A new clinical trial, published in The New England Journal of Medicine found that an experimental drug, named tolebrutinib could help delay the progression of disability in patients with non-relapsing secondary progressive multiple sclerosis (SPMS).What Is SPMS?This is a form of multiple sclerosis where symptoms steadily worsen over time. It follows an initial period of relapsing and remitting MS. Which means, overtime, the patients with SPMS experience fewer relapses, but it steadily keeps getting worse and leads to neurological decline. As of now, there are no FDA-approved treatments for non-relapsing form of SPMS, which makes this trial's results significant.As per the National Multiple Sclerosis Society, MS is an unpredictable disease of the central nervous system that disrupts the flow of information to and from the brain. There are 4 disease courses in MS, Secondary progressive multiple sclerosis (SPMS) follows the initial course of relapsing-remitting multiple sclerosis (RRMS).How Was The Study Conducted?For this study, the researchers enrolled over 1,100 MS patients who were between the ages of 18 to 60 from 264 cities in 31 countries. The participants were randomly assigned to receive either a daily dose of tolebrutinib or a placebo.What Is Tolebrutinib?It is a tyrosine kinase inhibitor, which means, it is a class of drugs that was originally designed to treat cancers like lymphoma. It works by blocking enzymes that could promote inflammation and abnormal cell activities.The study found that after six months, 22.8% of patients taking tolebrutinib had progressed in their MS-related disability, compared to 30.8% in the placebo group. This marks a 31% reduction in disability progression. The drug also showed benefits in several other areas:Improved Disability Scores: 8.6% of those who were administered with tolebrutinib showed improvement in disability, nearly double the 4.5% in the placebo groupBetter Mobility: Patients who took the drug experienced a sustained 20% improvement in a timed 25-foot walk test after three monthsReduced Disease Activity: The MRI scans too showed fewer new or enlarging brain and spinal cord lesions for those who consumed tolebrutinibAre There Any Safety Concerns?Despite its benefits, tolebrutinib comes with potential risks—most notably liver injury. Elevated liver enzyme levels, which can signal liver damage, occurred in 4% of patients taking the drug, compared to 1.6% in the placebo group. While most cases were manageable, about 1 in 200 patients showed severe elevation in liver enzymes, requiring the drug to be discontinued.“If approved, the drug will likely require intensive monitoring of liver function during the first three months,” said Dr. Robert Fox, the lead researcher and neurologist at the Cleveland Clinic. He emphasized the importance of early detection of liver-related issues to ensure safe treatment.Tolebrutinib may represent a breakthrough for patients with non-relapsing SPMS, offering the first targeted treatment for slowing disability in the later stages of the disease. “It offers the potential for a new class of medications for MS,” said Dr. Fox, “which remains the leading cause of non-traumatic disability in young adults.”Pending FDA approval, tolebrutinib could offer hope to thousands living with progressive MS, giving them not only more time but a better quality of life.