European Pharmacovigilance Risk Assessment Committee (PRAC) update recommendations to minimise the risk of the rare brain infection with natalizumab

Following a review of the risk of progressive multifocal leukoencephalopathy (PML) with natalizumab PRAC concluded that for patients at higher risk of PML more frequent MRI scans (e.g. every 3 to 6 months) should be considered.

PML is a rare and very serious brain infection caused by John Cunningham (JC) virus.  Known risk factors for the development of PML in patients treated with natalizumab are the presence of antibodies against JC virus, treatment for more than two years, and use of immunosuppressant medicines before starting natalizumab therapy. Patients who have all three risk factors are considered at higher risk of PML.  New data from clinical studies suggest that, in patients who have not been treated with immunosuppressants before starting natalizumab, the level of JC antibodies (index) relates to the level of risk for PML.  PRAC concluded therefore that patients with a high antibody index who have not used immunosuppressants before natalizumab and have been treated with natalizumab for more than 2 years are also considered at higher risk of PML.

 

In patients at higher risk of developing PML, treatment with should only be continued if benefits outweigh the risks.  If PML is suspected at any time, treatment with natalizumab must be stopped until PML has been excluded.