Rituxan, Arthritis and cancer drug by Genentech, Inc. as well as by Biogen Idec, Inc. is under scanner. The Food and Drug Administration (FDA) reported a case of a deadly brain infection’ progressive multifocal leukoencephalopathy (PML) in a patient who was prescribed the drug.

Rituxan, known generically as rituximab  was approved to treat non-Hodgkin’s lymphoma in 1997 and rheumatoid arthritis in 2006.

According to the FDA, this is the first report of the infection in an individual undergoing treatment for arthritis, though cases of PML have previously been reported in patients taking Rituxan for unapproved uses, including lupus. However, Genentech spokeswoman Tara Cooper said that the drug’s label does mention the risks of the infection. She said, “The patient had a number of confounding factors that make it difficult to assess the potential role, if any, that Rituxan exposure may have played.”

FDA has cautioned doctors against prescribibg Rituxan with immediate effect, for patients who develop the infection termed as progressive multifocal leukoencephalopathy or PML. It urged doctors treating rheumatoid arthritis to watch for neurological problems in patients taking Rituxan.