NCT00493298

Who might be able to join this trial:

• You must have been diagnosed with Relapsing Remitting Multiple Sclerosis (a form of MS where symptoms come and go in episodes)
• Your doctor must have already decided that Tysabri (a specific MS medication) is the right treatment for you before you sign up for the trial
• You must be new to Tysabri, meaning you have had no more than 3 Tysabri infusions before joining
• You must have had at least one MS relapse (a flare-up of symptoms) in the past year, and meet the local approved guidelines for receiving Tysabri

Who may not be able to join:

• You have a history of a serious brain infection called Progressive Multifocal Leukoencephalopathy (PML), other serious opportunistic infections, or you are at higher risk of getting these types of infections (confirm with trial site)
• You have previously tested positive for antibodies against Tysabri (meaning your body has shown a reaction against the drug)
• You are currently taking other medications that affect or suppress your immune system alongside Tysabri
• Your immune system is already weakened at the time of joining the trial
• You currently have a known active cancer
• You are pregnant, breastfeeding, or planning to become pregnant during the trial — women who are able to become pregnant must use a reliable form of birth control unless they have had a surgical procedure that prevents pregnancy

Important: Always verify eligibility with the trial site directly before applying.