Study of Tysabri in Early Relapsing Remitting Multiple Sclerosis in Anti-JCV Antibody Negative Patients (COSTAN)

Patients who choose to participate in the study will receive a thorough description of the study protocol and an informed consent document describing the study and the risks and benefits of participating. Recruitment will continue until approximately 150 patients have been enrolled in the study at approximately 15 sites across Canada. Patients who withdraw and complete the exit interview will not be eligible to re-enroll in the study. The subject will be considered to be enrolled in the study once this identification number has been generated. Patients who convert to anti-JCV antibody positive status during the course of the study will be allowed to continue on Tysabri and in the study at the discretion of the participating neurologi

Inclusion Criteria:

• Ability to understand the purpose and risks of the study and provide signed and dated informed consent.
• Age 18 to 65 years old, inclusive, at time of informed consent.
• Documented diagnosis of Relapsing Multiple Sclerosis (McDonald 2010 Criteria [Polman et al., 2011]).
• Must have an EDSS score from 0 to 3.5, inclusive.
• Anti-JCV antibody negative test within 3 months of Screening Visit or negative test for anti-JCV antibody at Baseline Visit.
• Must satisfy the approved therapeutic indications for Tysabri and the existing reimbursement criteria as either 1st line (highly active) or 2nd line therapy in respective provinces.
• Must either be treatment naïve with highly active disease (≥ 2 relapses in the year prior to study entry and ≥ 1 Gd+ lesion on T1-weighted MRI at study entry) or have been treated with a single DMT (including Avonex, Betaseron, Rebif, Copaxone, or Extavia) for ≥12 months and ≤18 months total prior to date of informed consent.
• Decision to treat with Tysabri must precede enrollment.

Exclusion Criteria:

• Any prior treatment with Tysabri.
• Anti-JCV antibody positive at any timepoint.
• Contraindications to treatment with Tysabri as described in the Product Monograph.
• History of PML or other opportunistic infections, or an increased risk for such infections.
• History of diagnosis of Primary Progressive Multiple Sclerosis [PPMS] and/or Secondary Progressive Multiple Sclerosis [SPMS].
• Receiving immunomodulatory or immunosuppressive therapy.
• Prior history of immunosuppressive use (mitoxantrone, azathioprine, methotrexate, cyclophosphamide, mycophenolate, cladribine, rituximab).
• Immunocompromised at the time of enrollment.
• Known active malignancies (subjects with cutaneous basal cell carcinoma that has been completely excised prior to study entry remain eligible).
• Women breastfeeding, pregnant, or planning to become pregnant; women who are not post-menopausal or surgically sterile who are unwilling to practice contraception.
• Inability to comply with study requirements.