The California-based firm Genentech is withdrawing its psoriasis drug Raptiva from the market because of reports of three confirmed, and one suspected, cases of progressive multifocal leukoenephalopthy (PML), a rare and usually fatal brain disease, in patients who had been taking Raptiva. All four patients had been treated continuously for at least three years.

Immune system suppression

Raptiva was approved by the Food and Drug Administration to treat psoriasis in 2003. Psoriasis is a chronic non-contagious autoimmune disease which causes joint pain and excess skin production. Genentech estimates that 20,000 people in the United States and approximately 46,000 people worldwide have been treated with the drug.

By suppressing T-cells, which are part of the immune system, to combat psoriasis, Raptiva also weakens the ability of the immune system to fight infections, including bacterial sepsis, viral meningitis, invasive fugal disease and the virus that causes PML.

PML is a rare, progressive, and potentially deadly brain infection caused by a common virus, Polomavirus JC, which can infect the central nervous system of individuals with a compromised immune system. With this disease, the virus gradually destroys the myelin sheath that protects nerve cells, impairing nerve signal transmission throughout the body

No known treatment or cure

There is no way to predict in advance who will develop PML, and there is no known effective treatment or cure. The disease is almost always fatal, and those who do live with PML are severely disabled.

All three patients, and the one suspected case, who developed PML had been taking Raptiva for at least three years. The drug is given by injection once a week. None had been taking other drugs known to suppress the immune system.

Genentech is withdrawing the drug gradually to give doctors and patients time to find alternative treatments, warning that abrupt withdrawal could worsen psoriasis and lead to hospitalization. No new prescriptions will be filled and existing prescriptions will be refilled until June 8. After that date, Raptiva will no longer be available.

Signs and symptoms of PML include confusion, dizziness, loss of balance, difficulty talking or walking, vision problems, Patients taking Raptiva who develop any of these problems should immediately contact a physician.

Patients or family members who notice any sudden changes or signs of PML should also contact an attorney. A recent Supreme Court ruling, Wyeth V. Levine, which held that a patient injured by a drug can sue the company even though the FDA has overseen and approved warnings on drug labels, opens the door for plaintiff suits.