Details
Tysabri increases the risk of progressive multifocal leukoencephalopathy (PML), a viral infection of the brain, which usually leads to death or severe disability. Health Canada has approved a product monograph change for Tysabri that identifies anti-JC virus (JCV) antibody status as a risk factor for developing PML. The change to the Health Canada label follows the U.S. Food and Drug Administration (FDA) and the European Commission approvals of anti-JCV antibody status as an additional factor to help clinicians identify people at risk for developing PML.
Infection with the JC virus (JCV) is necessary for the development of PML. The new label states that anti-JCV antibody negative status indicates that exposure to the JC virus has not been detected, while people who are anti-JCV antibody positive have a higher risk of developing PML. Individuals at highest risk of developing PML are those who:
- are anti-JCV antibody positive,
- have received prior immunosuppressant (IS) therapy and,
- have received treatment with TYSABRI for more than two years.
Signs of PML*:
Typical symptoms associated with PML progress quickly over days to weeks, and can include:
- personality or behavioral changes
- changes in thinking, memory, and orientation leading to confusion
- onset of seizures, clumsiness or progressive weakness on one side of the body
- disturbances of vision
In Canada, Tysabri is indicated as a monotherapy (not combined with other therapies). It is generally recommended for people with MS who have not responded adequately to other disease-modifying therapies or who are unable to tolerate them.
The most common serious side effects of Tysabri therapy are infections (including PML) and allergic reactions (rash, swelling, difficulty breathing). Treatment may also be associated with infusion-related reactions (headache, dizziness, fatigue, rash). Less common side effects include anemia, cough, muscle cramps and depression.
Healthcare professionals must monitor people on Tysabri for any new sign or symptom that may be suggestive of PML. Tysabri should be withheld immediately at the first sign or symptom suggestive of PML. Further information for persons with MS is available through the Canadian Tysabri Care Program at 1-888-827-2827.
*National MS Society(USA)