CLEVELAND, Feb. 2 -- Plasmapheresis can rapidly clear natalizumab (Tysabri) from circulation, potentially offering a way to mitigate progressive multifocal leukoencephalopathy (PML), the rare, often-fatal condition triggered by the drug, researchers here said.
In clinical trials, about 0.1% of patients treated with natalizumab -- approved for multiple sclerosis and Crohn's disease -- developed PML. The condition is apparently triggered by the drug's reactivation of latent infection by the JC virus.
Three sessions with a plasmapheresis technology accelerated natalizumab clearance by three-fold in 12 patients with multiple sclerosis, reported Robert J. Fox, M.D., of the Cleveland Clinic, and colleagues in the Feb. 3 issue of Neurology.
"The results of this study suggest that plasma exchange may be effective in rapidly restoring central nervous system immune effector responses in natalizumab-treated patients, which may benefit patients with serious opportunistic infections such as PML," they wrote.
Without plasmapheresis, this level of natalizumab clearance would take 97 days after drug infusion with a normal dose.