Immune response to vaccines is maintained in patients treated with dimethyl fumarate

OBJECTIVES: To investigate the immune response to vaccinations in patients with relapsing forms of MS treated with delayed-release dimethyl fumarate (DMF) vs nonpegylated interferon (IFN). METHODS: In this open-label, multicenter study, patients received 3 vaccinations: (1) tetanus-diphtheria toxoid (Td) to test T-cell–dependent recall response, (2) pneumococcal vaccine polyvalent to test T-cell–independent humoral response, and (3) meningococcal (groups A, C, W-135, and Y) oligosaccharide CRM(197) conjugate to test T-cell–dependent neoantigen response. Eligible patients were aged 18–55 years, diagnosed with relapsing-remitting MS (RRMS), and either treated for ≥6 months with an approved dose of DMF or for ≥3 months with an approved dose of nonpegylated IFN. Primary end point was the proportion of patients with ≥2-fold rise in antitetanus serum IgG levels from prevaccination to 4 weeks after vaccination. RESULTS: Seventy-one patients (DMF treated, 38; IFN treated, 33) were enrolled. The mean age was 45.3 years (range 27–55); 86% were women. Responder rates (≥2-fold rise) to Td vaccination were comparable between DMF- and IFN-treated groups (68% vs 73%). Responder rates (≥2-fold rise) were also similar between DMF- and IFN-treated groups for diphtheria antitoxoid (58% vs 61%), pneumococcal serotype 3 (66% vs 79%), pneumococcal serotype 8 (95% vs 88%), and meningococcal serogroup C (53% vs 53%), all p > 0.05. In a post hoc analysis, no meaningful differences were observed between groups in the proportion of responders when stratified by age category or lymphocyte count. CONCLUSIONS: DMF-treated patients mount an immune response to recall, neoantigens, and T-cell–independent antigens, which was comparable with that of IFN-treated patients and provided adequate seroprotection. CLINICALTRIALS.GOV IDENTIFIER: NCT02097849. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that patients with RRMS treated with DMF respond to vaccinations comparably with IFN-treated patients.