All four had been treated with Raptiva for more than three years. None was taking other treatments that suppress the immune system.
The FDA is reviewing the reports of PML in Raptiva users and says it will take appropriate steps to ensure that Raptiva's risks do not outweigh its benefits, that patients prescribed Raptiva are clearly informed of PML's signs and symptoms, and that health care professionals carefully monitor patients on Raptiva and those who have discontinued the drug for any signs of PML.
PML is caused by a virus that affects the central nervous system. PML usually occurs in people whose immune systems have been severely weakened. It leads to an irreversible decline in neurologic function and death.
PML symptoms may include unusual weakness, loss of coordination, changes in vision, difficulty speaking, and personality changes.
Raptiva is a once-weekly injection for adults with moderate to severe plaque psoriasis who are candidates for systemic (whole body) therapy or phototherapy. Raptiva suppresses T-cells, which are part of the immune system, to curb psoriasis. Suppressing T-cells increases a patient's susceptibility to infections.
In October 2008, Raptiva's label got a "black box" warning -- the FDA's sternest warning -- about the risk of life-threatening infections, including PML.
Raptiva is made by Genentech. In an email to WebMD, Genentech spokeswoman Tara Cooper says, "We take the risk of PML very seriously and are working diligently with the FDA to put the right plans in place that will help protect patient safety. We are evaluating all possible approaches to address the risk of PML with Raptiva use, including a risk minimization plan. It is premature to disclose the scope of our plans until we've reached a formal agreement on those plans with the FDA."