Why carry out this study?

In the 96-week phase 3 EVOLVE-MS-1 study, mean absolute lymphocyte count (ALC) decreased from baseline in patients on diroximel fumarate (DRF) by approximately 28% in year 1, then stabilized, similar to the ALC decline observed in patients treated with dimethyl fumarate (DMF).

Prior studies reported that clinical efficacy of DMF was not substantially different in patients with and without lymphopenia.

The correlation of change in ALCs to DRF treatment response has not been previously determined; therefore, the aim of this analysis was to determine if lymphopenia or the magnitude of ALC decline from baseline in patients with multiple sclerosis (MS) treated with DRF correlates with DRF efficacy-related related outcomes.

What was learned from this study?

In DRF-treated patients in EVOLVE-MS-1, clinical and radiological measurements indicated reduced disease activity regardless of lymphopenia or magnitude of ALC decline from baseline.

This supports prior evidence that, while lymphopenia may contribute to fumarate efficacy outcomes, it is not the primary mechanism of action.