Genentech and Biogen Idec have notified healthcare professionals that a patient with rheumatoid arthritis who took the firms’ blockbuster Rituxan has died after developing the rare brain disease progressive multifocal leukoencephalopathy.

In a posting on the US Food and Drug Administration’s website, Genentech and Biogen noted that this is the first reported case of PML in a Rituxan (rituximab)-treated patient with RA. Specifically, the case of John Cunningham (JC) virus infection with resultant PML and death was reported in the patient who was diagnosed approximately 18 months after the last dose of Rituxan.

The firms noted that this case was confounded by the patient’s development of oropharyngeal cancer, which was treated with chemotherapy and radiation therapy nine months prior to the development of PML. The patient had longstanding RA treated with immunosuppressants and “a complex medical and rheumatologic history including Sjogren’s syndrome and undetectable complement C4 levels”, they added.

The labelling on Rituxan has been updated to reflect the new case, having previously included reports of PML in patients taking the drug for off-label uses, including lupus.

The case comes just a fortnight after Biogen and partner Elan Corp after the firms reported two new cases of PML in Europe in patients with multiple sclerosis taking Tysabri (natalizumab) as monotherapy. These were the first cases of PML that have been reported following the drug’s re-appearance on the market in June 2006.