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Investigating the safety of BIIB091 and its effects on brain inflammation in multiple sclerosis patients

A 2-Part, Multicenter, Randomized, Blinded, Active-Controlled Phase 2 Study to Sequentially Evaluate the Safety and Efficacy of BIIB091 Monotherapy and BIIB091 Combination Therapy With Diroximel Fumarate in Participants With Relapsing Forms of Multiple Sclerosis

Phase 2 Interventional Biogen · NCT05798520

This study is testing a new drug called BIIB091 to see if it is safe and can help reduce brain inflammation in adults with relapsing forms of multiple sclerosis.

Quick facts

PhasePhase 2
Study typeInterventional
Enrollment275 (estimated)
Ages18 Years to 55 Years
SexAll
SponsorBiogen Industry-sponsored
Locations77 sites (Scottsdale, Arizona and 76 other locations)
Trial IDNCT05798520 on ClinicalTrials.gov

What this trial studies

This study aims to evaluate the safety and tolerability of a drug called BIIB091 in adults with relapsing forms of multiple sclerosis (MS). It consists of two parts: the first part assesses BIIB091 alone or in comparison to diroximel fumarate (DRF), while the second part examines the combination of BIIB091 and DRF versus DRF alone. Researchers will monitor adverse events and use MRI scans to measure brain inflammation before and after treatment. Additionally, electrocardiograms (ECGs) will be conducted to assess heart effects.

Who should consider this trial

Good fit: Ideal candidates include adults diagnosed with relapsing-remitting or active secondary progressive multiple sclerosis who have experienced recent relapses.

Not a fit: Patients with a diagnosis of primary progressive multiple sclerosis or those who have not experienced recent relapses may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could lead to improved treatment options for patients with relapsing forms of multiple sclerosis.

How similar studies have performed: Previous studies have shown promise in using similar approaches to treat multiple sclerosis, but the specific combination of BIIB091 and DRF is novel.

Eligibility criteria

Show full inclusion / exclusion criteria 
Key Inclusion Criteria:

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

Key Exclusion Criteria:

1. Diagnosis of primary progressive multiple sclerosis (PPMS) in accordance with the 2017 Revised McDonald criteria.
2. 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.
3. 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
4. Evidence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection within the past 4 weeks prior to Baseline.
5. History of human immunodeficiency virus (HIV) infection or a positive or indeterminate test result at screening for HIV.
6. Current or history of hepatitis C infection regardless of viral load.
7. Current or history of hepatitis B infection.
8. 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.

Where this trial is running

Scottsdale, Arizona and 76 other locations

+27 more sites — see ClinicalTrials.gov for the full list.

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
View on ClinicalTrials.gov → Find more trials like this →
Conditions Relapsing Forms of Multiple SclerosisMultiple SclerosisDiroximel fumarateBIIB091
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.