Study finds certain MS therapies may not slow disability progression

With MS, the body's immune system attacks myelin, the fatty, white substance that insulates and protects the nerves. People with primary progressive MS experience a steady decline in symptoms. About 10 to 15% of people with the disease have this type of MS.

The study looked at rituximab and ocrelizumab, anti-CD20 infusion therapies that target a protein called CD20 found on some white blood cells called B-cells. Removing these cells from the bloodstream is believed to reduce inflammation and damage that can occur to the myelin. Ocrelizumab is approved by the U.S. Food and Drug Administration (FDA) for primary progressive MS and for people with relapses, but rituximab is not. Rituximab is FDA approved for other diseases like rheumatoid arthritis and prescribed off label for MS.

"MS is a disabling disease, so treatments that slow the progression to worse disability are sorely needed," said study author Laure Michel, MD, PhD, of Rennes University in France. "Anti-CD20 therapies are widely prescribed, in part because there are few alternate treatments. However, our study suggests they may not slow disability from worsening for people with primary progressive MS."

The study involved 1,184 people with primary progressive MS who had an average age of 56. They did not take MS medications in the two years prior to the study. For the study, 295 people were treated with rituximab, 131 were treated with ocrelizumab and 728 were untreated. They were followed for an average of four years.

Participants' level of disability was measured on a scale with scores ranging from zero, meaning no symptoms, to 10 points, meaning death due to MS. At the start of the study, all participants had a score of 6.5 or less.

Researchers then measured how long it took for people to advance to their first confirmed disability progression. For those whose score was less than 5.5 at the start of the study, advancing one point on the scale was considered progressing in disability. If their score was 5.5 or more, advancing 0.5 points on the scale was disability progression.

After adjusting for possible differences between the treated and untreated groups, researchers found there was no difference in the time it took to progress to the next level of disability between those taking a medication and those taking no medication.

"Medications for MS can be expensive and come with risks of side effects," said Michel. "Our results indicate that there should be a constant evaluation of MS therapies to determine if the benefits outweigh the risks for people with primary progressive MS."

A limitation of the study is that it was a look back in time and did not follow people in real time. Also, among those taking medications, most were taking rituximab with fewer people taking ocrelizumab. More research is needed in larger groups of people to confirm the findings.

The study was supported by the France National Research Agency, the French MS registry and the Eugène Devic EDMUS Foundation.