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MS Trial Alert: Investigators Recruiting for Phase 3 Trial of Experimental Tolebrutinib in Primary Progressive MS

December 14, 2020

SUMMARY: Investigators in the U.S. and abroad are recruiting 1440 people with primary progressive MS for a study comparing investigational oral tolebrutinib with placebo. This study – also called PERSEUS – is sponsored by Sanofi .
Rationale: Tolebrutinib 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. Tolebrutinib also penetrates the brain and spinal cord and inhibits immune cells in the brain called microglia, which have been linked to MS progression. Tolebrutinib is one of several “BTK” inhibitors being tested in the MS pipeline.
Eligibility and Details: Participants should be 18 to 60 years old, and diagnosed with primary progressive MS.
Participants will be randomly assigned to once daily treatment with either tolebrutinib or a placebo for a treatment duration of 24-48 months. The primary outcome of both studies will compare how treatment affects the time it takes for disability to progress using the EDSS scale. Secondary outcomes include safety, walking speed, cognitive function, disease activity on MRI scans, quality of life, and laboratory biomarkers of immune and nervous system activity. The study involves up to 16 visits to the study site, and will involve MRI scans, blood draws, clinical exams, and 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 call 1-800-633-1610 extension option 6, or email

Online - To see if you might qualify for this clinical trial and to be referred to the local trial center in your area, visit:
In the U.S., sites are enrolling in the following cities:
Boca Raton, Florida
Columbus, Ohio
Cordova, Tennessee
Dayton, Ohio
Fort Collins, Colorado
Franklin, Tennessee
Greer, South Carolina
Honolulu, Hawaii
Long Beach, California
Maitland, Florida
Naples, Florida
Northbrook, Illinois
Durham, NC
Raleigh, North Carolina
San Antonio, Texas
Savannah, Georgia
Spokane, Washington
Springfield, Illinois
Tampa, Florida
Torrance, California
Westerville, Ohio
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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