In a notice posted on its website, the FDA said Rituxan was approved to treat lymphoma (cancer of the lymph nodes) and rheumatoid arthritis, but not lupus. However, doctors sometimes prescribe the drug to treat lupus through a practice known as "off-label" prescribing -- in which doctors can prescribe a medication to treat a condition it was not approved for, as long as the medicine was approved by the FDA to treat any other condition.
The two patients died after contracting a rare brain infection -- progressive multifocal leukoencephalopathy (PML) -- after they took Rituxan. The prescription instructions for Rituxan already include warning information on viral infections -- including PML -- associated with taking the drug. Cancer patients taking Rituxan have reported worsening of existing viral infections after taking the drug, or reactivation of old infections.
According to the FDA, there is no known treatment for PML, and doctors should discuss the risk of taking Rituxan with patients. "FDA is working to gather more information about Rituxan and PML and to strengthen the warnings about PML in the Rituxan product label," the agency said.
Biogen and Genentech said letters had been issued to doctors warning of the drug's possible effects on lupus patients. Debra Charlesworth, spokeswoman for Genentech, said the company was conducting clinical trials of Rituxan for treating lupus.
Consumer health advocate Mike Adams said the patients' deaths highlight the consequences of the FDA's allowance of rampant off-label prescribing.
"The fact that any FDA-approved drug can be legally prescribed for literally any health condition whatsoever -- including those for which it has never been tested -- makes a mockery of the so-called scientific medicine systems operating today," Adams said.
"It is beyond explanation that a perfectly safe herb cannot be legally prescribed for any condition, yet a dangerous drug can be legally prescribed for every condition. This is not a system of medicine; it is a system of pro-pharmaceutical dogma in which patients' lives are put at risk by overzealous marketing and prescribing of drugs," he said.