Predictors of lymphocyte count recovery after dimethyl fumarate-induced lymphopenia in people with multiple sclerosis.

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.

Safety and Efficacy of Dimethyl Fumarate in Multiple Sclerosis: An Italian, Multicenter, Real-World Study.

BACKGROUND: Two phase III trials have demonstrated the clinical and radiological efficacy of delayed-release dimethyl fumarate (DMF) in relapsing-remitting multiple sclerosis (RRMS). However, data on its safety and effectiveness in real-world practice are still limited. OBJECTIVES: The aim of our study was to explore the safety and tolerability profile of DMF in RRMS. We also tried to identify individual variables associated with better clinical and radiological outcomes. METHODS: We collected the clinical and magnetic resonance imaging (MRI) data of patients with RRMS who started DMF between 2012 and 2017 in seven MS clinics in central Italy. We first evaluated DMF discontinuation rates and the incidence of adverse events and side effects. We then assessed the annualized relapse rate (ARR), the number of patients with clinical relapses or disability worsening and the presence of radiological activity. Third, we investigated which baseline variables were associated with clinical and radiological outcomes. RESULTS: We collected data for 1089 patients with a mean on-treatment follow-up of 17 ± 8 months; 331 (30.4%) of these patients were treatment naïve. In total, 210 (19.5%) patients discontinued DMF mainly because of poor tolerability (n = 103) and disease activity (n = 63), and 166 (16.5%) patients presented with lymphopenia. The ARR reduced from 0.55 to 0.13. Mean change in Expanded Disability Status Scale (EDSS) score was 0.08 ± 0.44 per year. The occurrence of clinical and/or radiological activity during follow-up was associated with younger age [hazard ratio (HR) 0.97; p < 0.001], higher EDSS score (HR 1.18; p < 0.001), greater number of Gd-enhancing lesions at baseline scan (HR 1.14; p = 0.003) and prior exposure to MS treatments (HR 1.43; p = 0.02). CONCLUSION: This post-marketing data confirms the short-term safety, tolerability and effectiveness of DMF, supporting its use as an early treatment in MS.