A Study to Evaluate Safety and Efficacy of BIIB091 in Participants With Relapsing Forms of Multiple Sclerosis

About the study

The primary objectives are to investigate the safety and tolerability of BIIB091 monotherapy in participants with relapsing multiple sclerosis (RMS) (Part 1), and to evaluate the effects of BIIB091 combination therapy with Diroximel Fumarate (DRF) compared with the DRF monotherapy arm, on the key Magnetic Resonance Imaging (MRI) measure of active Central Nervous System (CNS) inflammation (Part 2). The secondary objectives are to evaluate the effects of BIIB091 monotherapy on the MRI measures of active CNS inflammation, to evaluate the effects of BIIB091 combination therapy with DRF compared with the DRF monotherapy arm on additional MRI measures of active CNS inflammation, to investigate the safety and tolerability of BIIB091 combination therapy with DRF in participants with RMS.

Who can take part

You may be eligible to participate in the study if you meet the following criteria:

INCLUSION CRITERIA

Key Inclusion Criteria:

Diagnosis of RMS [relapsing-remitting multiple sclerosis (RRMS) or active secondary progressive multiple sclerosis (SPMS)] in accordance with the 2017 Revised McDonald criteria.
Time since MS symptom onset is <20 years.
Must have expanded disability status scale (EDSS) score of 0 through 5.0 at screening.

Must have at least 1 of the following occurring prior to Baseline (Day 1):

≥2 clinical relapses in the last 24 months (but not within 30 days prior to Baseline [Day 1]) with at least 1 relapse during the last 12 months prior to randomization.
≥1 clinical relapse within the past 24 months (but not within 30 days prior to Baseline [Day 1]) and ≥1 new brain MRI lesion (Gd positive and/or new or enlarging T2 hyperintense lesion) within the past 12 months prior to randomization. The screening MRI could be used to satisfy this criterion (if needed for inclusion, local read is required). For new or enlarging T2 hyperintense lesions, the reference scan cannot be >12 months prior to randomization.
≥1 GdE lesion on brain MRI within 6 months prior to randomization.

EXCLUSION CRITERIA

Key Exclusion Criteria:

Diagnosis of primary progressive multiple sclerosis (PPMS) in accordance with the 2017 Revised McDonald criteria.
An MS relapse that has occurred within 30 days prior to Baseline (Day 1) or the participant has not stabilized from a previous relapse at the time of screening.

History of severe allergic, anaphylactic reactions or hypersensitivity reaction to BIIB091 or DRF, the excipients contained in the formulation, and if appropriate, any diagnostic agents to be administered during the study, including the following:

Known hypersensitivity to any components of the study treatment
Known hypersensitivity to previous fumarate or bruton's tyrosine kinase (BTK) inhibitor treatments
History of hypersensitivity to parenteral administration of Gd-based contrast agents
Evidence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection within the past 4 weeks prior to Baseline.
History or positive test result at screening for human immunodeficiency virus (HIV).
Current or history of hepatitis C infection regardless of viral load.
Current or possible hepatitis B.
Current enrollment or plan to enroll in any other drug, biological, device, clinical study, or treatment with an investigational drug or approved therapy for investigational use within 90 days prior to randomization or 5 half-lives of the drug or therapy, whichever is longer.

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