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MS Trial Alert: Investigators Recruiting for Phase 2 Trial of Experimental BIIB091 in Relapsing MS

March 27, 2024

SUMMARY: Investigators in the U.S. and abroad are recruiting a total of 125 people with relapsing forms of MS for a phase 2 study comparing investigational BIIB091 with Vumerity® (diroximel fumarate, Biogen). The study – also called FUSION– is sponsored by Biogen.
Rationale: The experimental treatment BIIB091 inhibits an enzyme called “Bruton’s tyrosine kinase,” reducing the activation of B cells, which are immune cells that play a role in the response that affects the brain and spinal cord in MS. BIIB091 is one of several “BTK” inhibitors being tested in clinical trials involving people with different types of MS.
Eligibility and Details: Participants should be 18 to 55 years old, and diagnosed with relapsing forms of MS, which include relapsing-remitting disease and active secondary progressive disease (with relapses and/or new MRI activity). Other criteria may apply.
Participants will be randomly assigned to daily oral treatment with either BIIB091 or Vumerity for 48 weeks. At week 16, an analysis will determine if there would be a part 2 to this study, where these treatments may be combined. That study will recruit another 150 people with relapsing MS. Either way, part 1 would proceed.
The primary outcome of the first part of the study will be to compare treatment safety. In the second part of the study, researchers will be looking for benefits using brain imaging scans.
What Else is Involved? The study involves up to 20 in-person visits to the study site. Visits will involve brain MRI scans, blood draws, clinical exams, urine tests, electrocardiograms, and responding to questionnaires.
Please note: This study requires in-person visits to the study site. Precautions are being taken to reduce the on-site risks of exposure to COVID-19.
Contact: To learn more about the enrollment criteria for this study, and to find out if you are eligible to participate, please visit the study website at, call 866-633-4636 or email
In the U.S., sites are enrolling in the following cities:
Scottsdale, Arizona
Berkeley, California
Aurora, Colorado
Vero Beach, Florida
Fort Wayne, Indiana
Kansas City, Kansas
Lutherville, Maryland
Saint Louis, Missouri
Albuquerque, New Mexico
Patchogue, New York
Winston-Salem, North Carolina
Columbus, Ohio
Cordova, Tennessee
Madison, Wisconsin
Download a brochure that discusses issues to think about when considering enrolling in an MS clinical trial (PDF). Without participants in research studies, MS research would come to a standstill. Read more here

About Multiple Sclerosis

Multiple sclerosis is an unpredictable disease of the central nervous system. Currently there is no cure. Symptoms vary from person to person and may include disabling fatigue, mobility challenges, cognitive changes, and vision issues. An estimated 1 million people live with MS in the United States. Early diagnosis and treatment are critical to minimize disability. Significant progress is being made to achieve a world free of MS.

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