Evaluate Safety/Tolerability in Portuguese Participants With RRMS Transitioning From Current Therapy

Open-label, Randomized, 2-arm, Active Comparator Study to Evaluate Safety and Tolerability in Portuguese Patients With Relapsing Remitting Multiple Sclerosis (MS) Transitioning From Current Subcutaneous Interferon Therapy to Peginterferon Beta 1a (PLEGRIDY™)

The primary objective of the study is to evaluate safety and tolerability as defined by the frequency of the adverse events (AEs) of flu-like symptoms (FLS) [chills, pyrexia, myalgia, and asthenia], injection site reactions (ISRs), and injection site reaction pain (ISR-P), over 24 weeks of treatment (the active comparator period) with PLEGRIDY 125 microgram (μg) subcutaneous (SC) every 2 weeks versus current SC IFN-β therapy in participants with Relapsing Remitting Multiple Sclerosis (RRMS).

Key Inclusion Criteria:

• A confirmed diagnosis of RRMS, as defined by McDonald criteria (2017).
• An EDSS score between 0 and 5.0.
• All female participants of childbearing potential must practice effective contraception during the study and be willing and able to continue contraception for 3 months after their last dose of study treatment.
• On continual treatment for ≥6 months with a single current SC IFN-β therapy, including IFN-β-1b 0.25 mg SC every other day or IFN-β-1a 22 μg or 44 μg SC 3 times weekly

Key Exclusion Criteria:

• Known history of human immunodeficiency virus.
• Known history of or positive test result for antibodies to hepatitis C, or current hepatitis B infection (defined as positive for hepatitis B surface antigen [HBsAg] and/or positive for hepatitis B core antibody [HBcAb]) at Screening. Participants with immunity to hepatitis B from either active vaccination (defined as negative HBsAg, positive hepatitis B surface antibody [HBsAb], and negative HBcAb) or from previous natural infection (defined as negative HBsAg, positive HBsAb immunoglobulin G, and positive HBcAb) are eligible to participate in the study (definitions are based on the Centers for Disease Control and Prevention's interpretation of the hepatitis B serology panel [CDC 2007]).
• An MS relapse that has occurred within the 50 days prior to randomization and/or lack of stabilization from a previous relapse prior to randomization (Day 1).
• Any previous treatment with PLEGRIDY.

NOTE: Other protocol defined Inclusion/Exclusion may apply