Due to on-going enrollment challenges

The primary objective of the study is to evaluate the impact of early treatment with Tysabri in Relapsing Remitting Multiple Sclerosis (RRMS) participants on their quality of life (QoL) as measured by Multiple Sclerosis Impact Scale-29 (MSIS-29) over 2 years. The secondary objectives of the study are: to evaluate the impact of early treatment with Tysabri in RRMS participants over 2 years on the following: annualized relapse rate (ARR), Expanded Disability Status Scale (EDSS), work productivity, quality of life (QoL) by EuroQol 5-Dimension questionnaire (EQ-5D), QoL by Subject Global Assessment of Wellbeing visual analog scale (VAS) and to evaluate clinical disease-free status (relapses, EDSS) over 2 years.

Key Inclusion Criteria:

• Ability to understand the purpose and risks of the study and provide signed and dated informed consent.
• Documented diagnosis of Relapsing Multiple Sclerosis (McDonald 2010 Criteria).
• Must have an Expanded Disability Status Scale (EDSS) score from 0 to 4.0, inclusive.
• Must satisfy the approved therapeutic indications for Tysabri as per Product Monograph.
• Must either be treatment naïve or have been treated with disease modifying therapy DMT(s) (such as, but not limited to, Avonex, Betaseron, Rebif, Copaxone, Extavia, Tecfidera and/or Gilenya) for ≤5 years total prior to date of informed consent.
• Decision to treat with Tysabri must precede enrollment.

Key Exclusion Criteria:

• Any prior treatment with Tysabri.
• Contraindications to treatment with Tysabri as described in the Product Monograph.
• History of progressive multifocal leukoencephalopathy (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.

NOTE: Other protocol defined Inclusion/Exclusion criteria may apply.

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.