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    Dosing and


Significant reduction in the risk of increased physical disability sustained for 12 weeks1

The primary endpoint at 2 years was time to onset of sustained increase in disability, defined as an increase of ≥1.0 point on the EDSS from baseline EDSS ≥1.0 that was sustained for 12 weeks, or ≥1.5-point increase on the EDSS from baseline EDSS=0 that was sustained for 12 weeks.

Increase excluded disability confirmation within 30 days of a relapse.2

Potential Risk of TYSABRI and PML

  • TYSABRI increases the risk of progressive multifocal leukoencephalopathy (PML), an opportunistic viral infection of the brain that usually leads to death or severe disability
  • Cases of PML have been reported in patients taking TYSABRI who were recently or concomitantly treated with immunomodulators or immunosuppressants, as well as in patients receiving TYSABRI as monotherapy
  • Because of the risk of PML, TYSABRI is available only through a special restricted distribution program called the TOUCH® Prescribing Program
  • Healthcare professionals should monitor patients on TYSABRI for any new sign or symptom that may be suggestive of PML. TYSABRI dosing should be withheld immediately at the first sign or symptom suggestive of PML

Significant and powerful reduction in annualized relapse rate at 2 years

Results of AFFIRM (NAtalizumab Safety and EFFIcacy in Relapsing-Remitting MS), a 2-year, global, multicenter, double-blind, parallel-group trial that randomized 942 patients (in a 2:1 ratio) to receive either TYSABRI monotherapy (300 mg by intravenous infusion [n=627]) or placebo (n=315) every 4 weeks for up to 28 months (30 infusions).1

Significant reduction in Gd+ lesions at 2 years1

  • Changes in MRI findings often do not correlate with changes in the clinical status of patients (e.g., disability progression). The prognostic significance of these MRI findings has not been evaluated
  • 97% of TYSABRI patients were free of Gd+ lesions at 2 years vs 72% of placebo patients (p<0.001)
  • 57% of TYSABRI patients were free of new or enlarging T2 hyperintense lesions vs 15% of placebo patients (p<0.001)


  1. Polman CH, O'Connor PW, Havrdova E, et al; for the AFFIRM Investigators. A randomized, placebo–controlled trial of natalizumab for relapsing multiple sclerosis. N Engl J Med. 2006;354(9):899-910.
  2. Data on file, Biogen Idec.
TYSABRI® (natalizumab) is indicated as monotherapy for the treatment of patients with relapsing forms of multiple sclerosis. TYSABRI increases the risk of PML. When initiating and continuing treatment with TYSABRI, physicians should consider whether the expected benefit of TYSABRI is sufficient to offset this risk. See important information regarding the risk of PML with TYSABRI.

Please see full Prescribing Information, including Boxed Warning for Important Safety Information.

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Accepting outside referrals indicates an infusion site is willing to accept patients outside of their current practice. If they do not accept outside referrals then they only accept patients who are part of their current practice.


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