New onset lymphopenia in patients with relapsing multiple sclerosis switching from long-standing dimethyl fumarate treatment to diroximel fumarate: A case series

Mult Scler. 2024 Apr 11:13524585241242027. doi: 10.1177/13524585241242027. Online ahead of print.


Lymphopenia is a known adverse effect in patients with relapsing multiple sclerosis (RMS) treated with fumaric acids. We present a case series of four patients diagnosed with RMS with prolonged lymphocyte stability on dimethyl fumarate for over 1 year who developed significant lymphopenia after transitioning to diroximel fumarate. This case series highlights the need for further research to elucidate the risk of lymphopenia in patients switching between fumaric acids.

Keywords: Lymphopenia; dimethyl fumarate; diroximel fumarate; fumaric acid; monomethyl fumarate; multiple sclerosis.