A Study to Investigate the Radiological Onset of Action After Treatment Initiation With Subcutaneous (SC) Natalizumab in Participants With Relapsing-Remitting Multiple Sclerosis (RRMS)

A Prospective, Multicenter, Interventional, Open-Label, Single-arm Phase IV Study Over 24 Weeks to Investigate the Radiological Onset of Action After Treatment Initiation With Subcutaneous Natalizumab in Patients With Relapsing-Remitting Multiple Sclerosis (TYS-ON)

The primary objective of this study is to evaluate the radiological efficacy of SC natalizumab over time through Week 24 in natalizumab-naïve participants, as measured by brain magnetic resonance imaging (MRI). The secondary objectives of this study are to evaluate additional lesion-related radiological efficacy measures over time, relapse-based clinical efficacy measures, disability improvement and worsening (EDSS), pharmacokinetic and pharmacodynamic parameters, the immunogenicity of repeated doses, and safety in treatment-naïve participants of SC natalizumab.

Key Inclusion Criteria:

• Diagnosis of RRMS according to the McDonald criteria
• Treatment-naïve in respect to natalizumab as disease modifying monotherapy for RRMS
• No or not more than one prior MS disease-modifying therapy
• Highly active RRMS, as defined by at least one relapse in the previous year and at least one T1 gadolinium-enhancing lesion or ≥3 new or enlarging T2 lesions
• EDSS score ≤ 5.5 at Screening
• Estimated glomerular filtration rate (eGFR) >30 millilitre per min (mL/min), as estimated using the Cockcroft-Gault formula.

Key Exclusion Criteria:

• Primary- and secondary-progressive MS
• Participants for whom MRI is contraindicated
• History of any clinically significant cardiac, endocrinologic, hematologic, hepatic, immunologic, metabolic (including diabetes), urologic, pulmonary, neurologic (except for RRMS), dermatologic, psychiatric, renal, or other major disease that would preclude participation in a clinical study
• History of severe allergic or anaphylactic reactions or known hypersensitivity to any antibody drug therapy.

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