Changes to Tysabri’s Labeling

Two changes have recently been made to the labeling and prescribing information for Tysabri® (natalizumab). Manufactured and marketed by Biogen Idec and Elan, Tysabri is approved by the United States Food and Drug Administration (FDA) for the treatment of multiple sclerosis (MS) as well as Crohn’s disease.

The first change may help individuals to be approved sooner by their health insurance company for Tysabri, after failing to respond adequately to (or not able to tolerate) another single disease-modifying therapy for MS. Previously, the prescribing information referred to an inadequate response to "alternate therapies," which is more than one and could be interpreted as needing to try several, and possibly all other MS therapies, before Tysabri could be approved. The new copy states, "Tysabri is generally recommended for patients who have had an inadequate response to, or are unable to tolerate, an alternate MS therapy." This new wording means that once an individual has tried one of the other five MS long-term treatments without success, he or she falls under the general recommendation for treatment with Tysabri, if deemed appropriate by one’s physician.

The second change is in response to the two newly discovered cases of progressive multifocal leukoencephalopathy (PML), in patients taking Tysabri as a monotherapy (in conjunction with no other disease-modifying therapy) for the long-term treatment of MS. PML is an often-fatal viral infection of the brain. The following sentence has been added to Tysabri’s labeling and prescribing information: "In the postmarketing setting, additional cases of PML have been reported in multiple sclerosis patients who were receiving no concomitant immunomodulatory therapy." The fact that PML occurred in two patients taking Tysabri alone also prompted the revised wording in the "black box" warning. It now states, "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."

As an additional note to readers, regarding the two patients who recently developed PML, one had never taken a disease-modifying therapy prior to Tysabri, and the second patient had been given immunomodulating drugs in the past. However, neither patient was taking Tysabri in conjunction with any other disease-modifying therapy. These two cases were reported to the FDA on July 31, 2008.

For more information on these two new cases of PML, please refer to MSAA’s August 5, 2008 update on this website. For general information on Tysabri and complete prescribing information, please visit

Information summarized by Susan Wells Courtney, MSAA Senior Writer and Creative Director
Reviewed by Dr. Jack Burks, MSAA Chief Medical Officer

Media inquires should be addressed to Amanda Bednar, MSAA Public Relations Manager, at (800) 532-7667, extension 122 or via email: