"Rituxan is used in both approved and off-label settings, and therefore it is very important for prescribers as well as patients to be aware of these new reports of the risk of PML," said Dr. Steven Galson, director of FDA's Center for Drug Evaluation and Research. "Patients who are being treated or have been treated with Rituxan who experience any major changes in vision, balance, or coordination, or who experience confusion, should promptly call their doctor."
Rituxan, which has been marketed since 1997, acts on the body's immune system by decreasing certain types of white blood cells. This makes the drug effective in treating lymphoma and rheumatoid arthritis, but it also increases the body's susceptibility to infection. The Rituxan label was updated in February 2006 to include postmarketing reports of cases of serious viral illnesses, including PML, in patients with lymphoma who received Rituxan. There have been 23 confirmed cases of PML in patients with lymphoid malignancies either during or after completion of treatment with Rituxan. The majority of these patients also had received other drugs known to affect the immune system.