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

December 14, 2020

SUMMARY: Investigators in the U.S. and abroad are recruiting a total of 2280 people with progressive forms of MS for two separate studies comparing investigational oral tolebrutinib with placebo. The studies – also called HERCULES and PERSEUS – are 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 non-relapsing secondary progressive MS (HERCULES trial) or primary progressive MS (PERSEUS trial).
In both studies, 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 these studies, 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
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, often disabling disease of the central nervous system. Symptoms range from numbness and tingling to blindness and paralysis, and there is currently no cure for MS. The progress, severity and specific symptoms of MS in any one person cannot yet be predicted, but advances in research and treatment are leading to better understanding and moving us closer to a world free of MS. An estimated 1 million people live with MS in the United States. Most people with MS are diagnosed between the ages of 20 and 50, and it affects women three times more than men.


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