Dec. 19, 2006 -- The FDA has issued a public health advisory on Rituxan after two lupus patients taking the drug reportedly died of a viral brain infection.

Both patients developed progressive multifocal leukoencephalopathy (PML), a brain infection caused by a common but usually harmless virus. However, in those who contract PML, the infection is usually fatal; there are no effective treatments.

Rituxan is a powerful drug used to suppress the immune system. It works by blocking the effect of specific immune cells in the blood, known as B cells, for up to nine months.

The drug is approved for use only in patients with certain types of cancer, called non-Hodgkin's lymphoma, and for rheumatoid arthritis when other treatments have failed. Rituxan is not approved to treat lupus.

However, Rituxan's maker, Genentech, estimates that approximately 10,000 lupus patients have been treated with Rituxan, according to the FDA. Genentech is a WebMD sponsor.

The FDA is working to gather more information about Rituxan and PML, and to strengthen the drug's warnings about PML.

Signs of PML

Patients treated with Rituxan should contact their doctor if they experience any warning sign of PML, says the FDA.

Signs of the disease include confusion, dizziness or loss of balance, difficulty talking or walking, and vision problems.

These symptoms are also associated with the underlying diseases for which Rituxan may be prescribed, making it harder to spot PML, the FDA notes.

The FDA advises doctors considering treating a patient with Rituxan to inform that patient about the chance of developing PML.

Patients taking or considering taking Rituxan should be aware of the chance of developing PML and ought to discuss it with their doctor, the FDA adds.

Rituxan's labeling was updated in February 2006 to include information about reports of several different types of viral infections, including PML, that had become active again or worsened in cancer patients taking the drug.

SOURCE: FDA: "Public Health Advisory: Rituximab (marketed at Rituxan)."