Tysabri (natalizumab) is an antibody treatment given in the vein (I.V.) every 4 weeks. Tysabri blocks lymphocytes, a type of white blood cell, from crossing the blood vessel wall to enter the brain or spinal cord. In clinical trial, Tysabri prevented 68% of relapses, reduced new T2-hypertense MRI activity by 83%, reduced new active contrast-enhancing lesions by 92% and slowed the likelihood of progression of disability by 42%. Based on an MRI scan at 2 years, 97% of patients were free of active contrast-enhanced lesions.

Risks include severe allergic infections and serious infections. A rare and untreatable viral brain infection called progressive multifocal leukoencephalopathy (PML) has been associated with Tysabri use.Previous exposure to the JC virus is a very important risk factor for an increased risk of developing PML. Greater than 50% of people have been exposed to the JC virus. Testing is available free of charge through Quest Diagnostics with an order from your healthcare provider. Testing for the JC virus every 6 months is recommended unless already known to be positive. Approximately 1/4 of the MS patients who developed PML patients have died. The risk is greater when treated for more than 2 years on Tysabri or previously treated with an immunosupressant medication such as azathioprine (Imuran), cyclophosphamide (Cytoxan), methotrexate, and mitoxantrone (Novantrone).

Meet Our Team

Meet Our Team. They are here to help you fight MS.