Efalizumab (brand name Raptiva, pronounced rap-TEE-va) is a systemic biologic therapy manufactured by Genentech and Xoma. The companies filed in December 2002 with the U.S. Food and Drug Administration (FDA) for approval for the treatment of moderate to severe psoriasis. It could be approved as early as October 2003.

How does it work?

In psoriasis and psoriatic arthritis, certain immune system cells are triggered and become overactive. The cells set off a series of events in the body, eventually causing psoriasis to develop on the skin and arthritis symptoms to develop in the joints.

Raptiva is an antibody that prevents certain activated immune cells, called "T cells," from entering tissues such as the skin. T cells are a type of white blood cell in the body; in psoriasis, once T cells are mistakenly activated, they can trigger other immune responses and fuel the development of psoriasis lesions.

Raptiva is given by subcutaneous (under the skin) injection once a week. It can be done at home by patients themselves. Once it is stopped the symptoms of the disease eventually return. Raptiva must be taken to maintain improvement.

What are the possible side effects?

In clinical trials, patients experienced mild to moderate flu-lie symptoms in the first few doses, but the rate of these dropped to normal levels after the third dose. Patients have been studied for up to one year.

• Mild to moderate headache
• Pain
• Chills
• Upset stomach
• Fever

Raptiva does inhibit the immune system to a degree. Long-term side effects are not yet known. Safety in combination with other psoriasis therapies has not been assessed.