About one-third of multiple sclerosis patients testing negative for antibodies against the JC virus -- suggesting that natalizumab (Tysabri) would be relatively safe -- were found to have active viremia, researchers said.
The report, published in the June 6 issue of the New England Journal of Medicine,
raises the specter that patients with negative JC serology results
could be given natalizumab when they may actually be at high risk for
progressive multifocal leukoencephalopathy (PML), an often fatal type of
brain inflammation. click for full article
