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Biogen, Genentech issue warning for Rituxan

Dec 19, 2006 | www.cbsmarketwatch.com

Biogen Idec and Genentech have issued a warning to healthcare providers for their oncology drug Rituxan, advising them that the drug has been linked to the deaths of two lupus patients from a rare brain disease.

According to an advisory sent out by the Food and Drug Administration early Tuesday, Biogen  and Genentech have sent a letter to healthcare providers informing them that two lupus patients taking Rituxan died of the rare brain disorder PML, an illness generally seen in patients with severely compromised immune systems.

Rituxan, which is used to treat non-Hodgkin's lymphoma and rheumatoid arthritis, is not approved to treat lupus. However, such drugs are sometimes prescribed to treat conditions other than those they are approved for, a practice known in the medical industry as "off-label" use. Off-label prescribing is often done for patients who are not responding well to more standard therapies.

"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, in a statement Tuesday.

"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," Galson added.

Based on the antibody rituximab, Rituxan works by manipulating the immune system and belongs to a class of drugs known as immunomodulators. The drug has been on the market since 1997.

This is the second time that Rituxan has been linked to PML, a condition generally seen in patients with advanced AIDS. In February of this year, the drug's label was changed to advise physicians that cases of PML had been observed in patients taking Rituxan for lymphoma. A majority of the patients affected had also taken other immunomodulators, according to the FDA.

The agency also noted that PML has been seen in lupus patients who had taken immunomodulator drugs other than Rituxan.
Rituxan, which had 2005 sales of $1.8 billion, was developed by Genentech and Idec, a predecessor of Biogen Idec. The drug is Biogen's biggest revenue driver next to its popular multiple sclerosis therapy Avonex.

In early 2005, Biogen was hit hard when it discovered that its newly-launched multiple sclerosis drug, Tysabri, had been linked with three cases of PML. Like Rituxan, Tysabri is also an immunomodulator. In the three PML cases associated with Tysabri, the patients were found to have also taken other immunomodulators, such as Biogen's Avonex.

Tysabri was put back on the back earlier this year, with a warning against using the drug with other immunomodulator drugs.