To evaluate and track changes in CD4/CD8 T cells in PwMS who switched from DMF to DRF in routine care.

Multiple Sclerosis (MS) is a chronic relapsing and progressive neurologic disease. MS progresses in part through an inflammatory immune response, which is affected by the activity of CD4 and CD8 T Cells. Evidence suggests that certain subsets of CD8 T cells mediate neuronal damage and that other subsets regulate autoimmune responses at sites of inflammation. Diroximel fumarate (DRF) and dimethyl fumarate (DMF) convert to the same active metabolite, monomethyl fumarate (MMF), but DRF has an improved tolerability profile due to its unique chemical structure.

Review of blood work in PwMS who switched from DMF to DRF in routine care.

A paired T-test (p<0.05) analyzing 26 PwMS (88% female, average age 42.17 years old +/- 8.9 years) showed no significant difference between CD4 count prior to DRF start, after 3 months on DRF, and after 6 months of treatment. There was a significant decline in CD4 counts from 6 months to 9-12 months, and from baseline to 12 months (add % decrease). There was a significant decrease in CD8 counts from baseline to 3 months (add % decrease) after switching to DRF, from 6 months to 12 months, and from baseline to 12 months post switch to DRF.

PwMS who switched from DMF to DRF showed a statistically significant decrease in CD4 T cells over 1 year, with this shift becoming evident after 9-12 months of treatment. PwMS who switched from DMF to DRF showed a statistically significant decrease in CD8 T cell count over 1 year of treatment, with the shift becoming evident after 3 months of treatment. Changes in T cell subsets in patients treated with DRF were not associated with an increase in infections.