Background Dimethyl fumarate (DMF) is an oral drug approved for Relapsing Multiple Sclerosis (RMS) patients. Grade III
lymphopenia is reported in 5–10% DMF-treated patients. Data on lymphocyte count (ALC) recovery after DMF withdrawal
following prolonged lymphopenia are still scarce.
Objectives To characterize ALC recovery and to identify predictors of slower recovery after DMF interruption.
Methods Multicenter data from RMS patients who started DMF and developed lymphopenia during treatment were collected.
In patients with grade II–III lymphopenia, ALCs were evaluated from DMF withdrawal until reaching lymphocyte
counts > 800/mm3.
Results Among 1034 patients who started DMF, we found 198 (19.1%) patients with lymphopenia and 65 patients (6.3%)
who discontinued DMF due to persistent grade II–III lymphopenia. Complete data were available for 51 patients. All patients
recovered to ALC > 800 cells/mm3 with a median time of 3.4 months. Lower ALCs at DMF suspension (HR 0.98; p = 0.005),
longer disease duration (HR 1.29; p = 0.014) and prior exposure to MS treatments (HR 0.03; p = 0.025) were found predictive
of delayed ALC recovery.
Conclusion ALC recovery after DMF withdrawal is usually rapid, nevertheless it may require longer time in patients with
lower ALC count at DMF interruption, longer disease duration and previous exposure to MS treatments, potentially leading
to delayed initiation of a new therapy.
- Dimethyl fumarate
- Multiple sclerosis
- Real-world study