugs is better? That is uncertain. But "one thing is certain: we have not seen the last of biologic therapies for psoriasis," concludes Thomas S. Kupper in today's New England Journal, "and this will ultimately be a boon to patients with this chronic, debilitating disease."

Sources:

Mark Lebwohl and Others. A Novel Targeted T-Cell Modulator, Efalizumab, for Plaque Psoriasis. New Engl J Med 2003; 349: 2004-2013. Craig. L. Leonardi and Others. Etanercept as Monotherapy in Patients with Psoriasis. New Engl J Med 2003; 349: 2014-2022. Thomas S. Kupper. Immunological Targets in Psoriasis. New Engl J Med 2003; 349: 1987-1990.

For more in-depth information, please see the following areas:

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• Psoriasis
• Psoriasis, Lupus, RA, Share One Gene
• etanercept (Enbrel)

Related Centers:

• Psoriasis Center
• Focus Topic On Skin, edited by Alan Rockoff, MD, FAAD, Tufts University School of Medicine, Boston
• Focus Topic on Arthritic Conditions, edited by William C. Shiel, Jr., MD, FACP, FACR, Rheumatology Specialist and Chief Medical Editor, MedicineNet.com