FDA issues PML warning for Rituxan

The US Food and Drug Administration is alerting health care professionals and patients treated with Rituxan (rituximab) to reports of a serious side effect risk in those using or who have used the drug. The agency recently learned that two systemic lupus erythematosus (SLE) patients on Rituxan, which is co-marketed by US drug firms Genentech and Biogen Idec, developed progressive multifocal leukoencephalopathy (PML), a fatal viral infection of the central nervous system. This side effect has been reported in patients as late as 12 months after their last dose.

Rituxan, which earned $1.8 billion in 2005, has been marketed since 1997 and 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. In after-market activity, on the day of the FDA warning, December 18, shares in Genetech fell 1.2% to $79.97, while Biogen Idec lost 2.2% to close at $1.13.

SLE is not an approved indication for Rituxan, which is cleared only for the treatment of patients with non-Hodgkin's lymphoma and those with rheumatoid arthritis whose disease no longer responds to other common treatments. "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 Steven Galson, director of the 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," he said.