What risk factors are associated with natalizumab (Tysabri) in the treatment of relapsing-remitting multiple sclerosis (MS) (RRMS), and how is its use restricted by the FDA?

Updated: Oct 08, 2019
  • Author: Christopher Luzzio, MD; Chief Editor: Jasvinder Chawla, MD, MBA  more...
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Natalizumab has been associated with progressive multifocal leukocephalopathy (PML), an opportunistic infection of the brain that can lead to death or severe disability. The risk of PML seems to increase with a history of previous immunosuppression, duration of exposure to natalizumab beyond 2 years, and JC virus antibody positivity.

Three cases of PML associated with natalizumab use prompted its temporary withdrawal from the market in 2005; however, it was reapproved in 2006 by the FDA for commercialization under a special restricted distribution program known as Tysabri Outreach Unified Commitment to Health (TOUCH). Use of natalizumab is limited to patients, physicians, and infusion centers that are registered with the TOUCH program.

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