In a new study, an experimental drug has been shown to slow disability progression in people living with nonrelapsing secondary progressive multiple sclerosis (SPMS). Currently, there are no approved disease-modifying therapies for this form of MS.

In a large phase 3 clinical trial, the medication tolebrutinib reduced the risk of confirmed disability progression in nonrelapsing SPMS by 31 percent compared to placebo. Tolebrutinib is an oral medication believed to work by targeting inflammation inside the brain. The drug crosses the blood-brain barrier and is designed to reach immune cells in the central nervous system (made up of the brain and spinal cord). This brain-targeting approach may help protect against nerve damage that contributes to long-term disability.

The medication was generally well-tolerated, though participants showed elevated liver enzymes in blood test results. One participant required a liver transplant and later died. Researchers plan to increase monitoring in future studies to reduce this risk.

A Promising Potential Treatment for Nonrelapsing SPMS

If approved, tolebrutinib could become the first treatment specifically designed to slow progression in people with nonrelapsing SPMS — a group that often has few treatment options. People with nonrelapsing SPMS experience worsening symptoms such as fatigue, mobility issues, or cognitive changes without relapses.

The U.S. Food and Drug Administration (FDA) is currently reviewing tolebrutinib for nonrelapsing SPMS under priority review, with a decision expected by late September 2025. Until then, it remains an investigational therapy. If tolebrutinib is approved, it will be the first drug in its class — called Bruton’s tyrosine kinase inhibitors — approved to treat progressive MS.

If you live with nonrelapsing SPMS and feel your symptoms have been getting worse without clear relapses, this study may offer new hope. If you’re interested in participating in a clinical study, talk with your neurologist about whether you might be qualified for any trials recruiting near you.

Learn about 10 signs and symptoms of SPMS.

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