Third patient taking arthritis drug develops PML

ROCKVILLE, Md. A third case of a deadly brain infection has occurred in a patient using a drug to treat arthritis, the drug’s manufacturer and the Food and Drug Administration have advised healthcare professionals.

The FDA and Genentech said a third case of progressive multifocal leukoencephalopathy, also known as PML, had occurred in a patient using the drug Rituxan (rituximab) to treat rheumatoid arthritis.

Last week, the agency declined to approve a treatment involving the combination of Rituxan with methotrexate in patients who no longer responded to disease-modifying drugs alone – including methotrexate – also citing the risk of PML infection, even though PML is rare in patients using the drug.

PML results from infection by the JC virus, which is present in most adults but kept in check by the immune system. Full-blown AIDS and use of immunosuppressant drugs can give the virus the opportunity to replicate, resulting in a deterioration of brain function and, in most cases, death.

Genentech voluntarily withdrew another immunosuppressant drug, the psoriasis treatment Raptiva (efalizumab), earlier this year after determining that the risk of PML in patients did not outweigh the drug’s benefits.