Efficacy of Dimethyl Fumarate in Young Adults with Relapsing-Remitting Multiple Sclerosis: Analysis of the DEFINE, CONFIRM, and ENDORSE Studies

Introduction Dimethyl fumarate (DMF) showed favorable benefit-risk in patients with relapsing-remitting multiple sclerosis (MS) in phase 3 DEFINE and CONFIRM trials and in the ENDORSE extension study. Disease activity can differ in younger patients with MS compared with the overall population. Methods Randomized patients received DMF 240 mg twice daily or placebo (PBO; years 0–2 DEFINE/CONFIRM), then DMF (years 3–10; continuous DMF/DMF or PBO/DMF; ENDORSE); maximum follow-up (combined studies) was 13 years. This integrated post hoc analysis evaluated safety and efficacy of DMF in a subgroup of young adults aged 18–29 years. Results Of 1736 patients enrolled in ENDORSE, 125 were young adults, 86 treated continuously with DMF (DMF/DMF) and 39 received delayed DMF (PBO/DMF) in DEFINE/CONFIRM. Most ( n = 116 [93%]) young adults completed DMF treatment in DEFINE/CONFIRM. Median (range) follow-up time in ENDORSE was 6.5 (2.0–10.0) years. Young adults entering ENDORSE who had been treated with DMF in DEFINE/CONFIRM had a model-based Annualized Relapse Rate (ARR; 95% CI) of 0.24 (0.16–0.35) vs. 0.56 (0.35–0.88) in PBO patients. ARR remained low in ENDORSE: 0.07 (0.01–0.47) at years 9–10 (DMF/DMF group). At year 10 of ENDORSE, EDSS scores were low in young adults: DMF/DMF, 1.9 (1.4); PBO/DMF, 2.4 (1.6). At ~ 7 years, the proportion of young adults with no confirmed disability progresion was 81% for DMF/DMF and 72% for PBO/DMF. Patient-reported outcomes (PROs) (SF-36 and EQ-5D) generally remained stable during ENDORSE. The most common adverse events (AEs) in young adults during ENDORSE were MS relapse ( n = 53 [42%]). Most AEs were mild ( n = 20 [23.3%], n = 7 [17.9%]) to moderate ( n = 45 [52.3%], n = 23 [59.0%]) in the DMF/DMF and PBO/DMF groups, respectively. The most common serious AE (SAE) was MS relapse ( n = 19 [15%]). Conclusion The data support a favorable benefit-risk profile of DMF in young adults, as evidenced by well-characterized safety, sustained efficacy, and stable PROs. Clinical Trial Information Clinical trials.gov, DEFINE (NCT00420212), CONFIRM (NCT00451451), and ENDORSE (NCT00835770).