Role of Lymphocyte Counts in MS

At the 2024 Consortium of Multiple Sclerosis Centers (CMSC) Annual Meeting, NeurologyLive sat down with MS expert Donald Negroski, MD, to discuss several of the top presentations and data on treatment switches and aging in MS. Negroski provided an overview of various presentations, offering his clinical perspective and how findings may impact care going forward.

In this conversation, the MS expert provides clinical expertise on a study examining lymphocyte counts in patients who switch between dimethyl and diroximel fumarates. Negroski gave insight on the role of lymphocyte counts and how they may impact treatment decisions and management of disease progression in patients with MS.

Transcript edited below for clarity.

Donald Negroski, MD: Lymphocytic depletion or modulation is kind of the cornerstone of how a lot of these MS drugs work. When you see changes in lymphocyte counts, you want to know, is it because of the drug or is it because of drug-drug interactions, or how it's metabolized? This particular study looked at changing from dimethyl fumarate to either diroximal fumarate or the major metabolite of both of those, monomethyl fumarate. Strangely and interestingly enough, when they changed from dimethyl fumarate to diroximal fumarate, there was a decrease in the lymphocyte count by about 27%. When they changed to the active ingredient monomethyl fumarate, the lymphocyte count actually rose around 9%. We don't know why that's that's occurring, but It's kind of interesting to know the lymphocytic kind of profile with various drugs.